2,654 research outputs found
Herstellung und Charakterisierung von schmalbandigen EUV-Multischichtenspiegeln für Anwendungen mit fs-HHG-Strahlung
No full textLim Y. Herstellung und Charakterisierung von schmalbandigen EUV-Multischichtenspiegeln für Anwendungen mit fs-HHG-Strahlung. Bielefeld (Germany): Bielefeld University; 2001.Schmalbandige EUV-Multischichtspiegel wurden mittels Elektronenstrahlverdampfung im UHV unter Variation des Verhältnisses [Gamma] zwischen Absorber- und Doppelschichtdicke hergestellt. Diese Multischichten wurden entwickelt für die spektrale Selektion einzelner Hoher Harmonischer einer fs-EUV-Quelle mit Photonenenergien unterhalb von 73 eV. Hierfür wird eine Bandbreite von [Delta]E FWHM <= 3 eV benötigt.
Bei der Herstellung der Multischichten wird die Dicke jeder einzelnen Schicht mit dem in situ Röntgenreflektometer kontrolliert. Multischichten mit kleinen [Gamma]-Werten wurden hergestellt, indem die Verdampfer in jedem Maximum (Mo) und in jedem zweiten Minimum (Si) der in situ Reflektivitätskurve umgeschaltet wurden. Die Methoden Ionenpolieren und Substratheizen wurden für die Minimierung der Grenzflächenrauhigkeit angewendet und miteinander verglichen.
Die Eigenschaften der Multischichtspiegel sind durch Reflektometrie mit harter und weicher Röntgenstrahlung sowie TEM-Querschnittsaufnahmen charakterisiert worden. Messungen mit Hohen Harmonischen aus fs-Laser Frequenzmischung zeigen, dass zwei dieser Multischichten in Serie eine ausreichend schmale Bandbreite besitzen, um z.B. die 45. Harmonische bei 69,8 eV zu selektieren
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Parallel Finger Search Structures
No full textIn this paper we present two versions of a parallel finger structure FS on p processors that supports searches, insertions and deletions, and has a finger at each end. This is to our knowledge the first implementation of a parallel search structure that is work-optimal with respect to the finger bound and yet has very good parallelism (within a factor of O(log p)^2) of optimal). We utilize an extended implicit batching framework that transparently facilitates the use of FS by any parallel program P that is modelled by a dynamically generated DAG D where each node is either a unit-time instruction or a call to FS.
The work done by FS is bounded by the finger bound F_L (for some linearization L of D), i.e. each operation on an item with distance r from a finger takes O(log r+1) amortized work. Running P using the simpler version takes O((T_1+F_L)/p + T_infty + d * ((log p)^2 + log n)) time on a greedy scheduler, where T_1, T_infty are the size and span of D respectively, and n is the maximum number of items in FS, and d is the maximum number of calls to FS along any path in D. Using the faster version, this is reduced to O((T_1+F_L)/p + T_infty + d *(log p)^2 + s_L) time, where s_L is the weighted span of D where each call to FS is weighted by its cost according to F_L. FS can be extended to a fixed number of movable fingers.
The data structures in our paper fit into the dynamic multithreading paradigm, and their performance bounds are directly composable with other data structures given in the same paradigm. Also, the results can be translated to practical implementations using work-stealing schedulers
Spectral shaping of an OPCPA preamplifier for a sub-20-fs multi-PW laser
No full textWe developed an OPCPA preamplifier with an actively shaped output spectrum to obtain a sub-20-fs-duration pulse for a 4-PW laser. The active spectral shaping was facilitated by controlling the temporal profile of a pump pulse in the OPCPA preamplifier. By optimizing the output spectrum of the OPCPA to compensate for the gain-depletion effect in the 4-PW laser, a final laser pulse with a broad spectrum of 101-nm in width (FWHM), resulting in a short pulse duration of 17 fs, was achieved. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreeme
Improved terminal sliding mode control based on MPC for LIM applied to linear metro
No full textAbstract To improve the dynamic response of the linear induction machine (LIM) over its complete speed range, this paper introduces a finite state-model predictive voltage control (FS-MPVC) based on terminal sliding mode control (TSMC). First, the TSMC for the speed loop is designed to attain high tracking capability and faster transient response. Second, in terms of the intricate balancing coefficient tuning difficulty and several computation steps of the conventional finite state-model predictive thrust control method, the control objectives are transformed to the primary voltage based on the FS-MPVC method. Furthermore, the TSMC-MPVC is fully studied in detail, covering its design and implementation steps. Ultimately, a 3 kW LIM has undergone comprehensive simulation evaluations by the presented TSMC-MPVC through comparing with the conventional methods at various speeds and loads to verify the effectiveness and viability of the proposed method
FSD-FS
No full textFSD-FS is a publicly-available database of human labelled sound events for few-shot learning. It spans across 143 classes obtained from the AudioSet Ontology and contains 43805 raw audio files collected from the FSD50K. FSD-FS is curated at the Centre for Digital Music, Queen Mary University of London.
Citation
If you use the FSD-FS dataset, please cite our paper and FSD50K.
@article{liang2022learning,
title={Learning from Taxonomy: Multi-label Few-Shot Classification for Everyday Sound Recognition},
author={Liang, Jinhua and Phan, Huy and Benetos, Emmanouil},
journal={arXiv preprint arXiv:2212.08952},
year={2022}
}
@ARTICLE{9645159, author={Fonseca, Eduardo and Favory, Xavier and Pons, Jordi and Font, Frederic and Serra, Xavier}, journal={IEEE/ACM Transactions on Audio, Speech, and Language Processing}, title={FSD50K: An Open Dataset of Human-Labeled Sound Events}, year={2022}, volume={30}, number={}, pages={829-852}, doi={10.1109/TASLP.2021.3133208}}
About FSD-FS
FSD-FS is an open database for multi-label few-shot audio classification containing 143 classes drawn from the FSD50K. It also inherits the AudioSet Ontology. FSD-FS follows the ratio 7:2:1 to split classes into base, validation, and evaluation sets, so there are 98 classes in the base set, 30 classes in the validation set, and 15 classes in the evaluation set (More details can be found in our paper).
LICENSE
FSD-FS are released in Creative Commons (CC) licenses. Same as FSD50K, each clip has its own license as defined by the clip uploader in Freesound, some of them requiring attribution to their original authors and some forbidding further commercial reuse. For more details, ones can refer to the link.
FILES
FSD-FS are organised in the structure:
root
|
└─── dev_base
|
└─── dev_val
|
└─── eval
REFERENCES AND LINKS
[1] Gemmeke, Jort F., et al. "Audio set: An ontology and human-labeled dataset for audio events." 2017 IEEE international conference on acoustics, speech and signal processing (ICASSP). IEEE, 2017. [paper] [link]
[2] Fonseca, Eduardo, et al. "Fsd50k: an open dataset of human-labeled sound events." IEEE/ACM Transactions on Audio, Speech, and Language Processing 30 (2021): 829-852. [paper] [code
Yb-doped femtosecond lasers and their frequency doubling
No full textUltralow threshold, compact and highly efficient femtosecond lasers based on Yb³⁺-doped
potassium yttrium tungstate (Yb:KYW) and Yb³⁺-doped vanadium yttrium oxide
(Yb:YVO 4 ) have been demonstrated within this PhD-research project. For a continuous
wave unmode-locked Yb:KYW laser a threshold as low as 101 mW was obtained with a
slope efficiency of 74%. By employing a single prism for dispersion control, the laser was
tunable between 1012 nm to 1069 nm. When operated in the mode-locked regime, this
laser produced transform-limited pulses having durations of 210 fs at a central wavelength
of 1044 nm. Stable mode locking was observed for an optimised incident pulse fluence on
the SESAM between 140 μJ/cm²
to 160 μJ/cm²
which was 2-3 times higher than the
designed energy pulse fluence of the SESAM (70 μJ/cm²).
The employment of several combinations of chirped mirror designs for control of
intracavity group velocity dispersion led to excellent results. The threshold for mode
locking was satisfied for a pump power of 255 mW where the slope efficiency was
measured to be 62%. This is the most efficient SESAM-assisted femtosecond laser yet
reported and the highest optical-to-optical efficiency of 37% is exceptional. Transform-limited pulses with durations as short as 90 fs were produced in a spectral region centred
on 1052 nm. The success of this research thus represents a good foundation on which to
design and build more compact configurations that will incorporate just one chirped mirror
for dispersion compensation.
A relatively high nonlinear refractive index, n₂ , of 15 x 10⁻¹⁶ cm²/W was measured
in Yb:YVO₄ and this affords particular potential for this candidate material in Kerr-lens
mode locking. In fact, for operation in the femtosecond domain, the threshold power was
190 mW with a slope efficiency of 26% and near-transform-limited pulses as short as 61fs were generated at a centre wavelength of 1050 nm. The main objectives in developing
this type of laser relate to a demonstration of high peak power operation in thin disc laser
configurations.
The deployment of a diode-pumped Yb:KYW femtosecond laser as a pump source
for frequency doubling in a periodically-poled LiTaO₃ crystal was realised. The maximum
realized output power of 150 mW corresponded to an impressive second harmonic
conversion efficiency of 43%. 225-fs duration green pulses (centred at 525 nm) were
generated under the condition of strong focusing in the nonlinear crystal
Tissue architecture of the anterior pituitary showing the epithelial cell cords with hormonal cells and folliculo-stellate (FS) cells, the capillaries (C) with fenestrated endothelial cells (EC) and connective tissue (CT)
No full text<p><b>Copyright information:</b></p><p>Taken from "Paracrinicity: The Story of 30 Years of Cellular Pituitary Crosstalk"</p><p></p><p>Journal of Neuroendocrinology 2008;20(1):1-70.</p><p>Published online Jan 2008</p><p>PMCID:PMC2229370.</p><p>© 2008 The Author. Journal Compilation © 2008 Blackwell Publishing Ltd</p> The cell cords are a cluster of endocrine cells surrounding an aggregate of FS cells that make a follicle (F). FS cells also make a meshwork between the hormonal cells, making junctions among each other (thick lines) and extending foot processes (f) ending on the basal membrane (BM) in the periphery of the cord. The cords are surrounded by BM, which may have extensions between some cells. A second BM surrounds the capillary vessels and between these two some connective tissue resides. Small and larger lacunae are present between hormonal cells. Paracrine substances may circulate from cell-to-cell but also could be released in these lacunae and reach more remote places. FS cells make gap junctions mostly among each other, but occasionally also with some hormonal cells. Hormonal cells can make interdigitations with FS cells (small arrows) to favour cell-to-cell communication. Adapted from Vila-Porcile ()
Adaptive pulse compression for transform-limited 15-fs high-energy pulse generation
No full textWe demonstrate the use of a deformable-mirror pulse shaper, combined with an evolutionary optimization algorithm, to correct high-order residual phase aberrations in a 1-mJ, 1-kHz, 15-fs laser amplifier. Frequency resolved optical gating measurements reveal that the output pulse duration of 15.2 fs is within our measurement error of the theoretical transform limit. This technique significantly reduces the pulse duration and the temporal prepulse energy of the pulse while increasing the peak intensity by 26%. It is demonstrated, for what is believed to be the first time, that the problem of pedestals in laser amplifiers can be addressed by spectral-domain correction
Through the Eyes of the User: Evaluating Neonatal Intensive Care Unit Design
No full textObjective: This article presents a pilot study that employed a user-centered methodology for evaluating and quantifying neonatal intensive care unit (NICU) designs based on the needs of the primary users. Background: The design of NICUs has begun to shift from open-bay to single-family rooms. Both designs present unique advantages and challenges that impact babies, families, and caregivers. Methods: One NICU design was analyzed using the functional scenario (FS) analysis method. For the FS, users’ needs were determined through literature review, interviews with NICU providers and parents, and a review of published design guidelines. Quantitative metrics were developed for each FS, so that characteristics of the NICU design could be analyzed to determine how successful they were in meeting the users’ needs. The results were graphically represented to visualize the success and considerations of the design. Results: A total of 23 FSs and 61 spatial metrics were developed. FSs for babies focused on infection prevention, minimizing exposure to environmental stimuli, and supporting enriching care activities. FSs for family members focused on direct access to the baby, and privacy and adequate space for daily activities. FSs for providers and caregivers focused on infection prevention, care activities, care zones, and visibility. Conclusion: Using an FS approach highlights design characteristics in the NICU that need to be addressed during the design process to more successfully meet the needs of the different users. Additionally, using this approach can inform design professionals’ decision-making by presenting them with the design characteristics that impact the needs of the user groups. </jats:sec
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