18,463 research outputs found
Laser anemometer measurements of trailing vortices in water
A series of measurements of trailing vortices behind lifting hydrofoils is described. These measurements were made in the Caltech Free-Surface Water Tunnel, using a laser-Doppler velocimeter to measure two components of velocity in the vortex wake. Two different model planforms were tested, and measurements were made at several free-stream velocities and angles of attack for each. Velocity profiles were measured at distances downstream of the model of from five to sixty chord lengths. These measurements are the first results of a continuing experimental programme.
In § 3 of this paper, the theory of trailing vortices is discussed. The effects of ‘vortex wandering’ upon the measurements are computed, and the corrected results are seen to be in reasonable agreement with the theory
An analytical investigation of a simplified thrust-vector orientation technique for establishing lunar orbits
Simplified thrust vector orientation technique for establishing lunar orbit
Resonance Contributions to Photoproduction on Protons Found Using Dispersion Relations and an Isobar Model
The contributions of the resonances , ,
, , , , ,
to are found from the data on cross
sections, beam and target asymmetries using two approaches: fixed-t dispersion
relations and an isobar model. Utilization of the two approaches and comparison
of the results obtained with different parametrizations of the resonance
contributions allowed us to make conclusions about the model-dependence of
these contributions. We conclude that the results for the contributions of the
resonances , , to corresponding
multipole amplitudes are stable. With this the results for and
, combined with their PDG photoexcitation helicity amplitudes,
allowed us to find the branching ratios , which have significantly
better accuracy than the PDG data. The total Breit-Wigner width of the
is model-dependent, we have obtained and using dispersion relations and the isobar model,
respectively. The results for the , ,
, are model dependent, only the signs and orders
of magnitude of their contributions to multipole amplitudes are determined. The
results for the are strongly model-dependent.Comment: 26 pages, 6 figure
From rag picking to riches: fashion education meets textile waste
Referred to as the 'Golden Dustman' (Evans 1998) Martin Margiela's approach to sourcing and reworking vintage garments was likened to that of a Victorian ragpicker. Today, the abundance of second hand clothing donated to charity shops presents fashion designers with the opportunity to reprise Margiela's role, by considering textile waste as valuable, raw materials. Donating unwanted garments to charity is a prolific cultural practice, perceived as philanthropic and sustainable. However, donations of unwanted clothing comprise 80% fast fashion, which cannot easily be re-used, re-sold or biodegraded. Emmanuel House, a homeless charity in Nottingham have a three-tier sorting system: 1. To clothe its service users; 2. for re-sale in the charity’s shop to fund its work; 3. to be sold as 'rag' by the kilo (shipped to 3rd world countries). This conversion to cash process raises various ethical concerns. This paper reports on a social/design innovation collaboration between Emmanuel House, and Year One BA Fashion Design students, which is raising awareness of what happens to clothing donated to charities, including: the resource rich sorting process; unwanted clothing versus clothing poverty; the potential for a circular design approach at end of product lifetime; how strategic re-design can lead to innovative, suitable clothes that enhance user experience and self-esteem. Through volunteering for Emmanuel House, the students have acquired insights into homelessness and sorting charitable donations. By using their tacit knowledge of textile quality and performance, garment construction, fit and silhouette, they have identified valuable materials within existing garments. The selected items formed the basis for critically designed solutions, created using a 'deconstruction/ reconstruction' methodology, incorporating upcycling, customization, overdyeing and repair. Outcomes integrate practical details to accommodate rough sleeping and outdoor, nomadic living, including: waterproof/warm outerwear; multifunctionality/ transformability; multiple pockets for carrying/concealing items; e-textile functionality to augment light/ heat
Tagging Scientific Publications using Wikipedia and Natural Language Processing Tools. Comparison on the ArXiv Dataset
In this work, we compare two simple methods of tagging scientific
publications with labels reflecting their content. As a first source of labels
Wikipedia is employed, second label set is constructed from the noun phrases
occurring in the analyzed corpus. We examine the statistical properties and the
effectiveness of both approaches on the dataset consisting of abstracts from
0.7 million of scientific documents deposited in the ArXiv preprint collection.
We believe that obtained tags can be later on applied as useful document
features in various machine learning tasks (document similarity, clustering,
topic modelling, etc.)
Does gravity cause load-bearing bridges in colloidal and granular systems?
We study structures which can bear loads, "bridges", in particulate packings. To investigate the relationship between bridges and gravity, we experimentally determine bridge statistics in colloidal packings. We vary the effective magnitude and direction of gravity, volume fraction, and interactions, and find that the bridge size distributions depend only on the mean number of neighbors. We identify a universal distribution, in agreement with simulation results for granulars, suggesting that applied loads merely exploit preexisting bridges, which are inherent in dense packings
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