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 η\eta Photoproduction on Protons Found Using Dispersion Relations and an Isobar Model

The contributions of the resonances $D_{13}(1520)$, $S_{11}(1535)$, $S_{11}(1650)$, $D_{15}(1675)$, $F_{15}(1680)$, $D_{13}(1700)$, $P_{11}(1710)$, $P_{13}(1720)$ to $\gamma p\to \eta p$ 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 $D_{13}(1520)$, $S_{11}(1535)$, $F_{15}(1680)$ to corresponding multipole amplitudes are stable. With this the results for $D_{13}(1520)$ and $F_{15}(1680)$, combined with their PDG photoexcitation helicity amplitudes, allowed us to find the branching ratios $Br (D_{13}(1520)\to \eta N)=0.05\pm 0.02$, $Br (F_{15}(1680)\to \eta N)=0.16\pm0.04$ which have significantly better accuracy than the PDG data. The total Breit-Wigner width of the $S_{11}(1535)$ is model-dependent, we have obtained $\Gamma (S_{11}(1520))=142 MeV$ and $195 MeV$ using dispersion relations and the isobar model, respectively. The results for the $S_{11}(1650)$, $D_{15}(1675)$, $P_{11}(1710)$, $P_{13}(1720)$ are model dependent, only the signs and orders of magnitude of their contributions to multipole amplitudes are determined. The results for the $D_{13}(1700)$ 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