1,730 research outputs found
A Parametric Study of Vane and Air-jet Vortex Generators
No full textAn experimental parametric sturdy of vane and air-jet vortex generators in a turbulent boundary
layer has been carried out. Experiments were carried out in two facilities, one with a free-stream
velocity of 20 m/s and a boundary layer thickness (6) of 41.5 mm, and one in a high speed facility
at free-stream Mach numbers of between 0.45 and 0.75 and a boundary layer thickness of 20 mm.
Cross-stream data were measured at a number of downstream locations using a miniature five-hole
pressure probe, such that local cross-stream velocity vectors could be derived. Streamwise
vorticity was calculated using the velocity vector data.
In the low speed study, vortex generator parameters were as follows:
" Vane vortex generators: thin rectangular vanes with a vane aspect ratio of unity (2h/c = 1),
free-stream velocity 20 m/s, incidence (cc = 10', 15', 18', 20'), height-to-boundary- layer-
thickness-ratio (h/8 0.554,0.916,1.27,1.639), and strearnwise distance from the vortex
generator (x/6 = 3.855,12.048,19.277,26.506).
" Air-jet vortex generators: circular jet nozzles, free-stream velocity = 20 m/s, jet nozzle pitch
and skew angles (cc, P= 30', 45', 60'), hole diameter-to-boundary-layer-thickness-ratio (D/5 =
0.098,0.193,0.289), jet-to-free-stream-velocity ratio (VR = 0.7,1.0,1.3,1.6,2.0), and
strearnwise distance from the vortex generator (x/8 = 3.855,12.048,19.277,26.506).
In the high-speed study, the vortex generator parameters were as follows:
Vane vortex generators: thin rectangular vanes with an aspect ratio of unity, incidence ((X
1505 20'), he i ght-to- boundary- I ayer-th i ckne s s-rati o (h/8 = 0.75), strearnwise distance from the
vortex generator (x/6 = 8.755 16.25,23.75), and free-stream Mach numbers of 0.45,0.6 and
0.75.
Air-jet vortex generators: jet pitch ((x = 30', 45'), jet skew angle (P = 30', 45', 60'), hole
diameter-to-boundary-layer-thickness-ratio (D/8 = 0.15,0.3), j et-to- free- strearn-ve loc ity ratio
(VR = 1.6), and strearnwise distance from the vortex generator (x/6 = 8.75,16.25,23.75,
31.25), and free-stream Mach numbers of 0.50,0.6 and 0.75.
Streamwise vorticity data from the experiment was used to generate prediction techniques that
would allow the vorticity profiles, downstream of vane or air-jet vortex generators, to be predicted.
Both techniques are based on the approximation of the experimental cross-stream vorticity data to
Gaussian distributions of vorticity through the vortex centre. The techniques, which are
empirically derived, are simple equations that give the peak vorticity and vortex radius based on
the vortex generator parameters. Use of these descriptors allows the assembly of the Gaussian
vorticity equation.
Both techniques are compared with the experimental data set and were seen to produce peak
vorticity results to within 12% and 20% (for the vanes and air-jets respectively), 15% for the
radius of the vortex, and 15% and 20% in vortex circulation (for the vanes and air-jets
respectively). The two simple prediction techniques allow good prediction of the vortex structure
at extremely low computational effort
Evaluating Citebase, an open access Web-based citation-ranked search and impact discovery service
No full textCitebase is a new citation-ranked search and impact discovery service that measures citations of scholarly research papers which are openly accessible on the Web, i.e. papers that are assessable continuously online. Other services, such as ResearchIndex, have emerged in recent years to offer citation indexing of Web research papers. In the first detailed user evaluation of an open access Web citation indexing service, Citebase has been evaluated by nearly 200 users from different backgrounds. The paper details the procedures used in the evaluation, and analyses the results of this study, which took place between June and October 2002. It was found that within the scope of its primary components, the search interface and services available from its rich bibliographic records, Citebase can be used simply and reliably for the purpose intended, and that it compares favourably with other bibliographic services. It is shown tasks can be accomplished efficiently with Citebase regardless of the background of the user. More data need to be collected and the process refined before it is as reliable for measuring citation impact of indexed papers. Better explanations and guidance are required for first-time users. Coverage is seen as a limiting factor, even though Citebase indexes over 200,000 papers from arXiv. Non-physicists were frustrated at the lack of papers from other sciences. The principle of citation searching of open access archives has thus been demonstrated and need not be restricted to current users. Since the evaluation, Citebase has become a featured service of the ArXiv physics eprint archives
Author Talk
No full textUniversity president, Jim Schmotter, introduces Tim O'Brien at the author talk in Ives Auditorium, October 26, 2010.</p
Who Belongs? Immigrants, Refugees, Migrants, and Actions Towards Justice: A Conversation With Tim Wise
No full textTim Wise is an antiracist activist, essayist and author of seven books on racism, inequality and white privilege. He is among the most prominent anti-racist writers and educators in the United States. Over the past 25 years he has engaged audiences in all 50 states, at over 1000 college and high school campuses, at hundreds of professional and academic conferences, and to community groups across the country. While visiting Iowa State University Tim Wise interviewed with us to discuss Who Belongs? by providing a brief historical perspective of immigration, the current political climate, and the role of activism.</p
PERMANOVA results based on Bray–Curtis dissimilarities using abundance data for microbiome.
No full textPERMANOVA results based on Bray–Curtis dissimilarities using abundance data for microbiome.</p
Accepting Optimally in Automated Negotiation with Incomplete Information (abstract)
No full textIntelligent SystemsElectrical Engineering, Mathematics and Computer Scienc
Whose Voice? Tim Crouch’s The Author and Active Listening on the Contemporary Stage
No full textThe essay discusses Tim Crouch’s recent play The Author (2009) in the context of active listening, audience participation, response and responsibility in contemporary theatre. It provides a critical engagement with the spectatorial experience of the piece so as to problematize the multiple uses of the physical medium of voice and speech in a contemporary play that delivers a fresh angle to narrativity and metatheatricality. At the same time, the essay probes the varied range of possibilities but also realistic extent of audience involvement in the play, tracing its deep textual contingencies to produce an overall understanding of the equally rewarding and precarious interrelationship between performance piece and audience.</p
UTSim2 validation
No full textThe Center for NDE (CNDE) at Iowa State University has a long history of developing physics models for NDE and packaging these models into simulation tools which make the modeling capabilities accessible to CNDEs industrial sponsors. Recent work at CNDE has led to the development of a new ultrasonic simulation package, UTSim2, which aims to continue this tradition of supporting industrial application of CNDE models. In order to meet this goal, UTSim2 has been designed as an extensible software package which can support previously-developed physics models as well as future models yet to be developed. Initial work has focused on the implementation of a Gauss-Hermite beam model, a paraxial approximation, which is implemented as part of the Thompson-Gray measurement model. This paper will present recent validation results and include comparisons against both previously-validated model output and newly-performed experiments.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This proceeding appeared in Grandin, Robert, and Tim Gray. "UTSim2 validation." AIP Conference Proceedings, 1806, no. 1 (2017): 150007, and may be found at DOI: 10.1063/1.4974731. Posted with permission.</p
Nostalgia: content, triggers, functions
No full textSeven methodologically diverse studies addressed 3 fundamental questions about nostalgia. Studies 1 and 2 examined the content of nostalgic experiences. Descriptions of nostalgic experiences typically featured the self as a protagonist in interactions with close others (e.g., friends) or in momentous events (e.g., weddings). Also, the descriptions contained more expressions of positive than negative affect and often depicted the redemption of negative life scenes by subsequent triumphs. Studies 3 and 4 examined triggers of nostalgia and revealed that nostalgia occurs in response to negative mood and the discrete affective state of loneliness. Studies 5, 6, and 7 investigated the functional utility of nostalgia and established that nostalgia bolsters social bonds, increases positive self-regard, and generates positive affect. These findings demarcate key landmarks in the hitherto uncharted research domain of nostalgi
broadinstitute/cell-health: Preprint Analysis Code
No full textComplete analysis code for the preprint submission for "Predicting cell health phenotypes using image-based morphology profiling"
Gregory P. Way+, Maria Kost-Alimova+, Tsukasa Shibue, William F. Harrington, Stanley Gill, Tim Becker, William C. Hahn, Anne E. Carpenter^, Francisca Vazquez^, Shantanu Singh^
+Co-First Authors ^Co-Senior Author
- …
