1,283 research outputs found
An experimental approach for the determination of axial and flexural wavenumbers in circular exponentially tapered bars.
No full textData and code (as Jupyter notebook) allowing for generating results presented in figures in Michał K. Kalkowski, Jen M. Muggleton, Emiliano Rustighi, An experimental approach for the determination of axial and flexural wavenumbers in circular exponentially tapered bars, Journal of Sound and Vibration, Volume 390, 3 March 2017, Pages 67-85, ISSN 0022-460X, http://dx.doi.org/10.1016/j.jsv.2016.10.018
Work was funded by EPSRC, Assessing the Underworld (EP/K021699/1) </span
Spinal fusion for lumbar instability: does it have a scientific basis?
No full textSummary: The validity of spinal fusion for lumbar instability is considered. Some difficulty lies in the interpretation of the term instability. The differing interpretations in the clinical, radiologic, and biomechanical contexts are discussed. These interpretations may only be reconciled if the confusion between hypermobility and instability is removed and some recourse is made to soft tissue integrity. Fusion is considered in the context of the functioning spine as a whole. Although the aim of the surgery is usually to produce a solid arthrodesis, some studies show that this can compromise the functioning of the rest of the spine. Furthermore, there is some evidence that pseudarthrosis itself may not be detrimental. Dynamic imaging offers the potential for improved diagnosis and assessment, but further work is needed to pave the way for better selection criteria and treatment strategies
Assessing the quality of the time delay estimate in acoustic leak localisation
No full textThe problem considered in this paper is assessing the quality of the time delay estimate between leak signals measured on water pipes. This is practically important, as a quantitative assessment of the accuracy of time delay estimation (TDE) results makes it possible to infer the reliability of acoustic leak localisation results in a given situation. Three quality assessment approaches are developed by considering the statistical properties of the cross-correlation function (CCF): information-criterion, processing gain, and statistical approaches. In the information-criterion approach, the Bayes factor (BF) is employed to decide the most likely probability distribution of observed CCF peak values. The processing gain approach determines the quality of the time delay estimate using indices that indicate detectability of the CCF peak, namely, the peak-to-side lobe ratio (PSR) and the peak-to-mean ratio (PMR). In the statistical approach, an index termed inconsistency score (ICS) is used to describe the quality of TDE results based on root-mean square of deviations of time delay estimates from their statistical mode. Experimental results show that the proposed approaches provide effective means of assessing the accuracy of the time delay estimate in acoustic leak detection applications. Also, the proposed indices can be employed as figures of merit for selecting best parameters for TDE, for example, filter cut-off frequencies
Cross-spectral phase method for time delay estimation in acoustic leak detection
No full textThis paper introduces a method for estimating time delays in acoustic/vibration leak signals within water distribution systems, using linear segmentation of the cross-spectral phase. The method applies linear regression to undistorted regions of the phase, automatically identified by a simple algorithm, to calculate the time delay. Simulation and experimental results demonstrate that the method accurately estimates time delays without the need for pre-filtering, even in the presence of multiplicative noise that distorts the cross-spectral phase—offering a significant improvement over correlation-based techniques. Furthermore, the method provides a confidence interval that quantifies the uncertainty in the estimated leak location, thereby enhancing the reliability of leak localisation
Vibration of an exponentially tapered rod embedded in an elastic solid - A piecewise uniform approach
No full textExponentially tapered rods can serve as a simplified physical model for tree roots. Based on an analytical solution for axial waves in a uniform embedded rod, we present a piecewise uniform formulation for modelling the dynamics of a tapered embedded rod. First, we revisit the uniform rod solution and discuss its characteristics. The piecewise uniform approach, in which the tapered rod is approximated as a multi-step structure composed of a number of uniform components, is presented next. The dynamics of the built-up waveguide are written in terms of propagating waves that scatter at the junctions. The assumption is made that the surrounding elastic medium has no effect on the scattering. We conduct a numerical convergence study and verify the accuracy of our model against an axisymmetric finite element (FE) simulation with perfectly absorbing boundaries. Both predictions are in very good agreement except for the low frequency range, where an assumption regarding the boundary contidions is expected to play a role. Finally, some basic observations are given in the context of the dynamics of a free tapered rod.</p
Superimposed imaging of acoustic wave reflections for the detection of underground nonmetallic pipelines
No full textDue to the non-conductive and non-magnetic properties, nonmetallic pipelines are difficult to be detected by traditional pipe location technologies. This paper presents a superimposed imaging method of acoustic wave reflections for pipe location, which operates on the propagation of elastic waves. The propagation and attenuation model of elastic waves in soil are constructed according to the geometric relationship between the acoustic source, geophone array and pipelines. The two-dimensional and three-dimensional acoustic field diagrams of underground pipeline are generated by superimposed imaging of the cross-correlation coefficients between the signals from the sound source and geophone array, with the attenuation caused by hysteretic damping and geometric dissipation considered in the imaging process. In order to suppress clutter interference on the imaging results, the strategy of ‘multi-point transmit, multi-point receive and cross-correlation coefficient superposition’ is adopted. In the simulation, comparison is made to demonstrate the influences of different excitation sources on the detection imaging results, including the single frequency signal, multi-frequency signal, Gaussian pulse signal and sweep signal. It is found that the excitation signals with rich frequency components are more conducive to improving the resolution of detection images. The effectiveness of the proposed imaging method is further verified in the experimental work, which may be beneficial for the visualization and determination of the location, depth and orientation of underground non-metallic pipelines
Jen Delos Reyes
No full textProjects in this collection: Open Engagement
From http://www.jendelosreyes.com/about: Jen Delos Reyes was born in the city of Winnipeg, Manitoba, Canada, and educated first in its local music scene of the mid-90’s infused with the energy of Riot grrrl and DIY, and then in its university. [1] How she works today is rooted in what she learned in her formative years as a show organizer, listener, creator of zines, and band member. Graduate work at the University of Regina made the space possible for her to see her work as an organizer as a key component of her continued creative work.
Jen Delos Reyes is a \u27farmer of sorts and an artist of sorts\u27[2], educator, writer, and radical community arts organizer. She is defiantly optimistic, a friend to all birds, and proponent that our institutions can become tender and vulnerable. Her practice is as much about working with institutions as it is about creating and supporting sustainable artist-led culture.
Delos Reyes worked within Portland State University from 2008-2014 to create the first flexible residency Art and Social Practice MFA program in the United States and devised the curriculum that focused on place, engagement, and dialogue. The flexible residency program allowed for artists embedded in their communities to remain on site throughout their course of study.
She worked with the Portland Art Museum from 2009-14 on a series of programs and integrated systems that allowed artists to rethink what can happen in a museum, and reinvigorate the idea of the museum as a public space.
From 2015-2022 Delos Reyes was the Associate Director of the School of Art & Art History of the University of Illinois, Chicago’s only public research university, where she taught in the departments of Art and Museum and Exhibition Studies.
She was the Director and founder of Open Engagement, an international annual conference on socially engaged art that was active between 2007-2019 and hosted ten conferences in two countries at locations including the Queens Museum in New York. After over a decade of large scale organizing she is now focused on work on the scale of her life.
She is the author of I’m Going to Live the Life I Sing About in My Song: How Artists Make and Live Lives of Meaning, Everything You Ever Wanted to Know About Public Engagement But Were Afraid to Ask, and Defiantly Optimistic: Turning Up in a World on Fire.
Delos Reyes divides her time between Chicago, IL where she is the founder of Garbage Hill Farm, and Ithaca, NY where she is an Associate Professor of Art at Cornell University.
[1] Credit to Saul Alinsky in form, and for the reminder that often the most formative educational experiences happen outside of the classroom.
[2] Grateful to Wendell Berry in general, and for this descriptor I am using.https://pdxscholar.library.pdx.edu/artandsocialpractice_creators/1030/thumbnail.jp
A Personal Journey with Gish Jen, Author
No full textBorn and raised in the United States, Gish Jen has become a leading literary voice of the Chinese-American experience. In this program, Bill Moyers talks with the critically acclaimed writer, whose novels and short stories are known for their humorous and incisive edge. (14 minutes, color
Gish Jen: Vocation of the Writer (Library Resources)
Get PDFA bibliography of resources available through the Holy Cross Libraries which provide additional information related to Gish Jen: Vocation of the Writer a lecture by award-winning author and speaker Gish Jen. The conference is sponsored by the Rev. Michael C. McFarland, S.J. Center for Religion, Ethics and Culture, the Creative Writing Program, and Asian Studies and was held at the College of the Holy Cross on February 27, 2018.https://crossworks.holycross.edu/bibliography_events/1012/thumbnail.jp
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