4,868 research outputs found
An investigation into fan broadband noise due to rotor-stator interaction
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
Decomposition of modal acoustic power due to cascade–turbulence interaction
No full textThis paper investigates the modal acoustic power (MAP) generated by a cascade of flat-plate airfoils interacting with homogeneous, isotropic turbulence. The basic formulation for the upstream and downstream acoustic power based on the analytical theory of Smith [Discrete frequency sound generation in axial flow turbomachines, Reports and Memoranda no. 3709, Aeronautical Research Council, 1972] and its generalization to broadband noise due to Cheong et al. [High frequency formulation for the acoustic power spectrum due to cascade–turbulence interaction. Journal of the Acoustical Society of America 119 (2006) 108–122]. The MAP has been expressed as the sum of cut-on acoustic modes, whose modal power is the product of three terms: a term that specifies the wavenumber distribution of mean square velocity, a sound power factor that specifies the efficiency of radiation, and an acoustic blade response function. The effect of these terms on the MAP is discussed in detail in this paper. The acoustic blade response functions are found to determine the modal lines of minimum sound power in mode-frequency maps of the MAP. The upstream sound power factor is less than the downstream power factor, which is generally large, especially away from the cut-off frequency. Both power factors are small for modes close to cut-off. Modes close to cut-off, therefore, do not contribute significantly to the radiated acoustic power in the downstream direction, even though the modal pressure amplitude for these modes is high since they are excited close to resonance. For an isotropic turbulent gust, the mean square velocity wave number spectrum reduces only the magnitude of the MAP without altering the distribution of power in the frequency-mode map<br/
Education and Training in St. Vincent and the Grenadines: A Partially Annotated Bibliography
No full textThis bibliography on “Education and Training in St. Vincent and the Grenadines” has been specifically prepared for the UWI School of Continuing Studies’ St. Vincent and the Grenadines Conference. It covers all aspects of education and training in St. Vincent and the Grenadines including: Academic achievement,economics of education, educational infrastructure, literacy and mathematics education
Aerodynamic noise from a train pantograph
No full textMany studies have shown that when the speed of high speed trains exceeds around 300km/h, aerodynamic noise becomes the most significant noise source. The pantograph, or current collector, is mounted on the top of the train and is therefore not shielded by noise barriers. This study is focused on pantograph noise reduction using a computational approach. Due to the complex geometry of the pantograph and the fact that it is composed of a number of slender bodies, a component-based approach is adopted to ensure the feasibility of numerical simulations. Computational Fluid Dynamics calculations are carried out using a DDES model.The far-field noise is calculated by using the Ffowcs Williams-Hawkings equation based upon the aerodynamic characteristics obtained in the near-field by the CFD model. The investigation concentrates on the sound generated by a circular cylinder, typical of the pantograph,in cross-flow with various speeds and yaw angles. The simulated aerodynamic results give a commendable agreement with experimental results
Dataset for paper "Reduction of aerodynamic noise from square bars by introducing spanwise waviness"
No full textDataset supports:
Liu, X., et al (2018). Reduction of aerodynamic noise from square bars by introducing spanwise waviness. Journal of Sound and Vibration.</span
Investigation of rotor wake turbulence through cyclostationary spectral analysis
No full textThe present paper introduces cyclostationary spectral analysis as a new approach to analyze the turbulence
velocity measurements generated by a rotor. To apply this technique, a random signal should have periodic statistical
characteristics and should be suitable for many rotating mechanical system as shown in recent studies. However,
this method has never been applied on rotor velocity measurements. Via a Wigner–Ville representation, the
instantaneous power spectra of the turbulence in the wakes and in between the wakes will be depicted and analyzed.
The usefulness of the technique applied to rotor-generated turbulence is that it can separate the spectrum of the
turbulence in between the wakes from that in the wake with a much greater frequency resolution than conventional
spectral analysis
Norman Vincent Peale portrait
No full textPortrait of author and minister Norman Vincent Peale, ca. 1984. Peale was born on May 31, 1898, in Bowersville, Ohio. He graduated from Ohio Wesleyan University and became one of the most influential ministers of the twentieth century, known for his dynamic and energetic sermons. He preached an optimistic message that many Americans accepted during such trying events as the Great Depression, World War II, the Cold War, and the Civil Rights Movement. His sermons were broadcast on the radio and shown on television all across the United States. Peale also published forty-six books, his most popular being "The Power of Positive Thinking.
François Vincent
No full textGrandbois introduces Vincent's paintings and prints from 1992 to 1998, analysing the artist's main source of inspiration - the body - while describing his use of the three studios he frequents. Includes a text by Vincent on humour in art. Texts in English, French and Japanese. Biographical notes on artist and author
Kara Gust interviews author Jeff Vande Zande
No full textAuthor Jeff Vande Zande talks about teaching and writing, poems vs. short stories, developing characters in his stories based on his personal experience, and his current projects. Vande Zande is interviewed by Michigan State University Librarian Kara Gust for the MSU Libraries' Michigan Writer Series
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