High speed turboprop aeroacoustic study (single rotation). Volume 1: Model development

A frequency-domain noncompact-source theory for the steady loading and volume-displacement (thickness) noise of high speed propellers has been developed and programmed. Both near field and far field effects have been considered. The code utilizes blade surface pressure distributions obtained from three-dimensional nonlinear aerodynamic flow field analysis programs as input for evaluating the steady loading noise. Simplified mathematical models of the velocity fields induced at the propeller disk by nearby wing and fuselage surfaces and by angle-of-attack operation have been developed to provide estimates of the unsteady loading imposed on the propeller by these potential field type interactions. These unsteady blade loadings have been coupled to a chordwise compact propeller unsteady loading noise model to provide predictions of unsteady loading noise caused by these installation effects. Finally, an analysis to estimate the corrections to be applied to the free-field noise predictions in order to arrive at the measurable fuselage sound pressure levels has been formulated and programmed. This analysis considers the effects of fuselage surface reflection and diffraction together with surface boundary layer refraction. The steady loading and thickness model and the unsteady loading model have been verified using NASA-supplied data for the SR-2 and SR-3 model propfans. In addition, the steady loading and thickness model has been compared with data from the SR-6 model propfan. These theoretical models have been employed in the evaluation of the SR-7 powered Gulfstream aircraft in terms of noise characteristics at representative takeoff, cruise, and approach operating conditions. In all cases, agreement between theory and experiment is encouraging

High speed turboprop aeroacoustic study (counterrotation). Volume 1: Model development

The isolated counterrotating high speed turboprop noise prediction program was compared with model data taken in the GE Aircraft Engines Cell 41 anechoic facility, the Boeing Transonic Wind Tunnel, and in NASA-Lewis' 8x6 and 9x15 wind tunnels. The predictions show good agreement with measured data under both low and high speed simulated flight conditions. The installation effect model developed for single rotation, high speed turboprops was extended to include counterotation. The additional effect of mounting a pylon upstream of the forward rotor was included in the flow field modeling. A nontraditional mechanism concerning the acoustic radiation from a propeller at angle of attach was investigated. Predictions made using this approach show results that are in much closer agreement with measurement over a range of operating conditions than those obtained via traditional fluctuating force methods. The isolated rotors and installation effects models were combines into a single prediction program, results of which were compared with data taken during the flight test of the B727/UDF engine demonstrator aircraft. Satisfactory comparisons between prediction and measured data for the demonstrator airplane, together with the identification of a nontraditional radiation mechanism for propellers at angle of attack are achieved

High speed turboprop aeroacoustic study (counterrotation). Volume 2: Computer programs

The isolated counterrotating high speed turboprop noise prediction program developed and funded by GE Aircraft Engines was compared with model data taken in the GE Aircraft Engines Cell 41 anechoic facility, the Boeing Transonic Wind Tunnel, and in the NASA-Lewis 8 x 6 and 9 x 15 wind tunnels. The predictions show good agreement with measured data under both low and high speed simulated flight conditions. The installation effect model developed for single rotation, high speed turboprops was extended to include counter rotation. The additional effect of mounting a pylon upstream of the forward rotor was included in the flow field modeling. A nontraditional mechanism concerning the acoustic radiation from a propeller at angle of attack was investigated. Predictions made using this approach show results that are in much closer agreement with measurement over a range of operating conditions than those obtained via traditional fluctuating force methods. The isolated rotors and installation effects models were combined into a single prediction program. The results were compared with data taken during the flight test of the B727/UDF (trademark) engine demonstrator aircraft

Will England’s universities and students embrace lifelong learning?

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Free carrier effects in gallium nitride epilayers: the valence band dispersion

The dispersion of the A-valence-band in GaN has been deduced from the observation of high-index magneto-excitonic states in polarised interband magneto-reflectivity and is found to be strongly non-parabolic with a mass in the range 1.2-1.8 m_{e}. It matches the theory of Kim et al. [Phys. Rev. B 56, 7363 (1997)] extremely well, which also gives a strong k-dependent A-valence-band mass. A strong phonon coupling leads to quenching of the observed transitions at an LO-phonon energy above the band gap and a strong non-parabolicity. The valence band was deduced from subtracting from the reduced dispersion the electron contribution with a model that includes a full treatment of the electron-phonon interaction.Comment: Revtex, 4 pages, 5 figure

A tale of two objectives: The challenge of meeting diverse targets in UK Business School

Business Schools in Great Britain are currently facing a number of major challenge due to the conflicting objectives that need to be met. The movement towards a metric-driven, performative approach that has occurred in the last decade has meant that the need to meet set measures that focus on the outcomes of students’ study have become imperative. However, focusing solely on these outcomes neglects a second set of objectives that relate to the journey students take during their studies. The need to ensure that both the process and the outcome of students’ studies are stressed is particularly challenging in British Business Schools which are often characterised by a large and diverse student and staff population. This think piece posits that by using a loose/tight cultural approach alongside a Schrödinger's leadership style, leaders can mitigate some of the challenges that are currently faced in the sector

But what do the numbers say? How the movement towards datafication might change English higher education

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Nature as a 'Lifeline': The Power of Photography when Exploring the Experiences of Older Adults living with Memory Loss and Memory Concerns.

The visual is an underutilised modality through which to investigate experiences of memory loss in older people. We describe a visual ethnography with older adults experiencing subjective or objective memory loss, receiving a cognitive wellbeing group intervention designed to prevent cognitive decline and dementia (APPLE-Tree programme). We aimed to explore lived experiences of people with memory concerns, how participants engaged with this photography and co-design project, and how collaboration with an artist/photographer enhanced this process. Nineteen participants shared photographs reflecting what they valued in their daily lives, their experiences of memory concerns, and the intervention. Fourteen participated in qualitative photo-elicitation interviews, and thirteen collaborated with a professional artist/photographer to co-create an exhibition, in individual meetings and workshops, during which a researcher took ethnographic field notes. Eight participants were re-interviewed after the exhibition launch. We contextualise images produced by participants in relation to discourses around the visual and ageing and highlight their relationship with themes developed through thematic analysis that interconnects photographic, observational and interview data. We present themes around the use of photographs to: (1) celebrate connections to nature as a lifeline; (2) anchor lives within the context of relationships with family; (3) reflect on self and identity, enduring through ageing, memory concerns, pandemic, and ageing stereotypes. We explore visual research as a powerful tool for eliciting meaningful accounts from older adults experiencing cognitive change and to connect the arts and social sciences within ageing studies