17,185 research outputs found
Physical and subjective studies of aircraft interior noise and vibration
Measurements to define and quantify the interior noise and vibration stimuli of aircraft are reviewed as well as field and simulation studies to determine the subjective response to such stimuli, and theoretical and experimental studies to predict and control the interior environment. In addition, ride quality criteria/standards for noise, vibration, and combinations of these stimuli are discussed in relation to the helicopter cabin environment. Data on passenger response are presented to illustrate the effects of interior noise and vibration on speech intelligibility and comfort of crew and passengers. The interactive effects of noise with multifrequency and multiaxis vibration are illustrated by data from LaRC ride quality simulator. Constant comfort contours for various combinations of noise and vibration are presented and the incorporation of these results into a user-oriented model are discussed. With respect to aircraft interior noise and vibration control, ongoing studies to define the near-field noise, the transmission of noise through the structure, and the effectiveness of control treatments are described
Active vibration isolator for flexible bodies Patent
Vibration control of flexible bodies in steady accelerating environmen
Improved active vibration isolator
Active vibration isolator simultaneously isolates a flexible structure or payload from disturbances, attenuates the response of a flexible structure to transient disturbances, and maintains the equilibrium position of the payload within predetermined limits over a wide range of steady loads and accelerators
Exploratory study of silicide, aluminide, and boride coatings for nitridation-oxidation protection of chromium alloys
Protective coatings for chromium alloys for use in advanced air breathing application
Why Two Renormalization Groups are Better than One
The advantages of using more than one renormalization group (RG) in problems
with more than one important length scale are discussed. It is shown that: i)
using different RG's can lead to complementary information, i.e. what is very
difficult to calculate with an RG based on one flow parameter may be much more
accessible using another; ii) using more than one RG requires less physical
input in order to describe via RG methods the theory as a function of its
parameters; iii) using more than one RG allows one to solve problems with more
than one diverging length scale. The above points are illustrated concretely in
the context of both particle physics and statistical physics using the
techniques of environmentally friendly renormalization. Specifically, finite
temperature theory, an Ising-type system in a film geometry, an
Ising-type system in a transverse magnetic field, the QCD coupling constant at
finite temperature and the crossover between bulk and surface critical
behaviour in a semi-infinite geometry are considered.Comment: 17 pages LaTex; to be published in the Proceedings of RG '96, Dubn
Sonic-boom research: Selected bibliography with annotation
Citations of selected documents are included which represent the state of the art of technology in each of the following subject areas: prediction, measurement, and minimization of steady-flight sonic booms; prediction and measurement of accelerating-flight sonic booms; sonic-boom propagation; the effects of sonic booms on people, communities, structures, animals, birds, and terrain; and sonic-boom simulator technology. Documents are listed in chronological order in each section of the paper, with key documents and associated annotation listed first. The sources are given along with acquisition numbers, when available, to expedite the acquisition of copies of the documents
Trends in Langley helicopter noise research
A broad perspective of needs in helicopter exterior and interior control is presented. Emphasis is given to those items which support noise certification of civil helicopters and which result in reduced environmental noise impact to community residents as well as to helicopter passengers. The activities described are related to the Langley responsibilities for helicopter acoustics as defined by NASA roles and missions
Preparation, analysis and release of simulated interplanetary grains into low Earth orbit
Astronomical observations which reflect the optical and dynamical properties of interstellar and interplanetary grains are the primary means of identifying the shape, size, and the chemistry of extraterrestrial grain materials. Except for recent samplings of extraterrestrial particles in near-Earth orbit and in the stratosphere observations were the only method of deducing the properties of extraterrestrial particles. In order to elucidate the detailed characteristics of observed dust, the observations must be compared with theoretical studies, some of which are discussed in this volume, or compared with terrestrial laboratory experiments. The formation and optical characterization of simulated interstellar and interplanetary dust with particular emphasis on studying the properties on irregularly shaped particles were discussed. Efforts to develop the techniques to allow dust experiments to be carried out in low-Earth orbit were discussed, thus extending the conditions under which dust experiments may be performed
- …