709 research outputs found
AiResearch QCGAT engine: Acoustic test results
The noise levels of the quiet, general aviation turbofan (QCGAT) engine were measured in ground static noise tests. The static noise levels were found to be markedly lower than the demonstrably quiet AiResearch model TFE731 engine. The measured QCGAT noise levels were correlated with analytical noise source predictions to derive free-field component noise predictions. These component noise sources were used to predict the QCGAT flyover noise levels at FAR Part 36 conditions. The predicted flyover noise levels are about 10 decibels lower than the current quietest business jets
Computer program to predict noise of general aviation aircraft: User's guide
Program NOISE predicts General Aviation Aircraft far-field noise levels at FAA FAR Part 36 certification conditions. It will also predict near-field and cabin noise levels for turboprop aircraft and static engine component far-field noise levels
Preliminary design study of a quiet, high flow fan (QHF) stage
Concepts selected to reduce fan generated noise in a turbofan are presented. Near-sonic flow at the fan inlet to reduce upstream propagated noise and the use of long-chord vanes to reduce downstream noise is discussed. The near-sonic condition at the rotor inlet plane was achieved by designing for high specific mass flow and by maintaining the high flow at reduced power by variable stators and variable fan exhaust nozzle. The long-chord vanes reduce response to unsteady flow. The acoustic design showed that long-chord stators would significantly reduce turbofan source noise and that other stator design parameters have no appreciable effect on noise for the spacing and chord length of the turbofan design. Four rig flow paths studied in the aerodynamic preliminary design are discussed. Noise prediction results indicate that a turbofan powered aircraft would be under federal air regulations levels without any acoustic treatment
Investigation of the magnesium-silicate raw materials of Ural-Siberian region for ceramic propp ants obtaining
Supervisory Control System Architecture for Advanced Small Modular Reactors
This technical report was generated as a product of the Supervisory Control for Multi-Modular SMR Plants project within the Instrumentation, Control and Human-Machine Interface technology area under the Advanced Small Modular Reactor (SMR) Research and Development Program of the U.S. Department of Energy. The report documents the definition of strategies, functional elements, and the structural architecture of a supervisory control system for multi-modular advanced SMR (AdvSMR) plants. This research activity advances the state-of-the art by incorporating decision making into the supervisory control system architectural layers through the introduction of a tiered-plant system approach. The report provides a brief history of hierarchical functional architectures and the current state-of-the-art, describes a reference AdvSMR to show the dependencies between systems, presents a hierarchical structure for supervisory control, indicates the importance of understanding trip setpoints, applies a new theoretic approach for comparing architectures, identifies cyber security controls that should be addressed early in system design, and describes ongoing work to develop system requirements and hardware/software configurations
Protocol: Exercise interventions to improve back shape/posture, balance, falls, and fear of falling in older adults with hyperkyphosis: A systematic review
The bolometric focal plane array of the Polarbear CMB experiment
The Polarbear Cosmic Microwave Background (CMB) polarization experiment is
currently observing from the Atacama Desert in Northern Chile. It will
characterize the expected B-mode polarization due to gravitational lensing of
the CMB, and search for the possible B-mode signature of inflationary
gravitational waves. Its 250 mK focal plane detector array consists of 1,274
polarization-sensitive antenna-coupled bolometers, each with an associated
lithographed band-defining filter. Each detector's planar antenna structure is
coupled to the telescope's optical system through a contacting dielectric
lenslet, an architecture unique in current CMB experiments. We present the
initial characterization of this focal plane
Development and characterization of the readout system for POLARBEAR-2
POLARBEAR-2 is a next-generation receiver for precision measurements of the
polarization of the cosmic microwave background (Cosmic Microwave Background
(CMB)). Scheduled to deploy in early 2015, it will observe alongside the
existing POLARBEAR-1 receiver, on a new telescope in the Simons Array on Cerro
Toco in the Atacama desert of Chile. For increased sensitivity, it will feature
a larger area focal plane, with a total of 7,588 polarization sensitive
antenna-coupled Transition Edge Sensor (TES) bolometers, with a design
sensitivity of 4.1 uKrt(s). The focal plane will be cooled to 250 milliKelvin,
and the bolometers will be read-out with 40x frequency domain multiplexing,
with 36 optical bolometers on a single SQUID amplifier, along with 2 dark
bolometers and 2 calibration resistors. To increase the multiplexing factor
from 8x for POLARBEAR-1 to 40x for POLARBEAR-2 requires additional bandwidth
for SQUID readout and well-defined frequency channel spacing. Extending to
these higher frequencies requires new components and design for the LC filters
which define channel spacing. The LC filters are cold resonant circuits with an
inductor and capacitor in series with each bolometer, and stray inductance in
the wiring and equivalent series resistance from the capacitors can affect
bolometer operation. We present results from characterizing these new readout
components. Integration of the readout system is being done first on a small
scale, to ensure that the readout system does not affect bolometer sensitivity
or stability, and to validate the overall system before expansion into the full
receiver. We present the status of readout integration, and the initial results
and status of components for the full array.Comment: Presented at SPIE Astronomical Telescopes and Instrumentation 2014:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for
Astronomy VII. Published in Proceedings of SPIE Volume 915
Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations
We present all-sky modelling of the high resolution Planck, IRAS, and WISE
infrared (IR) observations using the physical dust model presented by Draine
and Li in 2007 (DL). We study the performance and results of this model, and
discuss implications for future dust modelling. The present work extends the DL
dust modelling carried out on nearby galaxies using Herschel and Spitzer data
to Galactic dust emission. We employ the DL dust model to generate maps of the
dust mass surface density, the optical extinction Av, and the starlight
intensity parametrized by Umin. The DL model reproduces the observed spectral
energy distribution (SED) satisfactorily over most of the sky, with small
deviations in the inner Galactic disk and in low ecliptic latitude areas. We
compare the DL optical extinction Av for the diffuse interstellar medium with
optical estimates for 2 10^5 quasi-stellar objects (QSOs) observed in the Sloan
digital sky survey. The DL Av estimates are larger than those determined
towards QSOs by a factor of about 2, which depends on Umin. The DL fitting
parameter Umin, effectively determined by the wavelength where the SED peaks,
appears to trace variations in the far-IR opacity of the dust grains per unit
Av, and not only in the starlight intensity. To circumvent the model
deficiency, we propose an empirical renormalization of the DL Av estimate,
dependent of Umin, which compensates for the systematic differences found with
QSO observations. This renormalization also brings into agreement the DL Av
estimates with those derived for molecular clouds from the near-IR colours of
stars in the 2 micron all sky survey. The DL model and the QSOs data are used
to compress the spectral information in the Planck and IRAS observations for
the diffuse ISM to a family of 20 SEDs normalized per Av, parameterized by
Umin, which may be used to test and empirically calibrate dust models.Comment: Final version that has appeared in A&
Alumosilicate ceramic proppants based on natural refractory raw materials
The sintering-strengthening effect of the additions of the highly ferrous bauxite (with Fe[2]O[3] content of 20-25 % in the calcined state) in the compositions with refractory clays was established. It was found that in the temperature range 1350-1500°C the additions of bauxite in amounts of 10-40% have a fluxing effect due to the iron oxide introduced with bauxite in compositions with clay. An increasing the bauxite additive in the amount of 50-70% ensures its strengthening effect by increasing the total content of the mullite of the prismatic habit in the firing products of composites with clay. Preliminary clay and bauxite calcination at 900 °С and an increase in the content of bauxite additive up to 50-70% in compositions with clay allow to produce aluminosilicate proppants with a bulk density of 1.62-1.65 g/сm{3} and compressive strength up to 52 MPa
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