On the “In-Situ” Control of Acoustic Liner Attenuation

1977 ◽  
Vol 99 (1) ◽  
pp. 63-70 ◽  
Author(s):  
P. D. Dean
Keyword(s):  
Acoustic Impedance ◽  
Test Facility ◽  
Small Scale ◽  
In Situ Control ◽  
Acoustic Liner ◽  
Flow Duct

In this paper a concept is presented which enables the attenuation of sound in a lined duct to be controlled via the control of the fundamental liner characteristic (the acoustic impedance). The concept is described and modeled by a semiempirical analysis. The feasibility is demonstrated by means of measurements of attenuation and local impedance in a small scale flow duct test facility.

scholarly journals Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Hiroshi Kobayashi ◽  
Schunichi Ozaki ◽  
Makoto Yokochi
Keyword(s):  
Noise Reduction ◽  
Acoustic Impedance ◽  
High Speed ◽  
Impedance Control ◽  
Test Facility ◽  
Fan Noise ◽  
Acoustic Liner ◽  
Trial Basis ◽  
Fan Speed ◽  
Control Technologies

This paper describes the development of adaptive acoustic impedance control (AAC) technologies to achieve a larger fan noise reduction, by adaptively adjusting reactance and resistance of the acoustic liner impedance. For the actual proof of the AAC technology III performance, the advanced fan noise absorption control duct liner II was made on trial basis, with the simple control system and the plain device. And, then, the duct liner II was examined for the AAC technology I, II, and III models, using the high speed fan test facility. The test results made clear that the duct liner II of the AAC technology III model could achieve the fan noise reduction higher than O.A. SPL 10 dB (A) at the maximum fan speed 6000 rpm, containing the reduction of fundamental BPF tone of 18 dB and 2nd BPF tone of 10 dB in response to the fan peed change from 3000 to 6000 rpm.

scholarly journals Upscaling THM modeling from small-scale to full-scale in-situ experiments in the Callovo-Oxfordian claystone

2021 ◽  
Vol 144 ◽  
pp. 104582
Author(s):  
D.M. Seyedi ◽  
C. Plúa ◽  
M. Vitel ◽  
G. Armand ◽  
J. Rutqvist ◽  
...  
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
In Situ Experiments

scholarly journals Electrochemical bubble generation via hydrazine oxidation for the in situ control of an electrodeposited conducting polymer micro/-nanostructure

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 11020-11025
Author(s):  
David Possetto ◽  
Luciana Fernández ◽  
Gabriela Marzari ◽  
Fernando Fungo
Keyword(s):  
Conducting Polymer ◽  
Electrochemical Method ◽  
Bubble Generation ◽  
Hydrazine Oxidation ◽  
In Situ Control

An electrochemical method to manipulate the size and density of electrodeposited polypyrrole structures at the micro-nanoscale by the discharge of hydrazine.

In-situ control of on-chip angstrom gaps, atomic switches, and molecular junctions by light irradiation

Nano Today ◽  
2021 ◽  
Vol 39 ◽  
pp. 101226
Author(s):  
Surong Zhang ◽  
Chenyang Guo ◽  
Lifa Ni ◽  
Kerstin M. Hans ◽  
Weiqiang Zhang ◽  
...  
Keyword(s):  
Molecular Junctions ◽  
Light Irradiation ◽  
In Situ Control ◽  
On Chip

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

Preliminary Evaluation of the 24 Ft. Diameter Fan Performance In the MinWaterCSP Large Cooling Systems Test Facility

2021 ◽  
Author(s):  
S. J. van der Spuy ◽  
D. N. J. Els ◽  
L. Tieghi ◽  
G. Delibra ◽  
A. Corsini ◽  
...  
Keyword(s):  
Scaling Laws ◽  
Static Pressure ◽  
Cooling System ◽  
Pressure Rise ◽  
Full Scale ◽  
Test Facility ◽  
Small Scale ◽  
Preliminary Evaluation ◽  
Cfd Analysis ◽  
Setting Angle

Abstract The MinWaterCSP project was defined with the aim of reducing the cooling system water consumption and auxiliary power consumption of concentrating solar power (CSP) plants. A full-scale, 24 ft (7.315 m) diameter model of the M-fan was subsequently installed in the Min WaterCSP cooling system test facility, located at Stellenbosch University. The test facility was equipped with an in-line torque arm and speed transducer to measure the power transferred to the fan rotor, as well as a set of rotating vane anemometers upstream of the fan rotor to measure the air volume flow rate passing through the fan. The measured results were compared to those obtained on the 1.542 m diameter ISO 5801 test facility using the fan scaling laws. The comparison showed that the fan power values correlated within +/− 7% to those of the small-scale fan, but at a 1° higher blade setting angle for the full-scale fan. To correlate the expected fan static pressure rise, a CFD analysis of the 24 ft (7.315 m) diameter fan installation was performed. The predicted fan static pressure rise values from the CFD analysis were compared to those measured on the 1.542 m ISO test facility, for the same fan. The simulation made use of an actuator disc model to represent the effect of the fan. The results showed that the predicted results for fan static pressure rise of the installed 24 ft (7.315 m) diameter fan correlated closely (smaller than 1% difference) to those of the 1.542 m diameter fan at its design flowrate but, once again, at approximately 1° higher blade setting angle.

scholarly journals In Situ control and modification of the probe magnetization state for accurate magnetic force microscopy

2017 ◽  
Author(s):  
Livia Angeloni ◽  
Daniele Passeri ◽  
Marco Natali ◽  
Melania Reggente ◽  
Emanuele Anelli ◽  
...  
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Force Microscopy ◽  
Magnetization State ◽  
In Situ Control

scholarly journals On the short-term variability of turbulence and temperature in the winter mesosphere

2018 ◽  
Vol 36 (4) ◽  
pp. 1099-1116
Author(s):  
Gerald A. Lehmacher ◽  
Miguel F. Larsen ◽  
Richard L. Collins ◽  
Aroh Barjatya ◽  
Boris Strelnikov
Keyword(s):  
Attitude Control ◽  
Large Scale ◽  
Lower Thermosphere ◽  
Density Fluctuations ◽  
Large Temperature ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Temperature Structure ◽  
Wind Shears

Abstract. Four mesosphere–lower thermosphere temperature and turbulence profiles were obtained in situ within ∼30 min and over an area of about 100 by 100 km during a sounding rocket experiment conducted on 26 January 2015 at Poker Flat Research Range in Alaska. In this paper we examine the spatial and temporal variability of mesospheric turbulence in relationship to the static stability of the background atmosphere. Using active payload attitude control, neutral density fluctuations, a tracer for turbulence, were observed with very little interference from the payload spin motion, and with high precision (<0.01 %) at sub-meter resolution. The large-scale vertical temperature structure was very consistent between the four soundings. The mesosphere was almost isothermal, which means more stratified, between 60 and 80 km, and again between 88 and 95 km. The stratified regions adjoined quasi-adiabatic regions assumed to be well mixed. Additional evidence of vertical transport and convective activity comes from sodium densities and trimethyl aluminum trail development, respectively, which were both observed simultaneously with the in situ measurements. We found considerable kilometer-scale temperature variability with amplitudes of 20 K in the stratified region below 80 km. Several thin turbulent layers were embedded in this region, differing in width and altitude for each profile. Energy dissipation rates varied between 0.1 and 10 mW kg−1, which is typical for the winter mesosphere. Very little turbulence was observed above 82 km, consistent with very weak small-scale gravity wave activity in the upper mesosphere during the launch night. On the other hand, above the cold and prominent mesopause at 102 km, large temperature excursions of +40 to +70 K were observed. Simultaneous wind measurements revealed extreme wind shears near 108 km, and combined with the observed temperature gradient, isolated regions of unstable Richardson numbers (0<Ri<0.25) were detected in the lower thermosphere. The experiment was launched into a bright auroral arc under moderately disturbed conditions (Kp∼5).

scholarly journals Microwave snow emission modeling uncertainties in boreal and subarctic environments

2015 ◽  
Vol 9 (5) ◽  
pp. 5719-5773
Author(s):  
A. Roy ◽  
A. Royer ◽  
O. St-Jean-Rondeau ◽  
B. Montpetit ◽  
G. Picard ◽  
...  
Keyword(s):  
Grain Size ◽  
Spatial Variability ◽  
Boreal Forest ◽  
Frozen Soil ◽  
Microwave Emission ◽  
Small Scale ◽  
Radiometric Measurements ◽  
Snow Properties ◽  
Modeling Uncertainties

Abstract. This study aims to better understand and quantify the uncertainties in microwave snow emission models using the Dense Media Radiative Theory-Multilayer model (DMRT-ML) with in situ measurements of snow properties. We use surface-based radiometric measurements at 10.67, 19 and 37 GHz in boreal forest and subarctic environments and a new in situ dataset of measurements of snow properties (profiles of density, snow grain size and temperature, soil characterization and ice lens detection) acquired in the James Bay and Umijuaq regions of Northern Québec, Canada. A snow excavation experiment – where snow was removed from the ground to measure the microwave emission of bare frozen ground – shows that small-scale spatial variability in the emission of frozen soil is small. Hence, variability in the emission of frozen soil has a small effect on snow-covered brightness temperature (TB). Grain size and density measurement errors can explain the errors at 37 GHz, while the sensitivity of TB at 19 GHz to snow increases during the winter because of the snow grain growth that leads to scattering. Furthermore, the inclusion of observed ice lenses in DMRT-ML leads to significant improvements in the simulations at horizontal polarization (H-pol) for the three frequencies (up to 20 K of root mean square error). However, the representation of the spatial variability of TB remains poor at 10.67 and 19 GHz at H-pol given the spatial variability of ice lens characteristics and the difficulty in simulating snowpack stratigraphy related to the snow crust. The results also show that for ground-based radiometric measurements, forest emission reflected by the surface leads to TB underestimation of up to 40 K if neglected. We perform a comprehensive analysis of the components that contribute to the snow-covered microwave signal, which will help to develop DMRT-ML and to improve the required field measurements. The analysis shows that a better consideration of ice lenses and snow crusts is essential to improve TB simulations in boreal forest and subarctic environments.

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