Real three-dimensional dynamical VCSEL simulation with spatially distributed noise sources

2005 ◽  
Author(s):  
P. Nyakas ◽  
Z. Puskas ◽  
T. Karpati ◽  
T. Veszpremi ◽  
G. Zsombok ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Noise Sources ◽  
Spatially Distributed

Incorporation of spatial variability in modeling non-point source groundwater nitrate pollution

1996 ◽  
Vol 33 (4-5) ◽  
pp. 233-240 ◽  
Author(s):  
F. S. Goderya ◽  
M. F. Dahab ◽  
W. E. Woldt ◽  
I. Bogardi
Keyword(s):  
Spatial Variability ◽  
Point Source ◽  
Three Dimensional ◽  
Nitrate Contamination ◽  
Geostatistical Simulation ◽  
Chemical Measurements ◽  
Spatially Distributed ◽  
Potential Benefits ◽  
Zone Modeling ◽  
Physical And Chemical

A methodology for incorporation of spatial variability in modeling non-point source groundwater nitrate contamination is presented. The methodology combines geostatistical simulation and unsaturated zone modeling for estimating the amount of nitrate loading to groundwater. Three dimensional soil nitrogen variability and 2-dimensional crop yield variability are used in quantifying potential benefits of spatially distributed nitrogen input. This technique, in combination with physical and chemical measurements, is utilized as a means of illustrating how the spatial statistical properties of nitrate leaching can be obtained for different scenarios of fixed and variable rate nitrogen applications.

Pressure feedback-based blade–vortex interaction noise controller for helicopter rotors

2018 ◽  
Vol 17 (3) ◽  
pp. 295-318 ◽  
Author(s):  
Sara Modini ◽  
Giorgio Graziani ◽  
Giovanni Bernardini ◽  
Massimo Gennaretti
Keyword(s):  
High Harmonic ◽  
Three Dimensional ◽  
Rotor Blades ◽  
Aerodynamic Noise ◽  
Vortex Interaction ◽  
Noise Sources ◽  
Power Requirement ◽  
Blade Vortex Interaction ◽  
Pressure Feedback ◽  
Helicopter Main Rotor

With the aim of alleviating the noise annoyance emitted by blade–vortex interactions occurring on helicopter main rotors, the present work presents a methodology suitable for the identification of a multi-cyclic harmonic controller based on the actuation of rotor blades equipped with Miniature Trailing Edge Effectors. The objective of the control methodology is the direct suppression of the aerodynamic noise sources by generation of localized high-harmonic blade–vortex interaction counter-actions. The set-up of control devices is selected on the basis of the blade–vortex interaction scenario, taking into account a trade-off between effectiveness and power requirement. The control law is efficiently identified by means of an optimal controller synthesized through suitable two-dimensional multi-vortex, parallel blade–vortex interaction problems. The proposed methodology is validated by the application to realistic helicopter main rotors during low-speed descent flights, numerically simulated through high-fidelity aerodynamic and aeroacoustic solvers based, respectively, upon a three-dimensional free-wake boundary element method to solve the potential flow around rotors in blade–vortex interaction conditions and the Farassat 1A formulation. Results concerning the capability of the proposed controller to alleviate the blade–vortex interaction noise emitted by a realistic helicopter main rotor are presented and discussed.

A Review of Active Noise Control Applications on Noise Barrier in Three-Dimensional/Open Space: Myths and Challenges

2019 ◽  
Vol 18 (04) ◽  
pp. 1930002 ◽  
Author(s):  
Hsiao Mun Lee ◽  
Zhaomeng Wang ◽  
Kian Meng Lim ◽  
Heow Pueh Lee
Keyword(s):  
Open Space ◽  
Noise Control ◽  
Active Noise Control ◽  
Three Dimensional ◽  
Construction Site ◽  
Noise Sources ◽  
Current State ◽  
Active Noise ◽  
Noise Barrier ◽  
Passive Noise

Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise problems. However, there are both myths and challenges in its implementations. In a crowded city like Singapore, many noise sources from construction site and subway track are located very close to the residential and commercial buildings. It was suggested by few researchers that by placing suitable control speakers at the construction site (working principle of ANC), the noise from the construction site could be prevented from propagating to the surrounding buildings. Similarly, for viaduct or subway track, by placing control speakers along the viaduct or track, the noise generated by the passing trains or vehicles could be reduced based on the principle of ANC technique. However, implementation of ANC technique on these noise issues is not easy as all of these noise control problems involve multiple noise sources with complex or transient frequency spectrum in large three-dimensional/open space. Therefore, the main intention of the present paper is to discuss the current state of the art of this topic as well as to examine the potential application and limitation of the ANC technique in mitigating unwanted noise, particularly in large three-dimensional/open space and with cooperation of passive noise barrier.

Study on the aerodynamic noise of internal flow of regenerative flow compressors for a fuel-cell car

2013 ◽  
Vol 228 (7) ◽  
pp. 1155-1174 ◽  
Author(s):  
Qiang Kang ◽  
Shuguang Zuo ◽  
Kaijun Wei
Keyword(s):  
Finite Element ◽  
Fuel Cell ◽  
Dynamic Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Internal Flow ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Element Analysis ◽  
Regenerative Flow

The regenerative flow compressor used in fuel-cell cars generates high aerodynamic noise, which is the main source of noise. Compared with the research on centrifugal or axial turbomachinery, research on the noise of regenerative flow compressors is far from adequate. This paper presents the on-going work on it at Tongji University based on both experimental and computational works. In this study, a three-dimensional unsteady computational fluid dynamic model of the compressor was constructed with the large eddy approach. The pressure fluctuation, vortex noise source and Ffowcs William-Hawkings (FW-H) method were used to analyze the characteristics of the aerodynamic noise sources. Additionally, the far-field aerodynamic noise generated by the internal flow of the compressor was predicted using the aeroacoustic finite element method. The simulation results were validated with the experimental data. It was found that combining the fluid dynamic model and aeroacoustic finite element analysis promising results for aerodynamic noise prediction of compressors could be produced. The effects of the impeller parameters on the aerodynamic noise of the compressor were also studied.

Temperature profiles with respect to inhomogeneity and geometry of the human body

1988 ◽  
Vol 65 (3) ◽  
pp. 1110-1118 ◽  
Author(s):  
J. Werner ◽  
M. Buse
Keyword(s):  
Human Body ◽  
Three Dimensional ◽  
The Body ◽  
Physiological Data ◽  
Physical Parameters ◽  
Temperature Profiles ◽  
Metabolic Heat ◽  
Spatially Distributed ◽  
Adequate Representation ◽  
Neutral Conditions

Temperature profiles within the human body are highly dependent on the geometry and inhomogeneity of the body. Physical parameters such as density and heat conductivity of the various tissues and variables such as blood flow and metabolic heat production of different organs are spatially distributed and thereby influence the temperature profiles within the human body. Actual physiological knowledge allows one to take into account up to 54 different spatially distributed values for each parameter. An adequate representation of the anatomy of the body requires a spatial three-dimensional grid of at least 0.5-1.0 cm. This is achieved by photogrammetric treatment of three-dimensional anatomic models of the human body. As a first essential result, the simulation system has produced a realistic picture of the topography of temperatures under neutral conditions. Compatibility of reality and simulation was achieved solely on the basis of physical considerations and physiological data base. Therefore the simulation is suited to the extrapolation of temperature profiles that cannot be obtained experimentally.

scholarly journals Modeling global atmospheric CO<sub>2</sub> with improved emission inventories and CO<sub>2</sub> production from the oxidation of other carbon species

2010 ◽  
Vol 3 (3) ◽  
pp. 889-948 ◽  
Author(s):  
R. Nassar ◽  
D. B. A. Jones ◽  
P. Suntharalingam ◽  
J. M. Chen ◽  
R. J. Andres ◽  
...  
Keyword(s):  
Co2 Emissions ◽  
Inverse Modeling ◽  
Latitudinal Gradient ◽  
Three Dimensional ◽  
Satellite Observations ◽  
Chemical Production ◽  
Spatial And Temporal Distributions ◽  
Spatially Distributed ◽  
Annual Estimate ◽  
Surface Correction

Abstract. The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 simulation with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C/yr), 3-D spatially-distributed emissions from aviation (~0.16 Pg C/yr), and 3-D chemical production of CO2 (~1.05 Pg C/yr). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of carbon precursor as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May–June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (~10%) with a complex spatial structure generally resulting in decreased CO2 over land and increased CO2 over the oceans. Since these CO2 emissions are omitted or misrepresented in most inverse modeling work to date, their implementation in forward simulations should lead to improved inverse modeling estimates of terrestrial biospheric fluxes.

scholarly journals Measuring Three-Dimensional Temperature Distributions in Steel–Concrete Composite Slabs Subjected to Fire Using Distributed Fiber Optic Sensors

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5518
Author(s):  
Yi Bao ◽  
Matthew S. Hoehler ◽  
Christopher M. Smith ◽  
Matthew Bundy ◽  
Genda Chen
Keyword(s):  
Fiber Optic ◽  
Three Dimensional ◽  
Thermal Response ◽  
Point Clouds ◽  
Fiber Optic Sensors ◽  
Distributed Sensors ◽  
Temperature Distributions ◽  
Composite Slabs ◽  
Spatially Distributed ◽  
Dense Point

Detailed information about temperature distribution can be important to understand structural behavior in fire. This study develops a method to image three-dimensional temperature distributions in steel–concrete composite slabs using distributed fiber optic sensors. The feasibility of the method is explored using six 1.2 m × 0.9 m steel–concrete composite slabs instrumented with distributed sensors and thermocouples subjected to fire for over 3 h. Dense point clouds of temperature in the slabs were measured using the distributed sensors. The results show that the distributed sensors operated at material temperatures up to 960 °C with acceptable accuracy for many structural fire applications. The measured non-uniform temperature distributions indicate a spatially distributed thermal response in steel–concrete composite slabs, which can only be adequately captured using approaches that provide a high density of through-depth data points.

Three-Dimensional Non-Multi-Gaussian Simulation by Including Multiple Types of Information at Non-Colocated Locations

2021 ◽  
Author(s):  
Claus Haslauer ◽  
Bo Xiao ◽  
András Bárdossy ◽  
Olaf Cirpka ◽  
Geoffrey Bohling
Keyword(s):  
Hydraulic Conductivity ◽  
Data Fusion ◽  
Three Dimensional ◽  
Tracer Tests ◽  
Geostatistical Simulation ◽  
Dependence Structure ◽  
Large Set ◽  
Stochastic Hydrogeology ◽  
Spatially Distributed ◽  
Types Of Information

&lt;div&gt; &lt;p&gt;&lt;span&gt;The incentive of this presentation is the age-old quest of stochastic hydrogeology: Are we able to better match observed long-tailed breakthrough curves by an improved description of the spatial dependence of saturated hydraulic conductivity (&lt;em&gt;K&lt;/em&gt;)?&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;This contribution considers two innovations: We include more information than usual by incorporating multiple types of observations at non-collocated locations (&lt;em&gt;data fusion&lt;/em&gt;), and we extract more information than usual from the available measurements by analysing statistical properties that go further than typical second-order moments-based analyses (&lt;em&gt;non-Gaussian geostatistics&lt;/em&gt;).&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;The evaluation of these innovations in geostatistical simulation methodologies of spatially distributed &amp;#64257;elds of &lt;em&gt;K&lt;/em&gt; is performed against real-world tracer-tests that were performed at the site of the &lt;em&gt;K&lt;/em&gt; measurements. The hypothesis is that &amp;#64257;elds that contain the most information match the observed solute spreading best.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;The spatially distributed &lt;em&gt;K&lt;/em&gt;- &amp;#64257;elds were geostatistically simulated using the multi-objective phase annealing (&lt;em&gt;PA&lt;/em&gt;) method. To accelerate the asymmetry updating during the PA iterations, a Fourier transform based algorithm is integrated into the three-dimensional PA method. Multiple types of objective functions are included to match the value and/or the order of observations as well as the degree of the &amp;#8220;non-Gausianness&amp;#8221; (asymmetry). Additionally, &amp;#8220;censored measurements&amp;#8221; (e.g., high-K measurements above the sensitivity of the device that measures &lt;em&gt;K&lt;/em&gt;) are considered.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;The MAcroDispersion Experiment (MADE) site is considered the holy grail of stochastic hydrogeology as among the well instrumented sites in the world, the variance of the hydraulic conductivity measurements at the MADE site is fairly large and detailed observations of solute spreading are available. In addition to the classic &lt;em&gt;K&lt;/em&gt;-measurements obtained via 2611 &amp;#64258;owmeter measurements, recently a large set of 31123 &lt;em&gt;K&lt;/em&gt;&amp;#8209;measurements obtained via direct push injection logging (DPIL), are available, although not at the same locations where the &amp;#64258;owmeter measurements were taken.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;The in&amp;#64258;uence of including di&amp;#64256;erent types of information on the simulated spatially-distributed &amp;#64257;elds of &lt;em&gt;K&lt;/em&gt; are evaluated by analyzing the ensemble spatial moments and the dispersivity of numerical conservative solute tracer tests performed using particle tracking. The improved dependence structure of &lt;em&gt;K&lt;/em&gt; with all of the above knowledge contains more information than &amp;#64257;elds simulated by traditional geostatistical algorithms and expected as a more realistic realization of &lt;em&gt;K&lt;/em&gt; at the MADE site and at many other sites where such data-fusion approaches are necessary.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;

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