Spectral Radiation Properties of a Turbulent Ethylene Pool Fire

2008 ◽  
Author(s):  
Kaushik Biswas ◽  
Yuan Zheng ◽  
Jay Gore
Keyword(s):  
Pool Fires ◽  
Spectral Radiation ◽  
Gaseous Species ◽  
Burner Exit ◽  
Power Spectral ◽  
Radiation Properties ◽  
Power Spectral Densities ◽  
Past Data ◽  
Spectrally Resolved ◽  
Oscillation Frequencies

In the present work, line-of-sight spectral radiation intensities (Iλ) were measured in a 7.1 cm ethylene (C2H4) buoyant diffusion flame, designed to mimic pool fires. Various time series statistics were calculated using the radiation data. Both soot and gaseous species had significant radiation emissions, emphasizing the need for spectrally-resolved radiation measurements. Significant fluctuations were observed in the radiation intensities from the fire, especially at higher elevations and near the flame edges. In addition, root-mean-square (rms) and probability density functions (PDF) of Iλ indicated higher fluctuations in soot compared to gaseous species. Autocorrelations of Iλ showed periodic oscillations due to the puffing phenomenon typically seen in pool fires. The observed oscillation frequencies ranged from 7.47 to 7.86 Hz and are in excellent agreement with empirical correlations based on past data. Characteristic frequencies of these oscillations were also reflected in the power spectral densities (PSD) of Iλ. Based on the measured autocorrelations of Iλ, it was observed that the integral time scales decrease with increasing height above the burner exit, which is expected since mean velocities increase with height due to combustion-induced buoyancy in pool fires and buoyant flames.

Transient Structure and Radiation Properties of Strongly Radiating Buoyant Flames

1992 ◽  
Vol 114 (3) ◽  
pp. 659-665 ◽  
Author(s):  
Y. R. Sivathanu ◽  
J. P. Gore
Keyword(s):  
Probability Density ◽  
Probability Density Functions ◽  
Density Functions ◽  
Spectral Densities ◽  
Spectral Radiation ◽  
Volume Fractions ◽  
Power Spectral ◽  
Radiation Properties ◽  
Power Spectral Densities ◽  
Instantaneous Temperature

Measurements of instantaneous temperature and soot volume fractions based on absorption and emission in highly buoyant turbulent acetylene/air and propylene/air flames are reported. These measurements are used to predict mean, rms, probability density functions, and power spectral densities of spectral radiation intensities along a representative horizontal chord in the flame. The results show the presence of large quantities of relatively cold soot in the vicinity of smaller amounts of hot soot particles. The resulting inhomogeneity in the temperature of soot in the flame leads to negative cross correlations between temperature and soot volume fractions. The treatment of such correlations was found necessary for predicting the observed probability density functions and the power spectral densities of spectral radiation intensities.

Spectral Radiation Properties of Partially Premixed Turbulent Flames

2003 ◽  
Vol 125 (6) ◽  
pp. 1065-1073 ◽  
Author(s):  
Yuan Zheng ◽  
R. S. Barlow ◽  
Jay P. Gore
Keyword(s):  
Reynolds Number ◽  
Turbulent Flames ◽  
Turbulent Jet ◽  
Mean Square ◽  
Autocorrelation Coefficient ◽  
Spectral Radiation ◽  
Length Scales ◽  
Premixed Turbulent Flames ◽  
Power Spectral ◽  
Radiation Properties

Instantaneous spectral radiation intensities of three standard turbulent jet flames were measured and simulated in this study. In the simulation, a recently developed technique was adapted to reconstruct the local integral time and length scales in the flames. The simulated radiation properties, including mean, root mean square, probability density function, power spectral density and autocorrelation coefficient, were generally within 10% of the measurements. The macro time and length scales were found to increase with increasing distance from the axis and the radial averages of these scales were found to increase with down stream distance but decrease with Reynolds number.

Analysis of power spectral densities of electrocardiograms

1971 ◽  
Vol 12 (1-2) ◽  
pp. 41-51 ◽  
Author(s):  
Vrudhula K. Murthy ◽  
L. Julian Haywood ◽  
John Richardson ◽  
Robert Kalaba ◽  
Steven Salzberg ◽  
...  
Keyword(s):  
Spectral Densities ◽  
Power Spectral ◽  
Power Spectral Densities

scholarly journals Delta and Theta waves in Super Consciousness Meditation.

2020 ◽  
Author(s):  
Anil Kumar Bheemaiah
Keyword(s):  
Average Power ◽  
Spectral Densities ◽  
Theta Wave ◽  
Convolutional Networks ◽  
Theta Waves ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Lyapunov Coefficient ◽  
Fmri Time Series ◽  
Power Densities

Study on Kundalini Meditation of Super-conscious Meditation of the Himalayan Tradition and Sahaja Meditation, to determine the average power spectral densities and power ratios of TP9, AF7, AF8, and TP10, electrodes and two ear electrodes on a Muse Headset.These parameters are used to create quantitative criteria to indicate degree of meditation and to create a trigger for bird chirp events.We find an increase in Delta and Theta wave power densities, in the deep meditation state as compared to the initiation and restful states. keywords: Kundalini, super consciousness, neurosky, muse, chakra based meditation, alpha to beta ratio, delta to beta ratio, power spectral densities, differential power spectral densities, fMRi, time series, iD convolutional networks. Lyapunov coefficient

scholarly journals Differences Amplitude Based Improvement of Minimum Variance Distortionless Response Filter

2020 ◽  
Vol 8 (5) ◽  
pp. 1635-1637
Keyword(s):  
A Priori ◽  
Minimum Variance ◽  
Coherent Noise ◽  
Noise Interference ◽  
Power Spectral ◽  
Minimum Variance Distortionless Response ◽  
Power Spectral Densities ◽  
Noisy Signals ◽  
A New Technique ◽  
Priori Information

In this work, the author introduces a new technique for improving the performance of minimum variance distortionless response filter in condition of coherent noise. The proposal algorithm exploits a priori information of differences amplitude to balance power spectral densities of observed noisy signals. The output signal of MVDR filter is then processed by an additional post-filtering, which based speech presence probability to suppress more noise interference and increase quality speech. In experiments using two noisy signal recordings in anechoeic room, the modified MVDR-filter results provides that the suggested algorithm increases speech quality compared to the conventional MVDR filter.

Analysis of earth motions and seismic sources by power spectral density

1969 ◽  
Vol 59 (3) ◽  
pp. 1071-1091
Author(s):  
Dean V. Power
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
High Explosive ◽  
Peak Velocity ◽  
Test Site ◽  
Nevada Test Site ◽  
Spectral Densities ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Velocity Spectra

abstract Ground motion records from six high-explosive cratering events in northeastern Montana, ten contained nuclear explosive events at the Nevada Test Site, and motions of an earth-fill dam during the Gasbuggy underground nuclear explosion in New Mexico were analyzed for power spectral density, peak velocity and velocity spectra. The high-explosive events included four 20-ton single charges at depths of burst which varied between 42 to 57 feet, a 140-ton row charge consisting of three 20-ton and two 40-ton charges at optimum cratering depths of burst, and a 0.5-ton charge at the optimum depth of burst. It was found that at these depths and charge weights an increase in depth of burst resulted in an increase in peak velocities and power-spectral densities as measured at distant points (> 5 km). Power spectral density was found to be approximately proportional to the first power of yield. For this region it was determined that power spectral density varied inversely as radial distance to the 3.55 power. Three analysis techniques—peak velocity, velocity spectra and power spectral density—are compared, and it is shown that power spectral density is the most consistent method when comparing records from different measuring stations. An analysis of power-spectral density measured at one station for the ten events at the Nevada Test Site shows that a significant shift in the frequency of the energy in the seismogram occurs when the source location changes. For events in the Yucca Flat area the peak energy at Mercury was consistently at 1.0 Hz, while for events in the Pahute Mesa area this peak occurs at 2.5 Hz. A comparison of the power spectral densities on and near the Navajo Dam revealed that the natural frequencies and first harmonics of the dam are 1.4, 2.0 and 2.5 Hz in the mode where motion is parallel to the canyon axis. A simple model makes use of these frequencies to calculate a shear-wave velocity of 1130 ft/sec. A method of using power spectral density to measure earthquake magnitudes and measure the yield of underground explosions is proposed.

Using COVID19 as an Opportunity to Measure Seismic Silences and Bring Geoscience Projects to Students

2021 ◽  
Author(s):  
Artash Nath
Keyword(s):  
Northwest Territories ◽  
World Health ◽  
Virtual Classrooms ◽  
Power Spectral ◽  
Essential Services ◽  
Power Spectral Densities ◽  
The World ◽  
Seismic Vibrations ◽  
Health Organization ◽  
Almost All

<p>On 11 March 2020, the World Health Organization declared Covid19 a pandemic. Countries around the world rushed to declare various states of emergencies. Canada also implemented emergency measures to restrict the movements of people including the closure of borders, non-essential services, and schools and offices to slow the spread of Covid19. I used this opportunity to measure changes in seismic vibrations registered in Canada before, during, and after the lockdown due to the slowdown in transportation, economic, and construction activities. I analyzed continuous seismic data for 6 Canadian cities: Calgary and Edmonton (Alberta), Montreal (Quebec), Ottawa, and Toronto (Ontario), and Yellowknife (Northwest Territories). These cities represented the wide geographical spread of Canada. The source of data was seismic stations run by the Canadian National Seismograph Network (CNSN). Python and ObSpy libraries were used to convert raw data into probabilistic power spectral densities. The seismic vibrations in the PPSDs that fell between 4 Hz and 20 Hz were extracted and averaged for every two weeks period to determine the trend of seismic vibrations. The lockdown had an impact on seismic vibrations in almost all the cities I analyzed. The seismic vibrations decreased between 14% - 44% with the biggest decrease in Yellowknife in the Northwest Territories. In the 3 densely populated cities with a population of over 1 million - Toronto, Montreal, and Calgary, the vibrations dropped by over 30%.</p><p>To enable other students to undertake similar projects for their cities, I created a comprehensive online training module using Jupyter notebooks available on Github. Students can learn about seismic vibrations, how to obtain datasets, and analyze and interpret them using Python. They can share their findings with local policymakers so that they become aware of the effectiveness of the lockdown imposed and are better prepared for lockdowns in the future. When we make data and technology accessible, then lockdowns because of pandemics can be an opportunity for students to take up practical geoscience projects from home or virtual classrooms.</p>

A Study of the Pollutant Formation and Spectral Radiation Properties in Ceramic Fiber Radiant Burner

2007 ◽  
Vol 31 (9) ◽  
pp. 790-798
Author(s):  
Yong-Ki Jeong ◽  
Young-Soo Kim ◽  
Dae-Rae Lee ◽  
Dae-Bong Yang ◽  
Jung-Wan Ryu ◽  
...  
Keyword(s):  
Ceramic Fiber ◽  
Spectral Radiation ◽  
Pollutant Formation ◽  
Radiation Properties

scholarly journals EOG feature relevance determination for microsleep detection

2017 ◽  
Vol 3 (2) ◽  
pp. 815-818
Author(s):  
Martin Golz ◽  
Sebastian Wollner ◽  
David Sommer ◽  
Sebastian Schnieder
Keyword(s):  
Cross Correlation ◽  
Feature Reduction ◽  
Support Vector ◽  
Spectral Bands ◽  
Automatic Relevance Determination ◽  
Signal Features ◽  
Power Spectral ◽  
Vector Machines ◽  
Power Spectral Densities ◽  
Feature Relevance

AbstractAutomatic relevance determination (ARD) was applied to two-channel EOG recordings for microsleep event (MSE) recognition. 10 s immediately before MSE and also before counterexamples of fatigued, but attentive driving were analysed. Two type of signal features were extracted: the maximum cross correlation (MaxCC) and logarithmic power spectral densities (PSD) averaged in spectral bands of 0.5 Hz width ranging between 0 and 8 Hz. Generalised learn-ing vector quantisation (GRLVQ) was used as ARD method to show the potential of feature reduction. This is compared to support-vector machines (SVM), in which the feature reduction plays a much smaller role. Cross validation yielded mean normalised relevancies of PSD features in the range of 1.6 - 4.9 % and 1.9 - 10.4 % for horizontal and vertical EOG, respectively. MaxCC relevancies were 0.002 - 0.006 % and 0.002 - 0.06 %, respectively. This shows that PSD features of vertical EOG are indispensable, whereas MaxCC can be neglected. Mean classification accuracies were estimated at 86.6±b 1.3 % and 92.3±b 0.2 % for GRLVQ and SVM, respec-tively. GRLVQ permits objective feature reduction by inclu-sion of all processing stages, but is not as accurate as SVM.

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