Evaluation of Smoke Detector Response Estimation Methods: Optical Density, Temperature Rise, and Velocity at Alarm

2006 ◽  
Vol 16 (4) ◽  
pp. 251-268 ◽  
Author(s):  
J. A. Geiman ◽  
D. T. Gottuk ◽  
J. A. Milke
Keyword(s):  
Optical Density ◽  
Temperature Rise ◽  
Estimation Methods ◽  
Detector Response ◽  
Smoke Detector

To the Temperature Dependence of Carbon Particle Formation in Shock Wave Pyrolysis Processes

2003 ◽  
Vol 217 (7) ◽  
pp. 893-910 ◽  
Author(s):  
A. Emelianov ◽  
A. Eremin ◽  
H. Jander ◽  
H. Gg. Wagner
Keyword(s):  
Shock Wave ◽  
Optical Density ◽  
Temperature Rise ◽  
Carbon Particle ◽  
Particle Growth ◽  
Particle Formation ◽  
Reflected Shock Wave ◽  
Final Particle ◽  
Reflected Shock ◽  
Particle Yield

AbstractIn this work the results of numerous experiments on carbon particle formation in combustion and pyrolysis of various carbon bearing molecules behind shock waves in the wide temperature range from 1200K to 3500K are analyzed. It is shown, that the discrepancy in the temperatures of the maximum particle yield could be attributed to the differences in the endothermicy of the pyrolysis of various molecules and the maximum optical density at 633nm in all mixtures can be related to the same temperture T=1600K. Based on this consideration, several statements were formulated. First – particle growth in all mixtures can be described by the uniform dependence of optical density D (at 633 nm) on time D~aτ0.4 indicating, that particle formation proceeds via homogeneous condensation. The second – decrease of the optical density at 633nm with the temperature rise is caused not by the decrease of particle yield, but the decrease of their size resulting in the fall of extinction at the given wavelength. Third – the reason of the fall of the final particle size with the temperature rise is the acceleration of the initial cluster formation process and a corresponding increase of the particle number density. And the last statement – the secondary particle growth, observed at T>2200K is completely determined by the primary clusters (nucleus) formed behind the incident wave and the coagulation of small carbon particles formed behind the reflected shock wave using these clusters.

scholarly journals Study on Smoke Detector Characteristics Using Fire Simulations

2021 ◽  
Vol 35 (4) ◽  
pp. 8-14
Author(s):  
Ga-Hyeon Lee ◽  
Sung-Eun Lee ◽  
Si-Kuk Kim ◽  
Seung-Chul Lee
Keyword(s):  
Optical Density ◽  
Preliminary Data ◽  
Performance Testing ◽  
Wood Smoke ◽  
Smoke Detector ◽  
Experimental Conditions ◽  
Smoke Detectors ◽  
Fire Detector ◽  
Technical Specifications ◽  
Fire Experiments

To reduce the damage caused by fire detector malfunctions, we investigated the standards and literature pertaining to fire detectors in Korea. The domestic standards cite UL's technical specifications, which provide only the standards and types of combustible materials; however, additional research is needed because no facilities related to the experiments are investigated and no fire experiments have actually been conducted. In this study, we refer to UL 268, which is similar to the domestic standards, as well as detailed experimental conditions and methods to improve smoke detector performances; we also use wood as the combustion material from among the fire sources specified in UL 268. Experiments were conducted to measure the sensitization rates using an optical density meter and repeated to match the wood smoke profile standard provided in UL 268. Furthermore, we compared the smoke concentrations detected by the smoke detectors in the fire experiments with those from fire simulations using FDS software to confirm the detector characteristics. Through these comparisons, we show that this research could be used as preliminary data for performance testing of detectors using UL 268.

scholarly journals Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments

2018 ◽  
Vol 5 (4) ◽  
pp. 180188 ◽  
Author(s):  
Ran Tu ◽  
Yi Zeng ◽  
Jun Fang ◽  
Yong-Ming Zhang
Keyword(s):  
High Altitude ◽  
Burning Rate ◽  
Ambient Pressure ◽  
Detector Response ◽  
Smoke Detector ◽  
Fire Tests ◽  
Ion Chamber ◽  
Smoke Detectors ◽  
Point Type ◽  
Detector Design

The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5). First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be ‘enhanced’ by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions. Third, to provide a reference for smoke detector design in high-altitude areas, the differences between signal speed in rising and peak values at two locations are discussed. Also, relationship between ion chamber signals and smoke optical densities are presented by utilization of an ionization smoke detector and smoke concentration meter. Moreover, a hierarchical diagram is illustrated to provide a better understanding of the effects of altitude on combustible burning behaviour and the mechanisms of detector response.

Analysis of photographic emulsions for High-Voltage Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 452-453 ◽  
Author(s):  
James R. Kremer ◽  
Paul S. Furcinitti ◽  
Eileen O’Toole ◽  
J. Richard McIntosh
Keyword(s):  
Electron Microscope ◽  
Optical Density ◽  
High Voltage ◽  
Noise Power ◽  
Limited Information ◽  
Modulation Transfer ◽  
Transmission Microscopy ◽  
High Voltage Electron Microscopy ◽  
Voltage Range ◽  
Voltage Electron

Characteristics of electron microscope film emulsions, such as the speed, the modulation transfer function, and the exposure dependence of the noise power spectrum, have been studied for electron energies (80-100keV) used in conventional transmission microscopy. However, limited information is available for electron energies in the intermediate to high voltage range, 300-1000keV. Furthermore, emulsion characteristics, such as optical density versus exposure, for new or improved emulsions are usually only quoted by film manufacturers for 80keV electrons. The need for further film emulsion studies at higher voltages becomes apparent when searching for a film to record low dose images of radiation sensitive biological specimens in the frozen hydrated state. Here, we report the optical density, speed and relative resolution of a few of the more popular electron microscope films after exposure to 1MeV electrons.Three electron microscope films, Kodak S0-163, Kodak 4489, and Agfa Scientia 23D56 were tested with a JEOLJEM-1000 electron microscope operating at an accelerating voltage of 1000keV.

The Impact of Missing and Error-Prone Auxiliary Information on Sparse-Matrix Sub-Population Parameter Estimates

Methodology ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 89-99 ◽  
Author(s):  
Leslie Rutkowski ◽  
Yan Zhou
Keyword(s):  
Sparse Matrix ◽  
Small Body ◽  
Auxiliary Information ◽  
Poor Quality ◽  
Quality Data ◽  
Estimation Methods ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Conditioning Model ◽  
The Impact

Abstract. Given a consistent interest in comparing achievement across sub-populations in international assessments such as TIMSS, PIRLS, and PISA, it is critical that sub-population achievement is estimated reliably and with sufficient precision. As such, we systematically examine the limitations to current estimation methods used by these programs. Using a simulation study along with empirical results from the 2007 cycle of TIMSS, we show that a combination of missing and misclassified data in the conditioning model induces biases in sub-population achievement estimates, the magnitude and degree to which can be readily explained by data quality. Importantly, estimated biases in sub-population achievement are limited to the conditioning variable with poor-quality data while other sub-population achievement estimates are unaffected. Findings are generally in line with theory on missing and error-prone covariates. The current research adds to a small body of literature that has noted some of the limitations to sub-population estimation.

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