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Journal ArticleDOI

Risk-based spacecraft fire safety experiments

01 Jan 1995-Reliability Engineering & System Safety (Elsevier)-Vol. 49, Iss: 3, pp 275-291
TL;DR: In this paper, the scenario approach of risk assessment is used to identify modeling needs and, in turn, experiments that would aid in the development of models that would meet these needs.
About: This article is published in Reliability Engineering & System Safety.The article was published on 1995-01-01 and is currently open access. It has received 16 citations till now.
Citations
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Journal ArticleDOI
TL;DR: This article presents a methodology for the identification and prioritization of vulnerabilities in infrastructures and employs graph theory to identify the candidate vulnerable scenarios and produces a prioritized list of vulnerabilities.
Abstract: The extreme importance of critical infrastructures to modern society is widely recognized. These infrastructures are complex and interdependent. Protecting the critical infrastructures from terrorism presents an enormous challenge. Recognizing that society cannot afford the costs associated with absolute protection, it is necessary to identify and prioritize the vulnerabilities in these infrastructures. This article presents a methodology for the identification and prioritization of vulnerabilities in infrastructures. We model the infrastructures as interconnected digraphs and employ graph theory to identify the candidate vulnerable scenarios. These scenarios are screened for the susceptibility of their elements to a terrorist attack, and a prioritized list of vulnerabilities is produced. The prioritization methodology is based on multiattribute utility theory. The impact of losing infrastructure services is evaluated using a value tree that reflects the perceptions and values of the decisionmaker and the relevant stakeholders. These results, which are conditional on a specified threat, are provided to the decisionmaker for use in risk management. The methodology is illustrated through the presentation of a portion of the analysis conducted on the campus of the Massachusetts Institute of Technology.

286 citations


Additional excerpts

  • ...(11) They have also been used to identify research needs.(12) Reference 2 recommends that this approach be used for terrorist threats and that it serve as the basis for risk management....

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Proceedings ArticleDOI
12 Jul 1999
TL;DR: In this paper, material flammability and fire spread in microgravity are significantly affected by atmospheric flow rate, oxygen concentration, and diluent composition, which can lead to modifications and correlations to standard material assessment tests for prediction of fire resistance in space.
Abstract: Research in microgravity (low-gravity) combustion promises innovations and improvements in fire prevention and response for human-crew spacecraft. Findings indicate that material flammability and fire spread in microgravity are significantly affected by atmospheric flow rate, oxygen concentration, and diluent composition. This information can lead to modifications and correlations to standard material-assessment tests for prediction of fire resistance in space. Research on smoke-particle changes in microgravity promises future improvements and increased sensitivity of smoke detectors in spacecraft. Research on fire suppression by extinguishing agents and venting can yield new information on effective control of the rare, but serious fire events in spacecraft.

41 citations


Cites background from "Risk-based spacecraft fire safety e..."

  • ...6), most likely because the lack of convective movement favors the agglomeration of individual particles [55]....

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Journal ArticleDOI
TL;DR: In this article, the effect of electric current on the ignition and flame propagation propensity of polyethylene-insulated copper conductor electrical wire is investigated. And the results of an experimental and numerical study of the effects of electric currents on the flame propagation velocity and the current of wire are presented.
Abstract: This paper describes the results of an experimental and numerical study of the effect of electric current on the ignition and flame propagation propensity of polyethylene-insulated copper conductor electrical wire Two simplified models were developed to describe the ignition and steady flame propagation of energized electrical wires exposed to an external heat flux, respectively The models predict that for a higher-conductance wire it is more difficult to achieve ignition and flame propagation Experiments were performed on three types of electrical wires with different conductor diameter of 05 mm, 08 mm and 11 mm and the same insulation thickness of 015 mm A 20 mm long coil heater was used as the ignition source to generate a controlled heat flux Experiments show that increasing the current of wire leads to a convexly decreasing critical heat flux for ignition, agreeing with model predictions Effects of different currents on insulation temperature and flame height are discussed The flame width of three types of wires could be considered invariable with the current, which are 906 mm, 1245 mm and 1507 mm respectively The heat release rate of flame is discussed through the volume of flame and a correlation is presented that ΔV F ∝ I 2 The likelihood for molten PE dripping is determined by the absolute and relative fuel load for different wires Finally, the correlation between the flame propagation velocity and the current of wire, Δv f ∝ I 2, is demonstrated

20 citations


Cites background from "Risk-based spacecraft fire safety e..."

  • ...[18] loaded three levels of power (100 W, 600 W, 1200 W) to wires to study the smoke particles of the insulation....

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Journal ArticleDOI
TL;DR: In this article, the air flow rate in the cup-burner model was varied between 10 −L/min and 40 −L /min for a low-speed numerical model and was validated against the BS ISO 14520 cup burner test to determine the extinguishing concentration of nitrogen.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the authors performed ground-based, microgravity experiments attained by aircraft parabolic flight and drop tower on flame spread phenomenon over electric wire, which can provide relatively long microgravity period, and confirmed that the apparatus can work properly in microgravity.
Abstract: Ground-based, microgravity experiments attained by aircraft parabolic flight and drop tower on flame spread phenomenon over electric wire are performed. These are the preliminary tests for expected long-term microgravity experiments by sub-orbital or on orbit microgravity experiment. The main objectives of this study are (1) to confirm the apparatus can be work properly in microgravity and (2) to show the necessity of long-term microgravity experiments in order to observe the unsteady phenomenon. The flame spread rate and the total soot volume are important items as fundamental characteristics of the spreading flame. From the parabolic flight test, which can provide relatively long microgravity period, it is confirmed that the apparatus can work properly in microgravity. On the other hand, the quality of microgravity provided by aircraft is fair including G-jitters, and dependable data in the slow external flow velocity regime is hardly expected. Flame spread rate and the total soot volume are measured by drop tower, which can provide 10-4G microgravity environment. Although, in some conditions, the flame spread phenomenon seems to reach steady-state within the available microgravity time with the drop tower (∼ five seconds), the phenomenon includes periodical change in flame shape in reality. Consequently, to confirm the actual steadiness of the spread phenomenon, at least 10-4G microgravity environment and long-term microgravity environment is necessary.

9 citations

References
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Journal ArticleDOI
07 Dec 1990-Science
TL;DR: The subjectivistic (Bayesian) theory of probability is the appropriate framework within which expert opinions, which are essential to the quantification process, can be combined with experimental results and statistical observations to produce quantitative measures of the risks from these systems.
Abstract: Safety assessments of technological systems, such as nuclear power plants, chemical process facilities, and hazardous waste repositories, require the investigation of the occurrence and consequences of rare events. The subjectivistic (Bayesian) theory of probability is the appropriate framework within which expert opinions, which are essential to the quantification process, can be combined with experimental results and statistical observations to produce quantitative measures of the risks from these systems. A distinction is made between uncertainties in physical models and state-of-knowledge uncertainties about the parameters and assumptions of these models. The proper role of past and future relative frequencies and several issues associated with elicitation and use of expert opinions are discussed.

566 citations

Journal ArticleDOI
TL;DR: An understanding of the behavior of the fire plume and fire-induced flow near the ceiling of a room is necessary if one is to optimize detector response time and placement as discussed by the authors, which is the case in this paper.
Abstract: An understanding of the behavior of the fire plume and fire-induced flow near the ceiling of a room is necessary if one is to optimize detector response time and placement.

366 citations

Journal ArticleDOI
TL;DR: In this paper, fuel-lean flammability limits and burning velocities in a closed vessel were measured for methane-air mixtures burning at earth gravity (oneg) and zero gravity (zero-g) at initial pressures of 50-1500 Torr.

124 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the laminar smoke point properties of non-buoyant flames, due to their relevance to many industrial processes where effects of buoyancy are small.

82 citations

Proceedings ArticleDOI
01 Jan 1989
TL;DR: An overview of reduced gravity re-search performed in NASA ground-based facilities sponsored by Microgravity Science and Applications Program of the NASA Office of Space Science and Application is presented in this article.
Abstract: An overview of reduced gravity reasearch performed in NASA ground-based facilities sponsored by Microgravity Science and Applications Program of the NASA Office of Space Science and Applications is presented. A brief description and summary of the operations and capabilities of each of these facilities along with an overview of the historical usage of them is included. The goals and program elements of the Microgravity Science and Applications programs are described and the specific programs that utilize the low gravity facilities are identified. Results from two particular investigations in combustion (flame spread over solid fuels) and fluid physics (gas-liquid flows at microgravity conditions) are presented.

42 citations