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T. Paulos

Bio: T. Paulos is an academic researcher from University of California, Los Angeles. The author has contributed to research in topics: Fire prevention & Risk assessment. The author has an hindex of 2, co-authored 4 publications receiving 25 citations.

Papers
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Journal ArticleDOI
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.

16 citations

01 Jul 1992
TL;DR: The importance of understanding and testing smoldering as a likely fire scenario in space and the need for smoke damage modeling, since many fire-risk models ignore this mechanism and consider only heat damage are discussed in this paper.
Abstract: Discussions from a workshop to guide UCLA and NASA investigators on the state of knowledge and perceived needs in spacecraft fire safety and its risk management are reviewed, for an introduction to an analytical and experimental project in this field. The report summarizes the workshop discussions and includes the visual aids used in the presentations. Probabilistic Safety Assessment (PSA) methods, which are currently not used, would be of great value to the designs and operation of future human-crew spacecraft. Key points in the discussions were the importance of understanding and testing smoldering as a likely fire scenario in space and the need for smoke damage modeling, since many fire-risk models ignore this mechanism and consider only heat damage.

8 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the differences between a fire on-board a spacecraft and one in a terrestrial facility that must be accounted for in any risk assessment, and discuss some of the methodology modifications, as well as several experimental results.
Abstract: Due to the closed environment of a spacecraft and the lack of egress, fire on-board may pose a significant risk. There are many differences between a fire on-board the spacecraft and one in a terrestrial facility that must be accounted for in any risk assessment. Both the risk assessment methodology and the phenomena-based models for terrestrial applications must be modified. This paper discusses some of the methodology modifications, as well as several experimental results. Multiple experiments have been conducted in terrestrial and microgravity environments in order to construct and validate models required for the assessment and management of risk on-board spacecraft. Past Shuttle experience with electrical overheating events supports the belief that these types of events may pose a serious threat to any human-crewed spacecraft andlor the crew. Experiments have been performed to simulate these events and quantify several damage modes. A preliminary set of experiments at the 2.2 second NASA Lewis Drop Tower has led to several conclusions. First, the production of damage causing elements depends on temperature. Second, the wire insulation involved can have a significant impact on the risk of the event. Third, the smoke particle size distribution is shifted towards larger sizes in microgravity, which may prove important in designing a smoke detector or selecting a sensitivity.

1 citations


Cited by
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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

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

Proceedings ArticleDOI
10 Jan 2005
TL;DR: In this paper, the authors present a research plan for fire detection in future extraterrestrial vehicles and habitats on long-range, long-duration missions, where the first line of defense lies in determining the ignitability and flammability of candidate materials under reduced and microgravity conditions and at appropriate oxygen mole fractions.
Abstract: Fire is a particularly critical danger in future extraterrestrial vehicles and habitats on long-range, long-duration missions since, unlike in most scenarios here on Earth, escape is not an option and the fire department will not be coming. In such vehicles and habitats, the first line of defense lies in determining the ignitability and flammability of candidate materials under reduced and microgravity conditions and at appropriate oxygen mole fractions and then using this information to help select materials to be used in these vehicles and habitats. If, despite our efforts to prevent a fire, one does occur, our next line of protection is fast and reliable detection of such occurrences (with minimum false positives) and definition of their locations. After a fire and its location have been identified, we must have reliable means of extinguishing this fire as quickly as possible with as little impact to the mission and crew as possible. Finally, post-fire cleanup, toxicology of fire products and products of the interaction of the flame with the extinguishant, and virtual simulation training of the crew in fighting fires are also important areas which must be addressed by the research plan presented in this paper.

25 citations

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

Journal ArticleDOI
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.

16 citations