Weigang Yan

Bio: Weigang Yan is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Flame spread & Laminar flame speed. The author has an hindex of 9, co-authored 11 publications receiving 174 citations. Previous affiliations of Weigang Yan include University of Shanghai for Science and Technology.

Theoretical and experimental study of width effects on horizontal flame spread over extruded and expanded polystyrene foam surfaces

Abstract: In order to explore the mechanisms of horizontal flame spread over thermal insulation foam surfaces, extruded polystyrene and expanded polystyrene foams were selected to carry out a series of experiments with different sample widths ranging from 4 to 16 cm. Temperatures in both the solid phase and the gas phase were measured, with considerable differences being found between extruded polystyrene and expanded polystyrene in their temperature profiles. Extruded polystyrene also showed a distinct pyrolysis stage, while expanded polystyrene showed a lengthy melting stage differences that may be explained from their different thermal properties. The flame spread rates of both materials first decreased and then increased with increasing sample widths. The minimum flame spread rates were at widths of 8 and 10 cm for extruded polystyrene and expanded polystyrene, respectively, resulting from the relative differences between convection and radiation heat flux, which were different for the two foams. Numerical equa...

An evacuation model coupling with toxic effect for chemical industrial park

Abstract: Emergency evacuation plan plays a key role for disaster management and successful evacuation. In this work, a conceptual decision support system is established and a method to determine the evacuation scope under toxicant leakage accidents is also proposed. Simultaneously, a route selection approach coupling with polluted scope is proposed based on operation mathematic analysis. The best route for evacuee at each location on toxic leakage accidents is the one along with which the heath injury is minimal. Hence, a variable based on toxic load is defined and noted as D V i − V j , which is used to quantify the toxic exposure. The universally minimal D V i − V j is taken as the optimized goal in the model. And then, one case is presented and indicates that this approach can aid the emergency managers to make the right response to the leakage accident in an efficient manner. This new method is also useful for fire risk assessment and design of chemical industrial park.

Experimental study on the width and pressure effect on the horizontal flame spread of insulation material

Abstract: Organic insulation materials such as polyurethane foams are widely used as buildings' facade wall insulation materials in China. However, they are highly flammable and of great fire hazard by the chemical nature. In this paper, a series of laboratory scale experiments using rigid polyurethane foam were conducted and theoretical analysis was applied to evaluate the real fire performance of such materials under different situations. Temperature profiles in both solid and gas phases were obtained. This work provides basic correlations of flame spread characteristic of polyurethane foams regarding to width and pressure changes. Theoretical analysis on heat transfer of width and pressure effects was also provided. Good agreement of changing trends was found between experimental results and theoretical calculation.

Evacuation Processes of Different Genders in Different Visibility Conditions – An Experimental Study

Abstract: Practical data of human movement characteristics in different visibility conditions is necessary for the fire performance-based designs and evacuation calculation models. In this study, an evacuation experiment was conducted in a classroom and the evacuation processes were recorded by video cameras. The impacts of visibility and gender on walking speed were analyzed. The walking speed of young female pedestrians in good visibility conditions measured in our experiment is 0.92 m/s and in conditions without visibility the mean velocity is 0.42 m/s. Besides, the mean velocity of males in conditions with good visibility is 0.91 m/s and in zero visibility conditions the value is 0.69 m/s. Additionally, the distributions of velocities obtained in different visibility conditions in this study obey the Gaussian distribution. The results are similar to that of previous study. The research is helpful for devising evacuation schemes of theater, stadiums, gymnasiums etc. and also can be used in guiding regional evacuation processes, such as evacuation processes of chemical industrial parks whose building layouts and exit arrangements are similar to the classroom.

Experimental study of horizontal flame spread over rigid polyurethane foam on a plateau: effects of sample width and ambient pressure

Abstract: Summary The effects of sample width and ambient pressure on horizontal flame spread over horizontal rigid polyurethane foams are experimentally studied. A series of comparative experiments are conducted at two places with different altitudes in China. The sample surface temperature, spread rate, and height of flame are measured over a range of sample widths from 4 to 16 cm. Experimental results show that the horizontal flame spread rate decreases as the sample width increases in a negative power law at both two altitudes and the flame spread rate in the Hefei plain (at an altitude of 30 m) is larger than that on the Tibetan plateau (at an altitude of 3658 m) of the same width. The horizontal flame spread mechanism on the rigid polyurethane foam is analyzed qualitatively in comparison with the results of the flame spread rate of expanded polystyrene foams. The relationship between the dimensionless flame height (Hf/W) and the sample width (W) is obtained by using Froude number similarity. It is found based on the experimental data under two different ambient pressures that the average value of the exponent of the ambient pressure in the power law for the horizontal flame spread rate is about 1.9, which is in good agreement with the theoretical value 2.0. Copyright © 2014 John Wiley & Sons, Ltd.

The battery charging station location problem: Impact of users’ range anxiety and distance convenience

Abstract: Key to the mass adoption of electric vehicles (EV) is establishing a sufficient recharging infrastructure network, based on customer behavior and psychology. This study examines the battery charging station location problem, considering users’ range anxiety and distance deviations, two major barriers to the mass adoption of EV. The problem is formulated as a bi-level integer programming model based on a range anxiety function. Then, the problem is solved using an adaptive large-neighborhood search, combined with a k-shortest path algorithm and an iterative greedy heuristic. Finally, the effects of parameters are analyzed in the context of a real-world road network.

Mechanical, thermal and fire performance of an inorganic-organic insulation material composed of hollow glass microspheres and phenolic resin.

Abstract: Hypothesis Organic foamy materials possess good thermal insulation properties and inorganic materials are non-combustible. Hence, it is possible to develop a kind of organic-inorganic lightweight thermal insulation materials with excellent fire safety. Experiments Hollow glass microsphere (HGM), as one kind of lightweight noncombustible inorganic material, was chosen as the filling material. Phenolic resin (PR), as the flame retardant polymeric material, was used as binding material. A series of HGM/PR composites with various PR/HGM mass ratio were prepared. Properties, such as apparent density, microstructure, mechanical strength, thermal conductivity, burning behavior and flame retardancy of the specimens were determined, respectively. Findings The results show that the surface of HGM particles is coated by a layer of cured PR and the HGM powder is glued together firmly from the scanning electron microscope (SEM) images. With the increase of PR/HGM mass ratio, both of apparent density and mechanical strength of HGM/PR composites increase, but thermal conductivity and limiting oxygen index (LOI) values decrease, all of the specimens still possess high LOI value (>50%). What’s more, no flaming combustion (merely partial carbonization) and hardly any smoke can be observed during the burning process, which indicates the HGM/PR composites possess excellent flame retardant property and fire safety.

Sample width and thickness effects on upward flame spread over PMMA surface

Abstract: Upward flame spread has the same propagating direction with air flow and buoyancy, and features as the most hazardous fire case in all flame spread configurations. It has been a long time for fire researchers to find a simple and effective method to evaluate upward flame spread behaviors, especially for different materials and sample sizes. The aim of this work was motivated by the research of sample width and thickness effects on upward flame spread behavior, including flame spread rate during acceleration propagation for different sample thickness and width, theoretical global mass loss prediction based on Emmons's hypothesis, and dimensionless flame height scaling with dimensionless heat release rate for steady stage burning. Four kinds of sample thicknesses were selected, including 1.7, 3.5, 5, and 7mm. For each kind of thickness, six sample widths ranging from 40 to 90mm were prepared. To eliminate the side flame spreading effects, one set of contrast experiments with sample sides sealed was also performed, by which way flame could only spread along sample front surface and flame propagation was inhibited along both sides. Based on Emmons's hypothesis, a method for calculation of global mass loss rate was developed. Theoretical global mass loss rate over pyrolysis surface of upward flame spread configurations was calculated and could fit the experimental data well. Finally, a dimensionless heat-release rate for wall flames of different sample sizes was used to scale the dimensionless flame height with a power-law exponent 0.58. The results of this study have implications concerning designs for high-rise building fire safety problems and can help to get better understandings of upward flame spread mechanism from aspects of heat and mass transfer.

Quantitative Human Error Assessment during Abandon Ship Procedures in Maritime Transportation

Abstract: Human error prediction is always onerous work in the maritime domain since it is very difficult to obtain empirical data. One accepted method, Success Likelihood Index Method (SLIM), is utilized to assess human error as data is very scarce in the marine industry. The SLIM provides a quick tool to predict human error and evaluate human error probability (HEP) that occurs during the completion of a specific task. The weakness of the method is the subjectivity in the process of experts’ judgments causing difficulties in ensuring consistency. To remedy this gap, this paper proposes a fuzzy based SLIM technique which provides more accurate estimation during human error quantification. In the proposed approach, while the SLIM is utilized to estimate HEP, the fuzzy sets deal with the vagueness of expert judgments and expression in decision-making during the weighting process of performance shaping factors (PSF). To illustrate the proposed approach, the abandon ship procedure in marine transportation has been selected since the evacuation of the ship is critical to prevent the loss of life in the case of emergency. The outcomes of the paper can be utilized by ship owners, safety managers as well as ship management companies to minimize the likelihood of human error occurring within a specific task and to enhance overall levels of safety on-board a ship in the marine environment.

Optimal planning of swapping/charging station network with customer satisfaction

Abstract: Key to the mass adoption of electric vehicles is the establishment of a sufficient battery service infrastructure network on the basis of customer behavior and psychology. Motivated by EV service infrastructure network design under the battery leasing/electric car sharing service business models, we present an electric vehicle battery service network design problem considering a customers satisfaction related to “range anxiety” and “loss anxiety”. The problem is formulated as a linear integer programming model under deterministic and fuzzy scenarios. A Tabu Search heuristic combined with GRASP is proposed to efficiently solve the problem. Finally, we conduct parametric analysis on real-world road networks.