Procedia Engineering最新文献

Pool fires are the most common burning phenomena that are often reported to cause huge casualties and properties in process industry accidents. Therefore, it is important to deeply understand the combustion characteristic and thermal radiation of pool fires. This paper presents experimental study and theoretical analysis on the fire plume temperature in developing area and thermal radiation distribution of small-scale propane pool fires. The results show that fire plume temperature should be formulated by (z/Q^2/5) for z/Q^2/5 ranging from 0 to 0.02, in comparison with the constant temperature assumption in literature. The fire plume temperature reaches the maximum value as z/Q^2/5 equals 0.02. The Point Source Model and Shokri-Beyler Correlation can relatively accurately calculate the radiant heat flux, while Mudan-Croce Method gives a bad prediction on the thermal radiation in small pool fires.

The potential of risk communication as tool for reducing the devastating impacts posited by disaster hazards on human lives and property has been discussed extensively in literature. Most risk communication studies and strategies focus on awareness creation and education on disaster hazards. However, awareness creation and education on disaster hazards do not necessary translate into preparatory attitude and behaviour towards disaster hazards. Frantic efforts are required to persuade and motivate people at risk to convert hazard awareness and education into preparation towards disaster hazards. Against this backdrop, this paper develops a conceptual model through literature review to facilitate and enhance disaster preparedness through risk communication.

Much research has been conducted to increase the resilience of healthcare service to major hazards; however, every time a major hazard takes place we discover that this critical service is yet to reach the anticipated resilient state. This paper reports an ongoing research work that looked at: the resilience of the structure of healthcare facilities, equipment stability, lifeline (utility) supplies, the interaction between hospitals and emergency agencies and the support the latter can provide during major emergencies. This paper presents findings on the ability of human resources to deal with the stress associated with major hazards. A mixed research method was adopted, including a systematic literature review followed by a survey to gather evidence about the stress level amongst healthcare staff in hospitals and their motivation. The literature review was conducted to find information about the level of stress healthcare staff experience with during major emergencies. Findings suggest that healthcare staff remain at high risk of stress and thus represent a major weakness of healthcare service resilience. The research concludes with a set of recommendations to address this issue.

This works aims at identifying the influence of surface integrity parameters on fatigue life of a 15-5PH. The effect of residual stress profile, surface roughness and microstructure are investigated. Various cutting and superfinishing processes (turning, ball burnishing and belt finishing) are used so as to reach various engineered surface integrities and as a consequence to highlight the influence of each surface integrity parameter. Rotary-bending tests have been carried out on samples to determine the average fatigue strength at 2 million cycles. It is shown that the influence of a deep compressive sublayer is by far more important than the ones of surface roughness or microstructure. The so-called ‘white-layer’ brings also a slight improvement of fatigue resistance.

Mechanical response of CFRP unidirectional prepreg was investigated under tensile quasi-static and fatigue loading. Firstly, the findings of an initial investigation on the effects of the end tabs and gripping condition are presented. A dialogue between numerical simulations and experimental tests led to avoid premature splitting failures in the clamps. Proper tensile failure is assessed in the gage length, at enhanced strength levels for the material considered. Consequently, the unidirectional material was successfully tested under tension-tension fatigue, at high load levels. Fatigue damage mechanisms arise at high stress amplitude, revealing that also a UD laminate can suffer from fatigue degradation along the fibres direction.

Most structures are fabricated using welded joints because of its low cost, structural strength and geometric flexibility. Welding is considered a highly complex metallurgical process that results in irregular geometries, material imperfections/flaws and tensile residual stresses. High tensile residual stresses and stress concentrations resulting from the weld process have a significant impact on fatigue life of structures, and thus a topic of great concern in product design. Ultrasonic impact treatment (UIT) is regarded as one of the most effective post welding treatment techniques to enhance the fatigue performance of welded structures. The UIT aims to introduce fatigue-beneficial compressive stresses by plastically deforming the weld toe and reduce stress concentrations by modifying local weld geometries. In this study, 3D modeling and simulation using finite element (FE) method has been performed to simulate welding process and numerical modeling of the UIT process to predict weld residual stress distribution of butt and T weld joints. The predicted numerical results under as-welded and UIT treatment conditions were compared to present weld residual stress improvements. Compared results shows that the UIT has potential applications on the fatigue design of welded structures, can lead to lighter structures and products, in which structures can be down-sized and optimized to reduce weights.

After Montreal protocol, more and more new materials have been applied as the substitutes of Halon. Much attention has been paid to fire extinguishing efficiency of alkali metal salts and ammonium phosphate salts, but the effects of particle sizes have not been studied sufficiently. The fire-extinguishing efficiency of a new kind of agent based on magnesium hydroxide of different particle size was studied in this paper. Four different size powders have been used to study their fire-suppression efficiency through laboratory scale experiments in a confine space of 1*1*1m. The physical and chemical characteristics of the magnesium hydroxide powders were characterized by scanning electron microscopy (SEM) and thermal gravity analysis (TGA). The results have exhibited that these four kinds of powders are all high efficient for the fire suppression efficiency and there is a threshold value of 5μm for the fire suppression efficiency of magnesium hydroxide. The efficiency can be affected by the morphology of powders and particle size. The powders of larger specific surface area and smaller particle size are more efficient to suppress fire. Fire extinguishing and possible fire-suppression mechanisms have also been analyzed from three aspects: chemical inhibition, cooling effect and asphyxiation effect.