Sensitivity and uncertainty analyses for ignition of fiber‐reinforced polymer panels

The ignition characteristics of combustible solids are affected by many factors such as material properties, external heating source, and surrounding environmental conditions. In practice, these factors can vary significantly from one application to another. Thus, it is important to evaluate the sensitivity and uncertainty aspects of the effect of these factors on ignition. This study attempts to achieve this goal through sensitivity and uncertainty analyses on the piloted ignition of fiber‐reinforced polymer (FRP) composite panels. A Monte Carlo simulation using the Latin hypercube sampling method was employed to conduct sensitivity and uncertainty analyses. An integral model combining a general thermal thickness model with a heating rate‐related ignition temperature criterion was used as the ignition prediction model. Time‐to‐ignition was evaluated as the output parameter against the variations of input parameters such as material properties, external heating source, and surrounding environmental conditions. In addition, to identifying important sensitivity factors and uncertainty ranges of piloted ignition, a critical thermal thickness was found for the composite panels. These findings can serve as guides for the fire safety design of FRP composite materials for various applications. Copyright © 2015 John Wiley & Sons, Ltd.     

A Cumulative Perceived Value-Based Dynamic User Equilibrium Model Considering the Travelers’ Risk Evaluation on Arrival Time

This paper presents a cumulative perceived value-based dynamic user equilibrium model by applying the prospect theory to formulate the travelers?? risk evaluation on arrival time. The network uncertainty caused by link exit capacity degradation is incorporated into the analysis. The model which considers departure time and route choices simultaneously is expressed by a variational inequality in a discrete time space. Numerical results show that the travelers?? risk preference indeed has big influence on flow distribution. Our study constitutes a deepening of cognition in developing more realistic dynamic traffic assignment technologies.     

硅钢退火炉氮气冷却的碳套辊分析

阐述了传统硅钢退火炉无冷却碳套辊的缺点,并介绍和分析了通氮气冷却碳套辊的技术特点。     

衍射光栅槽形隆起的数学建模及演变规律

以79g/mm的中阶梯衍射光栅为目标,研究衍射光栅机械刻划过程中铝膜的槽形隆起机制。首先,经过4次坐标变换,建立了光栅槽形的塑流剖面。然后,基于Lee and Shaffer提出的滑移线场模型,在塑流剖面内建立起包含滞留区域的滑移现场模型,并根据Dewhurst and Collins提出的矩阵算法对滑移线场进行求解,最终得到槽形隆起尺寸模型。最后,通过DEFORM软件对槽形隆起尺寸的演变规律进行模拟分析。     

China’s Oil & Gas Imports and Exports in 2013

Demand for imported oil is weakened by economic growth decline, In 2013＇ growth of China＇ s oil imports dropped to the lowest in 8 years, but net imports topped 300 million tons. Domestic oil demand will continue to grow slightly in 2014, and development of alternative fuels will restrict growth of oil import.     

Structure of Cu-Sn Melt at High Temperature

The temperature-dependent viscosity and X-ray diffraction (XRD) patterns of a Cu₆₅Sn₃₅ melt were investigated at high temperatures. The viscosity of the melt changed discontinuously at about 1283?K (1010?°C). An XRD analysis of the Cu₆₅Sn₃₅ melt revealed no obvious changes in the correlation radius, whereas the coordination number increased abruptly at a similar temperature with that mentioned previously, i.e., 1283?K (1010?°C) during the cooling process. The results indicate a redistribution of atoms in the nearest environment. The structural transition at the higher temperature was attributed to a change of combination mode of nearest atoms in the short-range order cluster of the Cu₆₅Sn₃₅ melt.     

图解法砼施工技术交底的应用--惠州百利通广场项目案例分析

工程主体施工中，砼浇注分项工程施工具有劳动量大、时间持续长、质量要求高等特点，且涉及人、机、料、法、环五大要素。为做好计划、调配、组织、协调工作，落实施工方案，实现预定的工期、质量、安全目标，做好技术交底显得尤为重要。