A Numerical Study on the Damage Assessment of a Simply-supported Beam on Natural Frequencies

Based on the perturbation theory, it was proved that the ratio of changes of frequencies is the function of structural damage location. Taking a uniform cross-sectioned simply supported beam for example, the ratio of changes of frequencies between the damaged and intact beam was used to locate and qualify beam damage. For different extents of damage, the changes of frequencies and ratio of changes of frequencies were studied and the effects resulted from the omission of second order items were discussed. Finally, the deficiency of this method was pointed out.     

Analysis of Differential Shrinkage Deflection for PC Box girder Bridges

The long term deflection behavior of long span continuous rigid frame bridges has often attracted the attentions in engineering field. Based on the moisture diffusion theory, the calculation method of differential shrinkage deflection was proposed for PC box girder bridges. Finite Element Method(FEM) model of 2 D moisture field were established for typical cross sections of a case bridge. And the distribution law and the time variation characteristics of moisture field were analyzed. Through the deformation coupling condition of moisture field, the drying shrinkage deflection of the bridge was calculated and analyzed. It was found that the differential shrinkage deformation was significant and great error would be with the conventional method. When considering the effect of differential shrinkage, the deflection in mid span was 3.1cm larger than that of the conventional method. Thus, the differential shrinkage was the main reason for long term deflection of long span continuous rigid frame bridges.     

基于AHP与Fuzzy在供应商绩效评估中的应用

对供应商的绩效进行评估,是建立一个有效供应链至关重要的环节,它不仅有利于选择合适的供应商,同时也起到了让供应商企业自身发现问题,并不断提高的作用。在实际问题中,对供应商的绩效进行评估时,数据经常具有模糊性,并且很多因素权重难以度量,使得整个评估工作变得主观化,导致评估结果不理想,不能真正反应供应商的绩效水平。采用层次分析法与模糊理论对影响供应商绩效的因素进行分析,得出了一种有效的对供应商绩效进行评估的方案。     

The Fuzzy Comprehensive Evaluation of the Risk of Technology Innovation for Enterprises

The author establishes a risk evaluation index system of technology innovation according to the character of technology innovation . In this index system, technology risk, the capability of coporate risk, market risk are taken into consideration as well as the situition of the interior and the exterior of coporate besides the difficulty of the technology. The index-weighted is calculated with AHP and the whole process of fuzzy comprehensive evaluation is developed , which gives the accurate evaluation for the echnology innovation risk and can be guided by an enterprise for control the risk. At last, an example is given.     

衢州市早稻低温冷害风险评估及大气环流背景分析

应用衢州市1960—2012 年日气象观测资料,针对早稻苗期出现低温冷害灾害,从气象因子入手,建立定量评估模型,分析较严重的早稻春季低温冷害年大气环流背景,为提高春季低温冷害预报和预警水平,应对春季低温冷害对早稻构成的严重威胁。采用主分量分析法确定主分量及表达式,建立综合评价指标模型,计算出综合评价指标,并且对历年综合指标进行了评价。应用NCEP 1°×1° 500 hPa、850 hPa 资料,分析了较严重春季低温冷害年的大气环流背景。结果表明：从1960—1997 年春季低温冷害发生频率3~4 年出现一次,强度为1987—1997 年最强,2000 年以后,春季低温发生次数甚少。1987年、1993 年、1996 年、2010 年出现了较严重的早稻春季低温冷害,相对应的气候异常。综合评价指标和早稻产量相关密切,能客观地反映低温冷害的风险程度。较严重的早稻春季低温冷害年4 月上中旬亚欧地区呈径向型环流,使冷空气活动频繁南下,导致长江中下游地区气温偏低,而副热带高压强度强,南支槽、西南暖湿气流活跃,造成长江中下游地区持续阴雨天气。西风带、副热带、热带系统的有利配置,是造成早稻春季低温冷害发生的大气环流背景。