查48区块葡萄花储层四性关系研究

查48区块葡萄花油层经历了复杂的沉积和成岩作用,具备低孔低渗特点。利用测井、录井、岩心和试油等资料,分析了该区储层的岩性、物性、含油性和电性特征及其相互关系,并确定出了该区有效厚度下限标准:孔隙度为10.2%,渗透率为0.14 mD;电性下限电阻率为5.5Ω·m,声波时差为250μs/m,含水饱和度小于63%。从而为查48区块进一步储层评价和增产,提供了有力的依据。     

充液锚固罐振动特性分析

储液容器自身振动特性的研究,一直是研究的热点。从储液深度,罐壁变厚度因素出发,考虑储液高度的不同,罐壁厚度的改变对系统频率的影响。结果表明:充液高度的提升,系统自振频率呈现下降趋势,储液罐含不同高度液体,其结构的振动形式和含液量无必然关系。罐壁变厚度对系统的频率值影响很小,采用等厚度罐壁代替变厚度罐壁理论上是可行的。     

AGC在京唐1580生产线的应用及改进

分析了轧制过程中轧辊偏心产生的原因以及对带钢厚度的影响,增加了轧辊偏心补偿的方法,然后推导了主要结果并分析了其机理,并应用于京唐1580生产线实际的带钢厚度自动控制系统(AGC),通过实践,此种形式控制方式具有较好的精确性。     

Q345/316L异种钢焊接残余应力与变形数值模拟

文中基于SYSWELD有限元分析软件对Q345/316L异种钢焊接过程的瞬态温度分布、残余应力及变形进行了数值模拟,并通过试验对其模拟结果进行了验证. 试验测量结果与数值模拟结果吻合良好,证明了利用SYSWELD模拟异种钢焊接的可靠性. 结果表明,异种钢焊接温度场呈不对称分布,Q345侧的高温区域范围更大. 不论是横向残余应力还是纵向残余应力,沿焊缝方向均呈帽状分布且在焊缝中部位置存在最大残余应力;在垂直于焊缝中央截面上,纵向残余应力与横向残余应力在焊缝和焊缝附近区域分布是不连续的,存在较大的应力梯度且应力状态也较复杂,而最大残余应力出现在Q345侧的熔合线处. 不同的热输入下模拟结果表明,在保证焊接接头质量的前提下,最好采用小热输入的焊接工艺.     

基于空气中冲击波信号能量的激光冲击强化在线检测方法

目的 为克服激光冲击强化现有离线检测方法的缺点,提出了一种基于空气中冲击波信号能量的激光冲击强化在线检测方法。方法 利用波长为1064 nm、脉宽为14 ns、单脉冲能量为5~7 J的Nd:YAG激光器对经过振动时效处理的TC16钛合金试件进行激光冲击强化处理。用自主研制的信号放大器对空气中的冲击波信号进行一级放大后,再经前置放大器、数据采集卡传输到计算机控制系统,从而实现对空气中冲击波信号的采样、存储、滤波和数据分析,并从中提取冲击波信号能量。用X-350A型X射线应力测定仪测量TC16钛合金试件经激光冲击强化处理后的表面残余应力。最后对所得实验数据进行多项式拟合,以获得材料表面残余压应力与冲击波信号能量之间的经验公式。结果 经激光冲击强化处理后,材料表面形成了一定大小的残余压应力。随着激光能量的增加,材料表面残余压应力及冲击波信号能量均增加,且二者的增加趋势一致。结论 在激光冲击强化过程中,对空气中传播的冲击波信号进行采集和提取其信号能量,可以预测试件经激光冲击强化处理后的残余应力,能够准确判断激光冲击强化质量,从而实现工业过程的在线检测。     

Migration and occupational careers: The static and dynamic urban wage premium by education and city size

Using matched employer-employee full population data on regional migrants in Sweden, this paper addresses the question whether the urban wage premium, and ‘thick’ labour market matching effects, are to be found across all educational groups, and whether the population threshold for these types of effects varies by educational category. Estimating initial wages, average wage level and wage growth 2001-2009, we find similar wage premiums for all workers in the three largest metropolitan areas, but that there are distinct population thresholds for these type of effects, regardless of educational background. However, job search behaviour as explaining dynamic effects over time seems to pertain mostly to those with higher education.     

Optimum design for unbonded posttensioned precast split shear wall system using genetic algorithm

Precast concrete structures are increasingly being adopted by building designers in regions of high seismicity. An unbonded posttensioned (PT) precast split shear wall system (UPPSSW) was proposed by the Precast Seismic Structural Systems (PRESSS). The UPPSSW system is composed of two or more single precast concrete wall panels that are connected together with energy‐dissipating shear connectors and anchored to the foundation with unbonded PT tendons located at the panel center. In this paper, an optimum design program has been developed for designing this system. The objective of the optimum process is to find the optimum combination between PT tendons and shear connectors while keeping the moment capacity of the wall equal to the applied design moment and achieving zero residual drift simultaneously. In addition, MATLAB was employed to explore an optimization program using genetic algorithm. Compared with the existing design methods for the system, the optimum design program proposed in this research is accurate, efficient, and direct. Moreover, it can yield the optimum design automatically and quickly. As a result, the existing lengthy and manual design process of trial and error for the system can be avoided.     

Collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete frames using fibre reinforced plastics

Considering residual service life, this paper presents a collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete (RC) frames using fibre reinforced plastics (FRP). With the assumed uniform corrosion model, corrosion-induced initial damage combined with subsequent earthquake-induced damage is identified by the multi-mode-based global damage model developed previously. The collapse-level earthquake intensity determined by incremental dynamic analyses (IDA) with the damage model and the maximum considered earthquake (MCE)-level intensity considering residual service life are combined to generate the time-variant collapse safety margin assessment of corroded RC structures. Based on this assessment, the collapse safety margin-oriented FRP seismic retrofit strategy is proposed and demonstrated on a 4-storey frame. The damage model originally developed for earthquake scenarios has also exhibited its rationality for characterising corrosion-induced initial damage and its influence on coupled damage development with subsequent earthquake excitation. Seismic retrofitting with FRP composites should consider the effects of the corrosion development stage, target collapse safety margin and residual service life. FRP retrofits can cause decreases in the MCE-level collapse probability and increases in the collapse resistance of corroded RC structures. Retrofitting carried out at different times achieves different efficiencies and different time-variant collapse safety margins within the residual service life.     

基于PSO-GRNN模型的埋地管道腐蚀剩余寿命预测

目的 构建埋地管道腐蚀深度预测模型,预测腐蚀管道的剩余使用寿命。方法 依据ASME B31G剩余强度评价标准,给出管道的最大允许腐蚀深度计算方法,引入广义回归神经网络（GRNN）,构建埋地管道腐蚀深度预测模型,采用粒子群算法（PSO）优化GRNN的网络参数,结合管道腐蚀发展趋势预测方法,对埋地薄弱管道进行腐蚀剩余寿命预测。以陕西省某埋地输油管道为例,选取8个主要外腐蚀因素,构建外腐蚀指标体系,借助Pycharm编程仿真,结合埋片试验,对该模型预测结果进行验证分析,并预测各腐蚀管段剩余使用寿命。结果 与BP模型相比,PSO-GRNN模型的管道腐蚀深度预测结果最大相对误差控制在13.77%以内,平均相对误差仅为6.63%。寿命预测结果显示,部分管段的剩余使用寿命未能达到其预期服役寿命。结论 所建模型预测性能要明显优于BP模型,预测精度更高,能够较好地预测埋地管道的最大腐蚀深度和未来的腐蚀发展规律,剩余寿命预测结果贴近实际,为管道的维修和更换提供了指导依据,在实际工程中,具有一定的应用价值。     

工艺参数对钴基合金等离子熔覆残余应力的影响

目的 探究钴基合金等离子熔覆在不同工艺参数下残余应力的分布规律,选取最优工艺参数组合,以达到降低残余应力的目的。方法 设计正交试验,采用等离子熔覆技术制备9组不同工艺参数下单道钴基等离子熔覆样件,利用盲孔法对每个样件的熔覆起点、中间位置及终点位置的残余应力进行测量,分析工作电流、扫描速度、送粉速度等工艺参数对残余应力的影响规律。结果 工件表面残余应力主要以拉应力为主,其中间位置的残余应力最大。各个位置平行于扫描路径方向的残余应力均大于垂直于扫描路径方向的残余应力。当工作电流为92 A、扫描速度为100 mm/min、送粉速度为12 r/min时,所成形的样件残余应力最小。结论 工作电流对熔覆起点和终点平行于扫描路径方向的残余应力影响最为显著,其余各位置各方向上,影响最显著的因素为扫描速度。工作电流越大,残余应力越大;随着扫描速度的增大,残余应力不断变小;随着送粉速度的增大,残余应力有增大的趋势。选取合适的工艺参数组合能够有效地控制残余应力。