Chloride Transport in Splitting Cracked Concrete at Marine Tidal Zone

The chloride ion transport in concretes with different size of splitting cracks at marine tidal zone is investigated. The splitting crack widths of concrete are about 003 mm, 005 mm, 010 mm, 015 mm and 030 mm. The cracked concrete and sound concrete are placed at marine tidal zone for 30 d, and the chloride ion content in crack zone and perimeter zone of concrete, chloride ion penetration depth and steel bar corrosion area are quantitatively determined. It is shown that splitting crack will be recovered when the concrete is unloaded in split test. And the splitting crack width of concrete should be characterized by the value of displacement sensor when the concrete is unloaded in split test. The chloride ion content of cracked concrete decreases with increased depth, and then gets to remain steady from 10 mm to the inner. The relationship between chloride ion content and crack width in the steady zone can be regressed as the exponential function and the linear function for the crack zone and the perimeter zone of concrete, respectively. Due to away from the crack zone, the influence of splitting crack width on accelerated chloride ion ingression in the perimeter zone is less than that in the crack zone. When the splitting crack width is more than 005 mm, the chloride ion penetration depth in crack plane and in vertical crack plane of concrete is 50 mm and 20 mm, respectively. And the steel corrosion area enlarges with the increasing crack width. And the chloride diffusion coefficient of cracked concrete is closely related to the resistance capacity to chloride penetration of concrete, crack density (matrix width, crack width), and chloride binding capacity of concrete. When the crack density of concrete is less than 70, the chloride diffusion coefficient of cracked concrete increases with decreased crack density linearly. The chloride penetration will accelerate near the crack zone. And the raised splitting crack width will lead to its influence area in concrete increased quickly.     

Microcracking and Chloride Penetration of Concrete under Uniaxial Compression

A non-destructive method of evaluation of specific crack area was used to characterise microcracking in concrete prisms during uniaxial compression loading and unloading. Chloride profiles were also measured after the same concretes were exposed to chloride environment. The relation among microcracking, stress-strength ratio and chloride penetration of concrete were analysed based on the experimental results. Under compressive load, the apparent chloride diffusion coefficient decreases until about one third of the ultimate load. Further increase of compressive load improves the chloride diffusion coefficient again. There is a close link between microcracking and stress-strength ratio. The index of specific crack area can be used to indicate the microcracking and study chloride transport behaviour into concrete under the influence of microcracking.     

基于环路和改进遗传算法的树状灌溉管网优化

以投资最小为目标函数,建立了树状灌溉管网优化数学模型,用外部惩罚函数法将问题转化为无约束优化问题,并采用改进遗传算法进行求解。根据树状管网优化的特点,遗传算法采用二进制编码和整数编码相结合的双重编码,以同时对管网布置形式和管径进行优化。在遗传算法产生初始解及交叉、变异操作时,采用基于环路的方法,减少了不可行解的产生,提高了算法的计算效率,算例说明该优化方法有效、实用。     

复杂注水系统泵站优化调度的改进遗传算法

以耗电量最小为目标函数,排量、压力等限制为约束条件,建立了复杂注水系统泵站优化调度数学模型.针对系统运行特点,采用改进遗传算法对模型进行求解,同时优化出泵的运行状态和排量.改进遗传算法采用实数编码,并设计了随机多父辈交叉方法,改进了变异操作,操作过程中,给出了泵排量的处理方法,使各水量约束条件得到满足,大大减少了不可行解的产生,使算法的优化性能得到了提高.算例说明了该优化方法的有效性.     

基于有限元方法的载货汽车驱动桥壳分析

对载货汽车驱动桥壳进行了强度计算和有限元模拟分析,得出了零件的应力和变形分布,验证了设计的合理性,为汽车驱动桥的强度评价及疲劳寿命估算提供了相关数据。     

考虑配置的多源注水系统泵站运行方案优化

为了实现对多源注水系统中各站内运行注水泵的型号、数量及运行参数同时进行优化,以系统输入功率最小为优化目标,考虑水量平衡、泵流量、泵正常运行压力、泵型号等约束,建立了考虑泵配置的泵站运行方案优化数学模型.针对优化问题的特点,设计了双重编码改进遗传算法对模型进行求解.在双重编码中,第1行采用实数编码表示泵的流量,第2行采用整数编码表示泵所属注水站编号,实现了对优化变量的准确描述,并指出了解的编码为变长度编码.设计了根据流量确定泵型号的方法,泵的其他运行参数根据选择的泵型号确定.在改进遗传算法操作过程中,设计了初始解的产生方法及与问题相适应的多种交叉和变异方法,使部分约束条件得到了满足,减少了不可行解的数量.利用本算法对某深度注水系统进行了优化设计,优化后系统输入功率比现状降低了2.42%,表明在多源注水系统中对泵的配置及运行参数进行同时优化节能效果明显.     

PS/2标准键盘与单片机的连接

分析了PS/2标准键盘的通信协议,阐述了其编码的扫描原理,提出了51单片机与PS/2键盘的接口设计,并通过LCD1602显示了键盘的输入情况。     

一类带阻尼项的二阶强迫非线性微分方程的振动性判定准则

本文建立了二阶强迫非线性微分方程(r(t)ψ(t))|y′(t)|~(a-1)y′(t))′ P(t)ψ(y(t))|y′(t)|~(a-1)y′(t) q(t)f(y(t))=e(t),α＞1的振动性判定准则,其中t≥t_0．这些振动性非决定准则仅依赖于[t_0,∞)的子区间序列的性质。所得结果比Cak- mak and Tiryaki[1]及Li and Cheng[2]中结果适用更广泛。     

渤海石油平台污损生物生态研究

2013年9月-2014年9月在渤海海域进行了污损生物挂板试验,共记录污损生物24种,以温带种和广温种为主,优势种是多棘麦秆虫(Caprella acanthogaster)、日本大螯蜚(Grandidierellajaponica)、理石叶钩虾(Jassa marmorata)、拟钩虾(Gammaropsis sp.)等.季板分析结果显示,表层季板的平均生物量为1764.23 g/m2,中层季板的平均生物量为2322.31 g/m2.试验海域全年均有污损生物附着,但种类和附着量季节性差异明显,污损生物附着盛期为夏季和秋季.污损生物群落Shannon-Wiener多样性指数(H')和Margalef丰富度指数(d)秋季最高.多元统计分析表明,污损生物群落按时间可分为3个群落类型,反映出渤海海域污损生物群落的季节变化明显.相关性分析显示,表层和中层试板污损生物的生物量与水温具有显著的相关性,相关系数分别为0.959和0.986(P＜0.01).     

季节性河道渗漏野外试验研究

为研究季节性河流大沽河河道的渗漏规律,以包气带水分运动理论为基础,在大沽河上、中游建立有代表性的试验场,进行野外现场入渗试验,研究不同包气带岩性下河道的入渗能力.结果表明:干涸河道入渗过程可分为非稳定入渗和稳定入渗两个阶段;包气带的水理性质影响着河床的入渗规律,大沽河河道上游的入渗率比中游的入渗率大,上游和中游南沙梁村...