海底溢油输移扩散的可视化数值模拟系统

为直观研究溢油在复杂水下环境中的动态行为,设计和开发一套海底溢油可视化数值模拟系统(SIMPACT-SOS).系统由数值模型、数据库和图形界面构成,具有地理信息系统(GIS)应用平台、数值建模分析、溢油数值模拟等专业功能.应用算例表明,SIMPACT-SOS系统可为海底沉船溢油、海底输油管道泄漏、海洋石油钻井井喷等水下污染事故的风险评估、应急决策及损害评估提供理论和技术支持.     

氯盐腐蚀环境下混凝土结构时变可靠度计算

基于Fick扩散定律,建立了氯离子在混凝土中扩散的多因素修正模型,给出了模型中参数的取值。依据可靠性理论,考虑氯离子侵蚀深度的不同分布特征,利用建立的扩散模型,说明了氯盐侵蚀环境下考虑时变效应的混凝土结构可靠度计算方法。最后给出了实际工程算例,算例结果说明,假定氯离子侵蚀深度服从正态分布带来的计算偏差并不大,却可大大简化计算过程。     

Lagrangian modelling of plankton motion: From deceptively simple random walks to Fokker–Planck and back again

The movement of plankton, either by turbulent mixing or their own inherent motility, can be simulated in a Lagrangian framework as a random walk. Validation of random walk simulations is essential. There is a continuum of mathematically valid stochastic integration schemes upon which random walk simulations depend, each of which lead to radically different macro-scale dynamics as expressed in their corresponding Fokker–Planck equations. In addition, diffusivity is not a unique parameter describing a random walk and its corresponding Fokker–Planck equation. Spatially varying translation speed and turn frequency have different effects on population distributions. Validation requires extra information either in the form of the well-mixed condition for physical diffusion, or in detailed information on the sensing ability, internal state modulation and swimming response for plankton motility.     

横向稳定杆与汽车稳态转向特性关系的仿真研究

在充分考虑侧倾对汽车操纵稳定性影响的情况下,建立起基于横向动力学的整车模型,并进行了汽车稳态转向特性的仿真研究。     

Real-time assessment and prediction on maritime risk state on the Arctic Route

ABSTRACT

Recently, the Arctic Route has become busier with the continuous melting of Arctic ice. However, navigation on the Arctic Route would be much more complex than in normal water as harsh environmental conditions, such as ice-covered water and scarce costal ports that may cause more uncertainty. Nowadays, with the rapid development of sensors on board, more related data has become available. Thus, implementing comprehensive Arctic maritime risk assessment is urgent and necessary in practice. This study proposes an Arctic maritime risk state assessment method including real-time risk state assessment and risk prediction. Specifically, real-time observation samples’ numerical risk state would be firstly obtained with projection pursuit method from 10 risk indicators. Due to the fuzzy uncertainty of single observation set, information diffusion would be applied to provide diffusion estimation on risk probability distribution in order to depict risk state precisely. Also, the accumulated distribution can be regarded as the risk prediction for next time slot and risk entropy is introduced to depict risk tendency directly. Case study based on ‘Yongsheng’ is conducted to demonstrate and verify the effectiveness of the proposed method. The findings can be useful for the operators and management on board during the Arctic voyage.     

沥青再生剂扩散机理与扩散模拟试验研究

从扩散理论入手,分析再生剂与旧沥青之间的扩散机理．认为温度、再生剂性质和沥青性质是影响沥青热再生中再生剂扩散能力的3个重要因素。通过旧沥青向新集料的扩散模拟试验,分析了拌和时间、施工温度、再生剂量、旧沥青量对旧料扩散转移的影响。     

基于海洋暴露试验的氯离子扩散系数时空模型研究

在我国腐蚀条件最为恶劣的海南八所港,对3种配合比的混凝土试件进行实海暴露试验,通过测定浪溅区条件下氯离子在混凝土中侵入量,研究氯离子有效扩散系数随时间和深度的演变,为准确预测混凝土结构的使用寿命提供参考。     

不同环境条件下考虑荷载影响的氯离子扩散模型

钢筋锈蚀是造成钢筋混凝土构件耐久性破坏的重要因素之一,氯离子侵蚀是海洋环境下钢筋锈蚀的首要因素。根据相关文献给出的不同海洋环境、不同荷载水平作用下混凝土中氯离子扩散的实验数据,通过拟合给出氯离子扩散荷载影响系数与构件应力状态之间的关系式及混凝土表面氯离子浓度随时间变化的统计公式,建立了考虑荷载影响的氯离子扩散模型。多组现场实测数据检验表明,建立的考虑荷载影响的氯离子扩散模型是合理的,具有较好的适用性与实用性。     

顺序输送终点混油量近似计算

顺序输送成品油管道在不同油品接触区会产生一段混油,混油量的计算是成品油管输的重要环节。通过对混油浓度的变化规律进行分析,得到浓度变化函数。文中应用雅勃隆斯基-希兹基洛夫湍流扩散系数公式得到终点混油量近似计算公式,并给出相应计算实例。     

海洋环境下基于可靠度的混凝土结构耐久性评估

钢筋锈蚀是造成混凝土结构耐久性失效的最主要原因,海洋环境下导致混凝土结构中钢筋锈蚀的主要因素是C l-侵蚀。本文考虑氯离子的渗透随机过程,建立了海洋环境下结构抗力的随机模型;以桥梁服役状态下,钢筋锈蚀导致结构性能劣化为出发点,运用可靠度分析方法,对海洋环境下钢筋混凝土结构不同时期计入耐久性的承载力进行了分析,并用于某跨海大桥墩柱的耐久性评估。