Interaction of two three-dimensional explosion bubbles

The interaction of two underwater explosion bubbles was mathematically analyzed in this paper. Based on the assumption of potential flow, high-order curved elements were used to discretize the boundary integral equation and solve it. Assuming that gas inside the bubble follows the isentropic rule, the Euler-Lagrange method was used to trace the evolution of the bubble, and when calculating the singular integral, the singularity of the double-layer singular integral was eliminated by reconstructing a principal-value integral of double-layer potential so that a more precise result could be obtained. Elastic mesh technique (EMT) was also used when tracing the evolution of the bubble interface, and numerical smoothing wasn't needed. A comparison of calculations using this three-dimensional model with results of the Reyleigh-Plesset bubble model shows that the three-dimensional model and calculation method in this paper is practical. This three-dimensional model was applied to simulate the interaction of two bubbles under the action of gravity, and the dynamic characteristics of two bubbles near the surface was also analyzed. Bubbles influenced by surface effects and gravity present severe non-linearity. This paper provides a reference for research into the dynamics of multi-bubbles.     

车削加工切屑卷曲及运动的三维模型研究

对切屑的三维卷曲模型进行了详细的分析，认为切屑具有上卷、侧卷和横卷3种基本的卷曲形式．切屑的运动在加工中是沿着进给方向前进，因此需要对切屑模型向进给方向变换，才能更好地描述切屑在空间的运动形式．切屑运动研究为切屑仿真以及实际加工中控制切屑的形成和折断打下理论基础．     

散货船三维时域波浪载荷计算研究

采用三维势流理论进行船舶运动和波浪载荷预报时,有2种Green函数可供选择:自由Green函数和Rankine源.混合源法,同时使用这2种Green函数,结合了两者的优点.本文对三维时域混合源法开展研究,为了验证该方法的可行性,本文对一艘散货船进行了时域上运动和波浪载荷的计算,并将计算结果转化到频域上以得到RAO.最终把有航速随浪和顶浪工况下该散货船垂向运动和载荷的RAO与WASIM计算结果以及模型试验结果进行比较.比较结果表明,混合源法计算结果与WASIM结果大体一致;在波长较短时,两者计算结果和试验值结果吻合较好,波长较长时两者计算结果都较试验值偏大.随浪海况下2种计算结果较顶浪更贴近试验值.     

条形面板加筋土挡墙拓宽旧路基的三维数值模拟分析

采用ABAQUS软件对条形面板加筋土挡墙拓宽旧路基建立三维弹塑性有限元模型,将新老路基与地基作为一个整体考虑,计算并分析不同工况新旧路基位移与应力分布、面板侧向位移、旧路基变形特征以及筋材应变的变化规律.结果表明,该三维有限元模型能够很好地模拟加筋拓宽路基变形、基底土压力变化、墙面侧向位移以及土工格栅应力应变的分布规律.     

花岗岩的三维网植被护坡技术与工程实践

结合潭市互通及连接线绿化工程实践,介绍风化花岗岩的土壤特性及利用路基表土营造林草生长基质的优点,系统阐述风化花岗岩的三维网植被护坡技术、施工方法及取得的效果,提出了三维网植被护坡技术能快速形成林草植被,绿化固土,是风化花岗岩边坡最优的生态防护方式。     

拱桥三维建模方法

对拱桥结构特点进行分析,依据构造实体几何法理论,提出三维图形变换结合二维面域推移生成三维实体的建模方法,利用Visual C++和ObjectARX工具,通过建模参数,创建封闭图形区域和推移路径,由推移表示法形成桥梁等截面或变截面结构立体,运用平移和镜像等变换方法组装整桥,并以拱桥建模为例实现参数化三维建模,为桥梁三维建模提供新的思路.     

基于三维破坏机制的浅埋硐室塌落面上限分析

鉴于二维破坏机制无法真实反映实际工程中浅埋硐室顶部围岩的三维破坏特征,将二维破坏机制扩展到三维空间中,构建了一种新的浅埋硐室顶部围岩三维破坏机制。通过计算三维破坏机制中的内能耗散功率和外力功率,得到了包含速度间断面方程的目标函数。利用变分法,对该目标函数求极值,得出了浅埋硐室顶部围岩塌落体曲面方程的上限解。在此基础上,绘制了塌落体的三维图像,并分析了塌落体随单一影响参数变化而变化的规律。研究结果表明：当地表荷载较大且支护力较小时,隧道顶部围岩的潜在塌落范围较大,不利于维持浅埋硐室的稳定性。     

柴油机扫气过程缸内流场及其影响因素的数值研究

为了提高6L21/31型船用中速柴油机的经济性和动力性,运用fluent软件的动网格模型对该柴油机扫气过程流场及其影响因素进行了研究,得到了该柴油机扫气过程缸内压力场、温度场、流场随曲轴转角的变化情况和不同因素对其扫气过程影响变化规律。通过分析得到原机在转速不变的情况下,气门重叠角增加5°CA,气缸扫气更充分,有利于提高该机的进气效率,对提高该机的经济性和动力性有利。以上研究可为该机在变工况下工作时功率的提高打下基础。     

基于混凝土损伤塑性本构模型的桥墩仿真分析

由于花瓶墩的体型巨大且几何构型不规则,采用一般的杆系单元方法只能近似分析其力学性能。利用ABAQUS的三维实体单元,分析该墩在组合工况作用下的三维应力分布情况,建立钢筋混凝土损伤塑性本构,计算桥墩混凝土开裂区的钢筋应力,分析混凝土裂缝的分布情况。与杆系单元相比,考虑混凝土损伤塑性本构关系的实体有限元仿真,更能直观精确地显示出非规则性结构的受力及细部裂缝的空间分布情况。     

A three-dimensional risk management model of port logistics for hazardous goods

ABSTRACT

Ports are the distribution centers of hazardous goods in the global transportation system. Once hazardous goods accidents occur in ports, they may cause catastrophic losses to humans and the environment. This research investigates the port logistics risks of hazardous goods and provides an overview of port logistics regarding hazardous goods risks. With this investigation, we conducted a detailed analysis of the underlying causes of the port logistics accidents related to hazardous goods. To manage these risks, this article proposes a three-dimensional risk management model that includes human, governance and goods and provides a risk level identification framework for port hazardous goods logistics. Applying the three-dimensional risk management model, we use the Tianjin port explosion as a case study. Finally, we provide several potential preventative measures to prevent such accidents. The findings of this article contribute to the implementation and monitoring of port strategies that will allow for more sustainable and secure development.