Damage assessment of a tunnel-type structure to protect submarine power cables during anchor collisions

The dynamic characteristics of a tunnel structure used to protect underwater power cables, the so-called A-duct, were determined for anchor collisions to provide a procedure for damage assessment and recommendations. The required physical quantities of five target anchors, including the drag coefficient, were obtained using an element-based finite-volume method and ANSYS-CFX software. The terminal velocities of the anchors were then calculated to maximize the colliding kinetic energy. For collision analysis, four parameters (anchor type, ground condition, collision velocity, and collision point) were considered, and the A-duct was modeled based on the Riedel–Hiermaier–Thoma concrete model using ANSYS-Autodyn software. Our analysis results indicated severe damage (D = 1) for most of the gauge points; the damaged area and level increased with the anchor weight. The results showed that the damage was concentrated in the collision area for stock anchors; however, for stockless anchors, damage was also evident in adjacent areas (i.e., damage propagation) due to the anchor head shape as well as the transfer mechanism provided by its reinforcing nets. Accordingly, the 2-ton stock anchor caused more damage at the gauge points near the collision location than the 2-ton stockless anchor. Second, regardless of the ground conditions and rotation angle of the anchor heads with respect to the vertical axis, the damage levels were almost identical. Fixed boundary conditions and non-rotational angle were sufficient for the model used. Third, the damaged areas became smaller when the anchor collision locations deviated from the reference gauge point (P1), i.e., the center of the A-duct. Finally, a comparison of the field-test results to equivalent numerical collision simulations indicated that the size of the predicted and experimentally observed damaged areas were in agreement within 7%.     

Transport infrastructure costs in low-carbon pathways

The rate and manner in which transport infrastructure (e.g. roads, railway tracks, airports) is deployed, will play an important role in determining energy demand, greenhouse gas emissions and the economic impact of the transport sector. This paper describes an exercise where the costs of infrastructure deployment for the transport sector have been incorporated into the IMACLIM-R Global E3 IAM. In addition to adding these costs, the modelling of the criteria for the deployment of infrastructure for roads has also been improved. It is found that this model recalibration results in a more accurate baseline as compared to historically observed data (2001–2013) for investments in energy demand, road infrastructure, and passenger kilometers travelled. Regarding macroeconomic effects, it is found that the imposition of a carbon emission trajectory to 2100 cause GDP to decrease relative to the newly calibrated baseline – this is a standard IAM result. However, when the deployment of infrastructure for roads and air travel is further constrained, the GDP loss is less than with a fixed carbon emission trajectory only. This is because early restriction of infrastructure for roads and air travel allows an expansion of public transport infrastructure which is adequate to meet low-carbon transport service demand whereas when less public transport infrastructure is available, more costly mitigation investments must be made in other parts of the economy. This suggests that restricting infrastructure deployment as a complementary policy to carbon pricing, lowers the cost of mitigation.     

Predictive usage mining for life cycle assessment

The usage modeling in life cycle assessment (LCA) is rarely discussed despite the magnitude of environmental impact from the usage stage. In this paper, the usage modeling technique, predictive usage mining for life cycle assessment (PUMLCA) algorithm, is proposed as an alternative of the conventional constant rate method. By modeling usage patterns as trend, seasonality, and level from a time series of usage information, predictive LCA can be conducted in a real time horizon, which can provide more accurate estimation of environmental impact. Large-scale sensor data of product operation is suggested as a source of data for the proposed method to mine usage patterns and build a usage model for LCA. The PUMLCA algorithm can provide a similar level of prediction accuracy to the constant rate method when data is constant, and the higher prediction accuracy when data has complex patterns. In order to mine important usage patterns more effectively, a new automatic segmentation algorithm is developed based on change point analysis. The PUMLCA algorithm can also handle missing and abnormal values from large-scale sensor data, identify seasonality, and formulate predictive LCA equations for current and new machines. Finally, the LCA of agricultural machinery demonstrates the proposed approach and highlights its benefits and limitations.     

An integrated risk assessment model: A case of sustainable freight transportation systems

The major challenge in the development of sustainable freight transportation systems (SFTSs) is due to the involvement of numerous dynamic uncertainties and intrinsic sustainability risks. Sustainability risks are potential threats that can have undesirable impacts on the sustainability of a system. The main objective of this study is to identify and evaluate the sustainability risks associated with freight transportation systems (FTSs). Accordingly, a risk analysis approach is developed by innovatively integrating the intuitionistic fuzzy set theory and D-number theory to quantitatively model the sustainability risks. Intuitionistic fuzzy numbers can examine both the membership and non-membership degrees of an element while the D-number theory increases the objectivity of assessments by fusing multiple expert judgments. The proposed risk assessment model facilitates the managers in the development of SFTSs by ensuring visibility, predictability and measurability in freight operations. Unlike the conventional perception, the findings indicate that most of the high priority sustainability risks in FTSs are socially induced rather than financially driven and consciousness in people’s conduct is must to attain the positive results. The analysis alerts the freight managers toward the high priority sustainability risks and guides in pro-active strategy formulation and optimum allocation of mitigation resources to minimize disruptions in SFTSs.     

智能网联汽车全生命周期节能减排绩效评价研究

为进一步研究不同级别智能网联汽车全生命周期节能减排绩效,基于生命周期评价方法(LCA),以某国产合资紧凑型纯电动乘用车为评价对象,搭建智能网联汽车生命周期评价模型,研究分析其全生命周期的矿产资源消耗、化石能源消耗及环境排放影响;进而基于不同级别智能网联汽车采用智能装备的差异,对L0~L5级别智能网联汽车全生命周期各阶段能源消耗和环境影响进行评估预测与对比分析。研究结果表明：在智能网联汽车全生命周期矿产资源消耗方面,原材料获取阶段占比最高;在化石能源消耗方面,运行使用阶段占比最高;在综合环境影响方面,受中国电力结构影响,运行使用阶段环境影响综合值最大;随着智能化程度的不断提高,智能网联汽车相邻级别间全生命周期化石能源消耗可降低3.5%~6.3%,GWP、AP、EP、POCP环境排放最高可分别降低约13.9%、13.3%、13.7%、11.7%,其中使用阶段环境排放降低程度最为明显;综上,通过进一步加强汽车轻量化研究,拓展新型材料在智能网联汽车领域的应用,合理优化我国电力结构布局,提升车辆自主决策水平,加快云平台与大数据等关键技术在智能网联汽车上的应用等途径,可有效提升智能网联汽车节能减排效果。     

考虑衬砌渗透性的盾构下穿既有隧道纵向结构错台变形研究

目前针对盾构开挖下穿既有隧道的解析理论研究一般基于Winkler地基模型,且未考虑既有隧道衬砌渗透特性,常常忽视地基剪切变形和既有隧道渗漏水的影响。基于体现土体剪切特性的Pasternak地基模型,首先计算了既有隧道渗漏水影响下盾构开挖在既有隧道轴线处产生的附加荷载。在此基础上,通过能量变分法建立由抗拉弹簧及剪切弹簧共同连接相邻管片环的既有隧道变形模型,获取隧道纵向结构剪切错台响应规律。选取多个工程实例,将理论解析结果与现场实测数据进行对比后发现,考虑地基剪切变形及既有隧道渗漏影响的理论解析结果更加贴近实测数据。此外,针对既有隧道异常渗漏区间渗漏程度、异常渗漏范围、异常渗漏位置进行了影响因素分析,并依据环间错台量及环间转角对既有隧道进行安全等级评估。通过参数分析发现：随着异常渗漏区间衬砌渗漏程度的增大,既有隧道纵向结构变形显著增大,当异常渗漏区间衬砌-土体相对渗透系数为0.1时,已有小范围环间错台量及转角被纳入安全评估等级Ⅲ;随着异常渗漏范围的扩大,既有隧道纵向结构变形增大,更大范围的环间错台量及转角达到安全评估等级Ⅲ;异常渗漏位置向远离新建隧道中心轴线方向发生偏移,既有隧道纵向变形逐渐减小,纵向结构变形峰值沿异常渗漏位置偏移方向发生偏移。     

基于突变级数法的桥型方案适应性评价

目前在桥型方案比选的工程实践中,还较少通过方案适应性的评价以达到优选桥型方案的目的。本文在相关研究基础上,提出了桥型方案适应性评价的指标体系,并且结合突变理论,建立了基于桥型方案适应性评价的桥梁方案选型的突变级数法。首先对桥型方案评价目标进行多层次分解及评价指标属性值数据的归一化处理;然后根据相应的突变数学模型计算突变模糊隶属函数值;最后计算总突变级数值,据此对桥型方案进行优选。实例研究表明,该方法可靠性高、客观性强,为工程实践中桥型方案选型提供了新思路和途径。     

船舶撞击后导管架安全性评估修复的方法探讨

依托项目实例,以实测凹陷值来还原撞击荷载,进而对导管架进行剩余强度评估和其它部位的损伤筛查,给出导管架海上维修方案,结合对平台的整体安全性评估结果,给出修复方法和后期监测方案。     

基于雷达红外复合信息的目标毁伤评估技术研究

防空导弹击中目标后,指控系统实时快速判断该目标是否被有效毁伤,是系统释放该目标通道的前提。通过分析序列红外图像中目标不变矩特征的变化,可对武器爆炸瞬间对目标所产生冲击和损伤进行评估;通过基于雷达测量空中目标有关运动学参数,建立目标运动状态变化的参量模型,根据目标视航角与加速度变化相结合的判别方法,可得出目标被有效毁伤的判据。论文提出了一种基于雷达红外复合信息的目标毁伤评估技术的流程和实现方法,并通过仿真初步验证了该方法的有效性。     

模糊神经网络在船舶电力推进系统状态评估中的应用

船舶电力推进系统状态评估是状态检修的前提和基础,建立科学、全面、合理的评估指标体系,选择合适的评估方法,并最终开发切实可行的状态评估系统是船舶电力推进系统状态评估的必要步骤。提出船舶电力推进系统状态评估的流程、基于模糊神经网络的船舶电力推进系统状态评估模型和具体评估步骤,结合船舶电力推进系统的实船运行数据进行状态评估模型仿真试验。仿真试验结果表明,模糊神经网络方法应用于船舶电力推进系统的状态评估具有一定的准确性。