基于边界元理论模型的舰船腐蚀相关电场衰减规律

基于边界元理论,建立了舰船与腐蚀相关的电场模型,初步研究了舰船腐蚀相关电场在深海环境中随水平距离及深度的衰减规律。结果表明,电场横向分量与垂直分量随纵向距离的衰减速率要大于纵向分量。随正横距离的增加,电场纵向分量与垂直分量的衰减速率逐渐减小,而横向分量为先增大,后逐渐减小。正横距离一定时,电场各分量随深度的增加,衰减速率逐渐减小。     

关于海事行政机关协助法院执行行为的解读

海事行政机关协助法院执行已是一项常态化的工作,由于缺乏明确而具体的规定,导致各海事行政机关在协助执行中的做法不一,且在与法院、当事人之间出现某些不协调、文章从分析协助执行行为性质入手,对海事行政机关协助执行的义务陆、协助执行行为的不可复议性或不可诉性,以及如何协助执行等方面进行了较为全面的解读,对进一步规范协助执行行为,防范协助执行中的执法风险具有较强的针对性生和参考性．     

基于大型高围压界面环剪仪的钢管桩-砂土界面剪切试验研究

为研究不同钢管桩基础与砂土界面剪切特性,研制一种新型桩土界面环剪仪,并基于此设备开展不同围压下钢管桩与均质细砂、福建砂、美国戴维斯砂的界面剪切试验.试验设计压力为200~800 kPa,通过测试分析桩土界面环形剪切时的扭力特征,探究不同桩土界面条件下的剪切应力应变关系.研究结果表明:界面剪切应力随剪切位移增大而增大并趋向稳定,但是在大应变的情况下,界面剪切应力有一定的波动.桩土界面剪切应力拐点对应的剪切位移及界面摩擦角随着法向应力的增加而增加,呈近似线性关系.     

Calibration of nonlinear car-following laws for traffic oscillation prediction

Frequency-domain analysis has been successfully used to (i) predict the amplification of traffic oscillations along a platoon of vehicles with nonlinear car-following laws and (ii) measure traffic oscillation properties (e.g., periodicity, magnitude) from field data. This paper proposes a new method to calibrate nonlinear car-following laws based on real-world vehicle trajectories, such that oscillation prediction (based on the calibrated car-following laws) and measurement from the same data can be compared and validated. This calibration method, for the first time, takes into account not only the driver’s car-following behavior but also the vehicle trajectory’s time-domain (e.g., location, speed) and frequency-domain properties (e.g., peak oscillation amplitude). We use Newell’s car-following model (1961) as an example and calibrate its parameters based on a penalty-based maximum likelihood estimation procedure. A series of experiments using Next Generation Simulation (NGSIM) data are conducted to illustrate the applicability and performance of the proposed approach. Results show that the calibrated car-following models are able to simultaneously reproduce observed driver behavior, time-domain trajectories, and oscillation propagation along the platoon with reasonable accuracy.     

中美英规范在港工水电构筑物结构设计的差异

水电构筑物结构设计是港口工程设计的重要组成部分。以有限单元法为基础,对比中国的GB 50010—2010、美国的ACI 318 M-2014、英国的BS 8110-1:1997这3个规范在港工常规构筑物结构设计中的计算方法,得出中美英规范在港工构筑物的抗弯、抗剪强度、偏心受压强度计算和裂缝宽度、地基承载力验算的异同,并结合典型工程实例说明按照不同规范计算的具体步骤和差异。结果表明,按照美国或英国规范计算的港工构筑物结构的体积含钢量较大。     

On the regimes of underwater explosion for a submerged slender structure by pulsating bubble

Three regimes: near-, middle- and far-fields of underwater explosion are proposed in this study aiming at providing an overview on the responses of submerged slender structure by pulsating bubble. In the near-field, the material starts to yield, thus leading to structure breakdown immediately; remarkable structural global elastic deformation occurs in the middle-field as well as substantial movement; and a structure moves as a rigid body with negligible deformation for the far-field. Equivalent dimensionless parameters are obtained by two different dimensional analysis methods, among which a dominant similarity parameter is found out. Thus, a scaling law providing us with a relation between structural global response and the dominant similarity parameter is yielded, which can be used for demarcating the three regimes quantitatively. To demonstrate, three models corresponding to typical submarine parameters are performed in the case studies. Quantitative criterion of the three regimes is presented along with the regime diagrams. The structural global response features such as the deformation and maximal acceleration/speed of different regimes are provided as well.     

A universal distribution law of network detour ratios

Using trajectory data of normal taxis and ride-sourcing vehicles for 10 cities with various sizes in China, we analyze trip distance characteristics by examining the distribution of network detour ratios. The detour ratio for a specific ride is the ratio of the actual driving distance to the corresponding Euclidean (straight-line) distance. We find that, in spite of their different sizes and geographical features, the various cities exhibit an amazingly similar distribution law of network detour ratios: the mean of the detour ratios is inversely proportional to the Euclidean distance with an intercept. We further verify our findings with extensive simulation experiments for a hypothetical circular city with a directional grid street network. Our finding of this universal distribution law of network detour ratios contrasts sharply with the traditional wisdom of modeling throughout the past 50 years that have typically assumed a constant road detour ratio or factor within the range of 1.25–1.41. Our finding in the urban context also has far-reaching implications for fundamental research in many fields such as human mobility, human geography, facility location problems, logistic distribution networks and urban transportation planning.     

地表注浆对隧道邻近建筑物变形控制规律分析

为了分析地表注浆对隧道邻近建筑物变形控制规律,采用有限元数值模拟方法,从不同层高、与隧道中心线成不同角度、离隧道不同距离等3方面探讨地表注浆加固对建筑物的变形控制规律。研究结果表明：注浆加固对距离隧道中线1～1．5倍开挖跨度范围内地表的沉降控制起到了显著的作用。建筑物与隧道间距离是影响地表注浆加固控制建筑物变形效果的主要因素。建筑物层高越高,距离隧道越远,注浆对周围建筑物作用效果越不明显;随着建筑物与隧道所成角度的增大,作用效果反而越明显。     

美国破产立法的历史变革及现实走向--写在《美国破产法》译后

本文对美国破产立法的历史演变和未来走向作了简要的回顾和考察，并对历次演变及更迭的成因进行了简要的分析。文章第一部分回顾了美国破产法的历史沿革，第二部分分析了美国破产立法的演变特点及成因，第三部分审视了美国破产立法的现实走向。     

刚体平面运动相对瞬时速度及加速度中心动量矩定理的推证

用Ｋａｎｅ方程推证了刚体平面运动时相对瞬时速度中心和瞬时加速度中心的动量矩定理。