新疆公路三级区划中环境参数的提出

自然环境条件对公路工程的影响，主要体现在路线选取、路基强度和稳定性、路面稳定性和耐久性、公路主要自然病害(包括冻融、翻浆、雪害、风沙害、崩塌、滑坡和地震灾害等)、施工条件和养护运营环境等5个方面，分析自然条件和公路工程的关系，提出公路区划中地质地貌环境参数和水热状况环境参数。阐述了环境参数的提出过程，为新疆公路自然区划三级区的划分提供依据。     

计算机仿真研究平整度指标与路面状态的定量关系

参照平整度测量仪的结构及原理,用MATLAB科学计算语言对平整度的测量过程进行了模拟仿真,分析平整度指标与路面状态参数之间的定量关系,并阐述了此项研究对提出新的摊铺机自动找平系统的控制方式,提高路面平整度具有的实际意义与可行性.     

Urban walkability considering pedestrians’ perceptions of the built environment: a 10-year review and a case study in a medium-sized city in Latin America

ABSTRACT

Numerous methodologies measuring walkability have been developed over the last years. This paper reviews the Walkability Index (WI) literature of the last decade (2009–2018) and highlights some limitations in the current approaches. Only a few studies have evaluated walkability in Latin America, mainly in big cities but not in medium and small-sized cities in the region, which present their own urbanisation dynamics, security issues, sidewalk invasion problems, and poor planning. Furthermore, most WIs in the literature use objective mesoscale variables to assess walkability in a given area. This paper contributes to filling these gaps by generating new evidence from a medium-sized city in Latin America to question if characteristics of the built environment encourage walking trips, as found in the literature, are transferable among regions. The study also proposes a novel index comprised of microscale and mesoscale built environment variables to assess walkability using virtual tools and considering users’ perceptions. The WI estimation relies on ranking probability models. The results of the case study suggest that subjective Security and Traffic Safety are the most crucial factors influencing walkability in these kind of cities, which is different from what is found in the literature from cities in developed countries where Sidewalk Condition and Attractiveness are the most important factors. Security appeared to be strongly associated with a subjective dimension, represented by the fear of crime or perceived risk for crime, instead of the actual occurrence of crimes. This result evidences the importance of the physical attributes of the real world and how they are captured, judged, and processed by pedestrians. Then, regional transferability of WIs needs to be done carefully. Finally, results in this paper highlight the importance of microscale built environment characteristics in the WI formulation in these cities. Results are in line with other research in some cities of the region, which found that microscale variables such as pavement quality and presence of obstacles on the sidewalks are relevant components to promote walkability.     

Time-variant bulk carrier reliability analysis in pure bending intact and damage conditions

Time-variant reliability analysis of a corroded bulk carrier in intact and damage conditions is performed by First-Order (FORM), Second-Order (SORM) Reliability Methods and Importance Sampling simulation. Annual failure probabilities are determined up to 25-year ship lifetime, accounting for time-variant corrosion wastage of structural members contributing to hull girder strength. Statistical properties of hull girder capacity are determined by Monte Carlo simulation, applying three correlation models among corrosion wastages of structural members contributing to hull girder strength, namely no correlation, full correlation and full correlation among wastages of structural members belonging to the same category of compartments. A modified incremental-iterative method is applied, to account for instantaneous neutral axis rotation, in case of asymmetrical damage conditions, as for collision and grounding events. Incidence of intact/damage condition, as well as correlation among corrosion wastages, on annual sagging/hogging time-variant failure probability is investigated and discussed. Time-variant sensitivity analyses for intact and damage conditions are also performed, to investigate the incidence of random variables' uncertainties on the attained failure probability. Finally, the bulk carrier section scheme, benchmarked in the last ISSC Report, is applied as test case.     

隧道工程建设地质预报及信息化技术的主要进展及发展方向

复杂的不良地质条件是制约隧道安全高效建设的主要因素,要实现隧道工程的安全高效建设,首先要提高地质预测预报技术水平及其信息化程度。1)介绍我国复杂不良地质隧道超前预报的方法进展及其应用,包括突水突泥灾害源超前探测方法与设备、断层破碎带超前预报、城市地铁溶洞和孤石等探测的进展及应用等;2)介绍我国隧道岩爆监测预警方法及其应用,预报清楚之后就要加强安全风险过程监控;3)介绍基于BIM技术的建筑物(隧道工程)安全风险监控最新进展,包括安全风险实时感知系统和实时预警系统;4)指出隧道工程建设信息化技术的发展方向,包括开展基于大数据技术的TBM/盾构施工的分析与控制研究以及数字隧道向智慧隧道(建设和运营维护)的发展。     

高黎贡山隧道复杂地质条件下敞开式TBM施工关键技术研究

高黎贡山隧道地质条件极其复杂,可总结为"三高四活跃"。其中,高地热、高地应力、多断层破碎带、高压突涌水是制约TBM施工质量和安全的主要地质因素,将给TBM施工带来不可预估的风险。为了减少以上地质问题带来的TBM施工风险,通过资料查阅、调研国内外现有的TBM施工案例、专家咨询研讨、设计高适应性的TBM,并结合工程目前的施工状况,提出了TBM超前地质预报、钢筋排和钢拱架联合喷射混凝土及时支护、合理调整掘进参数等一系列确保TBM连续施工的方案与措施。研究结果可为即将进场施工的TBM提供理论参考。     

Vehicle lift-off modelling and a new rollover detection criterion

The modelling and development of a general criterion for the prediction of rollover threshold is the main purpose of this work. Vehicle dynamics models after the wheels lift-off and when the vehicle moves on the two wheels are derived and the governing equations are used to develop the rollover threshold. These models include the properties of the suspension and steering systems. In order to study the stability of motion, the steady-state solutions of the equations of motion are carried out. Based on the stability analyses, a new relation is obtained for the rollover threshold in terms of measurable response parameters. The presented criterion predicts the best time for the prevention of the vehicle rollover by applying a correcting moment. It is shown that the introduced threshold of vehicle rollover is a proper state of vehicle motion that is best for stabilising the vehicle with a low energy requirement.     

柴油机起动过程缸内窜机油现象的可视化研究

在单缸机上利用内窥镜技术观察到了起动过程中缸内有窜机油的现象。采用图像分析和试验验证相结合的方法,分析了缸内窜机油现象发生的原因,研究了转速和进气压力对柴油机起动倒拖工况下缸内窜机油现象的影响,研究了起动着火运行时缸内的窜机油现象以及炭烟排放特性。研究表明:柴油机高转速起动倒拖工况下,在压缩上止点前后以及排气上止点后均有机油窜入缸内;当转速升高时,窜入缸内的机油量增加;当缸内压力升高时,窜入缸内的机油量减少;在起动着火过程中,运行初期缸内出现窜机油现象,随着发动机运行时间增加,窜机油现象消失,炭烟减少。     

立交线形动态拖动设计的关键技术

对立交线形动态拖动设计的几个关键技术进行论述.分析了缓和曲线计算精度,提出了动态拖动模式设计模型,以及约束满足条件下的非线性方程组的数值解算法.     

HMI-���п���·��ͨӵ�µ�һ��Ԥ��ָ��

借鉴定性推理中描述参数的相关方法,首先提出了描述城市快速路各车道交通流同态程度的概念——同态度量指数（Homogeneous Measure Index ,HMI),大量对快速路的实证研究得到的HMI指数反应了不同情况下交通流状态的定性差异。通过对北京环路交通拥堵发生与消散过程的观察和分析,本文发现当交通拥堵发生或消散的过程被触发时,不同车道交通流的同态度量指数HMI会发生定性跃迁变化,并且各车道交通流的同态性变化将是一个“同态 非同态同态”的过程,因此可以利用这一性质,将HMI作为一个指标来对城市快速路交通拥堵是否可能发生进行预警。