顺倾结构面红层岩质边坡稳定性分析及治理

含顺倾结构面的红层岩质边坡开挖过程中极易发生边坡失稳问题。本文以东南地区一公路红层岩质边坡为研究对象,分析该类边坡的致灾因子,并针对该边坡沿顺倾结构面的滑动破坏模式,提出坡脚堆载反压、刷方减载、夯填裂缝、设置排水工程和锚固工程的综合治理措施。通过建立滑坡模型,采用室内试验法、反算法和极限平衡法确定滑面计算参数和滑坡推力,并对治理措施实施过程中边坡稳定性进行分析验算,论证治理措施的可行性。监测数据表明,治理效果较为理想。     

交通建设项目全过程跟踪审计模式探究

结合近几年重点交通建设项目全过程跟踪审计实践,从交通项目跟踪审计的特点、作用、存在问题出发,探讨发展和完善交通建设项目跟踪审计模式需把握的几个问题,在交通项目跟踪审计实践操作和理论发展上作了探索。     

An integrated analysis of workers’ physically active activity and active travel choice behavior

Using Texas add-on sample data from the 2009 National Household Travel Survey, this study examines adult workers’ daily active choice decisions in the context of physical activity and attendant health benefits. The study looked at workers’ two choice behaviors: active activity and active travel. The first choice behavior, active activity, is developed as an ordered-response model based on the number of physically active recreational activities pursued during the workday. The second choice behavior, active travel, is developed as a binary-response model that examines workers’ active travel choices—whether or not the worker used any active mode of travel during the same workday. The study improves the understanding and knowledge of observed factors influencing workers’ physically active activity-travel behavior. The study also provides several observations regarding the role (and constraints) of employment in individuals’ active choices. Using a flexible copula modeling methodology, we explore the true correlation (or dependence) between the two behavior choices that could occur due to the presence of unobserved factors, suggesting a simultaneously low or simultaneously high propensity for being physically active across workers. The study findings suggest that transportation and public health policy makers can mutually benefit from encouraging workers to be physically active (from an activity and/or travel perspective). Overall, the study draws attention to the integrated nature of the public health and transportation fields, thereby providing a distinct view of active/inactive choice behavior. To our knowledge, this is the first study exploring a rich variety of components for workers’ active activity-travel behavior through a robust copula approach.     

The possible designation of the Mediterranean Sea as a SECA: A case study

In view of the ongoing discussions concerning the possible designation of the Mediterranean Sea as a Sulphur Emission Control Area (SECA), a modal split model was applied to a case involving the transportation of consolidated cargoes between Thessaloniki, Greece and industrial hubs of northern Germany. A road-only option was assessed against a combined-transport route involving a ferry (Greece–Italy) and a truck-on-train (Italy–Austria) service. The logit model used considers two variables as determinants of the modal selection: transport cost and time. The data are derived from interviews with a small transport service provider, typical for Greece, and are based on actual trips made (revealed preferences). The results predict that the designation of the Mediterranean as a SECA will cause a modal shift in favour of the road-only route by 5.2%, which under certain assumptions can reach 17.1%. However, the environmental implications of the resulting modal choices, calculated through the EcoTransIT World web based tool, are positive in relation to all emissions examined. This is attributed to the longer distance of the combined-transport option in comparison to the road-only one and, the poor environmental performance of the Ro-Pax vessels basically due to the need to maintain a relatively high speed.     

弄福屯危岩体发育特征及稳定性分析

百色市凌云县弄福屯危岩体发现已久，近年来多次发生零星崩塌掉块现象，严重威胁山下村民的生命财产安全。通过工程地质调查，查明了弄福屯危岩体发育区的工程地质特征，分析了危岩体形成的原因、破坏方式及主要影响因素。根据其破坏方式分别进行稳定性计算，评价危岩体的稳定性并提出治理措施。     

A planar quasi-static constraint mode tyre model

The fast-paced, iterative, vehicle design environment demands efficiency when simulating suspension loads. Towards that end, a computationally efficient, linear, planar, quasi-static tyre model is developed in this work that accurately predicts a tyre's lower frequency, reasonably large amplitude, nonlinear stiffness relationship. The axisymmetric, circumferentially isotropic, stiffness equation is discretised into segments, then parameterised by a single stiffness parameter and two shape parameters. The tyre's deformed shape is independent of the overall tyre stiffness and the forces acting on the tyre. Constraint modes capture enveloping and bridging properties and a recursive method yields the set of active constraints at the tyre–road interface. The nonlinear stiffness of a tyre is captured by enforcing unidirectional geometric boundary conditions. The model parameters are identified semi-empirically; simulated cleat test loads match experiments within 7% including nonlinear stiffness when simulating a flat plate test and a discontinuous stiffness when simulating a cleat test.     

基于直驱阀的快速响应线控制动系统液压力精确控制

为突破响应时间与控制精度的性能瓶颈，提出一种基于直驱阀的快速响应线控制动系统，通过基于Halbach永磁阵列的电磁直线执行器直接驱动阀芯，实现制动轮缸液压力的迅速调节。建立线控制动系统电磁、机械和液压子系统模型，设计基于逻辑门限的线控制动系统液压力-直驱阀位置切换控制架构。压力环采用滑模变结构控制，使轮缸液压力迅速逼近目标液压力值；设计结合摩擦补偿自适应控制律、稳定反馈和鲁棒控制的自适应鲁棒控制方法的直驱阀位置环，使直驱阀芯能够迅速通过阀死区；基于李雅普诺夫函数方法证明算法的稳定性。以线控制动系统的响应时间、控制精度等性能参数作为目标函数，通过相关矩阵分析控制参数对性能的影响规律，并通过多目标粒子群算法优化控制器参数。研究结果表明：提出的切换控制方法与PID控制和滑模控制相比，目标压力10 MPa的阶跃响应时间为0.05 s，稳态误差不超过2％；ARTEMIS欧洲循环工况下的均方根误差为0.33 MPa；设计的直驱阀结构与控制方法有利于提高制动系统的响应速度和控制精度。     

A reduced-order nonlinear sliding mode observer for vehicle slip angle and tyre forces

In this paper, a reduced-order sliding mode observer (RO-SMO) is developed for vehicle state estimation. Several improvements are achieved in this paper. First, the reference model accuracy is improved by considering vehicle load transfers and using a precise nonlinear tyre model ‘UniTire’. Second, without the reference model accuracy degraded, the computing burden of the state observer is decreased by a reduced-order approach. Third, nonlinear system damping is integrated into the SMO to speed convergence and reduce chattering. The proposed RO-SMO is evaluated through simulation and experiments based on an in-wheel motor electric vehicle. The results show that the proposed observer accurately predicts the vehicle states.     

多塔斜拉桥加劲索涡激振动实测与时域解析模态分解

为研究多塔斜拉桥中塔加劲索涡激振动时域和频域特性，对多根加劲索开展了振动加速度测量和风速、风向观测，研究了加劲索振幅与风速和风向的关系，分析了加速度时程的时域和频域特征。采用解析模态分解法对加劲索涡激振动加速度时程进行了分解，分析了所得分量的时域和频谱特征。研究发现，在无雨和较低风速条件下，同侧并列加劲索仅迎风侧发生明显涡激振动，其峰值振动是以频率为6.25 Hz的第28阶模态主要参与为特征，为高阶多模态涡激振动，明显发振风速约为4~5 m·s^-1，风向接近垂直桥轴线，其面内振动明显大于面外。1^#加劲索面内涡激振动时程分解得到的3个相邻高阶频率时程分量显示，第28阶模态振动加速度随时间的变化，主导了加劲索振动加速度幅值的增大和减小。同时认为，解析模态分解法不仅能较好地分离含有多个密集频率分量的时域信号，且分解得到的分量不改变原信号分量的频率特征，分解分量再合成的信号与原信号时频特征完全一致。因而可采用解析模态分解法分解具有多个密集频率分量的柔性结构响应，能有助于工程结构风致响应的模态参数识别。     

放宽条件定点集结模式下编组站车辆集结排队系统分析

集结模式决定了货车集结过程的结束条件，定点集结是一种高效率的集结方式，有利于提高运输质量.针对放宽条件定点集结模式下编组站车辆集结过程，建立离散时间批到达批服务排队模型，利用嵌入式马尔可夫链方法求得离去时刻瞬时系统集结车辆队长分布，并求得任意时刻车辆集结队长分布，在此基础上分别分析了最小编成辆数，车组大小分布，车流到达强度，服务时间间隔分布对车辆平均集结队长，集结延误时间，效率，一昼夜发送车流量等系统指标的影响.分析结果表明，各因素对车辆集结排队系统影响明显.因此，利用本文提出的模型能为编组站的精细化管理和车流组织优化提供决策参考.