山区公路路基主要病害的防治

通过多年山区公路养护管理实践,阐述了山区公路路基主要病害的防治措施。     

罐式集装箱计量性能试验分析

分别用几何测量法和容量比较法测试罐式集装箱容积,分析验证几何测量法测试罐式集装箱容积的测量不确定度,确定罐式集装箱容积的计量性能指标。     

成都铁路局系统提升卸车能力的研究与实践

针对近年来成都铁路局运输能力日渐紧张的状况,分析影响区域卸车能力的主要因素:通道输送能力、技术站解编能力、货运站作业能力等,提出通过扩能改造通道输送能力,提升枢纽解编能力和货场作业能力,提高卸车综合能力利用率等对策,以全面提升成都铁路局的卸车能力.     

西部黄土高原区公路交通建设与生态环境保护

根据西部黄土高原区生态环境特征和西部交通建设的特点,提出公路交通建设中面临的主要生态问题,重点对西部交通建设中主要的生态环境问题进行了分析,在此基础上,建议在公路工程建设中应采取的生态环境保护措施。     

The symmetric intersection design and traffic control optimization

It is well recognized that the left-turning movement reduces the intersection capacity significantly, because exclusive left turn phases are needed to discharge left turn vehicles only. This paper proposes the concept of Left-Hand Traffic (LHT) arterial, on where vehicles follow left-hand traffic rules as in England and India. The unconventional intersection where a LHT arterial intersects with a Right-Hand Traffic (RHT) arterial is named as symmetric intersection. It is only need three basic signal phases to separate all conflicts at symmetric intersection, while it at least need four signal phases at a conventional intersection. So, compared with the conventional intersection, the symmetric intersection can provide longer green time for the left-turning and the through movement, which can increase the capacity significantly. Through-movement waiting areas (TWAs) can be set at the symmetric intersection effectively, which can increase the capacity and short the cycle length furthermore. And the symmetric intersection is Channelized to improve the safety of TWAs. The Binary-Mixed-Integer-Linear-Programming (BMILP) model is employed to formulate the capacity maximization problem and signal cycle length minimization problem of the symmetric intersection. The BMILP model can be solved by standard branch-and-bound algorithms efficiently and outputs the lane allocation, signal timing decisions, and other decisions. Experiments analysis shows that the symmetric intersection with TWAs can increase the capacity and short the signal cycle length.     

移动闭塞系统区间通过能力分析及参数计算

移动闭塞条件下“闭塞分区”呈现出“移动”和“长度变化”的特征,其区间通过能力的计算较固定闭塞系统更加复杂。本文建立了移动闭塞系统区间通过能力的数学模型,对区间通过能力与列车追踪运行速度、跟驰车距和列车性能等参数之间的相互关系进行了定性、定量分析,并就关鍵参数的计算方法进行了深入的讨论,对移动闭塞条件下的列车运行控制与行车组织有一定的参考价值。     

Integrating capacity analysis with high-speed railway timetabling: A minimum cycle time calculation model with flexible overtaking constraints and intelligent enumeration

Compared with most optimization methods for capacity evaluation, integrating capacity analysis with timetabling can reveal the types of train line plans and operating rules that have a positive influence on improving capacity utilization as well as yielding more accurate analyses. For most capacity analyses and cyclic timetabling methods, the cycle time is a constant (e.g., one or two hours). In this paper, we propose a minimum cycle time calculation (MCTC) model based on the periodic event scheduling problem (PESP) for a given train line plan, which is promising for macroscopic train timetabling and capacity analysis. In accordance with train operating rules, a non-collision constraint and a series of flexible overtaking constraints (FOCs) are constructed based on variations of the original binary variables in the PESP. Because of the complexity of the PESP, an iterative approximation (IA) method for integration with the CPLEX solver is proposed. Finally, two hypothetical cases are considered to analyze railway capacity, and several influencing factors are studied, including train regularity, train speed, line plan specifications (train stops), overtaking and train heterogeneity. The MCTC model and IA method are used to test a real-world case involving the timetable of the Beijing–Shanghai high-speed railway in China.     

广西高速公路生态环境保护对策研究

文章针对广西高速公路生态环境现状,分析当前高速公路环境保护工作中存在的问题,从生态学角度提出了高速公路沿线生态环境建设和保护对策。     

仿真求解快速路交织区通行能力

由于交织区通行能力的影响因素众多,没有所谓理想的道路条件,而现阶段在我国由于资金、技术等各方面的限制,不能够获得大量的实测数据,因此,用统计分析的方法确定其通行能力有很大的困难。用一个实例详细地介绍了用标定过的仿真软件CORSIM模型求解交织区通行能力的方法、步骤,其中,重点完成了模型freesim-setup中对通行能力有重要影响的8个参数的灵敏度分析,据此标定了仿真模型,然后通过实验方案设计,改变输入条件,得到了不同条件组合下的通行能力值。通过仿真结果与实测数据的对比,认为该方法是非常可行的,并且有一定的应用价值。     

Management of coastal eutrophication: Integration of field data, ecosystem-scale simulations and screening models

A hybrid approach for eutrophication assessment in estuarine and coastal ecosystems is presented. The ASSETS screening model (http://www.eutro.org) classifies eutrophication status into five classes: High (better), Good, Moderate, Poor and Bad (worse). This model was applied to a dataset from a shallow coastal barrier island system in southwest Europe (Ria Formosa), with a resulting score of Good. A detailed dynamic model was developed for this ecosystem, and the outputs were used to drive the screening model. Four scenarios were run on the research model: pristine, standard (simulates present loading), half and double the current nutrient loading. The Ria Formosa has a short water residence time and eutrophication symptoms are not apparent in the water column. However, benthic symptoms are expressed as excessive macroalgal growth and strong dissolved oxygen fluctuations in the tide pools. The standard simulation results showed an ASSETS grade identical to the field data application. The application of the screening model to the other scenario outputs showed the responsiveness of ASSETS to changes in pressure, state and response, scoring a grade of High under pristine conditions, Good for half the standard scenario and Moderate for double the present loadings. The use of this hybrid approach allows managers to test the outcome of measures against a set of well-defined metrics for the evaluation of state. It additionally provides a way of testing and improving the pressure component of ASSETS. Sensitivity analysis revealed that sub-sampling the output of the research model at a monthly scale, typical for the acquisition of field data, may significantly affect the outcome of the screening model, by overlooking extreme events such as occasional night-time anoxia in tide pools.