自适应信号控制下交叉口延误计算方法研究

为了研究交通信号的自适应控制方法,需要对交叉口延误进行定量的分析与计算。本文根据信号交叉口理论,在以往定时信号延误研究的基础上,基于交叉口一个进口方向的车辆延误分析,推导了信号控制交叉口不同交通运行状况下的交叉口延误公式;进而对自适应信号控制下交叉口延误的计算方法进行了研究,提出了自适应信号控制下交叉口延误的计算方法———根据交叉口各进口方向不同的交通运行状况以及所处的相序选择相应的公式计算交叉口各进口方向的车辆延误,然后对其求和,得到交叉口延误。     

Balancing energy consumption and risk of delay in high speed trains: A three-objective real-time eco-driving algorithm with fuzzy parameters

Eco-driving is an energy efficient traffic operation measure that may lead to important energy savings in high speed railway lines. When a delay arises in real time, it is necessary to recalculate an optimal driving that must be energy efficient and computationally efficient.In addition, it is important that the algorithm includes the existing uncertainty associated with the manual execution of the driving parameters and with the possible future traffic disturbances that could lead to new delays.This paper proposes a new algorithm to be executed in real time, which models the uncertainty in manual driving by means of fuzzy numbers. It is a multi-objective optimization algorithm that includes the classical objectives in literature, running time and energy consumption, and as well a newly defined objective, the risk of delay in arrival. The risk of delay in arrival measure is based on the evolution of the time margin of the train up to destination.The proposed approach is a dynamic algorithm designed to improve the computational time. The optimal Pareto front is continuously tracked during the train travel, and a new set of driving commands is selected and presented to the driver when a delay is detected.The algorithm evaluates the 3 objectives of each solution using a detailed simulator of high speed trains to ensure that solutions are realistic, accurate and applicable by the driver. The use of this algorithm provides energy savings and, in addition, it permits railway operators to balance energy consumption and risk of delays in arrival. This way, the energy performance of the system is improved without degrading the quality of the service.     

模袋混凝土护坡破损修复施工技术

针对水运工程中模袋混凝土护坡破损修复问题,结合工程实际案例,从设计和施工两方面进行模袋混凝土护坡破损修复施工技术的研究。论述插筋挂模施工设计思路,进行护坡修复稳定分析,综合考虑新浇筑模袋混凝土护坡修复设计,采用打设钢筋、挂模施工,施工方法简单,施工速度快,造价低,解决了模袋混凝土护坡破损修复技术难题。     

Disused shrimp ponds: Options for redevelopment of mangroves

Associated with the rapid increase in the production of cultured marine shrimp has been large‐scale conversion of mangroves to shrimp ponds. Production in many regions has proved to be unsustainable, largely due to inappropriate construction methods, poor environmental conditions, overstocking, and disease. A number of shrimp ponds consequently are unproductive and lie idle. Accurate assessments of pond disuse are difficult to obtain; however, unofficial estimates have suggested that as many as 70% of ponds may be disused after a period in production. Pond construction, shrimp culture, and pond disuse lead to alterations to the physical and chemical properties of soil, hydrological conditions, and the flora and fauna composition of the pond area. The case for restoration, or rehabilitation to a sustainable use, is strong. Consideration must be given to the causes of production failure, the environmental conditions remaining following disuse, the needs and preferences of pond owners and coastal managers, and technical constraints.     

Operating cost based cruise speed reduction for ground delay programs: Effect of scope length

Ground delay programs typically involve the delaying of aircraft that are departing from origin airports within some set distance of a capacity constrained destination airport. Long haul flights are not delayed in this way. A trade-off exists when fixing the distance parameter: increasing the ‘scope’ distributes delay among more aircraft and may reduce airborne holding delay but could also result in unnecessary delay in the (frequently observed) case of early program cancellation. In order to overcome part of this drawback, a fuel based cruise speed reduction strategy aimed at realizing airborne delay, was suggested by the authors in previous publications. By flying slower, at a specific speed, aircraft that are airborne can recover part of their initially assigned delay without incurring extra fuel consumption if the ground delay program is canceled before planned. In this paper, the effect of the scope of the program is assessed when applying this strategy. A case study is presented by analyzing all the ground delay programs that took place at San Francisco, Newark Liberty and Chicago O’Hare International airports during one year. Results show that by the introduction of this technique it is possible to define larger scopes, partially reducing the amount of unrecovered delay.     

张崇段沿线生态工程建设方案

对张崇段沿线的取土场生态环境进行评估和分析,结合不同的地理位置、环境、气候及植被等情况,提出合理的生态恢复建议,可供施工单位和建设单位参考.     

黄土地区公路边坡客土喷播试验研究

陕西黄土地区具有干旱半干旱、半干旱或半湿润的气候特点,土质疏松,公路边坡易被侵蚀。2004年3~9月,禹门口-阎良高速公路采用客土喷播技术,开展了黄土边坡生态恢复试验研究。2004~2006年的观测结果表明,在该地区采取客土喷播技术,能够在公路边坡快速地建立起良好的植被,1年后植被覆盖率可以达到100%。边坡一旦建立植被,只要植物种类配比恰当,植物群落能够保持相对稳定。坡比是影响生态恢复效果的重要因素,有条件的话,宜采用1∶1的边坡。     

厚层基材喷播边坡防护技术研究

干旱半干旱地区高速公路路基边坡植被恢复是目前的一项技术难点。分析了厚层基材喷播的概念、原理、材料组成及施工工艺。通过项目实践,提出了适宜西宁地区厚层基材喷播边坡植被恢复的植物材料紫花苜蓿、柠条、老芒麦、披碱草、中华羊茅、碱茅等,分析了植物选择的原理及适当配比,并阐述了厚层基材喷播、覆盖、后期管护等重点和难点技术。能有效解决石质边坡生态和植被恢复的难题。特别是为在高大边坡或难施工、难养护地区提供了实践性技术指导。     

A macroscopic theory for unsignalized intersections

The following paper presents a dynamic macroscopic model for unsignalized intersections which accounts for time-limited disruptions in the minor stream flow, even in free-flow conditions when the average flow demand is satisfied. It introduces a deterministic fictive traffic light to represent an average alternating sequence of available and busy time periods for insertion depending on the major stream flow. Two allocation schemes of the total outflow during green periods are developed to model the influence or non-influence of the minor stream over the major stream flow. The aggregation of the resulting dynamic flow variations gives relevant capacity values. Moreover, the model predicts accurate average vehicle delay and queue length estimates compared to theoretical and empirical data. It has three easy-to-measure parameters and can be integrated into a dynamic macroscopic simulation tool for urban networks.     

村级河道水生态修复策略与技术措施研究——以闵行区浦锦街道为例

随着国家与公众对乡村生态环境的日益重视,如何对乡村河道进行有效修复成为当前的研究热点.现以闵行区浦锦街道为例,在对其水生态现状调研基础上,解析河道污染特征与污染物来源.并基于绿色生态修复的原则提出了在空间上通过生态缓冲区、河道及植物种植的方式构建河道生态系统的修复思路.进一步根据水体污染特性,制定了底质改良、紫外催化、沉水曝气、底部生物载体、生态浮岛、漂浮草垫、点源净化的内源污染防治技术措施.对比治理前后河道踏勘与水质检测结果显示:治理后河道水生态恢复较好、溶解氧浓度大幅提升、总磷得到了有效控制.后期可根据水体溶解氧浓度对曝气调控以促进对氨氮的去除效果.