公路护坡植被恢复技术探讨

从植物物种的筛选、不同物种的配置和植物的建植技术等3个方面,深入探讨了公路护坡植被恢复技术,研究成果为公路护坡工程实践提供借鉴。     

A Subsection Shared Restoration Method for Long-Haul WDM Networks

A novel restoration scheme, Parted Path Shared Restoration (PPSR), was proposed. The major idea of PPSR is the strategy of ‘parted disposal‘. PPSR keeps the advantage of Path Based Shared Restoration (PBSR) in utilization of capacity. In addition, the restoration time of PPSR is much less than that of PBSR. Furthermore, a satisfaction function was proposed to estimate the performance of PPSR. This function takes the utilization of capacity and restoration time, into a harmonious and uniform frame. Through theoretical analysis and computer simulation, the performance of PPSR was demonstrated.     

高边坡防护技术在港区的综合应用

浆砌防护、预应力锚杆锚索和三维植被网等工艺,常被运用于高边坡防护与加固。以厦门港嵩屿港区采用的高边坡综合加固防护和景观恢复工程为例,介绍浆砌防护、预应力锚杆锚索和三维植被网的主要施工工艺,及采用上述工艺相结合的景观修复措施,并探讨边坡综合防护技术在港区的应用。     

崖州湾中心渔港周边海域岸线修复工程实例

三亚市受台风、暴雨、海水侵蚀等自然因素的影响,沙滩泥化现象日趋严重,海岸线逐渐后退,草坪植被大面积陷落损毁。该市周边部分水上、陆上工程的过度开发建设等人为因素进一步加剧了海岸生态环境的恶化,使崖州湾中心渔港周边海域岸线生态环境受损。以三亚市崖州湾中心渔港周边海域岸线修复工程为例,详细介绍生态底泥疏浚及处理工程、沙滩修复工程、岸线生态修复工程、贝藻礁型丁坝工程四部分内容,完善崖州湾生态整体修复,提升海岸生态功能和防灾减灾功能,解决民生问题,为类似工程提供参考。     

Measuring the performance of airport resilience to severe weather events

The increased severe weather events in recent years as a result of global climate change has created a substantial challenge for aviation system operation. Although transportation engineers and planners have attempted to improve system resilience through the adaptation of new technologies and the implementation of various strategies to achieve effective risk management, it remains unclear how resilience performance (measured by the speed of recovery) of airports varies in different severe weather events and what factors may explain such variations. This paper addresses these fundamental questions using the aviation system in China as an example. A resilience metric, which reflects the speed of recovery (bounce back) from a shock, was developed to measure the performance of airport resilience under various severe weather conditions. In addition, an empirical econometric analysis was conducted based on a dataset that includes both detailed aviation performance and weather conditions for the period of October 2016 – September 2017. The research findings show that airport resilience to severe weather events does vary substantially based on factors, such as weather conditions, airport capacity, and the level of modal substitution. In particular, the recovery time of air services in central and south China tends to be relatively longer in thunderstorms than other weather conditions. The study also confirms that modal substitution is a very effective resilience tactic of the transportation system as the recovery speed of air service was found to be faster by 22.9% if an alternative mode, such as high-speed rail (HSR) service was also available in the city.     

Advancing Coastal Habitat Resiliency Through Landscape-Scale Assessment

Coastal areas are among the most biologically rich regions in the world. They provide tremendous benefit to people through ecological services like pollution filtration, carbon sequestration, and storm protection. However, human activity has decreased the ability of ecosystems to provide these services, and in many coastal areas, restoration is not as effective as it could be. Limited success is largely attributed to vague goals and a lack of holistic, science-informed planning. Quantifying coastal habitat health can aid in setting better restoration goals and lead to greater restoration success. The Long Island Sound Study National Estuary Program conducted the first comprehensive look at coastal habitat health for the Long Island Sound Estuary. In this study we also reviewed landscape-scale habitat assessment progress within other coastal programs. Results can be applied to establish ecosystem health-oriented goals that improve habitat function and resilience across coastal areas.     

Using the Ecopath with Ecosim Modeling Approach to Understand the Effects of Watershed-based Management Actions in Coastal Ecosystems

Resource managers are often tasked with identifying and assessing the potential impacts of management actions on the biotic communities under their care. When the management activities directly influence a single species of interest, managers can turn to a variety of models to aid in their understanding of potential changes to that population. However, as ecosystem-based management becomes more widely accepted, managers will have to understand how proposed actions will impact entire biotic communities, through both direct and indirect mechanisms. Thus, there is a need for ecosystem models that account for both trophic and non-trophic interactions, and that can be relatively easily used to assess a variety of management scenarios. We reviewed the available literature regarding incorporation of eutrophication and other anthropogenic impacts into Ecopath with Ecosim (EwE), one of the more widely used trophic ecosystem modeling frameworks. We found that a number of mechanisms of varying complexity have been used to include these stressors in models, providing managers with a suite of options that can be used to complement their existing management options as they seek to understand the impacts of human interactions on the natural environment.     

海口市南渡江“一江两岸”发展策略

海口市南渡江"一江两岸"主要存在水体浑浊、水系退化、防洪排涝能力不足、景观营造单一、交通联系不畅等问题,制约着两岸建成区的融合发展。重塑"一江两岸"的首要任务是进行生态修复,包括恢复生态湿地、开展水系连通和建设海绵城市等。在恢复生态肌理的同时,构筑"T"字型城市空间发展格局、完善水陆综合交通体系、复合发展滨江产业,助力海口市加快建设国际化滨江滨海花园城市。     

Vehicle scheduling under stochastic trip times: An approximate dynamic programming approach

Due to unexpected demand surge and supply disruptions, road traffic conditions could exhibit substantial uncertainty, which often makes bus travelers encounter start delays of service trips and substantially degrades the performance of an urban transit system. Meanwhile, rapid advances of information and communication technologies have presented tremendous opportunities for intelligently scheduling a bus fleet. With the full consideration of delay propagation effects, this paper is devoted to formulating the stochastic dynamic vehicle scheduling problem, which dynamically schedules an urban bus fleet to tackle the trip time stochasticity, reduce the delay and minimize the total costs of a transit system. To address the challenge of “curse of dimensionality”, we adopt an approximate dynamic programming approach (ADP) where the value function is approximated through a three-layer feed-forward neural network so that we are capable of stepping forward to make decisions and solving the Bellman’s equation through sequentially solving multiple mixed integer linear programs. Numerical examples based on the realistic operations dataset of bus lines in Beijing have demonstrated that the proposed neural-network-based ADP approach not only exhibits a good learning behavior but also significantly outperforms both myopic and static polices, especially when trip time stochasticity is high.     

基于边框匹配的视频差错掩盖技术

以边框匹配技术为基础，提出预掩盖处理、搜索掩盖算法．新算法首先对受损图像区域周围进行预掩盖以期尽可能多地利用周边的有效信息来恢复受损运动向量，最后以估算出的运动补偿块为中心依照边框匹配准则进行搜索，找出最佳运动向量．以JVT(Joint Video Team)测试模型JM(Joint Modal of JVT)1．4为平台的实验表明，改进的掩盖算法在一定程度上能提高重建图像的峰值信噪比(PSNR)值，当与无等待ARQ算法相结合，能在不影响解码器端图像正常回放的情况下，阻止差错的扩散，实现差错图像的完全恢复．