Impact of environmental assessment and budgetary restrictions in pavement maintenance decisions: Application to an urban network

Road agencies are facing the challenges of aging pavements, deteriorating networks, and insufficient maintenance budgets. This study addresses two limitations in the current state of practice in pavement management. First, because the evaluation of maintenance strategies has traditionally focused on economic and technical aspects, it neglects the environmental impact of maintenance decisions. Second, current management systems often provide a unique, optimised pavement maintenance strategy based on a specific objective(s) and constraint(s). The main objective of the study is to analyse the effect of including environmental aspects and funding availability in the design of maintenance strategies. To achieve this objective, the study followed a three-step methodology. First, this study reviews existing practices on pavement maintenance and the criteria considered to trigger the application of maintenance treatments and their effects on pavement condition. Then, maintenance strategies are optimised considering three levels of budgetary capacity and a sustainable evaluation which incorporates technical, economic, and environmental aspects over the pavement lifecycle. Finally, a case study dealing with an urban pavement network in Chile is analysed. Results obtained from this case study show that an increment of 2% in maintenance budget allows to account for more sustainable maintenance decisions, such as cold in-place recycling and full-depth slab repair, whose greenhouse gas emissions are lower than other alternatives. Results also show that functional asphalt overlay and microsurfacing are more recommended in flexible pavements when budgetary restrictions are low, whereas recommended treatments for rigid pavements exhibit small variability with budgetary restrictions.     

考虑腹地关系的内河港口竞争策略分析

针对上下游两个内河港口之间的竞争问题，考虑相邻港口同时选择单一定价、单一定价-差别定价、差别定价-单一定价和差别定价4 种竞争策略情形下，运用Hotelling 博弈方法，在考虑港口之间水运成本的情况下，对不同竞争阶段港口的均衡价格、市场份额和利润进行了比较. 研究表明：港口的均衡结果与两港的位置和水上、陆路单位运费率之比有关；只有单一港口选择差别定价时，其可以获取更高的市场份额和利润；分别以不同阶段的市场份额、利润作为支付函数，上下游港口的纳什均衡均为差别定价策略.     

基于出行方式决策过程的价格调控策略辅助措施研究

从提高个体在价格调控策略下的绿色出行意向入手，制定价格调控策略的辅助措施是提升价格调控策略有效性的重要手段.本文基于出行决策行为变化自调节阶段模型，构建了价格调控策略下的居民出行方式决策过程概念模型.利用拥堵收费和奖励策略下的出行方式决策心理调查数据，基于结构方程模型，对比分析了拥堵收费和奖励策略下不同机动化出行习惯强度个体通勤与非通勤出行方式决策心理的差异化特征.最后，针对出行方式决策过程中动机形成阶段，计划行为阶段，以及实施计划阶段的心理特征，分别提出了价格调控策略的辅助措施，为价格调控策略实施提供了更好的辅助决策支持.     

船舶油料供受作业监管中存在问题及对策

随着世界航运业的快速发展,我国海域内船舶油料供受业务的不断发展,由于船舶油料供受作业存在较大的污染风险,因此,如何加强船舶油料供受作业监管是海事管理机构必须考虑的问题。文中首先介绍了我国目前船舶油料供受作业监管的法律规定,然后分析了目前船舶油料供受作业监管中存在的主要问题,最后提出了加强船舶油料供受作业海事监管的几点策略。     

中小企业的发展战略选择

随着中国加入WTO和全球经济一体化的持续发展和激烈的市场竞争,使得中小企业将遇到更加严峻的挑战．中小企业要在激烈的竞争环境中生存和发展,必须重视经营战略和创新战略的选择．中小企业的经营战略选择;在产业战略上选择“小而专、小而精”;在市场战略上选择生存互补、协作经营;在竞争战略选择优势互补、联合竞争;在可持续发展战略选择与众不同,经营特色．中小企业的创新战略选择;在体制创新战略上严格按现代企业制度运作;技术创新战略选择引进再创新;管理创新战略上集中于一点就在于知识型管理,建立起学习型组织,运用学习型组织理论管理企业．     

The status of coastal zone management in South Africa

Abstract

In this article, an overview of the status of coastal zone management (CZM) in South Africa is presented. Firstly, it provides background to the development of various initiatives to promote sustainable use of coastal resources within the context of sociopolitical changes in South Africa. Thereafter, it examines the progress made with respect to key attributes underpinning most CZM programs. Finally, it identifies obstacles to achieving effective CZM in South Africa and makes recommendations to address these shortcomings. The review reveals that whilst considerable progress has been made in certain areas of program development, such as resource conservation and pollution control, there are several gaps and inadequacies within existing efforts. These include the absence of a clear policy to guide efforts, lack of coordination amongst government departments involved in CZM, as well as inadequacies in our legal and administrative system. The promulgation of a Coastal Zone Management Act and the establishment of a Coastal Unit charged with the coordination and review of all activities impinging on coastal resources are amongst the recommendations made.     

Learning Frontiers in the Practice of Integrated Coastal Management

Since the Rio conference in 1992 investments in integrated coastal management (ICM) have increased dramatically. National and subnational governments have undertaken many initiatives to protect and develop coastal areas. Extensive field experience has advanced understanding of the operational attributes of ICM. This article reviews the principles and operational attributes of ICM that have become well accepted, particularly from the perspective of international ICM donors and professionals. A common understanding of the fundamentals of ICM provides a base from which targeted and systematic study and assessment of ICM can be conducted. Several thematic areas are suggested where there are currently important needs and opportunities for collective study and learning in ICM. The important role of donors is emphasized in supporting collaborative learning initiatives that advance understanding of ICM, and improve and expand the practice.     

大学英语课堂动机理论研究及Dornyei动机框架的应用

学习动机是影响学习成效的重要因素,本文梳理了心理学领域的动机理论研究的重要成果,将着眼点置于Dornyei的二语动机框架,着重分析了其动机因素三层面的内涵及对我国大学英语教学改革的促进作用。     

Detection and Classification of Vehicles by Measurement of Road-Pavement Vibration and by Means of Supervised Machine Learning

Road vehicle detection and, to a lesser extent, classification have received considerable attention, in particular for the purpose of traffic monitoring by transportation authorities. A multitude of sensors and systems have been developed to assist people in traffic monitoring. Camera-based systems have enjoyed wide adoption over the last decade, partially substituting for more traditional techniques. Methods based on road-pavement vibration are not as common as camera-based systems. However, vibration sensors may be of interest when sensors must be out of sight and insensitive to environmental conditions, such as fog. We present and discuss our work on detection and classification of vehicles by measurement of road-pavement vibration and by means of supervised machine learning. We describe the entire processing chain from sensor data acquisition to vehicle classification and discuss our results for the task of vehicle detection and the task of vehicle classification separately. Using data for a single vibration sensor, our results show a performance ranging between 94% and near 100% for the detection task (1340 samples) and between 43% and 86% for the classification task (experiment specific, between 454 and 1243 samples).