橡胶沥青的输送和计量

橡胶沥青作为道路工程中的高温、高粘度介质,想要成功地将其泵送可能并不容易,而进行橡胶沥青的计量则更具挑战性。由于胶粉的磨蚀性,使用机械式的齿轮流量计已被证明是不可靠的。因为随着时间的推移,胶粉对齿轮的磨损会造成啮合齿轮打滑,由此造成的测量误差会超过精度许可范围。     

Spillover effects and dynamic correlations between spot and forward tanker freight markets

Monitoring and analysing information transmission across different shipping markets is an important tool for participants to predict shipping freight rates, design portfolio investments and manage freight rate risks. The purpose of this article is to investigate spillover effects and dynamic correlations between shipping spot and derivatives markets (tanker forward freight agreement, FFA) under the multivariate generalized autoregressive conditional heteroscedasticity framework. Empirical results show that spillovers in returns are unilateral from one-month FFA to spot markets, while they are bilateral between one-month and two-month FFA markets. However, insignificant mean spillovers between spot and two-month FFA markets are found. Volatility spillover effects among one-month FFA, two-month FFA and spot freight markets are bilateral. By analysing the correlation between different markets, highly persistent and significantly volatile correlations are found. Moreover, time-varying correlations between one-month and two-month FFA markets are much higher than those of between spot and each FFA market. Results from this article will be helpful to improve participants’ predictions of return, volatility and correlation, which are significant for determining hedge strategies. In addition, the management of freight rate risk and portfolio investment can also benefit from the empirical results obtained in this article.     

IAME 2011 – contemporary studies on maritime transport in Latin America

Latin America and the Caribbean have evolved as a region of increased interest for the maritime and port industry as well as for academic research. Maritime transport activity in the region has experienced sustained growth rates over the last decades, resulting in ever-increasing demand for maritime services and port infrastructure. At the 2011 Annual Conference of the International Association of Maritime Economists (IAME), Latin America received significant attention. This editorial responds to growing research by giving a brief overview of the current situation and contemporary issues in maritime transport within the region. It also introduces the six selected papers for this Special Issue.     

Who's using Biffex? Results from a survey of shipowners

The continued survival of the Baltic International Freight Futures Exchange (Biffex) would certainly have come as a surprise to many critics that were present at its inauguration. In an effort to explain, at least partially, the reasons for its continued existence, this paper presents the results from a behavioural and attitudinal survey of shipowners. Through the analysis of the responses received, the paper attempts to evaluate the degree of success achieved by Biffex in providing shipowners with a powerful, flexible and viable mechanism for hedging their market risk. The results imply that there is great scope for improving the acceptability of the market amongst shipowners, particularly as a hedging tool. In the light of these results, the paper comments on potential future innovations within Biffex and suggests changes in marketing policy that might lead to an increased level of acceptance amongst shipowners. In conclusion, recommendations are made with respect to aspects of Biffex that are worthy of further investigation and analysis.     

Psychological benefits from vanpooling and group composition

Prospective carpool satisfaction varies with respect to carpool size, acquaintanceship and gender composition, at least for carpool arrangements of 2–4 members. It is not known whether such variations apply in the same kind or to the same degree for vanpools of 9–15 members. A study of 15 vanpool programs in Southern California operating over 700 vanpools with more than 8,000 members was used to test for such effects. Five measures of retrospective vanpool satisfaction were derived from 40 vanpool benefit items using factor analysis in LISREL. The five perceived vanpool satisfaction factors included reliability, social, relaxation, economic and environmental benefits. Variations in these five benefit factors were analyzed with respect to vanpool group composition using difference of means tests and correlation analysis. Perceived vanpool reliability showed the largest statistical association with most of the group composition variables studied, perhaps because it was better identified in the analysis in terms of the total number of individual items loading on it. Gender had the largest statistical association with most of the vanpool benefit factors, perhaps because it was most clearly identified with individual vanpool members in the data. Based on this analysis, it appears that perceived vanpool benefits are qualitatively as well as quantitatively different than perceived carpool benefits. Vanpool program marketing strategies may need to be rethought and recast based on these research findings.     

A reverse causal-effect modeling approach for signal control of an oversaturated intersection

A novel approach is presented in which signalized intersections are treated as normal highway bottlenecks for improved computational efficiency. It is unique in two ways. First, it treats the signalized intersections as common freeway bottlenecks by a reversed cause and effect modeling approach. Both traffic arrivals and departures are modeled by smooth continuous functions of time as if there were no interruptions to traffic flows from signals. The use of smooth continuous functions for departure curves instead of commonly used step functions makes it easy to apply differential calculus in optimization and future extension to a system of intersections. Second, a dynamic linear programming (LP) model is then developed to maximize the total vehicular output from the intersection during the entire period of congestion subject to prevailing capacity and other operational constraints. The continuous optimal departure flow rate (the effect) is then converted to signal timing parameters (the cause) that can be readily implemented. Two numerical examples are presented to demonstrate the properties of the proposed algorithm and examine its performance.     

旧金山-奥克兰海湾桥抗震安全设计

美国奥克兰海湾桥位于州际公路上,1936年通车.为上下行分离桥面,共10条车道,每天有超过28万辆车通过.Loma Prieta地震造成E9号墩上的两跨双向桥面部分坍塌.新建东跨奥克兰海湾桥项目由四个不同结构组成,第一部分从奥克兰到Yerba Buena岛,为奥克兰部分;第二部分以"高架桥"闻名,是一个平行的混凝土箱梁结构;第三部分为自锚式悬索桥,是当前在建的主要结构;最后一部分是一系列多室后张拉箱梁桥.本文将着重对东奥克兰海湾大桥新建项目为震后"生命线服务"进行的设计和施工进行论述.     

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.     

Logistics as a driving force for development under the Belt and Road Initiative – the Chinese model for developing countries

ABSTRACT

An important objective of “the Belt and Road Initiative” is to promote the economic growth of countries in the region. China’s successful development experience, proposed in the initial stage of reform, can be summarised as “Looking for development, building the highway first”. This study is the first to evaluate whether logistics infrastructure has indeed contributed to economic growth by employing an error correction model with panel data from 2003 to 2014. In addition, we compare the influence levels of different sectors of logistics infrastructure in different regions, i.e. developed and developing regions. We focus on developing regions as they represent good development experiences for developing countries in the Silk Road Economic Belt. For developing regions, we find that the most influential factors are telecommunication and airway transportation, which should be the foci of attention in order to promote economic growth and reduce inter-region economic inequalities. The research confirms that logistics is indeed a driving force for economic growth in China, and that the contributions of specific sectors can be a useful reference for developing countries to determine prioritisation of investment in different logistics sectors across regions.