Comparative study between Korea and UK: relationship between driving style and real-world fuel consumption

It is known that differences in driving styles have a significant impact on fuel efficiency and driving styles are affected by various factors such as driver characteristics, street environment, traffic situation, vehicle performance, and weather conditions. However, existing knowledge about the relationship between driving style and fuel consumption is limited. Thus, the aim of this study was to analyze the relationship beteen driving style and fuel consumption. The analysis presented in this paper used data from three on-road experiments were conducted independently in two different countries, i.e. South Korea and the United Kingdom. In this study, 91 participants, consisting 44 UK drivers and 47 Korean drivers, were asked to drive approximately 28 km of UK road and 21 km of Korean road, respectively. Driving data, including real-time fuel consumption, vehicle speed, and acceleration pedal usage were collected. The results suggested that driving styles including average vehicle speed and average throttle position were highly correlated with the real-world fuel consumption, and the cultural factors, e.g. road environment, traffic design, and driver’s characteristics affected the driving styles and, consequently, fuel efficiency.     

一种有效近似建模方法及船舶耐波性代理模型构建

船舶耐波性能预报计算过程复杂,会受到诸多设计变量的影响;且采用高精度商业软件如CFD预报船舶性能的计算代价非常高。文章采用拉丁超立方方法进行了设计空间抽样。定义了一个新的综合衡准指标来表达船舶耐波性能,即短期和长期作用下船舶非工作时间百分数。考虑了船舶耐波性能中的五个运动方向：横摇、纵摇、转艏、横荡和升沉。为提高船舶耐波性能计算效率,一种有效的近似建模方法—单参数Lagrangian 支持向量回归算法被用于训练并构建代理模型以预报船舶耐波性能,且该算法是由作者在过去的研究工作中首次提出。以海洋平台支援船（OSV）为例,采用SPL-SVR算法预报船舶耐波性能,并与基于NAPA计算仿真结果、人工神经网络和经典支持向量回归算法进行对比。该文考虑OSV的两种速度,建立了海洋平台支援船短期作用下非工作时间百分数的耐波性能响应面模型,结果显示采用SPL-SVR算法建立的船舶耐波性能响应面模型比较适合船型初步设计的工程实际应用,并具有较高的计算效率。     

Panama Canal expansion: fuel economy and logistical risk

Since cargo capacity increases faster than fuel consumption, the significantly larger capacity fleets which will accompany expansion of the Panama Canal will introduce additional fuel economies and cost savings. Enabling larger, more fuel-efficient vessels to carry cargo the entire distance from Asia to US east-coast ports allows vessel operators to realize significant and meaningful savings compared with the alternatives of using smaller Panamax vessels for the whole distance, or sending the cargo over the US land bridge by train or truck. Fuel savings are quantified along with the monetary savings based on various assumptions for the price of fuel. These savings are dramatic and will increase directly with the price of crude petroleum. Finally, microeconomic theory is deployed to determine how cost savings will be distributed between shipping customers and vessel operators.     

Generation of synthetic datasets for discrete choice analysis

Despite the widespread use of synthetic data in discrete choice analysis, little is known about how the methodology used to generate synthetic datasets influences the properties of parameter estimates and the validity of results based on these estimates. That is, there are two potential sources of biases when using synthetic discrete choice data: (1) bias due to the method used to generate the dataset; and, (2) bias due to parameter estimation. The primary objective of this study is to examine bias due to the underlying data generation method. This study compares three methods for generating synthetic datasets and uses design of experiments and analysis of variance methods to investigate the ability to recover estimates for “true” logsum parameters for nested logit models. The method that uses nested logit probabilities to generate the chosen alternative results in unbiased parameter estimates. The method that is based on Gumbel error component approximations reveals that while the error components themselves are unbiased, subtle empirical identification problems can arise when these error components are combined with synthetically generated utility functions. The method that is based on normal error component approximations reveals that all logsum coefficients are biased upwards; the bias dramatically increases for those nests that have a low choice frequency and is most pronounced for those nests with high correlations among alternatives. Based on the results of the analysis, several recommendations for the generation of synthetic datasets for discrete choice analyses are provided.     

Analysis of the continuous berth allocation problem in container ports using a genetic algorithm

The optimal usage of berths plays a key role in raising the efficiency of container terminals. The berth allocation problem in a container terminal is defined as the feasible allocation of berths to incoming ships such that the total time that elapses between the arrival of the ships to their exit from their berths is minimized. In the transportation literature, the latter problem is usually formulated as a mixed integer programming model. Optimization methods, like the branch and bound algorithm, are efficient ways to solve this model but become absolutely unusable when the size of the problem increases. An advanced search method such as GA may be suited to such a situation. In this paper, a genetic-based algorithm is proposed for the problem. Computational results for two test problems (a small and a large-sized problem) are also presented. The results from the small test are also compared with the results obtained from the branch and bound algorithm.     

Assessment of work-related risk criteria onboard a ship as an aid to designing its onboard environment

The environment onboard a ship presents a typical example of a severe environment, displaying extreme conditions of temperature and relative humidity, especially in the engine room. Datasheets, the international labour organization, and standards do not provide clear information about the suitable ambience of the engine room, its design conditions, and the role of marine engineers in preventing work-related risk. In this study, air temperature and relative humidity were monitored at several locations onboard a merchant ship. These real monitored data were then compared with the ISO design indications to obtain an effective work risk analysis. From these indoor temperature and relative humidity data, the corresponding parameters of thermal comfort in the engine control room and the heat stress and sweating index of a worker in the engine room were determined. As a function of these indices, the maximum time that a worker can stay in the engine room and the time for which he must rest in the control room were also calculated in the present study. Some design corrections are also proposed herein to improve these environments.     

Estimation of CO2 reduction for Japanese domestic container transportation based on mathematical models

This research discusses domestic feeder container transportation connected with international trades in Japan. Optimal round trip courses of container ship fleet from the perspective of CO₂ emission reduction are calculated and analyzed to obtain basic knowledge about CO₂ emission reduction in the container feeder transportation system. Specifically, based on the weekly origin–destination (OD) data at a hub port (Kobe) and other related transportation data, the ship routes are designed by employing a mathematical modeling approach. First, a mixed integer programming model is formulated and solved by using an optimization software that employs branch and bound algorithm. The objective function of the model is to minimize the CO₂ emission subject to necessary (and partially simplified) constraints. The model is then tested on various types of ships with different speed and capacity. Moreover, it is also tested on various waiting times at hub port to investigate the effect in CO₂ emission of the designated fleet. Both the assessment method of container feeder transportation and the transportation’s basic insights in view of CO₂ emission are shown through the analysis.     

Recent Results on Weakly Compact Operators on Banach Lattices

There have been many really positive results concerning the weakly compact operators on Banach lattices in terms of their order structure as well as in many respects. This paper will survey some known recent results in this area.     

Forecasting ridership for a metropolitan transit authority

The recent volatility in gasoline prices and the economic downturn have made the management of public transportation systems particularly challenging. Accurate forecasts of ridership are necessary for the planning and operation of transit services. In this paper, monthly ridership of the Metropolitan Tulsa Transit Authority is analyzed to identify the relevant factors that influence transit use. Alternative forecasting models are also developed and evaluated based on these factors—using regression analysis (with autoregressive error correction), neural networks, and ARIMA models—to predict transit ridership. It is found that a simple combination of these forecasting methodologies yields greater forecast accuracy than the individual models separately. Finally, a scenario analysis is conducted to assess the impact of transit policies on long-term ridership.     

Using Incentives to Reduce Bycatch and Discarding: Results Under the West Coast Catch Share Program

Abstract

Catch share management was implemented in the bottom trawl sector of the West Coast Groundfish fishery in 2011 to address a range of issues including high bycatch and discard rates. The catch share program was designed to remove the incentives to discard through full catch accounting, tradeable quotas, increased flexibility in fishing, and penalties for catch overages. We assess the effectiveness of the program in meeting its environmental objectives by comparing discard weights, proportions, and variability from 2004–2010 with 2011–2016. We analyzed these metrics for species managed using quota, including historically overfished stocks, as well as for non-quota species caught in the fishery. Discard amounts decreased over time for all species and declined to historic lows after the implementation of the program, remaining low through 2016 with much less inter-annual variability. Mean annual discards of two highly-targeted quota species, sablefish and Dover sole, showed the greatest decreases, falling by 97 and 86%, respectively. The discard proportion of overfished quota species fell by 50% on average. The unanticipated decline in discards of non-quota species as well as the decreased variability in discard amounts for all species indicate that the incentives produced by catch share management provided additional ecosystem benefits.