Examining the benefits of using bio-CNG in urban bus operations

Public service fleets offer an attractive option for introducing new renewable fuels on a large scale, which allow for the reduction of both greenhouse gas emissions and exhaust air pollutants. This study examines the use of biomethane (bio-CNG) and compressed natural gas for part of the bus fleet in Dublin, Ireland. The emissions produced from the 2008 fleet based at one of the city’s seven bus depots are compared to use of new diesel and bio-CNG buses. The optimum feedstock for bio-CNG production in Ireland was then investigated, as well as the quantity of feedstock needed to produce the required bio-CNG to fuel the bus fleet examined. As expected the results showed a substantial decrease in all exhaust emissions from the use of bio-CNG buses compared the 2008 fleet. Grass silage was chosen as the optimum feedstock for production of bio-CNG in Ireland.     

Suburban attitudes toward policies aimed at reducing solo driving

Policies that are aimed at discouraging commuters from solo driving have become a part of overall efforts to improve air quality and reduce traffic congestion. Since driving alone is the overwhelming choice of employed residents in US metropolitan areas, the political acceptability of proposed policy changes plays a role in their success. The 1992 Orange County (CA) Annual Survey asked employed solo drivers to rate their likelihood of changing from solo driving in response to various fees and incentives. Fewer say they would be very likely to stop solo driving if they were charged a parking fee at work (20%), a smog fee (17%) or a congestion fee (16%), than if their employers paid them a cash bonus for stopping solo driving (28%), or if more public transit (33%) or more carpools at work (35%) were available. Young and lower-status solo drivers are more likely than others to say they would stop driving alone if there were fees or cash bonuses. Current non-solo drivers tend to be young and low income, providing a validity check on the demographic predictors of stated preferences. The findings are discussed in light of recent policy changes in Southern California.     

Stakeholder Perspectives on the Value of Marine Spatial Planning Towards Advancing Offshore Wind in the U.S.

The United States contributes only 0.2% of the 18,814?MW of global installed offshore wind capacity. Lack of development has been attributed in part to a cumbersome regulatory process that includes the evaluation of environmental impacts. Assessments are based on biological, social, and technical data that are often incomplete. Marine spatial planning (MSP) may help fill data gaps. We conducted semi-structured interviews with key informants to understand (1) whether a lack of biological data impedes offshore wind environmental assessments, (2) whether MSP could mitigate these impediments, and (3) whether MSP could advance offshore wind development in the U.S. in other ways. Most informants stated that a lack of biological data in offshore wind environmental assessments was problematic due to incomplete data, uncertainty of data, and mismatched scales. Data issues may be mitigated by creation of data products and increased communication, outcomes of MSP that may benefit the regulatory process by increasing data availability, resolving conflicts among users, and providing a common operating picture. Challenges remain in integrating MSP into the processes of siting and permitting offshore wind, but it provides a strategic framework for the systematic identification, collection, collation, analyses, application, and management of data in the offshore wind environmental regulatory process.     

Meeting an 80% reduction in greenhouse gas emissions from transportation by 2050: A case study in California

This paper investigates how California may reduce transportation greenhouse gas emissions 80% below 1990 levels by 2050 (i.e., 80in50). A Kaya framework that decomposes greenhouse gas emissions into the product of population, transport intensity, energy intensity, and carbon intensity is used to analyze emissions and mitigation options. Each transportation subsector, including light-duty, heavy-duty, aviation, rail, marine, agriculture, and off-road vehicles, is analyzed to identify specific mitigation options and understand its potential for reducing greenhouse gas emissions. Scenario analysis shows that, while California’s 2050 target is ambitious, it can be achieved in transport if a concerted effort is made to change travel behavior and the vehicles and fuels that provide mobility. While no individual ‘‘Silver Bullet” strategy exists that can achieve the goals, a portfolio approach that combines strategies could yield success. The 80in50 scenarios show the impacts of advanced vehicle and fuels technologies as well as the role of travel demand reduction, which can significantly reduce energy and resource requirements and the level of technology development needed to meet the target.     

Operational impacts of incident quick clearance legislation: a simulation analysis

Many states in the US have enacted quick clearance laws requiring drivers of vehicles involved in minor incidents to move their vehicles from travel lanes prior to the arrival of first responders. Since little is known about the effectiveness of these laws, this research sought to find the benefit–cost ratio of advertising quick clearance legislation to improve driver compliance, and compare it with benefit–cost ratios of other incident management strategies, particularly traffic cameras, freeway service patrols, and traffic sensors. The analysis used traffic simulation that applied application programming interfaces to produce random spatial and temporal occurrence of incidents, including incident start times, durations, and locations, based on normal distributions developed from field data, to test before and after the law scenarios. The results provide decision makers with support for prioritizing funding between these incident management strategies and indicated that investments in the advertisement of this law was beneficial. Copyright © 2011 John Wiley & Sons, Ltd.     

Green supply chain network design to reduce carbon emissions

We consider a supply chain network design problem that takes CO₂ emissions into account. Emission costs are considered alongside fixed and variable location and production costs. The relationship between CO₂ emissions and vehicle weight is modeled using a concave function leading to a concave minimization problem. As the direct solution of the resulting model is not possible, Lagrangian relaxation is used to decompose the problem into a capacitated facility location problem with single sourcing and a concave knapsack problem that can be solved easily. A Lagrangian heuristic based on the solution of the subproblem is proposed. When evaluated on a number of problems with varying capacity and cost characteristics, the proposed algorithm achieves solutions within 1% of the optimal. The test results indicate that considering emission costs can change the optimal configuration of the supply chain, confirming that emission costs should be considered when designing supply chains in jurisdictions with carbon costs.     

以拉力之名2011"MINI拉力趣"

2012年达喀尔拉力赛已经开始,新赛季WRC也即将重燃战火,为配合这两项经典的拉力赛事,MINI首次在国内组织了一场拉力体验活动,让在场的媒体感受到了一种无所不能得MINI精神.     

Modelling minimum-time manoeuvering with global optimisation of local receding horizon control

In this paper, we explore the notion that a human driver uses a receding horizon model predictive control (MPC) scheme for minimum-time manoeuvering. However, MPC is an inherently sub-optimal control scheme because not all future information is incorporated into its finite preview horizon. In many practical applications, this sub-optimality is tolerated as the solution is sufficiently close to optimal. However, it is known that professional drivers have the ability to learn driving circuits and exploit its features to minimise their global manoeuvering time. In this paper, we will model their process with a cascaded optimisation structure. Therein, the inner-loop features a local MPC scheme tasked with finding the control inputs that achieve a blended objective of minimising time and maximising velocity in each preview horizon/distance. The outer loop of this cascaded structure computes the best set of weights for the two components of the local objectives in order to minimise the global manoeuvering time. The proposed cascaded optimisation and control approach is compared against a straight-forward fixed-cost time optimal MPC applied to minimum-time manoeuvering over two well-known race courses. The paper also includes an extended literature review and details of the computational formulation of the model approach.     

A Comprehensive Method for Assessing Marine Resource Governance: Case Study in Kāne‘ohe Bay,Hawai‘i

A recent metaanalysis identified certain management attributes that are associated with successful management of threshold-based systems. However, high variance among case studies indicates that these attributes do not guarantee good conservation outcomes, suggesting that additional factors may be at play. To better understand these additional factors, we compiled a list of effective governance attributes from the literature, and developed guidance for systematically evaluating their presence, absence, and the extent to which each attribute is actually manifested in a given case study. We also examine the distribution of rights and responsibilities within a system, and the resulting impacts on stewardship incentives. Here we present the results of this analysis as applied to Kāneohe Bay, Hawai‘i. Our results confirm that absent or incomplete effective governance attributes can negatively impact conservation outcomes. In Kāneohe Bay, a public-private partnership temporarily compensated for gaps and weaknesses in the governance system, thereby creating conditions conducive to successfully reducing populations of invasive algae. However, this partnership has since dissolved and current capacity to address this and other issues in this system is again lacking. Failure to fix governance weaknesses may compromise the continued health and functioning of the Kāne'ohe Bay system.     

Tributyltin in marine sediments and Philippine green mussels (Perna viridis) in Manila Bay

Tributyltin (TBT) is a pollutant, mainly introduced to the environment as insecticides, fungicides, bactericides, wood preservatives and marine antifouling agent. Concentrations of TBT and its degradation products were isolated from the bivalve Perna viridis and marine sediments collected from selected coastal areas along Manila Bay. In all samples, the extremely toxic TBT compound was detected, calculated as Sn. In sediments, measured concentration ranged from the limit of detection of 0.5 to 9.0 ng Sn g^?1. Highest levels of TBT were observed at the inner and northern part of the bay, adjacent to coastal areas of varying land and water use (i.e., aquaculture, fishpond, mangrove forests, industrial establishments, and ports). However, the levels decrease near the bay entrance. Accumulation in this area can also be deduced from the movement of the prevailing wind and hydrodynamic behavior of the bay during the time of sampling, which transports suspended sediments from the eastern coast of Manila to the northern coast of Bulacan. In green mussels, the levels of TBT ranged from 2.1 to 8.9 ng Sn g^?1. While these values are relatively low, concentrations as low as 0.659 ng Sn g^?1 have been reported to be toxic to molluscs. The environmental levels of organotin species determined in the samples are comparatively low by global standards. Nevertheless, there is a need to estimate the levels of TBT in coastal waters and its associated uses, to evaluate the effectiveness of imposed regulation prohibiting the application of organotin compounds (OTs) as biocides in antifouling agents on ships and aquaculture facilities.