Fleet Efficiency Research Articles

Statistical modelling of ship operational performance monitoring problem

Nowadays, there is a growing expectation to promote operational efficiency of ship fleets in maritime transportation. This study presents a methodical approach basis on statistical learning to model ship performance monitoring problem. It takes the advantage of shrinkage models such as Ridge and Lasso. The demonstrations are conducted through numerical operational features (i.e., fuel consumption, speed, trim, draft, heeling, headwind, etc.) via train and test data set recorded from 2-h voyages of a ferry ship in 2-month period. The findings address to consider trim, pitch, and wind effect. Besides feature selections, both models, which are capable of predicting overall accuracy, learn the relationship between features from the original data set. Comparing to current nonlinear models applied to ship operational performance problems, the Ridge and the Lasso models enable to minimize complexity and to enhance interpretability. Consequently, this study is capable of increasing situational awareness of ship operators (Master and Chief Engineer) and shore-based organizations for monitoring of ship performance. A promising future research may conduct interface designs to transform the continuously monitored features into control actions in terms of ship operational performance management concept.

Factors contributing to technical efficiency in a mixed fishery: Implications in buyback programs

Understanding the factors that define technical efficiency in a fishing fleet is a requirement for the implementation of management strategies, such as buybacks. The goal of this study was to evaluate the efficiency of a semi-industrial fleet operating in the Bank of Campeche, Mexico. The reduction in the catches of main target species necessitates the implementation of management alternatives to reduce the current fishing pressure. A stochastic frontier analysis model was used to evaluate the efficiency and the factors that influence efficiency of four fleet segments defined by fishing gear. Five variables were included: days at sea, crew size, engine power, month and year. Data was retrieved from logbooks that had recorded details of a total of 5497 fishing trips that had taken place during the seasons of 2005, 2012 and 2014. Interviews were also conducted in the Yucatan coast to explore the skippers’ perspectives on the factors that influence fleet efficiency. The results were different between fleet segments, both in estimated efficiencies as significant variables. The difficulty of establishing global targets of fishing effort reduction, through buybacks, for a mixed fleet, with different gears, different target species and different performance is discussed.

The effect of fuel injection equipment on the dispersed phase of water-in-diesel emulsions

Water-in-diesel emulsions are known to lead to micro-explosions when exposed to high temperatures, thereby offering a technology that could improve the mixing of fuels with the ambient gas. The number and size distributions of the dispersed phase have a significant effect on both the long-term stability of the emulsion and the probability of micro-explosion inside an engine. Although the elevated pressures, temperatures, and shear found in high-pressure pumps and common-rail injector nozzles are likely to alter the properties of emulsions, the effect of these engine components on the injected emulsion are not known. To address this issue we sampled an emulsion at several locations within the injection system, from the fuel tank to the injector nozzle, and measured the evolution of the droplet size distribution of the emulsion’s dispersed phase. We varied the water mass fraction (5, 10 and 15% by volume) of the emulsion and the injection pressure (500, 1000 and 1500 bar), imaged the samples using a high-resolution microscope and extracted the droplet size distribution using a purpose-built image processing algorithm. Our measurements reveal that the dispersed droplet sizes reduce significantly after the emulsion is compressed by the high-pressure fuel pump, and again after being injected through the nozzle’s orifices. Additionally, the dispersed droplet sizes measured from the pump’s return and injector return to the fuel tank were also smaller than the initial size, suggesting that the physical and calorific properties of the emulsion in the fuel tank can change significantly with time. Hence we propose that differences in injection equipment and engine testing duration may contribute to some of the disagreements in the literature regarding the effect of emulsified fuels on engine emissions and fuel efficiency. The engine performance and energy efficiency of vehicle fleets that use emulsified fuels will vary with engine running time, thus potentially inducing a drift in the engine performance and exhaust emissions. This investigation also suggests that, in order to be representative of actual injection conditions, fundamental studies of the micro-explosion of emulsion droplets should be performed using much smaller dispersed droplet sizes than those normally found in an unused emulsion.

Prospects for meeting the corporate average fuel economy standards in the U.S.

Efforts to improve vehicle transportation efficiency and curb associated environmental emissions had led to the Corporate Average Fuel Economy (CAFE) standards introduced in 1975 for passenger cars and light trucks. The National Highway Traffic Safety Administration has phased in new standards that require an average combined fleet-wide fuel economy of 48.7–49.7 miles per gallon by 2025. The new legislation has the potential to reduce overall U.S. emissions by close to 6% should the 2025 goals be attained. The goal of this study was to assess the potential for CAFE to achieve the desired average fleet fuel economy goals set forth in the U.S., and evaluate its past effectiveness at reducing actual on-road fuel consumption and associated emissions and environmental impacts. The possibility of the 2017–2025 CAFE standards to be more or less successful than the 2011–2016 standards at meeting fuel economy goals were evaluated together with strategies that auto manufacturers would most likely use to meet the 2017–2025 CAFE standards. The study analyzed transportation efficiency trends, new vehicle sales data, fines paid to date by vehicle manufacturers, and their future projection models. Results demonstrate the effectiveness of the CAFE policy in controlling vehicle fleet efficiency in the U.S. However, the possibility of automakers adapting to presented changes quickly to meet the increasingly strict CAFE standards is unlikely, and cumulative annual fines paid by the industry may reach the order of $700 million by 2025 should current trends continue.

Algorithms and Architectures: A Case Study in When, Where and How to Connect Vehicles

Connected vehicle technologies and applications must coevolve. Existing applications are often suboptimally implemented, stemming from a dearth of design approaches considering resource use, sensor selection, and communication method. Such design tools are necessary to optimize connected vehicle implementations, as applications may have varied impact on individual vehicle and fleet performance, efficiency, and comfort depending on their technical and algorithmic implementation. This paper first introduces several key considerations in connected vehicle design, then explores the implications of varying input richness, connectivity methods, and data availability on an example application predicting automotive idle times. We illustrate common design tradeoffs by evaluating the predictor's accuracy for different implementations, providing developers a look at a design approach that will serve as a useful example framework for future application development. We close with a simplified cost/benefit analysis for our demonstration application to illustrate how feasible, cost-effective application implementations might be identified.

Improving fleet efficiency to maximise economic yield in a Western Australian prawn fishery

The Shark Bay trawl fishery is Western Australia's most valuable prawn fishery (worth AUD$25 million in 2014). The 18-vessel fleet targets western king prawns (Penaeus latisulcatus), brown tiger prawns (P. esculentus) and also retains saucer scallops (Ylistrum balloti) and blue swimmer crabs (Portunus armatus). Increased fuel prices, falling prawn prices and lower catches of other species, following extreme environmental events, have impacted fishery profits. A biomass dynamics model with an economic component indicated that total revenue levels start to decline when annual effort increases beyond ~ 200 fishing days per boat. Annual effort required to achieve MEY, when based solely on prawn fishing, is 115–150 days per boat after accounting for fixed and variable fishing costs and annual fishing efficiency increases of 1–2%. From 2007–2014, the adjusted effort was 188–192 days per boat. Fishing occurred between March and November during 7–8 fishing periods, separated by 5–8day (low catchability) moon closure periods. An empirical daily profit assessment (2007–2015), accounting for recruitment variation, daily prawn size compositions, monthly market prices for different prawn species and sizes, and daily fishing costs, showed vessels made profits on ~ 115–160 days and losses on ~ 15–55 days per year, when fishing occurred near the full moon. The fishery benefitted in 2013–2015 by starting later in the year and better targeting within-season effort. This management strategy within the effort-control framework, which improved profitability, maintained higher spawning stocks and reduced ecosystem fishing impacts, has wider application in prawn fishery management.

Shooting fish in a barrel? Assessing fisher‐driven changes in catchability within tropical tuna purse seine fleets

AbstractWith constant innovation to find more efficient ways to find, catch and process fish, catchability in wild fisheries can increase. Catchability is a combination of resource abundance, fishing effort and fishing efficiency: any increase in fleet efficiency can lead to undesirable effects not only on stocks, but also on the ability to assess them. When using effort controls as part of management, it is necessary to adjust for the increase in catchability due to the increases in efficiency over time to avoid stock depletion. Accounting for changes in catchability can be problematic for pelagic stocks, due to the changes in fishing behaviour and the continual change in fishing efficiency. This study investigates the success in finding patches of fish for fleets operating within the western and central Pacific purse seine fishery between 1993 and 2012. Three indices, widely used in ecological research, were used to study how spatial variation in fisher behaviour for sets on fish aggregating devices (FADs) and free‐school sets was related to catchability. For free‐school set types, the diversity index was negatively correlated with Katsuwonus pelamis catchability. When this index was low, catch rates were at their highest and there was a reduction in the area fished. In contrast, for FAD sets, catches increase when the patchiness index was low, implying a degree of random behaviour, potentially due to advances in FAD technology. An improved understanding of the spatial allocation of effort can improve catchability estimates widely used for fisheries stock assessments and in indices of global biodiversity.

Social and spatial effects of transforming the private vehicle fleet in Brisbane, Australia

Transformation of the motor vehicle fleet has been an important feature of the world’s peak car phenomenon. Very few urban transport studies have explored such important changes in large urban cities. Using an innovative green vehicle datasets constructed for 2009 and 2014, this paper investigates the ongoing change in urban private vehicle fleet efficiency (VFE) in Brisbane. The spatial patterns of VFE change were examined with social-spatial characteristics of the urban area. The results showed that the social and spatial effect of VFE changes remain uneven over urban space. The inner urban areas have experienced higher level of VFE change, whilst people in the outer and oil vulnerable areas showed a low tendency in shifting to more efficient vehicles. The implication of VFE change for future household vehicle adoption was also evaluated based on a cost-benefit analysis of new vehicle technology costs and expected fuel savings for households that choose a fuel efficient vehicle. The results show that imposing a stronger national fuel economy target in the long term would accelerate evolution of vehicle fleets and oil vulnerability reduction in Brisbane.

Evaluation and Testing of Driver-Assistive Truck Platooning: Phase 2 Final Results

Phase 2 final results are described for the FHWA Exploratory Advanced Research project titled Heavy Truck Cooperative Adaptive Cruise Control: Evaluation, Testing, and Stakeholder Engagement for Near Term Deployment, which evaluates the commercial feasibility of driver-assistive truck platooning (DATP). The project was led by Auburn University, in partnership with Peloton Technology, Peterbilt Trucks, Meritor WABCO, and the American Transportation Research Institute. DATP is a form of cooperative adaptive cruise control for heavy trucks (two-truck platoons). It takes advantage of the increasing maturity of vehicle-to-vehicle (V2V) communications (and the expected widespread deployment of V2V connectivity based on dedicated short-range communications over the next decade) to improve freight efficiency, fleet efficiency, safety, and highway mobility as well as reduce emissions. Notably, truck fleets can implement DATP regardless of the regulatory timeline for dedicated short-range communications. The Phase 2 analysis built on Phase 1 and included a testing program of a DATP prototype (with detailed SAE Type 2 fuel economy testing), wireless communications optimization, traffic modeling to understand the impact on roadways at various levels of market penetration, and additional analysis of methods to find DATP partners as well as aerodynamic simulations to understand drag on the vehicles. Detailed analysis of the fuel economy testing data is provided.

Economical driving in the function of increasing the efficency of road transport companies

The main goal of road transport companies, whose activity is transport of goods or passengers, is to constantly increase the efficiency of the resources at their disposal in order to increase the transport market competitiveness. As fuel costs compose one of the largest costs in overall business, their reduction has a significant impact on the final product price. The paper presents the eco - driving significance, that can be used as a toll for increasing the transport fleet efficiency. The driver’s eco - driving training was carried out at the Public transport company in Belgrade by instructors of RICo training centre (Accredited training institute). Analysing the driving parameters before and after training, there were achieved the savings from 9,1% to 20,41% in total fuel consumption, average fuel consumption and average CO2 emissions after training.

Crew awareness as key to optimizing habitability standards onboard naval platforms: A ‘back-to-basics’ approach

BackgroundA healthy habitable environment onboard warships is vital to operational fleet efficiency and fit sea-warrier force. Unique man-machine-armament interface issues and consequent constraints on habitability necessitate a multi-disciplinary approach toward optimizing habitability standards. Study of the basic ‘human factor’, including crew awareness on what determines shipboard habitability, and its association with habitation specifications is an essential step in such an approach. The aim of this study was to assess crew awareness on shipboard habitability and the association between awareness and maintenance of optimal habitability as per specifications. MethodsA cross-sectional descriptive study was carried out among 552 naval personnel onboard warships in Mumbai. Data on crew awareness on habitability was collected using a standardized questionnaire, and correlated with basic habitability requirement specifications. Data was analyzed using Microsoft Excel, Epi-info, and SPSS version 17. ResultsAwareness level on basic habitability aspects was very good in 65.3% of crew. Area-specific awareness was maximum with respect to living area (95.3%). Knowledge levels on waste management were among the lowest (65.2%) in the category of aspect-wise awareness. Statistically significant association was found between awareness levels and habitability standards (OR=7.27). ConclusionThe new benchmarks set in the form of high crew awareness levels on basic shipboard habitability specifications and its significant association with standards needs to be sustained. It entails re-iteration of healthy habitation essentials into training; and holds the key to a fit fighting force.

Leveraging Academic Partnerships to Improve Logistics at Nonprofit Organizations

This article presents the results of a partnership between a nonprofit organization and a team of academic researchers that developed a low‐cost spreadsheet‐based tool that allows organizations to effectively schedule vehicle operations. Specifically, the tool (1) handles the real‐world constraints present in moderately complex logistics environments; and (2) uses general computing hardware and software that is already deployed in most organizations, thereby rendering the solution radically low cost (effectively free). We deployed this tool to a humanitarian organization, the Idaho Foodbank, which realized a substantial improvement in its fleet efficiency and a corresponding reduction in route‐planning time. The methodology used to manage this collaboration with academia can be leveraged by other nonprofit organizations attempting to overcome the financial barriers that commonly prevent budget‐constrained organizations from accessing advanced technologies.

Logística sustentável: avaliação de estratégias de redução das emissões de CO2 no transporte rodoviário de cargas

ResumoO objetivo deste trabalho é avaliar e quantificar o potencial de mitigação de CO2 no transporte rodoviário de cargas decorrente da adoção de medidas e tecnologias voltadas para promover (a) a redução do consumo de combustível, bem como (b) a substituição gradativa do diesel pelo biodiesel. Em cada caso, foi estimada a emissão do cenário base e, em seguida, foram feitas simulações que permitiram construir a curva de emissão em função de avanços tecnológicos voltados para aumentar a eficiência energética ou substituir diesel por biodiesel. Os principais parâmetros utilizados para mensurar as emissões dizem respeito à distância percorrida, quantidade de carga transportada e consumo de combustível. Foram coletados dados primários junto a diversas transportadoras, compondo uma amostra de 145 veículos. Os principais resultados indicam que um aumento de 0,5 km/l na eficiência energética da frota leva a uma redução de cerca de 20% nas emissões de GEE. Entretanto, o potencial de mitigação das emissões através do aumento do teor de biodiesel não é tão promissor, devido, em grande parte, à queda do rendimento do veículo e consequente aumento do consumo. Neste sentido, os resultados apontam que esforços que busquem reduzir consumo de combustível da frota podem contribuir de forma mais efetiva para redução das emissões de GEE que a substituição de percentuais cada vez maiores de diesel por biodiesel.

Did policies to abate atmospheric emissions from traffic have a positive effect in London?

A large number of policy initiatives are being taken at the European level, across the United Kingdom and in London to improve air quality and reduce population exposure to harmful pollutants from traffic emissions. Trends in roadside increments of nitrogen oxides (NOX), nitrogen dioxide (NO2), particulate matter (PM), black carbon (CBLK) and carbon dioxide (CO2) were examined at 65 London monitoring sites for two periods of time: 2005–2009 and 2010–2014. Between 2005 and 2009 there was an overall increase in NO2 reflecting the growing evidence of real world emissions from diesel vehicles. Conversely, NO2 decreased by 10%·year−1 from 2010 onwards along with PM2.5 (−28%·year−1) and black carbon (−11%·year−1). Downwards trends in air pollutants were not fully explained by changes in traffic counts therefore traffic exhaust emission abatement policies were proved to be successful in some locations. PM10 concentrations showed no significant overall change suggesting an increase in coarse particles which offset the decrease in tailpipe emissions; this was especially the case on roads in outer London where an increase in the number of Heavy Good Vehicles (HGVs) was seen. The majority of roads with increasing NOX experienced an increase in buses and coaches. Changes in CO2 from 2010 onwards did not match the downward predictions from reduced traffic flows and improved fleet efficiency. CO2 increased along with increasing HGVs and buses. Polices to manage air pollution provided differential benefits across London's road network. To investigate this, k-means clustering technique was applied to group roads which behaved similarly in terms of trends to evaluate the effectiveness of policies to mitigate traffic emissions. This is the first time that London's roadside monitoring sites have been considered as a population rather than summarized as a mean behaviour only, allowing greater insight into the differential changes in air pollution abatement policies.

US vehicle fuel-efficiency choices: demographic, behavioral, and cultural factors

In the United States, a large proportion of greenhouse gas emissions are from personal vehicle use, and there are large differences in emissions between the most and least efficient vehicles. We use data from 2009 US National Household Travel Survey to characterize consumers who drive the most and least efficient vehicles. We calculate personal fleet efficiency based on all vehicles owned, reflecting the behavioral aspect of vehicle-use choices by owners. Though higher incomes provide the means to purchase more efficient vehicles, we find those with higher incomes more likely to drive low-efficiency vehicles. Higher education levels correlate with greater vehicle efficiency. While some efficiency differences are based on consumer characteristics such as family size, we find large differences that we attribute mostly to cultural preferences as observed by race, region, etc. From a policy perspective, these differences are of particular interest since they may be amenable to change.

Alternative Fuel Vehicle Adoption Increases Fleet Gasoline Consumption and Greenhouse Gas Emissions under United States Corporate Average Fuel Economy Policy and Greenhouse Gas Emissions Standards.

The United States Corporate Average Fuel Economy (CAFE) standards and Greenhouse Gas (GHG) Emission standards are designed to reduce petroleum consumption and GHG emissions from light-duty passenger vehicles. They do so by requiring automakers to meet aggregate criteria for fleet fuel efficiency and carbon dioxide (CO2) emission rates. Several incentives for manufacturers to sell alternative fuel vehicles (AFVs) have been introduced in recent updates of CAFE/GHG policy for vehicles sold from 2012 through 2025 to help encourage a fleet technology transition. These incentives allow automakers that sell AFVs to meet less-stringent fleet efficiency targets, resulting in increased fleet-wide gasoline consumption and emissions. We derive a closed-form expression to quantify these effects. We find that each time an AFV is sold in place of a conventional vehicle, fleet emissions increase by 0 to 60 t of CO2 and gasoline consumption increases by 0 to 7000 gallons (26,000 L), depending on the AFV and year of sale. Using projections for vehicles sold from 2012 to 2025 from the Energy Information Administration, we estimate that the CAFE/GHG AFV incentives lead to a cumulative increase of 30 to 70 million metric tons of CO2 and 3 to 8 billion gallons (11 to 30 billion liters) of gasoline consumed over the vehicles' lifetimes - the largest share of which is due to legacy GHG flex-fuel vehicle credits that expire in 2016. These effects may be 30-40% larger in practice than we estimate here due to optimistic laboratory vehicle efficiency tests used in policy compliance calculations.

Estimating productivity, technical and efficiency changes in the Western Pacific purse-seine fleets

AbstractThe purse-seine tuna fleet in the Western Pacific Ocean has undergone an accelerated expansion since the 1980s. The fishery is primarily managed using fishing effort limits. Constraining effort to ensure the biological health of the stock, while enhancing economic benefits generated by the fishery, is a major challenge faced by fisheries managers in this region. To maintain effort levels that achieve those objectives, there is a need to take into account technical and efficiency changes over time that influence the productivity of fleets. This study evaluates how the productivity of four of the region's purse-seine fleets has changed year on year between 1993 and 2010 using a robust bootstrapped Malmquist index approach. This index is separated into: technical change, which represents the change in productivity due to the introduction of new technology and efficiency change, the change in productivity resulting from a change in the level of efficiency in the use of inputs. The results show that half of the 56 purse-seine vessels examined displayed significant gains in productivity, which appeared to be driven primarily by technical change. The technical efficiency of fleets showed less marked changes, potentially due to the practical inability to maximize performance in the face of dramatic technological advances.

Integrated winter road maintenance management — New directions for cold regions research

The purpose of winter road maintenance is to reduce the negative effect of snow and ice on traffic. The current literature on winter maintenance practices is split into two segments: means of forecasting weather in order to plan proper winter maintenance, and optimization of maintenance operations. There is relatively little literature on the opportunities that real-time information, e.g., from maintenance vehicles, would offer for combining these two segments and taking the applied research and practice one step further. It seems, however, that the lack of operational solutions has so far limited empirical research in favour of analysing prospects that the ubiquitous technologies could offer for winter maintenance. Recent field tests show that the technical obstacles to obtaining real-time information from maintenance vehicles can be overcome. Thus it is possible to enhance the benefits of winter road maintenance operations considerably through new designs and architectures. Improving the efficiency of vehicle fleets by using real-time information is one of the first realizable steps. Based on the analysis of current winter road maintenance ecosystems in several countries, this paper suggests how to make effective use of the transparency that real-time information exchange between different actors can offer. Transparent real-time information enables re-engineering of the entire winter maintenance ecosystem and assists road authorities in setting more precise, and at the same time more diverse, objectives for winter maintenance. This also involves real-time monitoring of service providers' performance and realization of these objectives.

A framework for measuring transport efficiency in distribution centers

Performances of distribution systems are largely affected by the performances of transport systems. This paper is devoted to the analysis of the efficiency of transport subsystems in distribution centers. Transport is a logistics process with the highest energy consumption. In the transport systems two aspects of measuring efficiency are identified. The first aspect is the fleet efficiency which is related to the higher level of decision making. The second aspect of decision making is the vehicle efficiency as operational level of decision making. The main objective of this paper is to propose models for measuring transport efficiency, as well as to identify main factors that affect transport efficiency. The proposed models are based on Principal Component Analysis and Data Envelopment Analysis approaches. According to the results fleet management system, catchment area, vehicle capacity, the age of vehicles and manufacturers are the basic factors that affect transport efficiency.

Fleet design optimisation from historical data using constraint programming and large neighbourhood search

We present an original approach to compute efficient mid-term fleet configurations, at the request of a Queensland-based long-haul trucking carrier. Our approach considers one year's worth of demand data, and employs a constraint programming (CP) model and an adaptive large neighbourhood search (LNS) scheme to solve the underlying multi-day multi-commodity split delivery capacitated vehicle routing problem. Our solver is able to provide the decision maker with a set of Pareto-equivalent fleet setups trading off fleet efficiency against the likelihood of requiring on-hire vehicles and drivers. Moreover, the same solver can be used to solve the daily loading and routing problem. We carry out an extensive experimental analysis, comparing our approach with an equivalent mixed integer programming (MIP) formulation, and we show that our approach is a sound methodology to provide decision support for the mid- and short-term decisions of a long-haul carrier.