27,833 research outputs found

    Powertrain Architectures and Technologies for New Emission and Fuel Consumption Standards

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    New powertrain design is highly influenced by CO2 and pollutant limits defined by legislations, the demand of fuel economy in for real conditions, high performances and acceptable cost. To reach the requirements coming from both end-users and legislations, several powertrain architectures and engine technologies are possible (e.g. SI or CI engines), with many new technologies, new fuels, and different degree of electrification. The benefits and costs given by the possible architectures and technology mix must be accurately evaluated by means of objective procedures and tools in order to choose among the best alternatives. This work presents a basic design methodology and a comparison at concept level of the main powertrain architectures and technologies that are currently being developed, considering technical benefits and their cost effectiveness. The analysis is carried out on the basis of studies from the technical literature, integrating missing data with evaluations performed by means of powertrain-vehicle simplified models, considering the most important powertrain architectures. Technology pathways for passenger cars up to 2025 and beyond have been defined. After that, with support of more detailed models and experimentations, the investigation has been focused on the more promising technologies to improve internal combustion engine, such as: water injection, low temperature combustions and heat recovery systems

    System configuration, fault detection, location, isolation and restoration: a review on LVDC Microgrid protections

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    Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations, fault detection, location, isolation and restoration

    Carbon Emission Policies in Key Economies

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    The Australian Government asked the Productivity Commission to undertake a study on the ‘effective’ carbon prices that result from emissions and energy reduction policies in Australia and other key economies (the UK, USA, Germany, New Zealand, China, India, Japan and South Korea). The Commissions research report, released 9 June 2011, provides a stocktake of the large number of policy measures in the electricity generation and road transport sectors of the countries studied. And it provides estimates of the burdens associated with these policies in each country and the abatement achieved. While the results are based on a robust methodology, data limitations have meant that some estimates could only be indicative. More than 1000 carbon policy measures were identified in the nine countries studied, ranging from (limited) emissions trading schemes to policies that support particular types of abatement technology. While these disparate measures cannot be expressed as an equivalent single price on greenhouse gas emissions, all policies impose costs that someone must pay. The Commission has interpreted ‘effective’ carbon prices broadly to mean the cost of reducing greenhouse gas emissions — the ‘price’ of abatement achieved by particular policies. The estimated cost per unit of abatement achieved varied widely, both across programs within each country and in aggregate across countries. The relative cost effectiveness of price-based approaches is illustrated for Australia by stylised modelling that suggests that the abatement from existing policies for electricity could have been achieved at a fraction of the cost. The estimated price effects of supply-side policies have generally been modest, other than for electricity in Germany and the UK. Such price uplifts are of some relevance to assessing carbon leakage and competitiveness impacts, but are very preliminary and substantially more information would be required.carbon pricing; cost abatement; greenhouse gas emissions; abatement technology; carbon policy; energy reduction policy; emissions trading scheme; carbon leakage

    Modeling and Real-Time Scheduling of DC Platform Supply Vessel for Fuel Efficient Operation

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    DC marine architecture integrated with variable speed diesel generators (DGs) has garnered the attention of the researchers primarily because of its ability to deliver fuel efficient operation. This paper aims in modeling and to autonomously perform real-time load scheduling of dc platform supply vessel (PSV) with an objective to minimize specific fuel oil consumption (SFOC) for better fuel efficiency. Focus has been on the modeling of various components and control routines, which are envisaged to be an integral part of dc PSVs. Integration with photovoltaic-based energy storage system (ESS) has been considered as an option to cater for the short time load transients. In this context, this paper proposes a real-time transient simulation scheme, which comprises of optimized generation scheduling of generators and ESS using dc optimal power flow algorithm. This framework considers real dynamics of dc PSV during various marine operations with possible contingency scenarios, such as outage of generation systems, abrupt load changes, and unavailability of ESS. The proposed modeling and control routines with real-time transient simulation scheme have been validated utilizing the real-time marine simulation platform. The results indicate that the coordinated treatment of renewable based ESS with DGs operating with optimized speed yields better fuel savings. This has been observed in improved SFOC operating trajectory for critical marine missions. Furthermore, SFOC minimization at multiple suboptimal points with its treatment in the real-time marine system is also highlighted

    Materials Handling Vehicles : Policy Framework for an Emerging Fuel Cell Market

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    © 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association. Open access under CC BY-NC-ND licenseThere are several challenges to wide-spread commercialisation of the technology hydrogen fuel-cell technology; including reliability and cost implications, infrastructure requirements, and safety aspects of the upcoming technology. Targeted policy initiatives are required to address two significant bottlenecks; reliability and cost constraints. Such policy measures and financial mechanisms providing incentives for manufacturers and end-users of the novel technology create an initial impetus for the introduction of the forthcoming technology into the market place. The current approach, policy mechanisms and their impacts are reviewed in the context of demonstration projects, deploying material handling equipment, involving public-private initiatives.Final Published versio

    Development of 3D electromagnetic modeling tools for airborne vehicles

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    The main goal of this project is to develop methodologies for scattering by airborne composite vehicles. Although our primary focus continues to be the development of a general purpose code for analyzing the entire structure as a single unit, a number of other tasks are also pursued in parallel with this effort. These tasks are important in testing the overall approach and in developing suitable models for materials coatings, junctions and, more generally, in assessing the effectiveness of the various parts comprising the final code. Here, we briefly discuss our progress on the five different tasks which were pursued during this period. Our progress on each of these tasks is described in the detailed reports (listed at the end of this report) and the memoranda included. The first task described below is, of course, the core of this project and deals with the development of the overall code. Undoubtedly, it is the outcome of the research which was funded by NASA-Ames and the Navy over the past three years. During this year we developed the first finite element code for scattering by structures of arbitrary shape and composition. The code employs a new absorbing boundary condition which allows termination of the finite element mesh only 0.3 lambda from the outer surface of the target. This leads to a remarkable reduction of the mesh size and is a unique feature of the code. Other unique features of this code include capabilities to model resistive sheets, impedance sheets and anisotropic materials. This last capability is the latest feature of the code and is still under development. The code has been extensively validated for a number of composite geometries and some examples are given. The validation of the code is still in progress for anisotropic and larger non-metallic geometries and cavities. The developed finite element code is based on a Galerkin's formulation and employs edge-based tetrahedral elements for discretizing the dielectric sections and the region between the target and the outer mesh termination boundary (ATB). This boundary is placed in conformity with the target's outer surface, thus resulting in additional reduction of the unknown count
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