Design trade-offs for energy regeneration and control in vehicle suspensions

This paper investigates the fundamental trade-offs involved in designing energy-regenerative suspensions, in particular, focusing on efficiency of power extraction and its effect on vehicle dynamics and control. It is shown that typical regenerative devices making use of linear-to-rotational elements can be modelled as a parallel arrangement of an inerter and a dissipative admittance. Taking account of typical adjustable parameters of the generator, it is shown, for a given suspension damping coefficient, that the power efficiency ratio scales with inertance. For a typical passenger vehicle, it is shown that there is a feasible compromise, namely that good efficiency is achievable with an inertance value that is not detrimental to vehicle performance. A prototype is designed and tested with a resistive termination and experimental results show good agreement between ideal and experimental admittances. The possibility to use dynamic (rather than purely resistive) loads to improve vehicle control without limiting the energy recovery is discussed. © 2013 Copyright Taylor and Francis Group, LLC.

Effect of dry oxidation on the energy gap and chemical composition of CVD graphene on nickel

The findings presented herein show that the electronic properties of CVD graphene on nickel can be altered from metallic to semiconducting by introducing oxygen adsorbates via UV/ozone or oxygen plasma treatment. These properties can be partially recovered by removing the oxygen adsorbates via vacuum annealing treatment. The effect of oxidation is studied by scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS). As probed by STM/STS, an energy gap opening of 0.11-0.15 eV is obtainable as the oxygen/carbon atomic ratio reaches 13-16%. The corresponding XPS spectra show a significant monotonic increase in the concentration of oxygenated functional groups due to the oxidation treatments. This study demonstrates that the opening of energy gap in CVD graphene can be reasonably controlled by a combination of UV/ozone or oxygen plasma treatment and vacuum annealing treatment. © 2013 Elsevier B.V.

City versus national energy use: implications for urban energy policy and strategies

The global trend towards urbanization means that over half of the world's population now lives in cities. Cities use energy in different proportions to national energy use averages, typically corresponding to whether a country is industrialized or developing. Cities in industrialized countries tend to use less energy per capita than the national average while cities in developing countries use more. This paper looks at existing World Bank data in respect to urban energy consumption, the emissions inventory work done by New York City, and discusses how this data highlights the need for a focus on: energy policy for buildings in industrialized cities; masterplanning and new construction standards in developing cities; and how urban energy policy can become more effective in reducing urban greenhouse gas emissions.

Cost-effectiveness of alternative powertrains for reduced energy use and CO2 emissions in passenger vehicles

This work analysed the cost-effectiveness of avoiding carbon dioxide (CO2) emissions using advanced internal combustion engines, hybrids, plug-in hybrids, fuel cell vehicles and electric vehicles across the nine UK passenger vehicles segments. Across all vehicle types and powertrain groups, minimum installed motive power was dependent most on the time to accelerate from zero to 96.6km/h (60mph). Hybridising the powertrain reduced the difference in energy use between vehicles with slow (t z - 60 > 8 s) and fast acceleration (t z - 60 < 8 s) times. The cost premium associated with advanced powertrains was dependent most on the powertrain chosen, rather than the performance required. Improving non-powertrain components reduced vehicle road load and allowed total motive capacity to decrease by 17%, energy use by 11%, manufacturing cost premiums by 13% and CO2 emissions abatement costs by 15%. All vehicles with advanced internal combustion engines, most hybrid and plug-in hybrid powertrains reduced net CO2 emissions and had lower lifetime operating costs than the respective segment reference vehicle. Most powertrains using fuel cells and all electric vehicles had positive CO2 emissions abatement costs. However, only vehicles using advanced internal combustion engines and parallel hybrid vehicles may be attractive to consumers by the fuel savings offsetting increases in vehicle cost within two years. This work demonstrates that fuel savings are possible relative to today's fleet, but indicates that the most cost-effective way of reducing fuel consumption and CO2 emissions is by advanced combustion technologies and hybridisation with a parallel topology. © 2014 Elsevier Ltd.

Links between energy dissipation and wear mechanisms in solid epoxy/epoxy sliding contact

This paper covers wear and energy dissipation of solid epoxy induced by the alternative rubbing between two samples of identical thermosetting polymer. Varying normal load, sliding velocity and sliding distance, the authors were able to define and discuss wear and friction laws and associated energy dissipation. Moreover, traces of several wear mechanisms were distinguished on the worn surfaces and associated with applied conditions. Observed under higher velocity, polymer softening and local state transition were explained by surface temperature estimate and confirmed by infra-red spectroscopy measurements. To conclude this study, all observed phenomena are classified into two wear scenarios according to sliding velocity. © 2014 Elsevier Ltd.