Surface plasmon resonance-based gas sensor with chalcogenide glass and bimetallic alloy nanoparticle layer An extension of the Mie ͓Ann. Phys. 25, 377 ͑1908͔͒ theory for the calculation of optical absorption spectra in bimetallic nanoparticles has been developed. The nanoparticle dielectric function is assumed to be a weighted linear combination of dielectric functions for single particles. Accordingly, analytical expressions for the resonance light absorption frequency, the spectrum maximum value, and the full width at half maximum have been derived, taking into account the interband transitions in the dielectric functions. Experiments have been performed on polymer-embedded Ag/ Au nanoparticles prepared by reducing the presence of poly͑vinyl pyrrolidone͒ at room temperature. Experimental absorption spectra have been compared to numerical curves derived by the model in the case of Ag/ Au systems at different relative compositions, and they are in good agreement. The time dependence of both Ag/ Au nanoparticle size and chemical composition during the growth process has also been investigated.
An effective method of preparation of\ud
bismuth nanopowders by thermal decomposition of\ud
bismuth dodecyl-mercaptide Bi(SC12H25)3 and preliminary\ud
results on their thermoelectric properties are\ud
reported. The thermolysis process leads to Bi nanoparticles\ud
due to the efficient capping agent effect of\ud
the dodecyl-disulfide by-product, which strongly\ud
bonds the surface of the Bi clusters, preventing their\ud
aggregation and significantly reducing their growth\ud
rate. The structure and morphology of the thermolysis\ud
products were investigated by differential scanning\ud
calorimetry, thermogravimetry, X-ray diffractometry,\ud
1H nuclear magnetic resonance spectroscopy, scanning\ud
electron microscopy, and energy dispersive\ud
spectroscopy. It has been shown that the prepared\ud
Bi nanopowder consists of spherical shape nanoparticles,\ud
with the average diameter depending on the\ud
thermolysis temperature. The first results on the\ud
thermoelectric characterization of the prepared Bi\ud
nanopowders reveal a peculiar behavior characterized\ud
by a semimetal–semiconductor transition, and a\ud
significant increase in the Seebeck coefficient when\ud
compared to bulk Bi in the case of the lowest grain\ud
size (170 nm)
Electric vehicles (EVs) are characterized by a significant variety of possible powertrain configurations, ranging from one to four electric machines, which can have an on-board or in-wheel layout. Multiple models of production EVs have recently been introduced on the market, with 4-wheel-drive (4WD) architectures based on a central motor within each axle, connected to the wheels through a gearbox, a differential, and half-shafts. In parallel, an important body of research and industrial demonstrations have covered the topic of 2-speed transmission systems for EVs, with the target of enhancing longitudinal acceleration and gradeability performance, while increasing the operating efficiency of the electric powertrain. Although several recent studies compare different electric powertrain architectures, to the best of the authors’ knowledge the literature misses a comparison between 2-wheel-drive (2WD) and 4WD configurations for the same EV, from the viewpoint of drivability and energy consumption. This paper targets this gap, by assessing 2WD and 4WD powertrain layouts with central motors, for a case study light passenger car for urban mobility, including consideration of the effect of single- and 2-speed transmission systems. An optimization routine is used to calculate the energy-efficient gear state and/or torque distribution for each considered configuration. For the specific EV, the results highlight the favourable trade-off of the single-speed 4WD layout, capable of reducing the energy consumption during driving cycles by approximately 9% with respect to the conventional 2WD layout with single-speed transmission, while providing satisfactory drivability and good gradeability, especially in low tire–road friction conditions.
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