9,304 research outputs found
Fuzzy logic control for energy saving in autonomous electric vehicles
Limited battery capacity and excessive battery dimensions have been two major limiting factors in the rapid advancement of electric vehicles. An alternative to increasing battery capacities is to use better: intelligent control techniques which save energy on-board while preserving the performance that will extend the range with the same or even smaller battery capacity and dimensions. In this paper, we present a Type-2 Fuzzy Logic Controller (Type-2 FLC) as the speed controller, acting as the Driver Model Controller (DMC) in Autonomous Electric Vehicles (AEV). The DMC is implemented using realtime control hardware and tested on a scaled down version of a back to back connected brushless DC motor setup where the actual vehicle dynamics are modelled with a Hardware-In-the-Loop (HIL) system. Using the minimization of the Integral Absolute Error (IAE) has been the control design criteria and the performance is compared against Type-1 Fuzzy Logic and Proportional Integral Derivative DMCs. Particle swarm optimization is used in the control design. Comparisons on energy consumption and maximum power demand have been carried out using HIL system for NEDC and ARTEMIS drive cycles. Experimental results show that Type-2 FLC saves energy by a substantial amount while simultaneously achieving the best IAE of the control strategies tested
Metallicity of the polar disk in NGC4650A: constraints for cold accretion scenario
We used high resolution spectra in the optical and near-infrared wavelength
range to study the abundance ratios and metallicities of the HII regions
associated with the polar disk in NGC4650A, in order to put constraints on the
formation of the polar disk through cold gas accretion along a filament; this
might be the most realistic way by which galaxies get their gas. We have
compared the measured metallicities for the polar structure in NGC4650A with
those of different morphological types and we have found that they are similar
to those of late-type galaxies: such results is consistent with a polar disk
formed by accretion from cosmic web filaments of external cold gas.Comment: Proceeding of the conference "Hunting for the Dark: The Hidden Side
of Galaxy Formation", Malta, 19-23 Oct. 200
Interpretable timbre synthesis using variational autoencoders regularized on timbre descriptors
Controllable timbre synthesis has been a subject of research for several decades, and deep neural networks have been the most successful in this area. Deep generative models such as Variational Autoencoders (VAEs) have the ability to generate a high-level representation of audio while providing a structured latent space. Despite their advantages, the interpretability of these latent spaces in terms of human perception is often limited. To address this limitation and enhance the control over timbre generation, we propose a regularized VAE-based latent space that incorporates timbre descriptors. Moreover, we suggest a more concise representation of sound by utilizing its harmonic content, in order to minimize the dimensionality of the latent space
The Metal-Insulator Transition of NbO2: an Embedded Peierls Instability
Results of first principles augmented spherical wave electronic structure
calculations for niobium dioxide are presented. Both metallic rutile and
insulating low-temperature NbO2, which crystallizes in a distorted rutile
structure, are correctly described within density functional theory and the
local density approximation. Metallic conductivity is carried to equal amounts
by metal t_{2g} orbitals, which fall into the one-dimensional d_parallel band
and the isotropically dispersing e_{g}^{pi} bands. Hybridization of both types
of bands is almost negligible outside narrow rods along the line X--R. In the
low-temperature phase splitting of the d_parallel band due to metal-metal
dimerization as well as upshift of the e_{g}^{pi} bands due to increased p-d
overlap remove the Fermi surface and open an optical band gap of about 0.1 eV.
The metal-insulator transition arises as a Peierls instability of the
d_parallel band in an embedding background of e_{g}^{pi} electrons. This basic
mechanism should also apply to VO2, where, however, electronic correlations are
expected to play a greater role due to stronger localization of the 3d
electrons.Comment: 4 pages, revtex, 6 eps figures, additional material avalable at
http://www.physik.uni-augsburg.de/~eyert
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