183 research outputs found
The variable step size regularized block exact affine projection algorithm
No full textThis paper presents several block exact affine projection algorithms (BEAPA) with a variable regularization factor and/or variable step size. The performance of the algorithms is investigated for the acoustic echo cancellation (AEC) and noise reduction applications. It is shown that the variable step size regularized BEAPA whose regularization factor and variable step size are adjusted according to the square of a time-averaging estimate of the autocorrelation of a priori and a posteriori errors is a possible choice for AEC and noise reduction systems. © 2012 IEEE
Intrinsically Elastic Robots: the Key to Human Like Performance
No full textIntrinsically elastic robots, which technically implement some key characteristics of the human muskoskeletal system, have become a major research topic in nowadays robotics. These novel devices open up entirely new control approaches. They base on temporary storage of potential energy and its timed transformation into kinetic energy. In legged locomotion, such considerations have been a common tool for unveiling the respective fundamental physical processes. However, in arm control, elasticities were typically considered parasitic. In this video we outline our efforts in exploiting the inherent capabilities of intrinsically elastic robots in order to bring them closer to human performance. Instead of applying
purely kinematic learing-by-demonstration approaches, which are certainly suboptimal, we argue for using model based techniques in order to optimally exploit the system dynamics such that highly dynamic motion and manipulation capabilities can be achieved. In particular, the explicit use of elasticities as temporary energy tanks can be fully exploited, if they are modeled adequately as an integral part of the mechanism. We
also believe that such approaches can substantially contribute to the understanding of human motion biomechanics
First Analysis and Experiments in Aerial Manipulation Using fully Actuated Redundant Robot Arm.
No full textDifferential Hebbian learning with time-continuous signals for active noise reduction
No full textSpike timing-dependent plasticity, related to differential Hebb-rules, has become a leading paradigm in neuronal learning, because weights can grow or shrink depending on the timing of pre- and post-synaptic signals. Here we use this paradigm to reduce unwanted (acoustic) noise. Our system relies on heterosynaptic differential Hebbian learning and we show that it can efficiently eliminate noise by up to -140 dB in multi-microphone setups under various conditions. The system quickly learns, most often within a few seconds, and it is robust with respect to different geometrical microphone configurations, too. Hence, this theoretical study demonstrates that it is possible to successfully transfer differential Hebbian learning, derived from the neurosciences, into a technical domain
Lattice-Isomorphic Groups, and Infinite Abelian <i>g</I>-cogalois Field Extensions
No full textThe aim of this paper is to provide a proof of the following result claimed by Albu (Infinite field extensions with Galois-Cogalois correspondence (II), Revue Roumaine Math. Pures Appl. 47 (2002), to appear): The Kneser group Kne(E/F) of an Abelian G-Cogalois extension E/F and the group of continuous characters Ch(Gal(E/F)) of its Galois group Gal(E/F) are isomorphic (in a noncanonical way). The proof we give in this paper explains why such an isomorphism is expected, being based on a classical result of Baer (Amer. J. Math. 61 (1939), 1-44) devoted to the existence of group isomorphisms arising from lattice isomorphisms of their lattices of subgroups.Alexander von Humboldt Foundation; Consiliul National al Cercetarii Stiintifice din Invatamantul Superior, Romania; grant of Romanian AcademyThis work was completed during the stay of the first author at the Heinrich-Heine University of Dusseldorf as a Humboldt Fellow in April-June 2001. He is very indebted to the University for hospitality and to the Alexander von Humboldt Foundation for financial support. He gratefully acknowledges partial support from grant D-7 awarded by the Consiliul National al Cercetarii Stiintifice din Invatamantul Superior, Romania. He would also like to thank Mihai Sabac for helpful discussions on characters of locally compact Abelian groups.r The second author gratefully acknowledges partial support from a grant of the Romanian Academy
Chenopodium album (Lamb's-quarters) : Lamb's-quarters
No full textClass: Dicotyledoneae
Family: Chenopodiaceae
Genus: Chenopodium
Species: albu
Amaranthus albus (Tumble weed) : Tumble weed
No full textClass: Dicotyledoneae
Family: Amaranthaceae
Genus: Amaranthus
Species: albu
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