8,752 research outputs found
Diagonal Riccati Stability and Applications
We consider the question of diagonal Riccati stability for a pair of real
matrices A, B. A necessary and sufficient condition for diagonal Riccati
stability is derived and applications of this to two distinct cases are
presented. We also describe some motivations for this question arising in the
theory of generalised Lotka-Volterra systems
Representations of the Symmetric Group and Nonstandard Quantum Statistics
From the Washington University Senior Honors Thesis Abstracts (WUSHTA), Spring 2018. Published by the Office of Undergraduate Research. Joy Zalis Kiefer, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Lindsey Paunovich, Editor; Helen Human, Programs Manager and Assistant Dean in the College of Arts and Sciences Mentor: Renato Fere
Momentum Control with Hierarchical Inverse Dynamics on a Torque-Controlled Humanoid
Hierarchical inverse dynamics based on cascades of quadratic programs have
been proposed for the control of legged robots. They have important benefits
but to the best of our knowledge have never been implemented on a torque
controlled humanoid where model inaccuracies, sensor noise and real-time
computation requirements can be problematic. Using a reformulation of existing
algorithms, we propose a simplification of the problem that allows to achieve
real-time control. Momentum-based control is integrated in the task hierarchy
and a LQR design approach is used to compute the desired associated closed-loop
behavior and improve performance. Extensive experiments on various balancing
and tracking tasks show very robust performance in the face of unknown
disturbances, even when the humanoid is standing on one foot. Our results
demonstrate that hierarchical inverse dynamics together with momentum control
can be efficiently used for feedback control under real robot conditions.Comment: 21 pages, 11 figures, 4 tables in Autonomous Robots (2015
Motion of a vortex line near the boundary of a semi-infinite uniform condensate
We consider the motion of a vortex in an asymptotically homogeneous
condensate bounded by a solid wall where the wave function of the condensate
vanishes. For a vortex parallel to the wall, the motion is essentially
equivalent to that generated by an image vortex, but the depleted surface layer
induces an effective shift in the position of the image compared to the case of
a vortex pair in an otherwise uniform flow. Specifically, the velocity of the
vortex can be approximated by ,
where is the distance from the center of the vortex to the wall, is
the healing length of the condensate and is the mass of the boson.Comment: submitted to Phys Rev
Development Strategies for Animal Medical Therapeutics
The process of developing a new therapeutic is long, expensive, and risky. Current small animal models are often poor representations of human disease, contributing to the high rate of failure in human trials. Outbred dogs can be excellent models for researching human disease. Clinical trials in dogs are inexpensive and efficient compared with human trials. Advaxis, a clinical-stage biotechnology company developing cancer immunotherapies, provides one case study on how trials in dogs can help advance trials in humans
X-ray and optical variability of Seyfert 1 galaxies as observed with XMM-Newton
We have examined simultaneous X-ray and optical light curves of a sample of
eight nearby Seyfert 1 galaxies observed using the EPIC X-ray cameras and
Optical Monitor on board XMM. The observations span ~1 day and revealed optical
variability in four of the eight objects studied. In all cases, the X-ray
variability amplitude exceeded that of the optical both in fractional and
absolute luminosity terms. No clearly significant correlations were detected
between wavebands using cross correlation analysis. We conclude that, in three
of the four objects in which optical variability was detected, reprocessing
mechanisms between wavebands do not dominate either the optical or X-ray
variability on the time-scales probed.Comment: 9 pages, 2 figures, accepted for publication in MNRA
EEG Correlates of Consciousness During Sleep: A Pilot Study
The following is an abstract of a pilot study posted in the corollary sessions at the Lucidity Association's Conference on Higher States of Consciousness, in Chicago in July, 1990
Working the crowd : improvisational entrepreneurship and equity crowdfunding in nascent entrepreneurial ventures
Equity crowdfunding has rapidly established itself as an important part of the funding landscape for nascent entrepreneurial ventures. To date, however, little is known about the nature of the demand for equity crowdfunding or its impact on recipient firms. This paper draws on an interview-based study of entrepreneurs in 42 equity crowdfunded start-ups in the UK. The study found strong demand for this funding from these experimental and improvisational entrepreneurs within innovative, consumer-focused, early stage firms. Many entrepreneurs were classic âdiscouraged borrowersâ attracted by the ability to obtain finance quickly with relatively little diminution of their equity or autonomy. In terms of impact, equity crowdfunding seems to confer important intangible benefits to investee companies which amount to more than money. Given their strongly improvisational nature, the concept of entrepreneurial bricolage seems a suitable theoretical lens explicating the behavioural aspects of the entrepreneurs examined.PostprintPeer reviewe
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