5,316 research outputs found
User evaluation of an interactive learning framework for single-arm and dual-arm robots
The final publication is available at link.springer.comSocial robots are expected to adapt to their users and, like their human counterparts, learn from the interaction. In our previous work, we proposed an interactive learning framework that enables a user to intervene and modify a segment of the robot arm trajectory. The framework uses gesture teleoperation and reinforcement learning to learn new motions. In the current work, we compared the user experience with the proposed framework implemented on the single-arm and dual-arm Barrett’s 7-DOF WAM robots equipped with a Microsoft Kinect camera for user tracking and gesture recognition. User performance and workload were measured in a series of trials with two groups of 6 participants using two robot settings in different order for counterbalancing. The experimental results showed that, for the same task, users required less time and produced shorter robot trajectories with the single-arm robot than with the dual-arm robot. The results also showed that the users who performed the task with the single-arm robot first experienced considerably less workload in performing the task with the dual-arm robot while achieving a higher task success rate in a shorter time.Peer ReviewedPostprint (author's final draft
Two Galaxy Clusters: A3565 and A3560
We report 102 new redshifts and magnitudes for a sample of galaxies to RF ~
15.5 mag in a 2.17 deg x 2.17 deg region centered on the galaxy IC 4296, the
most luminous member of the A3565 cluster. Up to the limiting magnitude we find
29 cluster members, and measure a velocity dispersion of 228 km/s. The
estimated total mass for this system is ~ 3.0 x h**-1 10**13 Msun (where h =
H0/100 km/s/Mpc), and its dynamical properties are quite typical of poor
clusters presenting X-ray emission. We also find that galaxies with absorption
lines are more concentrated towards the center of the cluster, while systems
with emission lines are mainly located in the outer parts. The small velocity
dispersion of the cluster, coupled to the known presence of an interacting pair
of galaxies, and the large extent of the brightest cluster galaxy, could
indicate that galaxy formation through mergers may still be underway in this
system. The surveyed region also contains galaxies belonging to the Shapley
Concentration cluster A3560. Within 30 arc min of the cluster center, we detect
32 galaxies, for which we measure a velocity dispersion of 588 km/s and a mass
of ~2 x h**-1 10**14 Msun. However, because our sample is restricted to
galaxies brighter than M*, these values should be considered only as rough
estimates.Comment: 33 pages, including 6 tables and 9 postscript figures. Uses AAS Latex
macros. Postscript file and ASCII versions of Tables 4 and 6 are available at
http://www.dan.on.br/other_surveys/a3565.html. Scheduled for September 1999
issue of The Astronomical Journa
High resolution measurements of the switching current in a Josephson tunnel junction: Thermal activation and macroscopic quantum tunneling
We have developed a scheme for a high resolution measurement of the switching
current distribution of a current biased Josephson tunnel junction using a
timing technique. The measurement setup is implemented such that the digital
control and read-out electronics are optically decoupled from the analog bias
electronics attached to the sample. We have successfully used this technique to
measure the thermal activation and the macroscopic quantum tunneling of the
phase in a small Josephson tunnel junction with a high experimental resolution.
This technique may be employed to characterize current-biased Josephson tunnel
junctions for applications in quantum information processing.Comment: 10 pages, 8 figures, 1 tabl
1,2,4-Trimethoxydibenzo[b,d]furan-3-ol
The title compound, C15H14O5, is a natural product, isolated from Sorbus lanata Syn. Pyrus lanata (D. Don) found in Pakistan. The compound is composed of three spiro-fused rings. The dihedral angle between the mean planes of the benzene rings is 4.81 (13)°. The methoxy groups are oriented at dihedral angles of 74.44 (14), 83.0 (2) and 66.3 (2)° with respect to the planes of the benzene rings to which they are attached. The molecule is consolidated by three intramolecular O—H⋯O and C—H⋯O hydrogen bonds. In the crystal, molecules are linked by intermolecular O—H⋯O hydrogen bonds, forming infinite chains along the b axis
Feed Planning - Methods Used by “Expert” Farmers
Although formal feed planning has been heavily promoted in New Zealand, relatively few farmers have adopted this approach (Nuthall & Bishop-Hurley, 1999). Reasons for non-adoption have been identified, but little is known about how farmers manage their pastoral farms in the absence of formal feed planning. To this end, the feed management processes used by three successful (expert) farmers were investigated
Performances and stability of a 2.4 ton Gd organic liquid scintillator target for antineutrino detection
In this work we report the performances and the chemical and physical
properties of a (2 x 1.2) ton organic liquid scintillator target doped with Gd
up to ~0.1%, and the results of a 2 year long stability survey. In particular
we have monitored the amount of both Gd and primary fluor actually in solution,
the optical and fluorescent properties of the Gd-doped liquid scintillator
(GdLS) and its performances as a neutron detector, namely neutron capture
efficiency and average capture time. The experimental survey is ongoing, the
target being continuously monitored. After two years from the doping time the
performances of the Gd-doped liquid scintillator do not show any hint of
degradation and instability; this conclusion comes both from the laboratory
measurements and from the "in-tank" measurements. This is the largest stable
Gd-doped organic liquid scintillator target ever produced and continuously
operated for a long period
Red Galaxy Growth and the Halo Occupation Distribution
We have traced the past 7 Gyr of red galaxy stellar mass growth within dark
matter halos. We have determined the halo occupation distribution, which
describes how galaxies reside within dark matter halos, using the observed
luminosity function and clustering of 40,696 0.2<z<1.0 red galaxies in Bootes.
Half of 10^{11.9} Msun/h halos host a red central galaxy, and this fraction
increases with increasing halo mass. We do not observe any evolution of the
relationship between red galaxy stellar mass and host halo mass, although we
expect both galaxy stellar masses and halo masses to evolve over cosmic time.
We find that the stellar mass contained within the red population has doubled
since z=1, with the stellar mass within red satellite galaxies tripling over
this redshift range. In cluster mass halos most of the stellar mass resides
within satellite galaxies and the intra-cluster light, with a minority of the
stellar mass residing within central galaxies. The stellar masses of the most
luminous red central galaxies are proportional to halo mass to the power of a
third. We thus conclude that halo mergers do not always lead to rapid growth of
central galaxies. While very massive halos often double in mass over the past 7
Gyr, the stellar masses of their central galaxies typically grow by only 30%.Comment: Accepted for publication in the ApJ. 34 pages, 22 Figures, 5 Table
The system parameters of DW Ursae Majoris
We present new constraints on the system parameters of the SW Sextantis star
DW Ursae Majoris, based on ultraviolet (UV) eclipse observations with the
Hubble Space Telescope. Our data were obtained during a low state of the
system, in which the UV light was dominated by the hot white dwarf (WD)
primary. Eclipse analysis, using the full Roche lobe geometry, allows us to set
firm limits on the masses and radii of the system components and the distance
between them: 0.67 \leq M_1/M_sun \leq 1.06, 0.008 \leq R_1/R_sun \leq 0.014,
M_2/M_sun > 0.16, R_2/R_sun > 0.28 and a/R_sun > 1.05. For q = M_2/M_1 < 1.5
the inclination must satisfy i > 71 degrees. Using Smith & Dhillon's
mass-period relation for CV secondaries, our estimates for the system
parameters become M_1/M_sun = 0.77 \pm 0.07, R_1/R_sun = 0.012 \pm 0.001,
M_2/M_sun = 0.30 \pm 0.10, R_2/R_sun = 0.34 \pm 0.04, q =0.39 \pm 0.12, i = 82
\pm 4 degrees and a/R_sun = 1.14 \pm 0.06. We have also estimated the spectral
type of the secondary, M3.5 \pm 1.0, and distance to the system, d =930 \pm 160
pc, from time-resolved I- and K-band photometry. Finally, we have repeated
Knigge et al.'s WD model atmosphere fit to the low-state UV spectrum of DW UMa
in order to account for the higher surface gravity indicated by our eclipse
analysis. In this way we obtained a second estimate for the distance, d = 590
\pm 100 pc, which allows us to obtain a second estimate for the spectral type
of the secondary, M7 \pm 2.0. We conclude that the true value for the distance
and spectral type will probably be in between the values obtained by the two
methods.Comment: 23 pages including 5 figures and 3 tables. Accepted for publication
in Ap
Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift
International audienceContinental rift systems form by propagation of isolated rift segments that interact, and eventually evolve into continuous zones of deformation. This process impacts many aspects of rifting including rift morphology at breakup, and eventual ocean-ridge segmentation. Yet, rift segment growth and interaction remain enigmatic. Here we present geological data from the poorly documented Ririba rift (South Ethiopia) that reveals how two major sectors of the East African rift, the Kenyan and Ethiopian rifts, interact. We show that the Ririba rift formed from the southward propagation of the Ethiopian rift during the Pliocene but this propagation was short-lived and aborted close to the Pliocene-Pleistocene boundary. Seismicity data support the abandonment of laterally offset, overlapping tips of the Ethiopian and Kenyan rifts. Integration with new numerical models indicates that rift abandonment resulted from progressive focusing of the tectonic and magmatic activity into an oblique, throughgoing rift zone of near pure extension directly connecting the rift sectors
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