2,226 research outputs found
Summary report: A preliminary investigation into the use of fuzzy logic for the control of redundant manipulators
The Rice University Department of Mechanical Engineering and Materials Sciences' Robotics Group designed and built an eight degree of freedom redundant manipulator. Fuzzy logic was proposed as a control scheme for tasks not directly controlled by a human operator. In preliminary work, fuzzy logic control was implemented for a camera tracking system and a six degree of freedom manipulator. Both preliminary systems use real time vision data as input to fuzzy controllers. Related projects include integration of tactile sensing and fuzzy control of a redundant snake-like arm that is under construction
A multi-sensor system for robotics proximity operations
Robots without sensors can perform only simple repetitive tasks and cannot cope with unplanned events. A multi-sensor system is needed for a robot to locate a target, move into its neighborhood and perform operations in contact with the object. Systems that can be used for such tasks are described
Multiple cyclotron line-forming regions in GX 301-2
We present two observations of the high-mass X-ray binary GX 301-2 with
NuSTAR, taken at different orbital phases and different luminosities. We find
that the continuum is well described by typical phenomenological models, like a
very strongly absorbed NPEX model. However, for a statistically acceptable
description of the hard X-ray spectrum we require two cyclotron resonant
scattering features (CRSF), one at ~35 keV and the other at ~50 keV. Even
though both features strongly overlap, the good resolution and sensitivity of
NuSTAR allows us to disentangle them at >=99.9% significance. This is the first
time that two CRSFs are seen in GX 301-2. We find that the CRSFs are very
likely independently formed, as their energies are not harmonically related
and, if it were a single line, the deviation from a Gaussian shape would be
very large. We compare our results to archival Suzaku data and find that our
model also provides a good fit to those data. We study the behavior of the
continuum as well as the CRSF parameters as function of pulse phase in seven
phase bins. We find that the energy of the 35 keV CRSF varies smoothly as
function of phase, between 30-38 keV. To explain this variation, we apply a
simple model of the accretion column, taking the altitude of the line-forming
region, the velocity of the in-falling material, and the resulting relativistic
effects into account. We find that in this model the observed energy variation
can be explained simply due to a variation of the projected velocity and
beaming factor of the line forming region towards us.Comment: 18 pages, 10 figures, accepted for publication in A&
Book Reviews
The Law Practice of Alexander Hamilton By Julius Goebel, Ed. and Associate Editors New York and London: Columbia University Press, 1964. Pp. XXV, 898.
reviewer: Elliot E. Cheatham
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Lawyers in Politics: A Study in Professional Convergence By Heinz Eulau and John D. Sprague Indianapolis: Bobbs-Merrill,1964. Pp. 164. $1.95.
reviewer: Joseph B. Board, Jr.
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Occupational Disability and Public Policy Edited by Earl F. Cheit and Margaret S. Gordon. New York: John Wiley and Sons,Inc., 1963. Pp. xii, 446.
reviewer: Monroe Berkowit
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Mass casualty events: what to do as the dust settles?
Care during mass casualty events (MCE) has improved during the last 15 years. Military and civilian collaboration has led to partnerships which augment the response to MCE. Much has been written about strategies to deliver care during an MCE, but there is little about how to transition back to normal operations after an event. A panel discussion entitled The Day(s) After: Lessons Learned from Trauma Team Management in the Aftermath of an Unexpected Mass Casualty Event at the 76th Annual American Association for the Surgery of Trauma meeting on September 13, 2017 brought together a cadre of military and civilian surgeons with experience in MCEs. The events described were the First Battle of Mogadishu (1993), the Second Battle of Fallujah (2004), the Bagram Detention Center Rocket Attack (2014), the Boston Marathon Bombing (2013), the Asiana Flight 214 Plane Crash (2013), the Baltimore Riots (2015), and the Orlando Pulse Night Club Shooting (2016). This article focuses on the lessons learned from military and civilian surgeons in the days after MCEs
Spectral and Timing Analysis of the accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR
We present an analysis of the spectral shape and pulse profile of the
accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR during a
spin-up state. The pulsar, which experienced a torque reversal to spin-up in
2008, has a spin period of 7.7 s. Comparing the phase-averaged spectra obtained
with Suzaku in 2010 and with NuSTAR in 2015, we find that the spectral shape
changed between the two observations: the 3-10 keV flux increased by 5% while
the 30-60 keV flux decreased significantly by 35%. Phase-averaged and
phase-resolved spectral analysis shows that the continuum spectrum observed by
NuSTAR is well described by an empirical NPEX continuum with an added broad
Gaussian emission component around the spectral peak at 20 keV. Taken together
with the observed Pdot value obtained from Fermi/GBM, we conclude that the
spectral change between the Suzaku and NuSTAR observations was likely caused by
an increase of the accretion rate. We also report the possible detection of
asymmetry in the profile of the fundamental cyclotron line. Furthermore, we
present a study of the energy-resolved pulse profiles using a new relativistic
ray tracing code, where we perform a simultaneous fit to the pulse profiles
assuming a two-column geometry with a mixed pencil- and fan-beam emission
pattern. The resulting pulse profile decompositions enable us to obtain
geometrical parameters of accretion columns (inclination, azimuthal and polar
angles) and a fiducial set of beam patterns. This information is important to
validate the theoretical predictions from radiation transfer in a strong
magnetic field.Comment: 19 pages, 14 figures, Accepted for publication in ApJ on May 5, 201
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