260,464 research outputs found
Radio observations of two intermittent pulsars: PSRs J1832+0029 and J1841-0500
We present long-term observations of two intermittent pulsars,
PSRs~J1832+0029 and J18410500 using the Parkes 64\,m radio telescope. The
radio emission for these pulsars switches "off" for year-long durations. Our
new observations have enabled us to improve the determination of the on-off
timescales and the spin down rates during those emission states. In general our
results agree with previous studies of these pulsars, but we now have
significantly longer data spans. We have identified two unexpected signatures
in the data. Weak emission was detected in a single observation of
PSR~J18320029 during an "off" emission state. For PSR~J18410500, we
identified a quasi-periodic fluctuation in the intensities of the detectable
single pulses, with a modulation period between 21 and 36 pulse periods.Comment: 7 pages, 7 figures, accepted for publication in Ap
Precise computer controlled positioning of robot end effectors using force sensors
A thorough study of combined position/force control using sensory feedback for a one-dimensional manipulator model, which may count for the spacecraft docking problem or be extended to the multi-joint robot manipulator problem, was performed. The additional degree of freedom introduced by the compliant force sensor is included in the system dynamics in the design of precise position control. State feedback based on the pole placement method and with integral control is used to design the position controller. A simple constant gain force controller is used as an example to illustrate the dependence of the stability and steady-state accuracy of the overall position/force control upon the design of the inner position controller. Supportive simulation results are also provided
Double-peaked Narrow Emission-line Galaxies in LAMOST Survey
We outline a full-scale search for galaxies exhibiting double-peaked profiles
of promi- nent narrow emission lines, motivated by the prospect of finding
objects related to merging galaxies, and even dual active galactic nuclei
candidates as by-product, from the Large Sky Area Multi-object Fiber
Spectroscopic Telescope (LAMOST) Data Re- lease 4. We assemble a large sample
of 325 candidates with double-peaked or strong asymmetric narrow emission
lines, with 33 objects therein appearing optically resolved dual-cored
structures, close companions or signs of recent interaction on the Sloan Dig-
ital Sky Survey images. A candidate from LAMOST (J074810.95+281349.2) is also
stressed here based on the kinematic and spatial decompositions of the
double-peaked narrow emission line target, with analysis from the
cross-referenced Mapping Nearby Galaxies at the Apache Point Observatory
(MaNGA) survey datacube. MaNGA en- ables us to constrain the origin of double
peaks for these sources, and with the IFU data we infer that the most promising
origin of double-peaked profiles for LAMOST J074810.95+281349.2 is the
`Rotation Dominated + Disturbance' structure.Comment: 13 pages, 9 figures, accepted by MNRA
- …