3,943 research outputs found
The 3D model control of image processing
Telerobotics studies remote control of distant robots by a human operator using supervisory or direct control. Even if the robot manipulators has vision or other senses, problems arise involving control, communications, and delay. The communication delays that may be expected with telerobots working in space stations while being controlled from an Earth lab have led to a number of experiments attempting to circumvent the problem. This delay in communication is a main motivating factor in moving from well understood instantaneous hands-on manual control to less well understood supervisory control; the ultimate step would be the realization of a fully autonomous robot. The 3-D model control plays a crucial role in resolving many conflicting image processing problems that are inherent in resolving in the bottom-up approach of most current machine vision processes. The 3-D model control approach is also capable of providing the necessary visual feedback information for both the control algorithms and for the human operator
Doppler-Induced Dynamics of Fields in Fabry-Perot Cavities with Suspended Mirrors
The Doppler effect in Fabry-Perot cavities with suspended mirrors is
analyzed. Intrinsically small, the Doppler shift accumulates in the cavity and
becomes comparable to or greater than the line-width of the cavity if its
finesse is high or its length is large. As a result, damped oscillations of the
cavity field occur when one of the mirrors passes a resonance position. A
formula for this transient is derived. It is shown that the frequency of the
oscillations is equal to the accumulated Doppler shift and the relaxation time
of the oscillations is equal to the storage time of the cavity. Comparison of
the predicted and the measured Doppler shift is discussed, and application of
the analytical solution for measurement of the mirror velocity is described
Instrumentation and robotic image processing using top-down model control
A top-down image processing scheme is described. A three-dimensional model of a robotic working environment, with robot manipulators, workpieces, cameras, and on-the-scene visual enhancements is employed to control and direct the image processing, so that rapid, robust algorithms act in an efficient manner to continually update the model. Only the model parameters are communicated, so that savings in bandwidth are achieved. This image compression by modeling is especially important for control of space telerobotics. The background for this scheme lies in an hypothesis of human vision put forward by the senior author and colleagues almost 20 years ago - the Scanpath Theory. Evidence was obtained that repetitive sequences of saccadic eye movements, the scanpath, acted as the checking phase of visual pattern recognition. Further evidence was obtained that the scanpaths were apparently generated by a cognitive model and not directly by the visual image. This top-down theory of human vision was generalized in some sense to the frame in artificial intelligence. Another source of the concept arose from bioengineering instrumentation for measuring the pupil and eye movements with infrared video cameras and special-purpose hardware
The Use of Song to Open an Educational Development Workshop: Exploratory Analysis and Reflections
Song has been used by faculty of many disciplines in their classrooms and, to a lesser extent, by educational developers in workshops. This paper shares and discusses a new song (about an instructor’s evolving openness to alternatives to lecture only teaching) and its novel use to open an educational development workshop. Self reported participant data from an exploratory survey suggest that the song was most effective in reducing stress as well as in increasing motivation, morale, engagement, and connection. Practical implications and implementation considerations are discussed regarding the song as well as related creative work
A family of representations of braid groups on surfaces
We propose a family of new representations of the braid groups on surfaces
that extend linear representations of the braid groups on a disc such as the
Burau representation and the Lawrence-Krammer-Bigelow representation.Comment: 21 pages, 4 figure
Subgenual Cingulum Microstructure Supports Control of Emotional Conflict
This is the final version of the article. Available from Oxford University Press via the DOI in this record.Major depressive disorder (MDD) is associated with specific difficulties in attentional disengagement from negatively valenced material. Diffusion MRI studies have demonstrated altered white matter microstructure in the subgenual cingulum bundle (CB) in individuals with MDD, though the functional significance of these alterations has not been examined formally. This study explored whether individual differences in selective attention to negatively valenced stimuli are related to interindividual differences in subgenual CB microstructure. Forty-six individuals (21 with remitted MDD, 25 never depressed) completed an emotional Stroop task, using happy and angry distractor faces overlaid by pleasant or unpleasant target words and a control gender-based Stroop task. CBs were reconstructed in 38 individuals using diffusion-weighted imaging and tractography, and mean fractional anisotropy (FA) computed for the subgenual, retrosplenial, and parahippocampal subdivisions. No significant correlations were found between FA and performance in the control gender-based Stroop task in any CB region. However, the degree of interference produced by angry face distractors on time to identify pleasant words (emotional conflict) correlated selectively with FA in the subgenual CB (r= -0.53;P= 0.01). Higher FA was associated with reduced interference, irrespective of a diagnosis of MDD, suggesting that subgenual CB microstructure is functionally relevant for regulating attentional bias toward negative interpersonal stimuli.P.A.K. was funded by the Higher Education Funding Council for Wales (HEFCW) and an Academy of Medical Sciences and Wellcome Trust Starter Grant (AJ17102004). M.M. received an EPSRC Doctoral Training Grant. This work was also supported by a Marie Curie fellowship to Marcel Meyer and received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 267171. D.K.J. was funded by HEFCW and received grants from the MS Society, a Wellcome Trust New Investigator Award, a Wellcome Trust Multi User Equipment Grant and Medical Research Council, and Wellcome Trust project grants. A.N.D. was supported by the Wellcome Trust PhD schemes. N.L. was funded by HEFCW. A.D.L. was funded by HEFCW. He also received grants from the ESRC, Wellcome Trust, and NISCHR. Funding to pay the Open Access publication charges for this article was provided by The Wellcome Trust
Fundamental Limits of Multiple-Access Integrated Sensing and Communication Systems
A memoryless state-dependent multiple access channel is considered to model
an integrated sensing and communication system, where two transmitters wish to
convey messages to a receiver while simultaneously estimating the sensing state
sequences through echo signals. In particular, the sensing states are assumed
to be correlated with the channel state, and the receiver has imperfect channel
state information. In this setup, improved inner and outer bounds for
capacity-distortion region are derived. The inner bound is based on an
achievable scheme that combines message cooperation and joint compression via
distributed Wyner-Ziv coding at each transmitter, resulting in unified
cooperative communication and sensing. The outer bound is based on the ideas of
dependence balance for communication rate and rate-limited constraints on
sensing distortion. The proposed inner and outer bounds are proved to improve
the state-of-the-art bounds. Finally, numerical examples are provided to
demonstrate that our new inner and outer bounds strictly improve the existing
results
Spectral classification of Pleiades brown dwarf candidates
We report on the results of the spectroscopy of 10 objects previously
classified as brown dwarf candidates via RIJHK colors by Eisenbeiss et al.
(2009), who performed deep imaging observations on a 0.4 sq.deg. field at the
edge of the Pleiades. We describe and judge on classification techniques in the
region of M-type stars. To classify and characterise the objects, visual and
near infrared spectra have been obtained with VLT FORS and ISAAC. The spectral
classification was performed using the shape of the spectra as well as spectral
indices that are sensitive to the spectral type and luminosity class of Mtype
stars and late M-type brown dwarfs. Furthermore a spectrophotometric distance
was calculated and compared the distance of the Pleiades to investigate the
membership probability. As a second argument we analyzed the proper motion. The
brown dwarf candidates were found not to be brown dwarfs, but late-K to
mid-M-type dwarf stars. Based on the obtained distance and tabulated proper
motions we conclude that all objects are background dwarf stars.Comment: 10 pages, 5 figure
Centennial- to decadal-scale monsoon precipitation variations in the upper Hanjiang River region, China over the past 6650 years
The upper Hanjiang River region is the recharge area of the middle route of South-to-North Water Transfer Project. The region is under construction of the Hanjiang-Weihe River Water Transfer Project in China. Monsoon precipitation variations in this region are critical to water resource and security of China. In this study, high-resolution monsoon precipitation variations were reconstructed in the upper Hanjiang River region over the past 6650 years from delta O-18 and delta C-13 records of four stalagmites in Xianglong cave. The long term increasing trend of stalagmite delta O-18 record since the middle Holocene is consistent with other speleothem records from monsoonal China. This trend follows the gradually decreasing Northern Hemisphere summer insolation, which indicates that solar insolation may control the orbital-scale East Asian summer monsoon (EASM) variations. Despite the declined EASM intensity since the middle Holocene, local precipitation may not have decreased remarkably, as revealed by the delta C-13 records. A series of centennial- to decadal-scale cyclicity was observed, with quasi-millennium-, quasi-century-, 57-, 36- and 22-year cycles by removing the long-term trend of stalagmite delta O-18 record. Increased monsoon precipitation during periods of 4390-3800 a BP, 3590-2960 a BP, 2050-1670 a BP and 1110-790 a BP had caused four super-floods in the upper reach of Hanjiang River. Dramatically dry climate existed in this region during the 5.0 ka and 2.8 ka events, coinciding with notable droughts in other regions of monsoonal China. Remarkably intensified and southward Westerly jet, together with weakened summer monsoon, may delay the onset of rainy seasons, resulting in synchronous decreasing of monsoon precipitation in China during the two events. During the 4.2 ka event and the Little Ice Age, the upper Hanjiang River region was wet, which was similar to the climate conditions in central and southern China, but was the opposite of drought observed in northern China. We propose that weakened summer monsoon and less strengthened or normal Westerly jet may cause rain belt stay longer in the southward region, which reduced rainfall in northern China but enhanced it in central and southern China. (C) 2017 Elsevier B.V. All rights reserved
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