9,385 research outputs found
A system for synthetic vision and augmented reality in future flight decks
Rockwell Science Center is investigating novel human-computer interaction techniques for enhancing the situational awareness in future flight decks. One aspect is to provide intuitive displays that provide the vital information and the spatial awareness by augmenting the real world with an overlay of relevant information registered to the real world. Such Augmented Reality (AR) techniques can be employed during bad weather scenarios to permit flying in Visual Flight Rules (VFR) in conditions which would normally require Instrumental Flight Rules (IFR). These systems could easily be implemented on heads-up displays (HUD). The advantage of AR systems vs. purely synthetic vision (SV) systems is that the pilot can relate the information overlay to real objects in the world, whereas SV systems provide a constant virtual view, where inconsistencies can hardly be detected. The development of components for such a system led to a demonstrator implemented on a PC. A camera grabs video images which are overlaid with registered information. Orientation of the camera is obtained from an inclinometer and a magnetometer; position is acquired from GPS. In a possible implementation in an airplane, the on-board attitude information can be used for obtaining correct registration. If visibility is sufficient, computer vision modules can be used to fine-tune the registration by matching visual cues with database features. This technology would be especially useful for landing approaches. The current demonstrator provides a frame-rate of 15 fps, using a live video feed as background with an overlay of avionics symbology in the foreground. In addition, terrain rendering from a 1 arc sec. digital elevation model database can be overlaid to provide synthetic vision in case of limited visibility. For true outdoor testing (on ground level), the system has been implemented on a wearable computer
An extendible software for learning to write Chinese characters in correct stroke sequences on smartphones
With the fast economic development in China, learning to understand Chinese becomes very crucial and popular worldwide. To most foreigners and even native Chinese students, one of the major challenges in learning Chinese is to write Chinese characters in correct stroke sequences since the correct stroke sequences of writing any Chinese character is regarded as crucial in the Chinese culture. Intrinsically, there were very few available character recognition techniques that can tackle the complexity of structures of Chinese characters together with their stroke sequences. In this paper, we propose an extendible and intelligent e-learning software based on learning objects to facilitate the learning of writing Chinese characters in correct stroke sequences. To demonstrate the feasibility of our proposal, a prototype of our proposed e-learning software was built on smartphones. Our proposal represents the first attempt to reduce the complexity while increasing the extendibility of the e-learning software to learn Chinese through learning objects. More importantly, it opens up numerous opportunities for further investigations. © 2011 IEEE.published_or_final_versionThe 11th IEEE International Conference on Advanced Learning Technologies (ICALT 2011), Athens, GA., 6-8 July 2011. In Proceedings of the IEEE International Conference on Advanced Learning Technologies, 2011, p. 118-11
Local Density of the Bose Glass Phase
We study the Bose-Hubbard model in the presence of on-site disorder in the
canonical ensemble and conclude that the local density of the Bose glass phase
behaves differently at incommensurate filling than it does at commensurate one.
Scaling of the superfluid density at incommensurate filling of and
on-site interaction predicts a superfluid-Bose glass transition at
disorder strength of . At this filling the local density
distribution shows skew behavior with increasing disorder strength.
Multifractal analysis also suggests a multifractal behavior resembling that of
the Anderson localization. Percolation analysis points to a phase transition of
percolating non-integer filled sites around the same value of disorder. Our
findings support the scenario of percolating superfluid clusters enhancing
Anderson localization near the superfluid-Bose glass transition. On the other
hand, the behavior of the commensurate filled system is rather different. Close
to the tip of the Mott lobe () we find a Mott insulator-Bose
glass transition at disorder strength of . An analysis of
the local density distribution shows Gaussian like behavior for a wide range of
disorders above and below the transition.Comment: 12 pages, 14 figure
Using cloud computing and mobile devices to facilitate students' learning through e-learning games
The recent advance in cloud computing and mobile devices empowers many innovative e-learning systems or games with increased interactivity and improved features. In this paper, we consider an innovative framework of cloud-based e-learning games that can be assessed through mobile devices to enhance students' learning anytime and anywhere. Being model-based, our proposal is adaptive and highly portable that can be easily customized to any existing cloud platform. Besides, our proposed framework allows course instructors or game designers to flexibly modify any part of an e-learning game, and continuously monitor the performance of individuals who try to compete with each other to attain better results. It is worth noting that this paper reports an on-going work, namely the iGame@Cloud system, for which a thorough evaluation will be conducted later. After all, our proposal stimulates many interesting directions for further exploration. © 2013 IEEE.published_or_final_versio
A Survey of 56 Mid-latitude EGRET Error Boxes for Radio Pulsars
We have conducted a radio pulsar survey of 56 unidentified gamma-ray sources
from the 3rd EGRET catalog which are at intermediate Galactic latitudes (5 deg.
< |b| < 73 deg.). For each source, four interleaved 35-minute pointings were
made with the 13-beam, 1400-MHz multibeam receiver on the Parkes 64-m radio
telescope. This covered the 95% error box of each source at a limiting
sensitivity of about 0.2 mJy to pulsed radio emission for periods P > 10 ms and
dispersion measures < 50 pc cm-3. Roughly half of the unidentified gamma-ray
sources at |b| > 5 deg. with no proposed active galactic nucleus counterpart
were covered in this survey. We detected nine isolated pulsars and four
recycled binary pulsars, with three from each class being new. Timing
observations suggest that only one of the pulsars has a spin-down luminosity
which is even marginally consistent with the inferred luminosity of its
coincident EGRET source. Our results suggest that population models, which
include the Gould belt as a component, overestimate the number of isolated
pulsars among the mid-latitude Galactic gamma-ray sources and that it is
unlikely that Gould belt pulsars make up the majority of these sources.
However, the possibility of steep pulsar radio spectra and the confusion of
terrestrial radio interference with long-period pulsars (P > 200 ms) having
very low dispersion measures (< 10 pc cm-3, expected for sources at a distance
of less than about 1 kpc) prevent us from strongly ruling out this hypothesis.
Our results also do not support the hypothesis that millisecond pulsars make up
the majority of these sources. Non-pulsar source classes should therefore be
further investigated as possible counterparts to the unidentified EGRET sources
at intermediate Galactic latitudes.Comment: 24 pages, including 4 figures and 3 tables. Accepted for publication
in Ap
Chandra Monitoring of the Candidate Anomalous X-ray Pulsar AX J1845.0-0258
The population of clearly identified anomalous X-ray pulsars has recently
grown to seven, however, one candidate anomalous X-ray pulsar (AXP) still
eludes re-confirmation. Here, we present a set of seven Chandra ACIS-S
observations of the transient pulsar AX J1845.0-0258, obtained during 2003. Our
observations reveal a faint X-ray point source within the ASCA error circle of
AX J1845.0-0258's discovery, which we designate CXOU J184454.6-025653 and
tentatively identify as the quiescent AXP. Its spectrum is well described by an
absorbed single-component blackbody (kT~2.0 keV) or power law (Gamma~1.0) that
is steady in flux on timescales of at least months, but fainter than AX
J1845.0-0258 was during its 1993 period of X-ray enhancement by at least a
factor of 13. Compared to the outburst spectrum of AX J1845.0-0258, CXOU
J184454.6-025653 is considerably harder: if truly the counterpart, then its
spectral behaviour is contrary to that seen in the established transient AXP
XTE J1810-197, which softened from kT~0.67 keV to ~0.18 keV in quiescence. This
unexpected result prompts us to examine the possibility that we have observed
an unrelated source, and we discuss the implications for AXPs, and magnetars in
general.Comment: 4 pages, 3 figures. To be published in the proceedings of the
conference "Isolated Neutron Stars: from the Interior to the Surface" (April
24-28, 2006, London, UK), eds. D. Page, R. Turolla, & S. Zan
The Fundamental Plane of Gamma-ray Globular Clusters
We have investigated the properties of a group of -ray emitting
globular clusters (GCs) which have recently been uncovered in our Galaxy. By
correlating the observed -ray luminosities with various
cluster properties, we probe the origin of the high energy photons from these
GCs. We report is positively correlated with the encounter rate
and the metalicity which place an
intimate link between the gamma-ray emission and the millisecond pulsar
population. We also find a tendency that increase with the energy
densities of the soft photon at the cluster location. Furthermore, the
two-dimensional regression analysis suggests that , soft photon
densities, and / possibly span fundamental
planes which potentially provide better predictions for the -ray
properties of GCs.Comment: 17 pages, 4 figures, 3 tables, published in Ap
Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope
We report the results from a detailed ray investigation in the field
of two "dark accelerators", HESS J1745-303 and HESS J1741-302, with years
of data obtained by the Fermi Large Area Telescope. For HESS J1745-303, we
found that its MeV-GeV emission is mainly originated from the "Region A" of the
TeV feature. Its ray spectrum can be modeled with a single power-law
with a photon index of from few hundreds MeV to TeV. Moreover,
an elongated feature, which extends from "Region A" toward northwest for
, is discovered for the first time. The orientation of this
feature is similar to that of a large scale atomic/molecular gas distribution.
For HESS J1741-302, our analysis does not yield any MeV-GeV counterpart for
this unidentified TeV source. On the other hand, we have detected a new point
source, Fermi J1740.1-3013, serendipitously. Its spectrum is apparently curved
which resembles that of a ray pulsar. This makes it possibly
associated with PSR B1737-20 or PSR J1739-3023.Comment: 11 pages, 7 figures, 2 tables, accepted for publication in MNRA
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