134 research outputs found
Fast Automatic Vehicle Annotation for Urban Traffic Surveillance
Automatic vehicle detection and annotation for streaming video data with complex scenes is an interesting but challenging task for intelligent transportation systems. In this paper, we present a fast algorithm: detection and annotation for vehicles (DAVE), which effectively combines vehicle detection and attributes annotation into a unified framework. DAVE consists of two convolutional neural networks: a shallow fully convolutional fast vehicle proposal network (FVPN) for extracting all vehicles' positions, and a deep attributes learning network (ALN), which aims to verify each detection candidate and infer each vehicle's pose, color, and type information simultaneously. These two nets are jointly optimized so that abundant latent knowledge learned from the deep empirical ALN can be exploited to guide training the much simpler FVPN. Once the system is trained, DAVE can achieve efficient vehicle detection and attributes annotation for real-world traffic surveillance data, while the FVPN can be independently adopted as a real-time high-performance vehicle detector as well. We evaluate the DAVE on a new self-collected urban traffic surveillance data set and the public PASCAL VOC2007 car and LISA 2010 data sets, with consistent improvements over existing algorithms
WI-FI MESH-AWARE DRONE CONTROLLER
Techniques are presented herein that support a mobile mesh encompassing a constellation of drones. Within such an arrangement, each drone carries a Wi-Fi access point (AP). Aspects of the techniques introduce the concept of a Wi-Fi mesh-aware mobile constellation controller (WFMAMCC) that not only intelligently dispatches Wi-Fi AP carrying drones (to, for example, minimize the number of drones required) but also optimally manages the mesh network that is carried on those drones (to, for example, ensure that, at all times, that mesh network supports a high level of performance and maintains backhaul connectivity). The techniques may find use in any number of sporting, entertainment, etc. settings where crowd size and fluidity may drive a need for temporary and dynamic Wi-Fi coverage
Molten Salt-Carbon Nanotube Thermal Energy Storage for Concentrating Solar Power Systems Final Report
We demonstrated that adding nanoparticles to a molten salt would increase its utility as a thermal energy storage medium for a concentrating solar power system. Specifically, we demonstrated that we could increase the specific heat of nitrate and carbonate salts containing 1% or less of alumina nanoparticles. We fabricated the composite materials using both evaporative and air drying methods. We tested several thermophysical properties of the composite materials, including the specific heat, thermal conductivity, latent heat, and melting point. We also assessed the stability of the composite material with repeated thermal cycling and the effects of adding the nanoparticles on the corrosion of stainless steel by the composite salt. Our results indicate that stable, repeatable 25-50% improvements in specific heat are possible for these materials. We found that using these composite salts as the thermal energy storage material for a concentrating solar thermal power system can reduce the levelized cost of electricity by 10-20%. We conclude that these materials are worth further development and inclusion in future concentrating solar power systems
Rotation profiles of solar-like stars with magnetic fields
The aim of this work is to investigate rotation profile of solar-like stars
with magnetic fields. A diffusion coefficient of magnetic angular momentum
transport is deduced. Rotating stellar models with different mass are computed
under the effect of the coefficient. Then rotation profiles are obtained from
the theoretical stellar models. The total angular momentum of solar model with
only hydrodynamic instabilities is about 13 times larger than that of the Sun
at the age of the Sun, and this model can not reproduce quasi-solid rotation in
the radiative region. However, not only can the solar model with magnetic
fields reproduce an almost uniform rotation in the radiative region, but its
total angular momentum is consistent with helioseismic result at the level of 3
at the age of the Sun. The rotation of solar-like stars with magnetic
fields is almost uniform in the radiative region. But there is an obvious
transition region of angular velocity between the convective core and the
radiative region of models with 1.2 - 1.5 , where angular velocity
has a sharp radial change, which is different from the rotation profile of the
Sun and massive stars with magnetic fields. Moreover the changes of the angular
velocity in the transition region increase with the increasing in the age and
mass.Comment: Accepted for publication in ChjA
Efficiently combining Machine Learning with OpenFOAM using SmartSim - Slides
Slides: 18th OpenFOAM Workshop - Efficiently combining Machine Learning with OpenFOAM using SmartSim1.
X-ray observations of sub-mm LABOCA galaxies in the eCDFS
We explore the X-ray properties of the 126 sub-mm galaxies (SMGs) of the
LABOCA survey in the CDFS and the eCDFS regions. SMGs are believed to
experience massive episodes of star-formation. Our goal is to examine whether
star-formation coexists with AGN activity, determine the fraction of highly
obscured AGN and finally to obtain an idea of the dominant power-mechanism in
these sources. Using Spitzer and radio arc-second positions for the SMGs, we
find 14 sources with significant X-ray detections. For most of these there are
only photometric redshifts available, with their median redshift being ~2.3.
Taking into account only the CDFS area which has the deepest X-ray
observations, we estimate an X-ray AGN fraction of <26+/-9 % among SMGs. The
X-ray spectral properties of the majority of the X-ray AGN which are associated
with SMGs are consistent with high obscuration, 10^23 cm-2, but there is no
unambiguous evidence for the presence of Compton-thick sources. Detailed
Spectral Energy Distribution fittings show that the bulk of total IR luminosity
originates in star-forming processes, although a torus component is usually
present. Finally, stacking analysis of the X-ray undetected SMGs reveals a
signal in the soft (0.5-2 keV) and marginally in the hard (2-5 keV) X-ray band.
The hardness ratio of the stacked signal is relatively soft (-0.40+/-0.10)
corresponding to a photon index of ~1.6. This argues against a high fraction of
Compton-thick sources among the X-ray undetected SMGs.Comment: 13 pages, to appear in A&
Shared Microexponents: A Little Shifting Goes a Long Way
This paper introduces Block Data Representations (BDR), a framework for
exploring and evaluating a wide spectrum of narrow-precision formats for deep
learning. It enables comparison of popular quantization standards, and through
BDR, new formats based on shared microexponents (MX) are identified, which
outperform other state-of-the-art quantization approaches, including
narrow-precision floating-point and block floating-point. MX utilizes multiple
levels of quantization scaling with ultra-fine scaling factors based on shared
microexponents in the hardware. The effectiveness of MX is demonstrated on
real-world models including large-scale generative pretraining and inferencing,
and production-scale recommendation systems
Formation of Millisecond Pulsars from Intermediate- and Low-Mass X-ray Binaries
We present a systematic study of the evolution of intermediate- and low-mass
X-ray binaries consisting of an accreting neutron star of mass and a donor star of mass . In our calculations we
take into account physical processes such as unstable disk accretion, radio
ejection, bump-induced detachment, and outflow from the point.
Comparing the calculated results with the observations of binary radio pulsars,
we report the following results. (1) The allowed parameter space for forming
binary pulsars in the initial orbital period - donor mass plane increases with
increasing neutron star mass. This may help explain why some MSPs with orbital
periods longer than days seem to have less massive white dwarfs than
expected. Alternatively, some of these wide binary pulsars may be formed
through mass transfer driven by planet/brown dwarf-involved common envelope
evolution. (2) Some of the pulsars in compact binaries might have evolved from
intermediate-mass X-ray binaries with anomalous magnetic braking. (3) The
equilibrium spin periods of neutron stars in low-mass X-ray binaries are in
general shorter than the observed spin periods of binary pulsars by more than
one order of magnitude, suggesting that either the simple equilibrium spin
model does not apply, or there are other mechanisms/processes spinning down the
neutron stars.Comment: 34 pages, 11 figures, accepted for publication in Ap
Field Measurements of Terrestrial and Martian Dust Devils
Surface-based measurements of terrestrial and martian dust devils/convective vortices provided from mobile and stationary platforms are discussed. Imaging of terrestrial dust devils has quantified their rotational and vertical wind speeds, translation speeds, dimensions, dust load, and frequency of occurrence. Imaging of martian dust devils has provided translation speeds and constraints on dimensions, but only limited constraints on vertical motion within a vortex. The longer mission durations on Mars afforded by long operating robotic landers and rovers have provided statistical quantification of vortex occurrence (time-of-sol, and recently seasonal) that has until recently not been a primary outcome of more temporally limited terrestrial dust devil measurement campaigns. Terrestrial measurement campaigns have included a more extensive range of measured vortex parameters (pressure, wind, morphology, etc.) than have martian opportunities, with electric field and direct measure of dust abundance not yet obtained on Mars. No martian robotic mission has yet provided contemporaneous high frequency wind and pressure measurements. Comparison of measured terrestrial and martian dust devil characteristics suggests that martian dust devils are larger and possess faster maximum rotational wind speeds, that the absolute magnitude of the pressure deficit within a terrestrial dust devil is an order of magnitude greater than a martian dust devil, and that the time-of-day variation in vortex frequency is similar. Recent terrestrial investigations have demonstrated the presence of diagnostic dust devil signals within seismic and infrasound measurements; an upcoming Mars robotic mission will obtain similar measurement types
The N. gonorrhoeae Type IV Pilus Stimulates Mechanosensitive Pathways and Cytoprotection through a pilT-Dependent Mechanism
The Neisseria gonorrhoeae type IV pilus is a retractile appendage that can generate forces near 100 pN. We tested the hypothesis that type IV pilus retraction influences epithelial cell gene expression by exerting tension on the host membrane. Wild-type and retraction-defective bacteria altered the expression of an identical set of epithelial cell genes during attachment. Interestingly, pilus retraction, per se, did not regulate novel gene expression but, rather, enhanced the expression of a subset of the infection-regulated genes. This is accomplished through mitogen-activated protein kinase activation and at least one other undefined stress-activated pathway. These results can be reproduced by applying artificial force on the epithelial membrane, using a magnet and magnetic beads. Importantly, this retraction-mediated signaling increases the ability of the cell to withstand apoptotic signals triggered by infection. We conclude that pilus retraction stimulates mechanosensitive pathways that enhance the expression of stress-responsive genes and activate cytoprotective signaling. A model for the role of pilus retraction in influencing host cell survival is presented
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