395 research outputs found
Planar Object Tracking in the Wild: A Benchmark
Planar object tracking is an actively studied problem in vision-based robotic
applications. While several benchmarks have been constructed for evaluating
state-of-the-art algorithms, there is a lack of video sequences captured in the
wild rather than in constrained laboratory environment. In this paper, we
present a carefully designed planar object tracking benchmark containing 210
videos of 30 planar objects sampled in the natural environment. In particular,
for each object, we shoot seven videos involving various challenging factors,
namely scale change, rotation, perspective distortion, motion blur, occlusion,
out-of-view, and unconstrained. The ground truth is carefully annotated
semi-manually to ensure the quality. Moreover, eleven state-of-the-art
algorithms are evaluated on the benchmark using two evaluation metrics, with
detailed analysis provided for the evaluation results. We expect the proposed
benchmark to benefit future studies on planar object tracking.Comment: Accepted by ICRA 201
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Evaluating soil nitrate dynamics in an intercropping dripped ecosystem using HYDRUS-2D.
The competition mechanisms between crop species for water and nutrients, especially nitrate (NO3-N), in intercropping ecosystems are still poorly understood. Therefore, an experiment involving high (300 kg ha-1 for corn and 250 kg ha-1 for tomato), medium (210 kg ha-1 for corn and 175 kg ha-1 for tomato), and low (150 kg ha-1 for corn and 125 kg ha-1 for tomato) N-fertilizer applications (HF, MF, LF, respectively) was conducted in the corn and tomato intercropping ecosystem during 2014 (a calibration period for modeling) and 2015 (a validation period for modeling). The modified HYDRUS-2D code was used to analyze soil NO3-N concentrations (SNC) in the middle between corn rows (Pc), between corn and tomato rows (Pb), and between tomato rows (Pt), NO3-N exchange in the horizontal direction between different regions, NO3-N leaching from the corn, the bare, and the tomato region, and N uptake by crops. Simulated SNCs were in good agreement with measurements, with RMSE, NSE, and MRE of 0.01-0.06 mg cm-3, 0.75-0.98, and 8.7-19.1%, respectively, during the validation period (2015). Average SNCs in the 0-40 cm soil layer were different between Pc, Pt, and Pb. Intensive NO3-N exchange in the horizontal direction occurred during the second stage (Day After Sowing [DAS] 37-113 in 2014; DAS 29-120 in 2015). NO3-N exchange between the corn and bare regions was lower than between the tomato and bare regions due to smaller concentration gradients. However, in the vertical direction, NO3-N leaching from the corn region in both years was 4.1 and 8.8 times larger, respectively, than from the tomato region under HF since NO3-N mainly moved from the tomato region to the corn region. Our results reveal the competition between corn and tomato for N and provide a rationale for formulating and optimizing different fertilizer regimes for different crops in the intercropping ecosystem
Mode entanglement of electrons in the one-dimensional Frenkel-Kontorova model
We study the mode entanglement in the one-dimensional Frenkel-Kontorova
model, and found that behaviors of quantum entanglement are distinct before and
after the transition by breaking of analyticity. We show that the more extended
the electron is, the more entangled the corresponding state. Finally, a
quantitative relation is given between the average square of the concurrence
quantifying the degree of entanglement and the participation ratio
characterizing the degree of localization.Comment: 4 pages, 4 figures. V
Dynamic behavior analysis and time delay feedback control of gear pair system with backlash non-smooth characteristic
The present work investigates the non-smooth vibration characteristic and time delay feedback control of a gear pair system involving backlash and time-varying mesh stiffness. Firstly, a gear pair model with backlash non-smooth characteristic is established. Then in combination with the discontinuity mapping method, Floquet theory is presented to determine the stability and bifurcation of periodic response, and the period doubling bifurcation has been accurately predicted. Moreover, the maximal Lyapunov exponent is obtained to determine the chaos state in gear pair system which is conform to the bifurcation diagram and Poincare section. Finally, a time delay feedback is introduced to control the dynamic behaviors of the system, and numerical simulation results show that the system can be effectively controlled from chaotic motion into stable periodic motion by increasing the delay feedback gain or delay time
Deep Imaging of the HCG 95 Field.I.Ultra-diffuse Galaxies
We present a detection of 89 candidates of ultra-diffuse galaxies (UDGs) in a
4.9 degree field centered on the Hickson Compact Group 95 (HCG 95) using
deep - and -band images taken with the Chinese Near Object Survey
Telescope. This field contains one rich galaxy cluster (Abell 2588 at
=0.199) and two poor clusters (Pegasus I at =0.013 and Pegasus II at
=0.040). The 89 candidates are likely associated with the two poor clusters,
giving about 50 60 true UDGs with a half-light radius kpc
and a central surface brightness mag arcsec. Deep
'-band images are available for 84 of the 89 galaxies from the Dark Energy
Camera Legacy Survey (DECaLS), confirming that these galaxies have an extremely
low central surface brightness. Moreover, our UDG candidates are spread over a
wide range in color, and 26% are as blue as normal star-forming
galaxies, which is suggestive of young UDGs that are still in formation.
Interestingly, we find that one UDG linked with HCG 95 is a gas-rich galaxy
with H I mass detected by the Very Large Array,
and has a stellar mass of . This
indicates that UDGs at least partially overlap with the population of nearly
dark galaxies found in deep H I surveys. Our results show that the high
abundance of blue UDGs in the HCG 95 field is favored by the environment of
poor galaxy clusters residing in H I-rich large-scale structures.Comment: Published in Ap
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