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- 2019
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Tidskriftsartikel (refereegranskat)
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- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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- Qian, Li-Bing, et al.
(författare)
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Transmission of electrons through the conical glass capillary with the grounded conducting outer surface
- 2017
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Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 66:12
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Tidskriftsartikel (refereegranskat)abstract
- The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i. e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial.. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the two-dimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm x 0.5 mm and a divergence of less than 0.35.. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 mu m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys: Si n: 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i. e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.
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- Wan, Cheng-Liang, et al.
(författare)
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Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary
- 2016
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Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 65:20
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Tidskriftsartikel (refereegranskat)abstract
- It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.
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- Ding, Guoru, et al.
(författare)
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Robust Online Spectrum Prediction With Incomplete and Corrupted Historical Observations
- 2017
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Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE. - 0018-9545 .- 1939-9359. ; 66:9, s. 8022-8036
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Tidskriftsartikel (refereegranskat)abstract
- A range of emerging applications, from adaptive spectrum sensing to proactive spectrum mobility, depend on the ability to foresee spectrum state evolution. Despite a number of studies appearing about spectrum prediction, fundamental issues still remain unresolved: 1) The existing studies do not explicitly account for anomalies, which may incur serious performance degradation; 2) they focus on the design of batch spectrum prediction algorithms, which limit the scalability to analyze massive spectrum data in real time; 3) they assume the historical data are complete, which may not hold in reality. To address these issues, we develop a Robust Online Spectrum Prediction (ROSP) framework, with incomplete and corrupted observations, in this paper. We first present data analytics of real-world spectrum measurements to reveal the correlation structures of spectrum evolution and to analyze the impact of anomalies on the rank distribution of spectrum matrices. Then, from a spectral–temporal 2-D perspective, we formulate the ROSP as a joint optimization problem of matrix completion and recovery by effectively integrating the time series forecasting techniques and develop an alternating direction optimization method to efficiently solve it. We apply ROSP to a wide range of real-world spectrum matrices of popular wireless services. Experiment results show that ROSP outperforms state-of-the-art spectrum prediction schemes.
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| 10. |
- He, Song, et al.
(författare)
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String Amplitudes from Field-Theory Amplitudes and Vice Versa
- 2019
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 122:21
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Tidskriftsartikel (refereegranskat)abstract
- We present an integration-by-parts reduction of any massless tree-level string correlator to an equivalence class of logarithmic finzctions, which can be used to define a field-theory amplitude via a Cachazo-He-Yuan (CHY) formula. The string amplitude is then shown to be the double copy of the field theory one and a special disk or sphere integral. The construction is generic as it applies to any correlator that is a rational function of correct SL(2) weight. By applying the reduction to open bosonic or heterotic strings, we get a closed-form CHY integrand for the (DF)(2) + Yang-Mills + phi(3) theory.
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