Tao Chen

• Chinese Academy of Sciences

Under northward interplanetary magnetic field, periodical fluctuations with the period of 85 s have been observed by one of the Time History of Events and Macroscale Interactions during Substorms spacecraft at the dayside magnetopause when the solar wind dynamic pressure suddenly dropped. The observed magnetic field distortions, characterized by th...

Image matting is widely studied for accurate foreground extraction. Most algorithms, including deep-learning based solutions, require a carefully edited trimap. Recent works attempt to combine the segmentation stage and matting stage in one CNN model, but errors occurring at the segmentation stage lead to unsatisfactory matte. We propose a user-gui...

Within a Kelvin‐Helmholtz (K‐H) vortex at the duskside magnetopause, a substructure characterized by two flux enhancements of cold magnetosheath plasma in a background of hot magnetosphere plasma is observed. The substructure is accompanied by plasma transport across the magnetopause, and the transport region is found to split into two parts: the d...

We introduce an interactive technique to extract and manipulate simple 3D shapes in a single photograph. Such extraction requires an understanding of the shape's components, their projections, and their relationships. These cognitive tasks are simple for humans, but particularly difficult for automatic algorithms. Thus, our approach combines the co...

Scene recognition applications on mobile devices receive increasing attentions in recent years. Due to mobile users' real-time requirement, an accurate and efficient scene recognition system is urgent for mobile applications. In this paper, we propose a novel discriminative codeword selection method by using the ensemble extreme learning machine (E...

High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere, and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well. The High-Energy Electron Flux (HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed toge...

Utilizing associated observations of Geotail and ACE satellites from the year of 1998 to 2005, we investigated the X-lines in the near-Earth tail under different interplanetary magnetic field (IMF) conditions. The X-lines are recognized by the tailward fast flows (TFF) with negative Bz. Statistically, the X-lines in the tail can be observed for sou...

L. Q. Zhang, W. Baumjohann, J. Y. Wang, H. Rème, M. W. Dunlop, and T. Chen

Automatically recognizing a place or landmark attracts increasing attentions in recent years due to its wide applications in mobile terminals. In this paper, we consider the problem of landmark recognition using sparse representation in compressed sensing. After constructing the dictionary with training samples, the recognition of a query landmark...

In this paper, we statistically analyzed and compared the earthward flow (EF) and the tailward flow (TF) in the plasma sheet. It is found that the properties of the EF/TF in the central plasma sheet (CPS) of β>1 and the outer plasma sheet (OPS) of 0.1<β<1 are distinctly different. The main conclusions include that: 1) the EF occur in both the CPS a...

With the rapid development of digital image editing tools, the authenticity of digital images becomes questionable in recent years. Image tampering detection is a technology that detects tampered images by using intrinsic image regularities. However, existing intrinsic image regularities are designed for one specific type of tampering operations. W...

Along with the rapid development of mobile terminal devices, landmark recognition applications based on mobile devices have been widely researched in recent years. Due to the fast response time requirement of mobile users, an accurate and efficient landmark recognition system is thus urgent for mobile applications. In this paper, we propose a landm...

An ion flux dropout near the dipolarization front (DF) at around X GSM = −11 RE in the Earth’s plasma sheet was observed by Time History of Events and Macroscale Interaction during substorms (THEMIS) on March 31, 2009. The ion differential energy fluxes at energies from 450 eV to 150 keV measured by the ESA and SST instruments from THC began to dec...

THEMIS observed several magnetopause crossings periodically at the duskside of magnetopause under southward IMF, with significant sunward returning flows inside the magnetopause. The vortex features of the flows and the periodic enhancements in the calculated vorticity normal to the spacecraft plane could be found in the observation. The distortion...

This paper proposes a new bag-of-visual phrase (BoP) approach for mobile landmark recognition based on discriminative learning of category-dependent visual phrases. Many previous landmark recognition works adopt a bag-of-words (BoW) method which ignores the co-occurrence relationship between neighboring visual words in an image. Although some works...

This paper proposes a new soft bag-of-words (BoW) method for mobile landmark recognition based on discriminative learning of image patches. Conventional BoW methods often consider the patches/regions in the images as equally important for learning. Amongst the few existing works that consider the discriminative information of the patches, they main...

In recent years, the computer graphics and computer vision communities have devoted significant attention to research based on Internet visual media resources. The huge number of images and videos continually being uploaded by millions of people have stimulated a variety of visual media creation and editing applications, while also posing serious c...

A substorm dispersionless injection event observed during the storm recovery phase on 11 March 1998 at geosynchronous orbit is carefully studied. The event shows the notable characteristics that for energetic ions the flux enhancement ratio before and after injection increases and remains elevated with increasing energy, while for energetic electro...

We present PoseShop - a pipeline to construct segmented human image database with minimal manual intervention. By downloading, analyzing, and filtering massive amounts of human images from the Internet we achieve a database which contains 400 thousands human figures that are segmented out of their background. The human figures are organized based o...

Bag-of-visual phrase (BoP) has been proposed and developed for landmark recognition recently. However, existing BoP methods for landmark recognition have two major shortcomings: (i) they try to construct a universal phrase vocabulary for all object categories, which lacks specific descriptive capabilities for a particular category, and (ii) they of...

This paper proposes a new information fusion approach that employs two information components for mobile landmark recognition, which includes: content analysis and context analysis. Existing landmark recognition works are mainly based on PC platform, which uses content analysis alone for recognition, and thus has a large computation cost and cannot...

This paper proposes a new approach for mobile landmark recognition based on integrated content and context analysis. Conventional scene/landmark recognition methods fo- cus mainly on nonmobile desktop/PC platform, where content analysis alone is used to perform landmark recognition. These nonmobile systems, however, do not take unique features of m...

This paper proposes a discriminative learning bags-of-words (BoW) approach for mobile landmark recognition at patch and image levels. Conventional methods often treat the local patches and images equally important for recognition and do not differentiate their different importance. Although there exist several works that consider the patches' discr...

This paper proposes an adaptive bag-of-phrases (BoP) algorithm for mobile scene recognition based on bag-of-words approach. Conventional BoW methods do not consider the dependence and pairwise relationship among different codewords. However, these contextual relations between pairwise codewords play an important role for users to recognize an image...

The magnetic field dipolarization in the vicinity of substorm onset and during substorm expansion phase during the period of 06:00–06:40 UT on 15 February 2008 is investigated with observations from multiple probes of THEMIS. It is found that the magnetic dipolarization at the substorm onset (the onset time was about 06:14 UT) was not accompanied b...

The relationship between the average structure of the inner magnetospheric large-scale electric field and geomagnetic activity levels has been investigated by Double Star TC-1 data for radial distances ρ between 4.5 RE and 12.5 RE and MLT between 18:00 h and 06:00 h from July to October in 2004 and 2005. The sunward component of the electric field...

Mobile-based landmark recognition is becoming increasingly appealing due to the proliferation of mobile devices coupled with improving processing techniques, imaging capability, and networking infrastructure. This article provides a general overview of existing mobile-based and nonmobile-based landmark recognition systems and their differences. We...

The growing usage of mobile camera phones has led to proliferation of many mobile applications. Landmark recognition is one of the mobile applications that are gaining more attention in recent years. The main idea of the application is that a user will use a camera phone to capture the image of a landmark or building and then the system will analyz...

We present a system that composes a realistic picture from a simple freehand sketch annotated with text labels. The composed picture is generated by seamlessly stitching several photographs in agreement with the sketch and text labels; these are found by searching the Internet. Although online image search generates many inappropriate results, our...

Applying ACE data and pressure-corrected Dst index (Dst*), annual distributions of solar wind structures detected at L1 point (the first Lagrangian point between solar-terrestrial interval) and correlations between solar wind structures and geomagnetic storms in 1998–2008 have been studied. It was found that, within the Earth's upstream solar wind,...

We present a system for vectorizing 2D raster format cartoon animations. The output animations are visually flicker free, smaller in file size, and easy to edit. We identify decorative lines separately from colored regions. We use an accurate and semantically meaningful image decomposition algorithm, supporting an arbitrary color model for each reg...

The growing usage of mobile devices has led to proliferation of many mobile applications. A growing trend in mobile applications is centered on mobile landmark recognition. It is a new mobile application that recognizes a captured landmark using the mobile device and retrieves related information. This paper will present a survey on mobile landmark...

Video structure analysis is a basic requirement for most content-based video editing and processing systems. This paper presents a fast video structure analysis method based on image segmentation in each frame, with region matching between frames. The structure analysis decomposes the video into several moving objects, including information about t...

A big magnetic storm with Dst of order --472 nT occurred on November 20 2003 Cluster spacecrafts passed through the magnetopause at about 16 13 20 on the dusk flank and crossed low-latitude boundary layer LLBL between 14 40 00 and 16 13 20 The dusk electric field component E dusk was observed in the LLBL magnetopause and magnetosheath The E dusk is...

1] A compiled empirical global Joule heating (CEJH) model is described in this study. This model can be used to study Joule heating patterns, Joule heating power, potential drop, and polar potential size in the high-latitude ionosphere and thermosphere, and their variations with solar wind conditions, geomagnetic activities, the solar EUV radiation...

A big magnetic storm with Dst of order - 472 nT occurred on November 20, 2003. Cluster spacecrafts passed through the magnetopause at about 16:33:20 on the dusk flank, and crossed LLBL between 14:4:00 and 16:13:20. The dusk electric field component Edusk was observed in LLBL. Edusk is about order of 0 °C 45 mV/m during big magnetic storm, but Edusk...

Ion equatorial flux distributions, inverted from energetic neutral atom (ENA) images in different energy channels obtained by the HENA imager on the IMAGE satellite, are used to deduce the plasma ion temperature in the ring current. During the early period of the recovery phase of the strong storm on 12 August 2000, the deduced ion temperatures of...

We describe how a local plasma structure can be changed by a transverse shear flow using numerical simulation to investigate the disturbance process near the magnetopause. The results show that magnetic field lines are bent by transverse shear flow disturbance near the current sheet region. There are multiple bipolar structures of the normal magnet...

We propose that the appropriate instability to trigger a substorm is a tailward meander (in the equatorial plane) of the strong current filament that develops during the growth phase. From this single assumption follows the entire sequence of events for a substorm. The main particle acceleration mechanism in the plasma sheet is curvature drift with...

It is supposed that local and transient reconnection in the plasma boundary layer can be caused by the impact and switch-off of a single directional transverse shear flow. MHD (magnetohydrodynamic) simulation is used to investigate the reconnection processes in the two cases. It is found that if the inflow is homogeneous, it does not cause reconnec...

An important role of velocity shear in producing transient magnetic reconnection in the magneto- pause boundary layer region is supposed. Two kinds of velocity shears may be there in the magnetopause boundary layer: the velocity shear of field-aligned flow occuring at the high latitude boundary layer region in the dayside magnetopause outside the s...

We propose a trapped-ball method for image segmentation, which is fast, supports non-uniformly colored regions, and allows robust region segmentation even in the presence of imperfectly linked region edges. We also introduce two applications by using the trapped-ball image segmentation, for temporal coherent animations generation and editing. First...