whu-nercms at trecvid2021:instance search task

We will make a brief introduction of the experimental methods and results of the WHU-NERCMS in the TRECVID2021 in the paper. This year we participate in the automatic and interactive tasks of Instance Search (INS). For the automatic task, the retrieval target is divided into two parts, person retrieval, and action retrieval. We adopt a two-stage method including face detection and face recognition for person retrieval and two kinds of action detection methods consisting of three frame-based human-object interaction detection methods and two video-based general action detection methods for action retrieval. After that, the person retrieval results and action retrieval results are fused to initialize the result ranking lists. In addition, we make attempts to use complementary methods to further improve search performance. For interactive tasks, we test two different interaction strategies on the fusion results. We submit 4 runs for automatic and interactive tasks respectively. The introduction of each run is shown in Table 1. The official evaluations show that the proposed strategies rank 1st in both automatic and interactive tracks.Comment: 9 pages, 4 figure

Strain-restricted transfer of ferromagnetic electrodes for constructing reproducibly superior-quality spintronic devices

Spintronic device is the fundamental platform for spin-related academic and practical studies. However, conventional techniques with energetic deposition or boorish transfer of ferromagnetic metal inevitably introduce uncontrollable damage and undesired contamination in various spin-transport-channel materials, leading to partially attenuated and widely distributed spintronic device performances. These issues will eventually confuse the conclusions of academic studies and limit the practical applications of spintronics. Here we propose a polymer-assistant strain-restricted transfer technique that allows perfectly transferring the pre-patterned ferromagnetic electrodes onto channel materials without any damage and change on the properties of magnetism, interface, and channel. This technique is found productive for pursuing superior-quality spintronic devices with high controllability and reproducibility. It can also apply to various-kind (organic, inorganic, organic-inorganic hybrid, or carbon-based) and diverse-morphology (smooth, rough, even discontinuous) channel materials. This technique can be very useful for reliable device construction and will facilitate the technological transition of spintronic study

Low-profile patch antennas with enhanced horizontal omnidirectional gain for DSRC applications

Here, a low-profile microstrip patch antenna with vertical polarisation and over 3 dB enhanced gain in the horizontal plane is proposed for dedicated short-range communications (DSRC) application. It is a centre-fed circular patch antenna coupled by an annular ring and shorted concentrically with a set of shorting vias. For further increasing the gain in the horizontal plane, six groups of microstrip patches with one edge open and three edges shorted, which work as magnetic dipole antennas, are laid around the shorted circular patch-ring antenna (SCPRA). These gain enhancement elements resonate at 5.9 GHz and guide the TM wave along the horizontal surface. In addition, an equivalent circuit model of SCPRA is presented as a tool for easier impedance matching. The number of gain enhancement elements in each group can be adjusted to achieve variable radiation patterns in the horizontal plane. Two antennas achieving omnidirectional and quasi-elliptical radiation patterns are proposed, simulated, and measured. The measured results agree well with the simulated results, and the quasi-elliptical radiation patterns in the horizontal plane of the antenna demonstrate the desirable performance for DSRC applications.Published versio

Wideband circular patch antenna with Ishaped structure for horizontal omnidirectional gain enhancement

A wideband circular patch antenna with enhanced omnidirectional gains in the horizontal plane is presented. The gain enhancement over 1 GHz bandwidth is achieved by loading a low-profile 'I-shaped' structure (ISS) without increasing antenna's thickness. The effective refractive index of the ISS is larger, over a wide bandwidth than that of the conventional substrate with the same material. Therefore, the artificial structure behaves as a lens to refract the electromagnetic wave which is parallelly incident to the ISS and thus is able to concentrate the energy and enhance the antenna's horizontal radiation performance. In addition, the proposed antenna achieves a relative bandwidth of 19% through combining the resonant frequency for the TM₀₁ mode and another resonant frequency excited by the coupling between the circular patch and the unit cells for verifying the wideband gain enhancement of the ISS. Both simulation and measurement results indicate that the proposed antenna achieves 0.5-2.0 dB gain increment within the operating bandwidth compared with the unloaded antenna on the same ground

Grid-Free Modelling Based on the Finite Particle Method for Incompressible Viscous Flow Problems

In this paper, we present a grid-free modelling based on the finite particle method for the numerical simulation of incompressible viscous flows. Numerical methods of interest are meshless Lagrangian finite point scheme by the application of the projection method for the incompressibility of the Navier–Stokes flow equations. The moving least squares method is introduced for approximating spatial derivatives in a meshless context. The pressure Poisson equation with Neumann boundary condition is solved by the finite particle method in which the fluid domain is discretized by a finite number of particles. Also, a continuous particle management has to be done to prevent particles from moving into configurations problematic for a numerical approximation. With the proposed finite particle technique, problems associated with the viscous free surface flow which contains the study on the liquid sloshing in tanks with low volumetric fluid type, solitary waves movement, and interaction with a vertical wall in numerical flume as well as the vortex patterns of the ship rolling damping are circumvented. These numerical models are investigated to validate the presented grid-free methodology. The results have revealed the efficiency and stability of the finite particle method which could be well handled with the incompressible viscous flow problems

A Deployable Wideband Differential-Fed Dual-Polarized Patch Antenna Array

In this paper, a deployable wideband differential-fed dual-polarized high-isolation patch antenna array is proposed. To achieve dual polarization, every element has two pairs of differential ports. Because of the differential design, the couplings from the adjacent ports (the other pair of ports) are canceled and high isolation between the two polarization is achieved. In addition, capacitive feeds are applied to enhance the bandwidth. By integrating with two planar Marchand baluns, the two pairs of the differential ports are excited for dual polarization. Then, the wideband dual-polarization patch antenna element is expanded to a $4\times 4$ antenna array for better gain. In order to achieve deployment, we present a novel foldable mechanism suitable for low-frequency patch antenna array, which is different from the conventional design on the flexible printed board. The deployment concept is presented. One prototype is fabricated and measured. Its operating band is from 1.15 GHz to 1.35 GHz. The peak gains of the two polarizations are 14.4 dBi and 14.1 dBi respectively

Discovery and geological significance of gas-liquid spouting expulsion and effusion depositional structures at Xialei manganese deposit in Guangxi

The Daxin Xialei Devonian manganese deposit in Guangxi is the first super-massive manganese ore deposit ever discovered in China. Here we conducted detailed petrographic studies on manganese-bearing sequence, ore mineral assemblages and their textures and structures. Our work reveal that the brecciated, vein-bearing and stockwork manganese ore minerals may form correspondingly to the expulsion and effusion of the gas and liquid-rich fluid. In addition, prevailing manganese-bearing silicate and sulfide minerals (rhodonite, manganese-iron chlorophyllite, pyrite, chalcopyrite, manganite, etc.) of hydrothermal origin are observed among the ores. Further comprehensive examinations of the original borehole data of the mining area lead to two major outcomes.First, three syndepositional faults are successfully recovered and identified in Late Devonian Xialei-Tuhu Ⅳ-graben basins, which controls the formation and spatial distribution of the manganese ore deposit.Second, brecciated manganese ore minerals appear to be clustered in space, and the localities of which may correspond to the locations of the ancient gas-liquid expulsion and effusion centers that give rise to the formation of manganese ore. Notably, the spatial distribution of the fossilized gas-liquid centers is controlled by the syndepositional faults developed during the formation of manganese ore deposit. Given the observation that Xalei Devonian manganese ore deposit shares comparable expulsion and effusion depositional features to Nanhua Datangpo gas-liquid depositional manganese ore deposit at Songtao of Guizhou Province, it is therefore argued that both Xialei and Datangpo manganese ore developed by similar mechanisms. This study sheds light on a better understanding of the metallogenic mechanism(s) and will place better constraints on the future explorations of Xialei manganese ore deposit

Physics-Based Electrothermal Stress Evaluation Approach of IGBT Modules Combined With Artificial Neural Network Model

Due to the disparate timescale behavior in the electrical and thermal aspects, achieving a balance between simulation efficiency and accuracy in electrothermal analysis of insulated gate bipolar transistor (IGBT) modules has been a challenging task. A physical-based electrothermal stress evaluation approach combining with artificial neural network (ANN) model is proposed in this article, which significantly improves performance in circuit simulation. The training data for ANN models are derived from the Hefner physical model, a well-established model integrated in Saber. By re-expressing the Hefner model using MATLAB scripts, high-precision data can be efficiently obtained. Double-pulse experiments show that the switching transient characterized by the Hefner model have high precision, with an error within 5% compared to the experimental data. Additionally, the transient behavior of IGBT devices is further described by a two-layer feed-forward ANN, trained using datasets obtained by varying parasitic or operating parameters in the re-expressed Hefner model. Combining the physical model with the ANN models, the proposed approach can simulate not only transient electrical behavior but also long-term thermal behavior with accurate switching energy. This approach has been implemented in MATLAB/Simulink and verified with Saber for system-level circuit simulation. The electrothermal stress evaluation results show that the simulation efficiency is significantly improved (180 times faster than Saber under the simulation settings in this article), while maintaining high precision, and the error is within 2.5%. Experimental results also validate the accuracy of proposed model in predicting the voltage and current stress, with a maximum error of 1.5%