深度视觉目标跟踪进展综述

视频目标跟踪是计算机视觉领域的一个重要研究课题.近年来,随着深度学习在视觉目标跟踪领域获得了巨大的成功,一系列优秀的深度跟踪算法涌现出来.本文回顾了近年来深度目标跟踪领域的进展.首先,我们详细讨论了近十年来跟踪领域数据集的发展趋势,这些数据集不仅全面地评估了算法性能同时为模型训练提供了极大的便利.其次,我们分类讨论了几大类经典的深度学习跟踪框架,包括深度相关滤波器跟踪、分类式网络跟踪、双路网络跟踪、基于梯度的深度跟踪算法以及基于Transformer的跟踪算法.最后,我们对全文内容进行总结,并指出未来的发展趋势.

长挡板结构型式对竖缝式鱼道鱼池流速影响研究

大坝和堤堰等水工建筑物的修建截断了河流,使河流中鱼类的栖息地及洄游路线受到极为严重的干扰。为了解决鱼类的洄游问题,修建鱼道是广泛采用的工程措施,其中,以竖缝式鱼道的数量居多。本文从竖缝式鱼道的长挡板细部构造入手,通过模型实验的手段,对比分析了三种方案对竖缝式鱼道鱼池流速的影响。通过研究,推荐竖缝式鱼道的长挡板结构型式为“直钩”型。

Asymmetric Mesoporous Carbon Microparticles by 3D-Confined Self-Assembly of Block Copolymer/Homopolymer Blends and Selective Carbonization

Shape control of mesoporous carbon microparticles(MCMPs)is of critical importance;in particular,asymmetric shapes that can yield unique properties have attracted significant attention.However,the tailored synthesis of asymmetric MCMPs with ordered structures remains challenging.Herein,we report a facile route to prepare asymmetric MCMPs by dynamic neutral interface-guided 3D-confined self-assembly(3D-CSA)of block copolymer/homopolymer(BCP/hP)blends,followed by a self-templated selective direct carbonization strategy.BCP/h P Janus microparticles with ordered hierarchical mesostructures were prepared with emulsion solvent evaporation-induced 3D-CSA.The continuous phase of BCP domains was then crosslinked.Composite asymmetric MCMPs are successfully generated after selective carbonization of the crosslinked continuous phase.This method allows tuning the shape of MCMPs easily by varying the blending ratio of BCP/h P.The composite asymmetric MCMPs combine the advantages of asymmetric shape,ordered structure,high specific surface area,chemical inertness and thermal stability and could provide great possibilities for applications in catalysis,drug delivery,energy conversion and storage.

Kinetically Controlled Supramolecular Block Copolymer Self-Assembly:Multicolor Photonic Crystal Patterns from a Single Formulation

Photonic crystal(PC)patterns with tunable and changeable nonvolatile structural colors printed from a single ink are of great interest for optical products but have rarely been reported because most inks can only output one respective structural color.Herein,we propose a facile yet effective kinetically controlled self-assembly strategy to address this challenge.An ink formulation containing supramolecular block copolymers(SBCPs)is developed.SBCP patterns were printed by direct-ink-writing followed by solvent annealing to generate different structural colors by simply controlling the annealing time.The self-assembly kinetic regime suggests that different colors result from various kinetically trapped metastable states.In turn,the variation in structural color enables“visualization”of the self-assembly dynamics.Furthermore,we demonstrate that these kinetically trapped structures exhibit different responsive color-change behaviors.In addition,this kinetic control strategy can be synergistic with thermodynamic control to extend the color range.This study provides a facile yet effective solution for well-designed PC patterns with tunable,responsive,and unfading colors printed from the simplest single-nozzle printer with a single colorless ink,presenting great potential in broad applications,including information storage,encryption,and anti-fake.

Hydraulics and swimming behavior of schizothorax prenanti in vertical slot fishways

This paper presents a novel experiment for the correlation between the hydraulics and the swimming behavior of Schizothorax prenanti,a rare species of fish in southwest China,in passing a vertical slot fishway.With an acoustic Doppler velocimeter,the velocities of a physical model in the equidimension fishway in the Shaping II power station are measured.The hydraulic parameters include the hydraulic head drop,the velocity patterns and the flow rate,and the swimming behavior includes the burst-coast,the sustained swimming and the migratory path,and they are analyzed under the test conditions.The sustained swimming velocity is in the range from 0.65m/s to 1.09m/s.The estimated hydraulic head drop of each pool is calculated and is in the range from 0.08-0.11 m,which means that 2.6% slope is reasonable.For the same slope,the maximum velocity is further reduced from 1.24 m/s to 1.14 m/s by using an L shape baffle structure.The above findings are used as the basis to evaluate the hydraulic performance of the fishways,where the L shape baffle structure is expected to be effective tor creating a preterencial flow for the fish.For the main stream of the pool,an "Ω" shape flow pattern is more fish-friendly,which can effectively extend the energy dissipation distance and avoid the bursting through a high velocity zone.This paper provides a useful complementary tool for practical designs.

Polymersome formation by solvent annealing-induced structural reengineering under 3D soft confinement

A solvent annealing-induced structural reengineering approach is exploited to fabricate polymersomes from block copolymers that are hard to form vesicles through the traditional solution self-assembly route.More specifically,polystyrene-b-poly(4-vinyl pyridine)(PS-b-P4VP)particles with sphere-within-sphere structure(SS particles)are prepared by three-dimensional(3D)soft-confined assembly through emulsion-solvent evaporation,followed by 3D soft-confined solvent annealing upon the SS particles in aqueous dispersions for structural engineering.A water-miscible solvent(e.g.,THF)is employed for annealing,which results in dramatic transitions of the assemblies,e.g.,from SS particles to polymersomes.This approach works for PS-b-P4VP in a wide range of block ratios.Moreover,this method enables effective encapsulation/loading of cargoes such as fluorescent dyes and metal nanoparticles,which offers a new route to prepare polymersomes that could be applied for cargo release,diagnostic imaging,and nanoreactor,etc.