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FLUID-STRUCTURE INTERACTION OF HYDRODYNAMIC DAMPER DURING THE RUSH INTO THE WATER CHANNEL

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Journal of Hydrodynamics 2008年第5期20卷 583-590页

作者： XU qing-xin shen Rong-ying State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240China

The hydrodynamic damper is a device to decrease the motion of armament carrier by use of the water resistance. When hydrodynamic damper rushes into the water channel with high velocity, it is a complicated flow phenomenon with fluid-structure interaction, free surface and moving interface. Numerical simulation using the Smoothed Particle Hydrodynamics （SPH） method coupled with the Finite Element （FE） method was successfully conducted to predict the dynamic characteristics of hydrodynamic damper. The water resistance, the pressure in the interface and the stress of structure were investigated, and the relationship among the peak of water resistance, initial velocity and actual draught was also discussed. The empirical formula was put forward to predict the water resistance. And it is found that the resistance coefficient is commonly in the range of 0.3 ≤ C ≤ 0.5, when the initial velocity is larger than 50 m/s. It can be seen that the SPH method coupled with the FE method has many obvious advantages over other numerical methods for this complicated flow problem with fluid-structure interaction.

关键词： hydrodynamic damper fluid-structure interaction Smoothed Particle Hydrodynamics (SPH) method Finite Element (FE) method

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谈波速与波长变换及其物理意义

大学物理 2024年第6期43卷 6-8,15页

作者：周强申庆徽刘静山东科技大学电子信息工程学院山东青岛266590

关于波速与波长变换,一些文献中虽有论述,但所得表达式太复杂而不宜记忆,且未涉及其物理意义.本文由四维波矢的洛伦兹变换来分析这一问题,通过引入波速因子和综合速度因子的概念,得到容易记忆的简单表达式,并力求阐明其物理意义,最后说... 详细信息

关于波速与波长变换,一些文献中虽有论述,但所得表达式太复杂而不宜记忆,且未涉及其物理意义.本文由四维波矢的洛伦兹变换来分析这一问题,通过引入波速因子和综合速度因子的概念,得到容易记忆的简单表达式,并力求阐明其物理意义,最后说明其应用.

关键词：四维波矢波速因子综合速度因子

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Response of Cultural Lake Eutrophication to Hemp-retting in Quidenham Mere of England in Post-Medieval

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Chinese Geographical Science 2007年第1期17卷 69-74页

作者： CHENG Xiaoying LI Shijie shen qing XUE Jing The Key Laboratory of Industrial Biotechnology Ministry of Education Southern Yangtze University Wuxi 214122 China School of Biotechnology Southern Yangtze University Wuxi 214122 China Nanjing Institute of Geography ＆ Limnology Chinese Academy of Sciences Nanjing 210008 China

To study the influence of human activity on natural lake, chironomid fauna change in the 700-560cm lake sediment in Quidenham Mere of England associated with chironomid inferred TP presented that the lake experienced a whole eutrophication process due to human hemp-retting in Post-Medieval based on the history record and pollen analysis, which was confirmed by mollusc and ostracod analysis. However, the response of chironomid and mollusc to retting was the strongest with ostracod a little behind. It proved that cultural eutrophication existed in history and could be recovered by itself despite of some long-term unachievahle destroy. And it was most important for external nutrient to be cut off during lake restoration even in ancient times.

关键词： chironomid cultural lake eutrophication ancient times Quidenham Mere

Steering control for underwater gliders

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Frontiers of Information Technology & Electronic Engineering 2017年第7期18卷 898-914页

作者： You LIU qing shen Dong-li MA Xiang-jiang YUAN School of Aeronautic Science and Engineering Beihang University Beijing 100191 China Institution of China Academy of Aerospace Aerodynamics Beijing 100074 China

Steering control for an autonomous underwater glider （AUG） is very challenging due to its changing dynamic char- acteristics such as payload and shape. A good choice to solve this problem is online system identification via in-field trials to capture current dynamic characteristics for control law reconfiguration. Hence, an online polynomial estimator is designed to update the yaw dynamic model of the AUG, and an adaptive model predictive control （MPC） controller is used to calculate the optimal control command based on updated estimated parameters. The MPC controller uses a quadratic program （QP） to compute the optimal control command based on a user-defined cost function. The cost function has two terms, focusing on output reference tracking and move suppression of input, respectively. Move-suppression performance can, at some level, represent energy-saving performance of the MPC controller. Users can balance these two competitive control performances by tuning weights. We have compared the control performance using the second-order polynomial model to that using the filth-order polynomial model, and found that the tbrmer cannot capture the main characteristics of yaw dynamics and may result in vibration during the flight. Both processor-in-loop （PIL） simulations and in-lake tests are presented to validate our steering control performance.

关键词： Autonomous underwater glider (AUG) Online system identification Steering control Adaptive control Optimalcontrol Energy saving control Processor-in-loop (PIL)

A Real-Time Multi-Stage Architecture for Pose Estimation of Zebrafish Head with Convolutional Neural Networks

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Journal of Computer Science & Technology 2021年第2期36卷 434-444页

作者： Zhang-Jin Huang Xiang-Xiang He Fang-Jun Wang qing shen School of Computer Science and Technology University of Science and Technology of ChinaHefei 230027China School of Data Science University of Science and Technology of ChinaHefei 230027China Anhui Province Key Laboratory of Software in Computing and Communication Hefei 230027China

In order to conduct optical neurophysiology experiments on a freely swimming zebrafish,it is essential to quantify the zebrafish head to determine exact lighting *** efficiently quantify a zebrafish head's behaviors with limited resources,we propose a real-time multi-stage architecture based on convolutional neural networks for pose estimation of the zebrafish head on *** stage is implemented with a small neural ***,a light-weight object detector named Micro-YOLO is used to detect a coarse region of the zebrafish head in the first *** the second stage,a tiny bounding box refinement network is devised to produce a high-quality bounding box around the zebrafish ***,a small pose estimation network named tiny-hourglass is designed to detect keypoints in the zebrafish *** experimental results show that using Micro-YOLO combined with RegressNet to predict the zebrafish head region is not only more accurate but also much faster than Faster R-CNN which is the representative of two-stage *** with DeepLabCut,a state-of-the-art method to estimate poses for user-defined body parts,our multi-stage architecture can achieve a higher accuracy,and runs 19x faster than it on CPUs.

关键词： convolutional neural network pose estimation real-time zebrafish

Collective Interaction of Vortices in Two-Dimensional Shear Layers

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Chinese Physics Letters 2012年第5期29卷 169-172页

作者： YANG Wu-Bing shen qing WANG Qiang China Academy of Aerospace Aerodynamics Beijing 100074

A phenomenological diagram is presented to explain the interaction between a fundamental wave and its subharmonic wave in 2D shear layers based on linear stability *** diagrams indicate that there are only four classes of subharmonic interactions,which are symmetric collective interaction,the first class of asymmetric collective interaction,the second class of collective interaction and *** of them can be determined uniquely by a couple of parameters m and p,where m is the ratio of wavenumber and p is a parameter of phase difference between the fundamental wave and its subharmonic *** each class of subharmonic interactions,a couple of parameters m and p have been deduced from the phenomenological *** think that they are significant for accurate flow control of shear layers.

关键词： theory. wave. collective

Cryo-ET bridges the gap between cell biology and structural biophysics

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Chinese Physics B 2018年第6期27卷 62-71页

作者： Xiao-Fang Cheng Rui Wang qing-Tao shen iHuman Institute ShanghaiTech University Shanghai 20121 O China Laboratory for Marine Biology and Biotechnology Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China School of Life Science and Technology ShanghaiTech University Shanghai 201210 China

Cryo-electron tomography（cryo-ET） is a cutting-edge technology providing three-dimensional in situ ultra-structural information of macromolecular machineries, organelles, and eukaryotic cells in their native environment at an unprecedented level of detail. Cryo-ET enables the direct observation of dynamic macromolecular architectures of bio-samples in their naturally occurring physiological state, without any harmful artifacts introduced by heavy metal staining, dehydration, and chemical fixation, which occur in traditional transmission electron microscopy. Over decades, cryo-ET has been providing insights into numerous aspects of cellular biology by revealing the pristinely preserved ultra-structures of different cellular components comprising the crowded and complex environment of the cell, thus, bridging the gap between cellular biology and structural biophysics. In this paper, we review the fundamentals of this technique, its recent advances in optics, detection devices, and computational algorithms. The enhancement of our understanding of structural cellular biology by combining these improvements, when integrated with other methods, such as cryo-focused ion beam milling,correlative light and electron microscopy, is discussed via a few examples from research groups worldwide. We also believe that cryo-ET applications in cell biology continue to provide fundamental insights into the field, revolutionizing structural biology itself.

关键词： sub-tomogram averaging segmentation direct detection phase plate

Dynamical effects of spin-dependent interactions in low- and intermediate-energy heavy-ion reactions

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Frontiers of physics 2015年第6期10卷 7-22页

作者： Jun Xu Bao-An Li Wen-qing shen Yin Xia Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Kavli Institute for Theoretical Physics China Chinese Academy of Sciences Beijing 100190 China Department of Physics and Astronomy Texas A&M University Commerce Commerce TX 75429-3011 USA University of Chinese Academy of Sciences Beijing 100049 China

It is well known that noncentral nuclear forces, such as the spin-orbital coupling and the tensor force, play important roles in understanding many interesting features of nuclear structures. However, their dynamical effects in nuclear reactions are poorly known because only the spin-averaged observables are normally studied both experimentally and theoretically. Realizing that spin-sensitive observables in nuclear reactions may convey useful information about the in-medium properties of noncentral nuclear interactions, besides earlier studies using the time-dependent Hartree-Fock approach to understand the effects of spin-orbital coupling on the threshold energy and spin polarization in fusion reactions, some efforts have been made recently to explore the dynamical effects of noncentral nuclear forces in intermediate-energy heavy-ion collisions using transport models. The focus of these studies has been on investigating signatures of the density and isospin dependence of the form factor in the spin-dependent single-nucleon potential. Interestingly, some useful probes were identified in the model studies but so far there are still no data to compare with. In this brief review, we summarize the main physics motivations as well as the recent progress in understanding the spin dynamics and identifying spin-sensitive observables in heavy-ion reactions at intermediate energies. We hope the interesting, important, and new physics potentials identified in the spin dynamics of heavy-ion collisions will stimulate more experimental work in this direction.

关键词： heavy-ion collisions transport model spin-orbit interaction tensor force polarization

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毛竹入侵杉木林对土壤真菌群落多样性的影响

中国土壤与肥料 2024年第2期 105-110页

作者：彭辉陈焕伟李求洁沈庆华周红敏百山祖国家公园龙泉保护中心浙江龙泉323700 龙泉市林业科学研究院浙江龙泉323700 龙泉市林业局浙江龙泉323700

为揭示凤阳山毛竹入侵杉木林后土壤真菌群落结构组成和多样性的变化,采用Illumina Miseq测序技术,分析杉木纯林、毛竹纯林及毛竹入侵后的杉木林真菌群落结构特征。结果表明:3种林型的土壤真菌类群为26门60纲113属415 OTU,子囊菌门和担... 详细信息

为揭示凤阳山毛竹入侵杉木林后土壤真菌群落结构组成和多样性的变化,采用Illumina Miseq测序技术,分析杉木纯林、毛竹纯林及毛竹入侵后的杉木林真菌群落结构特征。结果表明:3种林型的土壤真菌类群为26门60纲113属415 OTU,子囊菌门和担子菌门是绝对优势的两个菌门。两者的丰度占真菌总量80.80%~83.92%,在3种林型间均不存在显著差异。识别出的1%以上的优势菌纲有8个,为古根菌纲、伞菌纲、粪壳菌纲、锤舌菌纲、银耳纲、球囊菌纲、散囊菌纲和酵母菌纲。古根菌纲和伞菌纲占真菌总量的50.82%~75.40%。古根菌纲在毛杉混交林的相对丰度显著高于毛竹纯林(P<0.05),与杉木纯林无显著差异。Archaeorhizomyces为优势菌属(20.07%~51.51%)且在毛杉混交林中最高、在毛竹纯林最低,毛杉混交林中全氮、碱解氮和速效钾含量均显著低于杉木纯林和毛竹纯林。土壤真菌优势菌属水平丰度与土壤环境因子的斯皮尔曼相关性分析表明,全磷与Meliniomyces、毛壳菌属、Hodophilus、瓶霉属、Heterocephalacria呈显著正相关(P<0.05),与Wickerhamomyces呈极显著正相关(P<0.01)。毛竹入侵杉木林后土壤理化性质变化显著,全磷、有效磷、pH、速效钾和碳磷比是影响土壤真菌群落结构的主要环境因子,研究结果可为控制毛竹扩张,维护生态稳定和多样性提供科学依据。

关键词：真菌群落毛竹入侵杉木林高通量测序

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