检索结果-南通市图书馆

Enhancing the terrain adaptability of a multirobot cooperative transportation system via novel connectors and optimized cooperative strategies

引用

Frontiers of Mechanical Engineering 2023年第3期18卷 79-97页

作者： Quan Liu Zhao GONG Zhenguo NIE Xin-Jun liu State Key Laboratory of Tribology in Advanced Equipment&Institute of Manufacturing Engineering Department of Mechanical EngineeringTsinghuaUniversityBeijing 100084China Beijing Key Laboratory of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua UniversityBejing 100084China

Given limited terrain adaptability,most existing multirobot cooperative transportation systems(MRCTSs)mainly work on flat pavements,restricting their outdoor applications.The connectors'finite deformation capability and the control strategies'limitations are primarily responsible for this phenomenon.This study proposes a novel MRCTS based on tracked mobile robots(TMRs)to improve terrain adaptability and expand the application scenarios of MRCTSs.In structure design,we develop a novel 6-degree-of-freedom passive adaptive connector to link multiple TMRs and the transported object(the communal payload).In addition,the connector is set with sensors to measure the position and orientation of the robot with respect to the object for feedback control.In the control strategy,we present a virtual leader-physical follower collaborative paradigm.The leader robot is imaginary to describe the movement of the entire system and manage the follower robots.All the TMRs in the system act as follower robots to transport the object cooperatively.Having divided the whole control structure into the leader robot level and the follower robot level,we convert the motion control of the two kinds of robots to trajectory tracking control problems and propose a novel double closed-loop kinematics control framework.Furthermore,a control law satisfying saturation constraints is derived to ensure transportation stability.An adaptive control algorithm processes the wheelbase uncertainty of the TMR.Finally,we develop a prototype of the TMR-based MRCTS for experiments.In the trajectory tracking experiment,the developed MRCTS with the proposed control scheme can converge to the reference trajectory in the presence of initial tracking errors in a finite time.In the outdoor experiment,the proposed MRCTS consisting of four TMRs can successfully transport a payload weighing 60 kg on an uneven road with the single TMR's maximum load limited to 15 kg.The experimental results demonstrate the effectiveness of the structural design and control strategies of

关键词： multirobot system cooperative transportation terain adaptability trajectory tracking collaborative paradigm uneven road

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Mechanism of ethanol/water reverse separation through a functional graphene membrane:a molecular simulation investigation

引用

Frontiers of Chemical Science and Engineering 2023年第3期17卷 347-357页

作者： Quan Liu Xian Wang Yanan Guo Gongping liu Kai-Ge Zhou School of Chemical Engineering Analytical and Testing CenterAnhui University of Science and TechnologyHuainan 232001China State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Reverse-selective membranes have attracted considerable interest for bioethanol production.However,to date,the reverse-separation performance of ethanol/water is poor and the separation mechanism is unclear.Graphene-based membranes with tunable apertures and functional groups have shown substantial potential for use in molecular separation.Using molecular dynamics simulations,for the first time,we reveal twoway selectivity in ethanol/water separation through functional graphene membranes.Pristine graphene(PG)exhibits reverse-selective behavior with higher ethanol fluxes than water,resulting from the preferential adsorption for ethanol.Color flow mappings show that this ethanol-permselective process is initiated by the presence of ethanol-enriched and water-barren pores;this has not been reported in previous studies.In contrast,water molecules are preferred for hydroxylated graphene membranes because of the synergistic effects of molecular sieving and functional-group attraction.A simulation of the operando condition shows that the PG membrane with an aperture size of 3.8Åachieves good separation performance,with an ethanol/water separation factor of 34 and a flux value of 69.3 kg∙m‒2∙h‒1∙bar‒1.This study provides new insights into the reverse-selective mechanism of porous graphene membranes and a new avenue for efficient biofuel production.

关键词： reverse separation graphene membrane ethanol/water separation molecular simulation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The breaking of spin symmetry in the single-particle resonances in deformed nuclei

引用

Nuclear Science and Techniques 2024年第3期35卷 237-245页

作者： Zhen-Yu Zheng Shou-Wan Chen Quan Liu School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

The exploration of spin symmetry (SS) in nuclear physics has been instrumental in identifying atomic nucleus structures.In this study,we solve the Dirac equation from the relativistic mean field (RMF) in complex momentum representation.We investigated SS and its breaking in single-particle resonant states within deformed nuclei,with a focus on the illustrative nucleus168Er.This was the initial discovery of a resonant spin doublet in a deformed nucleus,with the expectation of the SS approaching the continuum threshold.With increasing single-particle energy,the splitting of the resonant spin doublets widened significantly.This escalating splitting implies diminishing adherence to the SS,indicating a departure from the expected behavior as the energy levels increase.We also analyzed the width of the resonant states,showing that lower orbital angular momentum resonances possess shorter decay times and that SS is preserved within broad resonant doublets,as opposed to narrow resonant doublets.Comparing the radial density of the upper components for the bound-state and resonant-state doublets,it becomes evident that while SS is well-preserved in the bound states,it deteriorates in the resonant states.The impact of nuclear deformation (β_(2)) on SS was examined,demonstrating that an increase in β_(2) resulted in higher energy and width splitting in the resonant spin doublets,which is attributed to increased component mixing.Furthermore,the sensitivity of spin doublets to various potential parameters such as surface diffuseness (a),radius (R),and depth (Σ0) is discussed,emphasizing the role of these parameters in SS.This study provides valuable insights into the behavior of spin doublets in deformed nuclei and their interplay with the nuclear structure,thereby advancing our understanding of SS in the resonance state.

关键词： Spin symmetry Resonant states Deformed nuclei Complex-momentum representation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hybrid Navigation System Based Autonomous Positioning and Path Planning for Mobile Robots

引用

Chinese Journal of Mechanical Engineering 2022年第5期35卷 219-231页

作者： Shuzhan Shentu Zhao Gong Xin‑Jun liu Quan Liu Fugui Xie The State Key Laboratory of Tribology Department of Mechanical Engineering(DME)Tsinghua UniversityBeijing 100084China Beijing Key Lab of Precision/Ultra‑precision Manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China

Positioning and navigation technology is a new trend of research in mobile robot area.Existing researches focus on the indoor industrial problems,while many application fields are in the outdoor environment,which put forward higher requirements for sensor selection and navigation scheme.In this paper,a complete hybrid navigation system for a class of mobile robots with load tasks and docking tasks is presented.The work can realize large-range autonomous positioning and path planning for mobile robots in unstructured scenarios.The autonomous positioning is achieved by adopting suitable guidance methods to meet different application requirements and accuracy requirements in conditions of different distances.Based on the Bezier curve,a path planning scheme is proposed and a motion controller is designed to make the mobile robot follow the target path.The Kalman filter is established to process the guidance signals and control outputs of the motion controller.Finally,the autonomous positioning and docking experiment are carried out.The results of the research verify the effectiveness of the hybrid navigation,which can be used in autonomous warehousing logistics and multi-mobile robot system.

关键词： Hybrid navigation system Positioning and path planning The Kalman filter Autonomous docking

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

One year results of presbyLASIK using hybrid bi-aspheric micro-monovision ablation profile in correction of presbyopia and myopic astigmatism

引用

International Journal of Ophthalmology(English edition) 2020年第2期13卷 271-277页

作者： Fang liu Ting Zhang Quan Liu State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CentreSun Yat-sen UniversityGuangzhou 510060Guangdong ProvinceChina

●AIM:To analyze one year clinical outcomes and subjective rating of hybrid bi-aspheric multifocal central presbyLASIK with micro-monovision for correction of presbyopia and myopic astigmatism.●METHODS:Seventy-four eyes of 37 patients consecutively treated with presbyLASIK were assessed.The mean age of the patients was 43.8±3.0 y with a mean spherical equivalent refraction of-5.21±1.87 diopters(D)and mean astigmatism of-0.82±0.64 D.Visual acuity,manifest refraction,contrast sensitivity,aberrometry and patients’subjective rating were evaluated pre-and postoperatively.●RESULTS:At 1 y postoperatively(68 eyes of 34 patients),the mean spherical equivalent(SE)refraction in distance eyes was 0.06±0.05 D,whereas the achieved SE in near eyes was-0.83±0.05 D.Ninety-nine percent of eyes were within±0.50 D of target correction of SE.The binocular mean uncorrected distance visual acuity(UDVA)was 0.00±0.18 logMAR(20/20).Sixty-four percent of patients achieved 0.0 logMAR(20/20)or better of UDVA and 0.1 logRAD or better of UNVA as well.There was a binocularly loss of one line CDVA after surgery for only one patient(3%,1/34)and no patient lost 2 lines.The changes in binocular contrast sensitivity(CS)in all test conditions were not significant at any frequency after surgery.The changes of entire eye total higher order aberrations(tHOA)and spherical aberrations(SA)significantly higher in near eyes than in distance eyes.The overall satisfaction score for surgery was 93±8.●CONCLUSION:The hybrid bi-aspheric multifocal central presby LASIK with micro-monovision appears to be an efficacious option for myopic presbyopes.One year postoperative outcomes in a relatively young presbyopia population indicate improvements in both far and near vision with high satisfaction.

关键词： presbyLASIK presbyopia monovison myopia

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Bi-doped carbon quantum dots functionalized liposomes with fluorescence visualization imaging for tumor diagnosis and treatment

引用

Chinese Chemical Letters 2024年第4期35卷 414-419页

作者： Peide Zhu Yangjia liu Yaoyao Tang Siqi Zhu Xinyang liu Lei Yin Quan Liu Zhiqiang Yu quan Xu Dixian Luo Juncheng Wang State Key Laboratory of Heavy Oil Processing China University of Petroleum-BeijingBeijing 102249China Department of Laboratory Medicine Dongguan Institute of Clinical Cancer ResearchAffiliated Dongguan HospitalSouthern Medical UniversityDongguan 523058China Department of Laboratory Medicine Huazhong University of Science and Technology Union Shenzhen Hospital(Nanshan Hospital)Shenzhen 518052China Institute of Stomatology First Medical CenterChinese PLA General HospitalBeijing 100853China

Liposomes are one of the significant classes of antitumor nanomaterials and the most successful nanomedicine drugs in clinical translation. However, it is difficult to accurately reveal liposome delivery modes and drug release rates at different p H values to assess the biodistribution and drug delivery pathways in vivo. Here, we established a strategy to integrate Bi-doped carbon quantum dots(CQDs)with liposomes to produce fluorescence visualization and therapeutic effects, namely lipo/Bi-doped CQDs.Lipo/Bi-doped CQDs show good water solubility and physicochemical properties, which can be used for in vitro labeling of colon cancer(CT26) cells and in vivo imaging localization tracking tumors for monitoring. Simultaneously, thanks to the excellent p H sensitivity and ion doping characteristic of Bi-doped CQDs, lipo/Bi-doped CQDs can be used to reveal the drug release rate of liposomes at different p H values and exhibit potential effects in vivo antitumor therapy.

关键词： Bi-doped CQDs Lipo/Bi-doped CQDs pH sensitivity In vitro/in vivo imaging Diagnosis and treatment integration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Role of platelet-derived extracellular vesicles in traumatic brain injury-induced coagulopathy and inflammation

引用

Neural Regeneration Research 2022年第10期17卷 2102-2107页

作者： Liang liu quan-Jun Deng Department of Neurosurgery Tianjin Institute of NeurologyTianjin Medical University General HospitalTianjinChina

Extracellular vesicles are composed of fragments of exfoliated plasma membrane,organelles or nuclei and are released after cell activation,apoptosis or destruction.Platelet-derived extracellular vesicles are the most abundant type of extracellular vesicle in the blood of patients with traumatic brain injury.Accumulated laboratory and clinical evidence shows that platelet-derived extracellular vesicles play an important role in coagulopathy and inflammation after traumatic brain injury.This review discusses the recent progress of research on platelet-derived extracellular vesicles in coagulopathy and inflammation and the potential of platelet-derived extracellular vesicles as therapeutic targets for traumatic brain injury.

关键词： angiogenesis clotting factors coagulopathy delivery inflammation platelet-derived extracellular vesicles review target traumatic brain injury

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

网络平台的公共性与法律治理--中央财经大学刘权教授讲座实录

引用

研究生法学 2023年第1期38卷 22-31页

作者：刘权祖昊中央财经大学法学院中央财经大学数字经济与法治研究中心《财经法学》中国政法大学光明新闻传播学院《法大研究生》

祖昊:各位老师同学们,晚上好。今天的主题是网络平台的公共性与法律治理。这是一个涉及法学、传播和平台经济等领域的热点问题。我们都知道,互联网平台在自上而下增长的模式下,展现出了强大的公共性,但也面临着平台垄断和算法隔离等挑... 详细信息

祖昊:各位老师同学们,晚上好。今天的主题是网络平台的公共性与法律治理。这是一个涉及法学、传播和平台经济等领域的热点问题。我们都知道,互联网平台在自上而下增长的模式下,展现出了强大的公共性,但也面临着平台垄断和算法隔离等挑战如何从法律角度理解和治理。这些问题需要深入的探讨和研究。今天,我们有幸邀请到了中央财经大学的刘权老师为我们分享他的见解和思考。

关键词：中央财经大学网络平台互联网平台自上而下公共性老师热点问题

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hierarchical Reinforcement Learning With Automatic Sub-Goal Identification

引用

IEEE/CAA Journal of Automatica Sinica 2021年第10期8卷 1686-1696页

作者： Chenghao liu Fei Zhu Quan Liu Yuchen Fu School of Computer Science and Technology Soochow UniversitySuzhou 215006China School of Computer Science and Engineering Changshu Institute of TechnologyChangshu 215500China

In reinforcement learning an agent may explore ineffectively when dealing with sparse reward tasks where finding a reward point is difficult.To solve the problem,we propose an algorithm called hierarchical deep reinforcement learning with automatic sub-goal identification via computer vision(HADS)which takes advantage of hierarchical reinforcement learning to alleviate the sparse reward problem and improve efficiency of exploration by utilizing a sub-goal mechanism.HADS uses a computer vision method to identify sub-goals automatically for hierarchical deep reinforcement learning.Due to the fact that not all sub-goal points are reachable,a mechanism is proposed to remove unreachable sub-goal points so as to further improve the performance of the algorithm.HADS involves contour recognition to identify sub-goals from the state image where some salient states in the state image may be recognized as sub-goals,while those that are not will be removed based on prior knowledge.Our experiments verified the effect of the algorithm.

关键词： Hierarchical control hierarchical reinforcement learning option sparse reward sub-goal

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical study on Janus graphene oxide membrane for water transport

引用

Frontiers of Chemical Science and Engineering 2021年第4期15卷 913-921页

作者： Quan Liu Mingqiang Chen Yangyang Mao Gongping liu Analytical and Testing Center Anhui University of Science and TechnologyHuainan 232001China State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China

Graphene oxide(GO)membranes have received considerable attention owing to their outstanding water-permeation properties;however,the effect of the membrane’s microstructures(such as the distribution of oxidized and pristine regions)on the transport mechanism remains unclear.In this study,we performed molecular simulations to explore the permeation of a water-ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces.The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules.Consequently,using the optimized Janus GO membrane,infinite water selectivity and outstanding water flux(-40.9 kg·m^(-2) h^(-1))were achieved.This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water-ethanol separation.

关键词： graphene oxide membrane molecular dynamics simulation water permeation water-ethanol separation oxidized and pristine regions

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：