检索结果-南通市图书馆

Computer-based Creativity Enhanced Conceptual Design Model for Non-routine Design of Mechanical Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2014年第6期27卷 1083-1098页

作者： li yutong WANG Yuxin DUFFY Alex H B Department of Mechanical & Electrical Engineering China University of Petroleum Design Manufacture and Engineering ManagementUniversity of Strathclyde

Computer-based conceptual design for routine design has made great strides, yet non-routine design has not been given due attention, and it is still poorly automated. Considering that the function-behavior-structure（FBS） model is widely used for modeling the conceptual design process, a computer-based creativity enhanced conceptual design model（CECD） for non-routine design of mechanical systems is presented. In the model, the leaf functions in the FBS model are decomposed into and represented with fine-grain basic operation actions（BOA）, and the corresponding BOA set in the function domain is then constructed. Choosing building blocks from the database, and expressing their multiple functions with BOAs, the BOA set in the structure domain is formed. Through rule-based dynamic partition of the BOA set in the function domain, many variants of regenerated functional schemes are generated. For enhancing the capability to introduce new design variables into the conceptual design process, and dig out more innovative physical structure schemes, the indirect function-structure matching strategy based on reconstructing the combined structure schemes is adopted. By adjusting the tightness of the partition rules and the granularity of the divided BOA subsets, and making full use of the main function and secondary functions of each basic structure in the process of reconstructing of the physical structures, new design variables and variants are introduced into the physical structure scheme reconstructing process, and a great number of simpler physical structure schemes to accomplish the overall function organically are figured out. The creativity enhanced conceptual design model presented has a dominant capability in introducing new deign variables in function domain and digging out simpler physical structures to accomplish the overall function, therefore it can be utilized to solve non-routine conceptual design problem.

关键词： conceptual design non-routine design creative enhance model computer-based approach mathematical expression

A novel method to avoid turning point singularities for the semi-regular hexagons Gough-Stewart parallel manipulator

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第7期51卷 897-910页

作者： WANG YuXin li yutong PAN ShuangXia College of Mechanical Engineering&Energy Zhejiang UniversityHangzhou 310027China

This paper presents a novel disturbance function method to avoid turning point singularities for the semi-regular hexagons 6-SPS Gough-Stewart manipulator. Through analysis of the configuration bifurcation characteristics of the manipulator at the type-II singular points, it is found that the type-II singularities under signal input parameter belong to turning point bifurcation. The configuration patterns for the manipulator to pass through the turning points are divided into three types: persistent, non-persistent and path configuration. Utilizing the universal unfolding approach, the configuration bifurcation characteristics under the perturbation pa- rameters applied to the extendable legs are analyzed. The investigation reveals that all configuration branches converged in the same singular point in the unperturbed system will be separated in the disturbed system. Based on this discovery, a novel method for the parallel manipulator to pass through the singular points with the desired configuration is presented. Then the disturbance functions for the manipulator to pass through the turning points with the persistent configuration and the non-persistent configuration are constructed. The method presented in this paper can be applied to avoiding the singularities in such cases where the path and orientation of the manipulator are strictly programmed.

关键词： parallel manipulator turning point singularity disturbance function

Singular Assembly Configurations and Configuration Bifurcation Characteristics of the Semi-regular Hexagons 6-6 Gough-Stewart Manipulator

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2009年第6期22卷 810-821页

作者： li yutong WANG Yuxin HUANG Zhen PAN Shuangxia Institute of Mechanical Design Zhejiang University Hangzhou 310027 China Robotic Research Center Yanshan University Qinhuangdao 066004 China

It is well known that singular configurations are inherent to parallel manipulators and have serious influences on their properties. Therefore, these singular configurations should be avoided in the design and application of mechanisms. The researches on the singularity identification and distribution have revealed the relations among the six configuration parameters at singular points. Few works have dealt with the relation between the singularity and the input parameters, as wcll as the properties of the manipulator nearby the singularity. In this paper, taking the semi-regular hexagons 6-6 Gough-Stewart manipulator （SRHGSMP） as an example, the configuration bifurcation characteristics going with the input parameters, the assembly configurations at singular points, and the reasons to cause the singularity are analyzed. The research reveals that the number and the combination of the input parameters have great influences on the complexity of the singularity and the curvature radiuses of the configuration curves. Under different number of input parameters, the dimensional-utmost singularity, line vectors correlation singularity and Jacobian matrix correlation singularity can occur individually or jointly. Choosing the adjacent input parameters, the simple singularity and the large singularity-free input parameters zones can be obtained. And selecting multiple input parameters, the self-motion regions and the singularity avoidance errors can be reduced. These new discoveries are valuable and of significance for the trajectory design, the singularity avoidance, and the self-motion control of the parallel manipulator.

关键词： parallel manipulator singular assembly configuration configuration curve

YOLO-Drone:A Scale-Aware Detector for Drone Vision

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第4期33卷 1034-1045页

作者： yutong li Miao MA Shichang liU Chao YAO Longjiang GUO School of Computer Science Shaanxi Normal University Key Laboratory of Modern Teaching Technology Ministry of Education College of Computer Science Sichuan University

Object detection is an important task in drone vision. Since the number of objects and their scales always vary greatly in the drone-captured video, small object-oriented feature becomes the bottleneck of model performance, and most existing object detectors tend to underperform in drone-vision scenes. To solve these problems, we propose a novel detector named YOLO-Drone. In the proposed detector, the backbone of YOLO is firstly replaced with ConvNeXt, which is the state-of-the-art one to extract more discriminative features. Then, a novel scale-aware attention(SAA) module is designed in detection head to solve the large disparity scale problem. A scale-sensitive loss(SSL) is also introduced to put more emphasis on object scale to enhance the discriminative ability of the proposed detector. Experimental results on the latest VisDrone 2022 test-challenge dataset(detection track) show that our detector can achieve average precision(AP) of 39.43%, which is tied with the previous state-of-the-art, meanwhile,reducing 39.8% of the computational cost.

关键词： YOLO Costs Object oriented modeling Computational modeling Detectors Feature extraction Data models

Investigation of dielectric barrier discharge plasma flow control

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第7期51卷 1064-1072页

作者： NIE ChaoQun li Gang ZHU JunQiang ZHANG Yi li yutong Key Laboratory of Advanced Energy and Power of Chinese Academy of Sciences at Institute of Engineering Thermophysics Beijing 100080China Laboratory of Optical Physics Institute of PhysicsChinese Academy of SciencesBeijing 100080China

Effects of plasma flow control are researched on the basis of plasma exciting flow experiments and numerical simulations. Turbulent model is more effective than laminar model in plasma numerical simulation as results showed. Both plasma exciting effects of acceleration and flow separation suppression are investigated through experiments carried on the flat plate and the compressor cascades. The results demonstrate that boundary layer characteristic is modified by plasma exciting. Distributions of total pressure and velocity in the wake are improved notably for 20 m/s coming velocity and the effect of plasma can still be observed while velocity is increased to 50 m/s. For low velocity flow, plasma exciting is effective in flow separation suppression.

关键词： flow control dielectric barrier discharge plasma plasma exciting compressor cascade flow separation

Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 76-80页

作者： CUI YunQian SHENG ZhengMing LU QuanMing li yutong ZHANG Jie Beijing National Laboratory of Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Scottish Universities Physics Alliance Department of Physics University of Strathclyde Key Laboratory for Laser Plasmas (Mo E) and Department of Physics and Astronomy Shanghai Jiao Tong University IFSA Collaborative Innovation Center Shanghai Jiao Tong University School of Earth and Space Sciences University of Science and Technology of China

We present the particle-in-cell(PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely(perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 Me V under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments.

关键词： particle acceleration Fermi acceleration collisionless shock lepton plasma flow

Dynamics of Land Use/Land Cover Considering Ecosystem Services for a Dense-Population Watershed Based on a Hybrid Dual-Subject Agent and Cellular Automaton Modeling Approach

在线全文

学校读者我要写书评

暂无评论

Engineering 2024年第6期37卷 182-195页

作者： yutong li Yanpeng Cai Qiang Fu Xiaodong Zhang Hang Wan Zhifeng Yang Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds Institute of Environmental and Ecological EngineeringGuangdong University of TechnologyGuangzhou 510006China School of Water Conservancy and Civil Engineering Northeast Agricultural UniversityHarbin 150030China School of Environmental Science and Engineering Shandong UniversityQingdao 266000China

Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among *** study introduced economic standards for farmers.A hybrid approach(CA-ABM)of cellular automaton(CA)and an agent-based model(ABM)was developed to effectively deal with social and land-use synergic issues to examine human–environment interactions and projections of land-use conversions for a humid basin in south *** attributes and socioeconomic data were used to analyze land use/land cover and its drivers of *** major modules of the CA-ABM are initialization,migration,assets,land suitability,and land-use change *** estimates of the factors influencing the urban land-use conversion probability were captured using parameters based on a spatial logistic regression(SLR)***,multicriteria evaluation(MCE)and Markov models were introduced to obtain empirical estimates of the factors affecting the probability of ecological land *** agent-based CA-SLR-MCE-Markov(ABCSMM)land-use conversion model was proposed to explore the impacts of policies on land-use *** model can reproduce observed land-use patterns and provide links for forest transition and urban expansion to land-use decisions and ecosystem *** results demonstrated land-use simulations under multi-policy scenarios,revealing the usefulness of the model for normative research on land-use management.

关键词： Land use/land cover Human-environment interactions Agent-based model Cellular automaton

Impact damage testing based on high-speed continuous water jet aircraft coatings

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

Chinese Journal of Aeronautics 2024年第10期37卷 249-264页

作者： Minggong SHA Ying SUN yutong li Yiming liU Gregory FEDOTENKOV Lev RABINSKIY Arseniy BABAYTSEV Yulong li School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710072China Joint International Research Laboratory of Impact Dynamics and Engineering Application Xi’an 710072China Shaanxi Impact Dynamics and Engineering Application Laboratory Xi’an 710072China NPU Yangzi River Delta Research Institute Suzhou 215400China Moscow Aviation Institute(National Research University) Moscow 125993Russia

When an aircraft passes through a rainy area at high speed,the coating on the front edge of the fuselage will be continuously eroded by raindrops,causing the coating to wear,crack or even peel *** paper uses carbon fiber T300 material as the base material,and at the different impact speeds and impact numbers,water cutting equipment was used to simulate the erosion of the coating caused by the continuous impact of water *** damage morphology of samples at different damage stages was observed by digital microscope and Scanning Electron Microscope(SEM),and the damage evolution curve was established to analyze and reveal the damage behavior and damage mechanism of rain *** results show that the degree of damage experienced an increasing trend with the increase of impact numbers and speed,until circular peel damage was formed;no damage occurred during the incubation period,and the curvature of the damage evolution curve increased significantly after the expansion period and eventually showed a stable expansion *** mechanical properties of the coating material were the main influencing factors of its rain corrosion ***,the axially symmetric unsteady contact problem of droplets impacting the surface of a solid deformable body was *** the contact area was determined based on the iterative algorithm boundary positioning method.A mathematical model and closed mathematical formula describing the unsteady interaction between a droplet and a solid deformable obstacle were proposed.

关键词： Rain erosion damage liquid-solid impact Multiple jets Composite materials Impact dynamics

Response of HD-V2 radiochromic film to argon ions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第8期30卷 282-286页

作者： Lei Cheng Zhe Zhang Guiyun liang yutong li Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences(CAS)Beijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China Songshan Lake Materials Laboratory Dongguan 523808China CAS Center for Excellence in Ultra-intense Laser Science Shanghai 201800China

A two-dimensional dose detector for ion beam is required in many high energy density physics *** a solid detector,the GAFChromic film offers a good spatial resolution and dosimetric *** an absolute dose measurement,the relative effectiveness,which represents the darkening efficiency of the film to a radiation source,needs to be taken into *** this contribution,the dose-response of HD-V2 to argon ions is presented for the first *** calibration was taken over the dose range of 65 Gy-660 Gy with 8-keV argon *** response of net optical density is from 0.01 to ***-color dose-response functions are *** relative effectiveness for the argon ion beams is about 5%,much lower than that of protons and carbon *** explain this effect,the inactivation probability based on track theory of ion bombardment is ***,a theoretical prediction of the relative effectiveness for single ion is presented,showing the dependence of the darkening efficiency on the atomic number and the incident energy of ions.

关键词： radiochromic film dosimetry ion bombardment relative effectiveness