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accuracy analysis in CH4MODwetland in the simulation of CH4 emissions from Chinese wetlands

Advances in Climate Change Research 2020年第1期11卷 52-59页

作者： ZHANG Qing LI Ting-Ting ZHANG Qiang WANG Guo-Cheng YU Li-Jun GUO Bin HAN Peng-Fei LAPC Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519000China Beijing Climate Center China Meteorological AdministrationBeijing100081China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan ProvinceChengdu610072China Aba Prefecture Meteorological Station Maerkang624000China LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China

Process-based models have been widely used to simulate the CH4 budget in natural wetlands,but there are still large uncenainties in ihe simulation *** analysis of process-based models is important to evaluate the reliability of model estimates for different *** this study,we analyzed the three sources of the model bias from a process-based model(CH4MODwetland)when simulating CH4 emissions from different wetland sites and types in *** a national scale,the root-mean-square error(RMSE)decreased from 70.6% at daily scale to 27.1% at annual/seasonal *** a national scale,more than 90% of the model errors were from random *** most of the sites random error contributed more than 60% to the model errors,except the Guangzhou,Haikou,Wuliangsu lake and Yancheng Estuary sites,which showed lower RMSE *** model simulated higher RMSE at the tidal marsh *** model had capability to simulate the daily and annual/seasonal CH4 emissions from all wetland types(model efficiency>0),and performed better for coastal wetlands than peatlands and marshes,with model efficiency values of 0.75 and 0.99,*** applied the model at annual/seasonal scale for peatlands,marshes,and coastal wetlands,the RMSE decreased a *** study indicated that CH4MODwetland is more accurate at annual/seasonal scale than daily scale for different wetland types across *** non-stochastic portion of CH4 emissions from peatlands,marshes and coastal wetlands can be well predicted by the model.

关键词： CH4MODwetland CH4 China Wetland accuracy analysis Simulation

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accuracy analysis for 6-DOF PKM with Sobol Sequence Based Quasi Monte Carlo Method

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Journal of Harbin Institute of Technology(New Series) 2015年第5期22卷 1-8页

作者： Jianguang Li Jian Ding Lijie Guo Yingxue Yao Zhaohong Yi Huaijing Jing Honggen Fang School of Mechatronics Engineering Harbin Institute of Technology Shanghai Aerospace Equipments Manufacturer

To improve the precisions of pose error analysis for 6-dof parallel kinematic mechanism( PKM)during assembly quality control,a Sobol sequence based on Quasi Monte Carlo( QMC) method is introduced and implemented in pose accuracy analysis for the PKM in this paper. The Sobol sequence based on Quasi Monte Carlo with the regularity and uniformity of samples in high dimensions,can prevail traditional Monte Carlo method with up to 98. 59% and 98. 25% enhancement for computational precision of pose error *** a PKM tolerance design system integrating this method is developed and with it pose error distributions of the PKM within a prescribed workspace are finally obtained and analyzed.

关键词： accuracy analysis quasi monte carlo(QMC) sobol sequence parallel kinematic mechanism(PKM)

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accuracy analysis of gradient reconstruction on isotropic unstructured meshes and its effects on inviscid flow simulation

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Advances in Aerodynamics 2019年第1期1卷 348-378页

作者： Nianhua Wang Ming Li Rong Ma Laiping Zhang State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

The accuracy of gradient reconstruction methods on unstructured meshes is analyzed both mathematically and *** derivations reveal that,for gradient reconstruction based on the Green-Gauss theorem(the GG methods),if the summation of first-and-lower-order terms does not counterbalance in the discretized integral process,which rarely occurs,second-order accurate approximation of face midpoint value is necessary to produce at least first-order accurate ***,gradient reconstruction based on the least-squares approach(the LSQ methods)is at least first-order on arbitrary unstructured *** are performed on typical isotropic grid stencils by analyzing the relationship between the discretization error of gradient reconstruction and the discretization error of the face midpoint value approximation of a given analytic ***,the numerical accuracy of gradient reconstruction methods is examined with grid convergence study on typical isotropic *** verify the phenomenon of accuracy degradation for the GG methods when the face midpoint value condition is not *** LSQ methods are proved to be at least first-order on all tested isotropic *** study gradient accuracy effects on inviscid flow simulation,solution errors are quantified using the Method of Manufactured Solutions(MMS)which was validated before adoption by comparing with an exact solution case,i.e.,the 2-dimensional(2D)inviscid isentropic *** results demonstrate that the order of accuracy(OOA)of gradient reconstruction is crucial in determining the OOA of numerical *** accuracy deteriorates seriously if gradient reconstruction does not reach first-order.

关键词： Finite volume discretization Unstructured grids Gradient reconstruction accuracy analysis The method of manufactured solutions Grid convergence study

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Design and accuracy analysis of a Metamorphic CNC Flame Cutting Machine for Ship Manufacturing

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 930-943页

作者： HU Shenghai ZHANG Manhui ZHANG Baoping CHEN Xi YU Wei College of Mechanical and Electrical Engineering Harbin Engineering University

The current research of processing large size fabrication holes on complex spatial curved surface mainly focuses on the CNC flame cutting machines design for ship hull of ship manufacturing. However, the existing machines cannot meet the continuous cutting requirements with variable pass conditions through their fixed configuration, and cannot realize high-precision processing as the accuracy theory is not studied adequately. This paper deals with structure design and accuracy prediction technology of novel machine tools for solving the problem of continuous and high-precision cutting. The needed variable trajectory and variable pose kinematic characteristics of non-contact cutting tool are figured out and a metamorphic CNC flame cutting machine designed through metamorphic principle is presented. To analyze kinematic accuracy of the machine, models of joint clearances, manufacturing tolerances and errors in the input variables and error models considering the combined effects are derived based on screw theory after establishing ideal kinematic models. Numerical simulations, processing experiment and trajectory tracking experiment are conducted relative to an eccentric hole with bevels on cylindrical surface respectively. The results of cutting pass contour and kinematic error interval which the position error is from -0.975 mm to ＋0.628 mm and orientation error is from -0.01 rad to ＋0.01 rad indicate that the developed machine can complete cutting process continuously and effectively, and the established kinematic error models are effective although the interval is within a ＇large＇ range. It also shows the matching property between metamorphic principle and variable working tasks, and the mapping correlation between original designing parameters and kinematic errors of machines. This research develops a metamorphic CNC flame cutting machine and establishes kinematic error models for accuracy analysis of machine tools.

关键词： CNC cutting machine metamorphic principle accuracy analysis screw theory error model

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Workspace and accuracy analysis on a Novel 6‑UCU Bone‑attached Parallel Manipulator

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 148-160页

作者： Kaijie Dong Duanling Li Xingyu Xue Chang Xu Haowei Wang Xianming Gao School of Automation Beijing University of Posts and TelecommunicationsBeijing 100876China th Research Institute of China Electronics Technology Group Corporation Hefei 340100China Beijing Institute of Spacecraft System Engineering China Academy of Space TechnologyBeijing 100094China College of Mechanical and Electrical Engineering Shaanxi University of Science and TechnologyXi’an 712000China

With the increasingly more extensive application of the medical surgical robot in the clinic,higher requirements have been put forward for medical *** bone-attached robot,a popular orthopedic robot in recent years,has a tendency of miniaturization and ***,a bone-attached parallel manipulator(PM)based on 6-UCU(universalcylindrical-universal)configuration is proposed,which is characterized by small volume,compact structure,high precision and six-dimensional force *** optimize the structure and make it more compact,the workspace of the 6-UCU PM is analyzed based on the analysis of three kinds of constraint,and workspace model is established through spherical coordinate search *** study also analyzes the influence of structural parameters on workspace,which may contribute to improving the efficiency of design and ensuring small-sized robots possess relatively large ***,to improve the motion accuracy,an error modeling method is developed based on the structure of 6-UCU *** to this established error model,the output pose error curves are drawn using MATLAB software when the structure parameters change,and the influence of the structure and pose parameters change on the output pose error of PMs is *** proposed research provides the instruction to design and analysis of small PMs such as bone-attached robots.

关键词： Medical robot Bone-attached robot Parallel manipulator Workspace analysis accuracy analysis

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Parameter accuracy analysis of weak-value amplification process in the presence of noise

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Chinese Physics B 2021年第6期30卷 385-389页

作者： Jiangdong Qiu Zhaoxue Li Linguo Xie Lan Luo Yu He Changliang Ren Zhiyou Zhang Jinglei Du College of Physics Sichuan UniversityChengdu 610064China Key Laboratory of Photonic and Optical Detection in Civil Aviation and Atmospheric Lidar Institute Civil Aviation Flight University of ChinaGuanghan 618300China Center for Nanofabrication and System Integration Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China

We theoretically introduce the statistical uncertainty of photon number and phase error to discuss the precision of parameters to be measured based on weak measurements. When the photon counting scheme is used, we discuss the relative accuracy of the system in the presence of phase error by using the orthogonal and nonorthogonal pre-and postselected states, respectively. When using the measurement scheme of pointer shift, we discuss the measurement accuracy in the presence of phase error, pointer resolution, and statistical uncertainty. These results give a guide way to get the smallest relative precision and deepen our understanding about weak measurement.

关键词： weak measurement quantum measurement accuracy analysis

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Nonlinearity for a parallel kinematic machine tool and its application to interpolation accuracy analysis

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Science China(Technological Sciences) 2002年第1期45卷 97-105页

作者：汪劲松王忠华黄田 D.J.Whitehouse Department of Engineering University of WarwickCoventry CV4 7ALW Midlands UK

This paper is concerned with the kinematic nonlinearity measure of parallel kinematic machine tool (PKM), which depends upon differential geometry curvalure. The nonlinearity can be described by the curve of the solution locus and the equal interval input of joints mapping into inequable interval output of the end-effectors. Such curing and inequation can be measured by BW curvature. So the curvature can measure the nonlinearity of PKM indirectly. Then the distribution of BW curvature in the local area and the whole workspace are also discussed. An example of application to the interpolation accuracy analysis of PKM is given to illustrate the effectiveness of this approach.

关键词： parallel kinematic machine tool nonlinearity measure curvature interpolation accuracy analysis

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PASSIVE LOCATION AND accuracy analysis USING TDOA INFORMATION OF MULTI-STATIONS

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Chinese Journal of Aeronautics 1998年第1期11卷 38-44页

作者：杨林周一宇孙仲康 Institute of Electronic Engineering Natl. Univ. of Defense Technology Changsha Hunan 410073 China

ＰＡＳＳＩＶＥＬＯＣＡＴＩＯＮＡＮＤＡＣＣＵＲＡＣＹＡＮＡＬＹＳＩＳＵＳＩＮＧＴＤＯＡＩＮＦＯＲＭＡＴＩＯＮＯＦＭＵＬＴＩ┐ＳＴＡＴＩＯＮＳＹａｎｇＬｉｎ（杨林），ＺｈｏｕＹｉｙｕ（周一宇），ＳｕｎＺｈｏｎｇｋａｎｇ... 详细信息

ＰＡＳＳＩＶＥＬＯＣＡＴＩＯＮＡＮＤＡＣＣＵＲＡＣＹＡＮＡＬＹＳＩＳＵＳＩＮＧＴＤＯＡＩＮＦＯＲＭＡＴＩＯＮＯＦＭＵＬＴＩ┐ＳＴＡＴＩＯＮＳＹａｎｇＬｉｎ（杨林），ＺｈｏｕＹｉｙｕ（周一宇），ＳｕｎＺｈｏｎｇｋａｎｇ（孙仲康）（Ｉｎｓｔｉｔｕｔｅｏｆ...

关键词： positioning devices locates system passive location TDOA accuracy analysis GDOP

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accuracy analysis of BDS experiment satellite broadcast ephemeris

Accuracy analysis of BDS experiment satellite broadcast ephe...

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第九届中国卫星导航学术年会

作者： Ya Mao Qianxin Wang Chao Hu Yilei He School of Environment Science & Spatial Informatics China University of Mining and Technology

Currently,five BDS-3 experiment satellites are transmitting both BDS-2 signals and new signals for *** are equipped with high-precision rubidium or/and passive hydrogen maser *** view of the inconsistency of BDS-3 experiment satellites signals received by i GMAS and MGEX network,the experiment to determine BDS-3 orbits is carried out by the step by step method through one *** order to improve the efficiency and avoid the inverse anomalies caused by too large matrix dimension in the inversion process,the normal equation matrix is decomposed by *** this paper,the internal accuracy of BDS-3(C31/C32/C33/C34) satellites orbit and clock offset is evaluated by overlapping arcs,and the average values in one year are 36.5 cm/38.4 cm/44.1 cm/48.8 cm and 2.27 ns/2.40 ns/1.88 ns/1.87 ns *** addition,satellite laser ranging(SLR),as an important external inspection tool,has been widely used in satellite orbit accuracy *** SLR to evaluate the orbit outside accuracy,and the average values of one year is 51.4 cm/40.2 cm/62.9 cm/82 ***,the precision of BDS-3 satellites broadcast-clock offset and broadcast-orbit is evaluated by BDS-3 precise ephemeris,and the SLR observation data is taken as the external inspection tool to evaluate the *** results show that the BDS-3 experiment satellite broadcast-clock accuracy is better than 40 ns,and the broadcast-orbit accuracy is about 1 m.

关键词： SLR check BDS-3 broadcast ephemeris step-by-step method accuracy analysis

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The accuracy analysis of Gyro-stabilization Platform Affected by Mechanical Assembling Error

The Accuracy Analysis of Gyro-stabilization Platform Affecte...

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第四届国际机械工程与力学会议

作者： Yan LI Yong ZHANG Naval Aeronautical Engineering Academy Qingdao Branch

This paper analyses the principle of assembling error affecting the stabilization accuracy of the platform with the multi-axis mechanism for tracking, measurement and aiming based on gyro-stabilization, and simulates the effect. It develops the mathematical model showing the kinematics effect of assembling error by PIOGRAM method, on the basis of which it simulates the practical two-axis platform and research each error’s impact on stabilization precision. Furthermore the paper studies the effect principle of assembling errors. The research may work for reference on the accuracy allocation during the designing of scenario.

关键词： Gyro-stabilization Mechanism Assembling error PIOGRAM method accuracy analysis

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