期刊文献+
共找到230篇文章
< 1 2 12 >
每页显示 20 50 100
3-Dimensional Kinematic Comparison of Arm Movements between an Individual with NGLY1 Deficiency and a Neurotypical Individual
1
作者 Charles S. Layne Christopher A. Malaya +6 位作者 Brock Futrell Dacia Martinez Diaz Christian Alfaro Hannah E. Gustafson Subhalakshmi Chandrasekaran Rhea M. Phatak Bernhard Suter 《Case Reports in Clinical Medicine》 2024年第4期122-146,共25页
NGLY1 Deficiency is an ultra-rare autosomal recessively inherited disorder. Characteristic symptoms include among others, developmental delays, movement disorders, liver function abnormalities, seizures, and problems ... NGLY1 Deficiency is an ultra-rare autosomal recessively inherited disorder. Characteristic symptoms include among others, developmental delays, movement disorders, liver function abnormalities, seizures, and problems with tear formation. Movements are hyperkinetic and may include dysmetric, choreo-athetoid, myoclonic and dystonic movement elements. To date, there have been no quantitative reports describing arm movements of individuals with NGLY1 Deficiency. This report provides quantitative information about a series of arm movements performed by an individual with NGLY1 Deficiency and an aged-matched neurotypical participant. Three categories of arm movements were tested: 1) open ended reaches without specific end point targets;2) goal-directed reaches that included grasping an object;3) picking up small objects from a table placed in front of the participants. Arm movement kinematics were obtained with a camera-based motion analysis system and “initiation” and “maintenance” phases were identified for each movement. The combination of the two phases was labeled as a “complete” movement. Three-dimensional analysis techniques were used to quantify the movements and included hand trajectory pathlength, joint motion area, as well as hand trajectory and joint jerk cost. These techniques were required to fully characterize the movements because the NGLY1 individual was unable to perform movements only in the primary plane of progression instead producing motion across all three planes of movement. The individual with NGLY1 Deficiency was unable to pick up objects from a table or effectively complete movements requiring crossing the midline. The successfully completed movements were analyzed using the above techniques and the results of the two participants were compared statistically. Almost all comparisons revealed significant differences between the two participants, with a notable exception of the 3D initiation area as a percentage of the complete movement. The statistical tests of these measures revealed no significant differences between the two participants, possibly suggesting a common underlying motor control strategy. The 3D techniques used in this report effectively characterized arm movements of an individual with NGLY1 deficiency and can be used to provide information to evaluate the effectiveness of genetic, pharmacological, or physical rehabilitation therapies. 展开更多
关键词 NGLY1 Deficiency Developmental Disorders kinematics 3 dimensional Analyses
下载PDF
Three Dimensional Kinematics Analysis of the Independent Suspension Multibody System 被引量:2
2
作者 陈欣 林逸 +1 位作者 孙大刚 白文辉 《Journal of Beijing Institute of Technology》 EI CAS 1997年第4期80-86,共7页
Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce t... Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances. 展开更多
关键词 independent suspension three dimension kinematic analysis multibody system
下载PDF
Kinematics and dynamics analysis of a 3-7R parallel decoupling mechanism 被引量:2
3
作者 郑建勇 史金飞 +1 位作者 张志胜 李为民 《Journal of Southeast University(English Edition)》 EI CAS 2008年第2期183-187,共5页
One kind of movable-pair analysis method is adopted to analyze the configuration of a 3-7R (revolute-pair) parallel decoupling mechanism, and the mechanism's characteristics are summarized. The mechanism has three ... One kind of movable-pair analysis method is adopted to analyze the configuration of a 3-7R (revolute-pair) parallel decoupling mechanism, and the mechanism's characteristics are summarized. The mechanism has three orthogonal distributional branch-chains, and all movable pairs are rotational joints. The movable platform of the mechanism has x, y, z translational decoupling directions. Furthermore, in order to verify the mechanism's decoupling characteristics, the mechanism's kinematics analysis is solved, and the mechanism's direct/inverse kinematics model, input/output velocities and accelerations are deduced, which confirm its decoupling movement characteristics. Finally, one kind of mechanism link decomposed-integrated approach is adopted, and the mechanism's dynamics model is completed with the Lagrange method, which also proves its decoupling force characteristics. All of these works provide significant theory for the further study of the mechanism's control strategy, design, path planning etc. 展开更多
关键词 3-7R parallel decoupling mechanism kinematics DYNAMICS DECOUPLING
下载PDF
Dimensional Synthesis of a 3-DOF Parallel Manipulator with Full Circle Rotation 被引量:10
4
作者 NI Yanbing WU Nan +1 位作者 ZHONG Xueyong ZHANG Biao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第4期830-840,共11页
Parallel robots are widely used in the academic and industrial fields. In spite of the numerous achievements in the design and dimensional synthesis of the low-mobility parallel robots, few research efforts are direct... Parallel robots are widely used in the academic and industrial fields. In spite of the numerous achievements in the design and dimensional synthesis of the low-mobility parallel robots, few research efforts are directed towards the asymmetric 3-DOF parallel robots whose end-effector can realize 2 translational and 1 rotational(2T1R) motion. In order to develop a manipulator with the capability of full circle rotation to enlarge the workspace, a new 2T1 R parallel mechanism is proposed. The modeling approach and kinematic analysis of this proposed mechanism are investigated. Using the method of vector analysis, the inverse kinematic equations are established. This is followed by a vigorous proof that this mechanism attains an annular workspace through its circular rotation and 2 dimensional translations. Taking the first order perturbation of the kinematic equations, the error Jacobian matrix which represents the mapping relationship between the error sources of geometric parameters and the end-effector position errors is derived. With consideration of the constraint conditions of pressure angles and feasible workspace, the dimensional synthesis is conducted with a goal to minimize the global comprehensive performance index. The dimension parameters making the mechanism to have optimal error mapping and kinematic performance are obtained through the optimization algorithm. All these research achievements lay the foundation for the prototype building of such kind of parallel robots. 展开更多
关键词 parallel manipulator kinematic analysis dimensional synthesis
下载PDF
Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber 被引量:4
5
作者 Xu-Dong Zhang Bao-Chun Fan +2 位作者 Ming-Yue Gui Zhen-Hua Pan Gang Dong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第1期66-72,共7页
Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate ... Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems. 展开更多
关键词 Continuously rotating detonation - Three- dimensional flow field structure - Numerical study Detonation parameters deficit ~ Effects of wall geometries
下载PDF
Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)_2 (H_2O)_2]_n (pic)_(2n),[Zn (4,4'-bpy)_2 (H_2O)_2]_n(pic)_(2n) (H_2O)_(2n), and [Zn (4,4'-bpy)_2 (H_2O)_2]_n (4,4'-bpy)_n(H_2O)_n (pic)_(2n) 被引量:1
6
作者 Fu Pei LIANG~1 Zi Lu CHEN~1 +2 位作者 Rui Xiang HU~1 Hong LIANG~1 Zhao Hui ZHOU~2 (1 Department of Chemistry. Guangxi Normal University: Guilin 541004 2 Department of Chemistry. Xiamen University. Xiamen 361005) 《Chinese Chemical Letters》 SCIE CAS CSCD 2000年第4期369-372,共4页
Three Complexes of the formula [Cd (4,4'-bpy)_2 (H_2O)_2]_n. (pic)_(2n) (1) [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n(H_2O)_n (pic)-(2n) (2) and [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n (pic)-(2n)(H_... Three Complexes of the formula [Cd (4,4'-bpy)_2 (H_2O)_2]_n. (pic)_(2n) (1) [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n(H_2O)_n (pic)-(2n) (2) and [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n (pic)-(2n)(H_2O)_n (3) (4.4'-bpy = 4.4'-bipyridine. pic = picric anion ) have been synthesized and characterized by elemental analysis and single-crystal x-ray diffraction. They all have infinite three-dimensional network structure. crystallizing in the monoclinic space group C2/c (1) and Cc (2.3). 展开更多
关键词 Clathration. 4. 4' - bipyridine. picric anion. three - dimensional network.
下载PDF
3-Dimensional Body Measurement Technology
7
作者 周旭东 李艳梅 《Journal of Donghua University(English Edition)》 EI CAS 2002年第4期138-140,共3页
3 - dimensional body measurement technology, the basis of developing high technology in industry, accelerates digital development of aplparel industry. This paper briefly introduces the history of 3 - dimensional body... 3 - dimensional body measurement technology, the basis of developing high technology in industry, accelerates digital development of aplparel industry. This paper briefly introduces the history of 3 - dimensional body measurement technology, and recounts the principle and primary structure of some types of 3 - dimensional automatic body measurement system. With this understanding, it discusses prospect of 3- dimensional CAD and virtual technology used in apparel industry. 展开更多
关键词 3 - dimensional BODY measurement technology digital apparel industry quick response virtual fitting apparel NAD
下载PDF
Mapping the emission line strengths and kinematics of supernova remnant S147 with extensive LAMOST spectroscopic observations 被引量:1
8
作者 Juan-Juan Ren Xiao-Wei Liu +8 位作者 Bing-Qiu Chen Mao-Sheng Xiang Hai-Bo Yuan Yang Huang Hua-Wei Zhang Chun Wang Zhi-Jia Tian Gao-Chao Liu Hong Wu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第9期63-78,共16页
We present extensive spectroscopic observations of supernova remnant (SNR) S 147 collected with the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The spectra were care- fully sky-subtracted t... We present extensive spectroscopic observations of supernova remnant (SNR) S 147 collected with the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The spectra were care- fully sky-subtracted taking into account the complex filamentary structure of S 147. We have utilized all available LAMOST spectra toward S 147, including sky and stellar spectra. By measuring the prominent optical emission lines including Ha, [NII] )λ 6584 and [S n] λλ6717, 6731, we present maps of radial velocity and line intensity ratio covering the whole nebula of S 147 with unprecedented detail. The maps spatially correlate well with the complex filamentary structure of S147. For the central 2° of S147, the radial velocity varies from - 100 to 100 krn s^-1 and has peaks between - 0 and 10 km s^-1. The intensity ratios of Hα/[S n)λλ6717,6731, [Sn] λ 6717/λ 6731 and Ha/IN Hα/λ 6584 peak at about 0.77, 1.35 and 1.48, respectively, with a scatter of 0.17, 0.19 and 0.37, respectively. The intensity ratios are consistent with the literature values. However, the range of variations of line intensity ratios estimated here, which are representative of the whole nebula, is larger than previously estimated. 展开更多
关键词 ISM supernova remnants - ISM kinematics and dynamics - ISM GENERAL
下载PDF
Parametric study on single shot peening by dimensional analysis method incorporated with finite element method 被引量:3
9
作者 Xian-Qian Wu Xi Wang +2 位作者 Yan-Peng Wei Hong-Wei Song Chen-Guang Huang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期825-837,共13页
Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and re- sistance to corrosion fatigue, cracking, etc. Co... Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and re- sistance to corrosion fatigue, cracking, etc. Compressive re- sidual stress and dent profile are important factors to eval- uate the effectiveness of shot peening process. In this pa- per, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of pro- cessing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were de- duced by dimensional analysis method. Secondly, the in- fluence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Fur- thermore, related empirical formulas were given for each di- mensionless parameter based on the simulation results. Fi- nally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this pa- per for analyzing the influence of each individual parameter. 展开更多
关键词 Keywords Shot peening - Maximum compressive residualstress Maximum depth of the dent dimensional analysismethod ~ Finite element method
下载PDF
基于多目标均衡优化的2PRU&1PRS-XY型混联机器人尺度设计方法
10
作者 汤腾飞 沈漪枫 +1 位作者 叶伟 张俊 《农业机械学报》 EI CAS CSCD 北大核心 2024年第4期440-451,共12页
面向复杂结构件机器人加工装备设计需求,提出一种2PRU&1PRS-XY型混联机器人。为将该混联机器人应用于高性能机械加工任务,在其工作空间、运动/力传递性以及灵巧度分析的基础上,定义了用于工作全域性能评价的传递稳定性指标与精度差... 面向复杂结构件机器人加工装备设计需求,提出一种2PRU&1PRS-XY型混联机器人。为将该混联机器人应用于高性能机械加工任务,在其工作空间、运动/力传递性以及灵巧度分析的基础上,定义了用于工作全域性能评价的传递稳定性指标与精度差异性指标,提出了一种基于多目标均衡优化思想的尺度设计方法。该方法采用标准化方法简化多参数设计空间,应用响应面法与主成分分析法提高优化求解效率,结合主客观组合赋权法与基于TOPSIS的Pareto前沿法实现多指标综合性能评分。运用所提方法,得到了4种兼顾优化求解效率和多目标均衡优化的尺度参数设计方案,实现了2PRU&1PRS-XY型混联机器人主要尺度参数的优化设计,为设计者提供了具有不同工程设计倾向的多目标均衡决策参考。 展开更多
关键词 混联机器人 多目标优化 运动学性能 尺度设计
下载PDF
Model fitting of the kinematics of ten superluminal components in blazar 3C 279
11
作者 Shan-Jie Qian 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第7期783-802,共20页
The kinematics of ten superluminal components (C11-C16, C18, C20, C21 and C24) of blazar 3C 279 are studied from VLBI observations. It is shown that their initial trajectory, distance from the core and apparent spee... The kinematics of ten superluminal components (C11-C16, C18, C20, C21 and C24) of blazar 3C 279 are studied from VLBI observations. It is shown that their initial trajectory, distance from the core and apparent speed can be well fitted by the precession model proposed by Qian. Combined with the results of the model fit for the six superluminal components (C3, C4, C7a, C8, C9 and C10) already pub-lished, the kinematics of sixteen superluminal components can now be consistently interpreted in the precession scenario with their ejectiontimes spanning more than 25 yr (or more than one precession period). The results from model fitting show the possible existence of a common precessing trajectory for these knots within a pro- jected core distance of ~0.2-0.4 mas. In the framework of the jet-precession scenario, we can, for the first time, identify three classes of trajectories which are character-ized by their collimation parameters. These different trajectories could be related to the helical structure of magnetic fields in the jet. Through fitting the model, the bulk Lorentz factor, Doppler factor and viewing angle of these knots are derived. It is found that there is no evidence for any correlation between the bulk Lorentz factor of the components and their precession phase (or ejection time). In a companion paper, the kinematics of another seven components (C5a, C6, C7, C17, C19, C22 and C23) have been derived from model fitting, and a binary black-hole/jet scenario was envisaged. The precession model proposed by Qian would be useful for understanding the kine- matics of superluminal components in blazar 3C 279 derived from VLBI observations, by disentangling different mechanisms and ingredients. More generally, it might also be helpful for studying the mechanism of jet swing (wobbling) in other blazars. 展开更多
关键词 radio continuum - galaxies jets - galaxies kinematics - galaxies individual (blazar 3C 279)
下载PDF
Information from the Kinematics of F and G Stars in the Solar Neighborhood
12
作者 Yu-Qin Chen, Gang Zhao and Jian-Rong ShiNational Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2002年第5期419-428,共10页
We have calculated the orbital parameters for 90 stars in Chen et al. and updated the kinematic data for stars in Edvardsson et al. by using the accurate Hipparcos parallaxes and proper motions, and recalculated the ... We have calculated the orbital parameters for 90 stars in Chen et al. and updated the kinematic data for stars in Edvardsson et al. by using the accurate Hipparcos parallaxes and proper motions, and recalculated the α-element abundances in Edvardsson et al. in a way consistent with Chen et al. The two sets of data are combined in a study of stellar populations and characteristics of F & G stars in the solar neighborhood. We confirm the result of Chen et al. that a distinguishable group of stars may belong to the thick disk rather than the thin disk. The ages for the stars are determined using the theoretical isochrones of VandenBerg et al. The age-metallicity relation is investigated for different subgroups according to distance from the sun and galactic orbital parameters. It is found that a mixing of stars with different orbital parameters significantly affect the age-metallicity relation for the disk. Stars with orbits confined to the solar circle all have metallicities [Fe/H] > -0.3 irrespective of their distances from the sun or from the Galactic plane. 展开更多
关键词 stars: kinematics - Galaxy: evolution - Galaxy: solar neighborhood
下载PDF
Kinematics of the Open Cluster System in the Galaxy
13
作者 Jun-Liang Zhao Li Chen Zhong-Liang Zu 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2006年第3期287-296,共10页
Absolute proper motions and radial velocities of 202 open clusters in the solar neighborhood, which can be used as tracers of the Galactic disk, are used to investigate the kinematics of the Galaxy in the solar vicini... Absolute proper motions and radial velocities of 202 open clusters in the solar neighborhood, which can be used as tracers of the Galactic disk, are used to investigate the kinematics of the Galaxy in the solar vicinity, including the mean heliocentric velocity components (u1, u2, u3) of the open cluster system, the characteristic velocity dispersions (σ1,σ2,σ3), Oort constants (A, B) and the large-scale radial motion parameters (C, D) of the Galaxy. The results derived from the observational data of proper motions and radial velocities of a subgroup of 117 thin disk young open clusters by means of a maximum likelihood algorithm are: (u1,u2,u3) = (-16.1 ± 1.0,-7.9 ±1.4,-10.4±1.5) km·s^-1, (σ1,σ2,σ3) = (17.0±0.7, 12.2±0.9, 8.0±1.3) km·S^-1, (A, B) = (14.8±1.0, - 13.0±2.7) km·s^-1 kpc^-1, and (C, D) = (1.5 ± 0.7, -1.2 ±1.5) km·s^-1 kpc^-1. A discussion on the results and comparisons with what was obtained by other authors is given. 展开更多
关键词 Galaxy: kinematics and dynamics - open clusters and associations: general
下载PDF
Observation of Complex Organic Molecules Containing Peptide-like Bonds Toward Hot Core G358.93-0.03 MM1
14
作者 Arijit Manna Sabyasachi Pal 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第7期181-189,共9页
In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past f... In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past few decades,many COMs containing peptide-like bonds have been detected in hot molecular cores(HMCs),hot corinos,and cold molecular clouds,however,their prebiotic chemistry is poorly understood.We present the first detection of the rotational emission lines of formamide(NH_2CHO)and isocyanic acid(HNCO),which contain peptide-like bonds toward the chemically rich HMC G358.93-0.03 MM1,using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array bands 6 and 7.We estimate that the column densities of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(2.80±0.29)×10~(15)cm~(-2)and(1.80±0.42)×10~(16)cm~(-2)with excitation temperatures of 165±21 K and 170±32 K,respectively.The fractional abundances of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(9.03±1.44)×10~(-10)and(5.80±2.09)×10^(-9).We compare the estimated abundances of NH_2CHO and HNCO with the existing threephase warm-up chemical model abundance values and notice that the observed and modeled abundances are very close.We conclude that NH_2CHO is produced by the reaction of NH_2and H_2CO in the gas phase toward G358.93-0.03 MM1.Likewise,HNCO is produced on the surface of grains by the reaction of NH and CO toward G358.93-0.03 MM1.We also find that NH_2CHO and HNCO are chemically linked toward G358.93-0.03 MM1. 展开更多
关键词 ISM individual objects(G358.93-0.03)-ISM abundances-ISM kinematics and dynamics-stars formation-astrochemistry
下载PDF
Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732
15
作者 Arijit Manna Sabyasachi Pal +1 位作者 Tapas Baug Sougata Mondal 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期81-93,共13页
The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the ... The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the presence of complex O-and N-bearing molecules in the star formation regions.So,the investigation of those molecules is crucial to understanding the chemical complexity in the star-forming regions.In this article,we present the identification of the rotational emission lines of N-bearing molecules ethyl cyanide(C_(2)H_(5)CN)and cyanoacetylene(HC_(3)N),and O-bearing molecule methyl formate(CH_(3)OCHO)toward high-mass protostar IRAS18089–1732 using the Atacama Compact Array.We also detected the emission lines of both the N-and O-bearing molecule formamide(NH_(2)CHO)in the envelope of IRAS 18089–1732.We have detected the v=0 and 1 state rotational emission lines of CH_(3)OCHO.We also detected the two vibrationally excited states of HC_(3)N(v7=1 and v7=2).The estimated fractional abundances of C_(2)H_(5)CN,HC_(3)N(v7=1),HC_(3)N(v7=2),and NH_(2)CHO toward IRAS 18089–1732 are(1.40±0.5)×10^(-10),(7.5±0.7)×10^(-11),(3.1±0.4)×10^(-11),and(6.25±0.82)×10^(-11)respectively.Similarly,the estimated fractional abundances of CH_(3)OCHO(v=0)and CH_(3)OCHO(v=1)are(1.90±0.9)×10^(-9)and(8.90±0.8)×10^(-10),respectively.We also created the integrated emission maps of the detected molecules,and the observed molecules may have originated from the extended envelope of the protostar.We show that C_(2)H_(5)CNand HC_(3)N are most probably formed via the subsequential hydrogenation of the CH_(2)CHCNand the reaction between C_(2)H_(2)and CN on the grain surface of IRAS 18089–1732.We found that NH_(2)CHO is probably produced due to the reaction between NH_(2)and H_(2)CO in the gas phase.Similarly,CH_(3)OCHO is possibly created via the reaction between radical CH_(3)O and radical HCO on the grain surface of IRAS 18089–1732. 展开更多
关键词 ISM:individual objects(IRA 18089-1732)(except) ISM:abundances ISM:kinematics and dynamics stars:formation ASTROCHEMISTRY
下载PDF
A Three-Dimensional Kinematics Analysis of a Koi Carp Pectoral Fin by Digital Image Processing 被引量:1
16
作者 Lei Wang Min Xu +3 位作者 Bo Liu Kin Huat Low Jie Yang Shiwu Zhang 《Journal of Bionic Engineering》 SCIE EI CSCD 2013年第2期210-221,共12页
Pectoral fins fascinate researchers for their important role in fish maneuvers. By possessing a complicated flexible structure with several fin rays made by a thin film, the fin exhibits a three-dimensional (3D) mot... Pectoral fins fascinate researchers for their important role in fish maneuvers. By possessing a complicated flexible structure with several fin rays made by a thin film, the fin exhibits a three-dimensional (3D) motion. The complex 3D fin kinematics makes it challenging to study the performance of pectoral fin. Nevertheless, a detailed study on the 3D motion pattern of pectoral fins is necessary to the design and control ofa bio-inspired fin rays. Therefore, a highspeed photography system is introduced in this paper to study the 3D motion ofa Koi Carp by analyzing the two views of its pectoral fin simultaneously. The key motions of the pectoral fins are first captured in both hovering and retreating. Next, the 3D configuration of the pectoral fins is recon- structed by digital image processing, in which the movement of fin rays during fish retreating and hovering is obtained. Fur- thermore, the method of Singular Value Decomposition (SVD) is adopted to extract the basic motion patterns of pectoral fins from extensive image sequences, i.e. expansion, bending, cupping, and undulation. It is believed that the movement of the fin rays and the basic patterns of the pectoral fins obtained in the present work can provide a good foundation for the development and control of bionic flexible pectoral fins for underwater propeller. 展开更多
关键词 highspeed photography Singular Value Decomposition (SVD) three-dimensional kinematics digital image proc-essing
原文传递
HIT-1型月球车的运动学分析 被引量:12
17
作者 蔡则苏 洪炳镕 吕德生 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2003年第9期1098-1101,共4页
为解决轮式移动机器人在崎岖地形中的运动问题,提出了基于摇杆-转向架的带有弹簧和移动滑块的月球车运动学分析方法,在此基础上详细分析了HIT-1型月球车的3D运动机制,推导了月球车的正向运动和反向运动求解.通过使用弹簧和关节滑块改变... 为解决轮式移动机器人在崎岖地形中的运动问题,提出了基于摇杆-转向架的带有弹簧和移动滑块的月球车运动学分析方法,在此基础上详细分析了HIT-1型月球车的3D运动机制,推导了月球车的正向运动和反向运动求解.通过使用弹簧和关节滑块改变车体的质心分布,可加强车体运动重构性,提高车体的牵引力,有效地规划和控制月球车的动作. 展开更多
关键词 HIT-1型月球车 轮式移动机器人 运动学模型 摇杆-转向架 运动机制 运动重构
下载PDF
D-H参数表生成三维机器人模型仿真系统 被引量:31
18
作者 周芳芳 樊晓平 叶榛 《系统仿真学报》 EI CAS CSCD 北大核心 2006年第4期947-950,共4页
一般情况下机器人各关节的几何关系可通过Denavit-Hartenberg(D-H)参数表来描述。提出了采用D-H参数表生成机器人三维虚拟模型的方法,实现了机器人的可视化。仿真系统提供的视图控制功能和场景漫游功能实现了多角度、多位置观测机器人... 一般情况下机器人各关节的几何关系可通过Denavit-Hartenberg(D-H)参数表来描述。提出了采用D-H参数表生成机器人三维虚拟模型的方法,实现了机器人的可视化。仿真系统提供的视图控制功能和场景漫游功能实现了多角度、多位置观测机器人模型的几何结构,并为机器人操作人员提供了训练仿真平台。该系统可以作为机器人学习和机器人结构设计的辅助工具。 展开更多
关键词 D-H参数 机器人运动学 机器人 三维模型 可视化
下载PDF
特发性脊柱侧弯患者步行生物力学特征:三维运动捕捉的横断面分析
19
作者 苟艳芸 侯美金 +4 位作者 江征 陈少清 陈祥 高誉展 王芗斌 《中国组织工程研究》 CAS 北大核心 2025年第3期471-477,共7页
背景:脊柱侧弯的生物力学分析病例数量有限,仅限于对脊柱或下肢独立进行生物力学分析,缺乏对人体多维度整体的评估,难以反映躯干与下肢在日常活动中的运动关系,不利于综合指导临床治疗。目的:通过测量脊柱侧弯患者在步行活动中的脊柱运... 背景:脊柱侧弯的生物力学分析病例数量有限,仅限于对脊柱或下肢独立进行生物力学分析,缺乏对人体多维度整体的评估,难以反映躯干与下肢在日常活动中的运动关系,不利于综合指导临床治疗。目的:通过测量脊柱侧弯患者在步行活动中的脊柱运动学,研究脊柱不同节段及下肢运动学/动力学在步态活动中的关系,以全方位多层次评估脊柱侧弯患者与正常人群在生物力学的差异,为临床防治脊柱侧弯提供循证依据。方法:此研究为一项横断面研究,于2020年7月至2021年6月,在福州大学城、福建中医药大学附属康复医院纳入脊柱侧弯患者28例及同年龄段正常人28例。采用三维运动捕捉系统以100 Hz的采样频率捕捉步态的运动学数据,2块测力台(AMTI 400600,采样频率1500 Hz)嵌于长10 m(数据采集有效长度为4 m),宽2.4 m平地走道采集动力学数据。比较两组受试者执行平地步行时步态时空参数,运动学及动力学参数的差异。所有受试者在纳入后立即接受全脊柱X射线片测量比较两组差异。结果与结论:(1)脊柱侧弯患者肩胛带-躯干相对旋转活动度、胸廓-骨盆相对旋转活动度较正常组小(P<0.05),骨盆旋转活动度相较正常组大(P<0.05)。(2)脊柱侧弯患者髋、膝关节屈伸活动度,髋关节凹凸侧屈伸峰力矩、地反力凸侧内外向峰值较正常组小(P<0.05)。(3)脊柱侧弯患者的膝关节屈伸活动度非对称性指数、肩胛带-躯干相对旋转活动度非对称性指数、胸廓-骨盆相对旋转活动度非对称性指数较正常组大(P<0.05)。(4)上述结果证实,脊柱侧弯患者在平地行走时肩胛带-胸廓-骨盆之间僵硬的运动模式,髋膝关节屈伸活动度减少,髋关节双侧屈伸力矩峰值及地反力凸侧内外向峰值降低。这些特征可以作为康复评估及治疗方案制定的依据。 展开更多
关键词 特发性脊柱侧弯 三维运动捕捉 步态 平地行走 运动学 动力学 运动模式 全脊柱X射线片
下载PDF
2TPT-PTT并联机床运动学研究 被引量:2
20
作者 李兴山 孙奕澎 蔡光起 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2002年第10期1000-1003,共4页
提出了一种新型的 2TPT -PTT三平移自由度并联机床构型·建立了运动学方程 ,给出运动学方程的正、逆解·通过对雅可比矩阵及其逆矩阵的研究 ,分析了机构的奇异性及各杆的速度·在Solidworks和visualNastrandesktop环境下建... 提出了一种新型的 2TPT -PTT三平移自由度并联机床构型·建立了运动学方程 ,给出运动学方程的正、逆解·通过对雅可比矩阵及其逆矩阵的研究 ,分析了机构的奇异性及各杆的速度·在Solidworks和visualNastrandesktop环境下建立其三维实体运动模型 ,并对各杆在三维空间内速度变化做了进一步研究·研究结果表明 :对运动学方程所求正、逆解及雅可比矩阵正确 ,该机构具有结构紧凑、运动平稳、不存在奇异点、易于控制等优点 ,为并联机床的机构设计提供了一定的理论基础· 展开更多
关键词 2TPT-PTT并联机床 运动学 雅可比矩阵 速度 奇异性 三维实体模型 并联机器人
下载PDF
上一页 1 2 12 下一页 到第
使用帮助 返回顶部