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Influence of Structural Aspects on the Generation Process in planetary Gear Trains

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Engineering（科研） 2011年第10期3卷 1018-1021页

作者： I. Rajasri AVSSKS Gupta YVD Rao 不详

Structural and rotational isomorphism in planetary Gear Trains (PGTs), is tested by Hamming number method. Symmetry in PGTs can be determined from the same Hamming matrix. Bearing of the structural property like symme... 详细信息

关键词： planetary Gear Trains Generation Process of PGTs Isomorphism Symmetry Structural Arrangements Hamming Matrix

The Mesh Efficiency of the planetary Mechanism of 2K-H[D] Style

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Journal of China Textile University(English Edition) 1998年第3期15卷 85-87页

作者：杨照山陈明

The mesh efficiency of the planetary mechanism of 2K - H[D] style is discussed. It comes to a new formula. Usually, an approximate value is taken as the mesh efficiency of a planetary mechanism. If the formula is used, the theoretical value of mesh efficiency can be gotten. The theoretical mesh efficiency can help engineers to know the true efficiency of 2K - H[D] style when it runs. The mesh efficiency serves the transmitting efficiency of a planetary mechanism.

关键词： mesh efficiency gear mechanism planetary .

Effect of Carbon and Sulfur on Iron Melting at High Pressure:Implications for Composition and Evolution of the planetary Terrestrial Cores

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地学前缘 2009年第S1期16卷 204-204页

作者： L.W.Deng~1,Y.W.Fei~2,X.Liu~1,Z.Z.Gong~3 1.School of Earth and Space Science,Peking University,Beijing 100871,China. 2.Geophysical Laboratory,Carnegie Institution of Washington,5251 Broad Branch Road,NW,DC 20015,USA 3.Institute of Spacecraft Environment Engineering,Beijing 100094,China

The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core

关键词： sulfur-carbon-iron high pressure melting planetary core

Tianwen-1 releasing first colored global map of Mars

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Science China(Physics,Mechanics & Astronomy) 2023年第8期66卷 165-166页

作者： Jianghui Ji Xiumin Huang CAS Key Laboratory of planetary Sciences Purple Mountain Observatory Chinese Academy of SciencesNanjing 20023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Mars is known as one of the terrestrial planets in the solar system close to the *** external space environment and planetary physical and chemical properties are similar to the Earth making it the preferred target fo... 详细信息

关键词： Earth terrestrial planetary

Advances in Isotope Geochronology and Isotope Geochemistry:A Preface

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Journal of Earth Science 2022年第1期33卷 1-4页

作者： Xiangkun Zhu Zaicong Wang Huayong Chen MLR Key Laboratory of Isotope Geology Institute of Geology Chinese Academy of Geological Sciences State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Isotope geochronology and isotope geochemistry are important branches of geochemistry. They are based on variations in radiogenic or stable isotope ratios of elements and provide key chemical fingerprints to understand dynamic evolution of the Earth and other planetary bodies from the past to the present, and from their interior to exterior systems.

关键词： isotope geochemistry planetary

Near-Earth Asteroid Surveillance Constellation in the Sun-Venus Three-Body System

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Space(Science & Technology) 2022年第1期2022卷 441-461页

作者： Xingyu Zhou Xiangyu Li Zhuoxi Huo Linzhi Meng Jiangchuan Huang School of Aerospace Engineering Beijing Institute of TechnologyBeijingChina Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijingChina Beijing Institute of Spacecraft System Engineering China Academy of Space TechnologyBeijingChina

The threat of potential hazardous near-Earth asteroid(PHA)impact on Earth is increasingly attracting public *** and early warning of those PHAs are the premise of planetary *** this paper,we proposed a novel concept of surveillance constellation of heterogeneous wide-field near-Earth asteroid(NEA)surveyors(CROWN),in which six spacebased surveyors are loosely deployed in Venus-like orbits to detect the NEAs along the direction of the ***,the concept and overall design of the NEA surveillance constellation are ***,the transfer and deployment trajectory of the surveyors are investigated based on the Sun-Venus three-body *** Sun-Venus libration orbit is taken as the parking orbit,and its stable invariant manifolds are used to reduce the deployment fuel ***,the detection performance of the CROWN was evaluated considering constraints of apparent visual magnitude and field of *** NEA orbit determination(OD)using the CROWN was studied and *** results show that the CROWN can be deployed with a total velocity increment of approximately 300 m/*** the 5 years of observation,99.8%of PHAs can be detected and the OD precision is better than a single-surveyor *** paper can provide a reference for the construction of future asteroid defense system.

关键词： Earth system planetary

Gas-Dust Protoplanetary Disc: Modeling Collisional Interaction of Primordial Bodies

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Journal of Modern Physics 2015年第3期6卷 181-193页

作者： M. Ya. Marov A. V. Rusol Vernadsky Institute of Geochemistry and Analytical Chemistry Russian Academy of Sciences Moscow Russia

One of the key problems in the concept of planetary systems origin and early evolution is solid bodies formation in the protoplanetary gas-dust disc around young stars. Dust particles interactions inside the original fluffy dust clusters of fractal nature resulted from gravitational instability and fragmentation in the disc’s central plane areassumed as the most plausible mechanism of primary bodies set up owing to particles integration within the clusters. Follow upcollisions are regarded to be responsible for eventual growth of primary bodies to the size of planetesimals. We discuss this scenario including chemical nature of particles depending on the disc’s radial temperature distribution and phase transitions. The mathematical model is developed based on the method of penetrating particles with the account for internal structure/properties of bodies involved, complicated patterns of their interaction, and phenomenological approach to describe energy distribution in the contact zone. The model is mainly addressed to the stage of formed solid bodies collisions. The results of numerical evaluation of the model are described involving some constraints for complete or partial destruction of colliding bodies followed by either scattering of collisional fragments orpartial back accumulation.

关键词： planetary System Origin Evolution Protoplanetary Disc Fluffy Cluster Permeable Particles Numerical Modeling Collision Icy-Stone Body

Characteristics of solar-irradiance spectra from measurements,modeling,and theoretical approach

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Light(Science & Applications) 2022年第4期11卷 565-579页

作者： Gerard Thuillier Ping Zhu Martin Snow Peng Zhang Xin Ye Physikalisch-Meteorologisches Observatorium Davos World Radiation Centre(PMODWRC) Davos DorfSwitzerland. Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Science3888 Dong Nanhu RoadChangchun 130033China. Royal Observatory of Belgium Av.Circulaire 31180 BrusselsBelgium. Laboratory for Atmospheric and Space Physics University of Colorado BoulderBoulderCO 80309USA South African National Space Agency(SANSA) Hospital StreetHermanus 7200South Africa University of the Western Cape Department of Physics and AstronomyRobert Sobukwe RdBelvilleCape Town 7535South Africa. National Satellite Meteorological Center China Meteorological AdministrationBejjing 100081China Innovation Center for FengYun Meteorological Satellite China Meteorological AdministrationBeijing 100081China

An accurate solar-irradiance spectrum is needed as an input to any planetary atmosphere or climate *** on the spectral characteristics of the chosen model,uncertainties in the iradiance may introduce significant differences in atmospheric and climate *** is why several solar spectral-irradiance data sets have been published during the last *** have been obtained by different methods:either measurements from a single instrument or a composite of different spectra,or they are theoretical or semi-empirical solar *** this paper,these spectral datasets will be compared in terms of iradiance,power per spectral interval,their derived solar-atmosphere brightness temperature,and time *** the different sources of these spectra are,they generally agree to within their quoted *** solar-rotation effect simultaneously observed by SORCE and PREMOS-PIC ARD is accurately *** 11-year long-term variability remains a difficult task,given the weak activity of solar cycle 24 and long-term instrument aging.

关键词： irradiance planetary climate

Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission Gear Train

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 148-161页

作者： Xiong Zhao Jun Ye Mengyan Chu Li Dai Jianneng Chen Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Key Laboratory of Zhejiang Transplanting Equipment Technology Zhejiang Sci-Tech UniversityHangzhou 310018China

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band *** delivers seedlings ine ciently because of the movement limitations of the linkage *** paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding *** proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio *** allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation *** long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch ***,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control ***,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding *** mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic ***,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried ***-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

关键词： Asymmetric transmission Scallion transplanting High-order gear Non-circular gear planetary gear train