检索结果-南通市图书馆

Combination of terrestrial reference frames based on space geodetic techniques in SHAO:methodology and main issues

Research in Astronomy and Astrophysics 2017年第9期17卷 1-14页

作者： Bing He Xiao-Ya Wang Xiao-Gong Hu qun-He zhao Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Aerospace Dynamics Xi'an 710043China

Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared

关键词： astrometry w reference systems -- techniques: interferometers -- methods: data analysis

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

Supramolecular Macrocycle Regulated Single-Atom MoS_(2)@Co Catalysts for Enhanced Oxygen Evolution Reaction

引用

Energy & Environmental Materials 2024年第5期7卷 283-291页

作者： Shuai Cao Wenzhuo Wu Chaozhong Liu Leqian Song qun Xu Huacheng Zhang Yanli zhao School of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'an 710049China Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450052China Department of Materials Science and Engineering Zhengzhou University Zhengzhou 450001China School of Chemistry Chemical Engineering and BiotechnologyNanyang Technological University21 Nanyang Link Singapore 637371Singapore

The development of active water oxidation catalysts for water splitting has stimulated considerable ***,the design and building of single atom Co sites using a supramolecular tailoring strategy are reported,that is,the introduction of pillar[4]arene[1]quinone(P4A1Q)permits mononuclear Co species stereoelectronically assembled on MoS_(2)matrix to construct an atomically dispersed MoS_(2)@Co catalyst with modulated local electronic structure,definite chemical environment and enhanced oxygen evolution reaction *** calculations indicate that immsobilized single-Co sites exhibit an optimized adsorption capability of oxygen-containing intermediates,endowing the catalyst an excellent electrocatalytic oxygen evolution reaction activity,with a low overpotential of 370 mV at 10 mA cm^(-2)and a small Tafel slope of 90 mV dec^(-1).The extendable potential of this strategy to other electrocatalysts such as MoS_(2)@Ni and MoS_(2)@Zn,and other applications such as the hydrogen evolution reaction was also *** study affords new insights into the rational design of single metal atom systems with enhanced electrocatalytic performance.

关键词： electrocatalysis oxygen evolution reaction pillararenequinone single atoms transition-metal dichalcogenides

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

Enhanced grain refinement of Al-Si alloys by novel Al-V-B refiners

引用

Journal of Materials Science & Technology 2021年第35期94卷 104-112页

作者： Chenxi zhao Yang Li Jin Xu qun Luo Ying Jiang Qiling Xiao Qian Li State Key Laboratory of Advanced Special Steels Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and EngineeringShanghai UniversityShanghai 200444China Materials Genome Institute Shanghai UniversityShanghai 200444China

Al-V-B master alloy is promising for refining Al-Si alloys,yet its optimal composition with superior efficacy remains to be *** this work,the evolution of refining phases in the Al-10 Si/Al-V-B system with different V:B ratios was evaluated by thermodynamic calculations,based on which the Al-V-B refiners with V:B=1:1 and 5:1 were *** trails demonstrated that they could significantly reduce the grain size of Al-10 Si(wt.%)alloy from 1736 to 184-245μm with industrial addition *** examinations results clarify that when V:B ratio is 1:1 the nucleation particle is(V,Al)B_(2),which has a VB_(2)-AlB_(2) core-shell structure and therefore presents the nucleation capability as AlB_(2) *** V:B ratio is as high as 5:1,the nucleation particle is pure VB_(2).Density functional theory(DFT)calculation indicates that(0001)VB_(2)/(111)α-Al interface has the lowest interfacial energy such that highest nucleation potency among other types of diboride/α-Al interfaces under *** outcomes of this work provide fundamental guidance to develop superior V-B based refiners for Al-Si alloys.

关键词： Al-Si alloys Grain refinement Al-V-B Interfacial structure Thermodynamic calculation

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

A Comprehensive Study of a Low-Grade Heat-Driven Cooling and Power System Based on Heat Current Method

引用

Journal of Thermal Science 2024年第4期33卷 1523-1541页

作者： zhao Tian XU Ronghong XIN Yonglin HE Kelun MA Huan YUAN Mengdi CHEN qun School of Energy Storage Science and Engineering North China University of TechnologyBeijing100144China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing100084China

Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy *** work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid *** system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior *** off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system *** off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current *** optimization aiming to minimize the total thermal conductance is also *** efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.

关键词： combined cooling and power system organic Rankine cycle absorption chiller cascade heat utilization heat current method off-design analysis

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

Influence of a Flood Event on Salinity and Nutrients in the Changshan Archipelago Area (Northern Yellow Sea)

引用

Journal of Ocean University of China 2012年第3期11卷 419-426页

作者： ZHANG Guangtao zhao Zengxia LIU Changhua LIU qun REN Jianming Jiaozhou Bay Marine Ecosystem Research Station Institute of OceanologyChinese Academy of SciencesQingdao 266071China The Yellow Sea Marine Observation Station Institute of OceanologyChinese Academy of SciencesQingdao 266071China

River discharge can deliver nutrients to the coastal zone and change the hydrologic properties of the water column. Soon after a flash flood from the Yalu River (Northeast China) in August 2010, we investigated the salinity and nutrient concentrations, as well as other environmental conditions in the Changshan Archipelago area, located approximately 100 km west of the river mouth in the northern Yellow Sea. Diluted water was mainly observed in the upper layers shallower than 15 m, with surface salinity between 18.13 and 30.44 in the eastern study area and between 28.16 and 29.72 in the western area. Surface salinity showed a significant negative correlation with concentrations of dissolved nutrients (P < 0.05), but not with that of Chlorophyll-a (Chl-a), dissolved oxygen (DO), particulate materials or pH. The average concentrations of nitrite, nitrate, and silicic acid decreased from the surface layer to bottom layer and were significantly higher in the east area than in the west area (P < 0.05). In contrast, average ammonium and phosphate concentrations were highest in the bottom layer of both areas, with no significant spatial differences. DO varied between 6.06 and 8.25 mg L-1 in the surface layer, and was significantly higher in the eastern area than in the western area in the surface and middle layers. Chl-a concentration was constantly below 4.09 μg L-1. Our work demonstrated the strong influences of Yalu River on proportions of various nutrient components in the Changshan Archipelago area. Silicic acid and total inorganic nitrogen levels were significantly elevated comparing to phosphate in the eastern area. Such changes can potentially induce phosphate limit to phytoplankton growth.

关键词： Yalu River flash flood diluted water salinity nutrients Changshan Archipelago

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

Effect of axial preloading on mechanical behavior during the free-end torsion of an extruded AZ31 magnesium alloy

引用

International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1351-1360页

作者： qun Li Dan Meng Zhichang Fu Hui zhao Chong Yang Yan Peng Baodong Shi Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education School of Mechanical EngineeringYanshan UniversityQinhuangdao 066004China National Engineering Research Center for Equipment and Technology of Cold Rolled Strip School of Mechanical EngineeringYanshan UniversityQinhuangdao 066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China

Large plastic deformation commonly occurs during the practical forming process in *** with uniaxial tension/compression,torsion is a more effective approach to investigate mechanical behavior under large *** response of the large strain torsion of magnesium alloy is sensitive to the initial texture and ***,an extruded AZ31 alloy was pre-stressed in tension and compression to introduce dislocations and twins in the current ***,torsion tests were conducted to clarify the effects of twinning and dislocation on subsequent deformation *** corresponding microstructure and deformation mechanisms were explored on the basis of viscoplastic self-consistent(VPSC)*** experimental observations on stress-strain responses and pole figures were captured by simulation *** was found that twins make less contribution to plastic deformation,which results in small change in texture direction under pure torsion and torsion after *** activity of the slip/twin system and the mechanical properties are affected by different initial textures and active conditions of the ***,the stress state during combined tension-torsion loading benefits the reduction of texture intensity.

关键词： magnesium alloy torsion twinning dislocation texture viscoplastic self-consistent

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

Simulation of the dynamic disturbance characteristics of the soft sediment in the Diexi ancient dammed lake,China

引用

Journal of Mountain Science 2021年第4期18卷 990-1002页

作者： WANG Xiao-qun WEI Jie zhao Jia-kang ZHOU Zhou HUANG Xin College of Environment Geology and Civil Engineering Chengdu University of TechnologyChengdu 610059China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China JSTI Group Nanjing 211100China

In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China,10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine *** this paper,the soft-sediment disturbances caused by earthquakes in the Diexi ancient dammed lake were studied based on field investigations and laboratory core observations.A two-to three-degree-of-freedom spring-type earthquake simulation vibration table was used to carry out disturbance tests on lacustrine sediments under different dynamic *** results support the following conclusions:(1)The disturbance layers in the lacustrine sediments were caused by strong earthquakes in the region.(2)The characteristics of the disturbance layers are related to the seismic parameters and the degree of sediment consolidation.(3)The greater the earthquake intensity is,the greater the disturbance amplitude is;moreover,the lower the consolidation degree is,the greater the disturbance amplitude.(4)The simulation tests verify that the disturbance layers in the sediments of the Diexi ancient dammed lake correspond to strong earthquakes in the *** results are valuable for ongoing palaeoseismic research in the region.

关键词： Ancient dammed lake Lacustrine sediment Soft sediment Palaeoearthquake Simulation test

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

Interannual variability of dimethylsulfide in the Yellow Sea

引用

Journal of Oceanology and Limnology 2022年第2期40卷 551-562页

作者： Sijia WANG qun SUN Siyu LI Jiawei SHEN Qian LIU Liang zhao College of Marine and Environmental Sciences Tianjin University of Science and TechnologyTEDATianjin 300222China School of Marine Science and Technology Tianjin UniversityTianjin 300072China

The 22-year(1998-2019)surface seawater dimethylsulfi de(DMS)concentrations in the Yellow Sea(YS)were hindcasted based on satellite sea surface temperature(SST)and chlorophyll-a(Chl-a)data using a generalized additive mixed model(GAMM).A continuous monthly dataset of DMS concentration in the YS was obtained after using the data interpolation empirical orthogonal function(DINEOF)to reconstruct missing information in the ***,the interannual DMS variability in the YS was *** results indicated that the monthly climatological DMS concentration in the YS was 3.61 nmol/*** concentrations in the spring and summer were signifi cantly higher than those in the autumn and *** concentrations were highest in coastal YS waters and lowest primarily in off shore YS *** DMS variability between 1998 and 2019 was subdivided into two inverse phases:with the exception of the central YS,DMS increased before the turning point and decreased *** turning point in interannual DMS variation was earlier in the inshore YS as compared to the central *** analysis identifi ed some signifi cant patterns of interannual variation in the DMS anomaly in the *** a appeared to be the main factor infl uencing interannual trends in DMS in the *** DMS variability was under the joint control of Chl a and ***,short-term interannual DMS variation(2-3 years)was primarily related to SST,while longer term interannual DMS variation(6-8 years)was signifi cantly correlated with Chl a and SST.

关键词： interannual variability dimethylsulfi de hindcasting generalized additive mixed modelling Yellow Sea

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

Design of Self‑Reconfigurable Multiarm Robot Mechanism Based on Deployable Kinematic Chains

引用

Chinese Journal of Mechanical Engineering 2020年第5期33卷 34-50页

作者： Fu‑qun zhao Sheng Guo Hai‑Jun Su Hai‑Bo Qu Ya‑Qiong Chen School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

As the structures of multiarm robots are serially arranged,the packaging and transportation of these robots are often *** ability of these robots to operate objects must also be *** this issue,this paper presents a type of multiarm robot that can be adequately folded into a designed *** robot can achieve different operation modes by combining different arms and ***,deployable kinematic chains(DKCs)are designed,which can be folded into a designated area and be used as an arm structure in the multiarm robot *** strategy of a platform for storing DKCs is *** on the restrictions in the storage area and the characteristics of parallel mechanisms,a class of DKCs,called base assembly library,is ***,an assembly method for the synthesis of the multiarm robot mechanism is proposed,which can be formed by the connection of a multiarm robot mechanism with an operation object based on a parallel mechanism *** formed parallel mechanism can achieve a reconfigurable characteristic when different DKCs connect to the operation *** this method,two types of multiarm robot mechanisms with four DKCs that can switch operation modes to perform different tasks through autonomous combination and release operation is *** obtained mechanisms have observable advantages when compared with the traditional mechanisms,including optimizing the occupied volume during transportation and using parallel mechanism theory to analyze the switching of operation modes.

关键词： Design Multiarm robot Deployable kinematic chain Parallel mechanism Motion set

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 characteristics of spontaneous near-inertial wave generation from an anticyclonic mesoscale eddy

引用

Journal of Oceanology and Limnology 2022年第2期40卷 413-427页

作者： Bo zhao Zhenhua XU qun LI Wenjia MIN Yang WANG Baoshu YIN CAS Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of SciencesQingdao 266071China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Engineering Laboratory for Marine Ranching Institute of OceanologyChinese Academy of SciencesQingdao 266071China Polar Research Institute of China Shanghai 200136China

The generation and propagation characteristics of near-inertial waves(NIWs)generated spontaneously from a quasi-geostrophic anticyclonic mesoscale eddy in a rotating and stratifi ed fl uid were investigated by three-dimensional numerical *** are generated over a long time interval as a forced response to balanced baroclinic mesoscale *** such eddies,NIW generation from balanced flow is an inevitable result as the evolution of ***,the baroclinicity of mesoscale eddies is an essential condition for this NIW generation *** spontaneously generated NIWs radiate horizontally toward the eddy center and propagate upward in vertical *** forcing of the NIWs moves downward along the eddy axis from the location of maximum temperature anomaly of the mesoscale *** moving speed of the forcing is independent on the balanced mesoscale eddies but is determined by the ratio of buoyancy to inertial *** the forcing reaches the bottom of the mesoscale eddy,the spontaneous NIW generation process *** intensity in this spontaneous generation process is strengthened with the increase of the Rossby and Froude *** research to gain a solid understanding of the role of the Rossby and Froude numbers is necessary for the parameterization of spontaneous NIW generation from quasi-geostrophic mesoscale eddies in general circulation model.

关键词： near-inertial waves(NIWs) anticyclonic mesoscale eddy spontaneous generation

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

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：