检索结果-南通市图书馆

An Economical Approach to Four-dimensional Variational Data Assimilation

Advances in Atmospheric Sciences 2010年第4期27卷 715-727页

作者：王斌刘娟娟王曙东成巍刘娟刘成思 Qingnong XIAO Ying-Hwa KUO State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Graduate School of the Chinese Academy of Sciences Beijing 100049 College of Marine Science University of South Florida St. Petersburg FL 33701 USA Mesoscale and Microscale Meteorology Division National Center for Atmospheric ResearchBoulder CO 80307-3000 USA

Four-dimensional variational data assimilation （4DVar） is one of the most promising methods to provide optimal analysis for numerical weather prediction （NWP）. Five national NWP centers in the world have successfully applied 4DVar methods in their global NWPs, thanks to the increment method and adjoint technique. However, the application of 4DVar is still limited by the computer resources available at many NWP centers and research institutes. It is essential, therefore, to further reduce the computational cost of 4DVar. Here, an economical approach to implement 4DVar is proposed, using the technique of dimension- reduced projection （DRP）, which is called ＂DRP-4DVar.＂ The proposed approach is based on dimension reduction using an ensemble of historical samples to define a subspace. It directly obtains an optimal solution in the reduced space by fitting observations with historical time series generated by the model to form consistent forecast states, and therefore does not require implementation of the adjoint of tangent linear approximation. To evaluate the performance of the DRP-4DVar on assimilating different types of mesoscale observations, some observing system simulation experiments are conducted using MM5 and a comparison is made between adjoint-based 4DVar and DRP-4DVar using a 6-hour assimilation window.

关键词： 4DVar adjoint dimension reduction historical sample observing system simulation experiment

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

Straw strip mulching in a semiarid rainfed agroecosystem achieves winter wheat yields similar to those of full plastic mulching by optimizing the soil hydrothermal regime

引用

The Crop Journal 2022年第3期10卷 879-892页

作者： Yuwei Chai Qiang Chai Rui Li Yawei Li Changgang Yang Hongbo Cheng Lei Chang Shouxi Chai State Key Laboratory of Aridland Crop Science Gansu Agricultural UniversityLanzhou 730070GansuChina College of Agronomy Gansu Agricultural UniversityLanzhou 730070GansuChina College of Bioscience and Technology Gansu Agricultural UniversityLanzhou 730070GansuChina

Straw strip mulching(SM)is a new mulching *** 2012 to 2018,SM’s effects on soil moisture and temperature and production performances were compared with other mulching practices,using three treatments:full-cover plastic mulch(PM),no mulch with wheat sown in rows as the control(CK),and SM with 50%to 59%of the field area *** with CK,on average over six growing seasons,SM and PM increased grain yield by 27.0%and 21.7%,straw yield by 21.6%and 22.6%,kernels ha;by 26.6%and 19.0%,net income by 29.8%and-25.0%,soil temperature at 5 cm by-1.5°C and 0.2°C from overwintering to maturity,and soil water storage at 0–200 cm by 25 and 22 mm,*** increase in soil moisture in SM and PM was greater in the early period(overwintering to jointing)than in the later period(booting to maturity)and at 0 to 120 cm than at 120–200 cm in the early *** the mean evapotranspiration of whole growth period across six seasons was similar among treatments,SM and PM increased water consumption during the key formation period of yield components after overwintering by 16 and 32 mm,respectively,while reducing it before *** with CK,SM and PM had the effects of warming during overwintering and cooling after *** increasing water consumption after overwintering and ratio of transpiration to evapotranspiration and providing favorable soil temperature for multiple growth stages and more sufficient soil moisture,SM and PM promoted vegetative growth and increased kernels ha^(-1),the main mechanisms by which SM and PM increased grain yield relative to *** to PM,SM is a more economically beneficial and environment-friendly technology for dryland wheat production.

关键词： Mulch pattern Yield formation Vegetative growth Water use efficiency Hydrothermal interaction

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

Use of the advanced microwave sounding unit data to improve typhoon prediction

引用

Progress in Natural Science:Materials International 2009年第3期19卷 369-376页

作者： Guo Deng a,*, Dalin Zhang b, Tong Zhu c, Angsheng Wang d a National Meteorological Center, Beijing 100081, China b Department of Atmospheric and Oceanic Science, University of Maryland, Maryland 20742, USA c Cooperative Institute for Research in the Atmosphere, Colorado State University, Colorado 80523, USA d Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China National Meteorological Center Beijing 100081 China Department of Atmospheric and Oceanic Science University of Maryland Maryland 20742 USA Cooperative Institute for Research in the Atmosphere Colorado State University Colorado 80523 USA Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The effects of incorporating the advanced microwave sounding unit (AMSU-A) data with a modified Zhu-Zhang-Weng vortex- bogussing algorithm on typhoon prediction are examined through the use of the PSU/NCAR Mesoscale Model version 5 (MM5). The AMSU-A data contain the vertical distribution of the retrieved temperature from satellite brightness temperature, with the geopo- tential height and wind fields derived through a series of statistical and diagnostic calculations. The advantages of the modified vortex- bogussing algorithm include the incorporation of realistic asymmetric typhoon structures, the balanced dynamics with the background field, the easiness to implement and the effcient computations. To test the effciency of this vortex-bogussing algorithm, the Typhoon Dan event in 1999 is simulated by incorporating the derived AMSU-A fields into the initial conditions of the MM5 modeling system. Results show significant improvements in the track and intensity of the storm, as compared to the simulation without the AMSU-A data. Therefore, this modified vortex-bogussing algorithm can be easily implemented on any typhoon modeling system, which will improve the real-time forecast of tropical cyclones.

关键词： AMSU Satellite retrieval Typhoon prediction

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Comb-like Poly(N-(2-hydroxypropyl) methacrylamide) Doxorubicin Conjugates: The Influence of Polymer Architecture and Composition on the Biological Properties

引用

Chinese Journal of Polymer Science 2018年第11期36卷 1225-1238页

作者： Hao Tang Jin Tang Yi Shen Wen-Xuan Guo Min Zhou Rui-Hua Wang Ni Jiang Zhi-Hua Gan Qing-Song Yu The State Key Laboratory of Organic-inorganic Composites Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology College of Life Science and Technology Beijing University of Chemical Technology Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology

The synthesis and structure-property correlation of poly（N-（2-hydroxypropyl） methacrylamide）（PHPMA） conjugates with various architectures including random, block, branched or star-like structures and compositions have been thoroughly explored. However, related synthesis and structure-property data are still lacking for comb-like PHPMA. In this work, we report the synthesis of comb-like PHPMA copolymer-doxorubicin （DOX） conjugates with different backbone/side-chain lengths and location of drug moieties. Well-defined comb-like PHPMA-DOX conjugates are obtained via the combination of controlled radical polymerization and fractional precipitation techniques. The influences of structural factors on the biological properties such as cellular uptake, blood circulation and tumor accumulation have been investigated. Long blood circulation and efficient tumor accumulation can be achieved by proper control of the comb number, length and location of drug moieties. These facile comb-like structures possess great potentials in future theranostics for brachytherapy or surgical navigation.

关键词： Poly(N-(2-hydroxypropyl) methacrylamide) Comb-like copolymer Anticancer drug delivery Synthesis Structure-property correlation

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

Structural Topology Design of Container Ship Based on Knowledge-Based Engineering and Level Set Method

引用

China Ocean Engineering 2015年第4期29卷 551-564页

作者：崔进举王德禹史琪琪 State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University American Bureau of Shipping

Knowledge-Based Engineering （KBE） is introduced into the ship structural design in this paper. From the implementation of KBE, the design solutions for both Rules Design Method （RDM） and Interpolation Design Method （IDM） are generated. The corresponding Finite Element （FE） models are generated. Topological design of the longitudinal structures is studied where the Gaussian Process （GP） is employed to build the surrogate model for FE analysis. Multi-objective optimization methods inspired by Pareto Front are used to reduce the design tank weight and outer surface area simultaneously. Additionally, an enhanced Level Set Method （LSM） which employs implicit algorithm is applied to the topological design of typical bracket plate which is used extensively in ship structures. Two different sets of boundary conditions are considered. The proposed methods show satisfactory efficiency and accuracy.

关键词： Knowledge-Based Engineering (KBE) Level Set Method (LSM) Gaussian Process ( GP)

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

Application of Mythen detector:In-situ XRD study on the thermal expansion behavior of metal indium

引用

Science China(Physics,Mechanics & Astronomy) 2016年第7期59卷 62-69页

作者： Rong Du ZhongJun Chen Quan Cai JianLong Fu Yu Gong ZhongHua Wu Institute of High Energy Physics and University of the Chinese Academy of Sciences Chinese Academy of Sciences

A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility （BSRF）, which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction （XRD） full-profiles. In this paper, the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector. The indium was heated from 303 to 433 K with a heating rate of 2 K/rain. The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds. Rietveld refinement was used to extract the structural parameters. The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis. The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point （429.65 K）. The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature, while the c-axis contracts with a cubic dependency on temperature. By the time-resolved XRD measurements, it was observed that the [200] preferred orientation can maintain to about 403.15 K. While （110） is the last and detectable crystal plane just before melting of the polycrystalline indium foil. This study is not only beneficial to the application of metal indium, but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.

关键词： Mythen detector thermal expansion Rietveld refinement XRD indium foil

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 giant central red disk galaxy at redshift z=0.76:Challenge to theories of galaxy formation

引用

Science China(Physics,Mechanics & Astronomy) 2021年第7期64卷 137-141页

作者： Kun Xu ChengZe Liu YiPeng Jing Marcin Sawicki Stephen Gwyn Department of Astronomy School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai200240China Tsung-Dao Lee Institute Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai200240China Canada Research Chair Department of Astronomy&Physics and the Institute for Computational AstrophysicsSaint Mary’s UniversityHalifaxB3H 3C3Canada NRC-Herzberg Astronomy and Astrophysics National Research Council of CanadaVictoriaV9E 2E7Canada

We report a giant red central disk galaxy in the XMM-LSS north region. The region is covered with a rich variety of multi-band photometric and spectroscopic observations. Using the photometric data of the Canada-France-Hawaii Telescope Legacy Survey(CFHTLS) and spectroscopic observation of the baryon oscillation spectroscopic survey(BOSS), we find that the galaxy has a stellar mass of ~1011.6 M⊙. The galaxy has a red color and has an old stellar population, and thus its star formation has *** the photometric image data of the Hyper Suprime-Cam(HSC) Subaru Strategic Program, we demonstrate that its luminosity profile is perfectly described by a Sérsic form with n=1.22 consistent with that of a disk. We also analyze its environment based on the VIMOS Public Extragalactic Redshift Survey(VIPERS) photometric catalog, and find that its close neighbors are all less massive, indicating that our observed galaxy is sitting at the center of its dark matter host halo. Existence of such a giant red central disk galaxy seriously challenges the current standard paradigm of galaxy formation, as there is no known physical mechanism to explain the quenching of its star formation. This conclusion is supported by state-of-the-art hydrodynamical simulations of galaxy formation.

关键词： disk galaxies galaxy quenching massive galaxies

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

Characterizing Spatial Patterns of Phenology in Cropland of China Based on Remotely Sensed Data

引用

Agricultural Sciences in China 2010年第1期9卷 101-112页

作者： WU Wen-bin YANG Peng TANG Hua-jun ZHOU Qing-bo CHEN Zhong-xin Ryosuke Shibasaki Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences/Key Laboratory of Resources Remote Sensing and Digital Agriculture Ministry of Agriculture Beijing 100081 P.R.China Center for Spatial Information Science University of Tokyo Tokyo 153-8505 Japan

This study used time-series of global inventory modeling and mapping studies （GIMMS） normalized difference vegetation index （NDVI） datasets at a spatial resolution of 8 km and 15-d interval to investigate the spatial patterns of cropland phenology in China. A smoothing algorithm based on an asymmetric Gaussian function was first performed on NDVI dataset to minimize the effects of anomalous values caused by atmospheric haze and cloud contamination. Subsequent processing for identifying cropping systems and extracting phenological parameters, the starting date of growing season （SGS） and the ending date of growing season （EGS） was based on the smoothed NVDI time-series data. The results showed that the cropping systems in China became complex as moving from north to south of China. Under these cropping systems, the SGS and EGS for the first growing season varied largely over space, and those regions with multiple cropping systems generally presented a significant advanced SGS and EGS than the regions with single cropping patterns. On the contrary, the phenological events of the second growing season including both the SGS and EGS showed little difference between regions. The spatial patterns of cropping systems and phenology in Chinese cropland were highly related to the geophysical environmental factors. Several anthropogenic factors, such as crop variety, cultivation levels, irrigation, and fertilizers, could profoundly influence crop phenological status. How to discriminate the impacts of biophysical forces and anthropogenic drivers on phenological events of cultivation remains a great challenge for further studies.

关键词： phenology NDVI time-series cropping systems the starting date of growing season (SGS) the ending date of growing season (EGS) spatial pattern

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

In vitro vasodilatory effect of aqueous leaf extract of Thymus serrulatus on thoracic aorta of Guinea pigs

引用

Asian Pacific Journal of Tropical Biomedicine 2015年第1期5卷 15-18页

作者： Bekesho Geleta Mebrahtu Eyasu Selamu Kebamo Asfaw Debella Eyasu Makonnen Abiy Abebe Directorate of Traditional and Modern Medicine Research Ethiopian Public Health Institute St.Paul's Hospital Millennium Medical College Department of Pharmacology Wollega University Department of Pharmacology Addis Ababa University College of Health SciencesSchool of MedicineDepartment of Pharmacology

Objective:To investigate the vasodilatory effecl of Thymus serrulatus(***) aqueous leaf extract on KCl(high K^+.80 mmol/L) induced precontracted isolated thoracic aorta rings on guinea pigs and the role of aorta endothelium on this ***:Guinea pig thoracic aorta was removed and placed in an organ bath containing Krebs-Henseleit solution and aorta contractions were recorded ***:The results revealed that *** aqueous leaf extract(0.5-5 mg/mL)significantly(P<0.001) reduced KCl-induced contractions of guinea pig thoracic aorta in both intact(n=5) and denuded(n=5) endothelium in a concentration dependent manner,and the vasodilatory effect of the extract on intact endothelium was significantly(P<0.05) higher than that on denuded ***(10 μmol/L) significantly(P<0.001) increased the vasodilatory effect of extract in intact endothelium as compared to methylene blue(10μmol/L).atropine(10 μmol/L) and indomethacin(10 μmol/L).The effecl was more obvious on intact than that on denuded ***:The present findings demonstrate that *** aqueous leaf extract has vasodilator)' activity which might result in antihypertensive effect and its vasodilatory effect is *** might support the traditional claim of the plant in hypertensive.

关键词： Thymus serrulatus Guinea pig Aqueous extract Endothelium Organ bath Vasodilatory effect

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

Big data in healthcare:Conceptual network structure,key challenges and opportunities

引用

数字通信与网络:英文版 2023年第4期9卷 856-868页

作者： Leonardo B.Furstenaua Pedro Leivas Michele Kremer Sott Michael S.Dohan Jose Ricardo Lopez-Robles Manuel J.Cobo Nicola Luigi Bragazzi Kim-Kwang Raymond Choo Post-Graduate Program in Industrial Engineering Federal University of Rio Grande Do SulPorto Alegre90035-190Brazil University of Santa Cruz Do Sul Av.Independencia 2293Santa Cruz Do SulRSBrazil Business School Unisinos UniversityAv.Dr.Nilo Peçanha 160091330-002Porto AlegreBrazil Faculty of Business Administration Lakehead UniversityThunder BayOntarioCanada Autonomous University of Zacatecas Av.Ramon Lopez Velarde Col.CentroZacatecas98000Mexico Department of Computer Science and Artificial Intelligence Andalusian Research Institute in Data Science and Computational Intelligence(DaSCI)University of GranadaGranada 18071Spain York University ON M3J 1P3Canada Department of Information Systems and Cyber Security University of Texas at San AntonioSan AntonioTX78249USA

Big data is a concept that deals with large or complex data sets by using data analysis tools(e.g.,data mining,machine learning)to analyze information extracted from several sources *** data has attracted wide attention from academia,for example,in supporting patients and health professionals by improving the accuracy of decision-making,diagnosis and disease *** research aimed to perform a Bibliometric Performance and Network Analysis(BPNA)supported by a Scoping Review(SR)to depict the strategic themes,thematic evolution structure,main challenges and opportunities related to the concept of big data applied in the healthcare *** this goal in mind,4857 documents from the Web of Science covering the period between 2009 to June 2020 were analyzed with the support of SciMAT *** bibliometric performance showed the number of publications and citations over time,scientific productivity and the geographic distribution of publications and research *** strategic diagram yielded 20 clusters and their relative importance in terms of centrality and *** thematic evolution structure presented the most important themes and how it changes over ***,we presented the main challenges and future opportunities of big data in healthcare.

关键词： Big data Healthcare digitalization Bibliometric Strategic intelligence Co-word analysis SciMAT

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

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：