检索结果-南通市图书馆

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第S2期49卷 163-173页

作者： DOU Junxia, ZHANG Yiping, YU Guirui, ZHAO Shuangju, WANG Xin & SONG Qinghai Xishuangbanna Tropical Botanical Garden, Chinese Academy of sciences, Kunming 650223, China Institute of Geographic sciences and National Resources Research, Chinese Academy of sciences, Beijing 100101, China Research Centre for Eco-environmental sciences, Chinese Academy of sciences, Beijing 100085, China Graduate University of the Chinese Academy of sciences, Beijing 100049, China 1. Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Kunming 650223 China3. Research Centre for Eco-environmental Sciences Chinese Academy of Sciences Beijing 100085 China4. Graduate University of the Chinese Academy of Sciences Beijing 100049 China2. Institute of Geographic Sciences and National Resources Research Chinese Academy of Sciences Beijing 100101 China

In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna, the sensible and latent heat storage flux within air column, canopy heat storage flux, energy storage by photosynthesis and ground heat storage above the soil heat flux plate, as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry, hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes, meteorological factors and biomass within this tropical seasonal rain forest from January 2003 to December 2004. The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime, and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons. In addition, the absolute values of total heat storage fluxes reached the peak in the hot-dry season, then were higher in the rainy season, and reached the minimum in the cool-dry season. The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime, moreover, the sensible and latent heat storage dominated a considerable fraction of net radiation, while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%. In the daytime, the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 12:00, and then they became lower and differences were small among seasons after 12:00. The energy closure was improved when the storage terms were considered in the energy balance, which indicated that heat storage terms should not been neglected. The energy closure of tropical seasonal rain forest was not very well due to effects of many factors. The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere. Moreo

关键词： heat storage flux energy closure tropical seasonal rain forest Xlshuangbanna.

New agegraphic dark energy as a rolling tachyon

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第1期19卷 600-605页

作者：崔晶磊张莉张敬飞张鑫 Department of Physics College of SciencesNortheastern University

Combining the general relativity and the uncertainty relation in quantum mechanics, the energy density of quantum fluctuations of space-time can be viewed as dark energy. The so-called agegraphic dark energy model is just based on this viewpoint, in which the age of the universe is introduced as the length measure. Recently, the new agegraphic dark energy model was proposed, where the dynamical dark energy is measured by the conformal age of the universe. On the other hand, scalar-field dark energy models like tachyons are often regarded as an effective description of some underlying theory of dark energy. In this paper, we show that the new agegraphic dark energy can be described completely by a tachyon scalar-field. We thus reconstruct the potential and the dynamics of the tachyon scalar-field, according to the evolution of the new agegraphic dark energy.

关键词： new agegraphic dark energy tachyon reconstruction

Genetic diversity assessment of a set of introduced mung bean accessions(Vigna radiata L.)

在线全文

学校读者我要写书评

暂无评论

The Crop Journal 2018年第2期6卷 207-213页

作者： Lixia Wang Peng Bai Xingxing Yuan Honglin Chen Suhua Wang Xin Chen Xuzhen Cheng Institute of Crop sciences Chinese Academy of Agricultural Sciences China National Seed Group Co. Ltd. Institute of Vegetable Crops Jiangsu Academy of Agricultural Sciences

Genetic resources from other countries or regions play an important role in broadening the genetic background of local breeding varieties. Here we describe observations on the adaptability of mung bean germplasm obtained from the United States Department of Agriculture and their genetic diversity assessment using SSR markers. Several accessions were shown to be mixtures,based on their phenotypes for some characters. Most accessions were able to complete their lifecycles when grown in Beijing, China, making them ideal for crossbreeding without day length control. High diversity was revealed by the SSR markers, with an average of 4.2 alleles per locus and a PIC value of 0.650 per locus. STRUCTURE analysis divided the accessions into six *** was no obvious trend of accessions forming groups according to their geographical origin,owing mainly to germplasm exchange and an uneven distribution of accessions. The present results indicate that this germplasm would enrich the local gene pool, and provide information for the further use of germplasm in breeding programs.

关键词： Vigna radiata Plant introduction SSR markers Genetic diversity

SHARP BOUNDS FOR HARDY OPERATORS ON PRODUCT SPACES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2018年第2期38卷 441-449页

作者：魏明权燕敦验 School of Mathematics and Statistics Xinyang Normal University School of Mathematical sciences University of Chinese Academy of Sciences

In this article, we obtain the sharp bounds from LP（Gn） to the space wLP（Gn） for Hardy operators on product spaces. More generally, the precise norms of Hardy operators on product spaces from LP（Gn） to the space... 详细信息

关键词： Hardy operators product spaces wLP(Gn) LPI(Gn) norm

The blueberry(iron nodule)from the Shark Bay area, Western Australia and its implication to the genetic environments of iron nodules on Mars

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2016年第3期59卷 640-650页

作者： LI Jun CHAN Lung Sang LI Yi Liang Department of Earth sciences The University of Hong Kong

Fist-sized iron nodules, extensively found on the ground of Western Australia, were investigated by element analysis(XRF, ICP-MS and ICP-AES), electron microscopes, X-ray diffraction and M?ssbauser spectroscopy. Loosely-packed pisoidic structures of a few to >10 mm in size were observed in the cross-section of nodules. Chemically, the nodules are majorly made of O, Si, Fe and Al, and share similar REE pattern with the loess sourced Greatford concretions from New Zealand. Angular quartz particles, nano-sized goethite and hematite are found to be the major mineral phases. Other minerals, such as detrital zircon, barite and Ce-containing particles can also be observed but of very low abundance. No detectable carbonate or amorphous silica implies that these nodules have experienced little underground fluid alteration. The quartz particles showing particularly three sections of fractal size-distributions, together with their extensive broken features and conchoidal fractures, strongly suggest in situ fragmentation of the host rock with minimum later dynamic sorting. These observations indicate the genetic environment of those nodules is always close to the surface of the tectonically stable ground since their formation. Because of the similarity of climatic and geological features, the genesis and preservation environment of these nodules in Western Australia may provide clues on the formation of Martian iron concretions.

关键词： Iron nodules Western Australia Fractal dimensions In situ fragmentation Mars

Effects of Nozzle-Strut Integrated Design Concepton on the Subsonic Turbine Stage Flowfield

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2014年第5期23卷 494-504页

作者： LIU Jun DU Qiang LIU Guang WANG Pei ZHU Junqiang Institute of Engineering Thermophysics Chinese Academy of Sciences

In order to shorten aero-engine axial length,substituting the traditional long chord thick strut design accompanied with the traditional low pressure(LP) stage nozzle,LP turbine is integrated with intermediate turbine duct(ITD).In the current paper,five vanes of the first stage LP turbine nozzle is replaced with loaded struts for supporting the engine shaft,and providing oil pipes circumferentially which fulfilled the areo-engine structure ***,their bulky geometric size represents a more effective obstacle to flow from high pressure(HP) turbine *** five struts give obvious influence for not only the LP turbine nozzle but also the flowfield within the ITD,and hence cause higher *** investigation has been undertaken to observe the influence of the Nozzle-Strut integrated design concept on the flowfield within the ITD and the nearby nozzle *** to the computational results,three main conclusions are finally ***,a noticeable low speed area is formed near the strut's leading edge,which is no doubt caused by the potential flow ***,more severe radial migration of boundary layer flow adjacent to the strut's pressure side have been found near the nozzle's trailing *** boundary layer migration is obvious,especially close to the shroud ***,radial pressure gradient aggravates this ***,velocity distribution along the strut's pressure side on nozzle's suction surface differs,which means loading variation of the *** it will no doubt cause nonuniform flowfield faced by the downstream rotor blade.

关键词： Intermediate Turbine Duct Integrated Design Concept Flowfield Analysis Total Pressure Loss Analysis

Alignment of beam position monitors in cryomodule of CADS injector Ⅱ

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第6期28卷 95-100页

作者： Jian-Dong Yuan Yuan He Bin Zhang Jun-Hui Zhang Jun-Xia Wu Yong Zhang Feng-Feng Wang Jun-Jie Yao Guo-Zhen Sun Yu-Qin Wan Institute of Modern Physics Chinese Academy of Sciences

Significant temperature difference(300-77 K or even 4 K) can cause large deformations and displacements of the beam position monitors(BPMs),which affect BPMs measurement resolution or even cause their malfunction in cryogenic *** this paper,to check the offset from the mechanical to electrical center in low temperature(77 K),Fourier's law and finite element method are used to simulate *** tracker and micro-alignment telescope are employed in combined BPM calibration,installation and *** calibration error is<0.02 mm,and the installation and monitoring precision are 0.06 mm and 0.01 mm,*** monitored cryo-deformation agrees well with the simulation *** indicate that the combined alignment can improve performance of the BPM *** these guaranteed the success of running the 9.55 MeV@2.14 mA cw protons.

关键词： Beam position monitors Alignment Fourier’s Law Cryomodule CADS ANSYS

Recent Progress in Studies of the Variabilities and Mechanisms of the East Asian Monsoon in a Changing Climate

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric sciences 2019年第9期36卷 887-901页

作者： Wen CHEN Lin WANG Juan FENG Zhiping WEN Tiaojiao MA Xiuqun YANG Chenghai WANG Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Department of Atmospheric and Oceanic sciences Fudan UniversityShanghai 200438China School of Atmospheric sciences Nanjing UniversityNanjing 210023China College of Atmospheric sciences Lanzhou UniversityLanzhou 730000China

Located in a monsoon domain,East Asia suffers devastating natural hazards induced by anomalous monsoon *** Asian monsoon(EAM)research has traditionally been a high priority for the Chinese climate community and is particularly challenging in a changing climate where the global mean temperature has been *** advances in studies of the variabilities and mechanisms of the EAM are reviewed in this paper,focusing on the interannual to interdecadal time *** new results have been achieved in understanding the behaviors of the EAM,such as the evolution of the East Asian summer monsoon(EASM),including both its onset and withdrawal over the South China Sea,the changes in the northern boundary activity of the EASM,or the transitional climate zone in East Asia,and the cycle of the EASM and the East Asian winter monsoon and their *** addition,understanding of the mechanism of the EAM variability has improved in several aspects,including the impacts of different types of ENSO on the EAM,the impacts from the Indian Ocean and Atlantic Ocean,and the roles of mid-to high-latitude ***,some scientific issues regarding our understanding of the EAM are proposed for future investigation.

关键词： East Asian summer monsoon East Asian winter monsoon changing climate monsoon onset and withdrawal transitional climate zone different types of ENSO

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第3期31卷 364-372页

作者： Jingru Song Cuncai Fan Hansong Ma Yueguang Wei LNM Institute of Mechanics Chinese Academy of Sciences

In the present research, hierarchical structure observation and mechanical property characterization for a type of biomaterial are carried out. The investigated bioma- terial is Hyriopsis cumingii, a typical limnetic shell, which consists of two different structural layers, a prismatic ＂pillar＂ structure and a nacreous ＂brick and mortar＂ structure. The prismatic layer looks like a ＂pillar forest＂ with variationsection pillars sized on the order of several tens of microns. The nacreous material looks like a ＂brick wall＂ with bricks sized on the order of several microns. Both pillars and bricks are composed of nanoparticles. The mechanical properties of the hierarchical biomaterial are measured by using the nanoindentation test. Hardness and modulus are measured for both the nacre layer and the prismatic layer, respectively. The nanoindentation size effects for the hierarchical structural materials are investigated experimentally. The results show that the prismatic nanostructured material has a higher stiffness and hardness than the nacre nanostructured material. In addition, the nanoindentation size effects for the hierarchical structural materials are described theoretically, by using the trans-scale mechanics theory considering both strain gradient effect and the surface/interface effect. The modeling results are consistent with experimental ones.

关键词： Biomaterial Hierarchical structure - Mechan-ical property Nanoindentation size effect Trans-scalemechanics