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High-precision RCS measurement of aircraft's weak scattering source

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Chinese Journal of Aeronautics 2016年第3期29卷 772-778页

作者： Hu Chufeng li nanjing Chen Weijun Zhang linxi Science and Technology on UAV Laboratory Northwestern Polytechnical University

The radar cross section （RCS） of weak scattering source on the surface of an aircraft is usually less than -40 dBsm. How to accurately measure the RCS characteristics of weak scattering source is a technical challenge for the aircraft＇s RCS measurement. This paper proposes separating and extracting the two-dimensional （2D） reflectivity distribution of the weak scattering source with the microwave imaging algorithm and spectral transform so as to enhance its measurement preci- sion. Firstly, we performed the 2D microwave imaging of the target and then used the 2D gating function to separate and extract the reflectivity distribution of the weak scattering source. Secondly, we carried out the spectral transform of the reflectivity distribution and eventually obtained the RCS of the weak scattering source through calibration. The prototype experimental results and their analysis show that the measurement method is effective. The experiments on an aircraft＇s low-scattering conformal antenna verify that the measurement method can eliminate the clutter on the surface of aircraft. The precision of measuring a -40 dBsm target is 3 5 dB better than the existing RCS measurement methods. The measurement method can more accurately obtain the weak scattering source＇s RCS characteristics.

关键词： Microwave imaging RCS measurement Reftectivity distributionSpectral transform Weak scattering source

Lower Cretaceous angio-sperm leaf from Wuhe in Anhui,China

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Chinese Science Bulletin 2003年第6期48卷 611-614页

作者： li Haomin nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, nanjing 210008, China nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China

A new early angiosperm leaf species is reported from the Xinzhuang Formation in Wuhe County, Anhui Province. It is probably of Barremian or slightly later in geological age. The fossil leaf is small, no more than 0.6 cm both in length and in width. The leaf veins are well preserved and clearly visible under a low power microscope. Leaf ar-chitectural analysis shows that such a leaf should belong to the first leaf rank of Hickey, i.e. the most primitive one. There are no early angiosperm leaves published completely similar to ours. A new species name of Dicotylophyllum minutissimum sp. nov. is established for the present leaf fos-sils.

关键词：安徽下白垩统早期被子植物叶片结构叶片化石

STUDIES ON GREY MODEL DYNAMIC PREDICTION TO CAVITATION DAMAGE OF TURBINES

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Journal of Hydrodynamics 2003年第5期15卷 29-34页

作者： Wu Fu sheng, Tong Zhong shan, li Yun hui nanjing Hydraulic Research Institute, nanjing 210029, China nanjing Hydraulic Res. Inst. Nanjing 210029 China

In thus paper, cavitation damage of turbines is firstly analyzed andpredicated from the view point of system engineering by use of the grey system theory. A detaileddescription of modeling, dynamic prediction and accuracy test for the grey system of turbines wasgiven. Two special cases for grey dynamic prediction as well as its accuracy test were *** results fall into the grade I, the accuracy is satisfactory and its prediction requirements canbe met well. It shows that the grey system theory can be employed to predict the cavitation damageof turbines, and it can provide a scientific basis for timely investigation and maintenance ofturbines.

关键词： turbine cavitation damage grey prediction

A new pteridinedione from Whitmania pigra

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Chinese Chemical Letters 2010年第5期21卷 603-605页

作者： Yun Feng Zheng,Cun Yu li,Guo Ping Peng,Hong Yang li College of Pharmacy,nanjing University of Chinese Medicine,nanjing 210046,China College of Pharmacy Nanjing University of Chinese Medicine Nanjing 210046 China

A new compound,6-methylsulfinylthieno[3,2-g]-2,4(1H,3H)-pteridinedione,was isolated from the water extract of Whitmania pigra *** structure was elucidated on the basis of NMR and ESIMS spectra.

关键词： Whitmania pigra Heterocycle 6-Methylsulfinylthieno[3,2-g]-2,4(1H,3H)-pteridinedione

Fallback Disk-Involved Spin-Down of Young Radio Pulsars

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Chinese Journal of Astronomy and Astrophysics 2005年第5期5卷 487-494页

作者： Zi-Bo Jiang Xiang-Dong li Department of Astronomy Nanjing University Nanjing 210093

Disks originating from supernova fallback have been suggested to surround young neutron stars. Interaction between the disk and the magnetic field of the neutron star may considerably influence the evolution of the star through the so called propeller effect. There are many controversies about the efficiency of the propeller mechanism proposed in the literature. We investigate the faUback diskinvolved spin-down of young pulsars. By comparing the simulated and measured results of pulsar evolution, we present some possible constraints on the propeller torques exerted by the disks on neutron stars.

关键词： stars: magnetic fields - stars: neutron - pulsars: individual: PSRs B0532+21 B0833+45 B0540-69 B1509-58

The effects of the formula of amino acids enriched BCAA on nutritional support in traumatic patients

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World Journal of Gastroenterology 2003年第3期9卷 599-602页

作者： Xin-Ying Wang Ning li Jun Gu Wei-Qin li Jie-Shou li Medical School of nanjing University,Research Institute of General Surgery,Jinling Hospital,nanjing 210002,Jiangsu Province,China Medical School of nanjing University Research Institute of General Surgery Jinling Hospital 305 East Zhongshan Road Nanjing 210002 Jiangsu Province China. wxinying@***

AIM: To investigate the formula of amino acid enriched BCAA on nutritional support in traumatic patients after ***: 40 adult patients after moderate or large abdominal operations were enrolled in a prospective,randomly and single-blind-controlled study, and total parenteral nutrition (TPN) with either formula of amino acid (AA group, 20 cases) or formula of amino acid enriched BCAA (BCAA group, 20 cases). From the second day after operation, total parenteral nutrition was infused to the patients in both groups with equal calorie and equal nitrogen by central or peripheral vein during more than 12 hours per day for 6 days. Meanwhile, nitrogen balance was assayed by collecting 24 hours urine for 6 days. The markers of protein metabolism were investigated such as amino acid patterns, levels of total protein, albumin, prealbumin,transferrin and fibronectin in ***: The positive nitrogen balance in BCAA group occurred two days earlier than that in AA group. The serum levels oftotal protein and albumin in BCAA group were increased more obviously than that in AA group. The concentration of valine was notably increased and the concentration of arginine was markedly decreased in BCAA group after the formula of amino acids enriched BCAA ***: The formula of amino acid enriched BCAA may normalize the levels of serum amino acids, reduce the proteolysis, increase the synthesis of protein, improve the nutritional status of traumatic patients after operation.

关键词：氨基酸营养支持创伤腹部手术

A Study of Aquifer Thermal Energy Storage:Numerical Simulation of Thermal Storage Experiments in Shanghai

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Acta Geologica Sinica(English Edition) 1989年第3期63卷 297-311页

作者： Xue Yuqun Dept.of Earth Sciences, Nangjing University, nanjing Xie Chunhong Dept.of Mathematics, Nangjing University, nanjing and li Qinfen Shanghai Environmental Geology Center, Shanghai Dept. of Earth Sciences Nangjing University Nanjing China

This paper proposes a 3-D convection-heat dispersion model for a confined aquifer. The governing equation of the model contains not only the traditional convection and conduction terms, but also a heat dispersion term which has often been overlooked in many similar researches. The model is used to describe a series of aquifer thermal energy storage experiments conducted at the Shanghai experimental site, including single-well injection, double-well injection/production and multiple-well injection/prodution tests. The simulated temperatures agree very well with the field data (relative error: 2.8%-4.5%). A detailed description of the model is given, followed by a detailed comparison of simulated and measured temperature distributions.

关键词： A Study of Aquifer Thermal Energy Storage Simulation

The modes of gold-migration in the gossan-type gold deposit

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Chinese Science Bulletin 1999年第S2期44卷 32-33页

作者： HE Jurui and li Ying nanjing Institute of Geology and Mineral Resources, nanjing 210016, China nanjing Institute of Geology and Mineral Resources Nanjing 210016 China

MORE than 30 gossan-type gold deposits have beed discovered in the Middle-Lower Yangtze River *** profile of gold-bearing gossan can be divided into four subzones from upper to lower: （i） gold-deficient or gold-leached gossan (Au contents （0.1-0.8）×10-6) transitonal subzone; （ii） secondary goldconcentration subzone (Au（4-20）×10-6); （iii） oxide and sulfide transitional subzone (Au（0.5-1.5）× 10-6); （iV） Primary sulfide ore (Au（0.5-1） × 10-6). Au Concentration in the subzone （ii） is 2-20 times higher than that in subzone （iV）. Obviously migration and secondary concentration of Au hadhappened in the process of oxidation of primary sulfides. Some geologists indicated that there would be four modes of gold-migration and concentration:（1） gravity separation （mechanism）; （2） organic complex or adsorption; （3） colloidal

关键词： gold migration gossan-type gold deposit.

DISCOVERY OF MONOGRAPTIDS IN BASAL PART OF LOWER SILURIAN FROM S. ANHUI WITH SPECIAL REFERENCE TO THEIR ORIGIN

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古生物学报 1990年第2期29卷 211-215,269页

作者： li Ji-jin(nanjing Institute of Geology and Palaeontology, Academia Sinica)

For a long time, the evolutionary series of a idoraptids-dimorphograptids-monograptids has been generally recognized by graptolite researchers. In the past years, the akidograptids were found to appear in the Lower Silurian Parakidograptus acuminatus Zone, while the dimorphograptids in the P. acuminatus and Orthograpius vesiculosus Zones, but the monograptids appeared as late as in the O. vesiculosus zone; this evolutionary series can be easily accepted by other people. Chen Xu and lin Yao-kun (1978) pu...

关键词： evolutionary earliest Anhui theca probably basal genera Silurian portion locality