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Case studies on mesoscale structures of heavy rainfall system in the Yangtze River generated by Meiyu front

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science{1. Earth sciences 2005年第8期48卷 1303-1311页

作者： LIU Liping1. RUAN Zheng1.& QIN Danyu2 1. Chinese Academy of Meteorological sciences, Beijing 1.0081.{1. 2. nanjing institute of Meteorology, nanjing 21.044,{1. 1. Chinese Academy of Meteorological sciences 100081 Beijing China 2. nanjing {1. of Meteorology 210044 Nanjing China

A heavy rainfall system was observed over the Yangtze River during Meiyu season by using dual-Doppler radar systems in the field experiment conducted by the project of National Fundamental Research Planning “Research on formation mechanism and the prediction theory of hazardous weather over china”. The three-dimensional mesoscale kinematic structure and process of a heavy rain on 22 and 23 July, 2002 are investigated by using the radial velocity and dual-Doppler radar technique. The results show that a southwest-northeast oriented rain band with the length of about 1.00 km involves numbers of meso-β or meso-γ-scale convective cells with the size of 20―50 km. The heavy rain band in the middle reaches of the Yangtze River ex-ists in a low-level wind shear. The interaction between southwest low-level jet on the southern side of wind shear and east wind on the northern side formed the updraft. The wind disturbance, wind shear and convergence generate the convective action. The new cell developed in right rear flank of rain band and moved to the southwest wind area, where the vapor is abundant. This kind of echo can last a long time and developed well. The strong convective echoes are often ac-companied by the meso-γ-scale vortex and convergence.

关键词： heavy rainfall in Meiyu front, mesoscale structure, dual-Doppler radar, middle reaches of the Yangtze River, low-level jet.

A new sequential learning algorithm for RBF neural networks

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science{1.(Technological sciences) 2004年第4期47卷 447-460页

作者： YANG Ge1. LV Jianhong1.& LIU Zhiyuan2 1. Department of Power Engineering, Southeast University, nanjing 21.096,{1. 2. Department of Power Engineering, nanjing institute of Technology, nanjing 21.01.,{1. 1. Department of Power Engineering Southeast University 210096 Nanjing China 2. Department of Power Engineering Nanjing Institute of Technology 210013 Nanjing China

Due to their inherent imperfections, it is hard to use the static neural networks for nonlinear time-varying process modeling and prediction, and the minimal resource allocation network (MRAN) is difficult to be realized for its too many regulation parameters. A new sequential learning algorithm for radial basis function (RBF) neural networks based on local projection named Local Projection Network (LPN) is proposed in this paper. The results of validation for several benchmark problems with the new algorithm show that the presented LPN not only has the same level as M-RAN in network size and precision of the outputs, but also has fewer regulation parameters and is more predictable.

关键词： radial basis functions, local projection network, minimal resource allocation network, learning algorithm.

Pollen records of Holocene vegetation and climate changes in the Longzhong Basin of the Chinese Loess Plateau

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Progress in Natural science:Materials International 2007年第12期17卷 1445-1456页

作者： Tang Lingyu1.and An Chengbang2(1. nanjing {1. of Geology and Paleontology, Chinese Academy of sciences, nanjing 2.0008, china 2. Key Laboratory of Western china’s Environment Systems, MOE, Lanzhou University, Lanzhou 730000, china) nanjing {1. of Geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Key Laboratory of Western china’s Environment Systems MOE Lanzhou University Lanzhou 730000 China

Pollen records with an average time resolution of 20-200 years from Holocene loess sections at Dingxi, Qin'an, and other localities of Gansu Province reveal a detailed history of vegetation and climate changes in the western Loess Plateau. For most time of the Holocene, the landscape was dominated by grasslands or forest steppes. However, during the middle Holocene (7.5-5.8 ka BP), relatively dense forests developed, and the endemic vegetation flourished, suggesting a much warmer and more humid climate condition than the present. Superimposed upon this general pattern are several dry intervals marked by the episodic expansion of grasslands or forest steppe. Xeric vegetation expanded after 3.8 ka BP, indicating a trend towards dry conditions.

关键词： pollen records glasslands coniferous forests Holocene Loess Plateau.

Single zircon LA-ICPMS U-Pb dating of Weishan granite (Hunan, South china) and its petrogenetic significance

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science{1. Earth sciences 2006年第8期49卷 816-827页

作者： DING Xing1. CHEN Peirong1. CHEN Weifeng1. HUANG Hongye2 & ZHOU Xinmin1.1. Department of Earth science, {1. University, {1. 21.093, china 2. Research institute No.230, CNNC, Changsha 41.01., china 1. Department of Earth science Nanjing University Nanjing 210093 China 2. Research institute No.230 CNNC Changsha 410011 China

A detailed microstructure analysis and LA-ICPMS U-Pb dating have been done for zir- cons of Weishan granite from Hunan Province, South china. The results indicate that the Weishan granite is a multistage batholith formed during the late Indosinian-early Yanshanian time. The intruded time of the late Indosinian granite is 21..0±1.6Ma and 21..7±1.9Ma (two samples), whereas that of the early Yanshanian granite is 1.7.4±3.5Ma and 1.4.5±5.1.a (two samples). In combination with other geochronological data for Indosinian rocks of South china and the adjacent region, it is inferred that the late Indosinian granites of South china (especially Hunan Province) are probably formed under extension regime as a consequence of post-collision stress relaxation, which is a spontaneous response to intracontinental thickening attributed to the collision and extrusion of two Indosinian seams, namely Qinling-Dabie and Song Ma. Moreover, it is also deduced that the early Yanshanian granites of Hunan Province could not be directly related with the subduction of Paleo-Pacific plate towards Eurasian continent, and they are most likely derivation of the mid- or lower-crustal materials because of decompressional melting under the continuous extension setting.

关键词： CL images, LA-ICPMS U-Pb dating, granite, Weishan, Hunan.

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science{1. Chemistry 2004年第6期47卷 466-479页

作者： SONG Huajie1.2, XIAO Heming1.& DONG Haishan2 1. Department of Chemistry, nanjing University of {1. and Technology, nanjing 21.094, china 2. institute of Chemical Materials, china Academy of Engineering Physics, Mianyang 621.00, china 1. Department of Chemistry Nanjing University of Science and Technology 210094 Nanjing China 2. institute of Chemical Materials China Academy of Engineering Physics 621900 Mianyang China

The symmetry-adapted perturbation theory (SAPT) that has the ability in decompo- sition of the total interaction energy into physically meaningful components is used to provide a more fundamental understanding of intermolecular forces. This work was motivated by the diffi- culty of standard SAPT in computing the intermolecular interactions for large energetic dimer systems. SAPT based on Kohn-Sham orbitals (SAPT(DFT)) proves computationally efficient for these large systems, but has been shown to perform poorly for interaction energy components. The deficiencies of SAPT(DFT) result from wrong asymptotical behaviors of commonly used exchange-correlation potentials. To remove the deficiencies, two asymptotic corrections by means of van Leeuwen and Baerends (LB) model potential and Fermi-Amaldi (FA) type potential were applied into three small test systems comprising He2, HF2 and (N2)2 and a set of larger ni- tramide dimers at several separations. The results showed that when utilizing newly developed frequency-dependent density susceptibilities (FDDS) technique for computing dispersion energy, the FA asymptotic correction is very effective to circumvent these deficiencies in SAPT(DFT) and yields a good accuracy over the LB correction. The FA corrected SAPT(DFT) approach is capa- ble of correctly predicting all the quantitative trends in binding energies for all test cases and substantially reduces computational cost as compared with the standard SAPT calculations. The successful application of the approach to nitramide dimer demonstrates that it potentially pro- vides a good means to calculate accurately intermolecular forces in larger system such as en- ergetic systems.

关键词： intermolecular interaction, density functional theory (DFT), symmetry adapted perturbation theory (SAPT), asymptotic correction, frequency-dependent density susceptibilities (FDDS).

Pedodiversity: a controversial concept

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Journal of Geographical sciences 2001年第1期11卷 110-116页

作者： CHEN Jie1. ZHANG Xue-lei1. GONG Zi-tong1. WANG Jun2 (1. institute of {1. science, CAS, nanjing 2.0008, china 2. Surveying and Mapping Bureau of Jiangsu Province, nanjing 2.0008, china) institute of {1. science CAS Nanjing China Surveying and Mapping Bureau of Jiangsu Province Nanjing China

The concept of pedodiversity and its measurement methodology proposed and developed by Ibá?ez research term is introduced. An attempt to apply pedodiversity to analyze spatial soil variation and distribution patterns on the global scale is briefly demonstrated. Furthermore, constructive comments and criticisms on pedodiversity and its measurement from the noted pedologists and ecologists are outlined. Finally, potential applications of pedodiversity in soil science and other relevant disciplines are discussed.

关键词： pedodiversity soil global distribution spatial variation species richness species evenness Shannon Index

Stability of a linear oscillator with damping force of the fractional-order derivative

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science{1.(Physics,Mechanics & Astronomy) 2010年第2期53卷 345-352页

作者： WANG ZaiHua1.2 & HU HaiYan1.1.institute of Vibration Engineering Research,{1. University of Aeronautics and Astronautics,{1. 21.01.,china 2 institute of science,PLA University of science and Technology,{1. 21.1.1.china 1. institute of Vibration Engineering Research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

It begins with the study of damping representation of a linear vibration system of single degree of freedom (SDOF),from the view point of fractional calculus. By using the idea of stability switch,it shows that the linear term involving the fractional-order derivative of an order between 0 and 2 always acts as a damping force,so that the unique equilibrium is asymp-totically stable. Further,based on the idea of stability switch again,the paper proposes a scheme for determining the stable gain region of a linear vibration system under a fractional-order control. It shows that unlike the classical velocity feedback which can adjust the damping force only,a fractional-order feedback can adjust not only the damping force,but also the elastic re-storing force,and in addition,a fractional-order PDα control can either enlarge the stable gain region or narrow the stable gain region. For the dynamic systems described by integer-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay in the open left half-plane,while for the systems with fractional-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay within a sector in the complex plane. Analysis shows that the proposed method,based on the idea of stability switch,works effectively in the stability analysis of dynamical systems with fractional-order derivatives.

关键词： vibration system fractional-order derivative asymptotical stability stability switch

Delayed Hopf bifurcation in time-delayed slow-fast systems

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science{1.(Technological sciences) 2010年第3期53卷 656-663页

作者： ZHENG YuanGuang1.& WANG ZaiHua1.2 1.institute of Vibration Engineering Research,{1. University of Aeronautics and Astronautics,{1. 21.01.,china 2 institute of science,PLA University of science and Technology,{1. 21.1.1.china 1. institute of Vibration Engineering Research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential *** the two delayed's have different *** delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious *** a time-delayed system,the evolution of the system depends not only on the present state but also on past *** this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's *** shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.

关键词： time delay delayed bifurcation Hopf bifurcation slow-fast systems exit-point entry-exit function

Seasonal variation of global stratosphere-troposphere mass exchange

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Progress in Natural science:Materials International 2007年第12期17卷 1466-1475页

作者： Guo Dong1.2, Lu Daren2 and Sun Zhaobo1.1. institute of Atmospheric {1.s, nanjing University of Information {1. and Technology, nanjing 21.044, china 2. LAGEO, institute of Atmospheric Physics, Chinese Academy of {1.s, Beijing 1.0029, china) institute of Atmospheric {1.s Nanjing University of Information Science and Technology Nanjing 210044 China LAGEO Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

By Wei formula in pressure coordinate, the stratosphere-troposphere mass exchange (STME) is diagnosed globally for 44 years from 1.58 to 2001.using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis datasets. Regions of mass flux into the stratosphere are found over Indonesia, bay of Bangladesh and the mid-west coast of South Africa. Compensating mass outflow from the stratosphere appears mainly over mid-latitudes near large-scale troughs. Upward and downward transport of mass at the middle and high latitudes accompany with each other. Mass flux into troposphere is stronger in autumn and winter than in spring and summer. Strong downward mass flux into the troposphere occurs in eastern Asia the whole year with nearly stable sites. Although the area of eastern Asia accounts for only 5.6% of that of the northern hemisphere (NH), its net mass exchange reaches 1..83% of that of the NH, which means that research on STME of eastern Asia is greatly important to that of the NH and even the global areas. Air across the tropopause enters more from stratosphere to troposphere than that from troposphere to stratosphere, which is possibly related with systematic bias of the assimilated datasets and with persistent rise of the tropopause height. Contributions of the mass exchange and the mass flux exchange in the NH and southern hemisphere (SH) on their latitudes increase from equator to pole, with larger contributions in the NH. Mass exchange and mass flux exchange per areas at high latitudes are larger than that at low latitudes, which means greater mass exchange efficiency at high latitudes.

关键词： stratosphere troposphere mass exchange seasonal variation.