检索结果-南通市图书馆

A new heuristic algorithm for the circular packing problem with equilibrium constraints

在线全文

学校读者我要写书评

暂无评论

science china({2. sciences) 2011年第8期54卷 1572-1584页

作者： LIU JingFa 1,2.LI Gang 3.& GENG HuanTong 1 1 School of Computer and Software,nanjing University of information {2. & technology,nanjing 2.0044,china 2.Network information Center,nanjing University of information {2. & technology,{12.,china 3.School of Mathematics and Physics,nanjing University of information {2. & technology,nanjing 2.0044,china School of Computer and Software Nanjing University of Information Science & Technology Nanjing China Network information Center Nanjing University of Information Science & Technology Nanjing China School of Mathematics and Physics Nanjing University of Information Science & Technology Nanjing China

The circular packing problem with equilibrium constraints is an optimization problem about simplified satellite module layout design.A heuristic algorithm based on tabu search is put forward for solving this *** algorithm begins from a random initial configuration and applies the gradient method with an adaptive step length to search for the minimum energy *** jump out of the local minima and avoid the search doing repeated work,the algorithm adopts the strategy of tabu *** the process of tabu search,we improve the traditional neighboring solutions,tabu objects and the acceptance criteria of the current solution *** test two sets of benchmarks consisting of 11 representative instances from the current *** numerical results show that the proposed algorithm breaks the records in seven out of 11 instances,and obtains the optimal solutions for the other four instances.

关键词： equilibrium constraints packing problem heuristic algorithm tabu search layout optimization

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3.and Guo Shengli3.1. College of Life sciences, Zhejiang University, Hangzhou 3.0058, china 2. Imaging Department of Tongji Hospital of Tongji University, Shanghai 2.0065, china 3. College of Mathematics and Physics, nanjing University of information science and technology, nanjing 2.0044, china) College of Life sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China College of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

A three-dimensional variational ocean data assimilation system:Scheme and preliminary results

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china Earth sciences 2006年第11期49卷 1212-1222页

作者： ZHU Jiang1,2. ZHOU Guangqing1, YAN Changxiang1, FU Weiwei1 & YOU Xiaobao1,3.1. International Center for Climate and Environment sciences, Institute of Atmospheric Physics, Chinese Academy of sciences, Beijing 10002.,{2. 2. Jiangsu Key Laboratory of Meteorological Disaster, nanjing University of information science and technology, nanjing 2.0044,{2. 3. Beijing Institute of Applied Meteorology, Beijing 10002.,{2. International Center for Climate and Environment sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Jiangsu Key Laboratory of Meteorological Disaster Nanjing University of Information Science and Technology Nanjing China Beijing Institute of Applied Meteorology Beijing China

A new 3.VAR-based Ocean Variational Analysis System (OVALS) is developed. OVALS is capable of assimilating in situ sea water temperature and salinity observations and satellite altimetry data. As a component of OVALS, a new variational scheme is proposed to assimilate the sea surface height data. This scheme considers both the vertical correlation of background errors and the nonlinear temperature-salinity relationship which is derived from the generalization of the linear balance constraints to the nonlinear in the 3.VAR. By this scheme, the model temperature and salinity fields are directly adjusted from the altimetry data. Additionally, OVALS can assimilate the temperature and salinity profiles from the ARGO floats which have been implemented in recent years and some temperature and salinity data such as from expendable bathythermograph, moored ocean buoys, etc. A 2.-year assimilation experiment is carried out by using OVALS and the Tropical Pacific circulation model. The results show that the assimilation system may effectively improve the estimations of temperature and salinity by assimilating all kinds of observations. Moreover, the root mean square errors of temperature and salinity in the upper depth less than 42. m reach 0.63. and 0.3. psu.

关键词： data assimilation, 3.VAR, sea surface height, ARGO floats.

A Raw Signal Simulator for Bistatic SAR

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2009年第4期22卷 434-443页

作者： Xia Weijie,Zhou Jianjiang College of information science and {2.,{3. University of Aeronautics and Astronautics,{3. 2.0016,china College of information science and {2. Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

This article proposes a new efficient raw signal simulator for the bistatic synthetic aperture radar （SAR） based on 2. fast Fourier transform （FFT） to deal with cases of both ideal trajectory and trajectory deviation. It begins with analyzing the geometric configuration and the range history of the bistatic SAR in side-looking and squint modes of ideal trajectory as well as trajectory deviation. Then a detailed and mathematical study is conducted on the equivalence relation of bistatic-to-monostatic applications （BTMA） in the case of ideal trajectory and trajectory deviation. Also a set of formulas are derived for the equivalence relation between bistatic SAR and monostatic SAR on some reasonable assumptions. Therefore, the application of the simulation method based on the 2. FFT for the monostatic SAR can be extended to the case of bistatic SAR. Finally, the simulation results prove the validity of this method. By comparing the efficiency of the proposed method with that of the time domain method, it is shown that the former is a few orders of magnitude higher.

关键词： bistatic synthetic aperture radar raw signal simulation fast Fourier transform

Features of aerosol optical depth and its relation to extreme temperatures in china during 1980–2.01

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2011年第2期30卷 33-45页

作者： HU Ting SUN Zhaobo LI Zhaoxin Jiangsu Key Laboratory of Meteorological Disaster Nanjing University of Information Scienceand Technology Nanjing 210044 China The Department of Atmospheric science Nanjing University of Information Science andTechnology Nanjing 210044 China Laboratoire de Meteorologie Dynamique CNRS France

Based on Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical thickness （AOT） measurements in 1980–2.01 a study is made of space/time patterns and difference between land and sea of AOT 0.50 μm thick over china,which are put into correlation analysis with synchronous extreme temperature indices （warm/cold day and night）.Results suggest that 1） the long-term mean AOT over china is characterized by typical geography,with pronounced land-sea *** AOT has significant seasonality and its seasonal difference is diminished as a function of latitude.2. On the whole,the AOT displays an appreciably increasing trend,with the distinct increase in the eastern Qinghai-Tibetan plateau and SW china,North china,the mid-lower Changjiang （MiLY） valley as well as the South china Sea,but marginal decrease over western/northern Xinjiang and part of South china.3. The AOT over land and sea is marked by conspicuous intra-seasonal and -yearly oscillations,with remarkable periods at one-,two-yr and more （as interannual periods）.4） Land AOT change is well correlated with extremely temperature ***,the correlations of AOT to the extreme temperature indices are more significant in Eastern china with 110 ° E as the *** high-correlation regions are along the Southern china coastline,the Loess Plateau and the Sichuan Basin,and even higher in North china Plain and the mid-lower Changjiang River reaches.5） Simulations of LMDZ-regional model indicate that aerosol effects may result in cooling all over china,particularly in Eastern *** contribution of aerosol change may result in more decrease in the maximum temperature than the minimum,with decrease of 0.11/0.08 K for zonal average,respectively.

关键词： aerosol optical thickness extreme temperature index space/time pattern trend correlation

A new smoothing scheme for mathematical programs with complementarity constraints

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2010年第7期53卷 1881-1890页

作者： YAN TaoDepartment of information and Computational sciences, College of science, {3. University of science and technology, {3. 2.0094, china Department of information and Computational sciences College of Science Nanjing University of Science and Technology Nanjing China

In this paper, we consider a mathematical program with complementarity constraints (MPCC). We present a new smoothing scheme for this problem, which makes the primal structure of the complementarity part unchanged mostly. For the new smoothing problem, we show that the linear independence constraint qualification (LICQ) holds under some conditions. We also analyze the convergence behavior of the smoothing problem, and get some sufficient conditions such that an accumulation point of stationary points of the smoothing problems is C (M, B)-stationarity respectively. Based on the smoothing problem, we establish an algorithm to solve the primal MPCC problem. Some numerical experiments are given in the paper.

关键词： mathematical program with complementarity constrains MPEC-LICQ B-stationarity C-stationarity M-stationarity

Basin filling algorithm for the circular packing problem with equilibrium behavioral constraints

在线全文

学校读者我要写书评

暂无评论

science china({2. sciences) 2010年第5期53卷 885-895页

作者： LIU JingFa1& LI Gang2.1School of Computer and Software, nanjing University of information {2. & technology, nanjing 2.0044, china 2.chool of Mathematics and Physics, nanjing University of information {2. & technology, nanjing 2.0044, china School of Computer and Software Nanjing University of Information Science & Technology Nanjing China School of Mathematics and Physics Nanjing University of Information Science & Technology Nanjing China

With the background of the satellite module layout design, the circular packing problem with equilibrium behavioral constraints is a layout optimization problem and NP-hard problem in math. For lack of a powerful optimization method, this problem is hard to solve. The energy landscape paving (ELP) method is a class of stochastic global optimization algorithms based on the Monte Carlo sampling. Based on the quasiphysical strategy and the penalty function method, the problem is converted into an unconstrained optimization problem. Here by combining the improved ELP method, the gradient method based on local search and the heuristic configuration update mechanism, a new global search algorithm, basin filling algorithm, is put forward. The numerical results show that the proposed algorithm is effective to solving the circular packing problem with equilibrium behavioral constraints, and is easy to be popularized to other layout optimization problems.

关键词： equilibrium behavioral constraints packing problem layout optimization

Resolution method for overlapping peaks based on the fractional-order differential

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china Chemistry 2007年第6期50卷 797-805页

作者： LI YuanLu1, YU ShengLin2.& ZHENG Gang2.1 College of information & Control, {3. University of information science & technology, nanjing 2.0044, china 2.College of Automation Engineering, {3. University of Aeronautics and Astronautics, {3. 2.0016, china College of information & Control Nanjing University of Information Science & Technology Nanjing China College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing China

Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.

关键词： fractional-order differentiation filter, fractional-order differential, overlapping peaks, voltammetric peak

Tsallis model-based separation of overlapped peak signals

在线全文

学校读者我要写书评

暂无评论

science china({2. sciences) 2010年第4期53卷 823-832页

作者： LI YuanLu*, ZHANG YingChao & TANG HuiQiang College of information and Control, nanjing University of information {3. & technology, nanjing 2.0044, china College of information and Control Nanjing University of Information Science & Technology Nanjing China

A simple scheme for separating overlapped peak signals (OPS) is proposed, with the Tsallis distribution as the model for OPS processing and fractional-order differentiation as tool for the signal analysis, the relationships of the maxima and zero-crossing values of the Tsallis peak signal, separately, to the order of differentiation are established, leading to two types of parameter estimators, which are utilized, by adjusting the peak-shape parameter, to calculate the parameters of position, height and width of the Gaussian, Lorentzian and Tsallis distribution. The obtained characteristic parameters can be employed to fit the peak signals to be treated, thereby fulfilling the OPS decomposition.

关键词： fractional differentials filter overlapped peak signal Tsallis model separation of overlapped peak signals