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Study on the simulation of transparency of Lake Taihu under different hydrodynamic conditions

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Science china Earth Sciences 2006年第Z1期49卷 162-175页

作者： PANG Yong, LI Yiping & LUO Liancong College of Environmental Science and Engineering, Hohai university, nanjing 210098, china nanjing institute of Geography & Limnology, Chinese Academy of Sciences, nanjing 210098, china College of Environmental Science and Engineering Hohai University Nanjing China nanjing institute of Geography & Limnology Chinese Academy of Sciences Nanjing China

It was indicated in this study that there were negative relations between the concentrations of suspended solid (SS) and transparency according to the analysis of measured data of Lake Taihu. Their relations in pervious studies were reviewed, which showed that the changes of transparency in Lake Taihu could be reflected by simulating suspended solid concentration (SSC). Measured data showed that the changes of SSC with wind speed were similar at different water *** increased with the increasing of wind speed. Both wave and lake current of Lake Taihu had positive relations with SSC. However, wave was the main factor affecting sediment suspension, while flow took the second place. In this study, a numerical model coupling lake current, wave and SSC of Lake Taihu was developed. In the SS model, the combined effects of wave and current were *** amounts of suspended and deposited sediments near the lake bed surface layer were treated separately. The stochastic characteristics of turbulent flow pulsation near lake beds were also considered, and the start-up conditions of sediment suspension were introduced to the model. The model elucidated the mutual exchange processes between sediment particles in SS and active sediments within and on the bed surface layer. Simulated results showed that lake current had relatively significant effects on the SSC at littoral areas of Lake Taihu, while SSC at the central area of the lake was mainly influenced by wave. The changes of transparency with SSC were simulated for Lake Taihu using this model. Calculated results were validated by measured data with good fitness, which indicated that the model is basically suitable for the simulation and prediction of transparency of Lake Taihu.

关键词： transparency, suspended solid, hydrodynamic, sediment suspension, model.

INVESTIGATIONS ON LASER SHOCK-PROCESSING (LSP) TO IMPROVE FATIGUE LIFE OF SMALL HOLE IN AIRCRAFT STRUCTURES

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Chinese Journal of Aeronautics 1997年第1期10卷 41-45页

作者： Zhang Yongkang(institute of Acoustics and Lab of Modern Acoustics,nanjing university, nanjing, china, 210093)Yu Chengye(nanjing university of Aeronautics and Astronautics, nanjing, china, 210016) institute of Acoustics Lab of Modern Acoustics Nanjing University Nanjing 210093 China nanjing Univ. Aero. and Astronaut. Nanjing 210016 China

Laser shock-processing (LSP) is of particular advantage for improving fa-tigue behavior of small holes and blind holes. Because there are not good accessibility andpassage, these holes cannot be treated by shot peening or cold extrusion. The fatigue livesof aircraft aluminum alloy 2024-T62 are increased greatly by means of optimization oflaser shocking parameters. With 95 % confidence, the mean fatigue life of LSP specimensis 4. 35~7, 75 times larger than that of the un-shocked ones.

关键词： laser shock-processing(LSP) aircraft structures aluminum alloys fatigue life

Effect of bismuth species on propylene aromatization over BiHZSM-5 catalysts

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Chinese Journal of Chemistry 1994年第4期12卷 295-304页

作者： MIAO, Cheng-MingDepartment of Chemistry, Jiangsu institute of Education, nanjing, Jiangsu 210013, chinaWU, Chuan-Chang FENG, Lin Department of Chemistry, nanjing university, nanjing, Jiangsu 210008, china Department of Chemistry Jiangsu Institute of Education Nanjing Jiangsu 210013 China Department of Chemistry Nanjing University Nanjing Jiangsu 210008 China

The catalytic behavior of Bi-impregnated HZSM-5 zeolites in propylene aroma-tization and the surface properties of the zeoh'tes were determined by microreactor, XRD, XPS, NH3-TPD and IR-TPD. The mechanism of the reaction and the effect of surface properties of the zeolites on the reaction were also investigated. Experimental data showed that Bi-impregnation made the strength of B-acid sites decrease, the strength of L-acid sites and the concentration of both strong B-acid sites and strong L-acid sites increase. Bi-impregnation also induced sub-strong acid sites. These were the factors that made the aromatic products of the reaction increase. The strong interaction between the impregnant and zeolite surface reached maximum at Bi2O3 = 3.5 wt%. Above this value, covering effect of impregnant caused a decrease of aromatic products.

关键词： Aromatization Bi-impregnation ZSM-5 Propylene.

Study of Time Delay Estimation for Multichannel Noise Suppresion System

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The Journal of china Universities of posts and telecommunications 1997年第1期4卷 55-58,77页

作者： Zhu Qi (Department of Radio Engineering, nanjing university of posts and telecommunications, nanjing 210003, P. R. china)

Accurate time delay estimation is very important in multichannel noise suppression systems. This paper has proposed a new method to reduce the effect of noise on the estimation of time delay between different channels. Our new time delay algorithm will more considerably reduce the estimation error, compared with the conventional autocorrelation function method.

关键词： speech processing time delay noise suppression

FIXED-POINT BLIND ADAPTIVE MULTIUSER DETECTION ALGORITHM FOR IR UWB SYSTEMS IN MULTIPATH CHANNEL

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Journal of Electronics(china) 2010年第2期27卷 157-165页

作者： Wang Feng Xu Chengqi College of telecommunications ＆ Information Engineering Nanjing University of Posts ＆ Telecommunications Nanjing 210003 China

Using the hypothesis that data transmitted by different users are statistically independent of each other,this paper proposes a fixed-point blind adaptive multiuser detection algorithm for Time-Hopping (TH) Impulse Radio (IR) Ultra Wide Band (UWB) systems in multipath channel,which is based on Independent Component Analysis (ICA) idea. The proposed algorithm employs maximizing negentropy criterion to separate the data packets of different users. Then the user characteristic se-quences are utilized to identify the data packet order of the desired user. This algorithm only needs the desired user’s characteristic sequence instead of channel information,power information and time-hoping code of any user. Due to using hypothesis of statistical independence among users,the proposed algorithm has the outstanding Bit Error Rate (BER) performance and the excellent ability of near-far resistance. Simulation results demonstrate that this algorithm has the performance close to that of Maximum-Likelihood (ML) algorithm and is a suboptimum blind adaptive multiuser detection algorithm of excellent near-far resistance and low complexity.

关键词： Ultra Wide Band (UWB) MultiUser Detection (MUD) Bind adaptive Fixed-point Multipath channel

Intelligent Video Traffic Smooth Mechanism for Multimedia Communication

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The Journal of china Universities of posts and telecommunications 2000年第1期7卷 36-40,45页

作者： GE Ling, WU Xin-yu (Department of Electronic Engineering, nanjing university of posts and telecommunications, nanjing 210003, P.R.china) Department of Electronic Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 P.R.China

A principal challenge in supporting real-time video services over ATM is the need to provide synchronous play-out in the face of stochastic end-to-end network delays. In this paper, an intelligent traffic smooth mechanism ( ITSM ) is proposed to meet the continuity requirement which is composed of a back-propagation neural network ( BPNN ) traffic predictor, a play-out buffer, and a fuzzy neural network ( FNN ) based play-out rate determinator. The BPNN traffic predictor online predicts the mean packet rate of the traffic in the future interval ( FI ) and the FNN is designed to adaptively determinate the play-out time according to the number of packets in the buffer and the traffic character predicted. Simulation results show that compared to the window mechanism, ITSM achieves high continuity with accepted delay. Furthermore, ITSM can be adaptively modified to meet the QoS of different kinds of services by FNN parameter training.

关键词： ATM QoS BPNN FNN

Chaos Synchronization between the Coupled Modified Chua's Circuits with Nonlinear Quadratic Function x|x|

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The Journal of china Universities of posts and telecommunications 2002年第4期9卷 28-32页

作者： JIANG Guo ping (Department of Electronic Engineering, nanjing university of posts & telecommunications, nanjing 210003, P.R. china) Department of Electronic Engineering Nanjing University of Posts & Telecommunications Nanjing 210003 P.R. China

This paper studies chaos synchronization in the modified Chua ' s circuitwith nonlinear quadratic function x|x| using a unidirectional Linear coupling approach. A newsufficient condition is derived for chaos synchronization between the two unidirectional coupledmodified Chua ' s circuits with x x I based on the Lyapunov stability theory. A simulation exampleis given for demonstration .

关键词： chaos synchronization lyapunov theory modified chua' s circuit with x|x|

A self-steering close-talking microphone array

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Progress in Natural Science:materials International 2005年第11期15卷 1044-1049页

作者： PENG Ke, YANG Xinfeng and XU Boling (State Key Laboratory of Modern Acoustics, institute of Acoustics, nanjing university, nanjing 210093, china) State Key Laboratory of Modern Acoustics Institute of Acoustics Nanjing University Nanjing 210093 China

For communication in extremely noisy environments, close-talking microphone arrays are useful. Differential microphone array systems possessing excellent nearfield directivity and strong farfield-noise reduction capability are very suitable for close-talking situations. In order to improve the focusing effect at the desired bearing in the nearfield, we propose a novel self-steering system of close-talking arrays with the first-order differential sub-arrays in this paper. Calculations of directivity patterns and directivity factors show that when a kind of optimized beamforming technique is adopted even small arrays with a focusing configuration will exhibit a satisfactory nearfield directivity which is electronically steerable within a specific range. The superiority of the proposed array system is verified by experiments with real acoustic data.

关键词： close-talking array differential array self-steering directivity factor.

A Multi-Scale Gradient Algorithm Based on Morphological Operators

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The Journal of china Universities of posts and telecommunications 2000年第1期7卷 56-59页

作者： LU Guan-ming (Department of Information Engineering, nanjing university of posts & telecommunications, nanjing 210003, P.R.china) Department of Information Engineering Nanjing University of Posts & Telecommunications Nanjing 210003 P.R.China

Watershed transformation is a powerful morphological tool for image segmentation. However, the performance of the image segmentation methods based on watershed transformation depends largely on the algorithm for computing the gradient of the image to be segmented. In this paper, we present a multi-scale gradient algorithm based on morphological operators for watershed-based image segmentation, with effective handling of both step and blurred edges. We also present an algorithm to eliminate the local minima produced by noise and quantization errors. Experimental results indicate that watershed transformation with the algorithms proposed in this paper produces meaningful segmentations, even without a region-merging step.

关键词： morphological gradient watershed image segmentation mathematical morphology