检索结果-南通市图书馆

FLOCKING OF MULTI-AGENT DYNAMIC SYSTEMS WITH GUARANTEED GROUP CONNECTIVITY

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2008年第3期21卷 337-346页

作者： xiaoli li Yugeng xi Department of Automation Shanghai Jiao Tong University Shanghai 200240 China

This paper investigates distributed flocking problem where the information exchange among agents is modeled by the communication topology changing with time. Previous research on this problem establishes group stabilization by assuming that the dynamic topology is connected all the time, which however cannot be guaranteed by most proposed distributed control laws. In this paper, a distributed algorithm to distill a necessary subgraph of the initial communication topology is presented. This subgraph covers all the vertices of the communication topology and is proved to be connected as long as the initial communication topology is connected. A distributed control law is then designed to pursue the flocking motion while preserving all the edges in this subgraph. In this way, connectivity can be preserved all the time, and flocking problem is thus solved only provided the initial communication topology of multi-agent system is connected.

关键词： Connectivity distributed control flocking multi-agent system

Quantitative structure-activity relationship study on the biodegradation of acid dyestuffs

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2007年第7期19卷 800-804页

作者： li Yin xi Dan-li College of Environmental Science and Engineering Dong Hua University Shanghai 201620 China.

Quantitative structure-biodegradability relationships （QSBRs） were established to develop predictive models and mechanistic explanations for acid dyestuffs as well as biological activities. With a total of four descriptors, molecular weight （MW）, energies of the highest occupied molecular orbital （EHOMO）, the lowest unoccupied molecular orbital （ELUMO）, and the excited state （EES）, calculated using quantum chemical semi-empirical methodology, a series of models were analyzed between the dye biodegradability and each descriptor. Results showed that EHOMO and Mw were the dominant parameters controlling the biodegradability of acid dyes. A statistically robust QSBR model was developed for all studied dyes, with the combined application of EHOMO and Mw. The calculated biodegradations fitted well with the experimental data monitored in a facultative-aerobic process, indicative of the reliable prediction and mechanistic character of the developed model.

关键词： quantitative structure-activity relationship (QSAR) acid dyestuff biodegradability decolorization

Fractal Characteristics and Prediction of Backsilting Quantity in Yangtze Estuary Deepwater Channel

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2018年第3期32卷 341-346页

作者： li Lan-xi PAN Yun li li Business School Hohai University Marine Science and Technology College Zhejiang Ocean University Institute of Port Coastal and Offshore Engineering Ocean Collage Zhejiang University

Fractal interpolation has been an important method applied to engineering in recent years. It can not only be used to fit smooth curve and stationary data but also show its unique superiorities in the fatting of non-smooth curve and non-stationary data. Through analyzing such characteristic values as average value, standard deviations, skewness and kurtosis of measured backsilting quantities in the Yangtze Estuary 12.5 m Deepwater Channel during2011–2017, the fractal interpolation method can be used to study the backsilting quantity distribution with *** to the fractal interpolation made on the channel backsilting quantities from January 2011 to December2017, there was a good corresponding relationship between the annual(monthly) siltation quantities and the vertical scaling factor. On this basis, a calculation formula for prediction of the backsilting quantity in the Yangtze Estuary Deepwater Channel was constructed. With the relationship between the predicted annual backsilting quantities and the vertical scaling factor, the monthly backsilting quantities can be obtained. Thus, it provides a new method for estimating the backsilting quantity of the Yangtze Estuary Deepwater Channel.

关键词： Yangtze Estuary Deepwater Channel backsilting quantity fractal interpolation prediction

Nonlinear Coupled Dynamics Analysis of A Truss Spar Platform

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2016年第6期30卷 835-850页

作者： li Cheng-xi ZHANG Jun Department of Mechanical Engineering Massachusetts Institute of Technology Department of Civil Engineering Texas A&M UniversityCollege Station

Accurate prediction of the offshore structure motion response and associate mooring line tension is important in both technical applications and scientific research. In our study, a truss spar platform, operated in Gulf of Mexico, is numerically simulated and analyzed by an in-house numerical code ＇COUPLE＇. Both the platform motion responses and associated mooring line tension are calculated and investigated through a time domain nonlinear coupled dynamic analysis. Satisfactory agreement between the simulation and corresponding field measurements is in general reached, indicating that the numerical code can be used to conduct the time-domain analysis of a truss spar interacting with its mooting and riser system. Based on the comparison between linear and nonlinear results, the relative importance of nonlinearity in predicting the platform motion response and mooring line tensions is assessed and presented. Through the coupled and quasi-static analysis, the importance of the dynamic coupling effect between the platform hull and the mooting/riser system in predicting the mooting line tension and platform motions is quantified. These results may provide essential information pertaining to facilitate the numerical simulation and design of the large scale offshore structures.

关键词： coupled dynamic analysis nonlinear effect hybrid wave model (HWMO

Crystal plasticity behavior of single-crystal pure magnesium under plane-strain compression

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第7期36卷 541-549页

作者： Bai-li xi Gang Fang Department of Mechanical Engineering Tsinghua University Beijing 100084China State Key Laboratory of Tribology Beijing 100084China

A phenomenological crystal plasticity constitu- tive model for magnesium single crystal was presented. Four deformation mechanisms （including basal （a）, pris- matic （a）, pyramidal （c ＋ a） slip and tension twin） and their interactions were considered. Twin-induced lattice reorientation was also incorporated in the model. The proposed model was then applied to the simulation of plane-strain compression deformation for different orien- tations. Related material parameters were calibrated at first according to the classical channel-die tests. The predicted macro-and microscopic responses, along with the experi- mental results, show strong orientation-dependent proper- ties. It is also found in the simulation that basal slip in the twinned region is active even before the saturation of twin activity in a twin-favored case. Furthermore, the effect of an initial deviation angle on the mechanical responses was evaluated, which is proved to be also orientation-depen- dent. Basal slip is found to be easily activated due to a slight deviation, while a slight deviation in the twin-fa- vored case could result in a significant difference in the mechanical behavior after the reorientation. The effort on the study of magnesium single crystal in the present work contributes to further polycrystalline analysis.

关键词： Magnesium Crystal plasticity Slip and twin Orientation deviation

Travelling Solitary Wave Solutions for Generalized Time-delayed Burgers-Fisher Equation

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第8期52卷 284-286页

作者： DENG xi-Jun HAN li-Bo li xi School of Information and Mathematics Yangtze University Jingzhou 434023 China College of Physical Science and Technology Yangtze University Jingzhou 434023 China Department of Mathematics University of Kansas Kansas 66045 USA

In this paper,travelling wave solutions for the generalized time-delayed Burgers-Fisher equation *** using the first-integral method,which is based on the ring theory of commutative algebra,we obtain aclass of travelling solitary wave solutions for the generalized time-delayed Burgers-Fisher equation.A minor error in theprevious article is clarified.

关键词： solitary wave first-integral method ring theory time-delayed Burgers-Fisher equation

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2020年第6期31卷 1167-1177页

作者： PENG Han CHENG Ting li xi School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

In target tracking applications,the Doppler measurement contains information of the target range rate,which has the potential capability to improve the tracking ***,the nonlinear degree between the measurement and the target state increases with the introduction of the Doppler ***,target tracking in the Doppler radar is a nonlinear filtering *** order to handle this problem,the Kalman filter form of best linear unbiased estimation(BLUE)with position measurements is proposed,which is combined with the sequential filtering algorithm to handle the Doppler measurement further,where the statistic characteristic of the converted measurement error is calculated based on the predicted information in the sequential ***,the algorithm is extended to the maneuvering target tracking case,where the interacting multiple model(IMM)algorithm is used as the basic framework and the model probabilities are updated according to the BLUE position filter and the sequential filter,and the final estimation is a weighted sum of the outputs from the sequential filters and the model *** results show that compared with existing approaches,the proposed algorithm can realize target tracking with preferable tracking precision and the extended method can achieve effective maneuvering target tracking.

关键词： Kalman filter best linear unbiased estimation(BLUE) measurement conversion sequential filter

FATIGUE FRACTURE BEHAVIOR OF LOW CARBON MARTENSITE AND MARTENSITE/BAINITE DUPLEX STRUCTURE IN STEEL 20CrMnMo

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1992年第3期5卷 212-217页

作者： li Yongjun xi′an Jiaotong University,xi′an,China xi'an Jiaotong Univ Xi'an China

Fatigue crack propagation rate,da/dN,and threshold stress intensity range,ΔK_(th),of steel 20CrMnMo containing low carbon martensite or low carbon martensite/bainite(LCM/B) duplex structure,obtained by oil quenching and austempered at 360℃,have been measured using specimens under four-point *** was also made of the crack path and fracture morphology with relation to *** formation of LCM/B duplex structure,which caused by 20% lower bainite after short-time isothermal treatment,may re- markably increase ΔK_(th)and considerably decrease da/*** effect of microstructure on da/dN and ΔK_(th)was discussed with the emphasis on the crack propagation path.

关键词： low carbon martensite duplex structure fatigue crack propagation rate threshold stress intensity range crack path

Online adaptive dwell scheduling based on dynamic template for PAR

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2021年第5期32卷 1119-1129页

作者： TAN Qianqian CHENG Ting li xi School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

An adaptive dwell scheduling algorithm for phased array radar(PAR)is proposed in this *** concept of online dynamic template is introduced,based on which a general pulse interleaving technique for PAR is put *** pulse interleaving condition of the novel pulse interleaving is more intuitive and *** traditional adaptive dwell scheduling algorithm combined with the general novel pulse interleaving technique results in the online adaptive dwell scheduling based on dynamic template for PAR is *** proposed algorithm is suitable for radar tasks with multiple pulse repetition intervals(PRIs),which can be utilized in the actual radar *** the purpose of further improving the scheduling efficiency,an efficient version is *** results demonstrate the effectiveness of the proposed algorithm and the efficient *** proposed efficient algorithm can improve the time utilization ratio(TUR)by 9%,the hit value ratio(HVR)by 3.5%,and reduce the task drop ratio(TDR)by 6%in comparison with existing dwell scheduling algorithms considering pulse interleaving in PAR and the proposed efficient one.

关键词： dynamic template dwell scheduling pulse interleaving