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Accurately tracking hypersonic gliding vehicles via an LEO mega-constellation in relay tracking mode

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Journal of Systems Engineering and Electronics 2024年第1期35卷 211-221页

作者： li Zhao WANG Yidi ZHENG wei College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In order to effectively defend against the threats of the hypersonic gliding vehicles(HGVs),HGVs should be tracked as early as possible,which is beyond the capability of the ground-based *** benefited by the developing megaconstellations in low-Earth orbit,this paper proposes a relay tracking mode to track HGVs to overcome the above *** whole tracking mission is composed of several tracking intervals with the same *** each tracking interval,several appropriate satellites are dispatched to track the *** that are planned to take part in the tracking mission are selected by a new derived observability *** tracking performances of the proposed tracking mode and the other two traditional tracking modes,including the stare and track-rate modes,are compared by *** results show that the relay tracking mode can track the whole trajectory of a HGV,while the stare mode can only provide a very short tracking ***,the relay tracking mode achieve higher tracking accuracy with fewer attitude controls than the track-rate mode.

关键词： target tracking mega-constellation hypersonic gliding vehicle(HGV) sensor selection observability analysis

Comprehensive Evaluation Method for Traffic Flow Data Quality Based on Grey Correlation Analysis and Particle Swarm Optimization

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 106-128页

作者： wei Ba Baojun Chen Qi li School of Automation and Electrical Engineering Dalian Jiaotong UniversityDalian116028China Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian116023China

Nowadays,data are more and more used for intelligent modeling and prediction,and the comprehensive evaluation of data quality is getting more and more attention as a necessary means to measure whether the data are usable or ***,the comprehensive evaluation method of data quality mostly contains the subjective factors of the evaluator,so how to comprehensively and objectively evaluate the data has become a bottleneck that needs to be solved in the research of comprehensive evaluation *** order to evaluate the data more comprehensively,objectively and differentially,a novel comprehensive evaluation method based on particle swarm optimization(PSO)and grey correlation analysis(GCA)is presented in this *** first,an improved GCA evaluation model based on the technique for order preference by similarity to an ideal solution(TOPSIS)is ***,an objective function model of maximum difference of the comprehensive evaluation values is built,and the PSO algorithm is used to optimize the weights of the improved GCA evaluation model based on the objective function ***,the performance of the proposed method is investigated through parameter analysis.A performance comparison of traffic flow data is carried out,and the simulation results show that the maximum average difference between the evaluation results and its mean value(MDR)of the proposed comprehensive evaluation method is 33.24%higher than that of TOPSIS-GCA,and 6.86%higher than that of *** proposed method has better differentiation than other methods,which means that it objectively and comprehensively evaluates the data from both the relevance and differentiation of the data,and the results more effectively reflect the differences in data quality,which will provide more effective data support for intelligent modeling,prediction and other applications.

关键词： Data quality comprehensive evaluation particle swarm optimization grey correlation analysis traffic flow data

The First Five Years of a Phase Theory for Complex Systems and Networks

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1728-1743页

作者： Dan Wang wei Chen li Qiu Division of Decision and Control Systems KTH Royal Institute of TechnologyStockholm 10044Sweden Department of Mechanics and Engineering Science&the State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing 100871China Hong Kong University of Science and Technology Hong KongChinaand also with the Southern University of Science and TechnologyShenzhen 518055China

In this paper,we review the development of a phase theory for systems and networks in its first five years,represented by a trilogy:Matrix phases and their properties;The MIMO LTI system phase response,its physical interpretations,the small phase theorem,and the sectored real lemma;The synchronization of a multi-agent network using phase *** the end,we also summarize a list of ongoing research on the phase theory and speculate what will happen in the next five years.

关键词： Consensus and synchronization matrix phases multi-agent systems phase theory sectored real lemma small phase theorem.

Scattering of Water Waves by Dual Symmetric Inclined Floating Porous Barriers Using the DBEM

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China Ocean Engineering 2024年第1期38卷 156-168页

作者： WANG li-xian DENG Yan-wen YE Yang-sha DENG Zheng-zhi Key Laboratory of High Performance Ship Technology(Wuhan University of Technology) Ministry of EducationWuhan 430063China School of Naval Architecture Ocean and Energy Power EngineeringWuhan University of TechnologyWuhan 430063China Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province Changsha 410114China Institute of Port Coastal and Offshore EngineeringZhejiang UniversityZhoushan 316021China

The scattering of normally incident water waves by two surface-piercing inclined perforated barriers in water with a uniform finite depth is investigated within the framework of linear water wave *** that thin barriers are zero-thickness,a novel numerical method involving the the coupling of the dual boundary element method(DBEM)with damping layers is *** order to effectively damp out the reflected waves,two damping layers,instead of pseudoboundaries are implemented near the two side boundaries of the computational ***,the modified linearized free surface boundary conditions are formulated and used for solving both the ordinary boundary integral equation as well as the hypersingular boundary integral equation for degenerate *** newly developed numerical method is validated against analytical methods using the matched eigenfunction expansion method for the special case of two vertical barriers or the inclined angle to the vertical being *** influence of the length of the two damping layers has been ***,these findings are also validated against previous results for several *** validation,the numerical results for the reflection coefficient,transmission coefficient and dissipation coefficient are obtained by varying the inclination angle and porosity-effect *** effects of both the inclination angle and the porosity on the amplitudes of wave forces acting on both the front and rear barriers are also *** is found that the effect of the inclination angle mainly shifts the location of the extremal values of the reflection and the transmission ***,a moderate value of the porosity-parameter is quite effective at dissipating wave energy and mitigating the wave loads on dual barriers.

关键词： dual boundary element method inclined perforated floating breakwater reflection coefficient transmission coefficient damping layer

Highly Improved Creep Resistance in Polypropylene Through Thermally Reduced Graphene Oxide and Its Creep lifetime Prediction

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Chinese Journal of Polymer Science 2024年第2期42卷 256-266,I0010页

作者： Can-Can Zhang Jun-Long Yang Ya-Jiang Huang Guang-xian li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu610065China

Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.

关键词： Thermally reduced graphene oxide Polypropylene Creep failure and lifetime prediction

A Two-stage Service-oriented Task Offloading Framework with Edge-cloud Collaboration:A Game Theory Approach

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Journal of Systems Science and Systems Engineering 2024年第5期33卷 521-551页

作者： Shiyong li Wenzhe li Huan liu wei Sun School of Economics and Management Yanshan UniversityQinhuangdao 066004

With the fast development of Mobile Internet,data traffic generated by end devices is anticipated to witness substantial growth in the future ***,processing tasks locally will cause latency due to the limited resources of the end ***-cloud collaboration,an effective solution for latency-sensitive applications,is attracting greater attention from both industry and *** combines the advantages of the cloud center with abundant computing resources and edge nodes with low-latency *** this paper,we propose a two-stage task offloading framework with edge-cloud collaboration to assist end devices processing latency-sensitive tasks either on the edge servers or in the cloud *** for homogeneous task offloading,in the first stage,the competitive end devices offload tasks to the edge *** formulate the selfish task offloading problem among end devices as a potential *** the second stage,the edge nodes request resources from the cloud center to process end devices tasks due to their limited ***,we consider the heterogeneous task offloading problem and use intelligent optimization algorithm to obtain the optimal offloading *** results show that the service prices of edge nodes influence the decisions and task offloading costs of end *** also verify the intelligent optimization algorithm can achieve optimal performance with low complexity and fast convergence.

关键词： Edge-cloud collaboration task offloading potential game simulation annealing algorithm

Non-innocent partners:bias distribution between photoanodes and cathodes in photoelectrochemical overall water-splitting cells

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National Science Review 2024年第06期11卷 88-89页

作者： wei li Dunwei Wang Department of Chemistry Merkert Chemistry Center Boston College

Photoelectrochemical (PEC) overall water splitting (OWS) represents a highly promising strategy to directly harvest solar energy and store it in the form of fuels,offering unique benefits such as mitigating issues con...

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Dynamic Measurement of Intracellular pH Based on Bioluminescent Bacteria

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Chemical Research in Chinese Universities 2024年第2期40卷 287-292页

作者： li Yaohua WANG wei State Key Laboratory of Analytical Chemistry for life Science School of Chemistry and Chemical EngineeringChemBIC(Chemistry and Biomedicine Innovation Center)Nanjing UniversityNanjing210023P.R.China

Intracellular pH(pHi)is a fundamental indicator of cellular physiological state,regulating cellular state and function,and has important research *** various probes for measuring intracellular pH were available,it is challenging to reflect pHi in real-time and reversible ***,we developed a whole-cell bioluminescent(BL)probe based on wild type BL bacteria,photobacterium phosphoreum(***),to determine and image *** dependence of BL intensity of *** on pH values of culture solutions was *** was found that BL intensity could respond to the change of pH values rapidly and *** further revealed that *** maintained pH homeostasis in the extracellular pH(pHe)within the range of 5.0–7.0,while intracellular pH homeostasis was destroyed at the alkaline *** method opens up the enormous potential of BL bacteria as an alternative to fluorescence for monitoring and imaging pHi.

关键词： Bioluminescence P.phosphoreum Intracellular pH Cell imaging

Factors influencing the functional significance in intermediate coronary stenosis

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Journal of Geriatric Cardiology 2015年第2期12卷 107-112页

作者： li-Jie SUN Gui-Song WANG Ming CUI li-Jun GUO Yong-Zhen ZHANG Fu-Chun ZHANG Jie NIU Jiang-li HAN wei-xian XU Dan ZHU wei GAO Department of Cardiology Peking University Third Hospital 49 North Huayuan Road Haidian D&trict Beijingl O0191 China

Objective To analyze the influencing factors of the functional significance determined by fractional flow reserve （FFR） in interme- diate coronary artery stenosis. Methods The study enrolled 143 patients with 203 intermediate coronary lesions. Pressure-derived FFR of these lesions was gained at maximal hyperemia induced by intravenous adenosine infusion. An FFR 〈 0.80 was considered as abnormal functional significance. Anatomic parameters at the lesion sites were obtained by off-line quantitative coronary angiography analysis （QCA）. The predictive value of the demographic characteristics and anatomic parameters for FFR in these intermediate lesions was assessed using multiple linear and binary logistic regression analysis. Results Overall, FFR 〈 0.8 was found in 70 （34%） of the total 203 intermediate coronary lesions. FFR values were positively correlated with QCA-measured minimum lumen diameters （MLD, r = 0.372, P = 0.000） and the reference vessel diameters （RVD, r = 0.217, P〈 0.002） were negatively correlated with percent area stenosis （AS, r = -0.251, P = 0.000） and percent diameter stenosis （DS, r = -0.210, P = 0.000）. Age, MLD and the lesion location in different coronary arteries were the inde- pendent determinants of FFR 〈 0.8. Conclusions MLD can predict the functional significance of intermediate coronary stenosis, while age and the lesion location in different coronary arteries should be taken into account as important influencing factors of FFR values.

关键词： Fractional flow reserve Influencing factors Intermediate coronary lesion Quantitative coronary angiography