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Performance analysis of cognitive relay systems with spectrum- sharing interference under a primary outage probability constraint

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The Journal of China Universities of Posts and Telecommunications 2014年第1期21卷 16-21页

作者： YAN sheng-nan LI Yan College of Information Science and Engineering Yanshan University School of Information and Communication Engineering Beijing University of Posts and Telecommunications

This paper investigates the performance of an underlay cognitive relay system where secondary users（SUs） suffer from a primary outage probability constraint and spectrum-sharing interference imposed by a primary user（PU）. In particular, we consider a secondary multi-relay network operating in the selection decode-and-forward（SDF） mode and propose a best-relay selection criterion which takes into account the spectrum-sharing constraint and interference. Based on these assumptions, the closed-form expression of the outage probability of secondary transmissions is derived. We find that a floor of the outage probability occurs in high signal-to-noise ratio（SNR） regions due to the joint effect of the constraint and the interference from the PU. In addition, we propose a generalized definition of the diversity gain for such systems and show that a full diversity order is achieved. Simulation results verify our theoretical solutions.

关键词： cognitive relay systems spectrum-sharing interference outage probability diversity gain

Fluorescence detection of perfluorooctane sulfonate in water employing a tetraphenylethylene-derived dual macrocycle Bowtie Cyclophane

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Chinese Chemical Letters 2022年第3期33卷 1493-1496页

作者： sheng-nan Lei Huan Cong Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry&School of Future TechnologyUniversity of Chinese Academy of SciencesChinese Academy of SciencesBeijing 100190China

Because the widely used perfluorooctane sulfonate(PFOS) is harmful to both environment and human health, it is of great significance and urgency to develop sensitive and selective sensors for the detection of trace PFOS in water. In this study, a tetraphenylethylene-derived macrocycle Bowtie Cyclophane has been developed as a fluorescent sensor based on aggregation-induced emission enhancement and fluorochromism. Sensitive detection of PFOS has been achieved with a limit of detection(LOD) of47.3 ± 2.0 nmol/L(25.4 ± 1.1 μg/L) accompanied by visual fluorescence color changes.

关键词： Fluorescence Aggregation Perfluorooctane sulfonate Tetraphenylethylene Macrocycle

An Error Equivalent Model of Revolute Joints with Clearances for Antenna Pointing Mechanisms

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 97-105页

作者： Quan Liu sheng-nan Lu Xi-Lun Ding School of Mechanical Engineering and Automation Beihang University

Joint clearances in antenna pointing mechanisms lead to uncertainty in function deviation. Current studies mainly focus on radial clearance of revolute joints, while axial clearance has rarely been taken into consideration. In fact, own?ing to errors from machining and assembly, thermal deformation and so forth, practically, axial clearance is inevitable in the joint. In this study, an error equivalent model(EEM) of revolute joints is proposed with considering both radial and axial clearances. Compared to the planar model of revolute joints only considering radial clearance, the journal motion inside the bearing is more abundant and matches the reality better in the EEM. The model is also extended for analyzing the error distribution of a spatial dual?axis("X–Y" type) antenna pointing mechanism of Spot?beam antennas which especially demand a high pointing accuracy. Three case studies are performed which illustrates the internal relation between radial clearance and axial clearance. It is found that when the axial clearance is big enough, the physical journal can freely realize both translational motion and rotational motion. While if the axial clearance is limited, the motion of the physical journal will be restricted. Analysis results indicate that the consideration of both radial and axial clearances in the revolute joint describes the journal motion inside the bearing more precise. To further validate the proposed model, a model of the EEM is designed and fabricated. Some suggestions on the design of revolute joints are also provided.

关键词： Error modeling Joint clearances Antenna pointing mechanism Radial clearance Axial clearance

Toxic effects of perfluorononanoic acid on the development of Zebrafish(Danio rerio) embryos

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Journal of Environmental Sciences 2015年第6期27卷 26-34页

作者： Hui Liu nan sheng Wei Zhang Jiayin Dai Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology Chinese Academy of Sciences University of Chinese Academy of Sciences

Perfluorononanoic acid（PFNA） is a nine-carbon perfluoroalkyl acid widely used in industrial and domestic products. It is a persistent organic pollutant found in the environment as well as in the tissues of humans and wildlife. There is a concern that this chemical might be a developmental toxicant and teratogen in various ecosystems. In the present study,the toxic effects of PFNA were evaluated in zebrafish（Danio rerio） embryos. One hour post-fertilization embryos were treated with 0, 25, 50, 100, 200, 300, 350, and 400 μmol/L PFNA for 96 hr in 6-well plates. Developmental phenotypes and hatching rates were observed and recorded. Nineteen genes related to oxidative stress and lipid metabolism were examined using Quantitative RT-PCR and confirmed by whole mount in situ hybridization（WISH）. Results showed that PFNA delayed the development of zebrafish embryos, reduced the hatching rate, and caused ventricular edema and malformation of the spine. In addition, the amount of reactive oxygen species in the embryo bodies increased significantly after exposure to PFNA compared with that of the control group. The Quantitative RT-PCR and WISH experiments demonstrated that m RNA expression of the lfabp and ucp2 genes increased significantly while that of sod1 and mt-nd1 decreased significantly after PFNA exposure. The m RNA expression levels of gpx1 and mt-atp6 decreased significantly in the high concentration group. However, the m RNA expression levels of both ppara and pparg did not show any significant variation after exposure. These findings suggest that PFNA affected the development of zebrafish embryos at relatively low concentrations.

关键词： Perfluorononanoic acid Zebrafish embryo Danio rerio Developmental toxicity

Dynamic performance and wake structure of flapping plates with different shapes

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Acta Mechanica Sinica 2014年第6期30卷 800-808页

作者： Gao-Jin Li nan-sheng Liu Xi-Yun Lu Department of Modern Mechanics University of Science and Technology of China

The dynamic performance and wake structure of flapping plates with different shapes were studied using multi-block lattice Boltzman and immersed boundary *** typical regimes relevant to thrust behavior are *** is nonlinear relation between the thrust and the area moment of plate for lower area moment region and the other is linear relation for larger area moment *** tendency of the power variation with the area moment is reasonably similar to the thrust behavior and the efficiency decreases gradually as the area moment *** the mechanism of the dynamic properties is associated with the evolution of vortical structures around the plate,the formation and evolution of vortical structures are investigated and the effects of the plate shape,plate area,Strouhal number and Reynolds number on the vortical structures are *** results obtained in this study provide physical insight into the understanding of the mechanisms relevant to flapping locomotion.

关键词： Dynamics of flapping plate Flapping locomotion Plate shape Vortex dynamics

DIRECT NUMERICAL SIMULATION OF TURBULENT HEAT TRANSFER IN A WALL-NORMAL ROTATING CHANNEL FLOW

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Journal of Hydrodynamics 2006年第1期18卷 26-31页

作者： LI Bu-yang LIU nan-sheng LU Xi-yun Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China

Direct Nmerical Simulation （DNS） of turbulent heat transfer in a wall-normal rotating channel flow has been carried out for the rotation number Nr from 0 to 0.1, the Reynolds number 194 based on the friction velocity of non ro taring case and the half-height of the channel, and the Prandtl number 1. The objective of this study is to reveal the effects of rotation on the characteristics of turbulent flow and heat transfer. Based on the present calculated results, two typical rotation regimes are identified. When 0 〈 Nr 〈 0.06, turbu lence and thermal statistics correlated with the spanwise veloc ity fluctuation are enhanced since the shear rate of spanwise mean flow induced by Coriolis force increases; however, the other statistics are suppressed. When Nr 〉 0.06, turbulence and thermal statistics are suppressed significantly because the Coriolis force effect plays as a dominated role in the rotating flow. Remarkable change of the direction of near wall streak structures based on the velocity and temperature fluctuations is identified.

关键词： Direct Numerical Simulation (DNS) wallnormal rotating channel flow turbulent heat transfer thermal statistics

Event-based adaptive asymptotic tracking control of nonlinear time-varying systems with prescribed performance

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Journal of Control and Decision 2023年第3期10卷 355-364页

作者： sheng-nan Shi Yuan-Xin Li Department of Automation Qingdao UniversityQingdaoShandongPeople’s Republic of China Department of Science Liaoning University of TechnologyJinzhouLiaoningPeople’s Republic of China

This paper is concerned with the adaptive tracking control problem of nonlinear time-varyingsystems. Based on the backstepping technology, an event-based prescribed performance controlscheme is developed. And the time-varying uncertainties of the system are handled byutilising bound estimation method. The proposed controller not only ensures the prescribedtracking performance, but also reduces the communication burden. By using Lyapunov stabilityanalysis, it is proven that all of the closed-loop signals are bounded, and the tracking errorcan converge to zero. Simultaneously, Zeno behaviour is excluded. Finally, the simulation resultsare utilised to illustrate the effectiveness of the proposed adaptive control scheme.

关键词： Nonlinear time-varying systems event-triggered control(ETC) adaptive asymptotic tracking control prescribed performance

Responses of plant diversity and species composition to the cessation of fertilization in a sandy grassland

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Journal of Forestry Research 2014年第2期25卷 337-342页

作者： sheng-nan Shi Zhan-yuan Yu Qiong Zhao State Key Laboratory of Forest and Soil Ecology Institute of Applied Ecology Chinese Academy of Sciences University of Chinese Academy of Sciences Daqinggou Ecological Station Institute of Applied EcologyChinese Academy of Sciences

Nitrogen was the main limiting nutrient of net primary production in the southeastern Keerqin Sandy Lands, Northeast China. Species richness declined and biomass increased after five consecutive years of nitrogen fertilization of these sandy grasslands （2004-2008）. After fertilization had been stopped for three years （2009-2011）, we surveyed vegetation on previously fertilized plots to quantify changes in commu- nity composition. Respect species richness showed an increasing trend over time since the cessation of fertilization. Respect vegetation height and coverage showed decreasing trends over time since the cessation of fertilization. Species composition changed after fertilization ceased, the dominant species shifting from Cannabis sativa, Phragmites communis and Chenopodium acuminaturn in 2008 to Cannabis sativa, Phragmites communis and Artemisia scoparia in 2011. Dominance of dominant species declined from 66.2% in 2008 to 57.5% in 2011. The importance value of annual plants in the earlier nitrogen addition plots was higher than in control plots, but the differences were not significant in 2011. The importance value of perennial plants differed significantly between treatments from 2009 to 2011. The reversion rate not only differed be- tween community characteristics, but also between functional groups in the same community characteristic. Although the residual effect of nitrogen addition on vegetation was still observed three years after fertilization ceased, the vegetation showed signs of recovery.

关键词： nitrogen fertilization recovery Keerqin Sandy Lands vegetation

High‑Performance Fasciated Yarn Artificial Muscles Prepared by Hierarchical Structuring and Sheath-Core Coupling for Versatile Textile Actuators

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Advanced Fiber Materials 2023年第4期5卷 1534-1547页

作者： nan sheng Yangyang Peng Fengxin Sun Jinlian Hu MOE Key Laboratory of Eco‑Textiles Jiangnan UniversityWuxi 214122China Department of Biomedical Engineering City University of Hong KongHong Kong S.A.R 999077China

High-performance yarn artificial muscles are highly desirable as miniature actuators,sensors,energy harvesters,and soft ***,achieving a yarn artificial muscle that covers all the properties of excellent actuation performance,mechanical robustness,structural stability,and high scalability by a low-cost strategy is still a great ***,a bio-inspired fasciated yarn structure is first reported for creating robust high-performance yarn artificial *** conventional strategies that leverage costly materials or complex processing,the developed yarn artificial muscles are constructed by hierarchically helical and sheath-core assembly design of cost-effective common fibers,such as viscose and *** hierarchically helical sheath structure pushes the theoretical limit of the inserted twist in yarns and endows the yarn muscles with large stroke(5815°cm^(-1))and high work capacity(23.5 J kg^(-1)).Due to the rapid water transfer and efficient energy conversion of inter-sheath-core coupling,the as-prepared yarn muscles possess fast response,high rotation accelerated speed,and low recovery ***,the inactive core yarn serves as support for internal tethering and load-bearing,enabling these yarn muscles to maintain a self-stable structure,robust life cycle and *** show that the yarn muscle fabricated in this method is readily available and highly scalable for achieving high-dimensional actuation deformations,which considerably broadens the application scenarios of artificial muscles.

关键词： Artificial muscles Hierarchical structuring Actuators Smart textiles