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A Biomimetic Rotor-configuration Design for Optimal Aerodynamic Performance in Quadrotor Drone

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Journal of Bionic Engineering 2021年第4期18卷 824-839页

作者： Yi Li Koichi Yonezawa ru xu Hao Liu Graduate School of Engineering Chiba University1-33 Yayoi-choInage-kuChiba263-8522Japan Central Research Institute of Electric Power Industry Civil Engineering Research Laboratory1646 AbikoAbiko-shi270-1194Japan

Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration design to explore optimal aerodynamic performance in multirotor *** aerodynamic interactions among propellers in multirotor Unmanned Aerial Vehicles(UAVs)play a crucial role in lift force production and Figure of Merit(FM)efficiency,the rotor-configuration effect remains poorly *** we address a Computational Fluid Dynamics(CFD)-based study on optimal aerodynamic performance of the rotor-configuration in hovering quadrotor drones with a specific focus on the aerodynamic effects of tip distance,height difference and tilt angle of *** results indicate that the tip distance-induced interactions can most alter lift force production and hence lead to remarked improvement in FM,and the height difference also plays a key role in improving aerodynamic performance,while the tilt angle effect is less ***,we carried out an extensive analysis to explore the optimal aerodynamic performance of the rotor-configuration over a broad parameter space,by combining the CFD-based simulations and a novel surrogate *** find that a rotor-configuration with a large tip distance and some height difference with zero tilt angle is capable of optimizing both lift force production and FM,which could offer a novel optimal design as well as maneuver strategy for multirotor UAVs.

关键词： bioinspiration optimal quadrotor configuration aerodynamic interactions aerodynamic performance CFD surrogate modeling

Stability of Weak Solutions for the Compressible Navier-Stokes-Poisson Equations

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Acta Mathematicae Applicatae Sinica 2012年第3期28卷 597-606页

作者： ru-xu LIAN Ming-jie LI College of Mathematics and Information Science North China University of Water Resources and Electric PowerZhengzhou 450011China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

In this paper, we consider the isentropic compressible Navier-Stokes-Poisson equations arising from transport of charged particles or motion of gaseous stars in astrophysics. We are interested in the case that the viscosity coefficients depend on the density and shall degenerate in the appearance of （density） vacuum, and show the Ll-stability of weak solutions for arbitrarily large data on spatial multi-dimensional bounded or periodic domain or whole space.

关键词： compressible fluid Navier-Stokes-Poisson equations stability

Free Boundary Value Problem for the Cylindrically Symmetric Compressible Navier-Stokes Equations with a Constant Exterior Pressure

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 761-774页

作者： ru-xu LIAN Jun-li WANG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Guanghua School of Management Peking University Beijing 100871 China

This paper is concerned with the free boundary value problem（FBVP） for the cylindrically symmetric barotropic compressible Navier-Stokes equations（CNS） with density-dependent viscosity coefficients in the case that across the free surface stress tensor is balanced by a constant exterior pressure. Under certain assumptions imposed on the initial data, the unique cylindrically symmetric strong solution is shown to exist globally in time and tend to a non-vacuum equilibrium state exponentially as time tends to infinity.

关键词： Navier-Stokes equations cylindrically symmetric density-dependent viscosity coefficients con-stant exterior pressure strong solution

Hydrothermal Synthesis and Characterization of Perovskite PbTiO_(3) Powders from Different Precursors

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Chemical Research in Chinese Universities 1998年第3期14卷 3-7页

作者： CHEN Dai-rong xu ru-ren Department of Chemistry Jilin UniversityChangchun130023

Perovskite type of PbTiO 3 fine powders which are homogeneous in physic chemical properties has been hydrothermally synthesized from the different precursors. The borderline reaction conditions, such as temperature and time, for the formation of PbTiO 3 were established and the effect of the precursor on the particle properties was investigated. As a precursor, Pb Ti alko carbonate xerogel dispersed in 2 methoxyethanol was found to be effective for the synthesis of the PbTiO 3 powders with a lower agglomeration and a simple mode of particle size.

关键词： Hydrothermal synthesis PbTiO 3 powders Precursor

On-chip boost regulator with projected off- and on-time control

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第8期10卷 1223-1230页

作者： Xiao-ru xu Meng-lian ZHAO Xiao-bo WU Institute of VLSI Design Zhejiang University Hangzhou 310027 China

The boost type power supplies are widely used in portable consumer electronics to step up the input voltage to adapt for the high voltage applications like light-emitting diode(LED) driving and liquid crystal display(LCD) *** these applications,a regulator with small volume,fewer external components and high efficiency is highly *** paper proposes a projected off-and on-time boost control scheme,based on which a monolithic IC with an on-chip VDMOS with 0.2 Ω on-state resistance RDS-ON was implemented in 1.5 μm bipolar-CMOS-DMOS(BCD) process.A 12 V,0.3 A boost regulator prototype is presented as *** projected off-time and modulated on-time in continuous conduction mode(CCM),a quasi fixed frequency,which is preferred for ripple control,is *** projected on-time and modulated off-time in discontinuous conduction mode(DCM),pulse frequency modulation(PFM) operation,which is beneficial to light load efficiency improvement,is achieved without extra control *** results show that an efficiency of 3% higher than that of a conventional method under 0.5 W output is achieved while a step load transient response comparable to that of current mode control is maintained as well.

关键词： Boost regulator Integrated circuits Pulse frequency modulation Projected off-time Projected on-time

Load balancing routing for single-layered satellite networks

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The Journal of China Universities of Posts and Telecommunications 2010年第2期17卷 92-99页

作者： RAO Yuan WANG ru-chuan xu Xiao-long College of Computer Nanjing University of Posts and Telecommunications Nanjing 210003 China

The varying population density leads to imbalanced utilization rate of satellites. To ensure an intelligent engineering of traffic over satellite networks, a distributed routing scheme for single-layered satellite network, load balancing routing protocol based on mobile agent （LBRP-MA） is proposed. For LBRP-MA, mobile agents explore route by migrating autonomously. Upon arriving at destination, mobile agents migrate back. On each intermediate satellite, mobile agents evaluate path cost considering satellite geographical position as well as inter-satellite link （ISL） cost, and finally take ISL congestion index into account to update routing tables. Through simulations on the Courier-like constellation, the proposed approach is shown to achieve guaranteed end-to-end delay bound and decrease packet loss ratio with better throughput, which is especially suitable for data transferring in case of high traffic load. Moreover, results of the complexity analysis demonstrate that LBRP-MA can have low onboard signaling, storage and computation requirements. Furthermore, issues of LBRP-MA such as ISL congestion index and cost modification factor are discussed.

关键词： load balancing mobile agent satellite networks routing

Energetic Particle Physics on the HL-2A Tokamak: A Review

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Chinese Physics Letters 2021年第3期38卷 55-68页

作者： Pei-Wan Shi Wei Chen xu-ru Duan Southwestern Institute of Physics Chengdu 610041China Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China

Interaction between shear Alfvén wave(SAW) and energetic particles(EPs) is one of major concerns in magnetically confined plasmas since it may lead to excitation of toroidal symmetry breaking collective instabilities,thus enhances loss of EPs and degrades plasma confinement. In the last few years, Alfvénic zoology has been constructed on HL-2A tokamak and series of EPs driven instabilities, such as toroidal Alfvén eigenmodes(TAEs),revered shear Alfvén eigenmodes(RSAEs), beta induced Alfvén eigenmodes(BAEs), Alfvénic ion temperature gradient(AITG) modes and fishbone modes, have been observed and investigated. Those Alfvénic fluctuations show frequency chirping behaviors through nonlinear wave-particle route, and contribute to generation of axisymmetric modes by nonlinear wave-wave resonance in the presence of strong tearing modes. It is proved that the plasma confinement is affected by Alfvénic activities from multiple aspects. The RSAEs resonate with thermal ions, and this results in an energy diffusive transport process while the nonlinear mode coupling between core-localized TAEs and tearing modes trigger avalanche electron heat transport events. Effective measures have been taken to control SAW fluctuations and the fishbone activities are suppressed by electron cyclotron resonance heating. Those experimental results will not only contribute to better understandings of energetic particles physics, but also provide technology bases for active control of Alfvénic modes on International Thermonuclear Experimental Reactor(ITER) and Chinese Fusion Engineering Testing Reactor(CFETR).

关键词： wave transport collective

High-sensitive cardiac troponin T

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Journal of Geriatric Cardiology 2013年第1期10卷 102-109页

作者： ru-Yi xu Xiao-Fa Zhu Ye Yang Ping Ye Department of Geriatric Cardiology Navy General Hospital No.6 Fucheng Road Beijing 100048 China Department of Geriatric Cardiology Chinese PLA General Hospital No.28 Fuxing Road Beijing 100853 China

Cardiac troponin is the preferred biomarker for the diagnosis of acute myocardial infarction (AMI). The recent development of a high-sensitive cardiac troponin T (hs-cTnT) assay permits detection of very lowlevels of cTnT. Using the hs-cTnT assay improves the overall diagnostic accuracy in patientswith suspected AMI, while a negative result also has a high negative predictive value. The gain in sensitivitymay be particularly important in patientswith a short duration from symptom onset to *** of cardiac troponin T with the hs-cTnT assay may provide strong prognostic information in patients with acute coronary syndromes, stable coronary artery disease, heart failure and even in the general population; however, increased sensitivity comes at a cost of decreased specificity. Serial testing, aswell as clinical context and co-existing diseases, are likely to become increasingly important for the interpretation of hs-cTnT assay results.

关键词： Acute myocardial infarction Risk stratification Troponin T

The Syntheses of 1-Dimensional(1-D)Chain,2-D Layered,and 3-D Microporous Alumino-phosphates with Occluded Amine or Ammonium Templates from Alcoholic Systems

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Chemical Research in Chinese Universities 1997年第2期13卷 12-18页

作者： GAO Qiu ming CHEN Jie sheng xu ru ren Key Laboratory of Inorganic Synthesis and Preparative Chemistry Department of ChemistryJilin UniversityChangchun 130023

The present paper covers the syntheses of 1 D chain, 2 D layered and 3 D microporous aluminophosphates containing organic amines or ammonium in the presence of various amines from alcoholic systems. The rule for the crystallization of the above three families of microporous aluminophosphates was summarized and the effects of organic amine, P/Al ratio, sources of aluminum and phosphorous and temperature on the resulted structures were investigated.

关键词： Aluminophosphate template Alcoholic system Synthesis