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InvesInvestigation of the Effects of Airfoil-probes on the Aerodynamic Performance of an Axial Compressor

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Chinese Journal of Aeronautics 2012年第4期25卷 517-523页

作者： HE xiang MA Hongwei REN Minglin xiang Honghui National Key Laboratory of Science and Technology on Aero-Engines School of Jet Propulsion Beihang University Beijing 100191 China China Gas Turbine Establishment Chengdu 621703 China

In order to investigate the effects of the airfoil-probes on the aerodynamic performance of an axial compressor,a numerical simulation of 3D flow field is performed in a 1.5-stage axial compressor with airfoil-probes installed at the stator leading-edge（LE）.The airfoil-probes have a negative influence on the compressor aerodynamic performance at all operating points.A streamwise vortex is induced by the airfoil-probe along both sides of the *** the mid-operating point,the vortex is notable along the pressure side and is relatively small along the suction side（SS）.At the near-stall point,the vortex is slightly suppressed in the pressure surface（PS）,but becomes remarkable in the suction side.A small local-separation is induced by the interactions between the vortex and the end-wall boundary layer in the corner region near the *** the positive pitch angle of the airfoil-probe at 6.5% span is about 15° plays an important role in the vortex evolution near the hub,which causes the fact that the airfoil-probe near the hub has the largest effects among the four *** order to get a further understanding of the vortex evolution in the stator in the numerical simulation,a flow visualization experiment in a water tunnel is *** flow visualization results give a deep insight into the evolution of the vortex induced by the airfoil-probe.

关键词： transonic compressor airfoil-probe numerical simulation flow visualization streamwise vortex disturbance

Knowledge Map： Mathematical Model and Dynamic Behaviors

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Journal of Computer Science & Technology 2005年第3期20卷 289-295页

作者： HaiZhuge xiang-FengLuo ChinaKnowledgeGridResearchGroup KeyLabofIntelligentInformationProcessingInstituteofComputingTechnologyChineseAcademyofSciencesBeijing100080P.R.China

Knowledge representation and reasoning is a key issue of the Knowledge Grid. This paper proposes a Knowledge Map (KM) model for representing and reasoning causal knowledge as an overlay in the Knowledge Grid. It extends Fuzzy Cognitive, Maps (FCMs) to represent and reason not only simple cause-effect relations, but also time-delay causal relations, conditional probabilistic causal relations and sequential relations. The mathematical model and dynamic behaviors of KM are presented. Experiments show that, under certain conditions, the dynamic behaviors of KM can translate between different states. Knowing this condition, experts can control or modify the constructed KM while its dynamic behaviors do not accord with their expectation. Simulations and applications show that KM is more powerful and natural than FCM in emulating real world.

关键词： knowledge representation causal relation fuzzy cognitive maps knowledge grid

Coronarenes: recent advances and perspectives on macrocyclic and supramolecular chemistry

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Science China Chemistry 2018年第8期61卷 993-1003页

作者： Mei-xiang Wang MOE Key Laboratory of Bioorganic Phosphorous Chemistry & Chemical Biology Department of Chemistry Tsinghua University

Synthetic macrocyclic host molecules always play an essential role in the establishment and development of supramolecular chemistry. Along with the continuous interests in the study of classical macrocycles, recent decades have witnessed the emergence and rapid development of the chemistry and supramolecular chemistry of novel and functional macrocycles. Owing to their easy availability, a self-tunable V-shaped cavity resulted from 1,3-alternate conformation, and diversified electronic features steered by the interplay between heteroatom linkages and aromatic rings, heteracalixaromatics act as a type of versatile and powerful macrocyclic hosts in molecular recognition and fabrication of supramolecular systems. Very recently, by means of engineering the bond connectivity or the recombination of chemical bonds within heteracalixaromatics, we have devised coronarenes, a new generation of macrocycles. In this concise review, macrocyclic and supramolecular chemistry of coronarenes are summarized in the order of their syntheses, structural features, molecular recognition and self-assembly properties. In the last part of this article, personal perspectives on the study of macrocyclic and supramolecular chemistry will also be discussed.

关键词： coronarenes heteracalixaromatics macrocycles molecular recognition non-covalent bond interactions

Electronic Structure and Magnetic Properties of Rh_(13) Cluster with Three Possible Symmetries

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Chinese Journal of Structural Chemistry 2006年第6期25卷 667-672页

作者： KUANG xiang-Jun School of Science Southwest University of Science and Technology Mianyang Sichuan 621010 China

Electronic and magnetic properties of 13-atom Rh clusters with three possible high symmetry geometries have been studied by using the first-principles DV-LSD method. An anomalous symmetry dependence of the cluster magnetism was found that the total magnetic moment of the icosahedral Rh13 cluster is smaller than that of the other two lower-symmetry clusters in a wide range of interatomic spacings. An energy difference is identified to explain this anomalous relationship, which has been found to be also useful for judging whether the broadening technique is correctly used and whether multiple input potentials must be used to reach the actual ground state in the LSD calculations. The calculated results are compared and discussed with those of previous theory and recent experiment. The actual geometry of the Rh13 cluster is suggested to be a distorted icosahedron.

关键词： Rh13 clusters electronic structure magnetic properties three possible symmetries

A NEW STEPSIZE FOR THE STEEPEST DESCENT METHOD

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Journal of Computational Mathematics 2006年第2期24卷 149-156页

作者： Ya-xiang Yuan LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

The steepest descent method is the simplest gradient method for optimization. It is well known that exact line searches along each steepest descent direction may converge very slowly. An important result was given by Barzilar and Borwein, which is proved to be superlinearly convergent for convex quadratic in two dimensional space, and performs quite well for high dimensional problems. The BB method is not monotone, thus it is not easy to be generalized for general nonlinear functions unless certain non-monotone techniques being applied. Therefore, it is very desirable to find stepsize formulae which enable fast convergence and possess the monotone property. Such a stepsize αk for the steepest descent method is suggested in this paper. An algorithm with this new stepsize in even iterations and exact line search in odd iterations is proposed. Numerical results are presented, which confirm that the new method can find the exact solution within 3 iteration for two dimensional problems. The new method is very efficient for small scale problems. A modified version of the new method is also presented, where the new technique for selecting the stepsize is used after every two exact line searches. The modified algorithm is comparable to the Barzilar-Borwein method for large scale problems and better for small scale problems.

关键词： Steepest descent Line search Unconstrained optimization Convergence.

Gamma-Ray Bursts Subset and Supernova Remnants Low Radio-Frequency Turnover

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Chinese Physics Letters 2000年第8期17卷 623-624页

作者： LIU xiang Urumqi Astronomical Observatory National Astronomical ObservatoriesChinese Academy of SciencesUrumqi 830011

Durations of gamma-ray bursts(GRB's)are featured by>2s subset and<2s one,with initial corresponding energy ratio being 20:*** is found that supernova remants(SNR's)turnover frequencies peak at 100 and 500 *** assuming that GRB's originate from hypernova and making an analysis on the evolution of GRB's,we find that the initial energy of two GRB subsets leads to a different radio-frequency turnover of their remnant spectra,which accords positively with the turnover-frequency ratio of SNR's.

关键词： evolution supernova initial

Detection and Estimation of False Data Injection Attacks for Load Frequency Control Systems

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Journal of Modern Power Systems and Clean Energy 2022年第4期10卷 861-870页

作者： Jun Ye xiang Yu Hangzhou Innovation Institute Beihang UniversityHangzhouChina School of Automation Science and Electrical Engineering Beihang UniversityBeijingChina

False data injection attacks(FDIAs)against the load frequency control(LFC)system can lead to unstable operation of power *** this paper,the problems of detecting and estimating the FDIAs for the LFC system in the presence of external disturbances are ***,the LFC system model with FDIAs against frequency and tie-line power measurements is ***,a design procedure for the unknown input observer(UIO)is presented and the residual signal is generated to detect the *** UIO is designed to decouple the effect of the unknown external disturbance on the residual *** that,an attack estimation method based on a robust adaptive observer(RAO)is proposed to estimate the state and the FDIAs *** order to improve the performance of attack estimation,the H¥technique is employed to minimize the effect of external disturbance on estimation errors,and the uniform boundedness of the state and attack estimation errors is proven using Lyapunov stability ***,a two-area interconnected power system is simulated to demonstrate the effectiveness of the proposed attack detection and estimation algorithms.

关键词： External disturbance false data injection attacks load frequency control robust adaptive observer unknown input observer

High durable aqueous zinc ion batteries by synergistic effect of V_(6)O_(13)/VO_(2) electrode materials

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Journal of Energy Chemistry 2023年第12期87卷 334-341,I0009页

作者： Yi Liu xiang Wu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870LiaoningChina

Vanadium oxides have attracted one’s wide attention due to their diverse valences and spatial structure as cathode for aqueous zinc ion ***,a strong electrostatic interaction exists between Zn ions and host materials,which leads to their sluggish reaction kinetics and inferior structural ***,we design a kind of vanadium-based electrode materials with abundant phase boundaries and oxygen *** assembled Zn//V_(6)O_(13)/VO_(2) batteries deliver a specific capacity of 498.3 mA h g^(-1)at 0.2 A g^(-1) and retain a capacity of 485.8 mA h g^(-1)after 100 ***,they achieve a retention rate of 96.8% after 5000 cycles at 10 A g^(-1).The soft pack cells also show excellent mechanical stability at different folding conditions.

关键词： Aqueous zinc ion batteries Vanadium oxide Cathode material Phase boundary Cycling stability

A Voronoi diagram approach for detecting defects in 3D printed fiber-reinforced polymers from microscope images

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Computational Visual Media 2023年第1期9卷 41-56页

作者： xiang Li Sara McMains University of California Berkeley BerkeleyCalifornia94720USA

Fiber-reinforced polymer(FRP)composites are increasingly popular due to their superior strength to weight *** contrast to significant recent advances in automating the FRP manufacturing process via 3D printing,quality inspection and defect detection remain largely manual and *** this paper,we propose a new approach to automatically detect,from microscope images,one of the major defects in 3D printed FRP parts:fiber-deficient areas(or equivalently,resin-rich areas).From cross-sectional microscope images,we detect the locations and sizes of fibers,construct their Voronoi diagram,and employ-shape theory to determine fiber-deficient *** Voronoi diagram and-shape construction algorithms are specialized to exploit typical characteristics of 3D printed FRP parts,giving significant efficiency *** algorithms robustly handle real-world inputs containing hundreds of thousands of fiber cross-sections,whether in general or non-general position.

关键词： 3D printing(3DP) microscope image processing fiber-reinforced polymer(FRP) Voronoi diagrams -shapes resin-rich areas