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Druse Calcite Crystals Formed by Mesoproterozoic Paleo-Earthquake Activity in the Northern Margin of the North china Craton

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Journal of Earth Science 2024年第2期35卷 514-524页

作者： Yueshuang du Zhiguang Zhou Guosheng Wang Chen Wu Wenchao xu School of Earth sciences and Resources China University of GeosciencesBeijing100083China Key Laboratory of Continental Collision and Plateau Uplift Institute of Tibetan Plateau Researchand Center for Excellence in Tibetan Plateau Earth SciencesChinese Academy of SciencesBeijing100101China No.1 Institute of Geological and Mineral Resources Survey Henan Bureau of Geo-Exploration&Mineral DevelopmentLuoyang471000China

The Meso-neoproterozoic Bayan Obo rift is located along the northern margin of the North china Craton,and was associated with the break-up of the Columbia *** rift evolution,syn-sedimentary deformation occurred due to tectonic activity and *** events are recorded in the Jianshan Formation of the Bayan Obo Group,Inner Mongolia,as soft sediment deformation structures in the central Bayan Obo *** calcite crystals and collapse breccias in the Jianshan Formation may provide information on the rift *** druse calcite crystals are idiomorphic-columnar in shape and associated with graphite,pyrite,and quartz.δ^(13)C values of the graphite are−20‰,indicative of biogenic deoxygenation and formation in *** druse calcite crystals are inorganic in origin and formed in water at a temperature of 55℃,based on calciteδ^(13)C andδ^(18)O *** calcite grew in paleo-caves containing fault breccias,with heat derived from *** such,the druse calcite crystals are important evidence for seismic *** collapse breccias(i.e.,fault breccias)and other indicators of slip show that displacement occurred from NE to SW,which is different from the paleocurrent direction in the Jianshan *** thickness of the collapse breccia is∼200 m,which represents the height of the fault *** strike of the fault scarp was NE-SW,based on the distribution of the collapse *** Bayan Obo and Yanliao rifts experienced rapid NW-SE extension,and developed similar deformation structures at ca.1.6 Ga related to break-up of the Columbia supercontinent.

关键词： North china Craton druse calcite crystals paleo-earthquake activity collapse breccia Bayan Obo rift Proterozoic

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Air-source heat pump coupled with economized vapor injection scroll compressor and ejector:Design and experimental research

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Science china(Technological sciences) 2010年第3期53卷 782-788页

作者： xu Shuxue&MA GuoYuan beijing university of technology,beijing 100124,china beijing university of technology

Ejector can utilize high pressure energy from liquid mechanism,it can be used in heat pump system coupled with economized vapor injection(EVI)scroll *** running under low temperature conditions,the performance of the EVI system with ejector can be improved *** this paper,the design method of the heat pump system with ejector is presented,and the process for designing the heat pump with ejector(EVIe)was *** prototype heat pump was designed under the condition of the evaporation temperature of -20oC,and an experimental setup was established to test the *** measured results demonstrated that the heating EER(energy efficiency ratio)of the EVIe could reach about 4%higher than that of the system without the ejector when the heating capacity remained nearly *** design method is helpful to development of a heat pump system coupled with scroll compressor and ejector.

关键词： heat pump ejector design scroll compressor

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Unsteady aerodynamic noise prediction of contra-rotating open rotor using meshless method

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Chinese Journal of Aeronautics 2024年第8期37卷 144-165页

作者： Zhiliang HONG Meng SU Haitao ZhanG Zerui xu Lin du Lingfeng CHEN college of Safety Science and Engineering Civil Aviation University of ChinaTianjin 300300China Civil Aviation Administration of china Beijing 100710China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

The Contra-Rotating Open Rotor(CROR)design confronts significant noise challenges despite being one of the possible options for future green *** efficiently estimate the noise emitted from a CROR,a three-dimensional unsteady prediction model based on the meshless method is *** unsteady wake flow and the aerodynamic load fluctuations on the blade are solved through the viscous vortex particle method,the blade element momentum theory and vortex lattice ***,the acoustic field is obtained through the Farassat’s formulation *** of this method is conducted on a CROR,and a mesh-based method,e.g.,Nonlinear Harmonic(NLH)method,is also employed for *** is found that the presented method is three times faster than NLH method while maintaining a comparable precision.A thorough parametric analysis is also carried out to illustrate the effects of rotational speed,rotor-rotor spacing and rear rotor diameter on the noise *** rotor speed is found to be the most influencing factor,and by optimizing the speed difference between the front and rear rotors,a notable noise reduction can be *** current findings not only contribute to a deeper comprehension of the CROR’s aeroacoustic properties but also offer an effective tool for engineering applications.

关键词： Contra-Rotating Open Rotor(CROR) Aerodynamic noise Blade element momentum theory Viscosity vortex particle method Farassat’s formulation 1A

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Numerical analysis on seismic response and failure mechanism of articulated pile−structure system in a liquefiable site from shaking-table experiments

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1117-1133页

作者： Pengfei DOU Hao LIU Chengshun xu Jinting WANG Yilong SUN Xiuli du Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

This study investigates the seismic response and failure mode of a pile-structure system in a liquefiable site by employing a numerical simulation model combined with the shaking-table results of a soil-pile-structure dynamic *** pile and soil responses obtained from the numerical simulations agreed well with the experimental *** slopes of the dynamic shear-stress-shear-strain hysteretic curves at different positions also exhibited a decreasing trend,indicating that the shear strength of the soil in all parts of the foundation *** peak acceleration of the soil and pile was not clearly amplified in the saturated sand layer but appeared to be amplified in the top *** maximum bending moments appeared in the middle and lower parts of the pile shaft;however,the shear forces at the corresponding positions were not *** can be observed from the deformation mode of the pile-group foundation that a typical bending failure is caused by an excessive bending moment in the middle of the pile shaft if the link between the pile top and cap is articulated,and sufficient attention should be paid to the bending failure in the middle of the pile shaft.

关键词： numerical simulation soil liquefaction pile foundation shaking-table experiment seismic responses failure model

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Designing gradient nanograined dual-phase structure in duplex stainless steel for superior strength-ductility synergy

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Journal of Materials Science & technology 2024年第3期170卷 122-128页

作者： Songsong xu Ying han Jiapeng Sun Guoqing Zu Mingkun Jiang Weiwei Zhu xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun 130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun 130012China Provincial Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of TechnologyChangchun 130012China college of Mechanics and Materials Hohai UniversityNanjing 211100China

Similar to other metallic materials,duplex stainless steel dramatically loses its advantage of high ductility as they are ***,we produce a gradient nanograined dual-phase structure in the 2101 duplex stainless steel,thus facilitating a superior strength-ductility synergy:a yield strength of 1009.5 MPa being two times higher than that of the as-received sample,a total elongation of 23.4%and a uniform elongation of 5.9%.This novel structure is produced through a processing route of ultrasonic severe surface rolling and annealing,which realizes a superposition of gradient nanostructure and lamellar dual-phase structure with austenite and *** the tension deformation of gradi-ent nanograined dual-phase structured duplex stainless steel,a significant accumulation of geometrically necessary dislocations *** dislocations are formed to accommodate the deformation incompat-ibility caused by the layer-by-layer difference in strength and hardness of individual phase domains,as well as the inherent difference in properties between the austenite and ferrite *** results in a stronger hetero-deformation induced strengthening and hardening significantly contributing to superior mechanical *** study provides a new avenue to develop advanced steels with high strength and ductility.

关键词： Gradient structure duplex stainless steel Synergetic strengthening Strength ductility

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Insights into thermodynamic performance of a hypersonic precooled air-breathing engine with a complicated multi-branch closed cycle

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Chinese Journal of Aeronautics 2024年第8期37卷 106-123页

作者： Yifan WANG Zhengping ZOU Pengcheng du Lichao YAO Huoxing LIU Yusen xu Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and technology on Aero-Engine and Aero-Thermodynamics Beihang UniversityBeijing 102206China

An advanced precooled airbreathing engine with a closed Brayton cycle is a promising solution for high-speed propulsion,of which the Synergetic Air Breathing Rocket Engine(SABRE)is a representative *** performance of the latest SABRE-4 cycle was analyzed in this ***,a relatively complete engine performance model that considers the characteristics of turbomachinery and heat exchangers was ***,Sobol’global sensitivity analysis of key performance parameters was carried out to identify the most influential design *** specific impulses under different target specific thrusts were obtained by particle swarm optimization,of which the thermodynamic parameters corresponding to a specific thrust of 1.12 kN·s·kg^(-1)and a specific impulse of 3163 s were chosen as the design *** different control laws were analyzed in contrast,and the charge control method had the strongest ability of thrust regulation as well as maintaining a favorable specific impulse ***,working characteristics under the charge control and over a typical flight envelope were calculated,in which the average value of the maximum specific impulse was as high as 5315 *** study would help to deepen the understanding of SABRE-4 thermodynamic characteristics and other precooled airbreathing engine cycles with similar layouts.

关键词： Hypersonic Precooled airbreathing engine Thermodynamic cycle Control law Working characteristics

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An efficient chiral synthesis of (R)-N-[3-acetyl-4-(2-hydroxy-3-isopropylamino-propoxy)phenyl]-butanamide with high enantioselectivity

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Science china Chemistry 2009年第8期52卷 1216-1219页

作者： WANG NaiXing1,2 & TANG XinLiang1,3.1.Technical Institute of Physics and Chemistry,Chinese Academy of sciences,beijing 100080,china 2 college of Chemistry and Chemical Engineering,Graduate university of Chinese Academy of sciences,beijing 100049,china 3 School of Chemical Engineering and Environment,beijing Institute of technology,beijing 100081,china Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing China college of Chemistry and Chemical Engineering Graduate University of Chinese Academy of Sciences Beijing China School of Chemical Engineering and Environment Beijing Institute of Technology Beijing China

R-Enantiomer of the β-receptor antagonist N-[3-acetyl-4-(2-hydroxy-3-isopropylamino-propoxy)phenyl] butanamide with high enantioselectivity was synthesized from cheap starting materials and enantiopure chiral reagent through an efficient,convenient and practical synthetic *** product was detected by 1H NMR,13C NMR,and MS,and the enatiomeric excess was determined by chiral HPLC analysis using a chiracel AD-H column.

关键词： chiral synthesis enantioselectivity enatiomeric excess chiral HPLC analysis

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Broadband intelligent programmable metasurface with polarization-modulated self-adaptive electromagnetic functionality switching

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Photonics Research 2024年第7期12卷 1395-1409页

作者： XIMING LI RUI xu XIAOFENG SUN YUAN ZHAO ZHAO YANG GUOHONG du college of Electronic Engineering Chengdu University of Information TechnologyChengdu 610225China

Programmable metasurfaces have received a great deal of attention due to their ability to dynamically manipulate electromagnetic(EM) waves. Despite the rapid growth, most of the existing metasurfaces require manual control to switch among different functionalities, which poses severe limitations on practical applications. Here, we put forth an intelligent metasurface that has self-adaptive EM functionality switching in broadband without human participation. It is equipped with polarization discrimination antennas(PDAs) and feedback components to automatically adjust functionalities for the different incident polarization information.

关键词： equipped adjust polarization

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A New Genetic Algorithm Based on Niche Technique and Local Search Method

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Journal of university of Science and technology beijing 2001年第1期8卷 63-68页

作者： Jinwu xu, Jiwen Liu Mechanical Engineering School, university of Science and technology beijing, beijing 100083, china Mechanical Engineering School Univ. of Sci. and Technology Beijing Beijing 100083 China

The genetic algorithm has been widely used in many fields as an easy robust global search and optimization method. In this paper, a new generic algorithm based on niche technique and local search method is presented under the consideration of inadequacies of the simple genetic algorithm. In order to prove the adaptability and validity of the improved genetic algorithm, optimization problems of multimodal functions with equal peaks, unequal peaks and complicated peak distribution are discussed. The simulation results show that compared to other niching methods, this improved genetic algorithm has obvious potential on many respects, such as convergence speed, solution accuracy, ability of global optimization, etc.

关键词： genetic algorithm (GA) niche technique local search method

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Ballistic target recognition based on multiple data representations and deep-learning algorithms

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Chinese Journal of Aeronautics 2024年第6期37卷 167-181页

作者： Lixun han Cunqian FENG Xiaowei HU Sisan HE xuguang xu Air and Missile Defense college Air Force Engineering UniversityXi’an 710051China college of Information and Communication National University of Defense TechnologyWuhan 430010China

Target recognition is a significant part of a Ballistic Missile Defense System(BMDS).However,most existing ballistic target recognition methods overlook the impact of data representation on recognition *** paper focuses on systematically investigating the influences of three novel data representations in the Range-Doppler(RD)***,the Radar Cross Section(RCS)and micro-Doppler(m-D)characteristics of a cone-shaped ballistic target are ***,three different data representations are proposed:RD data,RD sequence tensor data,and RD trajectory *** accommodate various data inputs,deep-learning models are designed,including a two-Dimensional Residual Dense Network(2D RDN),a three-Dimensional Residual Dense Network-Gated Recurrent Unit(3D RDN-GRU),and a Dynamic Trajectory Recognition Network(DTRN).Finally,an Electromagnetic(EM)computation dataset is collected to verify the performances of the networks.A broad range of experimental results demonstrates the effectiveness of the proposed ***,several key parameters of the proposed networks and datasets are extensively studied in this research.

关键词： Ballistic target Micro-Doppler Deep learning Range-Doppler Radar target recognition

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