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Science china Chemistry 2009年第11期52卷 1961-1968页

作者： REN Jie1,2.WANG BingWu1 & CHEN ZhiDa1 1 beijing National Laboratory for Molecular sciences,State Key Laboratory of Rare Earth Materials Chemistry and Applications,{2. of Chemistry and Molecular Engineering,Peking university,beijing 100871,china 2.{2. of Science,Hebei university of Science and technology,Shijiazhuang 050018,china 1. beijing National Laboratory for Molecular sciences State Key Laboratory of Rare Earth Materials Chemistry and Applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China 2. college of Science Hebei University of Science and Technology Shijiazhuang 050018 China

The magnetic coupling interactions of the nitronyl nitroxide radicals bound to diamagnetic(YⅢ) and paramagnetic(GdⅢ) rare earth ions in two model magnetic systems based on novel rare earth organic radical complexes Ln(hfac)3(NITPhOCH3)2.Ln=YⅢ 1,GdⅢ 2.hafc = hexafluoroacetylacetonate;NIT-PhOCH3 = 4'-methoxyo-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been investigated by density functional theory(DFT).The magnetic coupling mechanisms were also explored from the viewpoint of molecular orbital and spin density *** calculations show that the empty 4d-orbitals of YⅢ and 5d-orbitals of GdⅢ play an important role in the antiferromagnetic coupling between the two nitronyl nitroxide radical ligands,and that the ferromagnetic coupling between the GdⅢ ion and the radical magnetic centers can be attributed to the nearly complete localization of the isotropic 4f-shell and singly occupied magnetic orbital(π) of the nitronyl nitroxide.

关键词： magnetic coupling density functional theory rare earth ion gadolinium(Ⅲ) complexes yttrium(Ⅲ) complexes

Approximation bounds for quadratic maximization and max-cut problems with semidefinite programming relaxation

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Science china Mathematics 2007年第11期50卷 1583-1596页

作者： Da-chuan xu~(1+) Shu-zhong ZhanG~2.1 Department of {2. Mathematics,beijing university of technology,{2. 10002.,china 2.Department of Systems Engineering and Engineering Management,The Chinese university of Hong Kong,Shatin,Hong Kong,china 1. Department of applied Mathematics Beijing University of Technology Beijing 100022 China 2. Department of Systems Engineering and Engineering Management The Chinese University of Hong Kong Shatin Hong Kong China

In this paper,we consider a class of quadratic maximization *** a subclass of the problems,we show that the SDP relaxation approach yields an approximation solution with the worst-case performance ratio at leastα=0.87856….In fact,the estimated worst-case performance ratio is dependent on the data of the problem withαbeing a uniform lower *** light of this new bound,we show that the actual worst-case performance ratio of the SDP relaxation approach (with the triangle inequalities added) is at leastα+δ_d if every weight is strictly positive,whereδ_d>0 is a constant depending on the problem dimension and data.

关键词： quadratic maximization max-cut problem semideflnite programming relaxation approximation algorithm performance ratio

Quasi-secure quantum dialogue using single photons

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Science china(Physics,Mechanics & Astronomy) 2007年第5期50卷 558-562页

作者： YANG YuGuang1,2.& WEN QiaoYan31 college of Computer Science and {2., {2., beijing 10002., china 2.State Key Laboratory of Information Security, Graduate university of the Chinese Academy of sciences, beijing 100049, china 3 School of Science, beijing university of Posts and Telecommunications, beijing 100876, china college of Computer Science technology Beijing University of Technology Beijing 100022 China State Key Laboratory of Information Security Graduate University of the Chinese Academy of Sciences Beijing 100049 China School of Science Beijing University of Posts Telecommunications Beijing 100876 China

A quasi-secure quantum dialogue protocol using single photons was proposed. Different from the previous entanglement-based protocols, the present protocol uses batches of single photons which run back and forth between the two parties. A round run for each photon makes the two parties each obtain a classical bit of information. So the efficiency of information transmission can be increased. The present scheme is practical and well within the present-day technology.

关键词： quantum dialogue, single photon, quantum secure direct communication

A fiducial argument for generalized p-value

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Science china Mathematics 2007年第7期50卷 957-966页

作者： Xin-min LI~(1+) Xing-zhong xu~2.Guo-ying LI~3.1.Institute of {2. Mathematics,Shandong {2. of technology,Zibo 2.5049,china 2.Department of Mathematics,beijing Institute of technology,beijing 100801,china 3 Academy of Mathematics and Systems Science,Chinese Academy of sciences,beijing 100800,china Institute of applied Mathematics Shandong University of Technology Zibo 255049 China Department of Mathematics Beijing Institute of Technology Beijing 100801 China Academy of Mathemtics Systems Science Chinese Academy of Sciences Beijing 100800 China

This paper provides a general method for constructing generalized p-value via the fiducial ***,the power properties of the generalized test are *** illustrations, the two-parameter exponential distribution and unbalan... 详细信息

关键词： fiducial distribution generalized p-value frequency property two-parameter exponential distribution variance component 62.03 62.15

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 2.01 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 2..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

Temperature-controlled ionic liquid dispersive liquid phase microextraction combined with ultra-high-pressure liquid chromatography for the rapid determination of triclosan,triclocarban and methyl-triclosan in aqueous samples

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Science china Chemistry 2010年第12期53卷 2600-2607页

作者： GUO JieHong 1,2.LI XingHong 2.CAO xueLi 1,QU Lei 2.3,HOU DeKun 2.& xu XiaoBai 2.1 School of Chemical and Environmental Engineering,beijing technology and Business {2.,beijing 100048,china 2.State Key Laboratory of Environmental Chemistry and Eco-toxicology Research Center of Eco-Environmental sciences,Chinese Academy of sciences,beijing 100085,china 3 Zhengzhou {2.,Zhengzhou 450001,china 1. School of Chemical and Environmental Engineering Beijing Technology and Business University Beijing 100048 China2. State Key Laboratory of Environmental Chemistry and Eco-toxicology Research Center of Eco-Environmental sciences Chinese Academy of Sciences Beijing 100085 China3. Zhengzhou University Zhengzhou 450001 China

As extraction solvents,ionic liquids have green *** this study,an environmentally benign analytical method termed temperature-controlled ionic liquid dispersive liquid phase microextraction (TIL-DLME) combined with ultra-highpressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV) was developed for the pre-concentration and determination of triclosan (TCS),triclocarban (TCC) and methyl-triclosan (M-TCS) in water *** parameters that may affect extraction efficiencies were examined and optimized,including the types and amount of ionic liquids,volume of the diluent,heating temperature,cooling time,salt effect and pH *** the optimum conditions,linearity of the method was observed in the ranges of 0.0100-100 μgL-1 for TCS and M-TCS,and 0.00500-50.0 μgL-1 for TCC with correlation coefficients (r2. > *** limits of detection (LODs) ranged from 1.15 to 5.33 *** in domestic water and TCC in reclaimed water were detected at the concentrations of 1.01 and 0.12. μgL-1,*** spiked recoveries of the three target compounds in reclaimed water,irrigating water,waste water and domestic water samples were obtained in the ranges of 68.4%-71.9%,61.6%-87.8%,58.9%-74.9% and 64.9%-92.4%,*** with the previous dispersive liquid-liquid microextraction method (DLLME) about the determination of TCS,TCC and M-TCS,this method is not only more environmentally friendly but also more sensitive.

关键词： ionic liquid temperature-controlled ionic liquid dispersive liquid phase microextraction UHPLC aqueous samples

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

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Science china Chemistry 2006年第5期49卷 466-474页

作者： NIU Yuwen1,2.HE Lingyan1,2.HU Min2.ZhanG Jing2.& ZHAO Yunliang2.1. Shenzhen Gra{2.ate School of Peking university,Shenzhen 518055,china 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control,{2. of Environmental sciences,Peking university,beijing 100871,china 1. Shenzhen Graduate School of Peking university Shenzhen 518055 China 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing 100871 China

Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2.04. Totally 30 sets of 2. h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. during the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. during the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South china Sea in summer, and the air quality was good. The prevailing wind in winter was from china's Mainland to the north, and the polluted air mass led to poor air quality.

关键词： PM2.5, mass concentration, secondary pollution, seasonal variation, Shenzhen.

A new method of ionospheric-free hybrid differential positioning based on a double-antenna CAPS receiver

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Science china(Physics,Mechanics & Astronomy) 2009年第3期52卷 368-375页

作者： GUO JinYun1,2. han YanBen1 & ChanG XiaoTao{2.National Astronomical Observatories, Chinese Academy of sciences, {2. 100012. china 2.college of Geodesy and Geomatics, Shandong university of Science and technology, Qingdao 2.6510, china 3 Chinese Academy of Surveying and Mapping, {2. 100039, china 1. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. college of Geodesy and Geomatics Shandong University of Science and Technology Qingdao 266510 China 3. Chinese Academy of Surveying and Mapping Beijing 100039 China

Chinese Area Positioning System (CAPS) is a transmitted satellite navigation system moved by the Chinese Academy of sciences. Three basic modes of navigation and positioning with CAPS are given, and then a comparative analysis is made in this paper. In terms of the principle that the ionospheric delay is at an inverse ratio to the frequency square, a new ionospheric-free positioning method based on a double-antenna CAPS receiver is put forward. Then the hybrid differential observations and the solving equations and algorithms for one epoch and multi epochs are deduced according to the basic principle of the method. The method may remove the global errors in signal emission, propagation, transmission and receiving (e.g., ionospheric delay, hardware delay, and clock error). So it is very convenient for the single-epoch solution and multi-epoch navigation and positioning, and may efficiently improve the precision of real time CAPS navigation. Furthermore, the method can be used not only for the geometric orbit determination of CAPS GEO and IGSO satellites and the navigation and positioning, but also for the estimation of the tropospheric zenith delay, which is useful for the study of water vapor c{2.ges in the atmosphere. Polynomials are used in this method to express the tropospheric zenith delay and CAPS satellite orbits within the limited time interval, which reduces the num- ber of unknown parameters and thus speeds the computation.

关键词： Chinese Area Positioning System (CAPS) ionospheric-free linear combination double-antenna receiver hybrid differential positioning method

Analysis of coupling from core mode to counter-propagating radiation modes in tilted fiber Bragg gratings

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Science china(Information sciences) 2010年第5期53卷 1078-1088页

作者： LU ShaoHua 1,2., xu Ou 1,2., FENG SuChun 1,2., DONG XiaoWei 1,2., PEI Li 1,2.& JIAN ShuiSheng 1,2.1 Key Laboratory of All Optical Network & Advanced Telecommunication Network of EMC, {2. Jiaotong university, {2. 100044, china 2.Institute of Lightwave technology, {2. Jiaotong university, {2. 100044, china 1. Key Laboratory of All Optical Network & Advanced Telecommunication Network of EMC Beijing Jiaotong University Beijing 100044 China2. Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China

Radiation-mode coupling is stronger and more efficient in tilted fiber Bragg gratings than in other fiber gratings; it has good advantage in such fields as optical communication and optical sensors. A simplified coupled-mode theory (CMT) approach is proposed for what we believe to be the first time, whose validity is demonstrated by comparing its simulation results with that of the complete CMT equations. With the simplified CMT approach, a theoretical spectral analysis of coupling from core mode to counter-propagating radiation modes in reflective tilted fiber Bragg gratings is presented. The influence of grating length, refractive index modulation amplitude and tilt angle is exhaustively investigated on the transmission spectrum characteristics. The different dependences between s-polarized and p-polarized radiation-mode coupling on grating tilt angle are discussed, and the coupling strength of 45 -tilted gratings shows the greatest polarization dependence with the limitation of backward-propagating radiation-mode coupling.

关键词： fiber optics tilted fiber Bragg gratings coupled-mode theory radiation-mode coupling

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 {2. 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