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Science China(Technological Sciences) 2004年第3期47卷 293-304页

作者： liu peng jin yaqiu The Key Laboratory of Wave Scattering and Remote Sensing Information Ministry of Education Fudan University Shanghai 200433 China The Key Laboratory of Wave Scattering and Remote Sensing Information Ministry of Education Fudan University Shanghai 200433 China

To study bistatic scattering from a target at low altitude above two- dimensional (2D) randomly rough sea surface under an electromagnetic (EM) wave incidence at low grazing angle (LGA), a numerical approach of the finite element method (FEM) is developed. The conformal perfectly matched layer (PML), as the truncation boundary of the FEM, is employed to reduce the reflection error of planar PML in conventional FEM. Numerical code of our FEM is examined by available solution of the forward backward iterative (FBM) method. Bistatic and back-scattering from composite model of a target above random rough sea surface generated by Monte Carlo realization, and functional dependence upon the sea surface wind speed, target altitude, incident and scattering angles, etc. are numerically simulated and discussed. This paper presents a numerical description of the observation principle and physical insight associated with the coupling interactions of a complex volumetric target and random rough sea surface.

关键词： rough surface, low altitude target, EM scattering, LGA, FEM, PML.

Numerical simulation of the EM scattering and Doppler spectrum of a low flying target above dynamic oceanic surface by using the FEMDDM method

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Science China(Physics,Mechanics & Astronomy) 2004年第5期47卷 597-611页

作者： liu peng jin yaqiu Key Laboratory of Wave Scattering and Remote Sensing Information Ministry of Education Fudan University Shanghai 200433 China Key Laboratory of Wave Scattering and Remote Sensing Information Ministry of Education Fudan University Shanghai 200433 China

To study the Doppler (DP) spectrum of a flying target above the dynamic oceanic surface, a two-level quasi-stationary algorithm (TLQSA) of the finite element method (FEM) with domain decomposition (DDM) is developed. The DP spectrum of a fast-moving target requires a small time-sampling rate. At most time steps, scattering from the flying target is solved by the FEM solution in only one sub-domain; meanwhile the interactions between the target and rough sea surface in other sub-domains are obtained by solving the global DDM coupling matrices. The slowly moving sea surface is evolved at a larger time step and the DP of oceanic clutter is obtained through all-subdomain FEM calculation. Numerical simulations of the DP spectrum from a target flying above the dynamic oceanic surface with and without a ship presence are obtained. The functional dependence of the DP spectrum in both the time and frequency domains upon the sea surface wind speed, target altitude, observation angle etc. are demon- strated and discussed.

关键词： Doppler spectrum, rough surface and target, electromagnetic scattering, domain decomposition method, finite element method.

Highly efficient capture of thorium ion by citric acid-modified chitosan gels from aqueous solution

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Chinese Chemical Letters 2024年第5期35卷 361-365页

作者： Linshan peng Qihang peng Tianxiang jin Zhirong liu Yong Qian State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices East China University of TechnologyNanchang 330013China

A novel citric acid-modified chitosan gel(CSCA)was synthesized through a simple one-step process and was used to extract thorium ions from *** CSCA samples with varying chemical compositions were analyzed using SEM with mapping EDS,FT-IR,and static water contact angle measurements,and their adsorption behaviors were studied in *** results showed that the adsorption performance of CSCA improves with the increase of CA content in the *** possesses an impressive capacity for thorium adsorption of 279.8 mg/***,it showed an ultra-fast adsorption rate and reached equilibrium within 30 *** terms of recyclability,the CSCA still retained more than 86%of its initial adsorption capacity after 6 cycles of *** functional theory(DFT)analysis reveals that the good selectivity of this material towards thorium ions should be attributed to the high density of adsorption sites and strong interaction between carboxyl groups and thorium *** work could be beneficial in the design and synthesis of new polymer materials for extracting thorium.

关键词： Thorium Adsorption Citric acid Chitosan DFT calculation

Interface Design Strategy for GNS/AZ91 Composites with Semi-Coherent Structure

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 467-483页

作者： jing-peng Xiong Yi-Qi Zeng jin-Long liu Wei-Cheng Wang Lan Luo Yong liu Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China School of Physics and Materials Science Nanchang UniversityNanchang 330031China

The interfacial structure plays an important role in the mechanical properties of magnesium matrix composite(MMCs)reinforced with graphene nanosheet(GNS)due to their poor wettability with the Mg *** interface design strategy was proposed to form the semi-coherent interfacial structure with superior bonding *** lattice mismatch and interfacial bonding strength between Mg/rare earth oxide/carbon were utilized as key characteristics to evaluate the interfacial *** oxide(La2O3)was selected as the intermediate candidate due to its low lattice mismatch and high interfacial bonding *** identify the interfacial structure of Mg/La2O3/graphene,first-principles calculations were conducted to calculate the ideal work of separation and electronic structure of the *** demonstrated the presence of strong ionic and covalent interactions at the interface,which theoretically verified the strong interfacial bonding strength among Mg/La2O3/graphene *** experimentally validate the interface strength,MMCs with the interface structure of Mg/La2O3/GNS were *** formation of in-situ La2O3 led to the successful attainment of semi-coherent structures between Mg/La2O3 and La2O3/GNS,resulting in high strength and good ductility of the ***,this work proposes a new approach to interface design in MMCs with an enhancement of mechanical properties.

关键词： Interface design strategy Magnesium matrix composite Graphene nanosheets Semi-coherent interface Mechanical properties

In situ Simulation of Thermal Reality

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Research 2024年第2期2023卷 685-690页

作者： peng jin jinrong liu Fubao Yang Fabio Marchesoni Jian-Hua Jiang Jiping Huang Department of Physics State Key Laboratory of Surface Physicsand Key Laboratory of Micro and Nano Photonic Structures(MOE)Fudan UniversityShanghai 200438China Center for Phononics and Thermal Energy Science Shanghai Key Laboratory of Special Artificial Microstructure Materials and TechnologySchool of Physics Science and EngineeringTongji UniversityShanghai 200092China Department of Physics University of CamerinoCamerino 62032Italy Suzhou Institute for Advanced Research University of Science and Technology of ChinaSuzhou 215123China

Simulated reality encompasses virtual,augmented,and mixed realities梕ach characterized by different degrees of truthfulness in the visual perception:"all false","coexistence of true and false,"and"difficult distinction between true and false,"*** all these technologies,however,the temperature rendering of virtual objects is still an unsolved ***,the lack of thermal tactile functions substantially reduces the quality of the user's real-experience *** address this challenge,we propose theoretically and realize experimentally a technological platform for the in situ simulation of thermal *** this purpose,we design a thermal metadevice consisting of a reconfigurable array of radiating units,capable of generating the thermal image of any virtual object,and thus rendering it in situ together with its thermal *** is a substantial technological advance,which opens up new possibilities for simulated reality and its applications to human activities.

关键词： false rendering signature

Total ionizing dose effect modeling method for CMOS digital-integrated circuit

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Nuclear Science and Techniques 2024年第2期35卷 32-46页

作者： Bo Liang jin-Hui liu Xiao-peng Zhang Gang liu Wen-Dan Tan Xin-Dan Zhang School of Computer Science and Technology Xidian UniversityXi’an 710071China

Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was *** digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional *** of these three parts was separately *** the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using *** the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area ***,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital *** experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose *** confirms the practicality and accuracy of the proposed modeling *** TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.

关键词： CMOS digital-integrated circuit Total ionizing dose IBIS model Behavior-physical hybrid model Physical parameters

Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

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Petroleum Science 2024年第2期21卷 974-986页

作者： Xi-Dao Wu peng Xiao Bei liu Guang-jin Chen Jian-Hua Pang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Ocean Intelligence Technology Center Shenzhen Institute of Guangdong Ocean UniversityShenzhen518120GuangdongChina

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility ***,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely *** this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil ***,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT ***,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary ***,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were *** results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) *** inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was ***_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water ***,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,*** work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

关键词： CO_(2)/H_(2)O emulsion High water cut CO_(2) mobility control Enhanced oil recovery

Characterization and degradation of β-Sn particles in thermal aged Pb-rich solder joint for low-temperature co-fired ceramic(LTCC) applications

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Rare Metals 2024年第10期43卷 5346-5361页

作者： jin-Hong liu Zhe Zhu Qiang-Qiang Nie Jun-Fu liu peng He Shu-Ye Zhang State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Anhui Key Laboratory of Microsystem East China Research Institute of Microelectronics School of Materials Science and Engineering Hefei University of Technology

High-lead solder joints are still playing an indispensable role in military and space ***, in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored. This research first performed aging tests on Sn10Pb90 solder joints, the shear strength at room and elevated temperatures gradually reduced, and the resistance increased. Here, a two-layered Ni–Sn intermetallic compound(IMC) structure was identified using transmission electron microscopy(TEM), which could be attributed to the change of Sn content in the solder. Moreover, the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE) difference between Sn and *** analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally, four degradation mechanisms were *** of the IMC layer would result in increased brittleness and resistivity. For particle coarsening, apart from diminishing the ductility and toughness of the solder joint, it would also accelerate the creeping rate by weakening the phase boundary strength. Regarding voids and cracks induced by phase boundary sliding, wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed. Most importantly, the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands, also known as the spalling and delamination of IMCs. Pb diffusion followed a spiral path, which was mutually influenced by orientation misfit and concentration gradient. A technique to prevent cracking was *** research is expected to provide significant technical references for high-lead solder joints.

关键词： Aging Degradation mechanisms High-lead solder joints Properties TEM characterization

Enhancing blocking temperature using inverse hydrogen bonds for non-radical bridged dimeric Dy(Ⅲ)single-molecule magnets

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Science China Chemistry 2024年第10期67卷 3328-3338页

作者： peng-Bo jin Qian-Cheng Luo Ye-Ye liu Yan-Zhen Zheng Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentMOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterXi’an Key Laboratory of Electronic Devices and Material Chemistry and School of ChemistryXi’an Jiaotong UniversityXi’an 710054China

Single-molecule magnets(SMMs)are a kind of nanosized magnetic materials that are capable of storing massive bytes of *** coupling the spin centers in a proper manner is a usual approach to promote the working temperature(or blocking temperature)for *** delocalized radicals have been widely employed to accomplish this ***,we show a new manner by using weak but multiple B–H^(δ-)···Dy^(3+)inverse hydrogen bonding(IHB)interactions to control the magnetic couplings in a series of dimeric dysprosiacaborane *** approach leads to a record high T_(B)^(100s)of 10 K among non-radical bridged dimeric SMMs,which is mainly ascribed to strong ferromagnetic coupling(4.38 cm^(-1))and the proper alignment of the magnetic principle axes of the adjacent dysprosium(Ⅲ)*** verifying by theoretical calculations,these results demonstrate that IHB interactions can be used to construct strong axial ferromagnetic coupling and enhancing magnetic blocking temperature for SMMs.

关键词： single-molecule magnets carborane dysprosium ferromagnetic coupling inverse hydrogen bond

Spatial patterns and driving forces of urban vegetation greenness in China:A case study comprising 289 cities

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Geography and Sustainability 2024年第3期5卷 370-381页

作者： Yansong jin Fei Wang Quanli Zong Kai jin Chunxia liu peng Qin College of Resources and Environment Qingdao Agricultural UniversityQingdao 266109China College of Soil and Water Conservation Science and Engineering Northwest A&F UniversityYangling 712100China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China

Urban vegetation in China has changed substantially in recent decades due to rapid urbanization and dramatic climate ***,the spatial differentiation of greenness among major cities of China and its evolution process and drivers are still poorly *** study examined the spatial patterns of vegetation greenness across 289 cities in China in 2000,2005,2010,2015,and 2018 by using spatial autocorrelation analysis on the Normalized Difference Vegetation Index(NDVI);then,the influencing factors were analyzed by using the optimal parameters-based geographical detector(OPGD)model and 18 natural and anthropogenic *** findings demonstrated a noticeable rise in the overall greenness of the selected cities during *** cities in northwest China and east China exhibited the rapidest and slowest greening,respectively,among the six sub-regions.A significant positive spatial correlation was detected between the greenness of the 289 cities in different periods,but the correlation strength weakened over *** hot and very hot spots in southern and eastern China gradually shifted to the *** the spatial pattern of urban greenness in China is primarily influenced by wind speed(WS)and precipitation(PRE),the interaction between PRE and gross domestic product(GDP)has the highest explanatory *** explanatory power of most natural factors decreased and,conversely,the influence of anthropogenic factors generally *** findings emphasize the variations in the influence strength of multiple factors on urban greenness pattern,which should be taken into account to understand and adapt to the changing urban ecosystem.

关键词： Vegetation greenness Spatial heterogeneity Influencing factors Geographical detector Urban areas