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Accurate electron affinity of atomic cerium and excited states of its anion

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Chinese Physics B 2020年第7期29卷 275-280页

作者： xiao-xi Fu Ru-Lin Tang yu-zhu Lu Chuan-Gang Ning Department of Physics State Key Laboratory of Low-Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China Collaborative Innovation Center of Quantum Matter Beijing 100084China

Electron affinities(EA)of most lanthanide elements still remain unknown owing to their relatively lower EA values and the fairly complicated electronic *** the present work,we report the high-resolution photoelectron spectra of atomic cerium anion Ce−using the slow electron velocity-map imaging method in combination with a cold ion *** electron affinity of Ce is determined to be 4840.62(21)cm^-1 or 0.600160(26)***,several excited states of Ce(^4H9/2,^4I9/2,^2H9/2,^2G9/2,^2G7/2,^4H13/2,^2F5/2,and ^4I13/2)are observed.

关键词： electron affinity cerium anion slow electron velocity-map imaging cold ion trap

Out-of-Plane Compressive Behavior for UHMWPE/Polyurethane Composites after Hygrothermal Treatment

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Journal of Beijing Institute of Technology 2019年第1期28卷 176-183页

作者： Libao zhu Yongqing Li xi zhu Zixu zhu Department of Naval Architecture Engineering Naval University of Engineering

Quasi-static and high strain rate compressive behaviors and failure mechanisms of hygrothermal treated ultra-high molecular weight polyethylene/polyurethane(UHMWPE/PU)composites have been studied in this ***,the UHMWPE composites were immersed in water at 70℃.The out-ofplane compression test was then performed on the dry/wet state specimens at quasi-static states(0.001-0.01 s^(-1))and high strain rate states(800-2 400 s^(-1)).The split Hopkinson pressure bar(SHPB)was adopted in the dynamic tests and waveform shapers were used to smooth and control the incident *** results show that there are two platforms for the water absorption curve of UHMWPE *** absorption of moisture reduces the quasi-static compressive strength of the material while initially increasing,then decreasing the dynamic compressive *** plasticization,fiber/matrix interface degradation and void expansion are the main factors affecting the irregular change of static/dynamic compressive strength of UHMWPE composites.

关键词： ultra-high molecular weight polyethylene(UHMWPE)composite hygrothermal aging split Hopkinson pressure bar(SHPB) compression

Tough Polyion Complex Hydrogel Films of Natural Polysaccharides

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Chinese Journal of Polymer Science 2017年第10期35卷 1276-1285页

作者： Feng-bo zhu Hai-chao yu Wen-xi Lei Ke-feng Ren Jin Qian 吴子良 Qiang Zheng Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Department of Engineering Mechanics Zhejiang University Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

The developments of tough hydrogels in recent years have greatly expanded the applications of hydrogels as structural materials. However, most of the tough hydrogels are made of synthetic polymers. To develop biopolymer-based tough hydrogels has both fundamental and practical significances. Here we report a series of polysaccharides-based tough hydrogel films prepared by polyion complexation and solvent evaporation of chondroitin sulfate（CS） and protonated chitosan（CHT） solutions with different weight ratios. The obtained CS/CHT gel films with thickness of 40-80 μm and water content of 66 wt%-81 wt% possess excellent mechanical properties, with tensile breaking stress and breaking strain being 0.4-3 MPa and 160%-320%, respectively. We found that in the mixture solutions there are large amounts of excess CHT in terms of charges; after swelling the films in water, the acetic acid, which is used to protonate the amino groups of CHT, diffuses out of the gel matrix, enhancing the intermolecular interactions between CHT molecules and thus improving the mechanical properties of gel films, besides the ionic bonds between CS and CHT. Antimicrobial tests also showed that the gel films with low weight ratio of CS to CHT, corresponding to the case with excess CHT, have evident antimicrobial effect. These CS/CHT gel films with good mechanical properties and antimicrobial effect should extend the applications of hydrogels in biomedical fields.

关键词： responsive polymerization methacrylate acrylamide hydrophilic reversible dissipation AMPS toughness swelling

Spheres of Urban Influence and Factors in Beijing-Tianjin-Hebei Metropolitan Region Based on Viewpoint of Administrative Division Adjustment

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Chinese Geographical Science 2017年第5期27卷 709-721页

作者： zhu Jianhua CHEN xi CHEN Tian School of Geographic Sciences Northeast Normal UniversityChangchun 130024China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Northeast Asian Studies College Jilin UniversityChangchun 130012China

The coordinated development of Beijing, Tianjin and Hebei has been elevated as China's important strategy. And, the priority in considering how to bring the maximum effect of their coordinated development into play is to delineate the spheres of urban influence with regard to the cities in the Beijing-Tianjin-Hebei Metropolitan Region. By building an evaluation index system of urban comprehensive strength, this paper applies the principal component analysis method to determine centrality strength of the cities, and the breakpoint theory and weighted Voronoi diagram to identify the spheres of urban influence in all central cities of the region. Results show that 13 central cities within the region greatly differ in strength, which can be classified into four tiers and that the spheres of urban influence do not have a high goodness of fit with administrative jurisdiction scope. Cities like Beijing, Tianjin, Shijiazhuang and Handan have larger spheres of urban, spheres of urban influence in Tangshan and Qinhuangdao are basically consistent with their administrative jurisdiction scopes, and seven cities including Langfang and Baoding have smaller spheres of urban influence. So according to these cities' comprehensive strength and spheres of influence, the region can be divided into five plates: Beijing, Tianjin, Shijiazhuang, Tangshan and Handan. The major influence factors for inconsistency between spheres of urban influence and spheres of jurisdiction include difference in urban administrative ranking, small number of central cities with weak strength, discrepancy in the number of counties under jurisdiction, unreasonable spheres of jurisdiction and diversity in topographical conditions. In order to solve the imbalance in the spheres of urban influence and those of jurisdiction and better facilitate the coordinated development of the region, it is advised to adjust administrative areas so as to obtain more optimized urban spatial layout and more reasonable urban scale

关键词： spheres of urban influence urban comprehensive strength adjustment of administrative divisions weighted Voronoi diagram Beijing-Tianjin-Hebei Metropolitan Region

1-set-contractive perturbations of accretive operators in Menger PN-spaces

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Applied Mathematics(A Journal of Chinese Universities) 2012年第3期27卷 363-370页

作者： WU Zhao-qi zhu Chuan-xi Department of Mathematics Nanchang UniversityNanchang 330031China

Based on the topological degree for 1-set-contractive fields established in [11], we discuss the 1-set-contractive perturbation and the existence of zero points for nonlinear equations with accretive mappings in Menge... 详细信息

关键词： topological degree 1-set-contractive perturbation accretive mapping.

IMPLEMENTATION OF MIXED METHODS AS FINITE DIFFERENCE METHODS AND APPLICATIONS TO NONISOTHERMAL MULTIPHASE FLOW IN POROUS MEDIA

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Journal of Computational Mathematics 2006年第3期24卷 281-294页

作者： Zhang-xin Chen xi-jun yu Center for Scientific Computation Box 750156 Southern Methodist University Dallas TX 75275-0156 USA Research Center for Science Xi'an Jiaotong University Xi'an 710049 China Center for Advanced Reservoir Modeling and Simulation College Vof Engineering'PekingI University China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.

关键词： Finite difference Implementation Mixed method Error estimates Superconvergence Tensor coefficient Nonisothermal multiphase Multicomponent flow Porousmedia.

Characteristics of Near Surface Winds over Different Underlying Surfaces in China: Implications for Wind Power Development

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Journal of Meteorological Research 2019年第2期33卷 349-362页

作者： xi GONG Rong zhu Lianshou CHEN Nanjing University of Information Science & Technology Chinese Academy of Meteorological Sciences National Climate Center China Meteorological Administration

Accurate wind and turbulence information are essential to wind energy research and utilization, among which wind shear and turbulence intensity/scale have seldom been investigated. In this paper, the observational data from the100-m high wind towers in xilinhot in Inner Mongolia(2009–10; grassland region), Huanghua in Hebei Province(2009–10; coastal flat region), and xingzi County in Jiangxi Province(2010–11; mountain–lake region) are used to study the variations in near surface winds and turbulence characteristics related to the development of local wind energy over different underlying surfaces. The results indicate that(1) the percentage of the observed wind shear exponents exceeding 0.3 for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10%for the mountain–lake region. In other words, if the wind speed at 10 m is 10 ms^(–1), the percentage of the wind speed at 100 m exceeding 20 ms^(–1) for the grassland region is 6%, while the percentage is 13% for the coastal flat region and 10% for the mountain–lake region.(2) In terms of the turbulent intensity in the zonal, meridional, and vertical directions(I_u, I_v, and I_w, respectively), the frequencies of I_v/I_u < 0.8 in the grassland, coastal flat, and mountain–lake regions are 23%–29%, 32%–38%, and 30%–37%, respectively. Additionally, the frequencies of I_w/I_u < 0.5 in the grassland, coastal flat, and mountain–lake regions are 45%–75%, 52%–70%, and 43%–53%, respectively. The frequencies of I_v/I_u < 0.8 and Iw/I_u < 0.5 in each region mean that I_u is large and the air flow is unstable and fluctuating,which will damage the wind turbines. Therefore, these conditions do not meet the wind turbine design requirements,which must be considered separately.(3) At 50-and 70-m heights, the value of the turbulence scale parameter Λ in the grassland region is greater than that in the coastal flat region, and the latter is greater than that in the mountain–lake region. Therefore, under

关键词： wind energy underlying surface wind shear exponent turbulence turbulent intensity

Effects of UV-B radiation on the growth interaction of Ulva pertusa and Alexandrium tamarense

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Journal of Environmental Sciences 2005年第4期17卷 605-610页

作者： CAIHeng-jiang TANGXue-xi ZHANGPei-yu MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China／／DepartmentofEnvironmentalScienceandEngineeringQingdaoUniversityQingdao266071China

Enhanced UV-B(280-320 nm) radiation resulting from ozone depletion is one of global environmental problems. Not only marine organisms but also marine ecosystems can be affected by enhanced UV-B radiation. The effects of UV-B radiation on interaction of macro-algae and micro-algae were investigated using Ulva pertusa Kjellman and Alexandrium tamarense as the materials in this study. The results demonstrated that UV-B radiation could inhibit the growth of Ulva pertusa and Alexandrium tamarense when they were both mono-cultured, and the growth inhibition of algae was more significant with increasing doses of UV-B radiation. Alexandrium tamarense could inhibit the growth of Ulva pertusa in mixed culture, and the growth inhibition was more significant when increasing the initial cell density. However, Ulva pertusa could inhibit the growth of Alexandrium tamarense in early phase and stimulate the growth in latter phase when they were grown in mixed culture. Lower initial cell density(10~2 cell/ml) of Alexandrium tamarense could inhibit the growth of Ulva pertusa under UV-B radiation treatment,however, with the initial cell density increasing(10~3 and 10~4 cell/ml), the growth of Ulva pertusa was stimulated under lower dose of UV-B radiation and inhibited under higher dose of UV-B radiation by Alexandrium tamarense. Compared with that in mixed culture, Ulva pertusa showed more positive inhibition to the growth of Alexandrium tamarense under UV-B radiation treatment.

关键词： UV-B radiation mono-culture mixed culture Ulva pertusa Alexandrium tamarense growth

基于机器学习的农田土壤抗剪强度参数检测方法研究

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农机化研究 2025年第1期47卷 7-15页

作者：于艳艳朱龙图刘鹤吉林农业大学信息技术学院长春130118 云南农业大学机电工程学院昆明650201 农业农村部长江中下游农业装备重点实验室武汉430070

土壤抗剪强度参数包括粘聚力和内摩擦角,是评价土壤侵蚀敏感性和反映耕层耕作性能的重要指标。为实现农田土壤抗剪切强度参数的快速检测,提出了一种基于机器学习的土壤抗剪切强度参数检测方法。以STM32单片机为核心处理器,采用圆锥杆、... 详细信息

土壤抗剪强度参数包括粘聚力和内摩擦角,是评价土壤侵蚀敏感性和反映耕层耕作性能的重要指标。为实现农田土壤抗剪切强度参数的快速检测,提出了一种基于机器学习的土壤抗剪切强度参数检测方法。以STM32单片机为核心处理器,采用圆锥杆、滚珠丝杆滑台、三角支架等构建土壤数据采集装置,利用DYMH-103柱式压力传感器和FlexiForce薄膜传感器分别检测圆锥杆贯入土壤的锥尖阻力和锥侧压力,采用CSF11土壤水分传感器获取土壤含水率信息,通过多传感器数据特征向量提取构建建模数据集。数据集相关性分析结果表明:土壤抗剪强度参数与锥尖阻力、锥侧压力和土壤含水率之间具有明显相关性。利用蒙特卡罗交叉验证(Monte Carlo Cross Validation,MCCV)剔除了数据集中的4个异常样本;同时,提出了一种ELM-PLSR组合建模算法,以决定系数R^(2)和RPD为评价指标,对比评估了ELM、PLSR和ELM-PLSR 3种不同机器学习模型,结果表明:ELM-PLSR模型预测性能优于ELM模型和PLSR模型;检测粘聚力时,对应的R^(2)、RPD分别为0.919和3.475;检测内摩擦角时,对应的R 2和RPD分别为0.910和3.304。研究结果可为土壤抗剪强度参数快速测量提供参考。

关键词：机器学习土壤抗剪强度多传感器特征向量预测模型

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