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Litterfall production and nutrient return in different-aged Chinese fir(Cunninghamia lanceolata) plantations in South China

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Journal of Forestry Research 2015年第1期26卷 79-89页

作者： Lili zhou Addo-Danso Daniel Shalom Pengfei Wu Shubin Li yayun Jia Xiangqing Ma Forestry College Fujian Agriculture and Forestry University Chinese fir Engineering Technology Research Center of the State Forestry Administration Faculty of Forestry University of British Columbia Ecosystem Services and Climate Change Division CSIR-Forestry Research Institute of Ghana

The amounts of litter produced and nutrients returned play a fundamental role in the productivity and biogeochemical and nutrient cycling of forest *** monitored annual litterfall production, nutrient return,and monthly dynamics over a one-year period in Chinese fir plantations aged 10, 22, and 34 years. Our objective was to quantify litterfall and nutrient return over a complete harvest rotation of Chinese fir. Annual litterfall production increased with stand age and was recorded as（3,294.6 ± 360.4）,（3,733.9 ± 211.2）, and（4,876.1 ± 212.8） kg ha-1a-1in stands aged 10, 22 and 34 years, respectively. Total litter production was significantly greater in the stand aged34 years than in the stand aged 10 years（p ／ 0.05）. With the exception of miscellaneous components, needle litterfall constituted the highest proportion（27.5–43.6 %）, followed by branches/twigs（9.5–16.6 %）. In all three plantations,annual total nutrient return to soil was in the order of C（1,119.95–2,709.05 kg ha-1a-1） [ N（39.32–62.04 kg ha-1a-1） [ K（15.95–22.44 kg ha-1a-1） [ P（1.30–1.63 kg ha-1a-1）. C, N, K and P input to soil was significantly lower in the 10-year-old stand in comparison to the 22- and34-year-old stands（p ／ 0.05）. Litterfall production and nutrient return（C, N and K） followed similar patterns, and C and N input to soil was significantly related to litterfall production（needle, branch and total litterfall）. C, N, P and K input to soil and total litterfall production were mainly driven by needle litterfall.

关键词： Cunninghamia lanceolata Litterfall production Nutrient return

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A LINEARLY-IMPLICIT ENERGY-PRESERVING ALGORITHM FOR THE TWO-DIMENSIONAL SPACE-FRACTIONAL NONLINEAR SCHRÖDINGER EQUATION BASED ON THE SAV APPROACH

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Journal of Computational Mathematics 2023年第5期41卷 797-816页

作者： yayun Fu Wenjun Cai Yushun Wang School of Science Xuchang UniversityXuchang 461000China Jiangsu Key Laboratory for NSLSCS Jiangsu Collaborative Innovation Center of Biomedial Functional MaterialsSchool of Mathematical SciencesNanjing Normal UniversityNanjing 210023China

The main objective of this paper is to present an efficient structure-preserving scheme,which is based on the idea of the scalar auxiliary variable approach,for solving the twodimensional space-fractional nonlinear Schrodinger ***,we reformulate the equation as an canonical Hamiltonian system,and obtain a new equivalent system via introducing a scalar ***,we construct a semi-discrete energy-preserving scheme by using the Fourier pseudo-spectral method to discretize the equivalent system in space *** that,applying the Crank-Nicolson method on the temporal direction gives a linearly-implicit scheme in the fully-discrete *** expected,the proposed scheme can preserve the energy exactly and more efficient in the sense that only decoupled equations with constant coefficients need to be solved at each time ***,numerical experiments are provided to demonstrate the efficiency and conservation of the scheme.

关键词： Fractional nonlinear Schrodinger equation Hamiltonian system Scalar auxiliary variable approach Structure-preserving algorithm

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High strength and high ductility Mg-Gd-Y-Zn-Zr alloys obtained by controlling texture and dynamic precipitation through LPSO phase structure of different initial morphologies

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Journal of Rare Earths 2024年第12期42卷 2217-2230页

作者： yayun He Rui Guo Xi Zhao Zhimin Zhang College of Mechanical and Electrical Engineering North University of China School of Aeronautics and Astronautics North University of China College of Materials Science and Engineering North University of China

This paper investigated the effects of three different initial phase structures on the microstructure evolution and tensile properties of extruded Mg-Gd-Y-Zn-Zr alloy, using an extrusion ratio of 3.6. These three initial phase structures were obtained by heat treatment, which is narrow spacing long-period stacking ordered phase(LPSO) phase structure alloy(EN alloy), wide spacing LPSO phase structure alloy(EW alloy), and narrow spacing LPSO phase and β phase overlapping phase structure alloy(EO alloy). The dynamic recrystallization(DRX) and dynamic precipitation behavior of extruded alloys with different initial structures, as well as their strengthening and ductility mechanisms were studied in detail. After hot extrusion with a low extrusion ratio, the alloy exhibits a bimodal structure composed of undynamic recrystallization(UN-DRX) grains and dynamic recrystallization(DRX) grains with strong textures. The narrow-spacing LPSO phase structure inhibits DRX and dynamic precipitation, while both the wide-spacing LPSO phase structure and the overlapping phase structure alloys promote DRX and dynamic precipitation. The strength improvement is mainly due to the strong texture and internal dislocation pinning of the undynamic recrystallization zone(UN-DRX) and the high strengthening effect of the narrow spacing LPSO phase. Although the promotion of DRX improves grain boundary strengthening effect, it cannot make up for reducing the UN-DRXed grain strengthening effect. A lower volume fraction of β dynamic precipitation phase is beneficial for improving the ductility of the alloy.

关键词： Mechanical property Mg-Gd-Y-Zn-Zr alloy Rare earths Recrystallization behavior

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Advances in the development and component recognition of latent fingerprints

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Science China Chemistry 2015年第7期58卷 1090-1096页

作者： Linru Xu Congzhe Zhang yayun He Bin Su Institute of Microanalytical Systems Department of ChemistryZhejiang University State Key Laboratory of Natural Medicines China Pharmaceutical University

Fingerprints have been used as an indispensable tool for personal identification in forensic investigations since the late 19 th century. At present, fingerprinting technology has moved away from its forensic roots and is incorporating a broader scientific range, e.g., material science, spectroscopy and spectral analysis, and even in vitro diagnosis. After a brief introduction to latent fingerprints, this mini-review presents the pioneering progresses of fingerprinting technologies including(i) material and electrochemical techniques, and(ii) spectral and spectroscopy imaging techniques and immunological techniques capable of both the visualization of a fingerprint and the detection of chemicals present in it. Finally, perspectives on this rapidly developing field are discussed.

关键词： latent fingerprints recognition immunoassay aptamer mass spectrometry

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鸡公山5种森林水样的水质分析

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南方林业科学 2021年第6期49卷 16-20页

作者：李月凤柳勇张宏伟周亚运马冠男张建设河南省信阳市林业科学研究所河南信阳464031 河南鸡公山森林生态系统国家定位观测研究站河南信阳464031

在森林区域内,大气降水、穿透雨、树干径流、地表径流和集水区径流5种类型水样的表现性状可以大致模拟大气降水对森林垂直层面的作用与影响。本文通过对2020年3月-10月期间鸡公山森林区域内的上述5种类型水样的pH值等水质指标进行定位... 详细信息

在森林区域内,大气降水、穿透雨、树干径流、地表径流和集水区径流5种类型水样的表现性状可以大致模拟大气降水对森林垂直层面的作用与影响。本文通过对2020年3月-10月期间鸡公山森林区域内的上述5种类型水样的pH值等水质指标进行定位观测和对比,得到了该区域内穿透雨、树干径流和地表径流的大部分指标浓度值高于大气降水从而呈现正向效应,集水区径流的大部分指标浓度低于大气降水则呈反向效应的结论。并通过对实验结果的分析,阐释了大气降水透过森林林冠层、林下枯落物层的元素变化规律,为深入研究森林水文的内在运行机制提供依据。

关键词：森林大气降水水质

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Implementation of Balanced Strength and Toughness of VW93A Rare-Earth Magnesium Alloy with Regulating the Overlapping Structure of Lamellar LPSO Phase and β′Phase

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Acta Metallurgica Sinica(English Letters) 2024年第10期37卷 1735-1751页

作者： Chao Wang Xi Zhao yayun He Dingxia Zheng School of Aerospace Engineering North University of ChinaTaiyuan030051China School of Mechanical and Electrical Engineering North University of ChinaTaiyuan030051China

Although extensive research has been conducted on the strengthening mechanism of rare-earth magnesium alloys,achieving a balance between strength and toughness has proven *** paper introduces a method for regulating the overlapping structure of the lamellar long-period stacking ordered(LPSO)phase andβ′phase to achieve a balance between strength and toughness in the *** focusing on the extruded VW93A alloy cabin component,the study delves into the mechanism of the alloy's strength and toughness through a comparative analysis of the microstructure characteristics and room-temperature mechanical properties of the alloys in various ***,the molecular dynamics simulation is employed to clarify the mechanism of the alloy's strength and toughness balance induced by the overlapping *** findings reveal that when theβ′phase precipitates in the alloy alone,a significant increase in strength is achieved by pinning dislocations,albeit at the expense of reduced ***,the presence of the lamellar LPSO phase disperses dislocations between the LPSO phase lamellae,thereby enhancing plasticity by avoiding stress concentration resulting from dislocation *** both phases coexist in the alloy and form an overlapping structure,the dispersion of dislocations due to the lamellar LPSO phase weakens the pinning effect of theβ′phase,further reducing dislocation stacking and resulting in a balance of strength and toughness in the ***,the alloy with the overlapping structure exhibits an ultimate tensile strength and elongation of 421 MPa and 20.1%,respectively.

关键词： Extrusion Rare-earth magnesium alloys Cabin component Long-period stacking ordered(LPSO)phase β'phase Molecular dynamics simulations

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Graphitic carbon nitride-based photocatalysts in the applications of environmental catalysis

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Journal of Environmental Sciences 2023年第2期124卷 570-590页

作者： Hongxia Lin JinmoWu Fan zhou Xiaolong Zhao Pengfei Lu Guanghui Sun Yuhan Song yayun Li Xiaoyong Liu Hongxing Dai Hefei Institute for Public Safety Research Tsinghua UniversityHefei 230601China Anhui Province Key Laboratory of Human Safety Hefei 230601China Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaLaboratory of Catalysis Chemistry and NanoscienceDepartment of Environmental Chemical EngineeringSchool of Environmental and Chemical EngineeringFaculty of Environment and Life ScienceBeijing University of TechnologyBeijing 100124China

Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution *** key issue is the development of high-efficiency *** strategies in the state-of-the-art advancements,such as heterostructure construction,heteroatom doping,metal/single atom loading,and defect engineering,have been presented for the graphitic carbon nitride(g-C3N4)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic *** this review,nanoarchitecture design,synthesis methods,photochemical properties,potential photocatalytic applications,and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly *** superior photocatalytic performance was identified to be associated with the enhanced visible-light response,fast photoinduced electron-hole separation,efficient charge migration,and increased unsaturated active ***,the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.

关键词： Graphitic carbon nitride-based photocatalyst Photocatalytic reduction Photocatalytic degradation Chemical modification Heterostructure construction Metal doping

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豫南引种不同薄壳山核桃无性系果(核)与产量的数量性状研究

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河南科学 2023年第2期41卷 183-191页

作者：章理运申明海王晓云邱林余开慧周宁宁李凤英吴文竹周亚运河南省信阳市林业科学研究所河南信阳464031

为探明豫南地区引种不同薄壳山核桃无性系间果(核)与产量数量性状的差异及遗传稳定性,进而对无性系进行评价,以16个薄壳山核桃无性系为试验对象,对其果(核)与产量的12个数量性状进行观测研究,分析性状的差异、变异系数、重复力,并对重... 详细信息

为探明豫南地区引种不同薄壳山核桃无性系间果(核)与产量数量性状的差异及遗传稳定性,进而对无性系进行评价,以16个薄壳山核桃无性系为试验对象,对其果(核)与产量的12个数量性状进行观测研究,分析性状的差异、变异系数、重复力,并对重要性状进行主成分分析.结果表明,不同薄壳山核桃无性系各性状指标之间的差异显著.坚果质量性状上,‘波尼’、132号、C21号、11号、13号、35号、64号等7个无性系坚果种仁较为饱满,质量较优;28号、104号、C10号、1号等4个无性系半饱或空瘪率较多.?果和核果的产量变异最大,变异系数平均值达49.37%和49.32%,单果质量、单核质量、青皮厚度变异系数的平均值分别为26.26%、20.48%、25.80%,?果长、宽,核果长、宽变异系数的平均值分别为9.37%、9.46%和7.36%、6.89%,变异较小.11个数量性状的重复力均在70%以上,其中,?果纵径的重复力最高(0.997),表明各无性系继承原株优良性状的比率较高.主成分分析表明,?果、核果的大小、质量和单株产量是影响薄壳山核桃综合性状的重要指标,其次是出核率、出仁率和坚果饱满率,反映了薄壳山核桃无性系数量性状的大部分信息,得出‘波尼’、35号、13号、64号等无性系的坚果综合性状较优.

关键词：薄壳山核桃数量性状变异系数重复力主成分分析豫南地区

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Study on Spray Characteristics of Dimethyl Carbonate Blended Fuel in IC Engines

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China Petroleum Processing & Petrochemical Technology 2021年第4期23卷 29-36页

作者： Fu Wei zhou Kun Liu Junya Xie Hongxi Li yayun Lu Lei Bao Jihu Cheng Yunlang Hefei General Machinery Research Institute Hefei 230031

The spray characteristics of the blended fuel composed of biodiesel and dimethyl carbonate were compared with those of biodiesel and *** macroscopic spray characteristic parameters including spray tip penetration,maximum spray width,average spray cone angle,and peak tip velocity were used to evaluate the spray characteristics of the blended *** results showed that the spray tip penetration of blended fuel was lower than that of biodiesel,while the spray cone angle and maximum spray width of blended fuel were both larger than that of *** the basis of the Hiroyasu and Arai mathematical model combined with the actual working conditions of this experiment,including physical parameters such as the viscosity and density of the fuel,a correct model of spray penetration was established,and the experimental results were compared.

关键词： biodiesel dimethyl carbonate diesel spray characteristics mathematical model

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Numerical analysis and optimization of boundary layer suction on airfoils

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Chinese Journal of Aeronautics 2015年第2期28卷 357-367页

作者： Shi yayun Bai Junqiang Hua Jun Yang Tihao School of Aerodynamics Northwestern Polytechnical University Chinese Aeronautical Establishment

Numerical approach of hybrid laminar flow control （HLFC） is investigated for the suc- tion hole with a width between 0.5 mm and 7 mm. The accuracy of Menter and Langtry＇s transition model applied for simulating the flow with boundary layer suction is validated. The experiment data are compared with the computational results. The solutions show that this transition model can pre- dict the transition position with suction control accurately. A well designed laminar airfoil is selected in the present research. For suction control with a single hole, the physical mechanism of suction control, including the impact of suction coefficient and the width and position of the suc- tion hole on control results, is analyzed. The single hole simulation results indicate that it is favor- able for transition delay and drag reduction to increase the suction coefficient and set the hole position closer to the trailing edge properly. The modified radial basis function （RBF） neural net- work and the modified differential evolution algorithm are used to optimize the design for suction control with three holes. The design variables are suction coefficient, hole width, hole position and hole spacing. The optimization target is to obtain the minimum drag coefficient. After optimization, the transition delay can be up to 17% and the aerodynamic drag coefficient can decrease by 12.1%.

关键词： Active control Hybrid laminar flow control(HLFC) Neural network Optimization Radial basis function (RBF)Transition prediction

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