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Observational evidences of wave excitation and inverse cascade in a distant Earth foreshock region

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Science China Earth Sciences 2019年第4期62卷 619-630页

作者： Jiansen HE Die DUAN Xingyu ZHU limei yan Linghua WANG School of Earth and Space Sciences Peking University Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences

The foreshock with nascent plasma turbulence is regarded as a fascinating region to understand basic plasma physical processes, e.g., wave-particle interactions as well as wave-wave couplings. Although there have been plenty of intensive studies on this topic, some key clues about the physical processes still lack observations. A relatively comprehensive case study with some new observations is presented in this work based on the WIND spacecraft observations. In this case, upstream energetic protons were drifting at tens of Alfvén speed with respect to the background plasma protons. When looking at the magnetic wave activities, we find the co-existence of high-frequency(0.1-0.5 Hz) large-amplitude right-hand polarized(RHP) waves and lowfrequency(0.02-0.1 Hz) small-amplitude left-hand polarized(LHP) waves in the spacecraft(SC) frame. The observed anticorrelation between magnetic and velocity fluctuations along with the sunward magnetic field direction indicates that the lowfrequency LHP waves in the SC frame are in fact the sunward upstream RHP Alfvénic waves in the solar wind frame. This new observation corroborates the applicability of theories about plasma non-resonance instability and inverse cascade to the foreshock region, where the downstream high-frequency RHP parent waves are excited by the upstream energetic protons through non-resonance instability and the low-frequency RHP daughter waves are generated by the parent waves due to nonlinear parametric instability. Furthermore, enhanced downstream energetic proton fluxes are inferred to result from scattering of the upstream protons by the nascent turbulent fluctuations. Therefore, some critical clues about the newborn turbulence in the foreshock are provided in this work.

关键词： Solar wind Foreshock Wave-particle interaction Parametric instability

Effects of natural forest conversion and plantation tree species composition on soil macrofauna communities in Northeast China mountains

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Journal of Forestry Research 2023年第5期34卷 1475-1489页

作者： Shuangjiao Ma Qingcheng Wang Yong Zhang limei yan Donghai Cui Liqing Xu Key Laboratory for Sustainable Forest Ecosystem Management−Ministry of Education School of ForestryNortheast Forestry UniversityHarbin 150040People’s Republic of China

As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil *** determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a *** macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation *** monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary *** Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest *** negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved *** conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community *** impact of forest conversion on soil macrofauna was closely dependent on tree species composition and *** macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.

关键词： Forest conversion Plantation forest Tree species composition Soil macrofauna Diversity Functional group

Plasma draining and replenishing near a solar active region inferred from cross-correlation between radiation intensity and Doppler shift

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Science China Earth Sciences 2015年第5期58卷 830-838页

作者： ZHANG JingBo HE JianSen yan limei TU ChuanYi WANG LingHua WANG Xin Institute of Space Physics and Applied Technology Peking University

Using observations from the EUV Imaging Spectrometer （EIS） onboard Hinode, we exam the plasma dynamics around the edge of the active region 10977, possibly associated with the source of nascent slow/intermediate solar wind. The correlation between the temporal profiles of the radiation intensity and Doppler shift for each emission line are analyzed. And three small regions with positive correlations for all the five emission lines are selected for a detailed analysis. In this work, Doppler blue （red） shift is defined as negative （positive）. We find that in Region 1, the radiation intensity （Doppler velocity） decreases by about 15% （about 3 km s-X）, and logarithmical differential emission measures （lg（DEMs）） reduces by about 0.06-0.10% at all temperatures, called ＂weak dimming＂, during a 30-min interval. In Region 2 and Region 3, however, the radiation intensity （Doppler velocity） increases by about 15% （about 3 km s-l）, and lg（DEMs） increases by about 0.06%~0.10% at all tempera- tures, called ＂weak brightening＂. Such weak dimming （weak brightening） could reflect a slow draining （replenishing） of plas- ma in the solar wind flux tubes, possibly due to a larger （smaller） outflow flux at high altitude than at low altitude. These sug- gest that the plasma supply could be intermittent with an alternation of draining and replenishing, for which the underlying physical process is yet unknown, at the source region of slow/intermediate solar wind.

关键词： solar corona solar wind active region

Prediction of solar activities:Sunspot numbers and solar magnetic synoptic maps

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Science China Earth Sciences 2024年第8期67卷 2460-2477页

作者： Rui ZHUO Jiansen HE Die DUAN Rong LIN Ziqi WU limei yan Yong WEI School of Earth and Space Sciences Peking UniversityBeijing 100091China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Centre for Mathematical Plasma Astrophysics Department of MathematicsKU LeuvenLeuven 3001Belgium Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The evolution of solar magnetic fields is significant for understanding and predicting solar *** our knowledge of solar magnetic fields largely depends on the photospheric magnetic *** this paper,based on the spherical harmonic expansion of the photospheric magnetic field observed by Wilcox Solar Observatory,we analyze the time series of spherical harmonic coefficients and predict Sunspot Number as well as synoptic maps for Solar Cycle *** find that solar maximum years have complex short-period disturbances,and the time series of coefficient g_(7)~0 is nearly in-phase with Sunspot Number,which may be related to solar meridional *** Long Short-Term Memory networks(LSTM),our prediction suggests that the maximum of Solar Cycle 25 is likely to occur in June 2024 with an error of 8 months,the peak sunspot number may be 166.9±22.6,and the next solar minimum may occur around January *** incorporating Empirical Mode Decomposition,we enhance our forecast of synoptic maps truncated to Order 5,validating their relative *** prediction not only addresses a gap in forecasting the global distribution of the solar magnetic field but also holds potential reference value for forthcoming solar observation plans.

关键词： Solar activity prediction Solar magnetic field Spherical harmonic expansion Long-Short Term Memory(LSTM) Empirical Mode Decomposition(EMD)

Expected value model for portfolio selection based on risk curve in birandom environments

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Expected value model for portfolio selection based on risk c...

Development of High Efficient and Low Toxic Oil Spill Dispersants based on Sorbitol Derivants Nonionic Surfactants and Glycolipid Biosurfactants

第三届中国智能计算大会

作者： limei yan Department of Mathematics Dezhou University,Dezhou,253023,China

＜正＞In order to solve the portfolio problem when security returns are birandom variables,firstly we propose a definition of risk on the basis of the average chance of birandom variable,then one type of portfolio selection based on expected value and risk is provided according to birandom ***,A hybrid intelligent algorithm integrating birandom simulation and genetic algorithm is ***,one numerical experiment is provided to illustrate the effectiveness of the hybrid intelligent algorithm.

关键词： birandom variable portfolio selection expected value operator confidence curve hybrid intelligent algorithm

来源： cnki会议评论

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Journal of Environmental Protection 2013年第1期4卷 16-22页

作者： Dandan Song Shengkang Liang Qianqian Zhang Jiangtao Wang limei yan Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education Qingdao 266100 China College of Chemistry and Chemical Engineering Ocean University of China Qingdao 266100 China

Dispersants, usually blending with several surfactants and a solvent, are used to enhance oil spill dispersion as small droplets in water column. Although there is growing acceptance of dispersants as a counter measure to marine oil spills around the world, the two major issues with the dispersants are their toxicity to marine life and dispersion effectiveness (DE) for crude-oil, especially for heavy oil. To develop more efficient and less toxic dispersants, two kinds of sorbitol derivant nonionic surfactant (polysorbate 85 and sorbeth-40 tetraoleate), two kinds of glycolipid biosurfactants (rhamnolipid and sophorolipid) and less toxic solvent ethylene glycol butyl ether were chosen in this study, and two dispersant formulations were optimized by uniform design methods. Effects of dispersant-to-oil ratio, temperature, salinity and pH on the performance of the two optimized dispersants were investigated. The two dispersants had high dispersion effectiveness (DE) for heavy crude oil, while both dispersants keep high DE at the dispersant-to-oil ratio below 1:25 and the temperature above 5 ℃. In addition, the two dispersants also performed well in a wide range of salinity and pH values. Finally, toxicity tests revealed that the two dispersants showed low toxicity to two kinds of fish (Danio rerio and Microgobius gulosus).

关键词： Oil spill dispersant Formula uniform design Baffled Flask Test Effectiveness Toxicity

The solar wind plasma upstream of Mars observed by Tianwen-1:Comparison with Mars Express and MAVEN

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Science China Earth Sciences 2022年第4期65卷 759-768页

作者： Kai FAN limei yan Yong WEI Aibing ZHANG Linggao KONG Markus FRÄNZ Fei HE Lihui CHAI Chongjing YUAN Yuqi WANG Jun ZHONG Zhaojin RONG Zhonghua YAO Yongxin PAN Jun CUI Jiansen HE Wenya LI Binbin TANG Chi WANG Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China National Space Science Center Chinese Academy of SciencesBeijing 100190China Beijing Key Laboratory of Space Environment Exploration Beijing 100190China Key Laboratory of Science and Technology on Space Environment Situational Awareness Chinese Academy of SciencesBeijing 100190China Max-Planck-Institute for Solar System Research Goettingen 37077Germany State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai 519082China Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China

On the great journey to Mars,China’s first planetary exploration mission,the Tianwen-1 came within 26 million kilometers of Mars from 31 October 2020 to 25 January 2021 and was getting closer to its destination,the red planet,in search of answers to the cataclysmic climate change that occurred in Martian *** the escape of the Martian atmosphere and the loss of surface water were firmly influenced by solar ***-1 provided a unique chance to depict the solar wind streams between Earth and Mars during the minimum of Solar Cycle *** the three-month cruise phase of Tianwen-1,the solar wind flows were successively observed at Earth,Tianwen-1,and *** the field of view correction and noise reduction,the solar wind velocity and density measured by Tianwen-1 show good agreement with those at Earth and *** results indicate that the performance of the ion analyzer onboard the Tianwen-1 orbiter is reliable and *** is worth looking forward to the joint observations of ion escape with other Mars probes in the following Martian years.

关键词： Tianwen-1 Mars Plasma moment Solar wind

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双随机变量证券投资组合决策

计算机工程与应用 2012年第12期48卷 209-212,228页

作者：闫立梅德州学院数学系山东德州253023

将收益率刻画为双随机变量,建立了均值-方差证券投资组合模型;研究并给出了双随机变量期望值和方差的一般计算方法,将模型转化为其确定等价形式;讨论了模型的凸性,证明了模型解的存在性和惟一性;通过数值例子验证了模型和方法的可行性。

关键词：双随机变量投资组合模型双随机变量的方差确定等价类

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模糊层次分析法在变压器脆性分析中的应用

电工技术学报 2005年第2期20卷 94-98页

作者：徐建军闫丽梅刘小斌大庆石油学院电气工程系大庆163318

采用模糊层次分析法对系统脆性进行了分析。由模糊层次分析法得到了因素(或元件)的相对重要度排序矢量,通过定义脆性激发度及激发阈值,对系统的脆性是否被激发进行了理论的分析。通过分析,可以找出系统中的脆性元件或因素,可以最大程度... 详细信息

采用模糊层次分析法对系统脆性进行了分析。由模糊层次分析法得到了因素(或元件)的相对重要度排序矢量,通过定义脆性激发度及激发阈值,对系统的脆性是否被激发进行了理论的分析。通过分析,可以找出系统中的脆性元件或因素,可以最大程度地避免脆性的发生。最后以变压器故障的模糊层次分析为例,从变压器故障因素的相对重要度入手,找出了容易引起变压器故障的脆性因素,经检验该方法是可行的,同时说明进行系统的脆性分析是完全必要的。

关键词：模糊层次分析法系统的脆性脆性激发度激发阈值相对重要度