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Comparison of Constituents and Insecticidal Activities of Essential Oil from Artemisia lavandulaefolia by Steam Distillation and Supercritical-CO_2 Fluid Extraction

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Chemical Research in Chinese Universities 2010年第6期26卷 888-892页

作者： YUAN Hai-bin shang li-na WEI Chun-yan REN Bing-zhong Jilin Key Laboratory of Animal Resource Conservation and Utilization School of Life Sciences Northeast Normal University Changchun 130024 P. R. China College of Agronomy Jilin Agricultural University Changehun 130118 P. R. China Jilin Entry-Exit Inspection and Quarantine Bureau Changchun 130062 P. R. China

Essential oil was extracted from Artemisia lavandulaefolia *** steam distillation（SD） and supercritical-CO2 fluid extraction（SFE）,*** constituents of the essentil oils extracted with those two methods were analyzed by gas chromatography-mass spectrometry（GC-MS） and insecticidal activities of the essential oils were evaluated,then the results were compared to assess their biological ***-one compounds were identified in the essential oil extracted by SD,and its main components were eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol and so ***-two compounds were identified for the essential oil extracted by SFE,and its main components were cyclodecene,n-hexadecanoic acid and so *** chemical compositions were all contained in the essential oils extracted by the two methods,i.e.,eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol,caryophyllene,[3aS-（3aα,3bβ,4β,7α,7aS）]-octahydro-7-methyl-3-methylene-4-（1-methylethyl）-1H-cyclopenta[1,3]cyclopropa-[1,2]benzene,nerolidol and（-）-*** fumigation toxicity of the essential oil obtained by means of SD to the adults of Sitophilus zeamais is significantly higher than that of the essential oil by means of *** contact toxicity of the essential oil obtained by means of SFE to the adults of *** is higher than that of the essential oil obtained by means of SD,but the difference is not significant.

关键词： Artemisia lavandulaefolia DC. Essential oil Supercritical-CO2 fluid extraction Steam distillation GC-MS Insecticidal activity

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Impact of the Political Risk on Food Reserve Ratio:Evidence Across Countries

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Journal of Systems Science & Complexity 2024年第5期37卷 2071-2103页

作者： XING Kai li shang YANG Xiaoguang School of Economics&Management Nanchang University Department of Statistics and Data Science National University of Singapore Academy of Mathematics and Systems Science Chinese Academy of Sciences University of Chinese Academy of Sciences

Using an unbalanced panel data covering 75 countries from 1991 to 2019, the authors explore how the political risk impacts on food reserve ratio. The empirical findings show that an increasing political risk negatively affects food reserve ratio, and the same effects hold for both internal risk and external risk. Moreover, the authors find that the increasing external or internal risks both negatively affect food production and food exports, but external risk does not significantly impact food imports and it positively impacts food consumption, while internal risk negatively impacts food imports and food consumption. The results suggest that most governments have difficulty raising subsequent food reserve ratios in face of an increasing political risk, no matter if it is an internal risk or an external risk although the mechanisms behind the impacts are different.

关键词： External risk food reserve ratio internal risk political risk

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Dynamic modeling and RBF neural network compensation control for space flexible manipulator with an underactuated hand

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Chinese Journal of Aeronautics 2024年第3期37卷 417-439页

作者： Dongyang shang Xiaopeng li Meng YIN Fanjie li School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China

In space operation,flexible manipulators and gripper mechanisms have been widely used because of light weight and ***,the vibration caused by slender structures in manipulators and the parameter perturbation caused by the uncertainty derived from grasping mass variation cannot be *** existence of vibration and parameter perturbation makes the rotation control of flexible manipulators difficult,which seriously affects the operation accuracy of ***’s more,the complex dynamic coupling brings great challenges to the dynamics modeling and vibration *** solve this problem,this paper takes the space flexible manipulator with an underactuated hand(SFMUH)as the research *** dynamics model considering flexibility,multiple nonlinear elements and disturbance torque is established by the assumed modal method(AMM)and Hamilton’s principle.A dynamic modeling simplification method is proposed by analyzing the nonlinear ***’s more,a sliding mode control(SMC)method combined with the radial basis function(RBF)neural network compensation is ***,the control law is designed using a saturation function in the control method to weaken the chatter *** the help of neural networks to identify the uncertainty composition in the SFMUH,the tracking accuracy is *** results of ground control experiments verify the advantages of the control method for vibration suppression of the SFMUH.

关键词： Space flexible manipulator RBF neural network Underactuated hand Dynamic models Model simplification

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The Adjustment Analysis Method of the Active Surface Antenna Based on Convolutional Neural Network

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Research in Astronomy and Astrophysics 2024年第6期24卷 294-306页

作者： You Ban shang Shi na Wang Qian Xu Shufei Feng School of Mechanical Engineering Xinjiang UniversityUrumqi 830017China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China School of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China

Active surface technique is one of the key technologies to ensure the reflector accuracy of the millimeter/submillimeter wave large reflector *** antenna is complex,large-scale,and high-precision equipment,and its active surfaces are affected by various factors that are difficult to comprehensively deal *** this paper,based on the advantage of the deep learning method that can be improved through data learning,we propose the active adjustment value analysis method of large reflector antenna based on deep *** method constructs a neural network model for antenna active adjustment analysis in view of the fact that a large reflector antenna consists of multiple panels spliced *** on the constraint that a single actuator has to support multiple panels(usually 4),an autonomously learned neural network emphasis layer module is designed to enhance the adaptability of the active adjustment neural network *** classical 8-meter antenna is used as a case study,the actuators have a mean adjustment error of 0.00252 mm,and the corresponding antenna surface error is0.00523 *** active adjustment result shows the effectiveness of the method in this paper.

关键词： techniques:radar astronomy telescopes methods:analytical methods:numerical

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复合材料梁的几何精确非线性建模及非经典效应

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复合材料学报 2018年第1期35卷 218-228页

作者：尚丽娜夏品奇南京航空航天大学航空宇航学院南京210016

基于Hodges的广义Timoshenko梁理论对具有任意剖面形状、任意材料分布及大变形的复合材料梁进行几何精确非线性建模,采用旋转张量分解法计算梁内任意一点的应变,采用变分渐近法确定梁剖面的任意翘曲,采用平衡方程由二次渐近精确的应变... 详细信息

基于Hodges的广义Timoshenko梁理论对具有任意剖面形状、任意材料分布及大变形的复合材料梁进行几何精确非线性建模,采用旋转张量分解法计算梁内任意一点的应变,采用变分渐近法确定梁剖面的任意翘曲,采用平衡方程由二次渐近精确的应变能导出广义Timoshenko应变能,采用广义Hamilton原理建立梁的几何精确非线性运动方程。将所建模型用于复合材料梁的静动力分析,通过与实验数据的对比,验证了建模方法的准确性,并进一步研究了剖面翘曲及横向剪切变形非经典效应对复合材料梁的影响。研究表明,剖面翘曲对复合材料梁的静变形和固有频率有显著影响,横向剪切变形对复合材料梁的静变形和固有频率的影响与梁的长度/剖面高度比有关。

关键词：复合材料梁几何精确非经典效应翘曲横向剪切变形

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Recent progress in visualization and digitization of coherent transformation structures and application in high-strength steel

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1298-1310页

作者： Xuelin Wang Zhenjia Xie Xiucheng li Chengjia shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Yangjiang Branch Guangdong Laboratory for Materials Science and Technology(Yangjiang Advanced Alloys Laboratory)Yangjiang 529500China

High-strength steels are mainly composed of medium-or low-temperature microstructures,such as bainite or martensite,with coherent transformation *** type of microstructure has a high density of dislocations and fine crystallographic structural units,which ease the coordinated matching of high strength,toughness,and ***,given its excellent welding perform-ance,high-strength steel has been widely used in major engineering constructions,such as pipelines,ships,and ***,visual-ization and digitization of the effective units of these coherent transformation structures using traditional methods(optical microscopy and scanning electron microscopy)is difficult due to their complex ***,the establishment of quantitative relationships with macroscopic mechanical properties and key process parameters presents additional *** article reviews the latest progress in microstructural visualization and digitization of high-strength steel,with a focus on the application of crystallographic methods in the development of high-strength steel plates and *** obtained the crystallographic data(Euler angle)of the transformed microstruc-tures through electron back-scattering diffraction and combined them with the calculation of inverse transformation from bainite or martensite to austenite to determine the reconstruction of high-temperature parent austenite and orientation relationship(OR)during con-tinuous cooling ***,visualization of crystallographic packets,blocks,and variants based on actual OR and digit-ization of various grain boundaries can be effectively completed to establish quantitative relationships with alloy composition and key process parameters,thereby providing reverse design guidance for the development of high-strength steel.

关键词： high-strength steel microstructure visualization digitization quantification mechanical properties

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Revealing effect of Al content on oxidation of novel Co-Cr-Nb-W carbide-strengthened superalloy

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Rare Metals 2024年第9期43卷 4521-4534页

作者： Chen ling shang-Ping li Jie Hou He-li Luo Central Iron & Steel Research Institute Beijing GAOna Materials&Technology Co. Ltd.

The high-temperature oxidation behavior of novel Co-Cr-Nb-W carbide-strengthened wear-resistance alloys with different Al contents（1wt%, 2wt% and 3wt%）at 950, 1000 and 1050 °C was thoroughly investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and field emission electron probe analyzer. The porous property of Nb C in-situ oxidation products（Nb2O5, Co Nb2O6and Co4Nb2O9） induces a multi-layered oxide scale with micropores and ***-Cr-Nb-W alloy with 1 wt% Al undergoes catastrophic oxidation and spalling above 1000 °C. The outward transportation of Cr and Co is effectively restrained by a continuous Al2O3scale formed around Nb C in-situ oxidation region when Al content reaches 3 wt%. The β-Co Al in Co-Cr-Nb-W alloy with 3 wt% Al has an oxidation priority over eutectic carbides and the alloy matrix which are both enriched with Cr, thereby preventing the formation of Cr-depletion area and improving the self-healing ability of the oxide film. A slight change in Al content has a remarkable influence on the cooperative effect of Al and Cr and multiplies the antioxidant capacity of Co-Cr-Nb-W alloy above 1000 °C.

关键词： High-temperature oxidation behavior Microstructure Oxidation kinetics Superalloy Wear-resistant alloy

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Pre-reduction of WO_(3)-Co_(3)O_(4)by H_(2)-C_(2)H_4 in a fluidized bed

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Chinese Journal of Chemical Engineering 2024年第2期66卷 273-284页

作者： Huijun shang Hengli li Weijun li Feng Pan Zhan Du State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences(CAS)Beijing 100190China College of Chemical Engineering Nanjing Technology UniversityNanjing 211816China School of Chemistry and Chemical Engineering Shihezi UniversityShihezi 832003China College of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Chinalco Environmental Protection and Energy Conservation Group Co. Ltd.Xiong’an 071700China

In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been *** study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon *** results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are *** pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)

关键词： Fluidization WO_(3)-Co_(3)O_(4) Reduction Carbon deposition Rate equation

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Approximations to Isentropic Planar Magneto-Hydrodynamics Equations by Relaxed Euler-Type Systems

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Chinese Annals of Mathematics,Series B 2024年第3期45卷 413-440页

作者： Yachun li Zhaoyang shang Chenmu WANG liang ZHAO School of Mathematical Sciences CMA-ShanghaiMOE-LSC and SHL-MACShanghai Jiao Tong UniversityShanghai 200240China School of Finance Shanghai Lixin University of Accounting and FinanceShanghai 201209China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences Harbin Engineering UniversityHarbin 150001China Mathematical Modelling&Data Analytics Center Oxford Suzhou Centre for Advanced ResearchSuzhou 215123JiangsuChina

In this paper, the authors consider an approximation to the isentropic planar Magneto-hydrodynamics(MHD for short) equations by a kind of relaxed Euler-type system. The approximation is based on the generalization of the Maxwell law for nonNewtonian fluids together with the Maxwell correction for the Ampe`re law, hence the approximate system becomes a first-order quasilinear symmetrizable hyperbolic systems with partial dissipation. They establish the global-in-time smooth solutions to the approximate Euler-type equations in a small neighbourhood of constant equilibrium states and obtain the global-in-time convergence towards the isentropic planar MHD equations. In addition, they also establish the global-in-time error estimates of the limit based on stream function techniques and energy estimates for error variables.

关键词： Planar MHD equations Relaxation limits Global convergence Stream function

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Debris Flow Susceptibility Evaluation in Meizoseismal Region:A Case Study in Jiuzhaigou,China

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Journal of Earth Science 2024年第1期35卷 263-279页

作者： Yongwei li linrong Xu Yonghui shang Shuyang Chen School of Civil Engineering Central South UniversityChangsha 410075China national Engineering Research Center of High-Speed Railway Construction Technology Central South UniversityChangsha 410075China School of Civil Engineering Central South University of Forestry and TechnologyChangsha 410004China

Jiuzhaigou is situated on a mountain-canyon region and is famous for frequent tectonic *** abundance of loose co-seismic landslides and collapses were produced on gullies after the Jiuzhaigou Earthquake on August 8,2017,which was served as material source for debris flow in later *** flow appears frequently which are seriously endangering the safety of people's lives and *** the earliest debris flow appeared in areas where no case ever reported *** debris flow susceptibility evaluation(DFSE)is used for predicting the areas prone to debris flow,which is urgently required to avoid hazards and help to guide the strategy of preventive ***,this work employs debris flow in Jiuzhaigou to reveal the characteristics of disaster-pregnant environment and to explore the application of machine learning in *** new viewpoints are suggested:(i)Material density factor of debris flow is first adopted in this work,and it is proved to be a critical factor for triggering debris flows by sensitivity analysis method.(ii)Deep neural network and convolutional neural network(CNN)achieve relatively good area under the curve(AUC)values and are 0.021-0.024 higher than traditional machine learning methods.(iii)Watershed units combined with CNNbased model can achieve more accurate,reliable and practical susceptibility *** work provides an idea for prevention of debris flow in mountainous lands.

关键词： machine learning earthquakes debris flow susceptibility convolutional neural network deep neural network watershed unit

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