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Animal Husbandry and Feed Science 2017年第2期9卷 112-114页

作者： Ma Donglai Shen zhengxian Du Huiru Zhang Zhidong Jiang Cuilan Wang Liang Li Jing zheng yuguang College of Pharmacy Hebei University of Chinese MedicineShijiazhuang 050200China Hebei Development Center of Traditional Chinese Medicine Shiji-azhuang 050051China Hebei Chemical&Pharmaceutical College Shijiazhuang 050026China

With sulphur-fumigated Chinese medicinal materials （Fritillaria thunbergii , Isatis #utigotica , Asparagus cochinchinensis and Poria cocos ） as the test materials, sulfur dioxide or sulfite residue was determined by the method in Chinese Pharmacopoeia （2015 edition） and titration-fluorescence spectrometry, respec- tively. The results showed that there were significant differences in measured value between titration-fluorescence spectrometry and phmmacopoeia method. The t result of titration-fluorescence spectrometry was much closer to the actual content of sulfur dioxide in Chinese medicinal materials. Thus, titration-fluo- rescence spectrometry had higher application value

关键词： Titration-fluorescence spectrometry Chinese Pharmacopoeia Sulfur dioxide Chinese medicinal materials Residue

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特高压换流变压器阀侧出线绝缘结构电场分析

高电压技术 2022年第9期48卷 3526-3532页

作者：郑劲孔巾娇梁红胜郑宇光冯怡雪文闿成国网特高压公司北京100052 国网湖北电力有限公司电力科学研究院武汉430077 国网电力科学研究院武汉南瑞有限公司武汉430074 国网经济技术研究院北京102209

阀侧出线绝缘结构是决定换流变压器安全性的关键部位,包括套管油端、均压电极和多层纸板围屏系统,以及至阀绕组引线的绝缘。该出线结构承受着严酷的交直流电场应力,历来换流变压器在试验中和运行中的绝缘故障很多都发生在这里。为此基... 详细信息

阀侧出线绝缘结构是决定换流变压器安全性的关键部位,包括套管油端、均压电极和多层纸板围屏系统,以及至阀绕组引线的绝缘。该出线结构承受着严酷的交直流电场应力,历来换流变压器在试验中和运行中的绝缘故障很多都发生在这里。为此基于以往设计和试验、特别是对试验中故障的调查分析,聚焦于均压电极区域,综合、归纳了阀侧出线装置的3种典型绝缘结构,即单环电极“半罩”结构、单环电极“全罩”结构、双环电极无绝缘罩结构,提出了一种新的绝缘结构,即“Ω”型绝缘罩结构。用有限元方法建立模型进行交流和直流电场计算和安全性评价。指出了各种结构的风险点,并从理论上指出了改善电场分布和提高安全性能的方向。计算结果和故障案例一致表明,半绝缘罩的端部油中有很高的沿端面直流电场,可引发局放进而引起沿大绝缘筒闪络;全绝缘罩端部油中直流场强很高,沿引下线头部绝缘表面的电位梯度也很高,可引起引下线头部油中沿面闪络或纸绝缘击穿;双环电极无绝缘罩绝缘电极两侧至大绝缘筒的斜向第一油隙很大,易发生交流放电;“Ω”型绝缘罩可能是兼顾交流和直流绝缘的优化解决方案。

关键词：换流变压器出线绝缘电场强度绝缘成型罩安全评价

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第3代小麦气吸机排种器综合调速系统的研究

农机化研究 2010年第8期32卷 61-64页

作者：郑宇光张晋国河北农业大学机电工程学院河北保定071001

河北农业大学粮食丰产科技工程课题组正在研制第3代小麦缝隙气吸式精播机,其设计特点是机电气液一体化,排种器的转动实现自动综合调速在3代机设计中的应用是突出特色之一。为此,重点阐述了自动综合调速系统的研究。

关键词：小麦气吸式排种器综合调速系统

Plate tectonics in the Archean:Observations versus interpretations

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Science China Earth Sciences 2024年第1期67卷 1-30页

作者： YongFei zheng School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Key Laboratory of Crust-Mantle Materials and Environment Chinese Academy of SciencesHefei 230026China Center of Excellence for Comparative Planetology Chinese Academy of SciencesHefei 230026China

Plate tectonics theory,established in the 1960s,has been successful in explaining many geological phenomena,processes and events that occurred in the ***,the theory has often struggled to provide a coherent framework in interpreting geological records in continental interior and Precambrian *** dealing with the relationship between plate tectonics and continental geology,continental interior tectonics was often separated from continental margin tectonics in the inheritance and development of their structure and *** separation led to the illusion that the plate tectonics theory is not applicable to Precambrian geology,particularly in explaining the fundamental geological characteristics of Archean *** this illusion does not mean that the Archean continental crust did not originate from a regime of plate tectonics,it led to the development of alternative tectonic models,often involving vertical movements under a regime of stagnant lid tectonics,including not only endogenous processes such as gravitational sagduction,mantle plumes and heat pipes but also exogenous processes such as bolide *** vertical processes were not unique to the Archean but persisted into the *** result from mantle poloidal convection at different depths,not specific to any particular *** the plate tectonics theory from the traditional kinematic model in the 20th century to a holistic kinematic-dynamic model in the 21st century and systematically examining the vertical transport of matter and energy at plate margins,it is evident that plate tectonics can explain the common geological characteristics of Archean cratons,such as lithological associations,structural patterns and metamorphic *** deciphering the structure and composition of convergent plate margins as well as their dynamics,the formation and evolution of continental crust since the Archean can be divided into ancient plate tectonics in the Preca

关键词： Plate tectonics Archean geology Continental origin Crustal reworking Plate interior Plate margin

Safe Motion Planning and Control Framework for Automated Vehicles with Zonotopic TRMPC

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Engineering 2024年第2期33卷 146-159页

作者： Hao zheng Yinong Li Ling zheng Ehsan Hashemi State Key Laboratory of Mechanical Transmissions College of Mechanical and Vehicle EngineeringChongqing UniversityChongqing 400044China Department of Mechanical Engineering University of AlbertaEdmontonAB T6G 2H5Canada

Model mismatches can cause multi-dimensional uncertainties for the receding horizon control strategies of automated vehicles(AVs).The uncertainties may lead to potentially hazardous behaviors when the AV tracks ideal trajectories that are individually optimized by the AV's planning *** address this issue,this study proposes a safe motion planning and control(SMPAC)framework for *** the control layer,a dynamic model including multi-dimensional uncertainties is established.A zonotopic tube-based robust model predictive control scheme is proposed to constrain the uncertain system in a bounded minimum robust positive invariant set.A flexible tube with varying cross-sections is constructed to reduce the controller *** the planning layer,a concept of safety sets,representing the geometric boundaries of the ego vehicle and obstacles under uncertainties,is *** safety sets provide the basis for the subsequent evaluation and ranking of the generated *** efficient collision avoidance algorithm decides the desired trajectory through the intersection detection of the safety sets between the ego vehicle and obstacles.A numerical simulation and hardware-in-the-loop experiment validate the effectiveness and real-time performance of the *** result of two driving scenarios indicates that the SMPAC can guarantee the safety of automated driving under multi-dimensional uncertainties.

关键词： Automated vehicles Automated driving Motion planning Motion control Tube MPC Zonotope

Discovery of the Significant Impacts of Swell Propagation on Global Wave Climate Change

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Journal of Ocean University of China 2024年第3期23卷 594-604页

作者： zheng Chongwei Dalian Naval Academy Dalian 116018China Marine Resources and Environment Research Group on the Maritime Silk Road Dalian 116018China

This study compared the differences in the wave climate in the South China Sea and North Indian Ocean under these two datasets:ERA-40 wave reanalysis and Mei’s hindcast wave *** the numerical calculation of regional ocean waves,the wave climate characteristics exhibited significant bias if the influence of external swells(swells from afar)was not fully considered,which may provide an incorrect basis for global climate change analysis.1)The trends of the significant wave height(SWH)obtained from the two datasets showed significant differences,such as those of the Bay of Bengal and the Java Sea in *** the past 45 years,SWH from ERA-40(SWH-ERA)exhibited a significant annual increase in low-latitude waters of the North Indian Ocean(0.2-0.6 cm yr^(-1))and South China Sea(0.2-0.8 cm yr^(-1)).2)In the Bay of Bengal,the SWH-ERA in each month was generally 0.5 m higher than the SWH from Mei’s hindcast wave data(SWH-Mei)and can reach 1.0 m higher in some months.3)In the Bay of Bengal,SWH-ERA and SWH-Mei increased significantly at annual rates of 0.13 and 0.27 cm yr^(-1),*** increasing trend was mainly reflected after ***-ERA showed a trough in 1975(1.33 m)and a crest in 1992(1.83 m),which were not reflected in SWH-Mei.

关键词： wave climate climatic trend monthly variation annual variation external swell

A positive trend in the stability of global offshore wind energy

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Acta Oceanologica Sinica 2024年第1期43卷 123-134页

作者： Chongwei zheng Dalian Naval Academy Dalian 116018China Marine Resources and Environment Research Group on the Maritime Silk Road Dalian 116018China Shandong Provincial Key Laboratory of Ocean Engineering Ocean University of ChinaQingdao 266100China

The recognition on the trend of wind energy stability is still extremely rare,although it is closely related to acquisition efficiency,grid connection,equipment lifetime,and costs of wind energy *** the 40-year(1979–2018)ERA-Interim data from the European Center for Medium-Range Weather Forecasts,this study presented the spatial-temporal distribution and climatic trend of the stability of global offshore wind energy as well as the abrupt phenomenon of wind energy stability in key regions over the past 40 years with the climatic analysis method and Mann-Kendall(M-K)*** results show the following 5 points.(1)According to the coefficient of variation(C_(v))of the wind power density,there are six permanent stable zones of global offshore wind energy:the southeast and northeast trade wind zones in the Indian,Pacific and Atlantic oceans,the Southern Hemisphere westerly,and a semi-permanent stable zone(North Indian Ocean).(2)There are six lowvalue zones for both seasonal variability index(S_(v))and monthly variability index(M_(v))globally,with a similar spatial distribution as that of the six permanent stable zones.M_(v) and S_(v) in the Arabian Sea are the highest in the world.(3)After C_(v),M_(v) and S_(v) are comprehensively considered,the six permanent stable zones have an obvious advantage in the stability of wind energy over other sea areas,with C_(v) below 0.8,M_(v) within 1.0,and S_(v) within 0.7 all the year round.(4)The global stability of offshore wind energy shows a positive climatic trend for the past four decades.C_(v),M_(v) and S_(v) have not changed significantly or decreased in most of the global ocean during 1979 *** is,wind energy is flat or more stable,while the monthly and seasonal variabilities tend to shrink/smooth,which is beneficial for wind energy utilization.(5)C_(v) in the low-latitude Pacific and M_(v) and S_(v) in both the North Indian Ocean and the low-latitude Pacific have an obvious abrupt phenomenon at the end of

关键词： global oceans wind energy stability spatial-temporal distribution climatic trend

Wind power and sand/dust storms

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 175-176页

作者： XiaoJing zheng Center for Particle-Laden Turbulence Lanzhou UniversityLanzhou 730000China

Sand/dust storms,a globally prevalent catastrophic weather phenomenon,can cause significant erosion to the climate and ecological *** high concentration of sand particles they carry not only impacts atmospheric qualit... 详细信息

关键词： Wind power and sand/dust storms

Damping Characteristic Analysis and Optimization of Wind-thermal-bundled Power Transmission by LCC-HVDC Systems

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 299-312页

作者： Liwen zheng Shiying Ma the Power System Department China Electric Power Research InstituteBeijing 100192China

With the rapid development of renewable energy,wind-thermal-bundled power transmission by line-commutated converter based high-voltage direct current(LCC-HVDC)systems has been widely *** dynamic interaction mechanisms among permanent magnet synchronous generators(PMSGs),synchronous generators(SGs),and LCC-HVDC system become *** deal with this issue,a path analysis method(PAM)is proposed to study the dynamic interaction mechanism,and the damping reconstruction is used to analyze the damping characteristic of the ***,based on the modular modeling,linearized models for the PMSG subsystem,the LCC-HVDC subsystem,and the SG subsystem are ***,based on the closed-loop transfer function diagram of the system,the disturbance transfer path and coupling relationship among subsystems are analyzed by the PAM,and the damping characteristic analysis of the SG-dominated oscillation mode is studied based on the damping *** with the PAM,the small-signal model of the system is obtained and eigenvalue analysis results are ***,the effect of the control parameters on the damping characteristic is analyzed and the conclusions are verified by time-domain ***,the penalty functions of the oscillation modes and decay modes are taken as the objective function,and an optimization strategy based on the Monte Carlo method is proposed to solve the parameter optimization *** simulation results are presented to validate the effectiveness of the proposed strategy.

关键词： Wind-thermal-bundled power transmission line-commutated converter based high-voltage direct current(LCC-HVDC) path analysis method(PAM) damping characteristic analysis Monte Carlo method

A Minimum Residual Based Gradient Iterative Method for a Class of Matrix Equations

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 17-34页

作者： Qing-qing zheng Department of Mathematics College of ScienceChina University of Petroleum-BeijingBeijing102249China

In this paper, we present a minimum residual based gradient iterative method for solving a class of matrix equations including Sylvester matrix equations and general coupled matrix equations. The iterative method uses a negative gradient as steepest direction and seeks for an optimal step size to minimize the residual norm of next iterate. It is shown that the iterative sequence converges unconditionally to the exact solution for any initial guess and that the norm of the residual matrix and error matrix decrease monotonically. Numerical tests are presented to show the efficiency of the proposed method and confirm the theoretical results.

关键词： Sylvester matrix equation coupled matrix equation minimum residual gradient descent convergence analysis