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Changes in permafrost and snow cover in the Boreal and Arctic zones(BAZs)and their impacts

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Advances in Climate Change Research 2023年第2期14卷 157-163页

作者： Hui-Jun JIN daqing yang Olga MAKARIEVA Liang TANG School of Civil Engineering|Permafrost Institute Northeast Forestry UniversityHarbin 150040China State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Scientific Observation and Research Station of Permafrost and Cold-Regions Environment in the Da Xing'anling Mountains Northeast ChinaNatural Resources Institute of Heilongjiang ProvinceHarbin 150036China Institute of Tibet Plateau Research Chinese Academy of SciencesBeijing 1000101China National Hydrology Research Centre Environment CanadaSaskatoonSaskatchewan S7N 3H5Canada Institute of Earth Sciences St.Petersburg State UniversitySt.Petersburg199034Russia School of Civil Engineering Harbin Institute of TechnologyHarbin 150090China

*** Amplified climate warming and wetting have been observed in the Boreal and Arctic zones(BAZs).Due to extensive and persistent warming of the climate and the increasing impacts of human activities,we are seeing degradation of the permafrost and rapid shrinkage of the snow cover in the *** attention has been paid to the reconstruction of past permafrost and monitoring,mapping and evaluation of permafrost and snow cover,and the use of models to predict and evaluate future gradual permafrost *** attention,however,has been given to the rapidly changing permafrost and the associated *** may have led to an underestimation of the rapid changes in the cryolithozone and their effects on the climate,ecosystems,and hydrology systems and on *** particular,natural resources and environmental management in northern countries requires better and more systematic understanding of the history,processes,mechanisms and trends of the northern cryosphere and their environmental and engineering impacts.

关键词： Arctic warming ozone

基于小规模限制性在线课程和虚拟仿真实验的免疫学检验混合实验教学模式的思考与探索

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中国医药导报 2024年第1期21卷 77-80页

作者：李秀平林梅阳大庆邹朝霞肖品陈湘莲湖南医药学院公共卫生与检验医学院湖南怀化418000

随着网络技术的发展,面对面课堂讲授教学与在线资源相融合的教学模式将逐渐成为高校教学改革的主要形式。湖南医药学院公共卫生与检验医学院以“免疫学检验”实验课程为例,采用小规模限制性在线课程(SPOC)实验教学融合虚拟仿真实验教学... 详细信息

随着网络技术的发展,面对面课堂讲授教学与在线资源相融合的教学模式将逐渐成为高校教学改革的主要形式。湖南医药学院公共卫生与检验医学院以“免疫学检验”实验课程为例,采用小规模限制性在线课程(SPOC)实验教学融合虚拟仿真实验教学模式构建线上线下混合实验教学模式,以优化教学目标,革新课程教学资源,改革教学方法,优化实验课程考核评价体系,完善教学监管机制为设计思路,并根据实验项目特点采用不同的方式。该教学模式充分调动了学生学习的主动性与创造性,提高了学生时间利用率和学习效率,消除了实验教学盲点,夯实了学生专业技能。该文对小规模限制性在线课程和虚拟仿真实验相结合的线上线下混合实验教学模式进行了探讨和思考,为后续提高实验教学质量,转变实验课程模式奠定了基础。

关键词：免疫学检验小规模限制性在线课程虚拟仿真混合实验教学

Permafrost dynamics and their hydrologic impacts over the Russian Arctic drainage basin

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Advances in Climate Change Research 2021年第4期12卷 482-498页

作者： WANG Kang ZHANG Tingjun daqing yang School of Geographic Sciences East China Normal UniversityShanghai200241China MOE Key Laboratory of Western China's Environmental Systems College of Earth and Environmental SciencesLanzhou UniversityLanzhou730000China University Cooperation for Polar Research(UCPR) Beijing100875China Watershed Hydrology and Ecology Division Environment and Climate Change CanadaVictoriaBC V8W 3R4Canada

Permafrost is an important component in hydrological processes because changes in runoff over the Arctic drainage basin cannot be well explained by changes in precipitation-related ***,current understanding of the influences of permafrost on hydrological dy-namics is *** study investigated historical variations in permafrost conditions and their potential hydrologic effects over the Russian Arctic drainage *** results show that soil temperature(at 0.40 m below surface)has increased about 1.4℃over the Ob,1.5℃over the Yenisei,and 1.8℃over the Lena River basin from 1936 through 2013,possibly resulted in a significant thawing of *** active layer changes have occurred since the *** volume of the active layer increased by 28,142,and 228 km3 over the Ob,Yenisei,and Lena basins,respectively,since the *** ground ice caused by deepening active layer may be a limited contribution to annual *** during freeze season(October--April)showed significant positive correlations(p0.05)in the Ob *** results imply that,in basins with high permafrost coverage,a deeper active layer increased soil water storage capacity and perhaps contribute to an increase in winter runoff.

关键词： Permafrost Active layer Hydrologic response Arctic Russia

Triad-displaced ULAs configuration for non-circular sources with larger continuous virtual aperture and enhanced degrees of freedom

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Journal of Systems Engineering and Electronics 2024年第1期35卷 81-93页

作者： SHAIKH Abdul Hayee DANG Xiaoyu HUANG daqing College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation ***,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for *** TdisULAs structure generally consists of three ULAs,which are appropriately *** proposed antenna array approach fully exploits the non-circular characteristics of the *** the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array ***,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form ***,the proposed array also produces a filled resulting *** simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.

关键词： direction-of-arrival(DOA)estimation sparse array non-circular source(NCS) sum co-array difference co-array degrees of freedom(DOF)

Linkage between permafrost distribution and river runoff changes across the Arctic and the Tibetan Plateau

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Science China Earth Sciences 2020年第2期63卷 292-302页

作者： Chunlin SONG Genxu WANG Tianxu MAO Junchen DAI daqing yang Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China College of Forestry Guizhou UniversityGuiyang 550025China National Hydrology Research Centre Environment CanadaSaskatoon SK S7N 3H5Canada

River runoff in the Arctic and the Tibetan Plateau(TP) change significantly in recent decades. However, the mechanisms of the physical processes of permafrost river runoff change remain uncertain across large scale. This study investigated the mainstreams and tributaries of main Arctic and TP rivers dominated by permafrost and assessed the linkage between hydrological regime change and permafrost. The results show that the effects of permafrost on river runoff are highly dependent on the permafrost coverage of a watershed. For the past decades, the majority of the Arctic and TP basins showed increased discharge, while all of the studied basins showed increased baseflow, with faster increasing speed than total *** total discharge and baseflow annual change rate(ΔQ and ΔBF) increased with permafrost coverage, indicating the increments of streamflow are enhanced with high permafrost coverage. Meanwhile, the annual change of precipitation showed weak connection with total discharge and baseflow change. The high permafrost coverage basins showed high annual maximum/minimum discharge ratio(Qmax/Qmin), while the Qmax/Qminchanged slightly in low permafrost cover basins. Our results highlight the importance of permafrost coverage on streamflow regime change for permafrost basins across the northern hemisphere. Due to these linkage between permafrost extent and runoff regime change and the increasing changes of permafrost, more attention should be paid to the change of hydrological processes in permafrost-underlain basins.

关键词： Permafrost hydrology Arctic rivers Tibetan Plateau rivers Permafrost degradation Runoff change

A compact bimorph rotary piezoelectric actuator with customized small power supply

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Science China(Technological Sciences) 2024年第4期67卷 1185-1195页

作者： DENG Jie LIU daqing WANG WeiYi LIU YingXiang School of Mechatronics and Engineering Harbin Institute of TechnologyHarbin 150001China

Inertial piezoelectric actuators are widely applied in precision devices with simple structure and accurate ***,existing inertial piezoelectric actuators still face the challenges of rollback motion and bulky power *** this work,an alternate excitation strategy and a customized small power supply for a bimorph rotary piezoelectric actuator(BRPA)are proposed to solve the *** BRPA prototype is designed with a bipedal symmetrical structure,measuring 35 mm in height and 32 mm in diameter,which has a maximum rotation velocity of 0.247 rad/s and a resolution of 0.66μ*** to the bipedal symmetrical structure,the friction directions between the driving feet and the rotor can be coordinated to suppress the *** rollback ratio is almost zero when the phase difference of the exciting signal is set as 180°.The customized power supply is designed and manufactured,whose size is 58 mm×56 mm×46 *** can output signals for the single step mode and the continuous mode,and they are adopted to excite BRPA to achieve a small stroke with one single step and a large stroke with continuous step,***,an experimental system for optical fiber alignment is developed based on the BRPA and the customized small power supply,the experiment has verified the practicability of this work in the precision fields,especially in the miniaturized precision systems.

关键词： inertial piezoelectric actuator customized small power supply single step mode continuous mode rollback suppression miniaturized precision system

Microstructures,corrosion behavior and mechanical properties of as-cast Mg-6Zn-2X(Fe/Cu/Ni)alloys for plugging tool applications

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 697-711页

作者： Baosheng Liu Jiali Wei Shaohua Zhang Yuezhong Zhang Pengpeng Wu daqing Fang Guorui Ma School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Intelligent Equipment Research and Development Center Zhuhai Institute of Advanced Technology Chinese Academy of SciencesZhuhai 519080China Advanced Materials Research Institute Zhuhai Dingmei Medical Technology Co.Ltd.Zhuhai 519000China

Mg-6Zn-2X(Fe/Cu/Ni)alloys were prepared through semi-continuous casting,with the aim of identifying a degradable magnesium(Mg)alloy suitable for use in fracturing balls.A comparative analysis was conducted to assess the impacts of adding Cu and Ni,which result in finer grains and the formation of galvanic corrosion *** electronic microscopy examination revealed that precipitated phases concentrated at grain boundaries,forming a semi-continuous network structure that facilitated corrosion penetration in Mg-6Zn-2Cu and Mg-6Zn-2Ni *** corrosion was observed in Mg-6Zn-2Fe,while galvanic corrosion was identified as the primary mechanism in Mg-6Zn-2Cu and Mg-6Zn-2Ni *** the tests,the Mg-6Zn-2Ni alloy exhibited the highest corrosion rate(approximately 932.9 mm/a)due to its significant potential *** testing showed that Mg-6Zn-2Ni alloy possessed suitable ultimate compressive strength,making it a potential candidate material for degradable fracturing balls,effectively addressing the challenges of balancing strength and degradation rate in fracturing applications.

关键词： magnesium alloys microstructure micro-galvanic corrosion mechanical properties

Novel control strategy for the energy recovery system of a hydraulic excavator

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International Journal of Agricultural and Biological Engineering 2024年第2期17卷 94-101页

作者： Changsheng Liu Qinghua He Qijun Tang Kai Ren Jun Gong daqing Zhang The National Enterprise Research and Development Center Sunward Intelligence Equipment Co.Ltd.Changsha 410131China College of Mechanical and Electrical Engineering Hunan Agricultural UniversityChangsha 410128China College of Eletronical and Information Engineering Hunan UniversityChangsha 410082China

The energy saving of hydraulic excavators is always an essential *** energy recovery system can effectively recover the boom potential energy and rotational kinetic *** on the standard working cycle of hydraulic excavators,a dynamic programming(DP)control strategy for hybrid hydraulic excavators was proposed to recover the boom potential energy and rotational kinetic *** hybrid hydraulic excavator simulation model was built by Simulink *** simulation results indicated that the fuel consumption of hybrid hydraulic excavators using the DP control strategy was about 21.3%lower than that of the conventional hydraulic *** order to experimentally verify the simulation results,an experimental platform for hybrid hydraulic excavators was *** experimental results indicated that the fuel consumption of hybrid hydraulic excavators using the DP control strategy was about 18.9%lower than that of the conventional hydraulic *** paper shows that the DP control strategy applied to hybrid hydraulic excavators can recycle the boom potential energy and rotational kinetic energy,and reduce the fuel consumption of hybrid hydraulic excavators.

关键词： hybrid excavator energy recovery control strategy simulation analysis test platform

Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

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原子能科学技术 2024年第4期58卷 705-713页

作者： HOU Lingxiao YUAN Youjin SHEN Guodong RUAN Shuang LIU Jie ZHU Yunpeng WANG Geng GUO Hongliang LYU Mingbang GAO daqing XU Zhiguo SHENG Lina yang Jiancheng Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle ***,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic ***,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal *** the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation *** order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam ***,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation *** mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at *** the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS *** this paper,the method and experimental results were introduced.

关键词： heavy ion accelerator beam uniformity scanning magnet MIC