Magnetopause properties at the dusk magnetospheric flank from global magnetohydrodynamic simulations,the kinetic Vlasov equilibrium,and in situ observations--Potential implications for SMILE

We derived the properties of the terrestrial magnetopause(MP)from two modeling approaches,one global–fluid,the other local–kinetic,and compared the results with data collected in situ by the Magnetospheric Multiscale 2(MMS2)spacecraft.We used global magnetohydrodynamic(MHD)simulations of the Earth’s magnetosphere(publicly available from the NASA-CCMC[National Aeronautics and Space Administration–Community Coordinated Modeling Center])and local Vlasov equilibrium models(based on kinetic models for tangential discontinuities)to extract spatial profiles of the plasma and field variables at the Earth’s MP.The global MHD simulations used initial solar wind conditions extracted from the OMNI database at the time epoch when the MMS2 observes the MP.The kinetic Vlasov model used asymptotic boundary conditions derived from the same in situ MMS measurements upstream or downstream of the MP.The global MHD simulations provide a three-dimensional image of the magnetosphere at the time when the MMS2 crosses the MP.The Vlasov model provides a one-dimensional local view of the MP derived from first principles of kinetic theory.The MMS2 experimental data also serve as a reference for comparing and validating the numerical simulations and modeling.We found that the MP transition layer formed in global MHD simulations was generally localized closer to the Earth(roughly by one Earth radius)from the position of the real MP observed by the MMS.We also found that the global MHD simulations overestimated the thickness of the MP transition by one order of magnitude for three analyzed variables:magnetic field,density,and tangential speed.The MP thickness derived from the local Vlasov equilibrium was consistent with observations for all three of these variables.The overestimation of density in the Vlasov equilibrium was reduced compared with the global MHD solutions.We discuss our results in the context of future SMILE(Solar wind Magnetosphere Ionosphere Link Explorer)campaigns for observing the Earth’s MP.

Dynamical Dark Energy in Light of Cosmic Distance Measurements.Ⅱ.A Study Using Current Observations

We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark energy.In particular,a dynamical dark energy model whose equation of state crosses-1 is favored by observations.We also find that the Universe has started accelerating at a lower redshift than expected.

Thermosphere joint observations by TM-1 constellations and Swarm-B during the April 2023 geomagnetic storm

The response of thermosphere density to geomagnetic storms is a complicated physical process.Multi-satellite joint observations at the same altitude but different local times(LTs)are important for understanding this process;however,until now such studies have hardly been done.In this report,we analyze in detail the thermosphere mass density response at 510 km during the April 23−24,2023 geomagnetic storm using data derived from the TM-1(TianMu-1)satellite constellation and Swarm-B satellites.The observations show that there were significant LT differences in the hemispheric asymmetry of the thermosphere mass density during the geomagnetic storm.Densities observed by satellite TM02 at nearly 11.3 and 23.3 LTs were larger in the northern hemisphere than in the southern.The TM04 dayside density observations appear to be almost symmetrical with respect to the equator,though southern hemisphere densities on the nightside were higher.Swarm-B data exhibit near-symmetry between the hemispheres.In addition,the mass density ratio results show that TM04 nightside observations,TM02 data,and Swarm-B data all clearly show stronger effects in the southern hemisphere,except for TM04 on the dayside,which suggest hemispheric near-symmetry.The South-North density enhancement differences in TM02 and TM04 on dayside can reach 130%,and Swarm-B data even achieve 180%difference.From the observations of all three satellites,large-scale traveling atmospheric disturbances(TADs)first appear at high latitudes and propagate to low latitudes,thereby disturbing the atmosphere above the equator and even into the opposite hemisphere.NRLMSISE00 model simulations were also performed on this geomagnetic storm.TADs are absent in the NRLMSISE00 simulations.The satellite data suggest that NRLMSISE00 significantly underestimates the magnitude of the density response of the thermosphere during geomagnetic storms,especially at high latitudes in both hemispheres.Therefore,use of the density simulation of NRLMSISE00 may lead to large errors in satellite drag calculations and orbit predictions.We suggest that the high temporal and spatial resolution of direct density observations by the TM-1 constellation satellites can provide an autonomous and reliable basis for correction and improvement of atmospheric models.

Deep learning to estimate ocean subsurface salinity structure in the Indian Ocean using satellite observations

Accurately estimating the ocean subsurface salinity structure(OSSS)is crucial for understanding ocean dynamics and predicting climate variations.We present a convolutional neural network(CNN)model to estimate the OSSS in the Indian Ocean using satellite data and Argo observations.We evaluated the performance of the CNN model in terms of its vertical and spatial distribution,as well as seasonal variation of OSSS estimation.Results demonstrate that the CNN model accurately estimates the most significant salinity features in the Indian Ocean using sea surface data with no significant differences from Argo-derived OSSS.However,the estimation accuracy of the CNN model varies with depth,with the most challenging depth being approximately 70 m,corresponding to the halocline layer.Validations of the CNN model’s accuracy in estimating OSSS in the Indian Ocean are also conducted by comparing Argo observations and CNN model estimations along two selected sections and four selected boxes.The results show that the CNN model effectively captures the seasonal variability of salinity,demonstrating its high performance in salinity estimation using sea surface data.Our analysis reveals that sea surface salinity has the strongest correlation with OSSS in shallow layers,while sea surface height anomaly plays a more significant role in deeper layers.These preliminary results provide valuable insights into the feasibility of estimating OSSS using satellite observations and have implications for studying upper ocean dynamics using machine learning techniques.

Unprecedented JWST Observations Contest Cosmological Canons

After more than 18 months of nearly flawless operation,the James Webb Space Telescope(JWST)continues to deliver amazement,making unexpected discoveries,adding new wrinkles to known phenomena,and calling into question long-held theories of how the universe works.“The instruments are working amazingly well,in essentially all cases better than expected,”said Garth Illingworth,professor emeritus of astronomy and astrophysics at the University of California,Santa Cruz(CA,USA),and one of the three originators of the mission over three decades ago.“It has exceeded every one of its performance requirements,which is truly amazing when you think about how complex it is.”That complexity has included three decades of planning,design,and construction,followed by launch and maneuvering 1.5106 km from Earth to its second Lagrange(L2)orbit,unfolding and locking into position the 18 segments of its 6.5 m diameter main mirror,and deploying 8 motors,90 cables,and some 400 pulleys to unfurl its fragile sunshield[1,2].

Design and analysis of an advanced thermal management system for the solar close observations and proximity experiments spacecraft

In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.

In-situ observations of damage-fracture evolution in surrounding rock upon unloading in 2400-m-deep tunnels

The damage-fracture evolution of deep rock mass has obvious particularity,which is revealed in 2400-mdeep tunnels by field tests.The evolution of the excavation damaged zone depth is consistent with that of the fractured zone depth.The ratio of the excavation damaged zone depth to the excavation fractured zone depth is greater than 2.0 in a rock mass with both high strength and good integrity,but less than1.5 in a rock mass with lower strength or poor integrity.Zonal disintegration in a rock mass with high strength and fair integrity is more likely to occur when it contains more than two groups of primary fractures in damaged zones.Fractures develop outward in zonal disintegration but are totally different from the single-zone fracture,in which the fractures develop inward,and it is the starting position of the fractured zone when the excavation surface of the middle pilot is 7–9 m close to the pre-set borehole and it stops after the excavation surface of the baseplate is 11–14 m away.The most intense evolution occurs around 2–4 m from the pre-set borehole in the sidewall expansion stage.The research results provide a reference for the monitoring scheme and support design of CJPL-Ⅲin its future construction.

Twenty years of ocean observations with China Argo

The international Argo program,a global observational array of nearly 4000 autonomous profiling floats initiated in the late 1990s,which measures the water temperature and salinity of the upper 2000 m of the global ocean,has revolutionized oceanography.It has been recognized one of the most successful ocean observation systems in the world.Today,the proposed decade action“OneArgo”for building an integrated global,full-depth,and multidisciplinary ocean observing array for beyond 2020 has been endorsed.In the past two decades since 2002,with more than 500 Argo deployments and 80 operational floats currently,China has become an important partner of the Argo program.Two DACs have been established to process the data reported from all Chinese floats and deliver these data to the GDACs in real time,adhering to the unified quality control procedures proposed by the Argo Data Management Team.Several Argo products have been developed and released,allowing accurate estimations of global ocean warming,sea level change and the hydrological cycle,at interannual to decadal scales.In addition,Deep and BGC-Argo floats have been deployed,and time series observations from these floats have proven to be extremely useful,particularly in the analysis of synoptic-scale to decadal-scale dynamics.The future aim of China Argo is to build and maintain a regional Argo fleet comprising approximately 400 floats in the northwestern Pacific,South China Sea,and Indian Ocean,accounting for 9%of the global fleet,in addition to maintaining 300 Deep Argo floats in the global ocean(25%of the global Deep Argo fleet).A regional BGC-Argo array in the western Pacific also needs to be established and maintained.

Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

Do Observations during Patrolling Trips Detect Changes in Wildlife Presence & Diversity in National Parks?

Globally, mountains encompass spectacular landscapes and a great diversity of species. However, Savannah’s mountains in Sudan have been affected by the loss of diversity due to human activities and climate changes. Therefore, this study aims to assess changes in wildlife diversity in Jebel-Eldair Nation Park (JENP) based on only reports from patrolling activities, especially in the absence of regular wildlife monitoring programs. Reports of monthly wildlife observations during patrolling trips were used for the summer season in 2010 and 2018. Findings showed a moderate to high decline in the most important wildlife species (i.e. lion, wild dog, and crest porcupine). Six others are documented as rare species in reserve, including the civet, spotted hyena, striped hyena, jackal, seraval, and Siberian bird. Contrary and despite the diversity reduction, some species witnessed increases in their observation frequency, such as lesser kudu, caracal, monitor, and lunar bird. Moreover, human settlements, agricultural activities, and other anthropogenic factors were found to be the main drivers of biodiversity reduction in JENP. The study recommends adopting this method to detect changes in wildlife communities, especially in a situation of deficiency and lack of funding to conduct regular monitoring programs.

广州市2022年臭氧污染特征与成因分析

选取2022年O_(3)及其前体物观测数据、气象观测数据和ERA5再分析数据,结合基于观测的模型(OBM)和后向轨迹模型,分析了2022年广州市O_(3)污染特征,识别了O_(3)生成控制区及关键敏感型物种,并从O_(3)前体物排放、气象条件和区域传输3个方面开展了O_(3)污染成因分析.结果表明:广州市O_(3)生成以VOCs控制和NO_(x)-VOCs协同控制为主,现阶段VOCs和NO_(x)减排比例应不低于1:1;O_(3)生成对含氧VOCs最为敏感,其次是植物源VOCs(BVOCs)、烯烃、芳香烃和烷烃;2022年广州市O_(3)前体物NO_(x)和VOCs浓度同比下降14.7%和30.4%,但副高强盛、台风外围环流影响频繁叠加强辐射、高温、低湿等不利气象条件和区域传输抵消了广州市本地前体物减排的成效,造成O_(3)浓度上升,其中典型O_(3)污染过程(2022年9月16~22日)气流轨迹由西北、西南方向气团转变为东和东南方向气团,易受到来自周边城市区域传输影响.建议下一步持续推动NO_(x)减排,促进O_(3)对NO_(x)敏感性向正敏感性的转变,同时积极构建区域联防联控机制,降低区域传输贡献.

安徽省燃气炮人工增雨作业效果综合评估

选取2021—2023年安徽省81次燃气炮作业的双偏振天气雷达、雨量计等多源观测数据,综合评估燃气炮作业增雨效果并分析可能机理。结果显示:在降水开始前作业个例增雨效果较好,并伴有水平反射率因子Z_(H)、差分反射率Z_(DR)的增加和共极化相关系数ρ_(hv)的减少;降水开始后作业增雨效果欠佳。使用携带暖云催化剂的燃气炮作业后云体变化主要在零度层以下,且维持时间较短;使用携带冷云催化剂的燃气炮作业后暖云区和冷云区均有明显变化,且作业影响持续时间更长。燃气炮作业过程中雷达速度谱宽增大,可能是作业引起气流涡旋的增加所导致。统计结果显示:增雨的显著性与作业时长呈负相关,作业时长与Z_(DR)增量呈负相关,过量播撒会导致减雨;增雨的显著性与作业前影响区雨量呈负相关;增雨量与Z_(H)、中低层风速、风切变呈正相关,与高层风速呈负相关。

含风光出力随机性的独立微电网二次频率控制

针对风、光发电随机性的问题,提出一种考虑新能源减载参与二次调频的模型预测控制方法。建立包含随机功率扰动的扩展状态矩阵,采用卡尔曼滤波估算随机未知扰动;依据风、光最大可用功率,建立实时变约束,避免机组功率越限;设置合理的权重系数,优先风、光发电出力参与二次调频;通过求解变约束二次规划问题,获得各个机组的优化调频功率。最后,建立含多个光伏、风电的微电网模型,在不同场景下与常规二次调频方法进行对比仿真。仿真结果表明,所提方法能提高系统频率恢复速度,减小系统频率波动,尤其在风、光发电剧烈波动场景下。

中年男性精子DNA碎片率对体外受精-胚胎移植妊娠结局的影响

目的探讨中年男性精子DNA碎片率(DFI)与精液质量和体外受精-胚胎移植妊娠结局的关系。方法共收集180例接受常规体外受精-胚胎移植治疗且男性年龄>38岁的精液标本。根据DFI的阈值分成(<30%和≥30%)两组。主要测量指标包括:常规精液参数、激素水平、DFI、受精率、优质胚胎率、临床妊娠率等。结果通过比较分析发现,DFI与男性卵泡刺激素(FSH)、精子活力、精子形态密切相关,且精子活力随着DFI水平的升高而下降(P<0.05);当DFI≥30%时,优质胚胎率下降(P<0.05),但两组的临床妊娠率差异无显著性(P>0.05)。结论DFI可以作为中年男性精液常规分析的重要参考指标,虽然DFI影响优质胚胎率,但与辅助生殖治疗的临床妊娠结局无关。

天文应用红外焦平面读出电路研究

成功设计了一款天文应用的640×512短波红外焦平面读出电路。由于红外天文观测具有极低背景辐射、光子通量低的特点,为了实现探测器的高信噪比,需要降低器件的暗电流和电路噪声。电路采用有效的功耗管理策略,在保证电路正常工作的前提下尽可能地降低电路功耗以减小电路辉光对器件暗电流的影响。同时,研究非破坏性读出的数字功能,实现了超长的积分时间和信号的多帧累积,并作为一种斜坡采样的策略有效地降低读出噪声。短波HgCdTe焦平面的测试结果符合理论设计预期,开启电路非破坏性读出功能,设置6 000 s的积分时间,当电路功耗调低至14.04 mW时暗电流为0.9 e-·pixel^(-1)·s^(-1)。读出噪声在两档增益下分别为50 e-(10 fF)和27 e-(5 fF),非线性度低于0.1%。

永磁同步电机交直轴电流解耦控制方法综述

该文归纳整理永磁同步电机交直轴电流解耦控制方法,分析各种解耦方法的思想来源、脉络体系和演变过程,论证不同解耦方法的解耦本质和内在联系。从整体和局部视角出发,建立解耦问题的思维架构,概括出对角化解耦、抗干扰解耦和逆系统解耦3类方法。3类方法依次体现出模型依赖性降低、鲁棒性增强、算法复杂度提高的趋势,呈现出从“模型论”向“控制论”过渡的技术发展路线。讨论参数不确定条件下各种解耦控制方法的鲁棒性,指出将解耦方法与先进控制算法、扰动观测技术、系统辨识方法以及人工智能方法相结合,并充分利用已知的模型信息,有利于提升交直轴电流解耦效果,增强系统鲁棒性,减弱单一观测器、控制器、滤波器等的设计难度与参数整定要求,有助于实现系统全局最优。最后,对永磁同步电机交直轴电流解耦问题的关键技术、应用与发展做出展望。

大气协同观测网络与大数据平台建设

野外科学观测研究站是重要的国家科技创新基地之一,也是国家创新体系的重要组成部分。面向大气科学研究对第一手野外观测数据的迫切需求,本文在充分调研中国科学院大气物理研究所野外观测台站的基础上,详细阐述了“大气协同观测网络与大数据平台建设”项目的科学意义、研究内容、实施方案、预期成果与展望等。该项目拟通过顶层设计和优化布局,在有限投入的情况下最大限度地挖掘和利用现有各野外台站资源优势,进行联网协同观测试验,研发时空连续、高精度、高质量的大数据产品,为地球系统模式中关键物理过程参数化方案的改进和优化提供第一手宝贵的数据支撑,服务于国家科技原始创新战略。

基于多阶反馈重构的微电网端口变换器自抗扰策略

直流微电网低压负载侧电能稳定供应是新型电力系统中新能源有效消纳的重要保障。针对微电网供能枢纽变换器受扰情况下输出不稳定的问题,提出了一种观测器状态变量重构补偿的改进型自抗扰策略。首先,通过剖析自抗扰框架下无法避免的结构问题,推导出观测误差精准范式,并对扰动观测变量进行重构补偿,实现对总扰动的快速跟踪和消除。然后,进一步对改进策略在稳定性能、跟踪性能、抗扰性能、鲁棒性能4个维度进行理论分析,验证了该策略的正确性与有效性。最后,利用数字仿真和物理实验模拟实际工况进行对比分析,验证了该策略在微电网系统多种内外不确定扰动下均具有较好的动态性能。

我国海洋观测装备“卡脖子”问题的破解对策建议

该文中“卡脖子”问题是指我国海洋观测装备在发展过程中遇到的瓶颈和限制,阻碍了海洋科学研究和海洋资源利用。该文对我国海洋观测装备的发展进行需求分析,从海洋观测平台和海洋传感器的发展两个方面介绍我国海洋观测装备发展的现状;从创新能力、成果转化能力、国产化应用、技术标准和测试试验等方面分析“卡脖子”问题出现的原因,针对这些问题提出加强海洋仪器设备应用的调研和评估、提升设备的精准度和可靠性、进行海洋仪器设备攻关加快研发和推广、完善海洋标准和试验测试体系等一系列措施建议。有助于提高我国海洋观测装备的整体技术水平,促进海洋科技的进步,推动我国在海洋观测领域的可持续发展。

基于主动悬架的整车车身姿态控制策略研究

针对车辆在行驶过程中产生的车身姿态失衡问题,提出了一种基于姿态补偿的主动悬架整车车身姿态控制策略。在建立整车七自由度动力学模型,并基于随机路面进行实车试验验证整车模型的准确性的基础上,构建了模型预测控制器,根据状态观测器估计的各信号求解各个悬架的垂向控制力以衰减车辆垂向振动;进而以模糊算法为基础设计车身姿态补偿控制策略,使电磁直线作动器产生反作用力以抑制车身姿态恶化。选取某型号直线电机作为主动悬架力源,将垂向控制力与姿态补偿力合并得到各悬架控制所需电磁作动力,以此计算电机所需目标电流,并通过MATLAB/Simulink平台对主动悬架系统进行仿真。仿真结果表明:所提出的基于主动悬架的整车车身姿态控制策略在不影响车辆垂向控制效果的基础上,能够大幅降低车辆质心侧倾角和俯仰角的均方根值,车身姿态得到有效控制。