检索结果-南通市图书馆

In vitro iron enrichment experiments in the Prydz Bay, the Southern Ocean: A test of the iron hypothesis

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2009年第9期52卷 1426-1435页

作者： sun Song PU XinMing ZHANG YongShan Key Laboratory of Marine Ecology and environmental sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China Marine Ecology Research Center First Institute of OceanographyState Oceanic AdministrationQingdao 266061China

In "high nitrate, low chlorophyll" (HNLC) ocean regions, iron has been typically regarded as the limiting factor for phytoplankton production. This "iron hypothesis" needs to be tested in various oceanic environments to understand the role of iron in marine biological and biogeochemical processes. In this paper, three in vitro iron enrichment experiments were performed in Prydz Bay and at the polar Front north of the Ross Sea, to study the role of iron on phytoplankton production. At the polar Front of Ross Sea, iron addition significantly (P0.05, Student's t-test) as a consequence of iron addition was observed. These results confirmed the limiting role of iron in the Ross Sea and indicated that iron was not the primary factor limiting phytoplankton growth in Prydz Bay. Because the light environment for phytoplankton was enhanced in experimental bottles, light was assumed to be responsible for the rapid growth of phytoplankton in all treatments and to be the limiting factor controlling field phytoplankton growth in Prydz Bay. During the incubation experiments, nutrient consumption ratios also changed with the physiological status and the growth phases of phytoplankton cells. When phytoplankton growth was stimulated by iron addition, N was the first and Si was the last nutrient which absorption enhanced. The Si/N and Si/P consumption ratios of phytoplankton in the stationary and decay phases were significantly higher than those of rapidly growing phytoplankton. These findings were helpful for studies of the ma- rine ecosystem and biogeochemistry in Prydz Bay, and were also valuable for biogeochemical studies of carbon and nutrients in various marine environments.

关键词： iron limitation iron hypothesis Southern Ocean Prydz Bay nutrient consumption ratio

Spinel-type bimetal sulfides derived from Prussian blue analogues as efficient polysulfides mediators for lithium-sulfur batteries

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第12期32卷 4063-4069页

作者： Ruijian Li Zhe Bai Wenshuo Hou Jinshuo Qiao Wang sun Yu Bai Zhenhua Wang Kening sun Beijing Key Laboratory for Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China Collaborative Innovation Center of Electric Vehicles in Beijing Beijing 100081China

More and more attentions have been attracted by lithium-sulfur batteries(Li-S), owing to the high energy density for the increasingly advanced energy storage system. While the poor cycling stability, due to the inherent polysulfide shuttle, seriously hampered their practical application. Recently, some polar hosts,like single metal oxides and sulfides, have been employed as hosts to interact with polysulfide intermediates. However, due to the inherent poor electrical conductivity of these polar hosts, a relatively low specific capacity is obtained. Herein, a spinel-type bimetal sulfide NiCo_(2)S_(4)through a Prussian blue analogue derived methodology is reported as the novel host of polysulfide, which enables highperformance sulfur cathode with high Coulombic efficiency and low capacity decay. Notably, the Li-S battery with NiCo_(2)S_(4)-S composites cathode still maintains a capacity of 667 m Ah/g at 0.5 Cafter 300 cycles, and 399 m Ah/g at 1 C after 300 cycles. Even after 300 cycles at the current density of 0.5C, the capacity decays by 0.138% per cycle at high sulfur loading about 3 mg/cm;. And the capacity decays by0.026% per cycle after 1000 cycles, when the rate is 1C. More importantly, the cathode of Ni Co_(2)S_(4)-S composite shows the outstanding discharge capacity, owing to its good conduction, high catalytic ability and the strong confinement of polysulfides.

关键词： Polysulfide shuttle NiCo_(2)S_(4)L Ithium-Sulfur batteries

Evaluation of Arctic Sea-ice Cover and Thickness Simulated by MITgcm

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric sciences 2021年第1期38卷 29-48页

作者： Fei ZHENG Yue sun Qinghua YANG Longjiang MU International Center for Climate and environment science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China university of Chinese Academy of sciences Beijing 100049China School of Atmospheric sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Alfred Wegener institute Helmholtz Centre for Polar and Marine ResearchBremerhaven 27515Germany

A regional Arctic Ocean configuration of the Massachusetts institute of technology General Circulation Model(MITgcm)is applied to simulate the Arctic sea ice from 1991 to *** simulations are evaluated by comparing them with observations from different *** results show that MITgcm can reproduce the interannual and seasonal variability of the sea-ice extent,but underestimates the trend in sea-ice extent,especially in *** ice concentration and thickness distributions are comparable to those from the observations,with most deviations within the observational uncertainties and less than 0.5 m,*** simulated sea-ice extents are better correlated with observations in September,with a correlation coefficient of 0.95,than in March,with a correlation coefficient of ***,the distributions of sea-ice concentration are better simulated in March,with higher pattern correlation coefficients(0.98)than in *** the model underestimates the atmospheric influence on the sea-ice evolution in March,deviations in the sea-ice concentration arise at the ice edges and are higher than those in *** contrast,when the model underestimates the oceanic boundaries’influence on the September sea-ice evolution,disagreements in the distribution of the sea-ice concentration and its trend are found over most marginal seas in the Arctic *** uncertainties of the model,whereby it fails to incorporate the atmospheric information in March and oceanic information in September,contribute to varying model errors with the seasons.

关键词： Arctic sea ice MITgcm simulation and evaluation sources of model error

基于非线性尺度空间与极坐标分布熵的GIS局放特征提取方法

在线全文

学校读者我要写书评

暂无评论

电网技术 2024年第8期48卷 3525-3533,I0155页

作者：钱庆林孙炜昊王真路永玲李玉杰江秀臣上海交通大学电子信息与电气工程学院上海市闵行区200240 国网江苏省电力有限公司电力科学研究院江苏省南京市211100

气体绝缘组合电器(gas insulated switchgear,GIS)局部放电(partial discharge,PD)缺陷类型的准确识别对电力设备的状态评估与故障诊断至关重要,为了解决PD模式识别中特征提取准确性不足的问题,该文提出一种基于极坐标分布熵优化的非线... 详细信息

气体绝缘组合电器(gas insulated switchgear,GIS)局部放电(partial discharge,PD)缺陷类型的准确识别对电力设备的状态评估与故障诊断至关重要,为了解决PD模式识别中特征提取准确性不足的问题,该文提出一种基于极坐标分布熵优化的非线性尺度空间特征(KAZE)提取方法。首先,对光、电单参量图谱进行非下采样轮廓波变换(non-subsampled contourlet transform,NSCT),得到包含信息更丰富的光电融合图谱;然后,利用KAZE算法提取图谱典型特征点,并依据相位、幅值、尺度信息将特征点发散至极坐标,提取子区域分布熵构成特征向量;最后,将特征信息带入经自适应增强算法(Adaboost)优化的长短期记忆网络(long short-term memory,LSTM)进行模式识别验证,并与KAZE法、统计参数法、卷积神经网络(convolutional neural networks,CNN)进行对比。结果表明,该文提出的特征提取方法在不同训练集分布下均可达到较高的识别率,最高可达91%,相较于统计参数法、CNN分别提升8.8%和4.4%,可以为提高GIS局部放电特征提取准确性提供参考。

关键词：气体绝缘组合电器局部放电非线性尺度空间特征提取图像融合分布熵模式识别

维普期刊数据库博看期刊

Instability waves and low-frequency noise radiation in the subsonic chevron jet

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第3期34卷 421-430页

作者： Lingke Ran Chuangchao Ye Zhenhua Wan Haihua Yang Dejun sun Department of Modern Mechanics University of Science and Technology of ChinaHefei 230027China institute of Applied Physics and Computational Mathematics Beijing 100088China

Spatial instability frequency noise radiation at waves associated with low- shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier-Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear, and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at down- stream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.

关键词： Instability waves Chevron jet Wavepacket Far-field noise

1993-2022年罗斯海夏季感热和潜热通量的年际变化

在线全文

学校读者我要写书评

暂无评论

极地研究 2024年第2期36卷 211-220页

作者：姚洁何海伦孙群于乐江张艺杰于璐莎李学琪天津科技大学海洋与环境学院天津300222 卫星海洋环境动力学国家重点实验室自然资源部第二海洋研究所浙江杭州310012 南方海洋科学与工程广东省实验室(珠海) 广东珠海519082 中国极地研究中心(中国极地研究所) 上海200136

大气下垫面感热和潜热通量是海-冰-气耦合系统中重要的环境变量。基于欧洲中期天气预报中心(ECMWF)提供的第五代再分析资料(ERA5),本文研究了1993-2022年南大洋罗斯海夏季月份感热和潜热通量的年际变化。1月气候态分布显示,感热和潜热... 详细信息

大气下垫面感热和潜热通量是海-冰-气耦合系统中重要的环境变量。基于欧洲中期天气预报中心(ECMWF)提供的第五代再分析资料(ERA5),本文研究了1993-2022年南大洋罗斯海夏季月份感热和潜热通量的年际变化。1月气候态分布显示,感热和潜热通量绝对值在空间上表现为陆架高海盆低。感热和潜热通量异常场的经验正交函数分析表明,前三模态累积方差贡献率超过75%,第一模态空间型主要强调区域一致变化,且第一模态时间系数存在约2.9年和4.4年的变化周期。陆架区感热和潜热通量的年际变化具有非常高的相关性。另一方面,感热通量与风速和海-气温差具有较高相关性,潜热通量与风速和海-气比湿差具有较高相关性,这些相关系数具有明显的空间分布。研究量化了南大洋罗斯海夏季感热和潜热通量年际变化,初步探讨了感热和潜热通量年际变化影响因素,可为南大洋罗斯海海-冰-气相互作用研究提供参考。

关键词：感热和潜热通量 ERA5 年际变化罗斯海南大洋

Electrically driven motion, destruction, and chirality change of polar vortices in oxide superlattices

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2022年第3期65卷 77-84页

作者： Pan Chen Congbing Tan Zhexin Jiang Peng Gao Yuanwei sun Lifen Wang Xiaomei Li Ruixue zhu Lei Liao Xu Hou Ke Qu Ning Li Xiaomin Li Zhi Xu Kaihui Liu Wenlong Wang Jinbin Wang Xiaoping Ouyang Xiangli Zhong Jie Wang Xuedong Bai Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China International Center for Quantum Materials Electron Microscopy LaboratorySchool of PhysicsPeking UniversityBeijing 100871China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Collaborative Innovation Center of Quantum Matter Beijing 100871China School of Physical sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China State Key Laboratory for Artificial Microstructure&Mesoscopic Physics School of PhysicsPeking UniversityBeijing 100871China School of Materials science and Engineering Xiangtan UniversityXiangtan 411105China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang UniversityHangzhou 310027China

Topological polar vortices, which are electric analogs of magnetic objects, present great potential in applications of future nanoelectronics because of their nanometer size, anomalous dielectric response, and chirality. To enable the functionalities, it is prerequisite to manipulate the polar states and chirality by using external stimuli. Here, we probe the evolutions of polar state and chirality evolutions of topological polar vortices in Pb TiO;/Sr TiO;superlattices under an electric field by using atomically resolved in situ scanning transmission electron microscopy and phase-field simulations. We find that, under electric field, the chiral vortex cores can be moved laterally to form close-pair structures, transform into a/c domain stripes, and finally become a nonchiral c-domain. Such transition is reversible and spontaneous after bias removal. Interestingly, during switching and backswitching events, the vortex rotation can be changed, offering a potential strategy to manipulate vortex chirality. The revealed dynamic behavior of individual polar vortices at the atomic scale provides fundamentals for future device applications.

关键词： chirality polar vortex ferroelectrics in situ transmission electron microscopy phase-field simulations

The Nano Research Young Innovators Awards in bio-inspired nanomaterials

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第2期17卷 417-425页

作者： Jun Chen Shuotao Wang Department of Bioengineering University of CaliforniaLos AngelesLos AngelesCA 90095USA Key Laboratory of Bio-inspired Materials and Interfacial science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China

Nano Research Young Innovators(NR45)Awards are designed to acknowledge and celebrate the achievements of young researchers under 45 years of *** individuals have made significant contributions to the field of nanoscience and *** the inaugural NR45 Awards in 2018,the journal's editorial board has recognized over a hundred innovators specializing in nanobiotechnology,nano energy,two-dimensional materials,and *** focus of the 2023 NR45 Awards is on bioinspired nanomaterials,acknowledging thirty-three outstanding young innovators for their extraordinary contributions in developing these materials with applications spanning clean energy,human healthcare,monitoring,and disease treatments,as shown in *** extend our heartfelt congratulations to all the 33 NR45 Awardees in 2023!

关键词： journal materials contributions

Organic geochemical record of paleocivilization at the Yuchisi Site, Mengcheng, Anhui, china

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2006年第B8期25卷 16-16页

作者： Jianjun WANG liguang sun Libin XU institute of polar environment School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China Key Laboratory of Global Change and Marine-Atmospheric Chemistry SOA Xiamen 361005 China