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Zeeman decoherence effect of trapped ^(199)Hg^(+) ion Ramsey spectra

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Chinese Physics B 2024年第11期33卷 272-277页

作者： ge liu Hao liu Yihe Chen Jian Wang Shuhong Huang Chengbin Li Lei She Key Laboratory of Atomic Frequency Standards (KLAFS) Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

In the ^(199)Hg^(+) ion microwave clock,the Zeeman decoherence effect caused by the overlapping of Zeeman sidebands and the radial secular motion sidebands will decrease the contrast of the Ramsey fringe,thus reducing the signal-to-noise ratio of the *** this paper,the Zeeman decoherence effect is analyzed theoretically and investigated experimentally.A simplified model is built to describe the Ramsey spectral probability,in which the transverse relaxation time T2 is introduced to characterize the influence of the Zeeman decoherence effect *** experiments were carried out on a linear quadrupole trap ^(199)Hg^(+) ion *** results show that the probability model matches well with the experimental data,and the magnetic field value should be more than 150 mGs(1 Gs=10^(-4) T)to avoid the Zeeman decoherence effect.

关键词： ^(199)Hg^(+)ion microwave clock Zeeman decoherence transverse relaxation time

A Dipole Pattern of Summer Precipitation over Mid-high Latitude Asia and Related Snow Cover Anomalies in the Preceding Spring

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Atmospheric and Oceanic Science Letters 2014年第4期7卷 364-368页

作者： HAN Jin-Ping liu ge XIN Yu-Fei Chinese Academy of Meteorological Sciences

A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China(MNC) region and the West Siberian Plain(WSP), is found to be clear and stable on both interdecadal and interannual scales during 1981–2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River(HR) region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are needed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole.

关键词： precipitation snow cover climatic anomaly dipole

genesis of the Jincheng Gold Deposit in Luoshan County, Henan Province, China

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Acta geologica Sinica(English Edition) 2017年第S1期91卷 181-182页

作者： liu Hong liu ge KE Changhui Chengdu Center China Geological Survey Faculty of Earth Resources China University of Geosciences geological survey of Xinjiang Autonomous Region Institute of Mineral Resources Chinese Academy of Geological Sciences

1 Introduction The Tongbai-Dabie area has experienced multistage plate subduction-collision activities,resulting in the development of a series of nearly EW-trending ductileshear zones with different levels,scales,and... 详细信息

关键词： China genesis of the Jincheng Gold Deposit in Luoshan County Henan Province

Influence of pore structure heterogeneity on channeling channels during hot water flooding in heavy oil reservoir based on CT scanning

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Petroleum Science 2024年第4期21卷 2407-2419页

作者： Qing-Jun Du Hao-Yu Zheng Jian Hou Yong-ge liu Jian-Fang Sun Dong Zhao State Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao266580ShandongPR China School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao266237ShandongPR China Petroleum Exploration and Production Research Institute SINOPECBeijing10083PR China

Hot water flooding is an effective way to develop heavy oil ***,local channeling channels may form,possibly leading to a low thermal utilization efficiency and high water cut in the *** pore structure heterogeneity is an important factor in forming these *** study proposes a method that mixes quartz sand with different particle sizes to prepare weakly heterogeneous and strongly heterogeneous models through which hot water flooding experiments are *** the experiments,computer tomography(CT)scanning identifies the pore structure and micro remaining oil saturation distribution to analyze the influence of the pore structure heterogeneity on the channeling *** oil saturation reduction and average pore size are divided into three levels to quantitatively describe the relationship between the channeling channel distribution and pore structure *** zone where oil saturation reduction exceeds 20%is defined as a channeling *** scanning area is divided into 180 equally sized zones based on the CT scanning images,and threedimensional(3D)distributions of the channeling channels are *** micro remaining oil distribution patterns are proposed,and the morphology characteristics of micro remaining oil inside and outside the channeling channels are *** results show that hot water flooding is more balanced in the weakly heterogeneous model,and the oil saturation decreases by more than 20%in most zones without narrow channeling channels *** the strongly heterogeneous model,hot water flooding is unbalanced,and three narrow channeling channels of different lengths *** the weakly heterogeneous model,the oil saturation reduction is greater in zones with larger *** distribution range of the average pore size is larger in the strongly heterogeneous *** network remaining oil inside the channeling channels is less than outside the channeling channels,and the hot water convert

关键词： Heavy oil Hot water flooding Pore structure Channeling channels CT scanning

Persistence of Snow Cover Anomalies over the Tibetan Plateau and the Implications for Forecasting Summer Precipitation over the Meiyu-Baiu Region

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Atmospheric and Oceanic Science Letters 2014年第2期7卷 115-119页

作者： liu ge WU Ren-Guang ZHANG Yuan-Zhi Chinese Academy of Meteorological Sciences Institute of Space and Earth Information Science and Shenzhen Research Institute the Chinese University of Hong Kong National Astronomical Observatories Chinese Academy of Sciences

The present reported study investigated the persistence of snow anomalies over the Tibetan Plateau(TP) from the preceding seasons to summer and the relationship between the previous snow cover anomaly and summer precipitation over East Asia. The results showed that, relative to other snow indices, such as the station observational snow depth(SOSD) index and the snow water equivalent(SWE) index, the snow cover area proportion(SCAP) index calculated from the SWE and the percentage of visible snow of the Equal-Area Scalable Earth Grids(EASE-grids) dataset has a higher persistence in interannual anomalies, particularly from May to summer. As such, the May SCAP index is significantly related to summer precipitation over the Meiyu-Baiu region. The persistence of the SCAP index can partly explain the season-delayed effect of snow cover over the TP on summer rainfall over the Meiyu-Baiu region besides the contribution of the soil moisture bridge. The preceding SST anomaly in the tropical Indian Ocean and ENSO can persist through the summer and affect the summer precipitation over the Meiyu-Baiu region. However, the May SCAP index is mostly independent of the simultaneous SSTs in the tropical Indian Ocean and the preceding ENSO and may affect the summer precipitation over the Meiyu-Baiu region independent of the effects of the SST anomalies. Therefore, the May SCAP over the TP could be regarded as an important supplementary factor in the forecasting of summer precipitation over the Meiyu-Baiu region.

关键词： snow cover Tibetan Plateau Meiyu precipitation forecast

Differentiation of Algal Blooms and Aquatic Vegetation in Chinese Lakes Using Modified Vegetation Presence Frequency Index Method

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Chinese geographical Science 2022年第5期32卷 792-807页

作者： PU Jing SONG Kaishan liu ge WEN Zhidan FANG Chong HOU Junbing LV Yunfeng College of geographical Sciences Changchun Normal UniversityChangchun 130032China Northeast Institute of geography and Agro ecology Chinese Academy of ScienceChangchun 130102China

Algal blooms in lakes have become a common global environmental problem. Nowadays, remote sensing is widely used to monitor algal blooms in lakes due to the macroscopic, fast, real-time characteristics. However, it is often difficult to distinguish between algal blooms and aquatic vegetation due to their similar spectral characteristics. In this paper, we used modified vegetation presence frequency index(VPF) based on Moderate-resolution Imaging Spectroradiometer(MODIS) imagery to distinguish algal blooms from aquatic vegetation, and analyzed the spatial and temporal variations of algal blooms and aquatic vegetation from a phenological perspective for five large natural lakes with frequent algal bloom outbreaks in China from 2019 to 2020. We simplified the VPF method to make it with a higher spatial transferability so that it could be applied to other lakes in different climatic zones. Through accuracy validation, we found that the modified VPF method can effectively distinguish between algal blooms and aquatic vegetation, and the results vary from lake to lake. The highest accuracy of 97% was achieved in Hulun Lake, where the frequency of algal outbreaks is low and the extent of aquatic vegetation is stable, while the lowest accuracy of 76% was achieved in Dianchi Lake, which is rainy in summer and the lake is small. Analyses suggests that the time period when algal blooms occur most frequently might not coincide with that when they have the largest area. However, in most cases these two are close in terms of time period. The modified VPF method has a broad scope of application, is easy to implement, and has a high practical value. Furthermore, the method could be established using only a small amount of measured data, which is useful for water quality monitoring on large spatial scales.

关键词： algal blooms aquatic vegetation modified vegetation presence frequency index(VPF) phenology lake

Towards More Snow Days in Summer since 2001 at the Great Wall Station,Antarctic Peninsula:The Role of the Amundsen Sea Low

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Advances in Atmospheric Sciences 2020年第5期37卷 494-504页

作者： Minghu DING Wei HAN Tong ZHANG Xiaoyuan YUE Jeremy FYKE ge liu Cunde XIAO State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Fluid Dynamics and Solid Mechanics Group Los Alamos National LaboratoryLos AlamosNew Mexico 87545USA Associated Engineering Group LtdVernonBritish Columbia V1T 9P9Canada State Key Laboratory of Earth Surface and Resource Ecology Beijing Normal UniversityBeijing 100875China Beijing Meteorological Observation Center Beijing 100176China

The variation in the precipitation phase in polar regions represents an important indicator of climate change and *** studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?***,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the *** total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air ***,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during *** study points out a supplementary factor for the climate variation on the AP.

关键词： precipitation phase Great Wall Station Amundsen Sea Low

Cooling effect of convection-intensifying composite embankment with air doors on permafrost

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Research in Cold and Arid Regions 2014年第4期6卷 372-377页

作者： Hong Sun XiuRun ge FuJun Niu ge liu JinZhao Zhang School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences CCCC First Highway Consultants Co. Ltd.

One of the main construction problems in permafrost regions is protecting permafrost thermal stability. Although ventilating ducts and crushed-rock layers were successfully used in railway embankment construction, their effects might not meet large-width expressway requirements. The convection-intensifying composite embankment composed of perforated ventilation ducts and crushed-rock layers was numerically studied to investigate its cooling effects. Adopting a numerical model, the temperature fields for two kinds of composite embankment with and without air doors were analyzed considering air flow and heat transfer characteristics in porous media. The results show that wind velocity in the crushed-rock zone is intensified by the perforated ventilation duct. The underlying permafrost temperature obviously decreases, and the 0 °C isotherm position rises significantly due to composite embankment. The composite embankment with air doors is more effective than that without air doors. Therefore, the new convection-intensifying composite embankment is potentially a highly efficient cooling measure for construction in permafrost regions.

关键词： cooling effect composite embankment permafrost convection-intensifying air doors

Enhanced nitrogen removal at low temperature with mixed anoxic/oxic process

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Water Science and Engineering 2023年第1期16卷 67-75页

作者： Xiang-kun Li Ying-jun Yang Gai-ge liu Dou-dou Sun Xiao-chen Ma School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China School of Environment Harbin Institute of TechnologyHarbin 150090China

Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low *** results showed that the addition of the fillers improved the treatment effect of each index in the *** an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,*** an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,*** results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low *** microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal ***,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively.

关键词： Domestic sewage Low temperature Mixed A/O process Nitrogen removal Bacterial community structure