Diurnal Variations of Air Pollution and Atmospheric Boundary Layer Structure in Beijing During Winter 2000／2001   总被引：4，自引：0，他引：4  

ZHOU Li  XU Xiangde  DING Guoan  ZHOU Mingyu  CHENG Xinghong 《大气科学进展》2005,22(1):126-132

The diurnal variations of gaseous pollutants and the dynamical and thermodynamic structures of the atmospheric boundary layer (ABE) in the Beijing area from January to March 2001 are analyzed in this study using data from the Beijing City Air Pollution Observation Field Experiment (BECAPEX). A heavy pollution day (22 February) and a good air quality day (24 February) are selected and individually analyzed and compared to reveal the relationships between gaseous pollutants and the diurnal variations of the ABL. The results show that gaseous pollutant concentrations exhibit a double-peak-double-valley-type diurnal variation and have similar trends but with different magnitudes at different sites in Beijing. The diurnal variation of the gaseous pollutant concentrations is closely related to (with a 1-2 hour delay of) changes in the atmospheric stability and the mean kinetic energy in the ABL.  相似文献   

Effects of environment factors on initiation of sperm motility in sea cucumber Apostichopus japonicus (Selenka)     

Li Yu  Mingyu Shao  Zhenmin Bao  Jingjie Hu  Zhifeng Zhang 《中国海洋大学学报(英文版)》2011,10(2):165-169

Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.  相似文献   

A STATISTICAL ANALYSIS OF SODAR DATA DETECTED IN YANSHAN MOUNTAIN AREA,BEIJING     

L&#;Naiping  Zhou Mingyu  Su Lirong  Chen Yanjuan 《Acta Meteorologica Sinica》1989,3(5):645-652

According to the characteristics of sodar echo,a classified method for temperature stratification is given.By using sodar data observed in Yanshan Mountain area in Beijing,the statistical characteristics for the heightof inversion layer,thermal plume,and the depth of mixed layer are compared.Finally,the appearancefrequency for stable,unstable and neutral stratification is analyzed.  相似文献   

洋面动量、感热和潜热通量计算的研究   总被引：3，自引：1，他引：3       下载免费PDF全文

邵庆秋  周明煜  李兴生 《大气科学》1991,15(3):9-17

整体传输公式是一种常用的计算洋面海气通量的方法。在作气候平均计算时,存在两种平均方法:方法一F_1=AB及方法二F_2=AB。显然,方法一是合理的,而方法二是对方法一的近似。本文利用COADS资料针对不同的平均时间计算分析了方法二对方法一的近似程度,结果表明:利用方法二计算长期气候平均,平滑时间超过5天则对计算结果必须进行订正;对感热和潜热通量,月平均方法二在20％的精度内可代替方法一,而旬平均方法二则可在10％的精度内代替方法一;动量通量月平均和旬平均精度分别为40％和20％。因此方法二在计算月平均动量通量时必须作订正,或直接用方法一进行计算,本文同时计算比较了1972年(E1 Nino年)和1975年(非E1 Nino年)太平洋洋面的各项能量及总能量收支,发现1972年洋面能量收支年变化幅度比1975年小得多,其差别主要决定于感热和潜热的变化。  相似文献   

对流边界层中夹卷作用的研究     

鲁明之  周明煜 《大气科学》1988,12(4):420-429

本文采用从大涡旋模拟结果得到的湍流交换系数K,用K模式对对流边界层的结构、发展以及其顶部夹卷作用进行了研究。结果表明:边界层顶部夹卷对对流边界层的发展有重要影响;另外,我们把这种从理论上来说仅适用于温度、湿度等标量的湍流交换系数K应用到风速分量的计算中,也取得较好效果。  相似文献   

Ore Genesis of the Lunwei Granite‐Related Scheelite Deposit in the Wuyi Metallogenic Belt,Southeast China: Constraints from Geochronology,Fluid Inclusions,and H–O–S Isotopes          下载免费PDF全文

Hui Wang  Chengyou Feng  Yiming Zhao  Mingyu Zhang  Runsheng Chen  Jinliang Chen 《Resource Geology》2016,66(3):240-258

A granite‐related scheelite deposit has been recently discovered in the Wuyi metallogenic belt of southeast China. The veinlet–disseminated scheelite occurs mainly in the inner and outer contact zones of the porphyritic biotite granite, spatially associated with potassic feldspathization and silicification. Re–Os dating of molybdenite intergrowths with scheelite yield a well‐constrained isochron age of 170.4 ± 1.2 Ma, coeval with the LA–MC–ICP–MS concordant zircon age of porphyritic biotite granite (167.6 ± 2.2 Ma), indicating that the Lunwei W deposit was formed in the Middle Jurassic (~170 Ma). We identify three stages of ore formation (from early to late): (I) the quartz–K‐feldspar–scheelite stage; (II) the quartz–polymetallic sulfide stage; and (III) the quartz–carbonate stage. Based on petrographic observations and microthermometric criteria, the fluid inclusions in the scheelite and quartz are determined to be mainly aqueous two‐phase (liquid‐rich and gas‐rich) fluid inclusions, with minor gas‐pure and CO₂‐bearing fluid inclusions. Ore‐forming fluids in the Lunwei W deposit show a successive decrease in temperature and salinity from Stage I to Stage III. The homogenization temperature decreases from an average of 299 °C in Stage I, through 251 °C in Stage II, to 212 °C in Stage III, with a corresponding change in salinity from an average of 5.8 wt.%, through 5.2 wt.%, to 3.4 wt.%. The ore‐forming fluids have intermediate to low temperatures and low salinities, belonging to the H₂O–NaCl ± CO₂ system. The δ¹⁸O_H2O values vary from 1.8‰ to 3.3‰, and the δD_V‐SMOW values vary from –66‰ to –76‰, suggesting that the ore‐forming fluid was primarily of magmatic water mixed with various amounts of meteoric water. Sulfur isotope compositions of sulfides (δ³⁴S ranging from –1.1‰ to +2.4‰) and Re contents in molybdenite (1.45–19.25 µg/g, mean of 8.97 µg/g) indicate that the ore‐forming materials originated mainly in the crust. The primary mechanism for mineral deposition in the Lunwei W deposit was a decrease in temperature and the mixing of magmatic and meteoric water. The Lunwei deposit can be classified as a porphyry‐type scheelite deposit and is a product of widespread tungsten mineralization in South China. We summarize the geological characteristics of typical W deposits (the Xingluokeng, Shangfang, and Lunwei deposits) in the Wuyi metallogenic belt and suggest that porphyry and skarn scheelite deposits should be considered the principal exploration targets in this area.  相似文献   

基于物联网多源数据融合的管线监测平台设计应用     

马俊瑞  刘旭  陈晓爽  皮明宇 《北京测绘》2021,35(8):1099-1102

当今城市地下管网安全运行监测数据集成面临涉事业务部门范围广、数据种类繁多、数据采集途径不统一等问题.结合项目实践,通过通信请求响应协议(Http)请求解析、串行通讯协议(Modbus proto-col,Modbus)读取、数据库推送、通信标准接口(OLE for Process Control,OPC)数据采集四种数据对接方式,提出基于物联网多源数据融合的解决思路及实现方法,将数据统一接入存储应用,据此通过快速搭建繁杂的前端脚手架(Vue-cli)设计实现地下管线综合安全运行监测平台.该平台在安庆市地下管网安全运行监测系统项目中得到应用.  相似文献   

基于遥感监测的合肥市城市扩展时空特征及驱动力分析     

夏明宇  刘虎  姜岳  吴博  徐永梅 《测绘与空间地理信息》2021,44(9):140-144,147

城市区域的扩展是城市化的重要表现,准确掌握其形态特征及驱动力机制,对指导城市规划、调整发展布局具有重要意义.本文采用Landsat系列遥感影像为数据源,提取城市建设用地,结合一系列城市扩展评价指标及社会经济统计数据,对近20年合肥市城市扩展时空特征及驱动力因素进行分析.研究表明:2000—2019年间,合肥市城市扩展维持在中高速水平,城市扩展弹性指数偏离合理值,城市扩展重心由中心城区逐渐转移至南部地区.人口增长、经济发展及政策因素是合肥城市扩展的主要驱动力,此外,交通及科教资源也是城市扩展的重要驱动因素.  相似文献   

Dissipation of an electron phase-space hole and its consequence on electron heating     

Mingyu Wu  Quanming Lu  Can Huang  Peiran Wang  Rongsheng Wang  Shui Wang 《Astrophysics and Space Science》2014,352(2):565-570

An electron phase-space hole (electron hole) is considered to be unstable to the transverse instability. In this paper, two-dimensional (2D) electrostatic particle-in-cell (PIC) simulations are used to explore the dissipation process of a one-dimensional (1D) electron hole in a weakly magnetized plasma and its consequence on electron heating, which consists of two stages. In the first stage, the electron hole is still kept as a quasi-1D structure, however, with the excitation of the transverse instability and the generation of the perpendicular electric field, the electrons are scattered and then heated along the perpendicular direction in the electron hole. In the second stage, the quasi-1D electron hole is broken into several 2D electron holes. The temperature of the electrons outside of these 2D electron holes also increase, and at last the velocity distribution of the electrons become almost isotropic in the whole simulation domain. Our results provide a new dissipation mechanism of an electron hole.  相似文献   

沙旺矿区不规则脉状倾斜矿体探采结合与小矿块全面法回采实践     

刘贤玉  周京仁  辛明禹 《山东国土资源》2009,25(10):53-55

不规则脉状倾斜矿体的开采是矿山企业急需解决的技术问题。该文结合矿山采矿法的多年实践,详细地介绍了沙旺矿区小矿体回采的探采结合采矿法和小矿块全面采矿法的结构布置、参数确定、使用情况及具体措施。采场应用结果表明：这2种采矿方法能够安全地、最大限度地提高资源利用率,可带来显著的社会效益和经济效益。  相似文献