检索结果-南通市图书馆

Complex sources of air-soil-water pollution processes in the Miyun reservoir region

Science china Earth Sciences 2005年第Z2期48卷 230-245页

作者： YANG Dongzhen, XU Xiangde, LIU Xiaoduan, XU Qing, DING Guoan, CHENG Xinghong, CHEN Huailiang, ZHOU Huaigang, WANG Zhenfa, WANG Wenyan key laboratory of Atmospheric Chemistry, Center for Atmosphere Watch and Services, Chinese Academy of meteorological Sciences, CMA, beijing 100081, china key laboratory of meteorological disasters, cams, beijing 100081, china National Center for Geological Testing, beijing 100037, china meteorological Bureau of Henan Province, Zhenzhou 450000, china Shangdianzi Background Atmospheric Pollution Observation Station, Miyun County, beijing 101507, china key laboratory of Atmospheric Chemistry Center for Atmosphere Watch and Services Chinese Academy of Meteorological Sciences CMA Beijing 100081 China key laboratory of meteorological disasters CAMS Beijing 100081 China National Center for Geological Testing Beijing 100037 China meteorological Bureau of Henan Province Zhenzhou 450000 China Shangdianzi Background Atmospheric Pollution Observation Station Miyun County Beijing 101507 China

The comprehensive impact of atmospheric dry deposition and wet deposition and the pollution sources of farmlands, mining areas, and towns along the Baihe River on the water quality of Miyun reservoir is investigated from the angle of the complex sources of air-soil-water pollution processes, in the context of the 1990-2001 precipitation chemical data at Shangdianzi station-a WMO regional background air pollution monitoring station 15 km far from the Miyun reservoir, in conjunction with the atmospheric dry deposition and wet deposition data of the 2002 -2003 beijing City Air Pollution Observation Field Experiment (BECAPEX). Analysis results suggest that the major ions in precipitation in the Miyun reservoir region in this period were SO 42-, NO 3-, NH4+ and Ca2+; wet acid deposition quantity of Miyun reservoir in the summer half year (April to September) was greater than the quantity in the winter half year (October to March), and the annual wet acid deposition in the reservoir exhibited a rising trend with the mean 1038.45 t, the maximum 1766.31 t occurred in 1996, and the minimum 604.02 t in 1994; the long-term averaged pH of atmospheric precipitation in the Miyun reservoir region was 5.20, i.e. weakly acidic, and the interannual variation of pH values displayed a falling trend. pH values of water body at various depths in the Miyun reservoir were all greater than 7.0, but they exhibited vertical and horizontal nonhomogeneity, and at the same region pH decreased vertically with depth; the 2002 and 2003 annual dustfalls in the Miyun reservoir were 13513.08 t and 3577.64 t, respectively, and the spring dustfall was the number one in a year, accounting for the 61.91% and 44.56% of the annual totals of 2002 and 2003, respectively. Because the atmospheric dry deposition and wet depositions contain multiple types heavy metal elements and harmful elements, they to some extent exacerbated the eutrophication, acidification and potential heavy metal pollution of the reservoi

关键词： Miyun reservoir, water quality, Shangdianzi regional background air pollution observation station, atmospheric dry deposition/wet deposition, water system pollution.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Interannual variation of annual precipitation and urban effect on precipitation in the beijing region

引用

Progress in Natural Science:Materials International 2007年第9期17卷 1042-1050页

作者： Yu Shuqiu(State key laboratory on Severe Weather,Chinese Academy of meteorological Sciences,beijing 100081,china) State key laboratory on Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the beijing *** results show that:the annual precipitation in the beijing region possesses the large scale variation character with the linear trend of-1.197/10 yr,which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years;the local annual precipitation anomalies(percent of the normal 1960-2000)show a positive center near the urban area,*** precipitation island(UPI),whose intensity increases with the linear trend of 0.6621%/10 yr,opposite to the interannual trend of large scale precipitation over the beijing region;changes in the UPI are also associated with the intensity of synoptic processes of precipitation,and when the synoptic processes are strong(wet years),the intensity of UPI strengthens,while the synoptic processes are weak(dry years),and the UPI disappears in the beijing region.

关键词： urban precipitation island effect interannual climate variation precipitation beijing atmospheric science

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

An integrative estimation model of summer rainfall-band patterns in china

引用

Progress in Natural Science:Materials International 2007年第3期17卷 280-288页

作者： WEI Fengying (State key laboratory of Severe Weather, Chinese Academy of meteorological Sciences, beijing 100081, china) State key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China

Three variation indices are defined to objectively and quantitatively represent fluctuations of three rainfall-band patterns in summers in china for the period from 1951 to 2005, and the variation features of these indices are analyzed on both of interdecadal and interannual scales. A new method is proposed to establish an integrative estimation model based on the analysis of rainfall-band indices, and the model is applied to air, ocean factors to estimate their roles on variations of three rainfall-band patterns on different time-scales. The tests of estimation effects show that the fluctuations of three rainfall-band patterns are composed of variations on both significant inter-decadal and interannual scales, of which the interannual variation is mainly influenced by the Elnino/Lanina events, the East Asia monsoon and the ridge locations of subtropical high pressures in western pacific, while the interdecadal variation is mainly controlled by the Pacific decadal oscillation and interdecadal oscillations of the Arctic oscillation, ENSO, Nino3 sea surface temperature and summer monsoon. The estimated results from the integrative estimation model of rainfall-band patterns suggest that the way of estimation first according to each time scale of both the interdecadal and interannual scales, then estimating with an integration, which is proposed in this paper, has an obvious improvement on that without separation of time scales.

关键词： rainfall-band pattern interannual variation interdecadal variation integration estimation model.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Interdecadal trend turning of global terrestrial temperature and precipitation during 1951-2002

引用

Progress in Natural Science:Materials International 2008年第11期18卷 1383-1393页

作者： Xiaohui Shi Xiangde Xu State key laboratory of Severe Weather,Chinese Academy of meteorological Sciences,beijing 100081,china State key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China

A grid-by-grid counting of interdecadal trend turning(ITT)of annual mean surface air temperature(SAT)and total precipitation at 67,359 terrestrial grids in the period 1951-2002 is *** analysis of the last ITTs of SAT and total precipitation in the period,in the context of both occurrence time and linear trends after the breakpoint,indicates that a warming trend has become highly significant across most reagent of the world in the late 20th *** terrestrial grids have recorded an ITT of total precipitation in either the 1970s or 1980s,and 45.7% of the terrestrial grids in the study have seen a decreasing trend in total annual precipitation after the break- point,with the remaining 54.3% having experienced an increasing ***,global terrestrial regions have experienced either an increasingly warm and dry climate or an increasingly warm and wet *** analysis of ITT of regional mean SAT and total pre- cipitation in 22 regions shows that the Northern American continent has become increasingly warm and dry after the last interdecadal ***,the African continent has become increasingly warm and wet,with both Europe and most of Asia having the same *** South America and the West of Australia have experienced an opposite trend in climate,becoming increasingly cold and wet.

关键词： Global terrene Surface air temperature Precipitation Interdecadal trend turning

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The least-square method in complex number domain

引用

Progress in Natural Science:Materials International 2006年第3期16卷 307-312页

作者： GU Xiangqian, KANG Hongwen and CAO Hongxing (State key laboratory of Severe Weather, Chinese Academy of meteorological Sciences, beijing 100081, china) State key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China

The classical least-square method was extended from the real number into the complex number domain, which is called the complex least-square method. The mathematical derivation and its applications show that the complex least-square method is different from one that the real number and the imaginary number are separately calculated with the classical least-square, by which the actual least-square estimation cannot be obtained in practice. Applications of this new method to an arbitrarily given series and to the precipitation in rainy season at 160 meteorological stations in china mainland show advantages of this method over other conventional statistical models.

关键词： complex least square Fourier transformation forecast in rainy season.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Theoretical observation of hexaatomic molecules containing pentacoordinate planar carbon

引用

Science china Chemistry 2008年第11期51卷 1030-1035页

作者： LUO Qiong State key laboratory of Explosion Science and Technology, beijing Institute of Technology, beijing 100081, china State key laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing China

The smallest molecules up to date containing a D5h pentacoordinate planar carbon (PPC) atom, CBe5 and CBe54-, are presented by means of ab initio calculations. To gain a better understanding about which electronic factors contribute to their stabilization, natural bond orbital (NBO) analysis and the nucleus independent chemical shifts (NICS) were calculated. The data reported here suggest that D5h CBe5 is σ aromaticity in nature, while in D5h CBe54- π aromaticity is dominating. The classical octet rule is well satisfied in both molecules, and is one of the fundamental reasons to understand the stability of the pentagon structures. The Be5 ring serves as σ donor in D5h CBe5, and π-acceptor in D5h CBe54-. The D5h CBe54- possessing 18 valence electrons with a closed-shell electron configuration is the most plau-sible candidate for experimental detection.

关键词： pentacoordinate planar carbon Be5 ring ab initio

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multiple time scale evaluation of the energy balance during the maize growing season,and a new reason for energy imbalance

引用

Science china Earth Sciences 2009年第1期52卷 108-117页

作者： GUO JianXia1,2,BIAN LinGen3 & DAI YongJiu2 1 meteorological Observation Center of china meteorological Administration,beijing 100081,china 2 State key laboratory of Remote Sensing Science,School of Geography and Remote Sensing Science,beijing Normal University,beijing 100875,china 3 Chinese Academy of meteorological Sciences,beijing 100081,china meteorological Observation Center of china meteorological Administration Beijing China State key laboratory of Remote Sensing Science School of Geography and Remote Sensing Science Beijing Normal University Beijing China Chinese Academy of meteorological Sciences Beijing China

Energy imbalance is a common problem associated with the measurement of surface energy using the eddy covariance *** the evaluation of the energy balance,people usually pay more attention to the statistical result that the effective energy(the sum of sensible and latent heat) is systematically lower than the available energy(the difference of net radiation and ground heat flux).However,little attention has been paid to the existence of the reversed situation when the effective energy is larger than the available energy or their contribution to the overall energy closure *** this paper,based on the analysis of the energy balance on multiple time scales across the maize growth season,we conclude that the non-synchronization of energy components is the main reason for the existence of the reversed *** shifting the phase of the effective energy components half an hour ahead,the rates of energy closure over all time scales are improved and dramatically reduce the number of the half-hourly samples when the energy ratio exceeds 1 or is below *** to the characteristics of the energy distribution and transformation over multiple time scales,latent heat is always the main type of energy cost,and the residual of the energy balance increases with the growth of the maize plant surpassing the sensible heat for seventy *** is suggested that the heat storage and photosynthetic energy play an important role in the energy balance during the growing period of maize.

关键词： maize energy balance multiple time scale energy hysteresis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Jet formation and penetration mechanism of W typed shaped charge

引用

Acta Mechanica Sinica 2009年第1期25卷 107-120页

作者： Cheng Wang Fenglei Huang Jianguo Ning State key laboratory of Explosion Science and Technology,beijing Institute of Technology, 100081 beijing, china State key laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing China

Existing classical shaped charges are well known for their longer jets capable of achieving large hole depth to hole diameter ratios in metallic targets. However, in some situations, there arises demand to obtain 1：1 ratio for hole depth to hole diameter which is beyond normal shaped charges capability. A new variant of shape charge, named W typed shape charge （WSC）, is proposed in this paper, which can meet the demand of 1：1 ratio, and is based on the geometry that can produce annular jets upon proper initiation scheme. In this paper, we present formation and penetration results of WSC based on three different schemes. We also show that not all WSC designs can form annular jets, only annularly initiated WSC, which also fulfils the ＂Internal-External Liners Equal-Impulse＂ criterion, has the capability to form annular jet. The experimental and numerical results show that when the ratio between annular initiation ring diameter and the charge diameter is 0.75, an annular jet is formed, which was also supported by high speed photographs performed in vacuum. 2D numerical simulations are performed with indigenously developed simulation software, where Eulerian approach with multi-material interface tracking algorithm is utilized, to find various mechanisms involved during jet formation process. The calculation results are found in good agreement with the experimental results, indicating that the interface treatment algorithm proposed in this paper can not only deal with large deformation problem, but also depict clearly the variation of materials interface. It is especially suitable for simulation of the process from liner collapse to formation of shaped charge jet.

关键词： WSC Annular jet Interface tracking Numerical simulation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Possible mechanism of the effect of convection over Asian-Australian “land bridge” on the East Asian summer monsoon onset

引用

Science china Earth Sciences 2006年第11期49卷 1223-1232页

作者： HE Jinhai1, WEN Min2, DING Yihui3 & ZHANG Renhe2 1. Jiangsu key laboratory of meteorological Disaster (KLME), Nanjing Institute of Meteorology, Nanjing University of Informa- tion Science and Technology, Nanjing 210044, china 2. State key laboratory of Severe Weather (LaSW), Chinese Academy of meteorological Sciences, beijing 100081, china 3. National Climate Center, Chinese meteorological Administration, beijing 100081, china Jiangsu key laboratory of meteorological Disaster (KLME) Nanjing Institute of Meteorology Nanjing University of Information Science and Technology Nanjing China State key laboratory of Severe Weather (LaSW) Chinese Academy of Meteorological Sciences Beijing China National Climate Center Chinese Meteorological Administration Beijing China

The Asian-Australian “land bridge” is an area with the most vigorous convection in Asian monsoon region in boreal spring, where the onset and march of convection are well associated with the onset of East Asian summer monsoon. The convection occurs over Indo-china Peninsula as early as mid-April, which exerts critical impact on the evolution of monsoon circulation. Before mid-April there are primarily sensible heatings to the atmosphere over Indo-china Peninsula and Indian Peninsula, so the apparent heating ratios over them decrease with height. However, after mid-April it changes into latent heating over Indo-china Peninsula due to the onset of convection, and the apparent heating ratio increases with height in mid- and lower troposphere. The vertical distribution of heating ratio and its differences between Indo-china Peninsula and Indian Peninsula are the key factors leading to the splitting of boreal subtropical high belt over the Bay of Bengal. Such mechanism is strongly supported by the fact that the evolution of the vertical heating ratio gradient above Indo-china Peninsula leads that of 850 hPa vorticity over the Bay of Bengal. Convections over Indo-china Peninsula and its surrounding areas further increase after the splitting. Since then, there is a positive feedback lying among the convective heating, the eastward retreat of the subtropical high and the march of monsoon, which is a possible mechanism of the advance of summer monsoon and convection from Indo-china Peninsula to South china Sea.

关键词： Asian-Australian 'land bridge', tropical convection, Indo-china Peninsula, the splitting of boreal subtropical high belt, East Asian summer monsoon onset.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A thermal-mechanical constitutive model for b-HMX single crystal and cohesive interface under dynamic high pressure loading

引用

Science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 218-226页

作者： WU YanQing & HUANG FengLei State key laboratory of Explosion Science and Technology,beijing Institute of Technology,beijing 100081,china State key laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing China

Due to the significant thermal-mechanical effects during hot spot formation in PBX explosives,a thermodynamic constitutive model has been constructed for HMX anisotropic single crystal subjected to dynamic impact loading. The crystal plasticity model based on dislocation dynamics theory was employed to describe the anisotropic plastic behavior along the preferential slip systems. A modified equation of state (EOS) was introduced into the constitutive equations through the decomposing stress tensor and the nonlinear elasticity for materials was taken into account. The one-dimensional strain impact simulations for HMX single crystal and quasi-bicrystal were performed respectively,in which the cohesive elements were inserted over the interface areas for the latter. The predicted particle velocities for the single crystal sample agreed well with the experimental results in the literature. Furthermore,the effects of crystal orientations,interface,misorientations on localized strain,stress and temperature distributions were predicted and discussed.

关键词： energetic single crystal dynamic high pressure crystal plasticity thermodynamics interfacial model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：