共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
影响北京市2次生物质燃烧事件的表征 总被引:1,自引:0,他引:1
采用气相色谱-质谱(GC/MS)法测定2005~2006年北京市31个总悬浮颗粒物(TSP)样品中生物质燃烧分子示踪物——左旋葡聚糖。城区样品左旋葡聚糖的平均含量为334 ng.m-3,变化范围在34.6~1 307ng.m-3之间,与文献报道的台湾云林城区TSP样品的左旋葡聚糖含量水平相差不大,与2003~2004年北京市颗粒物测定结果大体持平,略有降低。通过测定左旋葡聚糖捕捉到影响北京的2次生物质燃烧事件,即2005年10月6日和2006年6月21日邻近省份焚烧玉米秸和麦秸事件。利用气象卫星监测农田焚烧信息,反向风迹图分析这2次事件的源地和传输路径。 相似文献
3.
4.
5.
为研究厦门市大气颗粒物的污染特征及其对酸雨的影响,于2012年12月至2013年7月在厦门市各区分别采集大气中TSP、PM10、PM2.5颗粒物样品,利用离子色谱法分析了其中的水溶性离子成分含量。结果表明,厦门市大气颗粒物中水溶性离子成分分布特征为:Na+和Ca2+离子主要主要分布在TSP、PM10中,而SO42-离子则主要分布在PM10和PM2.5中。说明Na+和Ca2+离子更容易富集在粗颗粒物粒子上,而SO42-离子主要存在于细颗粒物粒子中。厦门市大气颗粒物中对雨水酸度有重要缓冲作用的Ca2+、Mg2+离子浓度处于较低水平,说明厦门市大气颗粒物对雨水酸度缓冲作用较低,这是厦门地区酸雨发生率较高的原因之一。 相似文献
6.
7.
为了提高大气颗粒物数据观测质量,缩短颗粒物浓度异常数据出现时间,文章对β射线法大气颗粒物监测仪监测出的异常数据进行分类研究,并针对常见的观测数据异常现象如颗粒物浓度值突破最大允许值或最小允许值、数据“倒挂”,以及数据不正常波动等,分析对应的故障原因,为总结故障排除方法提供依据。 相似文献
8.
9.
He气氛对大气颗粒物样品外束PIXE分析影响的初步研究 总被引:1,自引:0,他引:1
为改善北师大外束PIXE系统对Al、Si等较轻元素的探测限,在该系统探测器前加装进He装置。采用美国MicroMatter公司的标准样品,在进He量为92.0 SCCM(标况毫升每分钟)的条件下对系统进行刻度,得到GUPIXWIN软件进行定量分析用的16种元素的刻度因子,并同不进He条件下的刻度因子进行比较。在保持实验几何条件不变的情况下,研究He气量对大气颗粒物样品中Si、S、Cl等元素探测限的影响,结果表明:进He量为92.0 SCCM时,可使大气颗粒物样品中Al、Si元素的探测限较不进He气时分别降低80%和47%。 相似文献
10.
大气颗粒物及其组成研究进展(上) 总被引:2,自引:0,他引:2
颗粒物是空气中最重要的污染物之一,由于颗粒物表面的吸附作用,其组分非常复杂,其中含有多种有毒有害的化学成分,对大气环境造成不良影响,并危及人体健康。借助大气颗粒物及其组成成分的测定,通过污染源解析分析其来源及影响因素,控制大气颗粒物的排放,对于保证大气环境质量、改善人们的生存环境具有重大意义。本文对此进行综述。着重介绍大气颗粒物及其组成成分、源解析及测量技术的最新进展。 相似文献
11.
提出了"局部基本元素解析估算 关键点有限元分析"的技术途径.首先从通用性虚拟铣削过程变形量快速分析技术的需求出发,研究了薄壁基本元素的典型类别和相应的变形算法,在此基础上构建了基本元素及变形算法库.为减小快速分析带来的误差,提出对关键点变形量进行有限元和实验校核以获得校正系数的方法.预测变形与实验对比表明提出的技术途径高效可行. 相似文献
12.
首先通过对优化问题的表述,说明稳健优化与传统确定性优化的区别。稳健优化需进行不确定性分析,为此对目标的均值和方差同时进行优化。然后分析和比较了蒙特卡罗法、基于敏感度法、解析法、基于代理模型法等不确定性分析方法的特点,其中着重介绍了基于代理模型的不确定性分析方法。最后讨论了2类求解稳健优化问题的策略:加权法和多目标遗传算法。 相似文献
13.
Selected ion flow tube mass spectrometry (SIFT-MS) is a new analytical technique for the real-time quantification of several trace gases simultaneously in air and breath. It relies on chemical ionization of the trace gas molecules in air/breath samples introduced into helium carrier gas using H(3)O(+), NO(+), and O(2) (+.) precursor ions. Reactions between the precursor ions and trace gas molecules proceed for an accurately defined time, the precursor and product ions being detected and counted by a downstream mass spectrometer, thus effecting quantification. Absolute concentrations of trace gases in single breath exhalation can be determined by SIFT-MS down to ppb levels, obviating sample collection and calibration. Illustrative examples of SIFT-MS studies include (i) analysis of gases from combustion engines, animals and their waste, and food; (ii) breath and urinary headspace studies of metabolites, ethanol metabolism, elevated acetone during ovulation, and exogenous compounds; and (iii) urinary infection and the presence of tumors, the influence of dialysis on breath ammonia, acetone, and isoprene, and acetaldehyde released by cancer cells in vitro. Flowing afterglow mass spectrometry (FA-MS) is briefly described, which allows on-line quantification of deuterium in breath water vapor. 相似文献
14.
15.
A dual‐analysis approach in tribochemistry: application to ZDDP/calcium borate additive interactions
Varlot K. Martin J.M. Grossiord C. Vargiolu R. Vacher B. Inoue K. 《Tribology Letters》1999,6(3-4):181-189
Tribochemical interactions between zinc dithiophosphate (ZDDP) and micellar calcium borate (CB) under boundary lubrication
were investigated by coupling, in the same location of the wear track, both analytical TEM analysis of collected wear fragments
from the tribofilm and XPS surface analysis of the tribofilm directly underneath. This is the so‐called dual‐analysis approach,
which improves the interpretation of tribochemical reactions. The elemental composition inside the wear scars was analysed
by micro‐spot XPS. By depth profiling, the film thickness could also be determined. In particular, the efficiency of the additive
combination could be proven by quantification of iron oxide. The nature of wear particles was investigated in the TEM by using
EELS and EDX simultaneously, with the result that phosphorus, boron and sulphur contributions have been carefully distinguished.
The technique is very powerful for determining the composition of the material through quantification of both EELS and EDX
spectra on the same specimen. The main result, when ZDDP and CB additives are used together, is the formation of a calcium
and zinc borophosphate glass tribofilm. The overall data confirm the general friction‐induced glass model as being a unifying
concept that explains the mechanisms of antiwear additives under boundary lubrication. Moreover, the analytical results strongly
suggest the role of viscous flow of the magma state glass tribofilm above its glass transition temperature to be a main contribution
to the antiwear mechanism under mild wear conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
17.
18.
MINITAB软件在光谱分析中的应用 总被引:2,自引:0,他引:2
MINITAB软件是数据量化分析工具,它与光谱分析原理结合的应用范围是非常大的。MINITAB软件,不仅可以帮助分析人员解决数据量大、统计工作繁锁,而且可以通过数据量化分析结果,说明分析过程中问题产生的主要原因。文章运用MINITAB软件,光谱分析不锈钢中的铬元素测定时,解决了时间短、数据多、数据偏差原因不明确等问题,很好地达到了预期效果。 相似文献
19.
《Mechanical Systems and Signal Processing》2001,15(1):227-242
This paper focuses on quantification of damping non-proportionality present in a discrete vibratory system. The study assumes that the information available is a set of identified system eigenvalues and eigenvectors and that the system parameters such as mass, stiffness, and damping matrices are unknown a priori. This set of modal parameters may be incomplete. The investigation is concentrated on how two existing analytical indices can be utilised when the modal damping matrix is not available. The quantification procedure starts with extraction of normal modes using a known algorithm. It is shown that two matrices, by-products of the normal model extraction, can be used to study damping non-proportionality. The first matrix is a scaled modal damping matrix. The paper shows that the indices developed from the scaled modal damping matrix preserves the properties of the indices based on the analytical modal damping matrix. The second matrix is a complex matrix which is obtained by expanding complex modes into the subspace of real modes. The off-diagonal elements of the complex matrix indicate coupling between modes due to damping non-proportionality. Based on this characteristic, three new indices are proposed. Numerical examples are presented to illustrate the use of the new indices and to compare them with the indices that are described in literature. 相似文献
20.
基于有限元分析理论,利用ANSYS10.0有限元分析软件中的Block Lanczos模块对自行设计的搅拌摩擦焊用测力八角环进行了模态分析.提取了前12阶振动频率和相应振型,分析了各阶振型的特点.总结了测力八角环在结构设计以及运行时应注意的问题,也为后续的动力学分析提供了理论依据. 相似文献