化学质量平衡法在环境空气总悬浮颗粒物源解析中的应用

化学质量平衡法(CMB)是源解析受体模型中最成熟的一种模型,其应用范围越来越广,甚至扩展到水体微环境的污染物源解析领域中。本文系统地介绍了该方法的理论基础,并特别总结了国内CMB法应用的现状。总之,CMB方法是TSP源解析方法中最值得推荐的方法之一。     

长春市大气中PM10本地源和外来源解析对比研究

利用单粒子后向轨迹模型与化学质量平衡模型(CMB)相结合的方法,分别对长春市大气中PM10外来源和本地源贡献率进行源解析研究。CMB 8.2的解析结果中,工业燃煤和以钢铁尘为主的工业尘是外来可吸入颗粒物的最主要来源,非采暖期、采暖期的贡献率分别为13.04%、32.56%和29.75%、14.66%;而机动车尾气和道路尘则是本地可吸入颗粒物的最主要来源,非采暖期、采暖期贡献率分别为39.24%和33.86%。HYSPLIT模型分析,2011年9月30日(非采暖期)对于长春市大气中可吸入颗粒物影响较大的城市为通辽、白城、四平等;2012年3月1日(采暖期)的外来源则来源于兴安盟、白城、松原、吉林以及牡丹江市。     

典型城市大气颗粒物无机组分源解析

采用CMB 8.2受体模型对吉林省4个典型城市大气总悬浮颗粒物(TSP)进行了无机组分源解析研究.共选取了10个采样点,在采暖期和非采暖期采集了环境空气中的总悬浮颗粒物及各类污染源样品156个.研究结果表明,吉林市和白城市对TSP影响较大的是土壤风沙尘;通化市大气主要污染源为道路尘;而四平市的扬尘对TSP的影响较大.研究结果有利于制定大气污染防治规划,对于治理大气环境、改善空气质量具有指导意义.     

用任意次函数拟合需求变化存贮模型的最优解

讨论一类推广的需求率曲线为具有双拐点类型任意次函数的存贮模型,运用间接法给出该模型的解析最优解,其最优解为库存应用中需求率曲线的拟合提供更多的选择方式。     

泰安市城区环境空气可吸入颗粒物源解析研究

本研究主要建立了泰安市可吸入颗粒物(PM10)的源与受体成分谱数据库，通过化学质量平衡(CMB)受体模型进行解析，得出了采暖期和非采暖期各颗粒物污染源对空气可吸入颗粒物污染物的贡献值和分担率，为有针对性的尘污染防治提供科学依据．     

龙岩市大气中PM10的微观形貌特征及组成分析

选择福建省龙岩市环境监测站的大气常规监测点位为采样点, 于2009年9月16日至9月23日进行24 h连续采样, 采用扫描电镜方法分析样品中PM₁₀的微观形貌特征和元素组成, 通过与当地典型污染源颗粒物的微观形貌和特征元素进行对比, 确定其主要污染来源. 研究结果表明: 各类污染源的微观形貌及特征元素均有明显区别,  不同采样点样品中PM₁₀的微观形貌特征及元素组成也有差异, 据此分析得出的大气PM₁₀颗粒物来源与化学质量平衡受体模型(CMB8.2)源解析结果一致.     

南昌市环境空气PM_(2.5)污染现状及其源解析研究方法

根据例行监测数据分析了南昌市环境空气PM2.5污染现状,提出了适用于南昌市PM2.5源解析的主要研究内容,同时根据国内外受体模型的研究进展提出了源解析所用的模型,研究结果可以为下一步南昌市开展PM2.5源解析提供坚实的理论基础。     

基于两种模型的GPS水准拟合软件系统的开发

GPS水准在工程实践中仍然以数学拟合方法为主。简述了移动法曲面模型和克里格(Kriging)统计模型的原理。移动曲面法具有连续性,如果找不到多于6个点参与内插,用程序实现自动选择Kriging方法,把二者结合起来称为综合法。Kriging具有无偏最优的统计性质,两种模型在实践中应用较多,为此开发了基于两种模型的GPS水准拟合软件系统,该软件系统可对拟合结果作精度评价。     

上海道路扬尘粒径两种分析方法的比较

对54个上海城市地表扬尘样品进行激光法与动力学粒径谱仪法的粒径分析结果作了相关比较.拟合结果表明,在缺少空气动力学粒径谱仪的情况下,可以通过回归方程式建立激光粒度仪和动力学粒径谱仪测试结果之间的关系,从而获得研究所需的动力学粒径对应的质量百分比含量.两种仪器测试所得数据的转换结果具有统计学的意义.由于两种方法的原理不同,结果的差异还可为源解析提供进一步分析的线索.     

大平面砂轮磨齿的温升分析

当前平面工件磨削热模型研究较多,但不能应用于齿轮类曲面零件的磨削计算。为此将移动热源法与映像法相结合,在齿轮渐开线圆弧拟合的基础上,建立了大平面砂轮磨齿加工的解析热模型,可用于磨削时齿轮的温升分布计算。同时,在有限元软件ANSYS中对磨齿过程进行了仿真,并将解析热模型和有限元热模型的准稳态温升分布进行比较分析。结果表明,两者的温升分布只在接触区及其与非接触区的交界处存在一定的误差,总体结果吻合较好。其解析热模型可用于齿轮类曲面工件加工时的温升分析。     

基于覆盖的神经网络集成在语音识别中的应用

神经网络集成通过训练多个神经网络并将各网络的结论进行合成,从而得到最终结果.集成可以显著的提高学习系统的泛化能力.讨论了基于覆盖思想而设计的神经网络集成方法,并将其应用于汉语孤立数码语音识别系统中,通过在集成过程中加入基于覆盖思想的控制算法降低系统的泛化误差,从而使系统的识别效果有了进一步的提高.     

Measurement of polarization with the Degree Angular Scale Interferometer

Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was approximately 400,000 years old. The three most fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station.     

自动跟踪型汽车前照灯检测仪研究与实现

自动跟踪型汽车前照灯检测仪是集光、机、电技术于一体的专用仪器设备.可自动跟踪光轴,利用图像传感器对灯光图像进行采集,并利用数字图像处理技术对灯光图像进行处理,从而得到多个测量参数,是建立在多学科基础上的综合技术.试图从工程应用的角度出发,利用先进的嵌入式系统,研究如何快速准确地自动跟踪光轴、对灯光图像进行采集、对汽车前照灯的远近光进行自动检测,以及提高精度和抗干扰技术.     

VSD模型在评估煤层气储量中的应用

煤层气是非常规天然气的一种,是国内天然气产量的重要组成部分.经过多年勘探开发,沁水盆地南部和鄂尔多斯盆地东部已经形成多了商业开发区块,获得了大量精确的储量数据;但中国煤层气分布广泛,勘探程度不一,储量认知程度严重不均衡.通过勘探程度较高的储量数据来预测所有区块的储量.为了正确预测和评价国内煤层气资源量.评价模型中选用VSD(variable shape distribution)模型,与常规分形分布模型相比,比如对数正态分布和帕累托分布,具有精度高,拟合灵活准确的特点.在成熟度高的气田储量基础上,拟合出VS模型所需的参数,然后利用这套参数预测评价出国内81个煤层气区块的资源量,为煤层气的勘探部署和经济分析提供参考数据.     

Detection of polarization in the cosmic microwave background using DASI. Degree Angular Scale Interferometer

The past several years have seen the emergence of a standard cosmological model, in which small temperature differences in the cosmic microwave background (CMB) radiation on angular scales of the order of a degree are understood to arise from acoustic oscillations in the hot plasma of the early Universe, arising from primordial density fluctuations. Within the context of this model, recent measurements of the temperature fluctuations have led to profound conclusions about the origin, evolution and composition of the Universe. Using the measured temperature fluctuations, the theoretical framework predicts the level of polarization of the CMB with essentially no free parameters. Therefore, a measurement of the polarization is a critical test of the theory and thus of the validity of the cosmological parameters derived from the CMB measurements. Here we report the detection of polarization of the CMB with the Degree Angular Scale Interferometer (DASI). The polarization is deteced with high confidence, and its level and spatial distribution are in excellent agreement with the predictions of the standard theory.     

Thermal and electrical conductivity of iron at Earth's core conditions

The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core.     

Missing completely of the CMB quadrupole in WMAP data

In cosmic microwave background (CMB) experiments, foreground-cleaned temperature maps are still contaminated by the residual dipole due to uncertainties of the Doppler dipole direction and microwave radiometer sidelobe. To obtain reliable CMB maps, such contamination has to be carefully removed from observed data. We have previously built a software package for map-making, residual dipole-contamination removal, and power spectrum estimation from the Wilkinson Microwave Anisotropy Probe (WMAP) raw data. This software has now been significantly improved. With the improved software, we obtain a negative result of CMB quadrupole detection with the WMAP raw data, which is 3.2±3.5 K2 from the seven-year WMAP (WMAP7) data. This result is evidently incompatible with ～1000 K2 expected from the standard cosmological model ΛCDM. The completely missing of CMB quadrupole poses a serious challenge to the standard model and sets a strong constraint on possible models of cosmology. Due to the importance of this result for understanding the origin and early evolution of our universe, the software codes we used are opened for public checking.     

地磁场能量在地球内部的三维分布及其长期变化

 利用Bloxham&;Jackson地磁场模型(BJ)和国际地磁参考场模型(IGRF)资料,计算并分析了1690年以来地磁总能量、北向、东向和垂直向分量的能量从CMB到地表的分布和时间变化.结果表明,地磁场总能量以及北向和垂直向分量的能量在地表和地球内部的变化一致,1690年以来减小,东向分量的能量变化以波动形式增大,偶极子磁场能量持续减小.非偶极子磁场的能量1690~1770年减小,1770年以后增大.磁能密度在CMB附近增大较快,地表的磁能密度只有CMB的1.6%.从地表向下至CMB,偶极子和非偶极子的磁能密度的变化相反,偶极子减小,非偶极子增大.     

Pseudo-dipole signal removal from WMAP data

We have discovered in our previous work that different observational systematics, e.g. errors from antenna pointing directions or an asynchronism between the attitude and science data may generate a pseudo-dipole signal in the full-sky maps of the cosmic microwave background (CMB) anisotropy that have been published by the Wilkinson Microwave Anisotropy Probe (WMAP) team. We have found that the antenna sidelobe response to the Doppler signal produces a similar effect. In this work, independent from the sources, we have uniformly modeled the pseudo-dipole signal and have removed it from the published WMAP7 CMB maps by model fitting. The result demonstrates that the released WMAP CMB quadrupole is almost completely artificial.     

玉溪市中心城区环境空气中TSP的源解析

应用受体模式的化学质量平衡法对玉溪市中心城区大气颗粒物的来源进行解析。分别采集玉溪市监测站、大营街和东风水库3个监测点大气中总悬浮颗粒物(TSP)样品，同时采集了土壤尘、煤烟尘、钢铁尘、交通尘和建材尘等5种源样品。采用电感耦合等离子体光谱仪分别测定受体和源样品中11种元素的质量比。建立玉溪市源解析的化学质量平衡受体模型，模型的计算得出了这5种污染源对TSP的贡献率分别是土壤尘为40．75％、建材尘为31．06％、煤烟尘为18．37％、钢铁尘为8．09％和交通尘为1.73％。