The numerical simulation and inversion fitting of radon concentration distribution in homogeneous overburden above active fault zones

Based on the convection and diffusion mechanisms of radon migration, in this paper we deduce the two-dimensional differential equation for radon transportation in the overburden above active fault zones with an unlimited extension along the strike. Making use of the finite difference method, the radon concentration distribution in the overburden above active faults is calculated and modeled. The active fault zone parameters, such as the depth and the width of the fault zone, and the value of radon concentration, can be inverted from the measured radon concentration curve. These realize quantitative interpretation for radon concentration anomalies. The inversion results are in good agreement with the actual fault zone parameters.

Experimental Research on Quantitative Inversion Models of Suspended Sediment Concentration Using Remote Sensing Technology

Research on quantitative models of suspended sediment concentration （SSC） using remote sensing technology is very important to understand the scouting and siltation variation in harbors and water channels. Based onlaboratory study of the relationship between different suspended sediment concentrations and reflectance spectra measured synchronously, quantitative inversion models of SSC based on single factor, band ratio and sediment parameter were developed, which provides an effective method to retrieve the SSC from satellite images. Results show that the bl （430-500nm） and b3 （670-735nm） are the optimal wavelengths for the estimation of lower SSC and the b4 （780-835nm） is the optimal wavelength to estimate the higher SSC. Furthermore the band ratio B2/B3 can be used to simulate the variation of lower SSC better and the B4/B1 to estimate the higher SSC accurately. Also the inversion models developed by sediment parameters of higher and lower SSCs can get a relatively higher accuracy than the single factor and band ratio models.

Study on the Concentration Inversion of NO &NO2 Gas from the Vehicle Exhaust Based on Weighted PLS

It becomes a key technology to measure the concentration of the vehicle exhaust components with the absorption spectra. But because of the overlap of gas absorption bands, how to separate the absorption information of each component gas from the mixed absorption spectra has become the key point to restrict the precision of the optical detection method. In this paper, the ex-perimental platform for the absorption spectrum of vehicle exhaust components has been established. Based on the ultraviolet absorption spectra measured with the platform of exhaust gas NO & NO2, the concentration regression model for the two components has been established with weighted partial least squares regression (WPLS). Finally the each spectral characteristic information of NO & NO2 gas has been separated and the concentration of each corresponding component has been reversed successfully.

The forward and inverse problem of cardiac magnetic fields based on concentric ellipsoid torso-heart model

This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a current dipole and volume currents. Then by using the simulated magnetic fields based on torso-heart model as input, the cardiac current sources--an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries is compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.

Determination of elastic moduli of composite medium containing bimaterial matrix and non-uniform inclusion concentrations

Reservoir porous rocks usually consist of more than two types of matrix materials, forming a randomly heterogeneous material. The determination of the bulk modulus of such a medium is critical to the elastic wave dispersion and attenuation. The elastic moduli for a simple matrix-inclusion model are theoretically analyzed. Most of the efforts assume a uniform inclusion concentration throughout the whole single-material matrix. However, the assumption is too strict in real-world rocks. A model is developed to estimate the moduli of a heterogeneous bimaterial skeleton, i.e., the host matrix and the patchy matrix. The elastic moduli, density, and permeability of the patchy matrix differ from those of the surrounding host matrix material. Both the matrices contain dispersed particle inclusions with different concentrations. By setting the elastic constant and density of the particles to be zero, a double-porosity medium is obtained. The bulk moduli for the whole system are derived with a multi-level effective modulus method based on Hashin＇s work. The proposed model improves the elastic modulus calculation of reservoir rocks, and is used to predict the kerogen content based on the wave velocity measured in laboratory. The results show pretty good consistency between the inversed total organic carbon and the measured total organic carbon for two sets of rock samples.

Inversion of oceanic chlorophyll concentrations by neural networks

Neural networks (NNs) for the inversion of chlorophyll concentrations from remote sensing reflectance measurements were designed and trained on a subset of the SeaBAM data set. The remaining SeaBAM data set was then applied to evaluating the performance of NNs and compared with those of the SeaBAM empirical algorithms. NNs achieved better inversion accuracy than the empirical algorithms in most of chlorophyll concentration range, especially in the intermediate and high chlorophyll regions and Case II waters. Systematic overestimation existed in the very low chlorophyll (【0.031 mg/m3) region, and little improvement was obtained by changing the size of the training data set.

基于图像取反的同心圆环半径和圆心提取方法

为了解决非定域干涉同心圆环图像的圆心和半径的精确提取问题,提出了一种基于图像取反的暗亮环兼顾的算法,以点光源非定域干涉同心圆环为对象,在平滑降噪预处理基础上,利用霍夫圆变换获得参考圆心,以参考圆心为基础分别在其x方向和y方向上[-50,50]像素范围内每隔5 pixel取一条强度轮廓线,每一条强度轮廓线取反后,分别实现暗环和亮环峰位坐标的精确识别,再利用圆回归拟合得到系列圆心和半径,通过系列圆心和半径的平均运算实现图像最终圆心和半径的精确提取。结果表明,靠近中心的3个亮环和3个暗环各自的圆心坐标非常接近,相对于总平均值的最大偏差为-3.7 pixel,即相对于总平均值的最大相对偏差为-0.15%,重复性很好;相邻两个圆环半径平方比值相对于实际比值的误差在-4.18%~0.36%之间变化,验证了算法的可行性。该研究对实现自动化检测、提高测量精度是有帮助的。

基于自适应红外多波段联合光谱分析的高精度气体浓度反演研究

本文提出一种自适应多波段联合浓度反演算法,结合透过率稳定区间与谱宽阈值自适应选择待测气体的有效波段;采用非线性最小二乘拟合方法对各有效波段进行浓度反演及残差分析,获得各有效波段的浓度反演结果及其权重,通过加权平均实现待测气体浓度的精确定量分析。设计并进行实验验证,结果表明,自适应多波段联合浓度反演算法的稳定系数达到了0.9976,与传统的单波段及多波段浓度反演算法相比,该反演结果的均方根误差分别降低了64.44%和41.52%,平均相对误差分别降低了65.97%和46.72%,平均绝对误差分别降低了66.32%和47.74%,反演精度与稳定性得到了明显提升。

基于GF-1卫星遥感反演排水河沟水体溶存N_(2)O浓度模型对比研究

[目的]探究利用GF-1卫星数据反演水体溶存氧化亚氮(N_(2)O)浓度的可行性,为实现低成本、高效率的水质实时监测提供有效途径。[方法]以宁夏青铜峡灌区第1和第5排水河沟为研究对象,选取与排水河沟水体溶存N_(2)O浓度相关性高的GF-1卫星影像波段反射率和水质参数作为自变量,通过最优子集筛选法确定最优自变量组合,分别构建了多元线性回归、BP神经网络和支持向量机模型,对水体溶存N_(2)O浓度进行预测对比。[结果]水温(T)、溶解性有机碳(DOC)等是影响水体溶存N_(2)O浓度的主要因素,同时近红外(NIR)等卫星波段与水体溶存N_(2)O浓度变化趋势显著相关。当自变量包括T,NIR等7个因素时,模型预测效果最佳。在3种模型中,BP神经网络模型验证结果R^(2)为0.64,具有最高预测精度。[结论]GF-1卫星数据以及水质参数与水体溶存N_(2)O浓度存在复杂的相关性关系,且BP神经网络能够实现利用GF-1卫星数据较高精度地反演水体溶存N_(2)O浓度。

非制冷快照式红外视频光谱成像仪及其数据处理

随着现代社会的工业化进程和快速发展,工业生产中的危险化学气体泄漏严重危及人身财产安全。如何有效检测污染气体的存在并获取气体的浓度和分布等信息,成为气体泄漏检测的重要课题。非制冷快照式红外视频光谱成像仪(Uncooled Snapshot Infrared Video Spectrometer,USIVS)是一种理想的硬件方案,能够直接从图像中感知危险化学气体的存在并获取危险化学气体的位置,为紧急处置提供有力支持。但是,商业化的轻量级被动式红外光谱成像仪的灵敏度和光谱分辨率相对受限,已有的气体浓度反演方法难以准确检测污染气体的存在。本文介绍了一种基于非制冷快照式红外视频光谱成像仪及其适用的数据处理技术流程。利用气体浓度反演方法对不同温度和光程长度下的气体进行了模拟实验,并得到了较为准确的反演结果,平均误差分别为2.88%和0.61%。在实验室和室外场景下进行了气体浓度反演方法的测量实验,结果表明该算法具有较好的稳定性,平均误差分别为6.18%和7.47%。通过USIVS与数据处理技术流程的有效结合,能够快速准确地检测污染气体的存在并给出图像中每个像素的气体浓度,实现气云浓度反演的效果,为后续该类技术的商业化及实用化提供了参考。

利用Sentinel-2卫星影像反演骆马湖叶绿素a浓度

本文利用2023年6月15日采集的骆马湖水质参数、光谱数据和同期Sentinel-2影像数据,构建了基于数学统计和机器学习方法的水质反演模型,并对骆马湖叶绿素a(Chl-a)浓度进行了定量反演。通过对比分析,选定了性能最优的模型分析骆马湖Chl-a浓度状况。研究发现,Chl-a浓度与Sentinel-2影像B5和B9波段表现出较高的相关性,且经波段组合处理后,相关性进一步提升。在Chl-a反演模型中,FA-SVR模型相较于传统数学统计回归模型及其他机器学习模型(FA-RF、FA-XGBoost)表现出最高的精度(R^(2)=0.86,RMSE=2.77,MAE=2.10)。反演结果揭示,骆马湖东北部近岸区域的Chl-a浓度较高,这可能与北部水域存在鱼塘养殖、水体富营养高有关。本文突显了机器学习技术在提升水质遥感反演精度方面的重要应用价值,为湖泊水质监控和管理提供了重要的技术支撑。

基于ISFO-KELM的SF_(6)电气设备故障组分CO_(2)浓度反演模型

SF_(6)电气设备内部的分解组分可以通过可调谐吸收光谱技术进行检测,其中CO_(2)浓度反映了设备内部的绝缘缺陷情况。因此,通过准确测量CO_(2)浓度可以及时发现设备潜在的绝缘故障。为克服传统最小二乘法浓度反演模型稳定性较差的问题,文中基于改进的旗鱼优化算法(Improved Sailed Fish Optimizer,ISFO)与核极限学习机(Kernel Based Extreme Learning Machine,KELM)建立了ISFO-KELM气体浓度反演模型。利用多策略初始化方法、Levy随机步长、柯西变异和自适应t分布变异等技术提升了旗鱼优化算法寻优能力和跳出局部最优解能力。实验结果表明,该模型具有高精度和鲁棒性,并且在稳定性和泛化能力方面优于最小二乘法、极限学习机、反向传播(Back Propagation,BP)神经网络等传统方法,对评估SF_(6)电气设备运行状态具有重要意义。

大气气溶胶浓度和粒度特征研究进展

空气质量关系人们的生活质量,气溶胶由于能直接影响空气质量,而受到越来越多的关注。通过对表征气溶胶性质的浓度和粒度两个重要特征量的研究进展进行梳理总结,以推动其在生态环境领域的基础研究和应用推广。分别从大气气溶胶浓度和粒度的数据获得方法、时空分布、影响因素等方面进行了系统的阐述分析,并对研究方向进行了展望。随着科学技术的进步,气溶胶地面监测方法将进一步优化,遥感监测将得到进一步的扩大应用,尤其从数据源和反演算法两个方面进一步提高反演的精度,而且多源大数据的应用也将是推进气溶胶研究的重要方向。

基于实测光谱的白洋淀叶绿素a浓度反演

内陆水体叶绿素a浓度决定其浮游生物含量,是衡量水体富营养化程度的主要指标,更是影响水体表观反射率光谱的重要因素之一。三波段生物光学模型能有效避免二类水体中悬浮物与化学物质等因素的影响,准确估算叶绿素a浓度。以雄安新区白洋淀为研究区域,利用实测水体光谱及水体叶绿素a浓度,分析水体光谱特征,利用穷举法确定三波段因子位置,建立三波段反演模型及精度验证,最后对结果进行分析评价。结果表明,在λ_(1)=673 nm,λ_(2)=729 nm,λ_(3)=782 nm处,三波段模型反演因子[R_(rs)^(-1)(673)-R_(rs)^(-1)(729)]R_(rs)(782)与叶绿素a浓度的相关系数最高为0.82。该模型的决定系数、均方根误差、平均绝对误差、平均相对误差分别为0.67、3.61μg/L、2.86μg/L、26.06%,表明对于悬浮物以及化学物质较高的水体,三波段模型相较于波段比值与单波段模型具有很好的反演精度。该研究为白洋淀叶绿素a浓度反演提供了一定的理论依据和技术支持,有助于白洋淀水质持续监测,也为后续使用三波段模型反演二类水体叶绿素a浓度提供了算法支持。

胶东招远-平度断裂地球物理异常特征及其控矿条件研究

招远-平度断裂是胶东金矿集区三条超大型控矿断裂(三山岛、焦家及招远-平度断裂)之一。受地表第四系覆盖影响,金矿体空间赋存位置与主断裂及其次级断裂地表出露位置的耦合关系尚存问题。通过开展精细化处理区域重力和航空磁测数据,如空间域不同高度延拓(100 m、200 m和500 m)及垂向一阶导数等方法,发现招远-平度断裂地表出露位置与深部地球物理梯度带存在位移差,且位移差向断裂倾向方向南东侧移动趋势愈发明显,进一步证明招远-平度断裂深部倾向南东,倾角由浅至深逐渐变缓,局部变化剧烈的地质推论。同时,开展地表高精度1/10000比例尺的重力结果显示,重力异常曲线自西向东整体呈快速上升趋势,局部存在凹陷区,表明花岗质碎裂岩及绢英岩化花岗质碎裂岩密度(2.63 g/cm^(3))介于玲珑二长花岗岩(2.57 g/cm^(3))和古元古界(2.82 g/cm^(3))之间,含矿层位与围岩存在较大密度差,金矿体主要赋存于花岗质碎裂岩及绢英岩化花岗质碎裂岩层位的倾角由陡变缓或由缓变陡的转折部位,可分别发现石英脉型金矿和蚀变岩型金矿。

基于动力定位技术的火电厂碳排放实时监测系统

为提升火电厂碳排放监测效果,设计一种基于动力定位技术的火电厂碳排放实时监测系统。首先设计火电厂碳排放在线监测装置,在气体浓度反演模块中,应用最小二乘法拟合法与多元函数求极值法实施测量气体的浓度反演。在烟气定位模块中实施火电厂烟气定位与测量。利用设计系统对某火电厂实施碳排放实时监测,测试结果表明,设计系统能够实现多处测点的火电厂碳排放实时监测,监测结果与实际情况相符;测点处采样探头上落下的烟尘量非常轻微,最低仅为0.005 mm,能够实现烟气定位与烟气差压测量,实用性能良好。

Estimation of solid concentration in solid-liquid two-phase flow in horizontal pipeline using inverse-problem approach

In this study,an inverse-problem method was applied to estimate the solid concentration in a solid-liquid two-phase flow.An algebraic slip mixture model was introduced to solve the forward problem of solid-liquid convective heat transfer.The time-average conservation equations of mass,momentum,energy,as well as the volume fraction equation were computed in a computational fluid dynamics(CFD)simulation.The solid concentration in the CFD model was controlled using an external program that included the inversion iteration,and an optimal estimation was performed via experimental measurements.Experiments using a fly-ash-water mixture and sand-water mixture with different solid concentrations in a horizontal pipeline were conducted to verify the accuracy of the inverse-problem method.The estimated results were rectified using a method based on the relationship between the estimated results and estimation error;consequently,the accuracy of the corrected inversion results improved significantly.After a verification through experiments,the inverse-problem method was concluded to be feasible for predicting the solid concentration,as the estimation error of the corrected results was within 7%for all experimental samples for a solid concentration of less than 50%.The inverse-problem method is expected to provide accurate predictions of the solid concentration in solid-liquid two-phase flow systems.

基于Sentinel-2卫星数据的城市湖泊湿地叶绿素A及总悬浮物浓度定量监测分析——以长沙市松雅湖为例

将湖南省长沙市松雅湖生态湿地湖泊作为研究区,以2016年12月9日和2020年11月8日两期Sentinel-2卫星MSI影像为基础数据源,基于二类水体区域性近岸海域水色算法(C2RCC),对监测区的叶绿素A浓度及总悬浮物浓度进行反演。监测结果表明,秋冬季节,松雅湖水生态修复区的叶绿素A浓度和总悬浮物浓度平均值与非修复区相比,呈现整体偏低的趋势。随着时间推移,松雅湖三个区域的整体叶绿素A浓度和悬浮物浓度均有明显降低。研究结果表明,此方法可为快速高效开展生态湿地湖泊水体的生态状况评价提供基础数据支撑。

基于高分遥感影像的总磷浓度反演研究

以定量遥感反演水质参数为目的,以天津市海河下游段为研究区,利用总磷实测水质数据和同期GF-2PMS 2遥感影像数据,建立两者的偏最小二乘回归模型、单隐含层神经网络模型、双隐含层神经网络模型及粒子群算法优化的双隐含层神经网络模型(DP-BPNN模型)。通过决定系数、平均绝对误差、均方根误差进行精度检验,选出研究区水体适用的总磷浓度的反演模型。结果表明:与偏最小二乘模型精度对比,所建总磷反演模型精度提高了48%。

北京秋冬季近地层PM_(2.5)质量浓度垂直分布特征

选取秋冬两季各14d对北京地区近地层ρ(PM2 5)垂直分布进行监测,获得ρ(PM2.5)垂直廓线;结合同步测得的气象数据,就气象因素对垂直分布的影响进行了分析;最终拟合了ρ(PM2.5)垂直廓线方程。研究表明:秋冬两季ρ(PM2 5)的垂直分布随高度增加而呈对数递减的规律;风速随高度的变化遵循对数规律;发生逆温时,大气层结稳定,垂直方向上的湍流受到抑制,风速与PM2 5逐时质量浓度在垂直方向的分布呈较好的线性关系,ρ(PM2 5)随高度改变呈显著的对数相关关系;而在非逆温的情况下,PM2 5逐时质量浓度垂直分布与风速线性相关的概率较小,质量浓度的垂直分布与高度的对数关系不显著。