Bayesian inversion

  • 文章类型: Journal Article
    明确石油烃在土壤中的赋存状态和形态特征,有助于全面了解石油烃在土壤/沉积物中的迁移和转化规律。此外,通过建立每个发生状态的动态转换过程,可以更准确地评估与土壤/沉积物中PHs相关的生态影响和环境风险。通过基于Tenax-TA的新型顺序提取方法,进行了吸附实验和封闭静态孵育实验,以探索外源细菌自然衰减(NA)和生物强化(BA)两种修复方案下老化污染土壤中PHs的降解和分数分布。羟丙基-β-环糊精和鼠李糖脂(HPCD/RL),加速溶剂萃取器(ASE)装置和碱水解萃取。吸附实验结果表明,生物强化可以促进PHs在吸附阶段的解吸,土水分配系数Kd由0.153L/g降至0.092L/g。孵化实验结果表明,与自然衰减相比,生物强化可以提高老化土壤中PHs的利用率,促进不可提取烃的产生。在实验的第90天,自然衰减和生物强化实验组的弱吸附烃浓度分别下降了46.44%和87.07%,分别,强吸附烃和不可萃取烃的浓度增加了77.93%,182.14%,80.91%,和501.19%,分别,比较它们的初始值。我们开发了一个新的动力学模型,并通过参数扫描函数和基于COMSOLMultiphysics®有限元软件中的贝叶斯方法结合实验数据的马尔可夫链蒙特卡罗(MCMC)方法反演了模型的动力学参数。实验插值数据与模型预测数据之间存在良好的线性关系。弱吸附烃浓度的R2为0.9953至0.9974,强吸附烃的R2为0.9063至0.9756,不可萃取烃的R2为0.9931至0.9982。这些极高的相关系数证明了使用贝叶斯反演方法计算的参数的高精度。
    Clarifying the occurrence and morphological characteristics of petroleum hydrocarbons (PHs) in soil can facilitate a comprehensive understanding of their migration and transformation patterns in soil/sediment. Additionally, by establishing the dynamic transformation process of each occurrence state, the ecological impact and environmental risk associated with PHs in soil/sediment can be assessed more precisely. The adsorption experiments and closed static incubation experiments was carried out to explore the PHs degradation and fraction distribution in aged contaminated soil under two remediation scenarios of natural attenuation (NA) and bioaugmentation (BA) by exogenous bacteria through a new sequential extraction method based on Tenax-TA, Hydroxypropyl-β-cyclodextrin and Rhamnolipid (HPCD/RL), accelerated solvent extractor (ASE) unit and alkaline hydrolysis extraction. The adsorption experiment results illustrated that bioaugmentation could promote the desorption of PHs in the adsorption phase, and the soil-water partition coefficient Kd decreased from 0.153 L/g to 0.092 L/g. The incubation experiment results showed that compared with natural attenuation, bioaugmentation could improve the utilization of PHs in aged soil and promote the generation of non-extractable hydrocarbons. On the 90th day of the experiment, the concentrations of weakly adsorbed hydrocarbons in the natural attenuation and bioaugmentation experimental groups decreased by 46.44% and 87.07%, respectively, while the concentrations of strongly adsorbed hydrocarbons and non-extractable hydrocarbons increased by 77.93%, 182.14%, and 80.91%, and 501.19%, respectively, compared their initial values. We developed a novel dynamic model and inverted the kinetic parameters of the model by the parameter scanning function and the Markov Chain Monte Carlo (MCMC) method based on the Bayesian approach in COMSOL Multiphysics® finite element software combined with experimental data. There was a good linear relationship between experimental interpolation data and model prediction data. The R2 for the concentrations of weakly adsorbed hydrocarbons ranged from 0.9953 to 0.9974, for strongly adsorbed hydrocarbons from 0.9063 to 0.9756, and for non-extractable hydrocarbons from 0.9931 to 0.9982. These extremely high correlation coefficients demonstrate the high accuracy of the parameters calculated using the Bayesian inversion method.
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  • 文章类型: Journal Article
    相机校准对于许多机器视觉应用是必要的。校准方法基于旨在找到相机参数的最佳估计的线性或非线性优化技术。在计算机视觉中,用于校准固有相机参数和镜头畸变(内部定向)的最常用方法之一是张法。此外,相机参数的不确定性通常是通过假设它们的可变性可以由棋盘的不同姿势的图像解释来估计的。然而,最佳参数值及其相关不确定性的可靠程度尚未得到验证。相机校准期间内在和外在参数的不准确估计可能在后处理中引入额外的偏差。这就是为什么我们提出了一种新颖的基于贝叶斯推理的方法,使我们能够评估张的相机校准程序的确定性程度。为此,假定优先概率是张估计的概率,并通过贝叶斯反演对固有参数进行重新校准。发现内在参数的不确定性与张法估计的不确定性不同。然而,不准确的主要原因是计算外部参数的过程。新的基于贝叶斯推理的方法中使用的程序显着提高了图像点预测的可靠性,因为它优化了外部参数。
    Camera calibration is necessary for many machine vision applications. The calibration methods are based on linear or non-linear optimization techniques that aim to find the best estimate of the camera parameters. One of the most commonly used methods in computer vision for the calibration of intrinsic camera parameters and lens distortion (interior orientation) is Zhang\'s method. Additionally, the uncertainty of the camera parameters is normally estimated by assuming that their variability can be explained by the images of the different poses of a checkerboard. However, the degree of reliability for both the best parameter values and their associated uncertainties has not yet been verified. Inaccurate estimates of intrinsic and extrinsic parameters during camera calibration may introduce additional biases in post-processing. This is why we propose a novel Bayesian inference-based approach that has allowed us to evaluate the degree of certainty of Zhang\'s camera calibration procedure. For this purpose, the a prioriprobability was assumed to be the one estimated by Zhang, and the intrinsic parameters were recalibrated by Bayesian inversion. The uncertainty of the intrinsic parameters was found to differ from the ones estimated with Zhang\'s method. However, the major source of inaccuracy is caused by the procedure for calculating the extrinsic parameters. The procedure used in the novel Bayesian inference-based approach significantly improves the reliability of the predictions of the image points, as it optimizes the extrinsic parameters.
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  • 文章类型: Journal Article
    在过去的几年里,短命不饱和卤代烃已作为长寿命卤化温室气体和臭氧消耗物质的环保替代品上市。用于各种应用的不饱和卤化碳的相加入,如制冷和发泡,可以通过它们在大气中的出现和增加来跟踪。我们介绍了氢氟烯烃(HFO)HFO-1336mzz(Z)((Z)-1,1,1,4,4,4-六氟-2-丁烯,顺式-CF3CH=CHCF3),一种新使用的不饱和氢氟碳化合物。自2018年以来,HFO-1336mzz(Z)在三个瑞士和一个荷兰地点进行的为期几个月的活动中,在超过90%的所有测量中都被检测到。自2019年以来,在瑞士高海拔少女站连续运行的所有测量数据中,有30%被发现。在污染事件期间,观察到高达10ppt的摩尔分数。根据我们的测量,瑞士和荷兰的排放量估计为2-7Mgyr-1(2019-2021)和30Mgyr-1(2022),分别。建模的空间排放分布仅部分符合这两个国家的人口密度。监测大气中新的不饱和卤代烃的存在至关重要,因为它们的降解产物的长期影响仍存在争议。此外,HFOs的生产涉及气候活性物质,可能泄漏到大气中──在HFO-1336mzz(Z)的情况下,例如,消耗臭氧层的CFC-113a(CF3CCl3)。
    For the past few years, short-lived unsaturated halocarbons have been marketed as environmentally friendly replacements for long-lived halogenated greenhouse gases and ozone-depleting substances. The phase-in of unsaturated halocarbons for various applications, such as refrigeration and foam blowing, can be tracked by their emergence and increase in the atmosphere. We present the first atmospheric measurements of the hydrofluoroolefin (HFO) HFO-1336mzz(Z) ((Z)-1,1,1,4,4,4-hexafluoro-2-butene, cis-CF3CH═CHCF3), a newly used unsaturated hydrofluorocarbon. HFO-1336mzz(Z) has been detected in >90% of all measurements since 2018 during multi-month campaigns at three Swiss and one Dutch location. Since 2019, it is found in ∼30% of all measurements that run continuously at the Swiss high-altitude Jungfraujoch station. During pollution events, mole fractions of up to ∼10 ppt were observed. Based on our measurements, Swiss and Dutch emissions were estimated at 2-7 Mg yr-1 (2019-2021) and 30 Mg yr-1 (2022), respectively. Modeled spatial emission distributions only partly conform to population density in both countries. Monitoring the presence of new unsaturated halocarbons in the atmosphere is crucial since long-term effects of their degradation products are still debated. Furthermore, the production of HFOs involves climate-active substances, which may leak to the atmosphere─in the case of HFO-1336mzz(Z), for example, the ozone-depleting CFC-113a (CF3CCl3).
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  • 文章类型: Journal Article
    Magnetic resonance elastography (MRE) is an MRI-based diagnostic method for measuring mechanical properties of biological tissues. MRE measurements are processed by an inversion algorithm to produce a map of the biomechanical properties. In this paper a new and powerful method (ensemble Kalman inversion with level sets (EKI)) of MRE inversion is proposed and tested. The method has critical advantages: material property variation at disease boundaries can be accurately identified, and uncertainty of the reconstructed material properties can be evaluated by consequence of the probabilistic nature of the method. EKI is tested in 2D and 3D experiments with synthetic MRE data of the human kidney. It is demonstrated that the proposed inversion method is accurate and fast.
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  • 文章类型: Journal Article
    国家规模甲烷(CH4)排放的准确变化对于了解区域CH4预算至关重要,对于调整国家气候缓解政策以减少这种具有高变暖潜力的温室气体在大气中的积累至关重要。根据库存,目前居住在亚洲人口30%的印度被评估为CH4来源地区。迄今为止,在印度多个地点使用直接测量边界层CH4浓度来估算区域CH4排放量的报告并不多。这里,从印度半岛上三个遥远的站点进行的2年(2017-2018年)的原位CH4观测值与使用拉格朗日粒子色散模型进行的最新反演相结合,以估算CH4排放。这项研究将印度半岛(21.5°N以南的陆地区域)的CH4排放量更新为〜10.63Terra克(Tg)CH4year-1,比现有的基于清单的排放量高0.13TgCH4year-1。在季节性尺度上,冬季,现有CH4排放清单的变化为0.12、0.05、0.055和0.28TgCH4year-1,季风前,季风和季风后季节分别。后排放的季节性变化的空间分布表明,与西部相比,印度半岛东部地区的排放量有所增加。对印度半岛三个站点的观测进行的研究提供了基于清单的CH4排放量估算的最新信息,并敦促对印度地区进行更多观测以准确估算通量的重要性。
    Accurate renditions of country-scale methane (CH4) emissions are critical in understanding the regional CH4 budget and essential for adapting national climate mitigation policies to curtail the atmospheric build-up of this greenhouse gas with high warming potential. India housing 30% of the Asian population is currently appraised as a region of CH4 source based on the inventories. To date, there have not been many reported efforts to estimate the regional CH4 emissions using direct measurements of boundary layer CH4 concentrations at multiple locations over India. Here, 2 years (2017-2018) of in situ CH4 observations from three distantly placed stations over the peninsular India is combined with state-of-the-art inversion using a Lagrangian particle dispersion model for the estimation of CH4 emission. This study updates CH4 emission over the peninsular India (land area south of 21.5°N) as ~ 10.63 Terra gram (Tg) CH4 year-1, which is 0.13 Tg CH4 year-1 higher than the existing inventory-based emission. On seasonal scale, the changes from the existing CH4 emission inventories are 0.12, 0.05, 0.055 and 0.28 Tg CH4 year-1 during winter, pre-monsoon, monsoon and post-monsoon seasons respectively. Spatial distributions of seasonal variability of posterior emissions suggest an enhancement over the eastern region of peninsular India compared to the western part. The study with observations from three stations over the peninsular India provides an update on the inventory-based estimation of CH4 emissions and urges the importance of more observations over the Indian region for the accurate estimation of fluxes.
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  • 文章类型: Journal Article
    硅纳米线场效应晶体管是用于检测微量不同生物物种的有前途的设备。我们介绍了生物敏感传感器的正向和反向建模的理论和计算方面。首先,我们引入了一个正向偏微分方程系统来模拟电学行为,其次,后向贝叶斯马尔可夫链蒙特卡罗方法用于识别未知参数,如目标分子的浓度。此外,介绍了一种基于多层前馈神经网络的机器学习算法。经训练的模型使得可以基于给定参数来预测传感器行为。
    Silicon nanowire field-effect transistors are promising devices used to detect minute amounts of different biological species. We introduce the theoretical and computational aspects of forward and backward modeling of biosensitive sensors. Firstly, we introduce a forward system of partial differential equations to model the electrical behavior, and secondly, a backward Bayesian Markov-chain Monte-Carlo method is used to identify the unknown parameters such as the concentration of target molecules. Furthermore, we introduce a machine learning algorithm according to multilayer feed-forward neural networks. The trained model makes it possible to predict the sensor behavior based on the given parameters.
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  • 文章类型: Journal Article
    Strict air pollution control measures were conducted during the Youth Olympic Games (YOG) period at Nanjing city and surrounding areas in August 2014. This event provides a unique chance to evaluate the effect of government control measures on regional atmospheric pollution and greenhouse gas emissions. Many previous studies have observed significant reductions of atmospheric pollution species and improvement in air quality, while no study has quantified its synergism on anthropogenic CO2 emissions, which can be co-reduced with air pollutants. To better understand to what extent these pollution control measures have reduced anthropogenic CO2 emissions, we conducted atmospheric CO2 measurements at the suburban site in Nanjing city from 1st July to 30th September 2014 and 1st August to 31st August 2015, obvious decrease in atmospheric CO2 was observed between YOG and the rest period. By coupling the a priori emission inventory with atmospheric transport model, we applied the scale factor Bayesian inversion approach to derive the posteriori CO2 emissions in YOG period and regular period. Results indicate CO2 emissions from power industry decreased by 45%, and other categories also decreased by 16% for manufacturing combusting, and 37% for non-metallic mineral production. Monthly total anthropogenic CO2 emissions were 9.8 (±3.6) × 109 kg/month CO2 for regular period and decreased to 6.2 (±1.9) × 109 kg/month during the YOG period in Nanjing city, with a 36.7% reduction. When scaling up to whole Jiangsu Province, anthropogenic CO2 emissions were 7.1 (±2.4) × 1010 kg/month CO2 for regular period and decreased to 4.4 (±1.2) × 1010 kg/month CO2 during the YOG period, yielding a 38.0% reduction.
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  • 文章类型: Journal Article
    In order to quantitatively predict nano- as well as other particle-size distributions, one needs to have both a mathematical model and estimates of the parameters that appear in these models. Here, we show how one can use Bayesian inversion to obtain statistical estimates for the parameters that appear in recently derived mechanism-enabled population balance models (ME-PBM) of nanoparticle growth. The Bayesian approach addresses the question of \"how well do we know our parameters, along with their uncertainties?.\" The results reveal that Bayesian inversion statistical analysis on an example, prototype Ir 0 n nanoparticle formation system allows one to estimate not just the most likely rate constants and other parameter values, but also their SDs, confidence intervals, and other statistical information. Moreover, knowing the reliability of the mechanistic model\'s parameters in turn helps inform one about the reliability of the proposed mechanism, as well as the reliability of its predictions. The paper can also be seen as a tutorial with the additional goal of achieving a \"Gold Standard\" Bayesian inversion ME-PBM benchmark that others can use as a control to check their own use of this methodology for other systems of interest throughout nature. Overall, the results provide strong support for the hypothesis that there is substantial value in using a Bayesian inversion methodology for parameter estimation in particle formation systems.
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  • 文章类型: Journal Article
    建立纵向胸部CT扫描的贝叶斯反演框架,可以对肺癌进行有效的多类分类。
    虽然大量训练医学图像的不可用性阻碍了肺癌分类器的性能,目的构建的深度网络在多类别分类中表现不佳。提出的框架采用粒子滤波方法来解决放射学特征对良性和癌性的非线性行为(阶段I,II,III,IV)结节,并执行有效的多类别分类(良性,早期癌症,晚期癌症)在后验概率函数方面。制定了包含诊断放射学特征的联合似然函数,该函数可以计算癌症的可能性及其病理阶段。拟议的研究还调查和验证了诊断特征,以准确区分早期阶段(I,II)和高级阶段(III,IV)癌症。
    所提出的随机框架在基准数据库上实现了86%的准确性,优于其他突出的癌症检测方法。
    提出的分类框架可以帮助放射科医生在早期阶段准确解释肺部CT图像,并可以导致癌症患者的及时医疗。
    To develop a Bayesian inversion framework on longitudinal chest CT scans which can perform efficient multi-class classification of lung cancer.
    While the unavailability of large number of training medical images impedes the performance of lung cancer classifiers, the purpose built deep networks have not performed well in multi-class classification. The presented framework employs particle filtering approach to address the non-linear behaviour of radiomic features towards benign and cancerous (stages I, II, III, IV) nodules and performs efficient multi-class classification (benign, early stage cancer, advanced stage cancer) in terms of posterior probability function. A joint likelihood function incorporating diagnostic radiomic features is formulated which can compute likelihood of cancer and its pathological stage. The proposed research study also investigates and validates diagnostic features to discriminate accurately between early stage (I, II) and advanced stage (III, IV) cancer.
    The proposed stochastic framework achieved 86% accuracy on the benchmark database which is better than the other prominent cancer detection methods.
    The presented classification framework can aid radiologists in accurate interpretation of lung CT images at an early stage and can lead to timely medical treatment of cancer patients.
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  • 文章类型: Journal Article
    We provide an overview of the methods that can be used for prediction under uncertainty and data fitting of dynamical systems, and of the fundamental challenges that arise in this context. The focus is on SIR-like models, that are being commonly used when attempting to predict the trend of the COVID-19 pandemic. In particular, we raise a warning flag about identifiability of the parameters of SIR-like models; often, it might be hard to infer the correct values of the parameters from data, even for very simple models, making it non-trivial to use these models for meaningful predictions. Most of the points that we touch upon are actually generally valid for inverse problems in more general setups.
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