sensitivity analysis

敏感性分析
  • 文章类型: Journal Article
    地下水在满足不同需求方面的关键作用,包括喝酒,工业,农业,强调了有效资源管理的紧迫性。过量的地下水开采,特别是在沿海地区,包括伊朗西北部的Urmia平原,破坏含水层内淡水和盐水边界之间的平衡。控制海水入侵的影响参数-地下水发生(G),含水层导水率(A),地下水位高于平均海平面的高度(L),与海岸的距离(D),海水入侵现状的影响(I),和饱和含水层的厚度(T)-合并以形成沿海含水层的GALDIT脆弱性指数。这项研究通过结合两个额外的水文地质变量:水力梯度(i)和抽水率(P)来丰富GALDIT框架。此扩展生成了七个不同的漏洞图(GALDIT,GAIDIT,GAIDIT-P,GALDIT-i,GALDIT-iP,GALDIT-P,GAPDIT).在Urmia平原,传统的GALDIT指数显示的脆弱性值从2到8.1不等,分为从微不足道到非常高的六类脆弱性。然而,修改后的指数,GAiDIT和GAiDIT-P,产生三级分类,从低到高的脆弱性。在GALDIT-i和GALDIT-iP中引入\"i\"和\"P\"参数,提高了漏洞映射的精度,改变类分布和加强脆弱性评级。东方,中央,Urmia平原的沿海地区显示出高到非常高的脆弱性水平,与西部地区的脆弱性较低相反。GALDIT-P(r=0.82)和GALDIT-iP(r=0.81)指数均与Cl浓度有很强的相关性,从而提高了比传统的GALDIT指数(r=0.72)的映射精度。敏感性分析突出了“i”参数的关键影响,建议应修改其权重。参数重新校准用于放大“G”的重要性,\"\"L,\"\"D,\"和\"i\"参数,同时减少其他人。多个水文地质变量的集成大大提高了地下水脆弱性评估的精度。
    The critical role of groundwater in meeting diverse needs, including drinking, industrial, and agricultural, highlights the urgency of effective resource management. Excessive groundwater extraction, especially in coastal regions including Urmia Plain in NW Iran, disrupts the equilibrium between freshwater and saline boundaries within aquifers. Influential parameters governing seawater intrusion-groundwater occurrence (G), aquifer hydraulic conductivity (A), the height of groundwater level above the mean sea level (L), distance from the shore (D), impact of the existing status of seawater intrusion (I), and thickness of the saturated aquifer (T)-merge to shape the GALDIT vulnerability index for coastal aquifers. This study enriches the GALDIT framework by incorporating two additional hydrogeological variables: hydraulic gradient (i) and pumping rate (P). This expansion produces seven distinct vulnerability maps (GALDIT, GAiDIT, GAiDIT-P, GALDIT-i, GALDIT-iP, GALDIT-P, GAPDIT). In the Urmia Plain, the traditional GALDIT index reveals vulnerability values ranging from 2 to 8.1, categorized into six classes from negligible to very high vulnerability. However, the modified indices, GAiDIT and GAiDIT-P, yield a three-class categorization, ranging from low to high vulnerability. The introduction of the \"i\" and \"P\" parameters in GALDIT-i and GALDIT-iP enhances the precision of vulnerability mapping, altering class distribution and intensifying vulnerability ratings. The eastern, central, and coastal areas of the Urmia Plain demonstrate high to very high vulnerability levels, in contrast to the lower vulnerability observed in the western regions. Both the GALDIT-P (r = 0.82) and GALDIT-iP (r = 0.81) indices show strong correlations with Cl concentration, thereby improving mapping accuracy over the traditional GALDIT index (r = 0.72). A sensitivity analysis highlights the critical influence of the \"i\" parameter, suggesting its weighting should be revised. Parameter recalibration serves to amplify the significance of \"G,\" \"L,\" \"D,\" and \"i\" parameters, while diminishing others. The integration of multiple hydrogeological variables considerably enhances the precision of groundwater vulnerability assessments.
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  • 文章类型: Journal Article
    结核病(TB)仍然是一个重要的全球健康问题,需要有效的控制策略。本文提出了一个数学模型来评估在结核病控制中医用口罩使用和病例检测的比较有效性。该模型被构造为一个常微分方程系统,并结合了结核病动力学的关键方面,包括缓慢快速的进展,医用口罩使用,案例检测,治疗干预措施和有症状和无症状病例之间的区别。结核病控制的一个关键目标是确保复制数量,Rc,如果Rc超过1,则保持低于1以实现结核病消除或持久性。我们的数学分析揭示了当Rc=1表示结核病控制策略的关键节点时,存在跨临界分叉。这些结果证实,病例检测在减少结核病地方性平衡中有症状的个体的地方性人群中的有效性取决于超过临界阈值。此外,我们的模型是使用印度尼西亚每10万人口的结核病年发病率数据进行校准的,印度,莱索托和安哥拉。我们采用了Bootstrap重采样残差方法来评估参数估计值固有的不确定性,从而提供了参数值的全面分布。尽管新发病率呈下降趋势,这四个国家的再现数大于1,表明在有正在进行的结核病控制方案的情况下,结核病病例持续存在.我们将部分秩相关系数与拉丁超立方抽样方法结合使用,对每个国家/地区的每个拟合参数的Rc参数进行全局敏感性分析。我们发现,与病例检测实施相比,医疗面罩的使用对降低Rc更敏感。为了进一步深入了解必要的控制策略,我们制定了最优控制,并研究了我们模型的成本-效果分析,以调查病例检测和使用医用口罩作为控制措施对结核病传播的影响.成本效益分析表明,将这些干预措施结合起来是结核病控制最具成本效益的策略。我们的研究结果强调了医用口罩及其功效以及病例检测在塑造结核病控制动态方面的至关重要性。阐明管理控制再现数的主要参数。我们设想,如果由参与结核病控制工作的政策制定者和医疗保健从业人员实施,我们的发现将对结核病控制产生影响并至关重要。
    Tuberculosis (TB) remains a significant global health concern, necessitating effective control strategies. This article presents a mathematical model to evaluate the comparative effectiveness of medical mask usage and case detection in TB control. The model is constructed as a system of ordinary differential equations and incorporates crucial aspects of TB dynamics, including slow-fast progression, medical mask use, case detection, treatment interventions and differentiation between symptomatic and asymptomatic cases. A key objective of TB control is to ensure that the reproduction number, R c , remains below unity to achieve TB elimination or persistence if R c exceeds 1. Our mathematical analysis reveals the presence of a transcritical bifurcation when the R c = 1 signifies a critical juncture in TB control strategies. These results confirm that the effectiveness of case detection in diminishing the endemic population of symptomatic individuals within a TB-endemic equilibrium depends on exceeding a critical threshold value. Furthermore, our model is calibrated using TB yearly case incidence data per 100 000 population from Indonesia, India, Lesotho and Angola. We employed the bootstrap resampling residual approach to assess the uncertainty inherent in our parameter estimates which provides a comprehensive distribution of the parameter values. Despite a declining trend in new incidence, these four countries exhibit a reproduction number greater than 1, indicating persistent TB cases in the presence of ongoing TB control programmes. We employ the partial rank correlation coefficient in conjunction with the Latin hypercube sampling method to conduct a global sensitivity analysis of the R c parameter for each fitted parameter in every country. We find that the medical mask use is more sensitive to reduce R c compared with the case detection implementation. To further gain insight into the necessary control strategy, we formulated an optimal control and studied the cost-effectiveness analysis of our model to investigate the impact of case detection and medical mask use as control measures in TB spread. Cost-effectiveness analysis demonstrates that combining these interventions emerges as the most cost-effective strategy for TB control. Our findings highlight the critical importance of medical masks and their efficacy coupled with case detection in shaping TB control dynamics, elucidating the primary parameter of concern for managing the control reproduction number. We envisage our findings to have implications and be vital for TB control if implemented by policymakers and healthcare practitioners involved in TB control efforts.
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  • 文章类型: Journal Article
    建设后水库的温度分层会对环境产生重大影响。开发了MIKE11-2DV模型来模拟新建立的秦村水库的年度水温变化。进行灵敏度分析以评估八个关键参数对模型性能的影响。线性和玻尔兹曼曲线用于拟合水温曲线并提取四个特征以进行定量灵敏度分析。此外,对两种不同的退出情况进行了比较分析。SSI用于评估热分层。MIKE11-2DV模型在模拟单质储层中的流体动力学和水温方面表现出很高的准确性。敏感性分析显示模型参数之间的敏感性水平不同。具体来说,低水温对垂直粘度因子高度敏感,但对水平因子几乎不敏感。此外,比尔定律中的光衰减系数和常数对温跃层有显著影响。辐射和蒸发参数影响整个水温,保持稳定的“形状”。此外,初始情景模拟结果表明,初始水温显著影响低流。基于两种取水方案的热结构分析表明,与单级取水相比,多级取水具有更高的施密特稳定性指数(SSI)和更长的分层期。在鱼类繁殖季节,使用多级取水导致出口温度高于单级取水。SSI反映了时间和空间异质性。在SSI和空气温度之间观察到滞后行为,磁滞回线的方向受不同取水水平的影响。在多级取水方案中,在较深的储层段观察到了增强的滞后现象。这些发现为解释储层的热分层提供了新的见解。
    The temperature stratification in reservoirs post-construction carries substantial environmental implications. A MIKE11-2DV model was developed to simulate yearly water temperature changes in the newly established Qincun Reservoir. Sensitivity analysis was performed to assess the influence of eight key parameters on the model\'s performance. Linear and Boltzmann curves were employed to fit water temperature profiles and extract four features for quantitative sensitivity analyses. In addition, a comparative analysis was conducted considering two different withdrawal scenarios. The SSI were employed for the assessment of thermal stratification. The MIKE11-2DV model demonstrated a high accuracy in simulating hydrodynamics and water temperature in the monomictic reservoir. A sensitivity analysis showed varying levels of sensitivity among model parameters. Specifically, the hypolimnetic water temperature was highly sensitive to the vertical viscosity factor but almost insensitive to the horizontal factor. Additionally, the light attenuation coefficient and constant in Beer\'s law significantly influenced the thermocline. Radiation and evaporation parameters affected overall the water temperature, maintaining a stable \"shape\". Furthermore, the initial scenarios simulation results showed that initial water temperature significantly affected the hypolimnion. The analysis of the thermal structure based on two water intake scenarios revealed that multi-level withdrawal had a higher Schmidt\'s Stability Index (SSI) and a longer stratified period compared to single-level withdrawal. During the fish breeding season, using multi-level water intake resulted in higher outlet temperatures than single-level water intake. The SSI reflected both temporal and spatial heterogeneity. Hysteresis behavior was observed between SSI and air temperature, with the hysteresis loops\' direction being influenced by different water intake levels. Enhanced hysteresis was observed in deeper reservoir segments during multi-level water intake scenario. These findings provide novel insights for interpreting thermal stratification in reservoirs.
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  • 文章类型: Journal Article
    本文应用简化的Green-Ampt(GA)入渗模型对Maga土坝体内的渗流过程进行数值模拟,位于喀麦隆北部,在降雨条件下。参数化方法可以预测构成土坝及其附近区域的各种纹理的渗透参数。土壤质地的影响,渗透系数,通过运行ExcelVBA代码进行数值模拟,研究了降雨强度和初始水分对渗透率和累积深度的影响。然后使用文献中提出的优化程序来改善GA模型参数和预测精度。还对入渗模型参数进行了实例敏感性分析。初始和饱和水含量,降雨强度和饱和渗透系数已被确定为模型预测的最多影响参数,输入之间有明显的相互作用。上述输入的主要影响和相互作用的贡献在总方差的68.8%和90.03%之间。已将数值结果与从撒哈拉以南主要土壤模拟降雨的真实案例中获得的文献中获得的实验结果进行了比较。结果表明,数值模拟分别低估了一个和四个模拟降雨序列的流体动力学参数的60%和56.25%,相对误差(RE)在-76.22%和300.25%之间。对于预测的流体动力学参数的53.13%,RE值在-23.90%至12.75%之间,获得了最具代表性的结果。得到的结果证明,简化的GA模型在预测铁质和退化的垂直土壤的渗流过程中表现出可接受的准确性。因此,本研究有助于理解数值模拟工具在模拟和预测地下渗流现象中的作用,在重大气候变化的背景下,洪水风险高的地区。
    The present paper applies a simplified Green-Ampt (GA) infiltration model for the numerical modelling of seepage processes within the body of the Maga earth dam, located in the Far-North Cameroon, under rainfall conditions. The parametrization approach makes possible the predictions of infiltrations parameters for various textures that constitute the body of earth dam and its vicinities. The effects of soil texture, permeability coefficient, rain intensity and initial moisture on infiltration rate and cumulative depth are investigated using numerical simulations carried out by running an Excel VBA code. A proposed optimization procedure of the literature is then used to improve the GA model parameters and accuracy of predictions. A case sensitivity analysis of the infiltration model parameters has also been made. Initial and saturated water contents, rain intensity and permeability coefficient at saturation have been identified as the most influents parameters for the model predictions, with obvious interactions between inputs. The contribution of main effects and interactions of above inputs ranges between 68.8 % and 90.03 % of the total variance. Comparisons of numerical results with the experimental ones obtained from the literature on real cases of simulated rainfall on main sub-Saharan soils have been done. The results show that numerical simulations underestimated 60 % and 56.25 % of the hydrodynamics parameters respectively for one and four simulated rain-sequence with relative errors (RE) ranging between -76.22 % and 300.25 %. The most representative results were obtained for 53.13 % of the predicted hydrodynamics parameters with RE value ranging between -23.90 % and 12.75 %. The obtained results proved that, the simplified GA model exhibited an acceptable accuracy in predicting seepage processes for ferruginous and degraded vertic soils. Therefore, the present study contributes to understand the role of numerical simulations tools in modelling and predicting subsurface phenomenon as seepage, for areas with high floods risks in a context of significant climate changes.
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  • 文章类型: Journal Article
    在中国,地面臭氧(O3)已成为新兴问题。由于其复杂的形成机制,了解影响因素的影响对于有效控制污染至关重要。本研究旨在展示和展示数据驱动技术的实用性,该技术将机器学习(ML)模型与SHapley加法扩张(SHAP)方法耦合在O3模拟和灵敏度分析中。根据每小时测量的O3及其主要前体浓度,以及南京北部地区的气象因素,中国,建立了光梯度增压机(LightGBM)模型来模拟不同季节的O3浓度,并应用SHAP方法对影响因素对O3形成的影响进行了深入分析。结果表明,ML模型在模拟O3浓度方面具有可靠的性能,测量和模拟之间的确定系数(R2)大于0.80,并且通过SHAP方法在季节和昼夜时间尺度上合理地评估了影响因素的影响。人们发现,尽管挥发性有机化合物(VOC)和氮氧化物(NOx),以及温度和相对湿度,通常是主要影响因素,在不同的季节和一天中的时间,它们对O3形成的敏感性差异很大。这项研究表明,数据驱动的机器学习模型是一种可行的技术,可以在一定程度上作为执行机制分析的替代方法。并且在空气污染控制的问题研究和决策中都具有巨大的潜力。
    Ground-level ozone (O3) has been an emerging concern in China. Due to its complicated formation mechanisms, understanding the effects of influencing factors is critical for making effective efforts on the pollution control. This study aims to present and demonstrate the practicality of a data-driven technique that applies a machine learning (ML) model coupled with the SHapley Additive exPlanations (SHAP) approach in O3 simulation and sensitivity analysis. Based on hourly measured concentrations of O3 and its major precursors, as well as meteorological factors in a northern area of Nanjing, China, a Light Gradient Boosting Machine (LightGBM) model was established to simulate O3 concentrations in different seasons, and the SHAP approach was applied to conduct in-depth analysis on the impacts of influencing factors on O3 formation. The results indicated a reliable performance of the ML model in simulating O3 concentrations, with the coefficient of determination (R2) between the measured and simulated larger than 0.80, and the impacts of influencing factors were reasonably evaluated by the SHAP approach on both seasonal and diurnal time scales. It was found that although volatile organic compounds (VOCs) and nitrogen oxides (NOx), as well as temperature and relative humidity, were generally the main influencing factors, their sensitivities to O3 formation varied significantly in different seasons and with time of the day. This study suggests that the data-driven ML model is a practicable technique and may act as an alternative way to perform mechanism analysis to some extent, and has immense potential to be applied in both problem research and decision-making for air pollution control.
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  • 文章类型: Journal Article
    温室气体(GHG)可以在不同的空间和时间尺度上由广泛的人为活动产生。特别是,城市地区的排放是温室气体的进口来源。城市是一个由各种组成部分和过程组成的复杂系统。已经努力减少城市温室气体排放。然而,缺乏有效评估此类排放的可用方法。许多城市来源和可能影响排放的因素仍然未知。在本研究中,对市政活动的温室气体排放量进行了评估。建立了城市温室气体排放评估模型。根据收集的数据,进行了一个案例研究,以评估城市温室气体排放。综合评估包括运输排放,电力消耗,天然气,废物处理,和废水处理。这些部门的温室气体排放量在不同年份有所不同。本研究为城市温室气体排放综合评价提供了一种新的方法。研究结果可以帮助更好地了解排放过程并确定主要排放源。
    在线版本包含补充材料,可在10.1186/s40068-024-00341-y获得。
    Greenhouse gases (GHGs) can be produced from a broad range of anthropogenic activities at different spatial and temporal scales. In particular, emissions from urban area are an import source of GHGs. City is a complicated system consisting of various component and processes. Efforts have been made to reduce urban GHG emissions. However, there is a lack of available methods for effective assessment of such emissions. Many urban sources and factors which can influence the emissions are still unknown. In the present study, the GHG emissions from municipal activities was assessed. A model for the assessment of urban GHG emissions was developed. Based on the collected data, a case study was conducted to evaluate urban GHG emissions. The comprehensive assessment included the emissions from transportation, electricity consumption, natural gas, waste disposal, and wastewater treatment. There was a variation for GHG emissions from these sectors in different years. This study provided a new approach for comprehensive evaluation of urban GHG emissions. The results can help better understand the emission process and identify the major emission sources.
    UNASSIGNED: The online version contains supplementary material available at 10.1186/s40068-024-00341-y.
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  • 文章类型: Journal Article
    本调查通过采用层次分析法(AHP)的综合方法描绘了Jhargram地区的地下水潜力区(GPZ),遥感,地理信息系统(GIS)。12个参数用于基于地下水潜力指数的GPZ分析,在多重共线性测试之后。GPZ的分类产生了五个不同的类别:非常差,可怜的,中度,不错,非常好。通过接收器操作特性(ROC)进行验证,并与井井产量数据进行交叉验证,确认了78.4%和84%的预测准确性,分别。空间分布分析表明,30.39%,30.86%,13.19%的调查区域属于贫困人口,中度,和良好的潜力区,分别,而15.86%和9.69%被归类为非常差和非常好的GPZ。敏感性分析强调了地质学的重要性,高程,地貌学,斜坡,和线条密度作为影响参数;消除任何单个参数会导致GPZ分类发生重大变化。调查最终制定了旨在为政策举措提供信息的区块可持续地下水管理蓝图。
    The present investigation delineates groundwater potential zones (GPZ) in the Jhargram district through an integrated approach employing analytical hierarchical process (AHP), remote sensing, and geographical information systems (GIS). Twelve parameters were utilized for GPZ analysis based on the Groundwater Potential Index, subsequent to multicollinearity testing. Classification of GPZ yielded five distinct categories: very poor, poor, moderate, good, and very good. Validation through receiver operating characteristics (ROC) and cross-validation with borewell yield data affirmed prediction accuracies of 78.4% and 84%, respectively. Spatial distribution analysis revealed that 30.39%, 30.86%, and 13.19% of the surveyed area fell within the poor, moderate, and good potentiality zones, respectively, whereas 15.86% and 9.69% were categorized as very poor and very good GPZs. Sensitivity analysis highlighted the significance of geology, elevation, geomorphology, slope, and lineament density as influencing parameters; elimination of any single parameter engendered significant alterations in the GPZ classification. The investigation culminated in the formulation of a block-wise sustainable groundwater management blueprint designed to inform policy initiatives.
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  • 文章类型: Journal Article
    在本文中,我们提出了一种基于投资组合决策分析的结构化方法,以支持在选择有效投资组合时考虑行动之间的相互依赖性(即相互作用)。建模交互的主要挑战之一是动作对之间的可能数量随着动作数量的增加而呈指数增长。在环境管理方面,这些问题可能包括数十种可能的行为,可能导致它们之间数百种成对的相互作用。例如,缓解气候变化的战略可以包括不同部门改进技术的各种行动,减少排放和碳封存。我们的方法旨在通过最初根据特定的启发式方法选择一个简短的动作列表,并专注于在所选的一组动作中对交互进行建模,从而减轻评估交互的负担。该方法的另一个特点是使用对互动的整体评估,以进一步减少进行评估的利益相关者的认知负荷。作为一个可能的缺点,这些特征可能会增加与模型结果相关的不精确性。为了分析这种不精确的影响,我们提出了一种方法来进行敏感性分析的基础上,如何集中考虑的相互作用将在建模。到2035年,在与芬兰碳中和北萨沃地区路线图相关的案例中测试了该方法的适用性。该方法有助于在将路线图的行动付诸实践时更好地理解协同作用和取舍,预计这将在准备和适应气候变化方面产生更好的结果。
    In this paper, we present a structured approach based on portfolio decision analysis to support the consideration of interdependencies between actions (i.e. interactions) in the selection of an efficient portfolio. One of the main challenges in modelling interactions is that the possible number of them between the pairs of actions increases exponentially with the number of actions. In environmental management, the problems can include tens of possible actions potentially leading to hundreds of pairwise interactions between them. For example, a strategy for mitigating climate change can consist of various actions in different sectors for improving technology, reducing emissions and the sequestration of carbon. Our approach aims to reduce the burden of assessing interactions by initially selecting a shortlist of actions based on specific heuristics and focusing on modelling interactions exclusively within this chosen set of actions. Another feature of the approach is the use of holistic evaluation of interactions to further reduce the cognitive load of stakeholders making the assessment. As a possible disadvantage, these features may increase the imprecision related to the results of the model. To analyse the impacts of this imprecision, we propose a way to carry out sensitivity analysis on the basis of how intensively the interactions would be taken into account in the modelling. The applicability of the approach was tested in a case related to the roadmap to a carbon neutral North Savo region in Finland by the year 2035. The approach helped to better understand synergies and trade-offs when putting the actions of the roadmap into practice, which is expected to lead to better results in terms of preparedness and adaptation to climate change.
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  • 文章类型: Journal Article
    背景:在国家出生缺陷预防研究(NBDPS)中观察到的某些关联与其他研究形成对比,或者来自具有混合发现的领域,包括不降低脊柱裂的几率与周觉叶酸补充,使用昂丹司琼可适度增加腭裂的几率,母亲吸烟可降低尿道下裂的几率。
    目的:研究差异参与的合理性和程度,以产生在NBDPS中观察到的效果估计。
    方法:我们在文献中搜索了与这些暴露和参与相关的因素,并进行了确定性定量偏倚分析。我们根据内部和外部报告估计了病例控制参与和预期暴露率,分别。对于叶酸-脊柱裂和昂丹司琼-腭裂分析,我们根据先前的研究假设了真实比值比(OR),并量化了暴露程度过高(或过低),以产生NBDPS中的粗OR(cOR).对于吸烟尿道下裂的分析,我们估计了消除关联所需的选择偏倚程度以及最大潜在有害OR.
    结果:在我们的假设下(参与,暴露患病率,真OR),参与者中叶酸的使用比例过高,昂丹司琼的使用和吸烟比例过低.与暴露对照相比,暴露于叶酸的脊柱裂病例需要≥1.2倍,才能产生观察到的无效cOR。如果真正的OR为空,则昂丹司琼暴露的left裂病例的参与可能性需要比暴露的对照高1.6倍。与暴露对照组相比,暴露于吸烟的尿道下裂病例参与的可能性要低≥1.2倍,以使关联错误地表现出保护性(选择偏差的上限调整了吸烟尿道下裂OR=2.02)。
    结论:差异参与可以部分解释在NBDPS中观察到的某些关联,但问题仍然是为什么。其他系统误差(如暴露错误分类)的潜在影响可以通过其他研究来了解。
    BACKGROUND: Certain associations observed in the National Birth Defects Prevention Study (NBDPS) contrasted with other research or were from areas with mixed findings, including no decrease in odds of spina bifida with periconceptional folic acid supplementation, moderately increased cleft palate odds with ondansetron use and reduced hypospadias odds with maternal smoking.
    OBJECTIVE: To investigate the plausibility and extent of differential participation to produce effect estimates observed in NBDPS.
    METHODS: We searched the literature for factors related to these exposures and participation and conducted deterministic quantitative bias analyses. We estimated case-control participation and expected exposure prevalence based on internal and external reports, respectively. For the folic acid-spina bifida and ondansetron-cleft palate analyses, we hypothesized the true odds ratio (OR) based on prior studies and quantified the degree of exposure over- (or under-) representation to produce the crude OR (cOR) in NBDPS. For the smoking-hypospadias analysis, we estimated the extent of selection bias needed to nullify the association as well as the maximum potential harmful OR.
    RESULTS: Under our assumptions (participation, exposure prevalence, true OR), there was overrepresentation of folic acid use and underrepresentation of ondansetron use and smoking among participants. Folic acid-exposed spina bifida cases would need to have been ≥1.2× more likely to participate than exposed controls to yield the observed null cOR. Ondansetron-exposed cleft palate cases would need to have been 1.6× more likely to participate than exposed controls if the true OR is null. Smoking-exposed hypospadias cases would need to have been ≥1.2 times less likely to participate than exposed controls for the association to falsely appear protective (upper bound of selection bias adjusted smoking-hypospadias OR = 2.02).
    CONCLUSIONS: Differential participation could partly explain certain associations observed in NBDPS, but questions remain about why. Potential impacts of other systematic errors (e.g. exposure misclassification) could be informed by additional research.
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  • 文章类型: Journal Article
    In this modern era where Industry 4.0, plays a crucial role in enhancing productivity, quality, and resource utilization by digitalizing and providing smart operation to industrial systems. Therefore, there is a need to establish a framework that enhances productivity and quality of work to achieve the net-zero from industry. In this study, a comprehensive and generic analytical framework has been established to mitigate or lessen the research and technological gap in the manufacturing sector. In addition to that, the key stages involved in artificial intelligence (AI) based modelling and optimization analysis for manufacturing systems have also been incorporated. To assess the proposed AI framework, electric discharge machining (EDM) as a case study has been selected. The focus enlightens the emergence of optimizing the material removal rate (MRR) and surface roughness (SR) for Inconel 617 (IN617) material. A full factorial design of the experiment was carried out for experimentation. After that, an artificial neural network (ANN) as a modelling framework is selected, and fine-tuning of hyperparameters during training has been carried out. To validate the predictive performance of the trained models, an external validation (Valext) test has been conducted. Through sensitivity analysis (SA) on the developed AI framework, the most influential factors affecting MRR and SR in EDM have been identified. Specifically, powder concentration (Cp) contributes the most to the percentage significance, accounting for 79.00 % towards MRR, followed by treatment (16.35 %) and 4.67 % surfactant concentration (Sc). However, the highest % significance in SR is given by Sc (36.86 %), followed by Cp (33.23 %), and then treatment (29.90 %), respectively. Furthermore, a parametric optimization has been performed using the framework and found that MRR and SR are 93.75 % and 58.90 % better than experimental data. This successful performance optimization proposed by the framework has the potential for application to other manufacturing systems.
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