calibration

校准
  • 文章类型: Journal Article
    我们提出了一种用于调查意大利地区(托斯卡纳)吸烟动态的隔室模型。根据1993年至2019年的当地数据对模型进行校准,我们估计了开始和戒烟的概率以及吸烟复发的概率。然后,我们预测了2043年前吸烟率的演变,并评估了归因死亡对死亡率的影响.我们介绍了关于该领域先前研究的新颖性元素,包括控制模型动力学的方程的正式定义和基于三次回归样条的吸烟概率的灵活建模。我们通过定义两步程序来估计模型参数,并通过参数引导来量化采样变异性。我们建议在滚动基础上实施交叉验证和基于方差的全局敏感性分析,以检查结果的稳健性并支持我们的发现。我们的结果表明男性吸烟率下降,女性吸烟率稳定,在接下来的二十年里。我们估计,在2023年,18%的男性和8%的女性死亡是由于吸烟。我们测试了该模型在评估不同烟草控制政策对吸烟率和死亡率的影响时的使用,包括最近在新西兰推出的无烟草发电禁令。
    We propose a compartmental model for investigating smoking dynamics in an Italian region (Tuscany). Calibrating the model on local data from 1993 to 2019, we estimate the probabilities of starting and quitting smoking and the probability of smoking relapse. Then, we forecast the evolution of smoking prevalence until 2043 and assess the impact on mortality in terms of attributable deaths. We introduce elements of novelty with respect to previous studies in this field, including a formal definition of the equations governing the model dynamics and a flexible modelling of smoking probabilities based on cubic regression splines. We estimate model parameters by defining a two-step procedure and quantify the sampling variability via a parametric bootstrap. We propose the implementation of cross-validation on a rolling basis and variance-based Global Sensitivity Analysis to check the robustness of the results and support our findings. Our results suggest a decrease in smoking prevalence among males and stability among females, over the next two decades. We estimate that, in 2023, 18% of deaths among males and 8% among females are due to smoking. We test the use of the model in assessing the impact on smoking prevalence and mortality of different tobacco control policies, including the tobacco-free generation ban recently introduced in New Zealand.
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  • 文章类型: Journal Article
    研究表明,车辆轨迹数据对于校准微观仿真模型是有效的。光检测和测距(LiDAR)技术提供高分辨率的3D数据,允许对周围环境进行详细的映射,包括道路几何形状,路边基础设施,和移动的物体,如车辆,骑自行车的人,和行人。与其他传统的轨迹数据收集方法不同,激光雷达的高速数据处理,精细的角度分辨率,测量精度高,在恶劣天气和弱光条件下的高性能使其非常适合需要实时响应的应用,比如自动驾驶汽车。这项研究提出了一个全面的框架,用于将LiDAR传感器数据集成到仿真模型中,并为主动安全分析提供准确的校准策略。从Lubbock的六个城市信号交叉口收集的LiDAR点云中提取车辆轨迹数据,德州,在美国。使用PTVVISSIM对每个研究交叉点进行建模,并进行校准以复制观察到的野外场景。在VISSIM中,使用了定向蛮力方法来校准Wiedemann1999模型的两个汽车跟随和两个车道改变参数,平均准确率为92.7%。从校准模型中提取的追尾冲突与十年历史碰撞数据集相结合,将其拟合到负二项(NB)模型中,以估计模型的参数。在所有六个十字路口中,后端冲突计数是观察到的后端碰撞频率的统计学显著预测因子(p值<0.05)。这项研究的结果为基于激光雷达的车辆轨迹数据的组合使用提供了一个框架,微观模拟,以及运输专业人员的替代安全评估工具。这种集成允许更准确和主动的安全评估,这对于设计更安全的运输系统至关重要,有效的交通控制策略,并预测未来的拥堵问题。
    Studies have shown that vehicle trajectory data are effective for calibrating microsimulation models. Light Detection and Ranging (LiDAR) technology offers high-resolution 3D data, allowing for detailed mapping of the surrounding environment, including road geometry, roadside infrastructures, and moving objects such as vehicles, cyclists, and pedestrians. Unlike other traditional methods of trajectory data collection, LiDAR\'s high-speed data processing, fine angular resolution, high measurement accuracy, and high performance in adverse weather and low-light conditions make it well suited for applications requiring real-time response, such as autonomous vehicles. This research presents a comprehensive framework for integrating LiDAR sensor data into simulation models and their accurate calibration strategies for proactive safety analysis. Vehicle trajectory data were extracted from LiDAR point clouds collected at six urban signalized intersections in Lubbock, Texas, in the USA. Each study intersection was modeled with PTV VISSIM and calibrated to replicate the observed field scenarios. The Directed Brute Force method was used to calibrate two car-following and two lane-change parameters of the Wiedemann 1999 model in VISSIM, resulting in an average accuracy of 92.7%. Rear-end conflicts extracted from the calibrated models combined with a ten-year historical crash dataset were fitted into a Negative Binomial (NB) model to estimate the model\'s parameters. In all the six intersections, rear-end conflict count is a statistically significant predictor (p-value < 0.05) of observed rear-end crash frequency. The outcome of this study provides a framework for the combined use of LiDAR-based vehicle trajectory data, microsimulation, and surrogate safety assessment tools to transportation professionals. This integration allows for more accurate and proactive safety evaluations, which are essential for designing safer transportation systems, effective traffic control strategies, and predicting future congestion problems.
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  • 文章类型: Journal Article
    碳水化合物是扁豆的主要成分,占其组成的60%以上。它们的含量受遗传因素的影响,根据品种不同的内容。这些化合物不仅与有趣的健康益处有关,但它们对扁豆衍生产品的技术功能特性也有重大影响。在这项研究中,使用近红外光谱(NIRS)来预测总碳水化合物的浓度,纤维,淀粉,总糖,果糖,研究蔗糖和棉子糖。为此,分析了六个不同品种的大精子(n=37)和小精子(n=43)小扁豆,对样本进行了整体和地面记录,并比较了两种记录方法的适用性。在使用改进的偏最小二乘回归方法开发校准模型之前,对不同的光谱和数学预处理进行了评估。交叉验证和外部验证。所开发的预测模型对总糖和果糖显示出优异的测定系数(RSQ>0.9),蔗糖,还有棉子糖.地面样品的记录可以获得更好的模型来校准淀粉含量(R>0.8),总糖和蔗糖(R>0.93),和棉子糖(R>0.91)。获得的结果证实,NIRS光谱区中有足够的信息来开发用于量化小扁豆中碳水化合物含量的预测模型。
    Carbohydrates are the main components of lentils, accounting for more than 60% of their composition. Their content is influenced by genetic factors, with different contents depending on the variety. These compounds have not only been linked to interesting health benefits, but they also have a significant influence on the techno-functional properties of lentil-derived products. In this study, the use of near-infrared spectroscopy (NIRS) to predict the concentration of total carbohydrate, fibre, starch, total sugars, fructose, sucrose and raffinose was investigated. For this purpose, six different cultivars of macrosperm (n = 37) and microsperm (n = 43) lentils have been analysed, the samples were recorded whole and ground and the suitability of both recording methods were compared. Different spectral and mathematical pre-treatments were evaluated before developing the calibration models using the Modified Partial Least Squares regression method, with a cross-validation and an external validation. The predictive models developed show excellent coefficients of determination (RSQ > 0.9) for the total sugars and fructose, sucrose, and raffinose. The recording of ground samples allowed for obtaining better models for the calibration of starch content (R > 0.8), total sugars and sucrose (R > 0.93), and raffinose (R > 0.91). The results obtained confirm that there is sufficient information in the NIRS spectral region for the development of predictive models for the quantification of the carbohydrate content in lentils.
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  • 文章类型: Journal Article
    为了更好地解决机械性能,有必要利用现代工具进行预测,模拟场景,优化决策。源整合。这将增加检测材料修改的能力,这些材料修改预示着损坏和/或预测将来很可能发生疲劳并扩展裂纹的阶段。通过协同实施基于NDE的协议来研究机械,疲劳和断裂行为而获得的预警结果将增强对经济上可持续的未来损害控制方案的准备。具体来说,这些预警结果将以重新拓扑模型的形式开发,并与FEA结合使用。本文介绍了校准的第一阶段和不同传感器系统的组合(摄影测量,激光扫描和应变计),用于创建适用于FEA软件故障预测的体积模型。测试对象是汽车悬架的两个组件,其上安装了应变仪以测量其在循环载荷下的变形。方法的校准是使用从摄影测量法和实验应变仪测量获得的模型进行的。
    To better address mechanical behavior, it is necessary to make use of modern tools through which it is possible to run predictions, simulate scenarios, and optimize decisions. sources integration. This will increase the capability of detecting material modifications that forerun damage and/or to forecast the stage in the future when very likely fatigue is initiating and propagating cracks. Early warning outcomes obtained by the synergetic implementation of NDE-based protocols for studying mechanical and fatigue and fracture behavior will enhance the preparedness toward economically sustainable future damage control scenarios. Specifically, these early warning outcomes will be developed in the form of retopologized models to be used coupled with FEA. This paper presents the first stage of calibration and the combination of a system of different sensors (photogrammetry, laser scanning and strain gages) for the creation of volumetric models suitable for the prediction of failure of FEA software. The test objects were two components of car suspension to which strain gauges were attached to measure its deformation under cyclic loading. The calibration of the methodology was carried out using models obtained from photogrammetry and experimental strain gauge measurements.
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  • 文章类型: Journal Article
    现代机器学习有可能从根本上改变生物过程的发展方式。特别是,横向知识转移方法,寻求利用历史过程中的数据来促进新产品的过程开发,提供重新思考当前工作流程的机会。在这项工作中,我们首先评估两种知识转移方法的潜力,元学习和独热编码,结合高斯过程(GP)模型。我们将他们的表现与仅在新流程数据上训练的GP进行比较,也就是说,本地模型。使用模拟的哺乳动物细胞培养数据,我们观察到,两种知识转移方法都表现出测试集误差,与局部模型相比,当两个模型时,四,或新产品的八个实验用于培训。随后,我们解决的问题是否可以通过利用现有知识更有效地设计新产品的实验。特别是,我们建议专门为新产品设计一些运行来校准知识转移模型,我们硬币校准设计的任务。我们提出了一个定制的目标函数来识别一组校准设计运行,利用历史产品演变过程中的差异。在两个模拟案例研究中,我们观察到,与普通实验设计相比,使用校准设计进行训练会产生相似的测试集误差.然而,前者需要大约少四倍的实验。总的来说,结果表明,当系统地将知识从一种产品传递到另一种产品时,工艺开发可以显着简化。
    Modern machine learning has the potential to fundamentally change the way bioprocesses are developed. In particular, horizontal knowledge transfer methods, which seek to exploit data from historical processes to facilitate process development for a new product, provide an opportunity to rethink current workflows. In this work, we first assess the potential of two knowledge transfer approaches, meta learning and one-hot encoding, in combination with Gaussian process (GP) models. We compare their performance with GPs trained only on data of the new process, that is, local models. Using simulated mammalian cell culture data, we observe that both knowledge transfer approaches exhibit test set errors that are approximately halved compared to those of the local models when two, four, or eight experiments of the new product are used for training. Subsequently, we address the question whether experiments for a new product could be designed more effectively by exploiting existing knowledge. In particular, we suggest to specifically design a few runs for the novel product to calibrate knowledge transfer models, a task that we coin calibration design. We propose a customized objective function to identify a set of calibration design runs, which exploits differences in the process evolution of historical products. In two simulated case studies, we observed that training with calibration designs yields similar test set errors compared to common design of experiments approaches. However, the former requires approximately four times fewer experiments. Overall, the results suggest that process development could be significantly streamlined when systematically carrying knowledge from one product to the next.
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  • 文章类型: Journal Article
    背景:风险预测模型通常用于辅助临床决策。当模型应用于新患者时,用于模型开发的小样本大小可能会损害模型性能。对于二元结果,校准斜率(CS)和平均绝对预测误差(MAPE)是两个关键指标,用于开发风险模型的样本量计算是基于这两个指标。CS量化模型过度拟合的程度,而MAPE评估个体预测的准确性。
    方法:最近,提出了两个公式来计算所需的样本量,考虑到发展数据的预期特征,如结果患病率和c统计量,以确保使用MLE拟合的模型中的CS和MAPE(在重复样本中)的预期将满足预定的目标值。在这篇文章中,我们使用模拟研究来评估这些公式的性能。
    结果:我们发现,当预期模型强度不太高时(c统计量<0.8),这两个公式都可以很好地工作。无论结果如何。然而,对于较高的模型强度,CS公式大大低估了样本量。例如,对于c统计量=0.85和0.9,样本量需要至少增加50%和100%,分别,以达到预期的CS目标。另一方面,MAPE公式倾向于高估高模型强度的样本量。这些结论对于较高的患病率比对于较低的患病率更为明显。当结果是进行审查时,得出了类似的结果。鉴于这些发现,我们提出了一种基于仿真的方法,在新的R包“samplesizedev”中实现,即使对于高模型强度,也能正确估计样本量。该软件还可以计算CS和MAPE的可变性,从而允许评估模型的稳定性。
    结论:校准和MAPE公式表明,当模型强度不太高时,通常适合使用的样品尺寸。然而,他们倾向于偏向于更高的模型优势,这在临床风险预测研究中并不少见。在那些场合,我们对样本量计算的拟议调整将是相关的。
    BACKGROUND: Risk prediction models are routinely used to assist in clinical decision making. A small sample size for model development can compromise model performance when the model is applied to new patients. For binary outcomes, the calibration slope (CS) and the mean absolute prediction error (MAPE) are two key measures on which sample size calculations for the development of risk models have been based. CS quantifies the degree of model overfitting while MAPE assesses the accuracy of individual predictions.
    METHODS: Recently, two formulae were proposed to calculate the sample size required, given anticipated features of the development data such as the outcome prevalence and c-statistic, to ensure that the expectation of the CS and MAPE (over repeated samples) in models fitted using MLE will meet prespecified target values. In this article, we use a simulation study to evaluate the performance of these formulae.
    RESULTS: We found that both formulae work reasonably well when the anticipated model strength is not too high (c-statistic < 0.8), regardless of the outcome prevalence. However, for higher model strengths the CS formula underestimates the sample size substantially. For example, for c-statistic = 0.85 and 0.9, the sample size needed to be increased by at least 50% and 100%, respectively, to meet the target expected CS. On the other hand, the MAPE formula tends to overestimate the sample size for high model strengths. These conclusions were more pronounced for higher prevalence than for lower prevalence. Similar results were drawn when the outcome was time to event with censoring. Given these findings, we propose a simulation-based approach, implemented in the new R package \'samplesizedev\', to correctly estimate the sample size even for high model strengths. The software can also calculate the variability in CS and MAPE, thus allowing for assessment of model stability.
    CONCLUSIONS: The calibration and MAPE formulae suggest sample sizes that are generally appropriate for use when the model strength is not too high. However, they tend to be biased for higher model strengths, which are not uncommon in clinical risk prediction studies. On those occasions, our proposed adjustments to the sample size calculations will be relevant.
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  • 文章类型: Journal Article
    汞(Hg)研究人员在理解大气汞方面取得了进展,特别是相对于可以代表大气中汞的2至20%的氧化汞(HgII)。过去10年发展的知识指出了当前测量大气Hg浓度和HgII化合物化学成分的方法存在的挑战。因为这些挑战,大气汞专家开会讨论了当前方法的局限性和克服这些局限性的途径,考虑到正在进行的研究。主要结论包括,目前测量气态氧化和颗粒结合汞的方法有局限性,并且需要开发新的方法来使这些测量更准确。开发用于测量HgII化学的分析方法是具有挑战性的。虽然最终目标是开发用于直接从环境空气中在线检测HgII的超灵敏方法,同时,需要新的表面,在该表面上可以定量地收集HgII并且可以从其可逆地解吸HgII以确定HgII化学。讨论和确定当前的限制,在这里描述,为前进的道路提供基础。由于大气是汞在全球分布的手段,准确校准的测量对于理解汞生物地球化学循环至关重要。
    Mercury (Hg) researchers have made progress in understanding atmospheric Hg, especially with respect to oxidized Hg (HgII) that can represent 2 to 20% of Hg in the atmosphere. Knowledge developed over the past ∼10 years has pointed to existing challenges with current methods for measuring atmospheric Hg concentrations and the chemical composition of HgII compounds. Because of these challenges, atmospheric Hg experts met to discuss limitations of current methods and paths to overcome them considering ongoing research. Major conclusions included that current methods to measure gaseous oxidized and particulate-bound Hg have limitations, and new methods need to be developed to make these measurements more accurate. Developing analytical methods for measurement of HgII chemistry is challenging. While the ultimate goal is the development of ultrasensitive methods for online detection of HgII directly from ambient air, in the meantime, new surfaces are needed on which HgII can be quantitatively collected and from which it can be reversibly desorbed to determine HgII chemistry. Discussion and identification of current limitations, described here, provide a basis for paths forward. Since the atmosphere is the means by which Hg is globally distributed, accurately calibrated measurements are critical to understanding the Hg biogeochemical cycle.
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  • 文章类型: Journal Article
    人乳头瘤病毒(HPV)是几乎所有宫颈癌病例的原因,一种每年杀死约34万妇女的疾病。从最初感染HPV到侵袭性宫颈癌发作的时间表跨越了几十年,对这一过程的观察性研究仅限于对癌前病变的治疗被拒绝或不充分的环境。这些研究对于了解HPV的自然史至关重要。建模可以提供有关HPV自然史的更多见解,特别是在地理环境中,已知影响宿主对HPV的免疫反应的因素的患病率不同,如艾滋病毒和烟草使用。在这项研究中,我们为撒哈拉以南非洲30个人口最多的国家创建模型,每个都有特定国家的人口,和行为输入。我们发现,如果我们假设所有国家的自然史参数完全相同,就不可能拟合数据,即使在考虑了人口和行为差异之后,但是我们可以通过为每个国家添加单个免疫能力参数来实现良好的匹配。我们的结果表明,宿主免疫反应的变化可能在解释国家之间宫颈癌负担的差异方面发挥作用。这反过来意味着更需要更多的地理上不同的数据收集,以了解HPV的自然史。
    Human papillomavirus (HPV) is the cause of almost all cases of cervical cancer, a disease that kills some 340,000 women per year. The timeline from initial infection with HPV to the onset of invasive cervical cancer spans decades, and observational studies of this process are limited to settings in which treatment of precancerous lesions was withheld or inadequate. Such studies have been critical for understanding the natural history of HPV. Modeling can shed additional insight on the natural history of HPV, especially across geographical settings with varying prevalence of factors known to affect the host-side immune response to HPV, such as HIV and tobacco use. In this study, we create models for the 30 most populous countries in Sub-Saharan Africa, each with country-specific demographic, and behavioral inputs. We found that it was not possible to fit the data if we assumed that the natural history parameters were exactly identical for all countries, even after accounting for demographic and behavioral differences, but that we could achieve a good fit with the addition of a single immunocompetence parameter for each country. Our results indicate that variation in host immune responses may play a role in explaining the differences in the burden of cervical cancer between countries, which in turn implies a greater need for more geographically diverse data collection to understand the natural history of HPV.
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  • 文章类型: Journal Article
    目的:强调使用校准加权来提高从“我们所有人”数据获得的估计值的精度,并增加“我们所有人研究计划”对社区的价值回报。
    方法:我们使用了我们所有人(2017-2022年)的数据并在两个示例中获得了患病率估计值:医疗环境中的歧视(N=41.875)和粮食不安全(N=82.266)。使用已知的人口比例(年龄,性别,种族/民族,居住地区,家庭年收入,和房屋所有权)来自2020年全国健康访谈调查。
    结果:大约37%的成年人在医疗环境中经历过歧视。大约20%没有看过医生的成年人报告说食物不安全,相比之下,14%的成年人经常看医生。
    结论:使用raking进行校准具有成本效益,并且在分析所有我们的数据时可能会导致更精确的估计。
    OBJECTIVE: To highlight the use of calibration weighting to improve the precision of estimates obtained from All of Us data and increase the return of value to communities from the All of Us Research Program.
    METHODS: We used All of Us (2017-2022) data and raking to obtain prevalence estimates in two examples: discrimination in medical settings (N = 41 875) and food insecurity (N = 82 266). Weights were constructed using known population proportions (age, sex, race/ethnicity, region of residence, annual household income, and home ownership) from the 2020 National Health Interview Survey.
    RESULTS: About 37% of adults experienced discrimination in a medical setting. About 20% of adults who had not seen a doctor reported being food insecure compared with 14% of adults who regularly saw a doctor.
    CONCLUSIONS: Calibration using raking is cost-effective and may lead to more precise estimates when analyzing All of Us data.
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  • 文章类型: Journal Article
    现代等温滴定量热仪器提供了很高的精度,但对于可比的精度,他们需要化学校准。对于热因素,一种推荐的方法是HCl进入弱碱TRIS。在用一个VP-ITC和两个Nano-ITC研究这个反应时,我们遇到了一些问题,最重要的是滴定剂体积不足Δv≈0.3μL,我们将其归因于注射器尖端中HCl的扩散损失。扩散问题的数学处理支持了这种解释。效果是通过可变v协议发现的,因此,它应该被用来适当地允许它在任何类似接近完成的反应中。我们还发现,碳酸盐污染和弱碱水解产生的OH-的影响可能比以前认为的更显著。为了便于在数据的最小二乘拟合中进行适当的加权,我们从复制数据中估计了数据方差函数。所有这三种仪器的低信号精度均为σ≈1μJ;Nano-ITC的滴定剂体积不确定性比VP-ITC大2倍。Thefinalheatfactorsremainsuncertainbymorethanthe~1%precisionoftheinstrumentsandareundulatesensitivetotheHClconcentration.
    Modern isothermal titration calorimetry instruments give great precision, but for comparable accuracy they require chemical calibration. For the heat factor, one recommended process is HCl into the weak base TRIS. In studying this reaction with a VP-ITC and two Nano-ITCs, we have encountered some problems, most importantly a titrant volume shortfall Δv ≈ 0.3 μL, which we attribute to diffusive loss of HCl in the syringe tip. This interpretation is supported by a mathematical treatment of the diffusion problem. The effect was discovered through a variable-v protocol, which thus should be used to properly allow for it in any reaction that similarly approaches completion. We also find that the effects from carbonate contamination and from OH- from weak base hydrolysis can be more significant that previously thought. To facilitate proper weighting in the least-squares fitting of data, we have estimated data variance functions from replicate data. All three instruments have low-signal precision of σ ≈ 1 μJ; titrant volume uncertainty is a factor of ∼2 larger for the Nano-ITCs than for the VP-ITC. The final heat factors remain uncertain by more than the ∼1% precision of the instruments and are unduly sensitive to the HCl concentration.
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