2D model

2D 模型
  • 文章类型: Journal Article
    当前的大坝破坏分析方法采用确定性方法。将这些方法应用于混凝土面板堆石坝(CFRD)充满了巨大的不确定性,特别是在自然灾害的背景下。在当今世界,降雨和地震的频率和震级更高。在文学中,大坝的完全倒塌是以定义大坝溃坝流出量的溃坝参数为模型,但与自然灾害的重现期无关。随着更多的新水坝被修建以控制板内地震区的洪水,这项研究提出了一种新的方法来推导广义大坝溃坝参数的CFRD基于结构分析的有限元模型(FEM)模拟峰值地面加速度对应的475和2475年的回报期。此外,使用2D流体动力学模拟对不同重现期的降雨和地震的发生进行建模。结果表明,广义溃坝参数对于地震期间规划和管理CFRD具有重要意义。该研究强调利用结构分析输出进行大坝溃坝的水力建模,这将导致更具体和准确的溃坝参数。此外,研究表明,洪水风险和严重程度将随着地震强度和降雨量的增加而增加。减灾策略可以通过根据发生概率考虑降雨和地震的综合发生来优化,使用案例研究大坝进行演示。研究的另一个重要成果是溃坝期间土壤饱和条件的影响,这表明大坝破坏位置40公里内的地区可能受到最严重的影响。
    Current methods of dam breach analyses adopt a deterministic approach. Applying these methods to Concrete Faced Rockfill Dams (CFRD) is fraught with huge levels of uncertainty, especially in the context of natural hazards. The frequency and magnitude of rainfall and earthquakes are higher in today\'s world. In the literature, the complete collapse of dams is modelled on dam breach parameters that define the dam break outflow but are not related to the return periods of natural hazards. As more new dams are constructed to control the floods in intra-plate seismic regions, this study presents a novel approach to the derivation of generalized dam break parameters for CFRD based on the structural analysis of Finite Element Model (FEM) simulations for peak ground accelerations corresponding to 475 and 2475 year return periods. Furthermore, the occurrence of rainfall and earthquake for different return periods are modelled using 2D hydrodynamic simulations. Results show the significance of generalized dam breach parameters for planning and managing CFRDs during earthquakes. The study emphasizes the utilization of structural analysis outputs for the hydraulic modeling of dam breaks, which will result in more specific and accurate dam break parameters. Additionally, the study has shown that the flood risk and the severity will increase with the intensity of earthquake and rainfall magnitudes. Disaster mitigation strategies can be optimized by considering the integrated occurrence of rainfall and earthquakes based on the probability of occurrence, demonstrated using a case-study dam. Another significant outcome of the study is the effect of soil saturation condition during a dam break, which reveals that areas within 40 km of the dam breach location might be worst affected.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Multicenter Study
    背景:术前应预测肝性脑病(HE),以确定经颈静脉肝内门体分流术(TIPS)的合适候选者,而不是一线治疗。本研究旨在构建基于3D评估的模型来预测TIPS后的显性HE。
    方法:在这项多中心队列研究中,487名接受TIPS的患者被细分为训练数据集(来自三家医院的390例)和外部验证数据集(来自另外两家医院的97例)。候选因素包括临床,血管,以及2D和3D数据。结合最小绝对收缩和算子方法,支持向量机,和等渗回归的概率校准,我们构建了四个预测模型:临床,2D,3D,和组合模型。将它们的辨别和校准进行比较,以确定最佳模型,进行亚组分析。
    结果:3D模型显示出比2D模型更好的辨别力(训练:0.719vs.0.691;验证:0.730vs.0.622)。结合临床和3D因素的模型优于临床和3D模型(训练:0.802vs.0.735vs.0.719;验证:0.816与0.723vs.0.730;所有p<0.050)。此外,组合模型具有最佳的校准。最佳模型的性能不受总胆红素水平的影响,Child-Pugh评分,氨水平,或提示指示。
    结论:肝脏和脾脏的3D评估提供了额外的信息来预测明显的HE,改善适合患者的TIPS机会。3D评估也可用于与肝硬化相关的类似研究。
    BACKGROUND: Overt hepatic encephalopathy (HE) should be predicted preoperatively to identify suitable candidates for transjugular intrahepatic portosystemic shunt (TIPS) instead of first-line treatment. This study aimed to construct a 3D assessment-based model to predict post-TIPS overt HE.
    METHODS: In this multi-center cohort study, 487 patients who underwent TIPS were subdivided into a training dataset (390 cases from three hospitals) and an external validation dataset (97 cases from another two hospitals). Candidate factors included clinical, vascular, and 2D and 3D data. Combining the least absolute shrinkage and operator method, support vector machine, and probability calibration by isotonic regression, we constructed four predictive models: clinical, 2D, 3D, and combined models. Their discrimination and calibration were compared to identify the optimal model, with subgroup analysis performed.
    RESULTS: The 3D model showed better discrimination than did the 2D model (training: 0.719 vs. 0.691; validation: 0.730 vs. 0.622). The model combining clinical and 3D factors outperformed the clinical and 3D models (training: 0.802 vs. 0.735 vs. 0.719; validation: 0.816 vs. 0.723 vs. 0.730; all p < 0.050). Moreover, the combined model had the best calibration. The performance of the best model was not affected by the total bilirubin level, Child-Pugh score, ammonia level, or the indication for TIPS.
    CONCLUSIONS: 3D assessment of the liver and the spleen provided additional information to predict overt HE, improving the chance of TIPS for suitable patients. 3D assessment could also be used in similar studies related to cirrhosis.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    本文旨在提供一种创新的2D相空间模型,并评估其在对正常和癫痫患者的脑电图(EEG)信号进行分类方面的性能。本研究的主要贡献如下。(1)第一次,在脑电分析中,提出了一种基于2片玫瑰螺旋曲线(RSC)的新二维模型。(2)针对不同性质的信号,研究了模型的轨迹模式,包括常数,周期性,随机,和脑电图。(3)提出了一些量化轨迹模式的基准。(4)采取这些措施,支持向量机,朴素贝叶斯,AdaBoost,在癫痫脑电分类问题中使用K近邻来估计方法效率。波恩数据库,它考虑了健康的脑电信号,在癫痫发作的过程中,免检案件,被评估。结果表明,所提出的框架为识别健康受试者和癫痫发作活动的EEG提供了100%的正确率。此外,无癫痫发作的脑活动分类的准确率为96.7%.最后,所提出的RSC模型可适用于作为癫痫发作的计算机辅助诊断工具。
    This paper aimed to provide an innovative 2D phase space model and evaluate its performance in categorizing electroencephalogram (EEG) signals of normal and epileptic patients. The main contributions of the current study are as follows. (1) For the first time, it was proposed a new 2D model based on a 2-piece Rose Spiral Curve (RSC) in EEG analysis. (2) The trajectory patterns of the model were examined for signals of different natures, including constant, periodic, random, and EEG. (3) It was presented some benchmarks for quantifying the trajectory patterns. (4) Applying these measures, support vector machine, Naïve Bayes, AdaBoost, and K-nearest neighbor were used in the epileptic EEG classification problem to estimate the method efficiency. Bonn database, which takes account of EEG signals of healthy, in the course of an epileptic seizure occurrence, and seizure-free cases, was assessed. The results indicated that the proposed framework provided a correct rate of 100% for recognizing healthy subjects and the EEGs with seizure activity. Additionally, seizure-free brain activity was classified with an accuracy of 96.7%. To conclude, the proposed RSC model can be suitable for serving as a computer-aided diagnosis tool for epileptic seizures.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    It is well known that membrane reactors are inherently two-dimensional systems in which species concentrations vary as a consequence of both the reaction and permeation across the membrane, which occurs in the direction perpendicular to that of the main gas flow. Recently, an expression for an enhanced Sherwood number was developed to describe the hydrogen concentration gradients arising in methane steam-reforming membrane reactors as a consequence of the combined effect of hydrogen production, dispersion, and permeation. Here, the analysis is developed in further detail with the aim of (i) assessing the validity of the simplifying assumptions made when developing the 1D model and (ii) identifying the operating conditions under which it is possible to employ the 1D model with the enhanced Sherwood number.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    Atherosclerosis is a complex inflammatory pathology underpinning cardiovascular diseases (CVD), which are the leading cause of death worldwide. The interplay between vascular stromal cells and immune cells is fundamental to the progression and outcome of atherosclerotic disease, however, the majority of in vitro studies do not consider the implications of these interactions and predominantly use mono-culture approaches. Here we present a simple and robust methodology involving the co-culture of vascular endothelial (ECs) and smooth muscle cells (SMCs) alongside an inflammatory compartment, in our study containing THP-1 macrophages, for studying these complex interactions. Using this approach, we demonstrate that the interaction between vascular stromal and immune cells produces unique cellular phenotypes and soluble mediator profiles not observed in double-cell 2D cultures. Our results highlight the importance of cellular communication and support the growing idea that in vitro research must evolve from mono-culture systems to provide data more representative of the multi-cellular environment found in vivo. The methodology presented, in comparison with established approaches, has the advantage of being technically simple whilst enabling the isolation of pure populations of ECs, SMCs and immune cells directly from the co-culture without cell sorting. The approach described within would be applicable to those studying mechanisms of vascular inflammation, particularly in relation to understanding the impact cellular interaction has on the cumulative immune-vascular response to atherogenic or inflammatory stimuli.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

公众号