Genetic Algorithms

遗传算法
  • 文章类型: Journal Article
    背景:干预计划者使用逻辑模型来设计基于证据的健康行为干预措施。捕获健康行为复杂性的逻辑模型需要额外的计算技术来告知有关干预措施设计的决策。
    目的:使用来自实际干预的经验数据,本文演示了机器学习如何与模糊认知图一起使用,以帮助设计健康行为改变干预措施。
    方法:对来自实际干预研究的纵向数据应用改进的RealCoded遗传算法。该数据集包含有关荷兰257名成年人中15种水果摄入量决定因素的信息。使用模糊认知图分析了领域专家设计的两种假设干预方案的效果。
    结果:模拟表明,指定的假设干预措施对水果摄入量的影响很小。结果与本文使用的经验证据一致。
    结论:机器学习与模糊认知图一起可以帮助构建具有复杂逻辑模型的健康行为干预措施。对假设场景的测试可能有助于干预人员对干预组件进行微调,从而提高其潜在有效性。
    Intervention planners use logic models to design evidence-based health behavior interventions. Logic models that capture the complexity of health behavior necessitate additional computational techniques to inform decisions with respect to the design of interventions.
    Using empirical data from a real intervention, the present paper demonstrates how machine learning can be used together with fuzzy cognitive maps to assist in designing health behavior change interventions.
    A modified Real Coded Genetic algorithm was applied on longitudinal data from a real intervention study. The dataset contained information about 15 determinants of fruit intake among 257 adults in the Netherlands. Fuzzy cognitive maps were used to analyze the effect of two hypothetical intervention scenarios designed by domain experts.
    Simulations showed that the specified hypothetical interventions would have small impact on fruit intake. The results are consistent with the empirical evidence used in this paper.
    Machine learning together with fuzzy cognitive maps can assist in building health behavior interventions with complex logic models. The testing of hypothetical scenarios may help interventionists finetune the intervention components thus increasing their potential effectiveness.
    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
    提出了一种结合逆时偏移(RTM)和遗传算法(GA)的新重建方法,用于解决与腔内剪切波弹性成像相关的反问题。经尿道识别经直肠高强度聚焦超声(HIFU)治疗前列腺癌产生的第一个热损伤,对组合重建方法进行了初步的仿真测试。通过比较几种互相关技术的重建图像来优化RTM方法,包括一个新提议的,以及在概念性经尿道探头的发射器和接收器的数量和布置方面的不同设备配置。对于新提出的互相关方法和具有3个发射器和32个接收器的设备配置,获得了最佳结果。RTM重建没有完全勾勒出HIFU损伤的形状,然而,按照联合方法的计划,RTM图像中具有高度相关性的区域用于缩小基于GA技术的搜索空间。设置基于GA的技术以找到HIFU病变的位置以及由于热损伤引起的刚度和粘度的增加。总的来说,组合方法在重建值中实现了较低的误差水平,在较短的计算时间内,与单独的基于GA的技术相比。HIFU病变位置误差最低,然后是热处理组织和未处理的正常组织之间的硬度对比度。粘度的同源比获得了较高的误差水平。考虑到要重建的各种场景并使用实验数据进行进一步调查,以充分评估组合方法的可行性。
    A new reconstruction approach that combines Reverse Time Migration (RTM) and Genetic Algorithms (GAs) is proposed for solving the inverse problem associated with transluminal shear wave elastography. The transurethral identification of the first thermal lesion generated by transrectal High Intensity Focused Ultrasound (HIFU) for the treatment of prostate cancer, was used to preliminarily test in silico the combined reconstruction method. The RTM method was optimised by comparing reconstruction images from several cross-correlation techniques, including a new proposed one, and different device configurations in terms of the number and arrangement of emitters and receivers of the conceptual transurethral probe. The best results were obtained for the new proposed cross-correlation method and a device configuration with 3 emitters and 32 receivers. The RTM reconstructions did not completely contour the shape of the HIFU lesion, however, as planned for the combined approach, the areas in the RTM images with high level of correlation were used to narrow down the search space in the GA-based technique. The GA-based technique was set to find the location of the HIFU lesion and the increment in stiffness and viscosity due to thermal damage. Overall, the combined approach achieves lower level of error in the reconstructed values, and in a shorter computational time, compared to the GA-based technique alone. The lowest errors were accomplished for the location of HIFU lesion, followed by the contrast ratio of stiffness between thermally treated tissue and non-treated normal tissue. The homologous ratio of viscosity obtained higher level of error. Further investigation considering diverse scenarios to be reconstructed and with experimental data is required to fully evaluate the feasibility of the combined approach.
    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
    地下水脆弱性评估如今已发展成为适当保护和管理地下水的重要工具,而DRASTIC方法是应用最广泛的漏洞评估方法之一。然而,DRASTIC方法的高度不确定性主要与分配参数评级和权重的主观性有关,这促使许多研究人员应用各种方法来提高效率。在这种情况下,在本研究中,实施了不同的技术,目的是修改DRASTIC框架,从而提高其在Bouficha含水层中地下水脆弱性评估的性能,突尼斯。在第一阶段,土地利用类型(L)作为典型DRASTIC框架中的附加参数,因此考虑到人为活动对地下水脆弱性的影响。随后,通过应用统计方法(DRASTIC-L-SA)和遗传算法(GA)(DRASTIC-L-GA)对已开发的DRASTIC-L框架的评级和加权系统进行了修改,试图研究和比较线性和非线性修改.为了评估各种漏洞框架,脆弱性值与硝酸盐浓度之间的相关性,表示为斯皮尔曼等级相关系数(ρ)和相关指数(CI),被检查过。结果表明,通过应用完全基于GA的优化程序开发的DRASTIC-L-GA框架在使用的性能指标方面提供了最高值,使其最适合研究区域。此外,当采用典型的DRASTIC框架而不是经过修改的框架时,发现所研究的含水层不太容易受到污染,得出的结论是,前者大大低估了研究区域的污染潜力。
    Groundwater vulnerability assessment has nowadays evolved into an essential tool towards proper groundwater protection and management, while the DRASTIC method is included among the most widely applied vulnerability assessment methods. However, the high uncertainty of the DRASTIC method mainly associated with the subjectivity in assigning parameters ratings and weights has driven many researchers to apply various methods for improving its efficiency. In this context, in the present study, different techniques were implemented with the aim of modifying the DRASTIC framework and thus enhancing its performance for groundwater vulnerability assessment in the Bouficha aquifer, Tunisia. In a first stage, the land use type (L) was incorporated as an additional parameter in the typical DRASTIC framework, thus taking into consideration the impact of anthropogenic activities on groundwater vulnerability. Subsequently, the rating and weighting systems of the developed DRASTIC-L framework were modified through the application of statistical methods (DRASTIC-L-SA) and genetic algorithms (GA) (DRASTIC-L-GA) in an attempt to investigate and compare both linear and nonlinear modifications. To evaluate the various vulnerability frameworks, correlation between vulnerability values and nitrate concentrations, expressed as Spearman\'s rank correlation coefficient (ρ) and Correlation Index (CI), was examined. The results revealed that the DRASTIC-L-GA framework developed by applying a fully GA-based optimization procedure provided the highest values in terms of the performance metrics used, making it the most suitable for the study area. In addition, the aquifer under study was found to be less vulnerable to pollution when employing the typical DRASTIC framework instead of the modified ones, leading to the conclusion that the former substantially underestimates pollution potential in the study area.
    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
    厌氧消化(AnD)是一种将有机废物转化为沼气等能源的过程,在废物处理中引入可持续性和循环经济。AnD是一个复杂的过程,因为涉及多个参数,当废物来自不同类型的发电机时,其复杂性就会增加。在这种情况下,实现良好性能的一个关键点是优化方法。目前,已经开发了许多工具来优化单个AnD工厂。然而,对AND工厂和多个废物发生器网络的研究,都在不同的位置,仍未探索。这种新颖的方法需要使用具有处理高度复杂的组合问题的能力的优化方法。本文提出并比较了三种进化算法的使用:蚁群优化(ACO),遗传算法(GA)和粒子群优化(PSO),特别适合这种类型的应用。算法成功地解决了这个问题,使用包括与质量和物流相关的术语的目标函数。它们在加泰罗尼亚(西班牙)的真实案例研究中的应用表明了它们对AnD设施的有用性(ACO和GA可实现最大的沼气生产,而PSO可实现更安全的操作条件)。
    Anaerobic digestion (AnD) is a process that allows the conversion of organic waste into a source of energy such as biogas, introducing sustainability and circular economy in waste treatment. AnD is an intricate process because of multiple parameters involved, and its complexity increases when the wastes are from different types of generators. In this case, a key point to achieve good performance is optimisation methods. Currently, many tools have been developed to optimise a single AnD plant. However, the study of a network of AnD plants and multiple waste generators, all in different locations, remains unexplored. This novel approach requires the use of optimisation methodologies with the capacity to deal with a highly complex combinatorial problem. This paper proposes and compares the use of three evolutionary algorithms: ant colony optimisation (ACO), genetic algorithm (GA) and particle swarm optimisation (PSO), which are especially suited for this type of application. The algorithms successfully solve the problem, using an objective function that includes terms related to quality and logistics. Their application to a real case study in Catalonia (Spain) shows their usefulness (ACO and GA to achieve maximum biogas production and PSO for safer operation conditions) for AnD facilities.
    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
    优化空间网络中的全球连通性,通过重新布线或添加边,可以增加信息流并提高网络对故障的恢复能力。然而,对于具有固定边缘的系统,重新布线是不可行的,并且优化全局连接可能不会导致需要的系统中的最佳局部连接。我们描述了本地网络连接优化问题,将昂贵的边缘添加到具有已建立和固定边缘网络的系统中,以增加与特定位置的连接性,例如在运输和电信系统中。该问题的解决方案使网络中与焦点节点的给定距离内的节点数量最大化,同时使附加连接的数量和长度最小化。我们比较了几种应用于随机网络的启发式方法,包括两个新颖的平面随机网络,可用于空间网络模拟研究,一个真实的运输案例研究,和一组真实世界的社交网络数据。跨网络类型,观察到节点特征和最佳连接之间存在显著差异。搜索最佳解决方案的特征以及计算成本凸显了规定有效启发式方法的必要性。我们提供了一种新的遗传算法,优于现有技术。我们描述了这种启发式方法如何应用于其他组合和动态问题。
    Optimizing global connectivity in spatial networks, either through rewiring or adding edges, can increase the flow of information and increase the resilience of the network to failures. Yet, rewiring is not feasible for systems with fixed edges and optimizing global connectivity may not result in optimal local connectivity in systems where that is wanted. We describe the local network connectivity optimization problem, where costly edges are added to a systems with an established and fixed edge network to increase connectivity to a specific location, such as in transportation and telecommunication systems. Solutions to this problem maximize the number of nodes within a given distance to a focal node in the network while they minimize the number and length of additional connections. We compare several heuristics applied to random networks, including two novel planar random networks that are useful for spatial network simulation research, a real-world transportation case study, and a set of real-world social network data. Across network types, significant variation between nodal characteristics and the optimal connections was observed. The characteristics along with the computational costs of the search for optimal solutions highlights the need of prescribing effective heuristics. We offer a novel formulation of the genetic algorithm, which outperforms existing techniques. We describe how this heuristic can be applied to other combinatorial and dynamic problems.
    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
    背景:多酚是中国红枣中最重要的植物化学物质,因为它们具有许多潜在的健康益处,例如避免癌症,降低冠状动脉疾病的风险,利尿活动,心肌兴奋剂,冠状动脉扩张器和肌肉松弛剂。
    目的:利用近红外(NIR)和中红外(MIR)光谱数据融合方法对中国红枣中的多酚进行定量。
    方法:共使用80个中国枣样品从NIR和MIR光谱中获取数据。利用协同区间偏最小二乘(Si-PLS)算法提取有效光谱区间作为NIR-MIR融合模型的输入变量。采用遗传算法构建了基于NIR-MIR融合的模型。使用校准(R2)和预测(R2)的相关系数评估开发的模型的性能,预测均方根误差(RMSEP),偏差和残差预测偏差(RPD)。
    结果:基于GA的数据融合模型优于NIR和MIR构建模型。最佳GA融合模型的R2=0.9621,r2=0.9451,RPD=2.44,校准集偏差=0.004,预测集偏差=0.061,仅计算15个变量。
    结论:这些发现表明,NIR和MIR的整合对于预测中国枣中总多酚含量是可能的。
    BACKGROUND: Polyphenols are the foremost measure of phytochemicals in Chinese dates due to their many potential health benefits such as averting cancers, reducing the risk of coronary artery disease, diuretic activity, myocardial stimulant, coronary dilator and muscle relaxant.
    OBJECTIVE: To quantitate the polyphenols in Chinese dates using a data fusion approach with near-infrared (NIR) and mid-infrared (MIR) spectroscopy.
    METHODS: A total of 80 Chinese dates samples were used for data acquisition from both NIR and MIR spectroscopy. The efficient spectral intervals were extracted by the synergy interval partial least square (Si-PLS) algorithm as input variables for NIR-MIR fusion model. A genetic algorithm (GA) was used to construct the model based on NIR-MIR fusion. The performance of the developed models was evaluated using correlation coefficients of calibration (R2 ) and prediction (r2 ), root mean square error of prediction (RMSEP), bias and residual prediction deviation (RPD).
    RESULTS: The data fusion model based on the GA was superior compared to NIR and MIR build model. The optimal GA-fusion model yielded R2  = 0.9621, r2  = 0.9451, RPD = 2.44, calibration set bias = 0.004 and prediction set bias = 0.061, computing only 15 variables.
    CONCLUSIONS: These findings reveal that integration of NIR and MIR is possible for the prediction of total polyphenol content in Chinese dates.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • DOI:
    文章类型: Journal Article
    17β-HSD3酶在前列腺癌的治疗中起着关键作用,并且可以使用小的抑制剂来有效地靶向它。在本研究中,多元线性回归(MLR),和支持向量机(SVM)方法用于解释某些17β-HSD3抑制剂的抑制活性的化学结构功能。通过各种类型的分子描述符描述化学结构信息,并应用遗传算法(GA)将抑制途径的复杂性降低到一些相关的分子描述符。非线性方法(GA-SVM)在内部和外部预测精度方面均优于线性方法(GA-MLR)。SVM模型,具有很高的统计学意义(R2train=0.938;R2test=0.870),已发现可用于估计17β-HSD3抑制剂的抑制活性。通过留一交叉验证和几种化合物作为外部测试集,对模型进行了严格验证。此外,通过考虑修正的R2和一致相关系数值,检验了所提模型的外部预测能力,Golbraikh和Tropsha可接受的模型标准,和来自外部数据集的额外评估集。使用Williams图仔细定义了线性模型的适用性域。此外,应用基于欧几里得的适用性域来定义评估集和训练集的化学结构多样性。
    The 17β-HSD3 enzyme plays a key role in treatment of prostate cancer and small inhibitors can be used to efficiently target it. In the present study, the multiple linear regression (MLR), and support vector machine (SVM) methods were used to interpret the chemical structural functionality against the inhibition activity of some 17β-HSD3inhibitors. Chemical structural information were described through various types of molecular descriptors and genetic algorithm (GA) was applied to decrease the complexity of inhibition pathway to a few relevant molecular descriptors. Non-linear method (GA-SVM) showed to be better than the linear (GA-MLR) method in terms of the internal and the external prediction accuracy. The SVM model, with high statistical significance (R2train = 0.938; R2test = 0.870), was found to be useful for estimating the inhibition activity of 17β-HSD3 inhibitors. The models were validated rigorously through leave-one-out cross-validation and several compounds as external test set. Furthermore, the external predictive power of the proposed model was examined by considering modified R2 and concordance correlation coefficient values, Golbraikh and Tropsha acceptable model criteria\'s, and an extra evaluation set from an external data set. Applicability domain of the linear model was carefully defined using Williams plot. Moreover, Euclidean based applicability domain was applied to define the chemical structural diversity of the evaluation set and training set.
    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
    There is an increased l-glutaminase market worldwide due to its relevant industrial applications. Salt tolerance l-glutaminases play a vital role in the increase of flavor of different types of foods like soya sauce and tofu. This chapter is presenting the economically viable l-glutaminases production in solid-state fermentation (SSF) by Aspergillus flavus MTCC 9972 as a case study. The enzyme production was improved following a three step optimization process. Initially mixture design (MD) (augmented simplex lattice design) was employed to optimize the solid substrate mixture. Such solid substrate mixture consisted of 59:41 of wheat bran and Bengal gram husk has given higher amounts of l-glutaminase. Glucose and l-glutamine were screened as a finest additional carbon and nitrogen sources for l-glutaminase production with help of Plackett-Burman Design (PBD). l-Glutamine also acting as a nitrogen source as well as inducer for secretion of l-glutaminase from A. flavus MTCC 9972. In the final step of optimization various environmental and nutritive parameters such as pH, temperature, moisture content, inoculum concentration, glucose, and l-glutamine levels were optimized through the use of hybrid feed forward neural networks (FFNNs) and genetic algorithm (GA). Through sequential optimization methods MD-PBD-FFNN-GA, the l-glutaminase production in SSF could be improved by 2.7-fold (453-1690U/g).
    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
    Quantitative structure-activity relationship (QSAR) study has been employed for predicting the inhibitory activities of the Hepatitis C virus (HCV) NS5B polymerase inhibitors . A data set consisted of 72 compounds was selected, and then different types of molecular descriptors were calculated. The whole data set was split into a training set (80 % of the dataset) and a test set (20 % of the dataset) using principle component analysis. The stepwise (SW) and the genetic algorithm (GA) techniques were used as variable selection tools. Multiple linear regression method was then used to linearly correlate the selected descriptors with inhibitory activities. Several validation technique including leave-one-out and leave-group-out cross-validation, Y-randomization method were used to evaluate the internal capability of the derived models. The external prediction ability of the derived models was further analyzed using modified r(2), concordance correlation coefficient values and Golbraikh and Tropsha acceptable model criteria\'s. Based on the derived results (GA-MLR), some new insights toward molecular structural requirements for obtaining better inhibitory activity were obtained.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    Bruton\'s tyrosine kinase (BTK) plays a crucial role in B-cell activation and development, and has emerged as a new molecular target for the treatment of autoimmune diseases and B-cell malignancies. In this study, two- and three-dimensional quantitative structure-activity relationship (2D and 3D-QSAR) analyses were performed on a series of pyridine and pyrimidine-based BTK inhibitors by means of genetic algorithm optimized multivariate adaptive regression spline (GA-MARS) and comparative molecular similarity index analysis (CoMSIA) methods. Here, we propose a modified MARS algorithm to develop 2D-QSAR models. The top ranked models showed satisfactory statistical results (2D-QSAR: Q(2) = 0.884, r(2) = 0.929, r(2)pred = 0.878; 3D-QSAR: q(2) = 0.616, r(2) = 0.987, r(2)pred = 0.905). Key descriptors selected by 2D-QSAR were in good agreement with the conclusions of 3D-QSAR, and the 3D-CoMSIA contour maps facilitated interpretation of the structure-activity relationship. A new molecular database was generated by molecular fragment replacement (MFR) and further evaluated with GA-MARS and CoMSIA prediction. Twenty-five pyridine and pyrimidine derivatives as novel potential BTK inhibitors were finally selected for further study. These results also demonstrated that our method can be a very efficient tool for the discovery of novel potent BTK inhibitors.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

公众号