Multilayer perceptron

多层感知器
  • 文章类型: Journal Article
    以其高度的时空变异性为特征,降雨很难预测,尤其是在气候变化下。本研究提出了一种基于遗传算法(GA)优化的多层感知器(MLP)网络,粒子群优化(PSO),萤火虫算法(FFA)和遥相关模式指数-如北大西洋涛动(NAO),南方涛动(SOI)西地中海涛动(WeMO)和地中海涛动(MO)-模拟Sebaou河流域(阿尔及利亚北部)的每月降雨。之后,我们将最佳优化的MLP与Bat算法优化的极限学习机(Bat-ELM)的应用进行了比较。对各种输入组合的评估表明,NAO指数是提高建模精度的最有影响力的参数。结果表明,MLP-FFA模型在测试阶段优于MLP-GA和MLP-PSO。表示RMSE值等于33.36、30.50和29.92mm,分别。最佳MLP模型与Bat-ELM之间的比较表明,Bat-ELM在Sebaou河流域的降雨建模中具有高性能,在测试阶段,RMSE从29.92降至11.89mm,NSE值从0.902降至0.985。这项研究表明,将北大西洋振荡(NAO)作为预测器提高了元启发式算法优化的人工智能系统的准确性,特别是Bat-ELM,用于降雨建模任务,例如填充降雨时间序列的缺失数据。
    Characterized by their high spatiotemporal variability, rainfalls are difficult to predict, especially under climate change. This study proposes a multilayer perceptron (MLP) network optimized by Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Firefly Algorithm (FFA), and Teleconnection Pattern Indices - such as North Atlantic Oscillation (NAO), Southern Oscillations (SOI), Western Mediterranean Oscillation (WeMO), and Mediterranean Oscillation (MO) - to model monthly rainfalls at the Sebaou River basin (Northern Algeria). Afterward, we compared the best-optimized MLP to the application of the Extreme Learning Machine optimized by the Bat algorithm (Bat-ELM). Assessment of the various input combinations revealed that the NAO index was the most influential parameter in improving the modeling accuracy. The results indicated that the MLP-FFA model was superior to MLP-GA and MLP-PSO for the testing phase, presenting RMSE values equal to 33.36, 30.50, and 29.92 mm, respectively. The comparison between the best MLP model and Bat-ELM revealed the high performance of Bat-ELM for rainfall modeling at the Sebaou River basin, with RMSE reducing from 29.92 to 11.89 mm and NSE value from 0.902 to 0.985 during the testing phase. This study shows that incorporating the North Atlantic Oscillation (NAO) as a predictor improved the accuracy of artificial intelligence systems optimized by metaheuristic algorithms, specifically Bat-ELM, for rainfall modeling tasks such as filling in missing data of rainfall time series.
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  • 文章类型: Journal Article
    使用能够预测光伏(PV)能源生产的模型对于确保该能源与传统配电网的最佳集成至关重要。长短期记忆网络(LSTM)通常用于此目的,但它们的使用可能不是更好的选择,因为它们的计算复杂性很大,推理和训练时间较慢。因此,在这项工作中,我们寻求评估神经网络MLP(多层感知器)的使用,循环神经网络(RNN),和LSTMs,用于预测5min的光伏能源产量。预测的每次迭代都使用从光伏系统收集的最后120分钟的数据(功率,辐照,和PV电池温度),从2019年到2022年年中在Maceió(巴西)测量。此外,使用贝叶斯超参数优化来获得每个模型的最佳结果,并在平等的基础上进行比较。结果表明,MLP表现令人满意,需要更少的时间来训练和预测,表明在特定情况下处理非常短期的预测时,它们可能是一个更好的选择,例如,在计算资源很少的系统中。
    The use of models capable of forecasting the production of photovoltaic (PV) energy is essential to guarantee the best possible integration of this energy source into traditional distribution grids. Long Short-Term Memory networks (LSTMs) are commonly used for this purpose, but their use may not be the better option due to their great computational complexity and slower inference and training time. Thus, in this work, we seek to evaluate the use of neural networks MLPs (Multilayer Perceptron), Recurrent Neural Networks (RNNs), and LSTMs, for the forecast of 5 min of photovoltaic energy production. Each iteration of the predictions uses the last 120 min of data collected from the PV system (power, irradiation, and PV cell temperature), measured from 2019 to mid-2022 in Maceió (Brazil). In addition, Bayesian hyperparameters optimization was used to obtain the best of each model and compare them on an equal footing. Results showed that the MLP performs satisfactorily, requiring much less time to train and forecast, indicating that they can be a better option when dealing with a very short-term forecast in specific contexts, for example, in systems with little computational resources.
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  • 文章类型: Journal Article
    揭示大脑各种结构和功能模式之间的关联可以产生有关健康和无序大脑的高度信息的结果。使用神经成像数据的研究最近开始利用各种功能和解剖领域内的信息(即,大脑网络组)。然而,大多数全脑方法都假设整个大脑中相互作用的复杂性相似。在这里,我们研究了大脑网络之间的相互作用捕获不同数量的复杂性的假设,并且我们可以通过基于可用的训练数据改变模型子空间结构的复杂性来更好地捕获这些信息。要做到这一点,我们采用基于贝叶斯优化的框架,称为树parzen估计器(TPE)来识别,利用和分析从大脑的功能磁共振成像(fMRI)子域中提取的时间信息编码的信息的变化模式。在精神分裂症分类任务上使用重复的交叉验证程序,我们证明有证据表明,特定功能子域之间的相互作用通过更复杂的模型架构更好地表征,而其他功能子域需要的较不复杂的模型架构对分类和理解大脑的功能相互作用做出最佳贡献.我们表明,已知与精神分裂症有关的功能子域需要更复杂的体系结构,以最佳地解开有关该疾病的歧视性信息。我们的研究指出了适应性的必要性,分层学习框架,以不同的方式满足不同子域的特征,不仅为了更好的预测,而且还能够识别预测感兴趣结果的特征。
    Revealing associations among various structural and functional patterns of the brain can yield highly informative results about the healthy and disordered brain. Studies using neuroimaging data have more recently begun to utilize the information within as well as across various functional and anatomical domains (i.e., groups of brain networks). However, most whole-brain approaches assume similar complexity of interactions throughout the brain. Here we investigate the hypothesis that interactions between brain networks capture varying amounts of complexity, and that we can better capture this information by varying the complexity of the model subspace structure based on available training data. To do this, we employ a Bayesian optimization-based framework known as the Tree Parzen Estimator (TPE) to identify, exploit and analyze patterns of variation in the information encoded by temporal information extracted from functional magnetic resonance imaging (fMRI) subdomains of the brain. Using a repeated cross-validation procedure on a schizophrenia classification task, we demonstrate evidence that interactions between specific functional subdomains are better characterized by more sophisticated model architectures compared to less complicated ones required by the others for optimally contributing towards classification and understanding the brain\'s functional interactions. We show that functional subdomains known to be involved in schizophrenia require more complex architectures to optimally unravel discriminatory information about the disorder. Our study points to the need for adaptive, hierarchical learning frameworks that cater differently to the features from different subdomains, not only for a better prediction but also for enabling the identification of features predicting the outcome of interest.
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  • 文章类型: Journal Article
    用于溶液的埃索美拉唑粉末生产的关键步骤是填充过程和冻干之间的一段时间。所有的小瓶,部分封闭,完全受到环境影响。过度的不稳定性反映在由氧气的影响引起的pH值变化中。为了提供pH控制,从而影响药物的稳定性,埃索美拉唑批次,以同样的方式生产,在20°C和-30°C的温度下在部分封闭的小瓶中保持3小时,之后,将它们冻干并长期稳定储存36个月。本研究的目的是应用一种深度学习算法来预测埃索美拉唑的稳定性,并确定最终冻干产品的重组溶液的pH极限,以确保在36个月的储存期内的产品质量。多层感知器(MLP)作为一种深度学习工具,有四层,被使用。埃索美拉唑溶液的pH值和储存时间(月)为网络输入,而埃索美拉唑测定和四种主要杂质是网络的输出。为了在整个保质期内保持所有相关物质和埃索美拉唑测定符合规格,重构的成品的pH值应设定在10.4-10.6的范围内。
    A critical step in the production of Esomeprazole powder for solution is a period between the filling process and lyophilization, where all vials, partially closed, are completely exposed to environmental influences. Excessive instability reflects in pH value variations caused by oxygen\'s impact. In order to provide pH control, which consequently affects drug stability, Esomeprazole batches, produced in the same way, were kept in partially closed vials for 3 h at temperatures of 20 °C and -30 °C, after which they were lyophilized and stored for long-term stability for 36 months. The aim of the presented study was to apply a deep-learning algorithm for the prediction of the Esomeprazole stability profile and to determine the pH limit for the reconstituted solution of the final freeze-dried product that would assure a quality product profile over a storage period of 36 months. Multilayer perceptron (MLP) as a deep learning tool, with four layers, was used. The pH value of Esomeprazole solution and time of storage (months) were inputs for the network, while Esomeprazole assay and four main impurities were outputs of the network. In order to keep all related substances and Esomeprazole assay in accordance with specifications for the whole shelf life, the pH value for the reconstituted finish product should be set in the range of 10.4-10.6.
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  • 文章类型: Journal Article
    背景:优化体细胞胚发生方案可以被认为是成功的基因转化研究的第一步。然而,由于该过程的成本和耗时以及复杂性,通常难以实现优化的胚胎发生方案。因此,有必要使用一种新的计算方法,例如用于此目的的机器学习算法。在本研究中,两种机器学习算法,包括作为人工神经网络(ANN)的多层感知器(MLP)和支持向量回归(SVR),被用来模拟菊花的体细胞胚胎发生,作为一个案例研究,并比较它们的预测精度。
    结果:结果表明,SVR(R2>0.92)比MLP(R2>0.82)具有更好的性能准确性。此外,非支配排序遗传算法-II(NSGA-II)也用于体细胞胚胎发生的优化,结果表明,最高的胚胎发生率(99.09%)和每个外植体的最大体细胞胚胎数(56.24)可以从含有9.10μM2,4-二氯苯氧基乙酸(2,4-D)的培养基中获得,4.70μM激动素(KIN),和18.73μM硝普钠(SNP)。根据我们的结果,SVR-NSGA-II能够准确优化菊花的体细胞胚胎发生。
    结论:SVR-NSGA-II可以在未来的植物组织培养研究中用作可靠和适用的计算方法。
    BACKGROUND: Optimizing the somatic embryogenesis protocol can be considered as the first and foremost step in successful gene transformation studies. However, it is usually difficult to achieve an optimized embryogenesis protocol due to the cost and time-consuming as well as the complexity of this process. Therefore, it is necessary to use a novel computational approach, such as machine learning algorithms for this aim. In the present study, two machine learning algorithms, including Multilayer Perceptron (MLP) as an artificial neural network (ANN) and support vector regression (SVR), were employed to model somatic embryogenesis of chrysanthemum, as a case study, and compare their prediction accuracy.
    RESULTS: The results showed that SVR (R2 > 0.92) had better performance accuracy than MLP (R2 > 0.82). Moreover, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was also applied for the optimization of the somatic embryogenesis and the results showed that the highest embryogenesis rate (99.09%) and the maximum number of somatic embryos per explant (56.24) can be obtained from a medium containing 9.10 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 4.70 μM kinetin (KIN), and 18.73 μM sodium nitroprusside (SNP). According to our results, SVR-NSGA-II was able to optimize the chrysanthemum\'s somatic embryogenesis accurately.
    CONCLUSIONS: SVR-NSGA-II can be employed as a reliable and applicable computational methodology in future plant tissue culture studies.
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  • 文章类型: Journal Article
    Over the past few decades, geometric morphometric methods have become increasingly popular and powerful tools to describe morphological data while over the same period artificial neural networks have had a similar rise in the classification of specimens to preconceived groups. However, there has been little research into how well these two systems operate together, particularly in comparison to preexisting techniques. In this study, geometric morphometric data and multilayer perceptrons, a style of artificial neural network, were used to classify shark teeth from the genus Carcharhinus to species. Three datasets of varying size and species differences were used. We compared the performance of this combination with geometric morphometric data in a linear discriminate function analysis, linear measurements in a linear discriminate function analysis, and a preexisting methodology from the literature that incorporates linear measurements and a two-layered discriminate function analysis. Across datasets, geometric morphometric data in a multilayer perceptron tended to yield modest accuracies but accuracies that varied less across species whereas other methods were able to achieve higher accuracies in some species at the expense of lower accuracies in others. Further, the performance of the two-layered discriminate function analysis illustrates that constraining what material is classified can increase the accuracy of a method. Based on this tradeoff, the best methodology will then depend on the scope of the study and the amount of material available. J. Morphol. 278:131-141, 2017. ©© 2016 Wiley Periodicals,Inc.
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  • 文章类型: Journal Article
    Prioritization of compounds using inverse docking approach is limited owing to potential drawbacks in its scoring functions. Classically, molecules ranked by best or lowest binding energies and clustering methods have been considered as probable hits. Mining probable hits from an inverse docking approach is very complicated given the closely related protein targets and the chemically similar ligand data set. To overcome this problem, we present here a computational approach using receptor-centric and ligand-centric methods to infer the reliability of the inverse docking approach and to recognize probable hits. This knowledge-driven approach takes advantage of experimentally identified inhibitors against a particular protein target of interest to delineate shape and molecular field properties and use a multilayer perceptron model to predict the biological activity of the test molecules. The approach was validated using flavone derivatives possessing inhibitory activities against principal antimalarial molecular targets of fatty acid biosynthetic pathway, FabG, FabI and FabZ, respectively. We propose that probable hits can be retrieved by comparing the rank list of docking, quantitative-structure activity relationship and multilayer perceptron models.
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