We study a logistic model-based activelearning procedure for binary classification problems, in which we adopt a batch subject selection strategy with a modified sequential experimental design method. Moreover, accom...
详细信息
We study a logistic model-based activelearning procedure for binary classification problems, in which we adopt a batch subject selection strategy with a modified sequential experimental design method. Moreover, accompanying the proposed subject selection scheme, we simultaneously conduct a greedy variable selection procedure such that we can update the classification model with all labeled training subjects. The proposed algorithm repeatedly performs both subject and variable selection steps until a prefixed stopping criterion is reached. Our numerical results show that the proposed procedure has competitive performance, with smaller training size and a more compact model compared with that of the classifier trained with all variables and a full data set. We also apply the proposed procedure to a well-known wave data set (Breiman et al., 1984) and a MAGIC gamma telescope data set to confirm the performance of our method, (C) 2018 Elsevier B.V. All rights reserved.
Evaluating the reliability of slopes with spatial variability is a challenging issue, especially when the failure probably of the target event is at a low level, because of unaffordable computational cost required in ...
详细信息
Evaluating the reliability of slopes with spatial variability is a challenging issue, especially when the failure probably of the target event is at a low level, because of unaffordable computational cost required in such cases. In this context, an adaptive surrogate model-based approach, namely activelearning-assisted bootstrap polynomial chaos expansion, is proposed to alleviate the above computational burden. The proposed approach extends the traditional polynomial chaos expansion by introducing the bootstrap resampling method so that it can deal with reliability issues smoothly and provide a feasible configuration environment to support the active learning algorithm. The computational efficiency can thus be greatly improved by adaptively searching for the most informative samples to train the surrogate model through iterative program. Two spatially varying soil slopes are studied to illustrate the validity of the activelearning-assisted bootstrap polynomial chaos expansion. The results show that the proposed approach has superior advantages in terms of efficiency and accuracy, and it is also suitable for handling problems with complex parameter configurations, including high dimensionality and cross-correlation. Besides, the proposed approach has potential in addressing geotechnical engineering problems with low probability levels.
In computer vision and pattern recognition applications, there are usually a vast number of unlabelled data whereas the labelled data are very limited. activelearning is a kind of method that selects the most represe...
详细信息
In computer vision and pattern recognition applications, there are usually a vast number of unlabelled data whereas the labelled data are very limited. activelearning is a kind of method that selects the most representative or informative examples for labelling and training;thus, the best prediction accuracy can be achieved. A novel active learning algorithm is proposed here based on one-versus-one strategy support vector machine (SVM) to solve multi-class image classification. A new uncertainty measure is proposed based on some binary SVM classifiers and some of the most uncertain examples are selected from SVM output. To ensure that the selected examples are diverse from each other, Gaussian kernel is adopted to measure the similarity between any two examples. From the previous selected examples, a batch of diverse and uncertain examples are selected by the dynamic programming method for labelling. The experimental results on two datasets demonstrate the effectiveness of the proposed algorithm.
Conventional ultra-high performance concrete (UHPC) has excellent development potential. However, a significant quantity of CO2 is produced throughout the cement-making process, which is in contrary to the current wor...
详细信息
Conventional ultra-high performance concrete (UHPC) has excellent development potential. However, a significant quantity of CO2 is produced throughout the cement-making process, which is in contrary to the current worldwide trend of lowering emissions and conserving energy, thus restricting the further advancement of UHPC. Considering climate change and sustainability concerns, cementless, eco-friendly, alkali-activated UHPC (AA-UHPC) materials have recently received considerable attention. Following the emergence of advanced prediction techniques aimed at reducing experimental tools and labor costs, this study provides a comparative study of different methods based on machine learning (ML) algorithms to propose an activelearning-based ML model (AL-Stacked ML) for predicting the compressive strength of AA-UHPC. A data-rich framework containing 284 experimental datasets and 18 input parameters was collected. A comprehensive evaluation of the significance of input features that may affect compressive strength of AA-UHPC was performed. Results confirm that AL-Stacked ML-3 with accuracy of 98.9% can be used for different general experimental specimens, which have been tested in this research. activelearning can improve the accuracy up to 4.1% and further enhance the Stacked ML models. In addition, graphical user interface (GUI) was introduced and validated by experimental tests to facilitate comparable prospective studies and predictions.
Monte Carlo simulation (MCS)-based calibrations can accurately determine probabilistic load and resistance factors (LRFs) needed in the limit state designs. However, most of the computing time and effort of the calibr...
详细信息
Monte Carlo simulation (MCS)-based calibrations can accurately determine probabilistic load and resistance factors (LRFs) needed in the limit state designs. However, most of the computing time and effort of the calibrations is for evaluating performance functions if they are defined implicitly, as in the case of slope stabilities. This study proposes a robust framework that combines the advantages of adaptive artificial neural networks (ANNs) in approximating implicit performance functions with an optimization process to establish the LRFs quickly and automatically. Furthermore, experiment data obtained in the preceding iterations of the optimizations are accumulated and reused in the subsequent trial. For illustration, three implicit problems, including a slope and two cases of breakwater foundation stability, are examined to demonstrate the efficiency and accuracy of the proposed procedure. The investigations show that the proposed framework can be accurately completed within 1 h instead of lasting for weeks of calculation when using basic MCSs. Remarkably, reusing experiment data helps decrease the necessary data by two-thirds compared to only using the adaptive ANN, facilitating a faster calibration process. Thus, this work contributes a practical method for calibrating LRFs needed in limit state designs of geotechnical engineering fields wherein limit state equations are defined in implicit fashions.
A wing is an important part of the aircraft to improve aerodynamic performance. The current study is focused on an adaptive surrogate algorithm for airfoil aerodynamic optimization, which is based on a multi-output Ga...
详细信息
A wing is an important part of the aircraft to improve aerodynamic performance. The current study is focused on an adaptive surrogate algorithm for airfoil aerodynamic optimization, which is based on a multi-output Gaussian process model. The conventional design method seriously relies on wind tunnel experiments and expensive computational simulations. The metamodels can significantly improve design efficiency and hence reduce the overall design costs. An active learning algorithm is proposed to improve the effectiveness of the multi-output Gaussian process model. The NSGA-II algorithm is adopted to obtain the optimal Pareto set with the optimization objectives of lift and drag coefficients for adaptive airfoil shapes. Besides, the Bezier curve and radial basis function are utilized in this study for airfoil mesh deformation. The results show that the airfoil shape can be obtained effectively by integrating the metamodel, active learning algorithm, and multi-objective optimization algorithm. The optimized results are of great engineering applications.
In spite of recent advancements in reliability analysis, high-dimensional and low-failure probability problems remain challenging because many samples and function calls are required for an accurate result. Function c...
详细信息
In spite of recent advancements in reliability analysis, high-dimensional and low-failure probability problems remain challenging because many samples and function calls are required for an accurate result. Function calls lead to a sharp increase in computational cost in terms of time. For this reason, an active learning algorithm is proposed using Kriging metamodel, where an unsupervised algorithm is used to select training samples from random samples for the first and second iterations. Then, the metamodel is improved iteratively by enriching the concerned domain with samples near the limit state function and samples obtained from a space-filling design. Hence, rapid convergence with the minimum number of function calls occurs using this active learning algorithm. An efficient stopping criterion has been developed to avoid premature or late-mature terminations of the metamodel and to regulate the accuracy of the failure probability estimations. The efficacy of this algorithm is examined using relative error, number of function calls, and coefficient of efficiency in five examples which are based on high-dimensional and low-failure probability with random and interval variables.
Due to the diverse and volatile nature of today's network attacks, it is difficult to achieve satisfactory results using a single detection method. This project plans to study the network intrusion detection algor...
详细信息
Due to the diverse and volatile nature of today's network attacks, it is difficult to achieve satisfactory results using a single detection method. This project plans to study the network intrusion detection algorithm based on Semi-Supervised learning and activelearning to improve its accuracy and effectively intercept various network attacks. First, network attack data is collected, attack characteristics are extracted, and Semi-Supervised learning method is used to cluster attack data. Secondly, by studying the clustering data, a network intrusion detection classifier based on BP neural network was constructed, and the construction process of the classifier was improved. On this basis, the effectiveness of the algorithm was verified through simulation experiments using standard datasets. The experimental results show that the combination rate of the optimized algorithm for network intrusion detection and neural network methods is over 95%, which can meet the actual accuracy requirements of network security protection. This is because the method proposed by the author combines semi supervised technology with BP neural network, which can effectively identify different types of network intrusion behavior, thereby reducing the missed detection rate and false alarm rate of network intrusion detection, and has significant advantages.
暂无评论