The problems of asymmetry in information features and redundant features in datasets, and the asymmetry of network traffic distribution in the field of network intrusion detection, have been identified as a cause of low accuracy and poor generalization of traditional machine learning detection methods in intrusion detection systems (IDSs). In response, a network intrusion detection method based on the integration of bootstrap aggregating (bagging) is proposed. The extreme random tree (ERT) algorithm was employed to calculate the weights of each feature, determine the feature subsets of different machine learning models, then randomly sample the training samples based on the bootstrap sampling method, and integrated classification and regression trees (CART), support vector machine (SVM), and k-nearest neighbor (KNN) as the base estimators of bagging. A comparison of integration methods revealed that the KNN-Bagging integration model exhibited optimal performance. Subsequently, the Bayesian optimization (BO) algorithm was employed for hyper-parameter tuning of the base estimators’ KNN. Finally, the base estimators were integrated through a hard voting approach. The proposed BO-KNN-Bagging model was evaluated on the NSL-KDD dataset, achieving an accuracy of 82.48%. This result was superior to those obtained by traditional machine learning algorithms and demonstrated enhanced performance compared with other methods.

To solve the problem of the low segmentation accuracy of lung nodule CT images using U-Net, an improved method for segmentation of lung nodules by U-Net was proposed. Initially, the dense network connection and sawtooth expanded convolution design was added to the feature extraction part, and a local residual design was adopted in the upsampling process. Finally, the effectiveness of the proposed algorithm was evaluated using the LIDC-IDRI lung nodule public dataset. The results showed that the improved algorithm had 7.03%, 14.05%, and 10.43% higher performance than the U-Net segmentation algorithm under the three loss functions of DC, MIOU, and SE, and the accuracy was 2.45% higher compared with that of U-Net. Thus, the proposed method had an effective network structure.

The optimization of drug properties in the process of cancer drug development is very important to save research and development time and cost. In order to make the anti-breast cancer drug candidates with good biological activity, this paper collected 1974 compounds, firstly, the top 20 molecular descriptors that have the most influence on biological activity were screened by using XGBoost-based data feature selection; secondly, on this basis, take pIC50 values as feature data and use a variety of machine learning algorithms to compare, soas to select a most suitable algorithm to predict the IC50 and pIC50 values. It is preliminarily found that the effects of Random Forest, XGBoost and Gradient-enhanced algorithms are good and have little difference, and the Support vector machine is the worst. Then, using the Semi-automatic parameter adjustment method to adjust the parameters of Random Forest, XGBoost and Gradient-enhanced algorithms to find the optimal parameters. It is found that the Random Forest algorithm has high accuracy and excellent anti over fitting, and the algorithm is stable. Its prediction accuracy is 0.745. Finally, the accuracy of the results is verified by training the model with the preliminarily selected data, which provides an innovative solution for the optimization of the properties of anti- breast cancer drugs, and can provide better support for the early research and development of anti-breast cancer drugs.