关键词： Satellites   Telemetry   Space vehicles   Recurrent neural networks   Monitoring   Data mining   Machine learning  

摘要： Spacecrafts are critical systems that have to survive space environment effects. Due to its complexity, these types of systems are designed in away to mitigate errors and maneuver the critical situations. Spacecraft delivers to the ground operator an abundance data related to system status telemetry;the telemetry parameters are monitored to indicate spacecraft performance. Recently, researchers proposed using Machine Learning (ML)/Telemetry Mining (TM) techniques for telemetry parameters forecasting. Telemetry processing facilitates the data visualization to enable operators understanding the behavior of the satellite in order to reduce failure risks. In this paper, we introduce a comparison between the different machine learning techniques that can be applied for low earth orbit satellite telemetry mining. The techniques are evaluated on the bases of calculating the prediction accuracy using mean error and correlation estimation. We used telemetry data received from Egyptsat-1 satellite including parameters such as battery temperature, power bus voltage and load current. The research summarizes the performance of processing telemetry data using autoregressive integrated moving average (ARIMA), Multilayer Perceptron (MLP), Recurrent Neural Network (RNN), Long Short-Term Memory Recurrent Neural Network (LSTM RNN), Deep Long Short-Term Memory Recurrent Neural Networks (DLSTM RNNs), Gated Recurrent Unit Recurrent Neural Network (GRU RNN), and Deep Gated Recurrent Unit Recurrent Neural Networks (DGRU RNNs).

关键词： accretion, accretion discs   methods: data analysis   methods: statistical   astronomical data bases: miscellaneous   stars: evolution   stars: pre-main-sequence  

摘要： The second Gaia Data Release (DR2) contains astrometric and photometric data for more than 1.6 billion objects with mean Gaia G magnitude <20.7, including many Young Stellar Objects (YSOs) in different evolutionary stages. In order to explore the YSO population of the Milky Way, we combined the Gaia DR2 data base with Wide-field Infrared Survey Explorer (WISE) and Planck measurements and made an all-sky probabilistic catalogue of YSOs using machine learning techniques, such as Support Vector Machines, Random Forests, or Neural Networks. Our input catalogue contains 103 million objects from the DR2xAllWISE cross-match table. We classified each object into four main classes: YSOs, extragalactic objects, main-sequence stars, and evolved stars. At a 90 per cent probability threshold, we identified 1 129 295 YSO candidates. To demonstrate the quality and potential of our YSO catalogue, here we present two applications of it. (1) We explore the 3D structure of the Orion A star-forming complex and show that the spatial distribution of the YSOs classified by our procedure is in agreement with recent results from the literature. (2) We use our catalogue to classify published Gaia Science Alerts. As Gaia measures the sources at multiple epochs, it can efficiently discover transient events, including sudden brightness changes of YSOs caused by dynamic processes of their circumstellar disc. However, in many cases the physical nature of the published alert sources are not known. A cross-check with our new catalogue shows that about 30 per cent more of the published Gaia alerts can most likely be attributed to YSO activity. The catalogue can be also useful to identify YSOs among future Gaia alerts.

关键词： Depression   EEG   Ensemble model   Deep learning  

摘要： The diagnosis of depression almost exclusively depends on doctor-patient communication and scale analysis, which have the obvious disadvantages such as patient denial, poor sensitivity, subjective biases and inaccuracy. An objective, automated method that predicts clinical outcomes in depression is essential for increasing the accuracy of depression recognition and treatments. This paper aims at better recognizing depression using the transformation of EEG features and machine learning methods. An experiment based on emotional face stimuli task was conducted, and twenty-eight subjects' EEG data were recorded from 128-channel HydroCel Geodesic Sensor Net (HCGSN) by Net Station software. The Mini International Neuropsychiatric Interview (MINI) was used by psychiatrists as the criterion for diagnosis of depression patients. The power spectral density and activity were respectively extracted as original features using Auto-regress model and Hjorth algorithm with different time windows. Two separate approaches processed the features: ensemble learning and deep learning. For the ensemble learning, a deep forest transformed the original features to new features that potentially improve feature engineering and a support vector machine (SVM) that was applied as classifier. For deep learning method, we added spatial information of EEG caps to both features by image conversion and adopted convolutional neural network (CNN) to recognize them. The performance of both methods was evaluated for separated and total frequency bands. As a result, the best accuracy obtained was 89.02% when we used the ensemble model and power spectral density. The best accuracy of deep learning method was 84.75% using the activity. These experimental results prove the efficiency of the proposed methods and show that EEG could be used as a reliable indicator for depression recognition, which makes it possible for EEG-based portable system design and application in auxiliary depression recognition in th

关键词： Data mining   Random forest   CART   Decision tree   Food analysis  

摘要： In recent years, the variety and volume of data acquired by modern analytical instruments in order to conduct a better authentication of food has dramatically increased. Several pattern recognition tools have been developed to deal with the large volume and complexity of available trial data. The most widely used methods are principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), soft independent modelling by class analogy (SIMCA), k-nearest neighbours (kNN), parallel factor analysis (PARAFAC), and multivariate curve resolution-alternating least squares (MCR-ALS). Nevertheless, there are alternative data treatment methods, such as support vector machine (SVM), classification and regression tree (CART) and random forest (RF), that show a great potential and more advantages compared to conventional ones. In this paper, we explain the background of these methods and review and discuss the reported studies in which these three methods have been applied in the area of food quality and authenticity. In addition, we clarify the technical terminology used in this particular area of research.

关键词： Big data   Data integration   Farm matching   Probabilistic   Machine learning  

摘要： The advent of big data in agriculture increased the necessity of extracting useful information from large data collections. This knowledge is critical in optimizing production systems, while also addressing prevailing issues such as sustainability. One of the first, yet crucial, data analytics steps comprises integration. Integrated data from different sources can provide enhanced insight, as they may retain complementary information on the same entity. In the absence of a "unique universal identifier" to link entities (e.g. farms) from different databases, it is necessary to rely on their recorded attributes (e.g. farm name, owner). We propose a fully automated framework to match farms, across different datasets (i.e. farm matching) in a big data context. To assess performance, we used information on Brazilian beef cattle farms from two large datasets: 44,566 farms that made purchases at an animal nutrition company, and 32,776 that processed cattle at a meat packing company. Geographical search space reduction was implemented as an alternative to reduce the number of comparisons evaluated. To compare attributes between farm pairs, we contrasted two edit-based approaches, the Levenshtein and Jaro-Winkler metrics. We also compare deterministic, stochastic, and machine learning (ML) approaches, for classification of farm pairs as match or non-match. These techniques have been used in other record linkage domains. The deterministic approach requires all attributes to match exactly. The probabilistic approaches tested were Epi-Weights (CR) and Fellegi-Slunter (FS). Unsupervised ML approaches were k-means and bagged clustering (BC). Supervised methods were recursive partitioning trees, bagging of decision trees, bootstrap based classification trees, stochastic boosting, support vector machines (SVM), single-layer neural networks and logistic regression. Labels were produced by specialist review for both a training set of 295,012 comparison pairs and a testing set of 32,7

关键词： Gene prediction   Supervised learning   Markov model   Sequence encoding   Intron density  

摘要： Identification of splice sites is imperative for prediction of gene structure. Machine learning-based approaches (MLAs) have been reported to be more successful than the rule-based methods for identification of splice sites. However, the strings of alphabets should be transformed into numeric features through sequence encoding before using them as input in MLAs. In this study, we evaluated the performances of 8 different sequence encoding schemes i.e., Bayes kernel, density and sparse (DS), distribution of tri-nucleotide and 1st order Markov model (DM), frequency difference distance measure (FDDM), paired-nucleotide frequency difference between true and false sites (FDTF), 1st order Markov model (MM1), combination of both 1st and 2nd order Markov model (MM1 + MM2) and 2nd order Markov model (MM2) in respect of predicting donor and acceptor splice sites using 5 supervised learning methods (ANN, Bagging, Boosting, RF and SVM). The encoding schemes and machine learning methods were first evaluated in 4 species i.e., A. thaliana, C. elegans, D. melanogaster and H. sapiens, and then performances were validated with another four species i.e., Ciona intestinalis, Dictyostelium discoideum, Phaeodactylum tricornutum and Trypanosoma brucei. In terms of ROC (receiver-operating-characteristics) and PR (precision-recall) curves, FDTF encoding approach achieved higher accuracy followed by either MM2 or FDDM. Further, SVM was found to achieve higher accuracy (in terms of ROC and PR curves) followed by RF across encoding schemes and species. In terms of prediction accuracy across species, the SVM-FDTF combination was optimum than other combinations of classifiers and encoding schemes. Further, splice site prediction accuracies were observed higher for the species with low intron density. To our limited knowledge, this is the first attempt as far as comprehensive evaluation of sequence encoding schemes for prediction of splice sites is concerned. We have also developed an R-package

关键词： Generative adversarial networks  

摘要： To address the problem of unstable training and poor accuracy in image classification algorithms based on generative adversarial networks (GAN), a novel sensor network structure for classification processing using auxiliary classifier generative adversarial networks (ACGAN) is proposed in this paper. Firstly, the real/fake discrimination of sensor samples in the network has been canceled at the output layer of the discriminative network and only the posterior probability estimation of the sample tag is outputted. Secondly, by regarding the real sensor samples as supervised data and the generative sensor samples as labeled fake data, we have reconstructed the loss function of the generator and discriminator by using the real/fake attributes of sensor samples and the cross-entropy loss function of the label. Thirdly, the pooling and caching method has been introduced into the discriminator to enable more ekective extraction of the classification features. Finally, feature matching has been added to the discriminative network to ensure the diversity of the generative sensor samples. Experimental results have shown that the proposed algorithm (CP-ACGAN) achieves better classification accuracy on the MNIST dataset, CIFAR10 dataset and CIFAR100 dataset than other solutions. Moreover, when compared with the ACGAN and CNN classification algorithms, which have the same deep network structure as CP-ACGAN, the proposed method continues to achieve better classification effects and stability than other main existing sensor solutions. © Sensors (Switzerland) 2019. All Rights Reserved.

关键词： 储层分类   二分类问题   机器学习   线性支持向量机  

摘要： 油气田开发中有效储层和非有效储层的样本点存在混合带时,两类储层的划分是一个难点问题.从统计学上来看,其本质是一个含噪声的小样本二分类问题,可以采用机器学习方法,充分挖掘有试油成果的样本点的数据信息.分别利用线性判别分析、支持向量机、多层感知机神经网络建立储层分类模型,利用10次10折交叉验证法进行模型评估与优选,并利用全部样本点建立了有效的储层分类模型,最后将模型推广应用到样本分布的三种不同情形.结果表明,线性支持向量机模型具有最好的分类效果和很强的泛化能力,对于区分有效储层和非有效储层是有效的,可以在油气田开发中进行推广.

关键词： Syk   虚拟筛选   分子描述符   机器学习方法   C4.5决策树   随机森林  

摘要： 脾酪氨酸激酶(Syk)是一种细胞内的酪氨酸激酶细胞质受体,在类风湿性关节炎(RA)的发病过程中起着至关重要的作用。筛选Syk抑制剂对RA的治疗有着重要的意义。采用C4.5决策树与随机森林(RF)两种机器学习方法分别对Syk抑制剂与非抑制剂建立模型,经过对比,RF具有更好的预测精度。采用RF模型对Syk抑制剂进行虚拟筛选,从ZINC数据库筛选得到潜在的Syk抑制剂分子。研究结果表明,机器学习方法对于虚拟筛选和发现潜在的Syk抑制剂十分有效。

关键词： 相关向量机(RVM)   教学质量评价   精度分析   可靠性分析   遗传算法   置信区间  

摘要： 为提高高校理论教学与实验教学质量评价的精度及可靠性,基于机器学习新算法RVM构建高校理论教学与实验教学质量评价新模型。对RVM的核函数及参数确定方法进行改进,利用遗传算法优化的MK-RVM模型分别建立高校理论与实验教学质量评价的MK-RVM新模型,并构建基于置信区间的结果可靠性分析方法。实验结果表明,高校理论教学与实验教学质量评价MK-RVM模型的各项精度指标均表现优秀,精度等级达到“好”;训练集及测试集的教学质量评价真实值均在MK-RVM估计的95%置信度置信区间内,证实基于MK-RVM的教学质量评价结果具有较好的可靠性。因此,RVM算法为高校理论教学与实验教学质量评价提供了一种新的有效途径。