15 research outputs found
Ball Mill Fault Prediction Based on Deep Convolutional Auto-Encoding Network
Ball mills play a critical role in modern mining operations, making their
bearing failures a significant concern due to the potential loss of production
efficiency and economic consequences. This paper presents an anomaly detection
method based on Deep Convolutional Auto-encoding Neural Networks (DCAN) for
addressing the issue of ball mill bearing fault detection. The proposed
approach leverages vibration data collected during normal operation for
training, overcoming challenges such as labeling issues and data imbalance
often encountered in supervised learning methods. DCAN includes the modules of
convolutional feature extraction and transposed convolutional feature
reconstruction, demonstrating exceptional capabilities in signal processing and
feature extraction. Additionally, the paper describes the practical deployment
of the DCAN-based anomaly detection model for bearing fault detection,
utilizing data from the ball mill bearings of Wuhan Iron & Steel Resources
Group and fault data from NASA's bearing vibration dataset. Experimental
results validate the DCAN model's reliability in recognizing fault vibration
patterns. This method holds promise for enhancing bearing fault detection
efficiency, reducing production interruptions, and lowering maintenance costs.Comment: 9 pages, 11 figure
Feature-based Transferable Disruption Prediction for future tokamaks using domain adaptation
The high acquisition cost and the significant demand for disruptive
discharges for data-driven disruption prediction models in future tokamaks pose
an inherent contradiction in disruption prediction research. In this paper, we
demonstrated a novel approach to predict disruption in a future tokamak only
using a few discharges based on a domain adaptation algorithm called CORAL. It
is the first attempt at applying domain adaptation in the disruption prediction
task. In this paper, this disruption prediction approach aligns a few data from
the future tokamak (target domain) and a large amount of data from the existing
tokamak (source domain) to train a machine learning model in the existing
tokamak. To simulate the existing and future tokamak case, we selected J-TEXT
as the existing tokamak and EAST as the future tokamak. To simulate the lack of
disruptive data in future tokamak, we only selected 100 non-disruptive
discharges and 10 disruptive discharges from EAST as the target domain training
data. We have improved CORAL to make it more suitable for the disruption
prediction task, called supervised CORAL. Compared to the model trained by
mixing data from the two tokamaks, the supervised CORAL model can enhance the
disruption prediction performance for future tokamaks (AUC value from 0.764 to
0.890). Through interpretable analysis, we discovered that using the supervised
CORAL enables the transformation of data distribution to be more similar to
future tokamak. An assessment method for evaluating whether a model has learned
a trend of similar features is designed based on SHAP analysis. It demonstrates
that the supervised CORAL model exhibits more similarities to the model trained
on large data sizes of EAST. FTDP provides a light, interpretable, and
few-data-required way by aligning features to predict disruption using small
data sizes from the future tokamak.Comment: 15 pages, 9 figure
Disruption Precursor Onset Time Study Based on Semi-supervised Anomaly Detection
The full understanding of plasma disruption in tokamaks is currently lacking,
and data-driven methods are extensively used for disruption prediction.
However, most existing data-driven disruption predictors employ supervised
learning techniques, which require labeled training data. The manual labeling
of disruption precursors is a tedious and challenging task, as some precursors
are difficult to accurately identify, limiting the potential of machine
learning models. To address this issue, commonly used labeling methods assume
that the precursor onset occurs at a fixed time before the disruption, which
may not be consistent for different types of disruptions or even the same type
of disruption, due to the different speeds at which plasma instabilities
escalate. This leads to mislabeled samples and suboptimal performance of the
supervised learning predictor. In this paper, we present a disruption
prediction method based on anomaly detection that overcomes the drawbacks of
unbalanced positive and negative data samples and inaccurately labeled
disruption precursor samples. We demonstrate the effectiveness and reliability
of anomaly detection predictors based on different algorithms on J-TEXT and
EAST to evaluate the reliability of the precursor onset time inferred by the
anomaly detection predictor. The precursor onset times inferred by these
predictors reveal that the labeling methods have room for improvement as the
onset times of different shots are not necessarily the same. Finally, we
optimize precursor labeling using the onset times inferred by the anomaly
detection predictor and test the optimized labels on supervised learning
disruption predictors. The results on J-TEXT and EAST show that the models
trained on the optimized labels outperform those trained on fixed onset time
labels.Comment: 21 pages, 11 figure
Charged Particle (Negative Ion)-Based Cloud Seeding and Rain Enhancement Trial Design and Implementation
China has been suffering from water shortage for a long time. Weather modification and rainfall enhancement via cloud seeding has been proved to be effective to alleviate the problem. Current cloud seeding methods mostly rely on solid carbon dioxide and chemicals such as silver iodide and hygroscopic salts, which may have negative impacts on the environment and are expensive to operate. Lab experiments have proved the efficiency of ion-based cloud seeding compared with traditional methods. Moreover, it is also more environmentally friendly and more economical to operate at a large scale. Thus, it is necessary to carry out a field experiment to further investigate the characteristics and feasibility of the method. This paper provides the design and implementation of the ion-based cloud seeding and rain enhancement trial currently running in Northwest China. It introduces the basic principle of the trial and the devices developed for it, as well as the installation of the bases and the evaluation method design for the trial
Determination of the number of events at BESIII
The numbers of ψ(3686) events accumulated by the BESIII detector for the data taken during 2009 and 2012 are determined to be and , respectively, by counting inclusive hadronic events, where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ(3686) events for the two data taking periods is