11 research outputs found
Sample adaptive multiple kernel learning for failure prediction of railway points
© 2019 Association for Computing Machinery. Railway points are among the key components of railway infrastructure. As a part of signal equipment, points control the routes of trains at railway junctions, having a significant impact on the reliability, capacity, and punctuality of rail transport. Meanwhile, they are also one of the most fragile parts in railway systems. Points failures cause a large portion of railway incidents. Traditionally, maintenance of points is based on a fixed time interval or raised after the equipment failures. Instead, it would be of great value if we could forecast points' failures and take action beforehand, min-imising any negative effect. To date, most of the existing prediction methods are either lab-based or relying on specially installed sensors which makes them infeasible for large-scale implementation. Besides, they often use data from only one source. We, therefore, explore a new way that integrates multi-source data which are ready to hand to fulfil this task. We conducted our case study based on Sydney Trains rail network which is an extensive network of passenger and freight railways. Unfortunately, the real-world data are usually incomplete due to various reasons, e.g., faults in the database, operational errors or transmission faults. Besides, railway points differ in their locations, types and some other properties, which means it is hard to use a unified model to predict their failures. Aiming at this challenging task, we firstly constructed a dataset from multiple sources and selected key features with the help of domain experts. In this paper, we formulate our prediction task as a multiple kernel learning problem with missing kernels. We present a robust multiple kernel learning algorithm for predicting points failures. Our model takes into account the missing pattern of data as well as the inherent variance on different sets of railway points. Extensive experiments demonstrate the superiority of our algorithm compared with other state-of-the-art methods
Fast Continual Multi-View Clustering with Incomplete Views
Multi-view clustering (MVC) has gained broad attention owing to its capacity
to exploit consistent and complementary information across views. This paper
focuses on a challenging issue in MVC called the incomplete continual data
problem (ICDP). In specific, most existing algorithms assume that views are
available in advance and overlook the scenarios where data observations of
views are accumulated over time. Due to privacy considerations or memory
limitations, previous views cannot be stored in these situations. Some works
are proposed to handle it, but all fail to address incomplete views. Such an
incomplete continual data problem (ICDP) in MVC is tough to solve since
incomplete information with continual data increases the difficulty of
extracting consistent and complementary knowledge among views. We propose Fast
Continual Multi-View Clustering with Incomplete Views (FCMVC-IV) to address it.
Specifically, it maintains a consensus coefficient matrix and updates knowledge
with the incoming incomplete view rather than storing and recomputing all the
data matrices. Considering that the views are incomplete, the newly collected
view might contain samples that have yet to appear; two indicator matrices and
a rotation matrix are developed to match matrices with different dimensions.
Besides, we design a three-step iterative algorithm to solve the resultant
problem in linear complexity with proven convergence. Comprehensive experiments
on various datasets show the superiority of FCMVC-IV
Contrastive Continual Multi-view Clustering with Filtered Structural Fusion
Multi-view clustering thrives in applications where views are collected in
advance by extracting consistent and complementary information among views.
However, it overlooks scenarios where data views are collected sequentially,
i.e., real-time data. Due to privacy issues or memory burden, previous views
are not available with time in these situations. Some methods are proposed to
handle it but are trapped in a stability-plasticity dilemma. In specific, these
methods undergo a catastrophic forgetting of prior knowledge when a new view is
attained. Such a catastrophic forgetting problem (CFP) would cause the
consistent and complementary information hard to get and affect the clustering
performance. To tackle this, we propose a novel method termed Contrastive
Continual Multi-view Clustering with Filtered Structural Fusion (CCMVC-FSF).
Precisely, considering that data correlations play a vital role in clustering
and prior knowledge ought to guide the clustering process of a new view, we
develop a data buffer with fixed size to store filtered structural information
and utilize it to guide the generation of a robust partition matrix via
contrastive learning. Furthermore, we theoretically connect CCMVC-FSF with
semi-supervised learning and knowledge distillation. Extensive experiments
exhibit the excellence of the proposed method
Multi-View Class Incremental Learning
Multi-view learning (MVL) has gained great success in integrating information
from multiple perspectives of a dataset to improve downstream task performance.
To make MVL methods more practical in an open-ended environment, this paper
investigates a novel paradigm called multi-view class incremental learning
(MVCIL), where a single model incrementally classifies new classes from a
continual stream of views, requiring no access to earlier views of data.
However, MVCIL is challenged by the catastrophic forgetting of old information
and the interference with learning new concepts. To address this, we first
develop a randomization-based representation learning technique serving for
feature extraction to guarantee their separate view-optimal working states,
during which multiple views belonging to a class are presented sequentially;
Then, we integrate them one by one in the orthogonality fusion subspace spanned
by the extracted features; Finally, we introduce selective weight consolidation
for learning-without-forgetting decision-making while encountering new classes.
Extensive experiments on synthetic and real-world datasets validate the
effectiveness of our approach.Comment: 34 pages,4 figures. Under revie
Comparisons of various imputation methods for incomplete water quality data: a case study of the Langat River, Malaysia
In this study, the ability of numerous statistical and machine learning models to impute water quality data was investigated at three monitoring stations along the Langat River in Malaysia. Inconsistencies in the percentage of missing data between monitoring stations (varying from 20 percent (moderate) to over 50 percent (high)) represent the greatest obstacle of the study. The main objective was to select the best method for imputation and compare whether there are differences between the methods used by the different stations. The paper focuses on different imputation methods such as Multiple Predictive Mean Matching (PMM), Multiple Random Forest Imputation (RF), Multiple Bayesian Linear Regression Imputation (BLR), Multiple Linear Regression (non-Bayesian) Imputation (LRNB), Multiple Classification and Regression Tree (CART), k-nearest neighbours (kNN) and Bootstrap-based Expectation Maximisation (EMB). Remarkably, among all seven imputation techniques, the kNN produces identically reliable results. The imputed data is all rated as ‘very good’ (NSE > 0.75). This was confirmed by the calculation of |PBIAS|<5.30 (all imputed data are‘very good’) and KGE≥0.87 (all imputations are rated as’ good’). Imputation performance improves for all three monitoring stations with an index of agreement, WI ≥ 0.94, despite varying percentages of missing data. According to the findings, the kNN imputation approach outperforms the others and should be prioritised in actual use. Future research with the existing methods could benefit from the addition of geographical data
Absent multiple kernel learning
Copyright © 2015, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Multiple kernel learning (MKL) optimally combines the multiple channels of each sample to improve classification performance. However, existing MKL algorithms cannot effectively handle the situation where some channels are missing, which is common in practical applications. This paper proposes an absent MKL (AMKL) algorithm to address this issue. Different from existing approaches where missing channels are firstly imputed and then a standard MKL algorithm is deployed on the imputed data, our algorithm directly classifies each sample with its observed channels. In specific, we define a margin for each sample in its own relevant space, which corresponds to the observed channels of that sample. The proposed AMKL algorithm then maximizes the minimum of all sample-based margins, and this leads to a difficult optimization problem. We show that this problem can be reformulated as a convex one by applying the representer theorem. This makes it readily be solved via existing convex optimization packages. Extensive experiments are conducted on five MKL benchmark data sets to compare the proposed algorithm with existing imputation-based methods. As observed, our algorithm achieves superior performance and the improvement is more significant with the increasing missing ratio
Absent multiple kernel learning algorithms
Abstract
Multiple kernel learning (MKL) has been intensively studied during the past decade. It optimally combines the multiple channels of each sample to improve classification performance. However, existing MKL algorithms cannot effectively handle the situation where some channels of the samples are missing, which is not uncommon in practical applications. This paper proposes three absent MKL (AMKL) algorithms to address this issue. Different from existing approaches where missing channels are firstly imputed and then a standard MKL algorithm is deployed on the imputed data, our algorithms directly classify each sample based on its observed channels, without performing imputation. Specifically, we define a margin for each sample in its own relevant space, a space corresponding to the observed channels of that sample. The proposed AMKL algorithms then maximize the minimum of all sample-based margins, and this leads to a difficult optimization problem. We first provide two two-step iterative algorithms to approximately solve this problem. After that, we show that this problem can be reformulated as a convex one by applying the representer theorem. This makes it readily be solved via existing convex optimization packages. In addition, we provide a generalization error bound to justify the proposed AMKL algorithms from a theoretical perspective. Extensive experiments are conducted on nine UCI and six MKL benchmark datasets to compare the proposed algorithms with existing imputation-based methods. As demonstrated, our algorithms achieve superior performance and the improvement is more significant with the increase of missing ratio