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Prediction of rare feature combinations in population synthesis: Application of deep generative modelling

TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2020年 120卷 102787-102787页

作者： Garrido, Sergio Borysov, Stanislav S. Pereira, Francisco C. Rich, Jeppe Tech Univ Denmark Dept Technol Management & Econ DTU DK-2800 Lyngby Denmark

Population synthesis is concerned with the generation of agents for agent-based modelling in many fields, such as economics, transportation, ecology and epidemiology. When the number of attributes describing the agents and/or their level of detail becomes large, survey data cannot densely support the joint distribution of the attributes in the population due to the curse of dimensionality. It leads to a situation where many attribute combinations are missing from the sample data while such combinations exist in the real population. In this case, it becomes essential to consider methods that are able to impute such missing information effectively. In this paper, we propose to use deep generative latent models. These models are able to learn a compressed representation of the data space, which when projected back to the original space, leads to an effective way of imputing information in the observed data space. Specifically, we employ the Wasserstein Generative Adversarial Network (WGAN) and the variational autoencoder (VAE) for a large-scale population synthesis application. The models are applied to a Danish travel survey with a feature-space of more than 60 variables and trained and tested using cross validation. A new metric that applies to the evaluation of generative models in an unsupervised setting is proposed. It is based on the ability to generate diverse yet valid synthetic attribute combinations by comparing if the models can recover missing combinations (sampling zeros) while keeping truly impossible combinations (structural zeros) models at a minimum. For a low dimensional experiment, the VAE, the marginal sampler and the fully random sampler generate 5%, 21% and 26% more structural zeros per sampling zero when compared to the WGAN. For a high dimensional case, these figures increase to 44%, 2217% and 170440% respectively. This research directly supports the development of agent-based systems and in particular cases where detailed socio-economic or geog

关键词： Population synthesis Generative modeling Deep learning Generative Adversarial Networks variational autoencoder Transportation modeling Agent-based modeling

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Prediction of the microstructure of cold-compacted Astaloy 85Mo with deep generative models

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COMPUTATIONAL MATERIALS SCIENCE 2024年 242卷

作者： Schenk, Oliver Becker, Marco Deng, Yuanbin Niemietz, Philipp Bergs, Thomas Broeckmann, Christoph Chair & Inst Mat Applicat Mech Engn Augustinerbach 4 D-52062 Aachen Germany Rhein Westfal TH Aachen Mfg Technol Inst MTI Campus Blvd 30 D-52074 Aachen Germany Fraunhofer Inst Prod Technol IPT Steinbachstr 17 D-52074 Aachen Germany

In powder metallurgy, iron -based powders are compacted to so-called green bodies, which undergo a subsequent sintering process. The microstructure of the green bodies affects the sintering process and the resulting properties of the produced component. Assessing the microstructure experimentally is time consuming and costly, while simulation approaches rely on simplifications that significantly affect relevant microstructural information. This work investigates the suitability of deep generative models to synthetically generate realistic micrographs of green bodies as an alternative to experiments and simulations. For that purpose experiments comparing Generative Adversarial Neural Networks and variational autoencoders were conducted. The two deep learning frameworks were used to train models which produce synthetic micrographs in dependence of two parameters, namely powder particle size and green body porosity. The data utilized to train and evaluate the models was acquired from compacted water -atomized Astaloy 85Mo via scanning electron microscopy. Besides visual inspection, the trained models were evaluated via quantitative metrics. Distributions of relevant microstructural parameters such as pore perimeter or minimum and maximum pore feret diameter of the synthetically generated micrographs were compared to those of experimentally acquired micrographs. The results indicate that Generative Adversarial Networks represent a promising approach to train models, which produce synthetic micrographs that capture relevant properties of green body micrographs in dependence of given parameters such as powder particle size. In contrast, the variational autoencoders trained for this study did not capture microstructural properties well.

关键词： Generative models Generative Adversarial Network variational autoencoder Micrograph Powder metallurgy Microstructure

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A Lightweight Unsupervised Intrusion Detection Model Based on variational Auto-Encoder

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SENSORS 2023年第20期23卷 8407页

作者： Ren, Yi Feng, Kanghui Hu, Fei Chen, Liangyin Chen, Yanru Sichuan Univ Sch Comp Sci Chengdu 610065 Peoples R China Sichuan Univ Inst Ind Internet Res Chengdu 610065 Peoples R China

With the gradual integration of internet technology and the industrial control field, industrial control systems (ICSs) have begun to access public networks on a large scale. Attackers use these public network interfaces to launch frequent invasions of industrial control systems, thus resulting in equipment failure and downtime, production data leakage, and other serious harm. To ensure security, ICSs urgently need a mature intrusion detection mechanism. Most of the existing research on intrusion detection in ICSs focuses on improving the accuracy of intrusion detection, thereby ignoring the problem of limited equipment resources in industrial control environments, which makes it difficult to apply excellent intrusion detection algorithms in practice. In this study, we first use the spectral residual (SR) algorithm to process the data;we then propose the improved lightweight variational autoencoder (LVA) with autoregression to reconstruct the data, and we finally perform anomaly determination based on the permutation entropy (PE) algorithm. We construct a lightweight unsupervised intrusion detection model named LVA-SP. The model as a whole adopts a lightweight design with a simpler network structure and fewer parameters, which achieves a balance between the detection accuracy and the system resource overhead. Experimental results on the ICSs dataset show that our proposed LVA-SP model achieved an F1-score of 84.81% and has advantages in terms of time and memory overhead.

关键词： industrial control systems intrusion detection variational autoencoder

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Layer-constrained variational autoencoding kernel density estimation model for anomaly detection

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KNOWLEDGE-BASED SYSTEMS 2020年 196卷 105753-105753页

作者： Lv, Peng Yu, Yanwei Fan, Yangyang Tang, Xianfeng Tong, Xiangrong Ocean Univ China Dept Comp Sci & Technol Qingdao 266100 Shandong Peoples R China Yantai Univ Sch Comp & Control Engn Yantai 264005 Shandong Peoples R China Shanghai Jiao Tong Univ Shanghai Key Lab Adv High Temp Mat & Precis Formi Shanghai 200240 Peoples R China Penn State Univ Coll Informat Sci & Technol University Pk PA 16802 USA

Unsupervised techniques typically rely on the probability density distribution of the data to detect anomalies, where objects with low probability density are considered to be abnormal. However, modeling the density distribution of high dimensional data is known to be hard, making the problem of detecting anomalies from high-dimensional data challenging. The state-of-the-art methods solve this problem by first applying dimension reduction techniques to the data and then detecting anomalies in the low dimensional space. Unfortunately, the low dimensional space does not necessarily preserve the density distribution of the original high dimensional data. This jeopardizes the effectiveness of anomaly detection. In this work, we propose a novel high dimensional anomaly detection method called LAKE. The key idea of LAKE is to unify the representation learning capacity of layer-constrained variational autoencoder with the density estimation power of kernel density estimation (KDE). Then a probability density distribution of the high dimensional data can be learned, which is able to effectively separate the anomalies out. LAKE successfully consolidates the merits of the two worlds, namely layer-constrained variational autoencoder and KDE by using a probability density-aware strategy in the training process of the autoencoder. Extensive experiments on six public benchmark datasets demonstrate that our method significantly outperforms the state-of-the-art methods in detecting anomalies and achieves up to 37% improvement in F-1 score. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Anomaly detection variational autoencoder Kernel density estimation Layer constraint Deep learning

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Research on Insider Threat Detection Method Based on variational Autoencoding

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电脑学刊 2021年第4期32卷 201-210页

作者： Zhenjiang Zhang Lulu Zhao Yang Zhang Hongde Zhou Wei Li

In recent years, internal attacks have posed a serious threat to the security of individuals, companies and even the country. Machine learning is currently a common method of insider threat detection. However, this technology requires a series of complex feature engineering, which has certain limitations in practical applications. This paper comprehensively considers the user's business operation behavior data and internal psychological data, and establishes an internal threat detection model to analyze their potential associations. The main tasks are as follows: In order to improve the fine-grained features of heterogeneous behavior log data and accurately reflect user behavior attributes, a session-based full feature extraction method is proposed. In this method, combined with a variational autoencoder, a long and shortterm memory variational autoencoder (LVE) model is proposed. Taking into account the time characteristics of user behavior, a long and short-term memory network is used in the codec part, that is, input data, generate hidden variables, and then restore output data through hidden variables. The results show that this method improves the recall rate compared with other algorithms. Finally, the main work and improvement prospects are summarized.

关键词： detection efficiency insider threat user behavior analysis variational autoencoder

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Separating group- and individual-level brain signatures in the newborn functional connectome: A deep learning approach

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NEUROIMAGE 2024年 299卷 120806-120806页

作者： Kim, Jung-Hoon De Asis-Cruz, Josepheen Limperopoulos, Catherine Childrens Natl Developing Brain Inst 111 Michigan Ave NW Washington DC 20010 USA

Recent studies indicate that differences in cognition among individuals may be partially attributed to unique brain wiring patterns. While functional connectivity (FC)-based fingerprinting has demonstrated high accuracy in identifying adults, early studies on neonates suggest that individualized FC signatures are absent. We posit that individual uniqueness is present in neonatal FC data and that conventional linear models fail to capture the rapid developmental trajectories characteristic of newborn brains. To explore this hypothesis, we employed a deep generative model, known as a variational autoencoder (VAE), leveraging two extensive public datasets: one comprising resting-state functional MRI (rs-fMRI) scans from 100 adults and the other from 464 neonates. VAE models trained on rs-fMRI from both adults and newborns produced superior age prediction performance (with r between predicted- and actual age similar to 0.7) and individual identification accuracy (similar to 45 %) compared to models trained solely on adult or neonatal data. The VAE model also showed significantly higher individual identification accuracy than linear models (=10 similar to 30 %). Importantly, the VAE differentiated connections reflecting age-related changes from those indicative of individual uniqueness, a distinction not possible with linear models. Moreover, we derived 20 latent variables, each corresponding to distinct patterns of cortical functional network (CFNs). These CFNs varied in their representation of brain maturation and individual signatures;notably, certain CFNs that failed to capture neurodevelopmental traits, in fact, exhibited individual signatures. CFNs associated with neonatal neurodevelopment predominantly encompassed unimodal regions such as visual and sensorimotor areas, whereas those linked to individual uniqueness spanned multimodal and transmodal brain regions. The VAE's capacity to extract features from rs-fMRI data beyond the capabilities of linear models posit

关键词： Neonate Resting-state fMRI variational autoencoder Subject identification Age prediction Individual uniqueness

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BioDSNN: a dual-stream neural network with hybrid biological knowledge integration for multi-gene perturbation response prediction

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BRIEFINGS IN BIOINFORMATICS 2024年第1期26卷 bbae617页

作者： Tan, Yuejun Xie, Linhai Yang, Hong Zhang, Qingyuan Luo, Jinyuan Zhang, Yanchun Guangzhou Univ Cyberspace Inst Adv Technol Guangzhou 510000 Peoples R China Zhejiang Normal Univ Sch Comp Sci & Technol Jinhua 321000 Peoples R China Natl Ctr Prot Sci Beijing State Key Lab Prote Beijing 100000 Peoples R China Int Acad Phronesis Med Guangzhou 510000 Peoples R China

Studying the outcomes of genetic perturbation based on single-cell RNA-seq data is crucial for understanding genetic regulation of cells. However, the high cost of cellular experiments and single-cell sequencing restrict us from measuring the full combination space of genetic perturbations and cell types. Consequently, a bunch of computational models have been proposed to predict unseen combinations based on existing data. Among them, generative models, e.g. variational autoencoder and diffusion models, have the superiority in capturing the perturbed data distribution, but lack a biologically understandable foundation for generalization. On the other side of the spectrum, Gene Regulation Networks or gene pathway knowledge have been exploited for more reasonable generalization enhancement. Unfortunately, they do not reach a balanced processing of the two data modalities, leading to a degraded fitting ability. Hence, we propose a dual-stream architecture. Before the information from two modalities are merged, the sequencing data are learned with a generative model while three types of knowledge data are comprehensively processed with graph networks and a masked transformer, enforcing a deep understanding of single-modality data, respectively. The benchmark results show an approximate 20% reduction in terms of mean squared error, proving the effectiveness of the model.

关键词： genetic perturbation predict biological knowledge masked attention variational autoencoder

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Semi-supervised Cavitation Detection for Centrifugal Pumps

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TRANSACTIONS OF THE KOREAN SOCIETY OF MECHANICAL ENGINEERS A 2022年第2期46卷 153-162页

作者： Yoo, Donghwi Choi, Minseok Kim, Chungeon Oh, Hyunseok Gwangju Inst Sci & Technol Sch Mech Engn Gwangju South Korea

Cavitation is a dominant failure mode that accelerates the wear and deterioration of pumps. Cavitation can lead to pump malfunction and, eventually, catastrophic failure of the whole system. Therefore, it is important to avoid cavitation in the pump. This paper proposes a semi-supervised learning method that detects cavitation in centrifugal pumps. One-dimensional (1D) vibration signals are converted into two-dimensional (2D) images by the short time Fourier transform. The severity of the cavitation is determined using the variational autoencoder and Mahalanobis distance. The effectiveness of the proposed method is evaluated using the data collected from a 0.75 kW hydraulic pump testbed. It is confirmed that the proposed method can detect cavitation with different severities and help avoid the cavitation phenomenon.

关键词： Anomaly Detection Short Time Fourier Transform variational autoencoder Mahalanobis Distance

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Convolutional Neural Network Graph-based Embedding for Neural Architecture Search

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Procedia Computer Science 2023年 229卷 47-54页

作者： Evgeny Bessonnitsyn Vsevolod Shaldin Valeria Efimova Viacheslav Shalamov ITMO University Kronverksky Pr. 49 bldg. A St. Petersburg 197101 Russia

Recently, network architecture search is gaining popularity. The neural network representation as a directed acyclic graph is considered for subsequent architecture optimization. Currently, most of the existing encoders rely only on the model layer properties and do not take into account the attributes of layers. This work proposes an algorithm for mapping a CNN network to a vector space considering the layer attributes, such as different dimensions of a particular layer. The proposed algorithm was compared with D-VAE and DVAE-EMB and showed less information loss caused by the mapping of a network to a vector space. As the results show, the performance of the model was shown after direct conversion to embedding and reverse conversion to architecture. The method allows more accurate neural network architecture mapping into a vector form, which will improve the search for the best architecture. The method implementation is publicly available at https://***/Turukmokto/GraphEmbedding-dev .

关键词： neural network architecture search vector representation variational autoencoder graphs with attributes

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Multi-Agent Reinforcement Learning with Clustering and Experience Sharing

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Procedia Computer Science 2024年 246卷 1329-1337页

作者： Kaname Inokuchi Toshiharu Sugawara Department of Computer Science and Communications Engineering Waseda University Japan

We propose a training method for a heterogeneous multi-agent system to improve the learning efficiency in sparse-reward environments. Although extensive research on multi-agent deep reinforcement learning are conducted actively, these studies often assume that all agents are homogeneous to share/utilize learning parameters in their networks. Unfortunately, this is not always the case in real-world applications where heterogeneous autonomous agents, i.e., those with different capabilities and perspectives, must properly cooperate and coordinate with each other. In our learning method, which is an extension of the shared experience actor-critic (SEAC) for a heterogeneous agent environment, agents are classified depending on their features (such as trajectories of the observations, actions and received rewards) using variational autoencoder, and share their experience among agents within each cluster to train their individual agents for improving the learning efficiency in a sparse-reward environment. Our experimental evaluation shows that the proposed method is capable of more efficient cooperative/coordinated behaviors than the baselines while remaining the advantages of SEAC.

关键词： Multi-agent deep reinforcement learning Experience Sharing variational autoencoder heterogeneous multi-agent systems Sparse-reward environment

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