651 research outputs found
Resilience of Dynamic Routing in the Face of Recurrent and Random Sensing Faults
Feedback dynamic routing is a commonly used control strategy in
transportation systems. This class of control strategies relies on real-time
information about the traffic state in each link. However, such information may
not always be observable due to temporary sensing faults. In this article, we
consider dynamic routing over two parallel routes, where the sensing on each
link is subject to recurrent and random faults. The faults occur and clear
according to a finite-state Markov chain. When the sensing is faulty on a link,
the traffic state on that link appears to be zero to the controller. Building
on the theories of Markov processes and monotone dynamical systems, we derive
lower and upper bounds for the resilience score, i.e. the guaranteed throughput
of the network, in the face of sensing faults by establishing stability
conditions for the network. We use these results to study how a variety of key
parameters affect the resilience score of the network. The main conclusions
are: (i) Sensing faults can reduce throughput and destabilize a nominally
stable network; (ii) A higher failure rate does not necessarily reduce
throughput, and there may exist a worst rate that minimizes throughput; (iii)
Higher correlation between the failure probabilities of two links leads to
greater throughput; (iv) A large difference in capacity between two links can
result in a drop in throughput.Comment: 17 pages, 4 figures, accepted by ACC 202
Time-Varying Graphs and Dynamic Networks
The past few years have seen intensive research efforts carried out in some
apparently unrelated areas of dynamic systems -- delay-tolerant networks,
opportunistic-mobility networks, social networks -- obtaining closely related
insights. Indeed, the concepts discovered in these investigations can be viewed
as parts of the same conceptual universe; and the formal models proposed so far
to express some specific concepts are components of a larger formal description
of this universe. The main contribution of this paper is to integrate the vast
collection of concepts, formalisms, and results found in the literature into a
unified framework, which we call TVG (for time-varying graphs). Using this
framework, it is possible to express directly in the same formalism not only
the concepts common to all those different areas, but also those specific to
each. Based on this definitional work, employing both existing results and
original observations, we present a hierarchical classification of TVGs; each
class corresponds to a significant property examined in the distributed
computing literature. We then examine how TVGs can be used to study the
evolution of network properties, and propose different techniques, depending on
whether the indicators for these properties are a-temporal (as in the majority
of existing studies) or temporal. Finally, we briefly discuss the introduction
of randomness in TVGs.Comment: A short version appeared in ADHOC-NOW'11. This version is to be
published in Internation Journal of Parallel, Emergent and Distributed
System
A critical review of cyber-physical security for building automation systems
Modern Building Automation Systems (BASs), as the brain that enables the
smartness of a smart building, often require increased connectivity both among
system components as well as with outside entities, such as optimized
automation via outsourced cloud analytics and increased building-grid
integrations. However, increased connectivity and accessibility come with
increased cyber security threats. BASs were historically developed as closed
environments with limited cyber-security considerations. As a result, BASs in
many buildings are vulnerable to cyber-attacks that may cause adverse
consequences, such as occupant discomfort, excessive energy usage, and
unexpected equipment downtime. Therefore, there is a strong need to advance the
state-of-the-art in cyber-physical security for BASs and provide practical
solutions for attack mitigation in buildings. However, an inclusive and
systematic review of BAS vulnerabilities, potential cyber-attacks with impact
assessment, detection & defense approaches, and cyber-secure resilient control
strategies is currently lacking in the literature. This review paper fills the
gap by providing a comprehensive up-to-date review of cyber-physical security
for BASs at three levels in commercial buildings: management level, automation
level, and field level. The general BASs vulnerabilities and protocol-specific
vulnerabilities for the four dominant BAS protocols are reviewed, followed by a
discussion on four attack targets and seven potential attack scenarios. The
impact of cyber-attacks on BASs is summarized as signal corruption, signal
delaying, and signal blocking. The typical cyber-attack detection and defense
approaches are identified at the three levels. Cyber-secure resilient control
strategies for BASs under attack are categorized into passive and active
resilient control schemes. Open challenges and future opportunities are finally
discussed.Comment: 38 pages, 7 figures, 6 tables, submitted to Annual Reviews in Contro
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Multi-Channel LSTM-Capsule Autoencoder Network for Anomaly Detection on Multivariate Data
Data Availability Statement: The dataset used in this study are available from the authors upon reasonable request.Copyright © 2022 by the authors. Deep learning techniques have recently shown promise in the field of anomaly detection, providing a flexible and effective method of modelling systems in comparison to traditional statistical modelling and signal processing-based methods. However, there are a few issues that Neural Networks (NN)s face, such as generalisation ability, requiring large volumes of labelled data to train effectively, and understanding spatial context in data. This paper introduces a novel NN architecture to tackle these problems, which utilises a Long-Short-Term-Memory (LSTM) encoder and Capsule decoder in a multi-channel input Autoencoder architecture for use on multivariate time series data. Experimental results show that using Capsule decoders increases the resilience of the model to overfitting and improves training efficiency, which is shown by the improvement of Mean Squared Error (MSE) on unseen data from an average of 10.61 to 2.08 for single channel architectures, and 10.08 to 2.05 for multi-channel architectures. Additionally, results also show that the proposed model can learn multivariate data more consistently, and was not affected by outliers in the training data. The proposed architecture was also tested on an open-source benchmark, where it achieved state-of-the-art performance in outlier detection, and performs best overall with a total accuracy of 0.494 over the metrics tested.Partially funded by a company that wishes to keep their name anonymous
Failure Analysis in Next-Generation Critical Cellular Communication Infrastructures
The advent of communication technologies marks a transformative phase in
critical infrastructure construction, where the meticulous analysis of failures
becomes paramount in achieving the fundamental objectives of continuity,
security, and availability. This survey enriches the discourse on failures,
failure analysis, and countermeasures in the context of the next-generation
critical communication infrastructures. Through an exhaustive examination of
existing literature, we discern and categorize prominent research orientations
with focuses on, namely resource depletion, security vulnerabilities, and
system availability concerns. We also analyze constructive countermeasures
tailored to address identified failure scenarios and their prevention.
Furthermore, the survey emphasizes the imperative for standardization in
addressing failures related to Artificial Intelligence (AI) within the ambit of
the sixth-generation (6G) networks, accounting for the forward-looking
perspective for the envisioned intelligence of 6G network architecture. By
identifying new challenges and delineating future research directions, this
survey can help guide stakeholders toward unexplored territories, fostering
innovation and resilience in critical communication infrastructure development
and failure prevention
Structure and topology of transcriptional regulatory networks and their applications in bio-inspired networking
Biological networks carry out vital functions necessary for sustenance despite environmental adversities. Transcriptional Regulatory Network (TRN) is one such biological network that is formed due to the interaction between proteins, called Transcription Factors (TFs), and segments of DNA, called genes. TRNs are known to exhibit functional robustness in the face of perturbation or mutation: a property that is proven to be a result of its underlying network topology. In this thesis, we first propose a three-tier topological characterization of TRN to analyze the interplay between the significant graph-theoretic properties of TRNs such as scale-free out-degree distribution, low graph density, small world property and the abundance of subgraphs called motifs. Specifically, we pinpoint the role of a certain three-node motif, called Feed Forward Loop (FFL) motif in topological robustness as well as information spread in TRNs.
With the understanding of the TRN topology, we explore its potential use in design of fault-tolerant communication topologies. To this end, we first propose an edge rewiring mechanism that remedies the vulnerability of TRNs to the failure of well-connected nodes, called hubs, while preserving its other significant graph-theoretic properties. We apply the rewired TRN topologies in the design of wireless sensor networks that are less vulnerable to targeted node failure. Similarly, we apply the TRN topology to address the issues of robustness and energy-efficiency in the following networking paradigms: robust yet energy-efficient delay tolerant network for post disaster scenarios, energy-efficient data-collection framework for smart city applications and a data transfer framework deployed over a fog computing platform for collaborative sensing --Abstract, page iii
Generative AI for Unmanned Vehicle Swarms: Challenges, Applications and Opportunities
With recent advances in artificial intelligence (AI) and robotics, unmanned
vehicle swarms have received great attention from both academia and industry
due to their potential to provide services that are difficult and dangerous to
perform by humans. However, learning and coordinating movements and actions for
a large number of unmanned vehicles in complex and dynamic environments
introduce significant challenges to conventional AI methods. Generative AI
(GAI), with its capabilities in complex data feature extraction,
transformation, and enhancement, offers great potential in solving these
challenges of unmanned vehicle swarms. For that, this paper aims to provide a
comprehensive survey on applications, challenges, and opportunities of GAI in
unmanned vehicle swarms. Specifically, we first present an overview of unmanned
vehicles and unmanned vehicle swarms as well as their use cases and existing
issues. Then, an in-depth background of various GAI techniques together with
their capabilities in enhancing unmanned vehicle swarms are provided. After
that, we present a comprehensive review on the applications and challenges of
GAI in unmanned vehicle swarms with various insights and discussions. Finally,
we highlight open issues of GAI in unmanned vehicle swarms and discuss
potential research directions.Comment: 23 page
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