Dynamic Network Research Articles

Reliable communication in dynamic networks with locally bounded byzantine faults

The Byzantine tolerant reliable communication primitive is a fundamental building block in distributed systems that guarantees the authenticity, integrity, and delivery of information exchanged between processes.We study the implementability of such a primitive in a distributed system with a dynamic communication network (i.e., where the set of available communication channels changes over time). We assume the f-locally bounded Byzantine fault model and identify the conditions on the dynamic communication networks that allow reliable communication between all pairs of processes. In addition, we investigate its implementability on several classes of dynamic networks and provide insights into its use in asynchronous distributed systems.

Effects of packetization on communication dynamics in brain networks

Abstract Computational studies in network neuroscience build models of communication dynamics in the connectome that help us understand the structure-function relationships of the brain. In these models, the dynamics of cortical signal transmission in brain networks are approximated with simple propagation strategies such as random walks and shortest path routing. Furthermore, the signal transmission dynamics in brain networks can be associated with the switching architectures of engineered communication systems (e.g., message switching and packet switching). However, it has been unclear how propagation strategies and switching architectures are related in models of brain network communication. Here, we investigate the effects of the difference between packet switching and message switching (i.e., whether signals are packetized or not) on the transmission completion time of propagation strategies when simulating signal propagation in mammalian brain networks. The results show that packetization in the connectome with hubs increases the time of the random walk strategy and does not change that of the shortest path strategy, but decreases that of more plausible strategies for brain networks that balance between communication speed and information requirements. This finding suggests an advantage of packet-switched communication in the connectome and provides new insights into modeling the communication dynamics in brain networks.

Abnormal static and dynamic brain network connectivity associated with chronic tinnitus

In order to comprehensively understand the changes of brain networks in patients with chronic tinnitus, this study combined static and dynamic analysis methods to explore the abnormalities of brain networks. Thirty-two patients with chronic tinnitus and 30 age-, sex- and education-matched healthy controls (HC) were recruited. Independent component analysis was used to identify resting-state networks (RSNs). Static and dynamic functional network connectivity (FNC) were performed. The temporal properties of brain network including mean dwell time (MDT), fraction time (FT) and numbers of transitions (NT) were calculated. Two-sample t test and Spearman’s correlation were used for group compares and correlation analysis. Four RSNs showed abnormal FNC including auditory network (AUN), default mode network (DMN), attention network (AN) and sensorimotor network (SMN). For static analysis, tinnitus patients showed significantly decreased FNC in AUN-DMN, AUN-AN, DMN-AN, and DMN-SMN than HC [p < 0.05, false discovery rate (FDR) corrected]. For dynamic analysis, tinnitus patients showed significantly decreased FNC in DMN-AN in state 3 (p < 0.05, FDR corrected). MDT in state 3 was significantly decreased in tinnitus patients (t = 2.039, P = 0.046). In the tinnitus group, the score of tinnitus functional index (TFI) was negatively correlated with MDT and FT in state 4, and the duration of tinnitus was positively correlated with FT in state 1 and NT. Chronic tinnitus causes abnormal brain network connectivity. These abnormal brain networks help to clarify the mechanism of tinnitus generation and chronicity, and provide a potential basis for the treatment of tinnitus.

Automatic construction and optimization method of enterprise data asset knowledge graph based on graph attention network

Traditional knowledge graph construction methods often rely on a large amount of human intervention and specialized knowledge, which seems inefficient and error-prone when dealing with massive, multi-source, and heterogeneous data assets of enterprises. To address this issue, a Multi Neighborhood Awareness Network (MNAN) model was proposed, which combines a multi language pre training model based on Bidirectional Encoder Representations from Transformers (BERT) and a Graph Convolutional Neural Network (GCN). By introducing an improved attention mechanism to deeply explore the neighborhood characteristics of entities, the accuracy and efficiency of entity matching are enhanced. In addition, to improve the integrity of the knowledge graph, a dynamic graph attention network (RDGAT) model based on graph attention network fusion relationship features is proposed. Through dynamic attention mechanism and relationship fusion strategy, deep learning of relationship features is carried out to optimize the completion performance of the knowledge graph spectrum. The performance test results show that the Hits@1 metric of the multi-neighborhood perceptual network model is close to 90% as the proportion of aligned entity seeds increases to 50%; the average inverse rank of the dynamic graph attention network on the test dataset improves by 6.3%. The experimental results show that the research-proposed knowledge graph fusion and complementation model exhibits significant effectiveness in automatically identifying and integrating large-scale, multi-source heterogeneous data at the enterprise level, and can significantly improve the automation level and accuracy of knowledge graph construction. The research method has achieved significant results in the data asset knowledge graph of petroleum enterprises and other fields, providing strong support for applications such as intelligent search, recommendation systems, and semantic analysis.

Dynamically reversible cross-linked polymer electrolytes with highly ionic conductivity for dendrite-free lithium metal batteries

High-safety PEO-based electrolytes have attracted widespread attention, but their inefficient conduction of Li ions and poor contact with electrode interfaces deteriorate the performances of rechargeable lithium metal batteries. Herein, we design a vitrimer polymer electrolyte (V-SPE-PEG) with abundant dynamic imine bonds via Schiff base reaction between aldehyde and ammonia, which achieves high ionic conductivity and good interfacial compatibility with lithium anode. The dynamic polymer network in V-SPE-PEG exhibits solid-state plasticity because reversible imine bonding reactions enable the integrity of the polymer network to be maintained while altering the cross-linked points under external stimuli. Therefore, this 3D dynamic cross-linked network effectively facilitates the polymer chain dynamics and meanwhile enhances ionic conductivity. Additionally, dynamic bond exchange fosters electrolyte flowability and self-healing during lithium deposition, promoting a tightly integrated electrode/electrolyte interface while inhibiting lithium dendrites growth. Consequently, lithium symmetric cells utilizing the V-SPE-PEG electrolyte demonstrate exceptional long-term cycling stability, surpassing 1100 h and exhibit outstanding ionic conductivity of 2.7 × 10−4 S cm−1 at 30 °C. The LiFePO4||Li battery maintains stable cycling performance at both 40 °C and 60 °C. This study introduces an innovative approach to designing solid-state electrolytes for lithium-metal batteries.

Efficiency analysis of China's urban water supply utilities using a dynamic network DEA model

Urban water scarcity and severe consumption challenges are crucial for improving performance in the urban water supply industry. Urban Water Supply Utilities (UWSUs) perform the primary task of providing tap water to city residents, and regulators use benchmarks to monitor UWSU operations. To assess the efficiency of UWSUs in detail, this study introduces a dynamic two-stage network data envelopment analysis (DEA) model with shared inputs and shared carryover. This model decomposes UWSU operations into water production (WP) and water distribution (WD) subprocesses. By combining dynamic features with network DEA, the study extends the static network DEA to a more general case for evaluating UWSU efficiency. The study sample includes 246 UWSUs from 24 provinces in China over the period 2016–2018. The analysis covers overall efficiency, period efficiency, subprocess efficiency, and regional disparities among the sampled water utilities. The findings indicate that the average efficiency of the UWSUs was 0.643 during 2016–2018, with slightly lower efficiency in the WP subprocess. UWSUs in the eastern provinces outperformed those in the central and western provinces, which require significant improvements. To enhance the performance of China's water supply sector, accelerated market competition and infrastructure improvements are necessary.

Traffic prediction based on spatial-temporal disentangled generative models

Understanding the underlying spatial-temporal patterns in a traffic network is crucial for accurate predictions. However, current deep learning techniques often struggle to effectively identify the generative factors hidden in spatial-temporal traffic data, leading to a lack of interpretability. To address this challenge, we have developed an innovative generative model called Spatial-Temporal Disentangled Neural Relational Inference (STDNRI) for traffic prediction and disentangling interpretable generative factors within observed traffic network data. In this study, we assume that spatial-temporal data is dominated by three generative factors: time-correlated factors, spatial-correlated factors and spatial-temporal joint correlation factors. Based on information bottleneck theory, we establish a novel objective function to maximize the disentanglement of different factors. To model the probability distributions of three factors, we propose three graph neural network encoders to represent time-correlated factors using a graph containing only self-loops, and denote spatial-correlated factors as well as spatial-temporal joint correlation factors adopting a fully-connected graph without self-loops. Then, graph neural network decoder with a spatial-temporal message passing mechanism is used to generate the final predictions. Several comprehensive experiments were conducted based on two real datasets from NYC Yellow Taxi and SHMetro. The results indicate that our STDNRI outperforms ten existing competitive models in terms of high prediction accuracy and provides excellent interpretability for generative factors. Furthermore, the disentangled interpretable factors can afford valuable insights for planners, urban developers, and other stakeholders to gain a deeper understanding of the dynamics of the traffic network, thus enabling more informed decision-making.

Improving deep neural network random initialization through neuronal rewiring

The deep learning literature is continuously updated with new architectures and training techniques. However, weight initialization is overlooked by most recent research, despite some intriguing findings regarding random weights. On the other hand, recent works have been approaching Network Science to understand the structure and dynamics of Artificial Neural Networks (ANNs) after training. Therefore, in this work, we analyze the centrality of neurons in randomly initialized networks. We show that a higher neuronal strength variance may decrease performance, while a lower neuronal strength variance usually improves it. A new method is then proposed to rewire neuronal connections according to a preferential attachment (PA) rule based on their strength, which significantly reduces the strength variance of layers initialized by common methods. In this sense, PA rewiring only reorganizes connections, while preserving the magnitude and distribution of the weights. We show through an extensive statistical analysis on image classification tasks that performance is improved in most cases, both during training and testing, when using both simple and complex architectures and learning schedules. Our results show that, aside from the magnitude, the organization of the weights is also relevant for better initialization of deep ANNs.

Epidemic dynamics of complex networks under pulse treatment and vaccination

The dynamics of a new Susceptible-Vaccinated-Infected-Recovered (SVIR) epidemic model in complex networks under constant and pulse control are investigated. Firstly, the epidemic model in complex networks under constant control is proposed. Utilizing the basic reproduction number, the sufficient conditions for stabilizing the epidemic under constant control are established. Since constant control is not conducive to resource conservation, it has been replaced by pulse control in epidemic model. The paper demonstrates the global attractiveness of the disease-free periodic solution of the model under pulse treatment and pulse vaccination. In addition, a sufficient condition is put forward to make sure that the system persists under pulse control, indicating periodic outbreaks of the epidemic. Furthermore, the epidemic is uniformly persistent when the pulse period is greater than the pulse period threshold or the vaccination rate is less than the vaccination threshold. Finally, several numerical simulations prove the feasibility of the theoretical results. By comparing the pulse period with a critical value, the strategy that most contributes to controlling the epidemic propagation is chosen from constant control and pulse control to achieve maximum utilization of resources. Moreover, it shows that decreasing the fraction of pulse treatment and pulse vaccination or prolonging the pulse period is beneficial to epidemic propagation. The topology of complex networks has a non-negligible influence on the epidemic propagation under pulse control, which is demonstrated both theoretically and numerically.

Navigating uncertainty: A dynamic Bayesian network-based risk assessment framework for maritime trade routes

Maritime safety is crucial for international seaborne trade and the global economy. Acknowledging the inevitable and multifaceted risks present in maritime navigation, we introduce a novel approach to evaluate the time-dependent risk performance of various routes, with the objective to mitigate vulnerabilities and fortify resilience. To achieve this goal, we have developed an effective framework using a Dynamic Bayesian network (DBN) model to capture the interactive relationships among the influential factors in probabilistic terms. This framework employs a combination of the synthetic minority over-sampling technique and edited nearest neighbor approach to address the issue of imbalanced maritime accident reports. Furthermore, the gradient descent algorithm is utilized to calculate the conditional probabilities among the influential factors, while the Markov chain model is applied to develop the DBN model. The framework enables dynamical consideration of the risk performance of the maritime trade routes and identifies the key influential factors during different time intervals. Our research scientifically identifies the devastating impact of terrorism on shipping routes, followed by other risk factors such as piracy, military conflicts, and various induced risks, ranked in descending order of severity. The case study on the Indian Ocean shipping route, which applies the proposed methodology, reveals an initial phase of fluctuating increases, succeeded by a prevailing downward trend over the span of 2009–2019. The methodology and results provide valuable support for maritime stakeholders in making informed decisions.

Improved brain effective connectivity modeling by dynamic Bayesian networks

Background:If brain effective connectivity network modelling (ECN) could be accurately achieved, early diagnosis of neurodegenerative diseases would be possible. It has been observed in the literature that Dynamic Bayesian Network (DBN) based methods are more successful than others. However, DBNs have not been applied easily and tested much due to computational complexity problems in structure learning. New method:This study introduces an advanced method for modelling brain ECNs using improved discrete DBN (Improved- dDBN) which addresses the computational challenges previously limiting DBN application, offering solutions that enable accurate and fast structure modeling. Results:The practical data and prior sizes needed for the convergence to the globally correct network structure are proved to be much smaller than the theoretical ones using simulated dDBN data. Besides, Hill Climbing is shown to converge to the true structure at a reasonable iteration step size when the appropriate data and prior sizes are used. Finally, importance of data quantization methods are analysed. Comparison with existing methods:The Improved-dDBN method performs better and robust, when compared to the existing methods for realistic scenarios such as varying graph complexity, various input conditions, noise cases and non-stationary connections. The data used in these tests is the simulated fMRI BOLD time series proposed in the literature. Conclusions:Improved-dDBN is a good candidate to be used on real datasets to accelerate developments in brain ECN modeling and neuroscience. Appropriate data and prior sizes can be identified based on the approach proposed in this study for global and fast convergence.

Sustainable Resilient E-Waste Management in London: A Circular Economy Perspective

The circular economy (CE) is reasoned to organize complex systems supporting sustainable resilience by distinguishing between waste materials and economic growth. This is crucial to the electronic waste (e-waste) industry of developed countries, and e-waste operation management has become their top priority because e-waste contains toxic materials and valuable sources of elements. In the UK, although London Metropolitan city boasts an ambitious sustainable resilience target underlying the context of CE, practical implementation has yet to be feasible, with few investigations detailing if and how the existing target implications enable industrial and social-ecological sectors to continue their performance functionalities in the face of undesired disruptions. In this paper, a dynamic Bayesian Network (dynamic BN) approach is developed to address a range of potential risks. The existing London e-waste operation management is considered as an application of study for sustainable resilience development. Through the utilization of dynamic BN, a comprehensive analysis yields a Resilience Index (RI) of 0.5424, coupled with a StdDev of 0.01350. These metrics offer a profound insight into the intricate workings of a sustainable system and its capacity to swiftly rebound from unexpected shocks and disturbances. This newfound understanding equips policymakers with the knowledge needed to navigate the complexities of sustainable e-waste management effectively. The implications drawn from these in-depth analyses furnish policymakers with invaluable information, enabling them to make judicious decisions that advance the cause of sustainable e-waste management. The findings underscore that the absorptive capacity of a sustainable and resilient e-waste operation management system stands as the foremost defense mechanism against unforeseen challenges. Furthermore, it becomes evident that two pivotal factors, namely “diversifying the supply chain” and “enhancing supply chain transparency,” play pivotal roles in augmenting the sustainability and resilience of e-waste operation management within the context of London’s ambitious sustainability targets. These factors are instrumental in steering the trajectory of e-waste management towards a more sustainable and resilient future, aligning with London’s aspirations for a greener and more eco-conscious future.

Self-healing, adaptive and shape memory polymer-based thermal interface phase change materials via boron ester cross-linking

Addressing the thermal resistance between rough interfaces without applying pressure to the interfacial sandwich has been a challenge. Herein, a thermal interface phase change material (TIPCM) is designed to realize a 3D support skeleton with a dynamic crosslinking network by introducing a boron ester crosslinking backbone into paraffin wax (PW) and ethylene-octene copolymer (EOC), thus enabling the TIPCM to ensure mechanical integrity without leakage even above the melting temperature of EOC. The chemical cross-linking between the organic solid–liquid phase change material (PCM) and the polymer realizes thermally triggered self-healing and adaptive shape memory properties. The phase transition of PW leads to a decrease in the modulus of TIPCM and activates the ester exchange of the dynamic covalent bonding of boron esters, which allows TIPCM to self-heal and self-adapt to a variety of object surfaces. These enabled the TIPCM to fill the interface gaps through small stress deformations, forming an interlocking structure that reduces contact thermal resistance and promotes heat transfer. The obtained TIPCM achieves excellent chip thermal management performance, cooling the analog CPU temperature by 67 °C at 5 V. In conclusion, this study provides a potential strategy for redesigning TIPCMs with high latent heat and special physical properties for thermal management.

TFAN: A task-adaptive feature alignment network for few-shot website fingerprinting attacks on Tor

Few-shot website fingerprinting (WF) attacks aim to infer which website a user browsed through anonymity networks, such as Tor, using limited labeled traces. Recent methods either adopt complex metric strategies or perform time-consuming transfer learning, neither of which yields the most efficient performance in dynamic network environments. In this paper, we introduce a novel Task-adaptive Feature Alignment Network (TFAN) following the meta-learning paradigm. TFAN regards the few-shot WF attack as a feature alignment problem in class latent space, aiming to depict each location in the query feature map as a weighted sum of support features of a given class. Ridge regression provides a closed-form solution without extra parameters or techniques, ensuring high computational efficiency. Moreover, we also propose a Task-adaptive Modulation Unit (TMU), which activates the differences between support prototypes to generate task-level channel weights, making channels with significant discriminative details for each task contribute more to alignment. Extensive experiments on public Tor datasets demonstrate the superiority of TFAN in different scenarios. Notably, it is the only method that maintains over 90% accuracy in the 1-shot setting even 42 days later. Our code is available at https://github.com/Crybaby98/TFAN.

Spontaneous recovery in random hypergraphs.

In many real-world phenomena, such as the reconstruction of disaster areas after an earthquake or the stock market's recovery after an economic crisis, damaged networks are spontaneously active after receiving assistance. To reveal how the recovery process, the research of dynamic network recovery has become a hot topic in the field of network science. Previous studies on network recovery have been limited to simple networks with pairwise interactions. However, real-world systems are usually networks with higher-order interactions that are composed of multiple units. To better understand the recovery phenomenon on complex networks in the real world, we propose a novel spontaneous recovery model applied to hypergraphs. The model considers two types of recovery, internal recovery and fast recovery, where inactive nodes in the network can either recover internally with independent probabilities or receive sufficient resources from the hyperedge for fast recovery. We find that the number of active nodes in the system shows a phase change from continuous to discontinuous as the fast recovery condition is relaxed. Moreover, under the influence of higher-order interactions, increasing both average hyperedge cardinality and network heterogeneity contribute to increasing the network resilience. These findings help us understand the recovery mechanisms of complex networks and provide essential insights into designing highly resilient systems.

TITE: A transformer-based deep reinforcement learning approach for traffic engineering in hybrid SDN with dynamic traffic

Hybrid Software Defined Networks (Hybrid SDNs), with a partial upgrade of legacy routers to SDN switches in traditional distributed networks, currently stand as a prevailing network architecture. Traffic Engineering (TE) in hybrid SDN requires the efficient and timely acquisition of a routing policy to adapt to dynamically changing traffic demands, which has recently become a hot topic. Ignoring the hidden relations of consecutive states and the compact representation of the network environment, previous Deep Reinforcement Learning (DRL)-based studies suffer from the convergence problem by only establishing the direct relationship between individual Traffic Matrix (TM) and routing policy. Therefore, to enhance TE performance in hybrid SDNs under dynamically changing traffic demands, we propose to integrate the Transformer model with DRL to establish the relationship between consecutive states and routing policies. The temporal characteristic among consecutive states can effectively assist DRL in solving the convergence problem. To obtain a compact and accurate description of the network environment, we propose to jointly consider TM, routing action, and reward in designing the state of the network environment. To better capture the temporal relations among consecutive states of the network environment, we design a multi-feature embedding module and achieve positional encodings in the Transformer model. The extensive experiments demonstrate that once the convergence problem is solved, the proposed Transformer-based DRL method can efficiently generate routing policies that adapt well to dynamic network traffic.

Finite/fixed-time cluster synchronization for directed and multiplex coupled dynamic networks

This article deals with finite/fixed-time cluster synchronization (FnTCS/FdTCS) issue for directed and multiplex coupled dynamic networks (MCDNs). Finite/fixed-time synchronization of multiplex networks has become a popular research topic, which indicates that, state information is utilized for synchronization, and the settling time depends on original condition for a range of finite time, while the time is bounded with arbitrary original value for fixed-time one. Through constructing appropriate feedback control protocol, FnTCS and FdTCS matters for MCDNs are settled under re-arranging variables' order technique. The present model contains the case that outer matrices (OMs) can be directed, with competitive elements, and not even connected, while previous and related researches assumed that OMs were undirected, cooperative and connected, so existing results can be improved for more general and broader regulations. This strategy above is presented to solve directed CDNs with multiweights from angle of inner and outer matrices, and we prove that if the weighted group of added OMs for each dimension is strongly connected, then cluster synchronization rules are established in finite/fixed time. Moreover, we also earn finite/fixed-time synchronization criteria when the cluster is single. In addition, the issue of FnTCS/FdTCS is developed for directed and multiplex coupled reaction-diffusion networks (MCRDNs) as an application. The validity of these gained results is verified by simulated examples.

A reliable connection-aware routing protocol for underwater wireless sensor networks

Underwater Acoustic Sensor Networks (UASNs) have gained significant popularity and application in various marine engineering exploration scenarios, driven by the global evolution of the ocean ecosystem. However, UASNs face numerous challenges arising from the unique characteristics of the underwater environment and acoustic channels, such as limited energy resources, unreliable communication, and dynamic network topology in uncertain environments, all of which impact the network lifetime and transmission reliability. To address these challenges and enable efficient underwater data packet transmissions, this paper proposes a reliable connection-aware routing method called RCRP. The RCRP organizes sensor nodes into clusters, where cluster heads transmit the fused data to the sink node through multi-hop forwarding. To overcome routing voids caused by node failures during packet transmission, a prediction model based on the Markov chain is introduced to identify void nodes and inform neighboring nodes about the routing holes. Furthermore, a connection prediction mechanism is developed to tackle changes in the uncertain network topology, taking into account node mobility and the received SNR. For packet transmissions, a waiting mechanism inspired by the opportunistic routing (OR) paradigm is proposed, which determines the optimal forwarding route based on the calculated probability of successful connection between nodes. Simulation results demonstrate that RCRP outperforms existing routing protocols in terms of packet delivery ratio, surviving time, and energy consumption, highlighting its effectiveness in enhancing the performance of UASNs.

Time-varying dynamic Bayesian network learning for an fMRI study of emotion processing.

This article presents a novel method for learning time-varying dynamic Bayesian networks. The proposed method breaks down the dynamic Bayesian network learning problem into a sequence of regression inference problems and tackles each problem using the Markov neighborhood regression technique. Notably, the method demonstrates scalability concerning data dimensionality, accommodates time-varying network structure, and naturally handles multi-subject data. The proposed method exhibits consistency and offers superior performance compared to existing methods in terms of estimation accuracy and computational efficiency, as supported by extensive numerical experiments. To showcase its effectiveness, we apply the proposed method to an fMRI study investigating the effective connectivity among various regions of interest (ROIs) during an emotion-processing task. Our findings reveal the pivotal role of the subcortical-cerebellum in emotion processing.

Enhanced Wireless Communication Optimization with Neural Networks, Proximal Policy Optimization and Edge Computing for Latency and Energy Efficiency

This research proposes a novel approach for efficient resource allocation in wireless communication systems. It combines dynamic neural networks, Proximal Policy Optimization (PPO), and Edge Computing Orchestrator (ECO) for latency-aware and energy-efficient resource allocation. The proposed system integrates multiple components, including a dynamic neural network, PPO, ECO, and a Mobile Edge Computing (MEC) server. The experimental methodology involves utilizing the NS-3 simulation platform to assess latency and energy efficiency in resource allocation within a wireless communication network, incorporating an ECO, MEC server, and dynamic task scheduling algorithms. It demonstrates a holistic and adaptable approach to resource allocation in dynamic environments, showcasing a notable reduction in latency for devices and tasks. Latency values range from 5 to 20 milliseconds, with corresponding resource utilization percentages varying between 80% and 95%. Additionally, energy-efficient resource allocation demonstrates a commendable reduction in energy consumption, with measured values ranging from 10 to 30 watts, coupled with efficient resource usage percentages ranging from 70% to 85%. These outcomes validate the efficacy of achieving both latency-aware and energy-efficient resource allocation for enhanced wireless communication systems. The proposed system has broad applications in healthcare, smart cities, IoT, real-time analytics, autonomous vehicles, and augmented reality, offering a valuable solution to optimize energy consumption, reduce latency, and enhance system efficiency in these industries.