5,924 research outputs found
Modelling Complex Dynamics and Distributed Generation of Knowledge with Bacterial-Based Algorithms
This study aimed to test that connected and heterogeneous societies with peer-to-peer (P2P) exchanges are more resilient than centralized and homogeneous ones. In agent-based modeling, agents with bounded rationality interact in a common environment guided by local rules, leading to Complex Adaptive Systems that are named 'artificial societies'. These simplified models of human societies grow from the bottom up in
computational environments and can be used as a laboratory to test some hypotheses. We have demonstrated that in a model based on free interactions among autonomous agents, optimal results emerge by incrementing diversity and decentralization of communication structures, as much as in real societies Internet is leading to the
emergence of improvements in collective intelligence. In order to achieve a real “Knowledge Society”, what we have named a “P2P Society”, it is necessary to increase decentralization and heterogeneity through information policies, distributed communication networks, open e-learning approaches and initiatives like public domain licenses, free software and open data
Robust Energy Consumption Prediction with a Missing Value-Resilient Metaheuristic-based Neural Network in Mobile App Development
Energy consumption is a fundamental concern in mobile application
development, bearing substantial significance for both developers and
end-users. Moreover, it is a critical determinant in the consumer's
decision-making process when considering a smartphone purchase. From the
sustainability perspective, it becomes imperative to explore approaches aimed
at mitigating the energy consumption of mobile devices, given the significant
global consequences arising from the extensive utilisation of billions of
smartphones, which imparts a profound environmental impact. Despite the
existence of various energy-efficient programming practices within the Android
platform, the dominant mobile ecosystem, there remains a need for documented
machine learning-based energy prediction algorithms tailored explicitly for
mobile app development. Hence, the main objective of this research is to
propose a novel neural network-based framework, enhanced by a metaheuristic
approach, to achieve robust energy prediction in the context of mobile app
development. The metaheuristic approach here plays a crucial role in not only
identifying suitable learning algorithms and their corresponding parameters but
also determining the optimal number of layers and neurons within each layer. To
the best of our knowledge, prior studies have yet to employ any metaheuristic
algorithm to address all these hyperparameters simultaneously. Moreover, due to
limitations in accessing certain aspects of a mobile phone, there might be
missing data in the data set, and the proposed framework can handle this. In
addition, we conducted an optimal algorithm selection strategy, employing 13
metaheuristic algorithms, to identify the best algorithm based on accuracy and
resistance to missing values. The comprehensive experiments demonstrate that
our proposed approach yields significant outcomes for energy consumption
prediction.Comment: The paper is submitted to a related journa
Machine Learning for Multimedia Communications
Machine learning is revolutionizing the way multimedia information is processed and transmitted to users. After intensive and powerful training, some impressive efficiency/accuracy improvements have been made all over the transmission pipeline. For example, the high model capacity of the learning-based architectures enables us to accurately model the image and video behavior such that tremendous compression gains can be achieved. Similarly, error concealment, streaming strategy or even user perception modeling have widely benefited from the recent learningoriented developments. However, learning-based algorithms often imply drastic changes to the way data are represented or consumed, meaning that the overall pipeline can be affected even though a subpart of it is optimized. In this paper, we review the recent major advances that have been proposed all across the transmission chain, and we discuss their potential impact and the research challenges that they raise
An Optimized Back Propagation Learning Algorithm with Adaptive Learning Rate
Back Propagation (BP) is commonly used algorithm that optimize the performance of network for training multilayer feed-forward artificial neural networks. However, BP is inherently slow in learning and it sometimes gets trapped at local minima. These problems occur mailnly due to a constant and non-optimum learning rate (a fixed step size) in which the fixed value of learning rate is set to an initial starting value before training patterns for an input layer and an output layer. This fixed learning rate often leads the BP network towrds failure during steepest descent. Therefore to overcome the limitations of BP, this paper introduces an improvement to back propagation gradient descent with adapative learning rate (BPGD-AL) by changing the values of learning rate locally during the learning process. The simulation results on selected benchmark datasets show that the adaptive learning rate significantly improves the learning efficiency of the Back Propagation Algorith
Resilience Enhancement Strategies for Modern Power Systems
The frequency of extreme events (e.g., hurricanes, earthquakes, and floods) and man-made attacks (cyber and physical attacks) has increased dramatically in recent years. These events have severely impacted power systems ranging from long outage times to major equipment (e.g., substations, transmission lines, and power plants) destructions. Also, the massive integration of information and communication technology to power systems has evolved the power systems into what is known as cyber-physical power systems (CPPSs). Although advanced technologies in the cyber layer improve the operation and control of power systems, they introduce additional vulnerabilities to power system performance. This has motivated studying power system resilience evaluation and enhancements methods. Power system resilience can be defined as ``The ability of a system to prepare for, absorb, adapt to, and recover from disruptive events''. Assessing resilience enhancement strategies requires further and deeper investigation because of several reasons. First, enhancing the operational and planning resilience is a mathematically involved problem accompanied with many challenges related to modeling and computation methods. The complexities of the problem increases in CPPSs due to the large number and diverse behavior of system components. Second, a few studies have given attention to the stochastic behavior of extreme events and their accompanied impacts on the system resilience level yielding less realistic modeling and higher resilience level. Also, the correlation between both cyber and physical layers within the context of resilience enhancement require leveraging sophisticated modeling approaches which is still under investigation. Besides, the role of distributed energy resources in planning-based and operational-based resilience enhancements require further investigation. This calls for developing enhancement strategies to improve resilience of power grids against extreme events. This dissertation is divided into four parts as follows. Part I: Proactive strategies: utilizing the available system assets to prepare the power system prior to the occurrence of an extreme event to maintain an acceptable resilience level during a severe event. Various system generation and transmission constraints as well as the spatiotemporal behavior of extreme events should be properly modeled for a feasible proactive enhancement plan. In this part, two proactive strategies are proposed against weather-related extreme events and cyber-induced failure events. First, a generation redispatch strategy is formulated to reduce the amount of load curtailments in transmission systems against hurricanes and wildfires. Also, a defensive islanding strategy is studied to isolate vulnerable system components to cyber failures in distribution systems. Part II: Corrective strategies: remedial actions during an extreme event for improved performance. The negative impacts of extreme weather events can be mitigated, reduced, or even eliminated through corrective strategies. However, the high stochastic nature of resilience-based problem induces further complexities in modeling and providing feasible solutions. In this part, reinforcement learning approaches are leveraged to develop a control-based environment for improved resilience. Three corrective strategies are studied including distribution network reconfiguration, allocating and sizing of distributed energy resources, and dispatching reactive shunt compensators. Part III: Restorative strategies: retain the power service to curtailed loads in a fast and efficient means after a diverse event. In this part, a resilience enhancement strategy is formulated based on dispatching distributed generators for minimal load curtailments and improved restorative behavior. Part IV: Uncertainty quantification: Impacts of uncertainties on modeling and solution accuracy. Though there exist several sources of stochasticity in power systems, this part focuses on random behavior of extreme weather events and the associated impacts on system component failures. First, an assessment framework is studied to evaluate the impacts of ice storms on transmission systems and an evaluation method is developed to quantify the hurricane uncertainties for improved resilience. Additionally, the role of unavailable renewable energy resources on improved system resilience during extreme hurricane events is studied. The methodologies and results provided in this dissertation can be useful for system operators, utilities, and regulators towards enhancing resilience of CPPSs against weather-related and cyber-related extreme events. The work presented in this dissertation also provides potential pathways to leverage existing system assets and resources integrated with recent advanced computational technologies to achieve resilient CPPSs
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