The cognitive infrastructureless network has received significant attention to reduce signaling load in next-generation networks, which are expected to be ultradense with very high peak rate but relatively lower expec...
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The cognitive infrastructureless network has received significant attention to reduce signaling load in next-generation networks, which are expected to be ultradense with very high peak rate but relatively lower expected traffic per user. Research in this area has evolved from the distributed algorithms requiring prior knowledge of the number of secondary users (SUs) U to the existing algorithms, which can estimate U independently by counting the number of collisions. The major drawback of these algorithms is the large number of collisions leading to wastage of power and bring down the effective life of battery operated SUs. In this paper, we develop algorithms that learn faster and incurs fewer collisions. We assume unknown U with two types of networks: fixed U (i.e., static networks) and time-varying U (i.e., dynamic networks). Proposed algorithms are based on the multiplayer multi-armed bandit (MAB) approach. We show that the proposed algorithms offer constant regret (i.e., throughput loss) with high probability and sub-linear regret in static and dynamic networks, respectively. Theoretical analysis, simulation, and experimental results demonstrate the efficacy of the proposed algorithms in terms of vacant spectrum utilization, regret, and the number of collisions. Fewer collisions significantly increase the operational life of SUs.
The islanded and network-connected modes are expected to be modeled into a unified form as well as in a distributed fashion for multi-energy system. In this way, the adaptability and flexibility of multi-energy system...
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The islanded and network-connected modes are expected to be modeled into a unified form as well as in a distributed fashion for multi-energy system. In this way, the adaptability and flexibility of multi-energy system can be enhanced. To this aim, this paper establishes a double-mode energy management model for the multi-energy system. It is formed by many energy bodies. With such a model, each participant is able to adaptively respond to the change of mode switching. Furthermore, a novel distributed dynamic event-triggered Newton-Raphson algorithm is proposed to solve the double-mode energy management problem in a fully distributed fashion. In this method, the idea of Newton descent along with the dynamic event-triggered communication strategy are introduced and embedded in the execution of the proposed algorithm. With this effort, each participant can adequately utilize the second-order information to speed up convergence. The optimality is not affected. Meanwhile, the proposed algorithm can be implemented with asynchronous communication and without needing special initialization conditions. It exhibits better flexibility and adaptability especially when the system modes are changed. In addition, the continuous-time algorithm is executed with discrete-time communication driven by the proposed dynamic event-triggered *** results in reduced communication interaction and avoids needing continuous-time information transmission. It is also proved that each participant can asymptotically converge to the global optimal point. Finally, simulation results show the effectiveness of the proposed model and illustrate the faster convergence feature of the proposed algorithm.
Many natural and engineered systems can be modeled as a set of nonlinear units interacting with each other over a network of interconnections. Often, such interactions occur through different types of functions giving...
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Many natural and engineered systems can be modeled as a set of nonlinear units interacting with each other over a network of interconnections. Often, such interactions occur through different types of functions giving rise to so-called multiplex networks. As an example, two masses can interact through both a spring and a damper. In many practical applications, the multiplex network topology is unknown, and global information is not available. In this paper, we propose a novel distributed approach to infer the network topology for a class of networks with both nonlinear node dynamics and multiplex couplings. In our strategy, the estimators measure only local network states but cooperate with their neighbors to fully infer the network topology. Sufficient conditions for stability and convergence are derived using appropriate Lyapunov functions. Applications to networks of chaotic oscillators and multirobot manipulation are presented to validate our theoretical findings and illustrate the effectiveness of our approach.
This article considers predictive control of the jet engine and electrical power distribution system of a more electric aircraft (MEA) with asynchronous distributed controllers. The shafts of the engine spools are mec...
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This article considers predictive control of the jet engine and electrical power distribution system of a more electric aircraft (MEA) with asynchronous distributed controllers. The shafts of the engine spools are mechanically coupled to the electrical generators of the microgrid, linking the dynamics of the two subsystems. As the subsystems and their controllers are designed by different entities, the preservation of subsystem privacy must be an integral part of any coordination mechanism and, due to the underlying subsystems having differing time scales in their dynamics, the subsystem control updates are not guaranteed to be synchronized. To address these requirements, a distributed model predictive control (D-MPC) algorithm based on the alternating direction method of multipliers (ADMM) is proposed, which accounts for and exploits the differing control update rates of the engine and power subsystem controllers while preserving privacy. An extension to the Algorithm that seeks to minimize the required communication volume by downsampling the interactions to the rate of the engine time scale is also presented. Simulation results on a high-fidelity nonlinear system model demonstrate that the distributed controllers can outperform a decentralized controller and their performance can match that of a fully centralized controller.
The increased complexity of modern energy network raises the necessity of flexible and reliable methods for smart grid operation. To this end, this article is centered on the economic dispatch problem (EDP) in smart g...
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The increased complexity of modern energy network raises the necessity of flexible and reliable methods for smart grid operation. To this end, this article is centered on the economic dispatch problem (EDP) in smart grids, which aims at scheduling generators to meet the total demand at the minimized cost. This article proposes a fully distributed algorithm to address the EDP over directed networks and takes into account communication delays and noisy gradient observations. In particular, the rescaling gradient technique is introduced in the algorithm design and the implementation of the distributed algorithm only resorts to row-stochastic weight matrices, which allows each generator to locally allocate the weights on the messages received from its in-neighbors. It is proved that the optimal dispatch can be achieved under the assumptions that the nonidentical constant communication delays inflicting on each link are uniformly bounded and the noises embroiled in gradient observation of every generator are bounded variance zero mean. Simulations are provided to validate and testify the effectiveness of the presented algorithm.
In this paper, we consider a network scenario in which agents can evaluate each other according to a score graph that models some physical or social interaction. The goal is to design a distributed protocol, run by th...
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In this paper, we consider a network scenario in which agents can evaluate each other according to a score graph that models some physical or social interaction. The goal is to design a distributed protocol, run by the agents, allowing them to learn their unknown state among a finite set of possible values. We propose a Bayesian framework in which scores and states are associated to probabilistic events with unknown parameters and hyperparameters, respectively. We prove that each agent can learn its state by combining a local Bayesian classifier with a (centralized) Maximum Likelihood (ML) estimator of the parameter-hyperparameter. To overcome the intractability of the ML problem, we provide two relaxed probabilistic models that lead to distributed estimation schemes with affordable complexity. In order to highlight the appropriateness of the proposed relaxations, we demonstrate the distributed estimators on a machine-to-machine testing setup for anomaly detection and on a social interaction setup for user profiling.
In this study a new algorithm is proposed for distributed blind sensor macro-calibration in networked control systems robust to noise. The proposed distributed algorithm for estimation of gain and offset correction pa...
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In this study a new algorithm is proposed for distributed blind sensor macro-calibration in networked control systems robust to noise. The proposed distributed algorithm for estimation of gain and offset correction parameters is of stochastic approximation type, with local non-linear transformations of residuals. Convergence of the algorithm in mean-square and with probability one to consensus is proved for a large class of non-linear transformations, network properties and communication and measurement noise characteristics. The choice of the introduced non-linear transformations in accordance with the theory of robust statistics leads to the proposal of new calibration algorithms robustified w.r.t. noise. It is demonstrated by Monte Carlo simulation that the proposed algorithms are very efficient in the presence of large outliers from the point of view of both achievement of high convergence rate and adequate values of convergence points, outperforming the existing linear algorithms.
This paper proposes a distributed adaptive robust voltage/var control (DAR-VVC) method in active distribution networks to minimize power loss while keeping operating constraints under uncertainties. The DAR-VVC aims t...
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This paper proposes a distributed adaptive robust voltage/var control (DAR-VVC) method in active distribution networks to minimize power loss while keeping operating constraints under uncertainties. The DAR-VVC aims to coordinate on-load tap changers, capacitor banks and PV inverters in multiple operation stages through a distributed algorithm. To improve efficiency of the distributed algorithm, an affinity propagation clustering algorithm is employed to divide the distribution network by aggregating "the close nodes" together and setting "the far nodes" apart, leading to the network partition where the information exchange between adjacent sub-networks is reduced. Moreover, the virtual load which describes load characteristics of the sub-networks is applied to enhance the boundary conditions. To fully deal with the uncertainties, the proposed DAR-VVC is formulated in a robust optimization model which considers the worst case to guarantee solution robustness against uncertainty realization. Besides, this paper develops an alternating optimization procedure integrating a column-and-constraint generation algorithm and an alternating direction method of multipliers to solve the DAR-VVC problem. The proposed approach is tested on IEEE 33 and IEEE 123 bus distribution test system and numerical simulations verify high efficiency and full solution robustness of the DAR-VVC.
This study focuses on future distribution networks featuring the integration of extra-high distributed energy resources (DERs). In these distribution networks, the extra-high DER penetration and the randomness and vol...
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This study focuses on future distribution networks featuring the integration of extra-high distributed energy resources (DERs). In these distribution networks, the extra-high DER penetration and the randomness and volatility of DER outputs increase the likelihood of voltage problems. Hence, it is necessary to design efficient solutions for DER output setpoints to regulate the voltages of distribution networks. However, the existing online distributed algorithms were designed based on different linearised technologies for power flow equations, which will cause imprecise results under extra-high DER integration. In this study, the authors propose an increment-correction method to improve the linearised power flow model. To obtain an efficient distributed manner, they introduced an indirect function into the end-customer (the DER owner)'s objective function, stimulating them to provide voltage-regulating service. In particular, two price incentive signals contained in the indirect function were transmitted from the distribution system operator to drive the DER owner to regulate output increments, which is suitable for cases where the DER belongs to different end-customers. The proposed method can not only protect the private information of end-customers but also enhance the robustness of the distribution network for the DER integration level. Numerical test results demonstrate the merits of the proposed method.
In this article, we study the problem of summation evaluation of secrets. The secrets are distributed over a network of nodes that form a ring graph. Privacy-preserving iterative protocols for computing the sum of the...
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In this article, we study the problem of summation evaluation of secrets. The secrets are distributed over a network of nodes that form a ring graph. Privacy-preserving iterative protocols for computing the sum of the secrets are proposed, which are resilient against dynamic node join and leave situations. Theoretic bounds are derived regarding the utility and accuracy, and the proposed protocols are shown to comply with differential privacy requirements. Based on utility, accuracy, and privacy, we also provide guidance on appropriate selections of random noise parameters. Additionally, a few numerical examples that demonstrate their effectiveness and superiority are provided.
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