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36th IEEE/IFIP network Operations and Management Symposium, NOMS 2023

作者： Hammar, Kim Stadler, Rolf Division of Network and Systems Engineering Kth Royal Institute of Technology Sweden

ISBN: (纸本)9781665477161

We present a novel emulation system for creating high-fidelity digital twins of IT infrastructures. The digital twins replicate key functionality of the corresponding infrastructures and allow to play out security scenarios in a safe environment. We show that this capability can be used to automate the process of finding effective security policies for a target infrastructure. In our approach, a digital twin of the target infrastructure is used to run security scenarios and collect data. The collected data is then used to instantiate simulations of Markov decision processes and learn effective policies through reinforcement learning, whose performances are validated in the digital twin. This closed-loop learning process executes iteratively and provides continuously evolving and improving security policies. We apply our approach to an intrusion response scenario. Our results show that the digital twin provides the necessary evaluative feedback to learn near-optimal intrusion response policies. © 2023 IEEE.

关键词： network security

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Cache Allocation in Multi-Tenant Edge Computing: An Online Model-Based Reinforcement Learning Approach

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IEEE Transactions on Cloud Computing 2025年第2期13卷 459-472页

作者： Ben-Ameur, Ayoub Araldo, Andrea Chahed, Tijani Dán, György Institut Polytechnique de Paris SAMOVAR Telecom SudParis Palaiseau91120 France KTH Royal Institute of Technology Division of Network and Systems Engineering School of Electrical Engineering and Computer Science Stockholm11428 Sweden

We consider a network Operator (NO) that owns Edge Computing (EC) resources, virtualizes them and lets third party Service Providers (SPs) run their services, using the allocated slice of resources. We focus on one specific resource, i.e., cache space, and on the problem of how to allocate it among several SPs in order to minimize the backhaul traffic. Due to confidentiality guarantees, the NO cannot observe the nature of the traffic of SPs, which is encrypted. Allocation decisions are thus challenging, since they must be taken solely based on observed monitoring information. Another challenge is that not all the traffic is cacheable. We propose a data-driven cache allocation strategy, based on Reinforcement Learning (RL). Unlike most RL applications, in which the decision policy is learned offline on a simulator, we assume no previous knowledge is available to build such a simulator. We thus apply RL in an online fashion, i.e., the model and the policy are learned by directly perturbing and monitoring the actual system. Since perturbations generate spurious traffic, we thus need to limit perturbations. This requires learning to be extremely efficient. To this aim, we devise a strategy that learns an approximation of the cost function, while interacting with the system. We then use such an approximation in a Model-Based RL (MB-RL) to speed up convergence. We prove analytically that our strategy brings cache allocation boundedly close to the optimum and stably remains in such an allocation. We show in simulations that such convergence is obtained within few minutes. We also study its fairness, its sensitivity to several scenario characteristics and compare it with a method from the state-of-the-art. © 2013 IEEE.

关键词： Contrastive Learning

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Estimating Time-To-Compromise for Industrial Control System Attack Techniques Through Vulnerability Data

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SN Computer Science 2023年第3期4卷 1-11页

作者： Rencelj Ling, Engla Ekstedt, Mathias Division of Network and Systems Engineering KTH Royal Institute of Technology Teknikringen 33 Stockholm 100 44 Sweden

When protecting the Industrial Control systems against cyber attacks, it is important to have as much information as possible to allocate defensive resources properly. In this paper we estimate the Time-To-Compromise of different Industrial Control systems attack techniques by MITRE ATT&CK. The Time-To-Compromise is estimated using an equation that takes into consideration the vulnerability data that exists for a specific asset and category of vulnerability. The vulnerability data is derived from an Industrial Control systems specific vulnerability dataset. As a result, we present the mapping of the attack techniques to assets and categories of vulnerability, which makes it possible to apply specific vulnerabilities to the technique. We also present the method of how to estimate the Time-To-Compromise of the techniques and finally the values of Time-To-Compromise. After mapping the attack techniques to assets and category of vulnerability we are able to estimate the Time-To-Compromise and discuss its trustworthiness. © 2023, The Author(s).

关键词： Attack techniques Cyber security Industrial control systems MITRE ATT&CK Time-To-Compromise Vulnerability data

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Conjectural Online Learning with First-order Beliefs in Asymmetric Information Stochastic Games 63

Conjectural Online Learning with First-order Beliefs in Asym...

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63rd IEEE Conference on Decision and Control, CDC 2024

作者： Li, Tao Hammar, Kim Stadler, Rolf Zhu, Quanyan New York University Department of Electrical and Computer Engineering United States Kth Royal Institute of Technology Division of Network and Systems Engineering Sweden

ISBN: (纸本)9798350316339

Asymmetric information stochastic games (AISGs) arise in many complex socio-technical systems, such as cyberphysical systems and IT infrastructures. Existing computational methods for AISGs are primarily offline and can not adapt to equilibrium deviations. Further, current methods are limited to particular information structures to avoid belief hierarchies. Considering these limitations, we propose conjectural online learning (COL), an online learning method under generic information structures in AISGs. COL uses a forecaster-actorcritic (FAC) architecture, where subjective forecasts are used to conjecture the opponents' strategies within a lookahead horizon, and Bayesian learning is used to calibrate the conjectures. To adapt strategies to nonstationary environments based on information feedback, COL uses online rollout with cost function approximation (actor-critic). We prove that the conjectures produced by COL are asymptotically consistent with the information feedback in the sense of a relaxed Bayesian consistency. We also prove that the empirical strategy profile induced by COL converges to the Berk-Nash equilibrium, a solution concept characterizing rationality under subjectivity. Experimental results from an intrusion response use case demonstrate COL's faster convergence over state-of-the-art reinforcement learning methods against nonstationary attacks. © 2024 IEEE.

关键词： Cost functions

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An Efficient Method to Estimate Admittance of Black-boxed Inverter-based Resources for Varying Operating Points

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CSEE Journal of Power and Energy systems 2024年第1期10卷 421-426页

作者： Weihua Zhou Bin Liu Nabil Mohammed Behrooz Bahrani Department of Electrical and Computer Systems Engineering Monash UniversityMelbourne 3800Australia Energy Centre Commonwealth Scientific and Industrial Research Organisation(CSIRO)Newcastle 2300Australia.He is now with the Network Planning DivisionTransgridSydney 2000Australia

Traditional analytical approaches for stability assessment of inverter-based resources(IBRs),often requiring detailed knowledge of IBR internals,become impractical due to IBRs’proprietary *** measurements,relying on electromagnetic transient simulation or laboratory settings,are not only time-intensive but also operationally inflexible,since various non-linear control loops make IBRs’admittance models operating-point ***,such admittance measurements must be performed repeatedly when operating point *** avoid time-consuming and cumbersome measurements,admittance estimation for arbitrary operating points is highly ***,existing admittance estimation algorithms usually face challenges in versatility,data demands,and *** this challenge,this letter presents a simple and efficient admittance estimation method for blackboxed IBRs,by utilizing a minimal set of seven operating points to solve a homogeneous linear equation *** studies demonstrate this proposed method ensures high accuracy across various types of *** accuracy is satisfying even when non-negligible measurement errors exist.

关键词： Admittance estimation black box inverterbased resource measurement error operating point

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RIS-Assisted UAV-Enabled JSAC System: Joint Radio Resource and Phase Shift Optimization Framework

RIS-Assisted UAV-Enabled JSAC System: Joint Radio Resource a...

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2023 IEEE Globecom Workshops, GC Wkshps 2023

作者： Tun, Yan Kyaw Dán, György School of Electrical Engineering and Computer Science Kth Royal Institute of Technology Division of Network and Systems Engineering Stockholm Sweden

ISBN: (纸本)9798350370218

We propose a reconfigurable intelligent surface (RIS)-assisted unmanned aerial vehicle (UAV)-enabled joint communication and sensing (JSAC) system in which multiple JSAC nodes equipped with both sensing and communication functions are deployed to perform sensing and communication simultaneously, and a communication-enabled RIS is installed to provide strong wireless links for JSAC nodes to communicate with the UAV (i.e., aerial base station). We then formulate the problem of maximizing the sum communication rate of JSAC nodes while ensuring their minimum sensing performance requirements, i.e., minimum estimation rate requirements, by jointly optimizing sub-band assignment, adaptive bandwidth allocation, and the RIS phase shift. The resulting problem is a mixed-integer nonlinear programming (MILP) problem with a non-convex structure, thus, to solve the problem efficiently, we decompose the problem into two coupled sub-problems, a sub-band assignment and adaptive bandwidth allocation problem, and a RIS phase shift problem. We propose a low-complexity iterative algorithm for solving the sub-problems in an alternating manner. Extensive simulations show that the proposed algorithm can increase the communication rate by up to 27.51 %,48.747%, and 62.0942% compared to RSA, RPS, and RSRPS schemes. © 2023 IEEE.

关键词： dual decomposition Joint sensing and communication one-to-one matching game reconfigurable intelligent surface unmanned aerial vehicle whale optimization

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Adversarial Robustness of Multi-agent Reinforcement Learning Secondary Control of Islanded Inverter-based AC Microgrids 14

Adversarial Robustness of Multi-agent Reinforcement Learning...

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14th IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids, SmartGridComm 2023

作者： Shereen, Ezzeldin Kazari, Kiarash Dan, Gyorgy Kth Royal Institute of Technology Division of Network and Systems Engineering School of Electrical Engineering and Computer Science Stockholm Sweden

ISBN: (纸本)9781665455541

Secondary control of voltage magnitude and frequency is essential to the stable and secure operation of microgrids (MGs). Recent years have witnessed an increasing interest in developing secondary controllers based on multi-agent reinforcement learning (MARL), in order to replace existing model-based controllers. Nonetheless, unlike the vulnerabilities of model-based controllers, the vulnerability of MARLbased MG secondary controllers has so far not been addressed. In this paper, we investigate the vulnerability of MARL controllers to false data injection attacks (FDIAs). Based on a formulation of MG secondary control as a partially observable stochastic game (POSG), we propose to formulate the problem of computing FDIAs as a partially observable Markov decision process (POMDP), and we use state-of-the-art RL algorithms for solving the resulting problem. Based on extensive simulations of a MG with 4 distributed generators (DGs), our results show that MARL-based secondary controllers are more resilient to FDIAs compared to state of the art model-based controllers, both in terms of attack impact and in terms of the effort needed for computing impactful attacks. Our results can serve as additional arguments for employing MARL in future MG control. © 2023 IEEE.

关键词： Controllers

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Procedural Generation of Communication networks in Power systems

arXiv

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arXiv 2024年

作者： Weiss, Xavier Nordström, Lars Hilber, Patrik Süren, Emre Division of Electric Power and Energy Systems KTH Sweden Division of Electromagnetic Engineering and Fusion Science KTH Sweden Division of Network and Systems Engineering Sweden

Power system communication networks enable operators to remotely monitor and control field equipment. The sophistication of these networks is also increasing as operators continue the trend towards digitization, which is beneficial in integrating distributed energy resources. However, as the attack surface increases in size so too does the risk of cyberattacks. The topology, configuration and composition of communication networks is therefore confidential since this can provide information to attackers. As a result, the number of benchmarks available for research purposes is limited. A tool for procedurally generating communication network topologies is therefore proposed. While primarily intended as an enabler for public research into communication networks, this tool also allows general insights to be gained into the effect of communication network design on the vulnerability of networks to cyberattacks. The tool includes the ability to encapsulate network characteristics in JSON specification files, which is demonstrated with example Advanced Metering Infrastructure (AMI), Supervisory Control and Data Acquisition (SCADA) and Wide Area Monitoring (WAM) specification files. The SCADA network generation is then compared to a real-world case. Finally, the effect of network redundancy on the networks’ cyber resilience is investigated. © 2024, CC BY.

关键词： SCADA systems

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Preemies: Anthropometry and Body Shape Models

Preemies: Anthropometry and Body Shape Models

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2024 International Research Council on the Biomechanics of Injury, IRCOBI 2024

作者： Brolin, Karin Brooks, Sarah Alvarez, Victor Chen, Siyuan Zimmer, Pia Brandberg, August Huber-Dangl, Florentine Li, Xiaogai Kleiven, Svein Visvikis, Costandinos Lightness by Design Stockholm Sweden Northern Neonatal Network United Kingdom CYBEX GmbH London United Kingdom Vienna Austria Division of Neuronic Engineering Department of Biomedical Engineering and Health Systems KTH Stockholm Sweden

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Development of 30 kW-Class X-Band Solid State Power Amplifier for the Misasa Deep Space Station

NEC Technical Journal

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NEC Technical Journal 2021年第1期16卷 158-161页

作者： Nakahara, Toshihaya Yamada, Youhei Otake, Toshiya Asao, Hiroyuki Izukura, Kenji Kohigashi, Kousuke Space Systems Division Japan Radio & Sensor Engineering Department Technology Development Division NEC Network and Sensor Systems Ltd Japan Radio & Sensor Engineering Department Technology Development Division Japan Structural Design Engineering Department Technology Development Division NEC Network and Sensor SystemsLtd Japan

Under contract with the Japan Aerospace Exploration Agency (JAXA), NEC Corporation has delivered a 30 kW-class X-band solid state power amplifier to the Misasa Deep Space Station (Ground station for deep space exploration and telecommunication: GREAT) located in Saku City, Nagano Prefecture. To date, klystrons have been used for the high power X-band transmitters required for deep-space probe operations, but NEC has succeeded in implementing the world’s first X-band solid state power amplifier in the 30 kW-class by multiple-stage combining of power amplification units using domestically produced gallium nitride (GaN) devices. © 2021 NEC Mediaproducts. All rights reserved.

关键词： Gallium nitride

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