29,020 research outputs found
Revealing the unseen: how to expose cloud usage while protecting user privacy
Cloud users have little visibility into the performance characteristics and utilization of the physical machines underpinning the virtualized cloud resources they use. This uncertainty forces users and researchers to reverse engineer the inner workings of cloud systems in order to understand and optimize the conditions their applications operate. At Massachusetts Open Cloud (MOC), as a public cloud operator, we'd like to expose the utilization of our physical infrastructure to stop this wasteful effort. Mindful that such exposure can be used maliciously for gaining insight into other user's workloads, in this position paper we argue for the need for an approach that balances openness of the cloud overall with privacy for each tenant inside of it. We believe that this approach can be instantiated via a novel combination of several security and privacy technologies. We discuss the potential benefits, implications of transparency for cloud systems and users, and technical challenges/possibilities.Accepted manuscrip
Influence of maneuverability on helicopter combat effectiveness
A computational procedure employing a stochastic learning method in conjunction with dynamic simulation of helicopter flight and weapon system operation was used to derive helicopter maneuvering strategies. The derived strategies maximize either survival or kill probability and are in the form of a feedback control based upon threat visual or warning system cues. Maneuverability parameters implicit in the strategy development include maximum longitudinal acceleration and deceleration, maximum sustained and transient load factor turn rate at forward speed, and maximum pedal turn rate and lateral acceleration at hover. Results are presented in terms of probability of skill for all combat initial conditions for two threat categories
Dynamic network analysis of a target defense differential game with limited observations
In this paper, we study a Target-Attacker-Defender (TAD) differential game
involving one attacker, one target and multiple defenders. We consider two
variations where (a) the attacker and the target have unlimited observation
range and the defenders are visibility constrained (b) only the attacker has
unlimited observation range and the remaining players are visibility
constrained. We model the players' interactions as a dynamic game with
asymmetric information. Here, the visibility constraints of the players induce
a visibility network which encapsulates the visibility information during the
evolution of the game. Based on this observation, we introduce network adapted
feedback or implementable strategies for visibility constrained players. Using
inverse game theory approach we obtain network adapted feedback Nash
equilibrium strategies. We introduce a consistency criterion for selecting a
subset (or refinement) of network adapted feedback Nash strategies, and provide
an optimization based approach for computing them. Finally, we illustrate our
results with numerical experiments.Comment: 8 figure
Defender-assisted Evasion and Pursuit Maneuvers
Motivated by the possibilities afforded by active target defense, a 3-agent pursuit-evasion differential game involving an Attacker/Pursuer, a Target/Evader, and a Defender is considered. The Defender strives to assist the Target by intercepting the Attacker before the latter reaches the Target. A barrier surface in a reduced state space separates the winning regions of the Attacker and Target-Defender team. In this thesis, attention focuses primarily on the Attacker\u27s region of win where, under optimal Attacker play, the Defender cannot preclude the Attacker from capturing the Target. Both optimal and suboptimal strategies are investigated. This thesis uses several methods to breakdown and analyze the 3-player differential game
An Analytic Study of Pursuit Strategies
The Two-on-One pursuit-evasion differential game is revisited where the holonomic players have equal speed, and the two pursuers are endowed with a circular capture range ℓ \u3e 0. Then, the case where the pursuers\u27 capture ranges are unequal, ℓ1 \u3e ℓ2 ≥ 0, is analyzed. In both cases, the state space region where capture is guaranteed is delineated and the optimal feedback strategies are synthesized. Next, pure pursuit is considered whereupon the terminal separation between a pursuer and an equal-speed evader less than the pursuer\u27s capture range ℓ \u3e 0. The case with two pursuers employing pure pursuit is considered, and the conditions for capturability are presented. The pure pursuit strategy is applied to a target-defense scenario and conditions are given that determine if capture of the attacker before he reaches the target is possible. Lastly, three-on-one pursuit-evasion is considered where the three pursuers are initially positioned in a fully symmetric configuration. The evader, situated at the circumcenter of the three pursuers, is slower than the pursuers. We analyze collision course and pure pursuit guidance and provide evidence that conventional strategy for “optimal” evasive maneuver is incorrect
Coordinated Defense Allocation in Reach-Avoid Scenarios with Efficient Online Optimization
In this paper, we present a dual-layer online optimization strategy for
defender robots operating in multiplayer reach-avoid games within general
convex environments. Our goal is to intercept as many attacker robots as
possible without prior knowledge of their strategies. To balance optimality and
efficiency, our approach alternates between coordinating defender coalitions
against individual attackers and allocating coalitions to attackers based on
predicted single-attack coordination outcomes. We develop an online convex
programming technique for single-attack defense coordination, which not only
allows adaptability to joint states but also identifies the maximal region of
initial joint states that guarantees successful attack interception. Our
defense allocation algorithm utilizes a hierarchical iterative method to
approximate integer linear programs with a monotonicity constraint, reducing
computational burden while ensuring enhanced defense performance over time.
Extensive simulations conducted in 2D and 3D environments validate the efficacy
of our approach in comparison to state-of-the-art approaches, and show its
applicability in wheeled mobile robots and quadcopters
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