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21.
Panagiotis Vlachos 《Computer Physics Communications》2009,180(10):1990-1998
We present a general two-player quantum game simulator that can simulate any two-player quantum game described by a 2×2 payoff matrix (two strategy games).The user can determine the payoff matrices for both players, their strategies and the amount of entanglement between their initial strategies. The outputs of the simulator are the expected payoffs of each player as a function of the other player's strategy parameters and the amount of entanglement. The simulator also produces contour plots that divide the strategy spaces of the game in regions in which players can get larger payoffs if they choose to use a quantum strategy against any classical one. We also apply the simulator to two well-known quantum games, the Battle of Sexes and the Chicken game.
Program summary
Program title: Quantum Game Simulator (QGS)Catalogue identifier: AEED_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEED_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 3416No. of bytes in distributed program, including test data, etc.: 583 553Distribution format: tar.gzProgramming language: Matlab R2008a (C)Computer: Any computer that can sufficiently run Matlab R2008aOperating system: Any system that can sufficiently run Matlab R2008aClassification: 4.15Nature of problem: Simulation of two player quantum games described by a payoff matrix.Solution method: The program calculates the matrices that comprise the Eisert setup for quantum games based on the quantum circuit model. There are 5 parameters that can be altered. We define 3 of them as constant. We play the quantum game for all possible values for the other 2 parameters and store the results in a matrix.Unusual features: The software provides an easy way of simulating any two-player quantum games.Running time: Approximately 0.4 sec (Region Feature) and 0.3 sec (Payoff Feature) on a Intel Core 2 Duo GHz with 2 GB of memory under Windows XP. 相似文献22.
Secure authentication features of communication and electronic commerce protocols involve computationally expensive and memory intensive cryptographic operations that have the potential to be turned into denial-of-service (DoS) exploits. Recent proposals attempt to improve DoS resistance by implementing a trade-off between the resources required for the potential victim(s) with the resources used by a prospective attacker. Such improvements have been proposed for the Internet Key Exchange (IKE), the Just Fast Keying (JFK) key agreement protocol and the Secure Sockets Layer (SSL/TLS) protocol. In present article, we introduce probabilistic model checking as an efficient tool-assisted approach for systematically quantifying DoS security threats. We model a security protocol with a fixed network topology using probabilistic specifications for the protocol participants. We attach into the protocol model, a probabilistic attacker model which performs DoS related actions with assigned cost values. The costs for the protocol participants and the attacker reflect the level of some resource expenditure (memory, processing capacity or communication bandwidth) for the associated actions. From the developed model we obtain a Discrete Time Markov Chain (DTMC) via property preserving discrete-time semantics. The DTMC model is verified using the PRISM model checker that produces probabilistic estimates for the analyzed DoS threat. In this way, it is possible to evaluate the level of resource expenditure for the attacker, beyond which the likelihood of widespread attack is reduced and subsequently to compare alternative design considerations for optimal resistance to the analyzed DoS threat. Our approach is validated through the analysis of the Host Identity Protocol (HIP). The HIP base-exchange is seen as a cryptographic key-exchange protocol with special features related to DoS protection. We analyze a serious DoS threat, for which we provide probabilistic estimates, as well as results for the associated attacker and participants' costs. 相似文献
23.
Yiannis Verginadis Antonis Michalas Panagiotis Gouvas Gunther Schiefer Gerald Hübsch Iraklis Paraskakis 《Journal of Grid Computing》2017,15(2):219-234
Enterprises increasingly recognize the compelling economic and operational benefits from virtualizing and pooling IT resources in the cloud. Nevertheless, the significant and valuable transformation of organizations that adopt cloud computing is accompanied by a number of security threats that should be considered. In this paper, we outline significant security challenges presented when migrating to a cloud environment and propose PaaSword – a novel holistic framework that aspires to alleviate these challenges. Specifically, the proposed framework involves a context-aware security model, the necessary policies enforcement mechanism along with a physical distribution, encryption and query middleware. 相似文献
24.
Panagiotis Patrinos Pantelis Sopasakis Haralambos SarimveisAuthor vitae 《Automatica》2011,(9):2016-2022
In this paper, the strictly convex quadratic program (QP) arising in model predictive control (MPC) for constrained linear systems is reformulated as a system of piecewise affine equations. A regularized piecewise smooth Newton method with exact line search on a convex, differentiable, piecewise-quadratic merit function is proposed for the solution of the reformulated problem. The algorithm has considerable merits when applied to MPC over standard active set or interior point algorithms. Its performance is tested and compared against state-of-the-art QP solvers on a series of benchmark problems. The proposed algorithm is orders of magnitudes faster, especially for large-scale problems and long horizons. For example, for the challenging crude distillation unit model of Pannocchia, Rawlings, and Wright (2007) with 252 states, 32 inputs, and 90 outputs, the average running time of the proposed approach is 1.57 ms. 相似文献
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26.
Panagiotis Papadakos Nikos Armenatzoglou Stella Kopidaki Yannis Tzitzikas 《Knowledge and Information Systems》2012,30(3):493-525
Most Web Search Engines (WSEs) are appropriate for focalized search, i.e., they make the assumption that users can accurately
describe their information need using a small sequence of terms. However, as several user studies have shown, a high percentage
of search tasks are exploratory, and focalized search very commonly leads to inadequate interactions and poor results. This
paper proposes exploiting static and dynamically mined metadata for enriching web searching with exploration services. Online results clustering, which is a mining task of dynamic nature since it is based on query-dependent snippets, is useful for providing users with
overviews of the top results and thus allowing them to restrict their focus to the desired parts. On the other hand, the various
static metadata that are available to a search engine (e.g., domain, language, date, and filetype) are commonly exploited only through the
advanced (form-based) search facilities that some WSEs offer (and users rarely use). We propose an approach that combines
both kinds of metadata by adopting the interaction paradigm of dynamic taxonomies and faceted exploration, which allows the users
to restrict their focus gradually using both static and dynamically derived metadata. Special focus is given on the design
and analysis of incremental algorithms for speeding up the exploration process. The experimental evaluation over a real WSE
shows that this combination results to an effective, flexible, and efficient exploration experience. Finally, we report the
results of a user study indicating that this direction is promising in terms of user preference, satisfaction, and effort. 相似文献
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29.
Pantelis N Botsaris Panagiotis D SparisAuthor vitae 《Microprocessors and Microsystems》1997,20(10):182-593
The present paper describes a new design for a microcontrolled three-way catalyst efficiency monitoring system. The system is based on the Motorola 68HC11e2 microprocessor and utilizes the differential signal from a pair of thermocouples installed at the catalyst outlet and inlet sections. This signal is processed in real time using an appropriate statistical algorithm and the corresponding results are compared to experimentally determined limiting values to assess the current state of the catalyst efficiency during driving conditions. The result of this comparison is presented on an LCD display as an A, B, C, or FAIL catalyst condition signal. The system can be readily installed and can operate on new and used cars provided that the type of catalyst used has been experimentally tested to provide the necessary limiting values that characterize its relative levels of efficiency. It can also be reprogrammed and calibrated via a RS232C serial interface. 相似文献
30.
Nael H. El-Farra Author Vitae Author Vitae Panagiotis D. Christofides Author Vitae 《Automatica》2004,40(1):101-110
In this work, a hybrid control scheme, uniting bounded control with model predictive control (MPC), is proposed for the stabilization of linear time-invariant systems with input constraints. The scheme is predicated upon the idea of switching between a model predictive controller, that minimizes a given performance objective subject to constraints, and a bounded controller, for which the region of constrained closed-loop stability is explicitly characterized. Switching laws, implemented by a logic-based supervisor that constantly monitors the plant, are derived to orchestrate the transition between the two controllers in a way that safeguards against any possible instability or infeasibility under MPC, reconciles the stability and optimality properties of both controllers, and guarantees asymptotic closed-loop stability for all initial conditions within the stability region of the bounded controller. The hybrid control scheme is shown to provide, irrespective of the chosen MPC formulation, a safety net for the practical implementation of MPC, for open-loop unstable plants, by providing a priori knowledge, through off-line computations, of a large set of initial conditions for which closed-loop stability is guaranteed. The implementation of the proposed approach is illustrated, through numerical simulations, for an exponentially unstable linear system. 相似文献