39,765 research outputs found
Game Theory Meets Network Security: A Tutorial at ACM CCS
The increasingly pervasive connectivity of today's information systems brings
up new challenges to security. Traditional security has accomplished a long way
toward protecting well-defined goals such as confidentiality, integrity,
availability, and authenticity. However, with the growing sophistication of the
attacks and the complexity of the system, the protection using traditional
methods could be cost-prohibitive. A new perspective and a new theoretical
foundation are needed to understand security from a strategic and
decision-making perspective. Game theory provides a natural framework to
capture the adversarial and defensive interactions between an attacker and a
defender. It provides a quantitative assessment of security, prediction of
security outcomes, and a mechanism design tool that can enable
security-by-design and reverse the attacker's advantage. This tutorial provides
an overview of diverse methodologies from game theory that includes games of
incomplete information, dynamic games, mechanism design theory to offer a
modern theoretic underpinning of a science of cybersecurity. The tutorial will
also discuss open problems and research challenges that the CCS community can
address and contribute with an objective to build a multidisciplinary bridge
between cybersecurity, economics, game and decision theory
Differential space-time block-coded OFDMA for frequency-selective fading channels
Combining differential Alamouti space-time block code (DASTBC) with orthogonal frequency-division multiple access (OFDMA), this paper introduces a multiuser/multirate transmission scheme, which allows full-rate and full-diversity noncoherent communications using two transmit antennas over frequency-selective fading channels. Compared with the existing differential space-time coded OFDM designs, our scheme imposes 10 restrictions on signal constellations, and thus can improve the spectral efficiency by exploiting efficient modulation techniques such as QAM, APSK etc. The main principles of our design are s follows: OFDMA eliminates multiuser interference, and converts multiuser environments to single-user ones; Space-time coding achieves performance improvement by exploiting space diversity available with multiple antennas, no matter whether channel state information is known to the receiver. System performance is evaluated both analytically and with simulations
Modeling of cross-coupling magnetic saturation in signal-injection-based sensorless control of permanent-magnet brushless AC motors
An improved brushless AC motor model is proposed for use in signal-injection-based sensorless control schemes by accounting for cross-coupling magnetic saturation between the - and -axes. The incremental self- and mutual-inductance characteristics are obtained by both finite-element analysis and measurements, and have been successfully used to significantly reduce the error in the rotor position estimation of sensorless control
Compensation for rotor position estimation error due to cross-coupling magnetic saturation in signal injection based sensorless control of PM brushless AC motors
This paper proposes a simple method for reducing the rotor position estimation error caused by cross-coupling magnetic saturation between the d- and q-axes when signal injection based sensorless control is applied to a brushless AC (BLAC) motor. The error in the estimated rotor position, which results when conventional signal injection sensorless control is employed, is analyzed. Based on an improved model of a BLAC motor which accounts for the influence of dq-axis cross-coupling on the high-frequency components of the incremental winding inductances, as deduced by either finite element analysis or from measurements, an improved signal injection based sensorless scheme is proposed. Its effectiveness is demonstrated by measurements on a BLAC motor having an interior permanent magnet rotor
Improved rotor position estimation in extended back-EMF based sensorless PM brushless AC drives with magnetic saliency
An improved extended back-EMF based sensorless control method is proposed for a brushless AC motor equipped with an interior permanent magnet rotor. It accounts for dq-axis cross-coupling magnetic saturation by introducing an apparent mutual winding inductance. The error which results in the estimated rotor position when the influence of cross-coupling magnetic saturation is neglected is analyzed analytically, predicted by finite element analysis, and confirmed experimentally, for various d- and q-axis currents. It is shown that a significant improvement in the accuracy of the rotor position estimation can be achieved by the proposed method, as confirmed by measurements
Improved signal injection based sensorless technique for PM brushless AC drives
The accuracy of rotor position estimation in the conventional signal injection based sensorless control of permanent magnet brushless AC drives depends on the load current. This paper proposes an improved method, which significantly reduces the estimation error by accounting for the cross-coupling effect between the d-and q-axes. The conventional and proposed methods are described and their performance is compared by both simulation and experiment
Analysis of synaptic weight distribution in an Izhikevich network
Izhikevich network is a relatively new neuronal network, which consists of cortical spiking model neurons with axonal conduction delays and spike-timingdependent
plasticity (STDP) with hard bound adaptation. In this work, we use uniform and Gaussian distributions respectively to initialize the weights of all excitatory neurons. After the network undergoes a few minutes of STDP adaptation, we can see that the weights of all synapses in the network, for both initial weight distributions, form a bimodal distribution, and numerically the established distribution presents dynamic stability
An effective ant-colony based routing algorithm for mobile ad-hoc network
An effective Ant-Colony based routing algorithm for mobile ad-hoc network is proposed in this paper. In this routing scheme, each path is marked by path grade, which is calculated from the combination of multiple constrained QoS parameters such as the time delay, packet loss rate and bandwidth, etc. packet routing is decided by the path grade and the queue buffer length of the node. The advantage of this scheme is that it can effectively improve the packet delivery ratio and reduce the end-to-end delay. The simulation results show that our proposed algorithm can improve the packet delivery ratio by 9%-22% and the end-to-end delay can be reduced by 14%-16% as compared with the conventional QAODV and ARA routing schemes
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