75,264 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
Expert System for UNIX System Reliability and Availability Enhancement
Highly reliable and available systems are critical to the airline industry. However, most off-the-shelf computer operating systems and hardware do not have built-in fault tolerant mechanisms, the UNIX workstation is one example. In this research effort, we have developed a rule-based Expert System (ES) to monitor, command, and control a UNIX workstation system with hot-standby redundancy. The ES on each workstation acts as an on-line system administrator to diagnose, report, correct, and prevent certain types of hardware and software failures. If a primary station is approaching failure, the ES coordinates the switch-over to a hot-standby secondary workstation. The goal is to discover and solve certain fatal problems early enough to prevent complete system failure from occurring and therefore to enhance system reliability and availability. Test results show that the ES can diagnose all targeted faulty scenarios and take desired actions in a consistent manner regardless of the sequence of the faults. The ES can perform designated system administration tasks about ten times faster than an experienced human operator. Compared with a single workstation system, our hot-standby redundancy system downtime is predicted to be reduced by more than 50 percent by using the ES to command and control the system
EPR spectrum via entangled states for an Exchange-Coupled Dimer of Single-Molecule Magnets
Multi-high-frequency electron paramagnetic resonance(EPR) spectrum for a
supermolecular dimer of single-molecule magnets recently reported
[S. Hill, R. S. Edwards, N. Aliaga-Alcalde and G. Christou(HEAC), Science 302,
1015 (2003)] is studied in terms of the perturbation method in which the
high-order corrections to the level splittings of degenerate states are
included. It is shown that the corresponding eigenvectors are composed of
entangled states of two molecules. The EPR-peak positions are calculated in
terms of the eigenstates at various frequencies.
From the best fit of theoretical level splittings with the measured values we
obtain the anisotropy constant and exchange coupling which are in agreement
with the corresponding values of experimental observation. Our study confirms
the prediction of HEAC that the two units within the dimer are coupled
quantum mechanically by the antiferromagnetic exchange interaction and the
supermolecular dimer behaviors in analogy with artificially fabricated quantum
dots.Comment: 16 pages,2 figures, 2 table
Thermoelectric efficiency at maximum power in low-dimensional systems
Low-dimensional electronic systems in thermoelectrics have the potential to
achieve high thermal-to-electric energy conversion efficiency. A key measure of
performance is the efficiency when the device is operated under maximum power
conditions. Here we study the efficiency at maximum power of three
low-dimensional, thermoelectric systems: a zero-dimensional quantum dot (QD)
with a Lorentzian transmission resonance of finite width, a one-dimensional
(1D) ballistic conductor, and a thermionic (TI) power generator formed by a
two-dimensional energy barrier. In all three systems, the efficiency at maximum
power is independent of temperature, and in each case a careful tuning of
relevant energies is required to achieve maximal performance. We find that
quantum dots perform relatively poorly under maximum power conditions, with
relatively low efficiency and small power throughput. Ideal one-dimensional
conductors offer the highest efficiency at maximum power (36% of the Carnot
efficiency). Whether 1D or TI systems achieve the larger maximum power output
depends on temperature and area filling factor. These results are also
discussed in the context of the traditional figure of merit
The nature of symmetric instability and its similarity to convective and inertial instability
It is shown that there exists a local similarity among SI (Symmetric Instability), BI (Buoyancy or Convective Instability), and II (Inertial Instability) even for fully nonlinear viscous motion. The most unstable slope angles for SI and Moist SI motions are analyzed based on parcel energetics. These considerations also suggest qualitatively that CSI (Conditional SI) circulations will be slantwise and lie between the moist most unstable slope and dry least stable slope of the basic state
Hawking Radiation of an Arbitrarily Accelerating Kinnersley Black Hole: Spin-Acceleration Coupling Effect
The Hawking radiation of Weyl neutrinos in an arbitrarily accelerating
Kinnersley black hole is investigated by using a method of the generalized
tortoise coordinate transformation. Both the location and temperature of the
event horizon depend on the time and on the angles. They coincide with previous
results, but the thermal radiation spectrum of massless spinor particles
displays a kind of spin-acceleration coupling effect.Comment: 8 pages, no figure, revtex 4.0, revisted version with typesetting
errors and misprint correcte
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