Attack graph based evaluation of network security.

Abstract. The perspective directions in evaluating network security are simulating possible malefactor's actions, building the representation of these actions as attack graphs (trees, nets), the subsequent checking of various properties of these graphs, and determining security metrics which can explain possible ways to increase security level. The paper suggests a new approach to security evaluation based on comprehensive simulation of malefactor's actions, construction of attack graphs and computation of different security metrics. The approach is intended for using both at design and exploitation stages of computer networks. The implemented software system is described, and the examples of experiments for analysis of network security level are considered

Understanding Mechanical Properties in Fused Filament Fabrication of Polyether Ether Ketone

Using dynamic mechanical analysis (DMA), we investigate differences in the mechanical properties of a single-filament wall of polyether ether ketone (PEEK) constructed using fused filament fabrication (FFF) under a range of different printing conditions. Since PEEK is a semi-crystalline polymer, we employ a non-isothermal quiescent crystallization model, informed by infrared (IR)-imaging measurements, to understand our findings. We propose that, under typical FFF cooling conditions, the weld region between filaments remains amorphous. In contrast, the core of the filament has increased time above the glass transition temperature allowing for a signifocant crystal fraction to develop. We correlate the predicted crystal fraction to a storage modulus using the Halpin and Kardos model. With only a single model fitting parameter we can make reasonable predictions for the perpendicular and parallel storage moduli measured via DMA over a range of printing conditions. This work provides a foundation for optimising crystallization for the mechanical performance of the FFF printed PEEK