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

Effect of Graphite Filler Type on the Thermal Conductivity and Mechanical Behavior of Polysulfone-Based Composites

The goal of this study was to create a high-filled composite material based on polysulfone using various graphite materials. Composite material based on graphite-filled polysulfone was prepared using a solution method which allows the achievement of a high content of fillers up to 70 wt.%. Alongside the analysis of the morphology and structure, the thermal conductivity and mechanical properties of the composites obtained were studied. Structural analysis shows how the type of filler affects the structure of the composites with the appearance of pores in all samples which also has a noticeable effect on composites’ properties. In terms of thermal conductivity, the results show that using natural graphite as a filler gives the best results in thermal conductivity compared to artificial and expanded graphite, with the reduction of thermal conductivity while increasing temperature. Flexural tests show that using artificial graphite as a filler gives the composite material the best mechanical load transfer compared to natural or expanded graphite

Novel carbon fibers reinforced composites based on polysulfone matrix

The aim of this study is to create composites based on the high-temperature polymer reinforced with the carbon fibers and to study interfacial interaction between carbon fibers and polymer matrix. We propose a new method to obtain polysulfone based composite materials reinforced with high-modulus carbon fibers. The influences of thermal oxidation of carbon fibers on mechanical and thermal properties of the composites were studied. It was found that the obtained composite materials have sufficiently high mechanical properties, tensile strength up to 1047 MPa and Young’s modulus up to 70.9 GPa were found. Considerable interest to the polymer composites is associated with their high performance and good mechanical and thermal properties, which enable a broad range of aerospace, automotive and medical applications. Additionally, the manufacturing process of such composites can easily be optimized and automatized, furthermore, it is not time-consuming process in relation with thermosetting polymer based composites