Optimal security hardening on attack tree models of networks: a cost-benefit analysis

Researchers have previously looked into the problem of determining whether a given set of security hardening measures can effectively make a networked system secure. However, system administrators are often faced with a more challenging problem since they have to work within a fixed budget which may be less than the minimum cost of system hardening. An attacker, on the other hand, explores alternative attack scenarios to inflict the maximum damage possible when the security controls are in place, very often rendering the optimality of the controls invalid. In this work, we develop a systematic approach to perform a cost-benefit analysis on the problem of optimal security hardening under such conditions. Using evolutionary paradigms such as multi-objective optimization and competitive co-evolution, we model the attacker-defender interaction as an “arms race”, and explore how security controls can be placed in a network to induce a maximum return on investment.     

Effect of arc current on characteristics of nanocarbons prepared by cryogenic arc discharge method

A variety of nanocarbons (nanohorns, nanoflowers and nanoclusters) could be prepared by arc discharge in cryogenic nitrogen with either graphite–graphite or iron–graphite electrodes manipulated by a strategy of automatic electrode delivering. Based on local thermal equilibrium assumption, magneto-hydrodynamic equations were taken into account for estimating the arc power efficiency of 60–84%, depending on the electrode combination. The effects of arc current on the morphology and yield of nanocarbons were investigated within a range of 75–150 A. Transmission electron microscopic analyses revealed that the synthesized product consisted of single-walled carbon nanohorns and multi-walled carbon nanoflowers with nominal diameters of 100–200 nm when graphite–graphite electrodes were employed but nanoclusters containing Fe nanoparticles inside carbon nanoshells with smaller size of 70–120 nm were mainly synthesized by iron–graphite electrodes subject to arc discharge in cryogenic nitrogen.