Publications

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Increasingly, cyberspace is the battlefield of choice for twenty first century criminal activity and foreign conflict. This suggests that traditional modeling and simulation approaches have stalled in the information security domain. We propose a game theoretic model based on a multistage model of computer network exploitation (CNE) campaigns comprising reconnaissance, tooling, implant, lateral movement, exfiltration and cleanup stages. In each round of the game, the attacker chooses whether to proceed with the next stage of the campaign, nature decides whether the defender is cognizant of the campaign's progression, and the defender chooses to respond in an active or passive fashion. We propose a dynamic, asymmetric, complete-information, general-sum game to model CNE campaigns and techniques to estimate this game's parameters. Researchers can extend this work to other threat models, and practitioners can use this work for decision support.

Information security is a top priority in government and industry because high consequence cyber incidents continue with regularity. The blue teamers that protect cyber systems cannot stop or even know about all these incidents, so they must take measures to tolerate these incursions in addition to preventing and detecting them. We propose dynamically compartmentalizing subject networks into collaboration zones and limiting the communication between these zones. In this article, we demonstrate this technique's effect on the attacker and the defender for various parameter settings using discrete-time simulation. Based on our results, we conclude that dynamic cyber zone defense is a viable intrusion tolerance technique and should be considered for technology transfer.

The heterogeneity in mechanical fields introduced by microstructure plays a critical role in the localization of deformation. To resolve this incipient stage of failure, it is therefore necessary to incorporate microstructure with sufficient resolution. On the other hand, computational limitations make it infeasible to represent the microstructure in the entire domain at the component scale. In this study, the authors demonstrate the use of concurrent multiscale modeling to incorporate explicit, finely resolved microstructure in a critical region while resolving the smoother mechanical fields outside this region with a coarser discretization to limit computational cost. The microstructural physics is modeled with a high-fidelity model that incorporates anisotropic crystal elasticity and rate-dependent crystal plasticity to simulate the behavior of a stainless steel alloy. The component-scale material behavior is treated with a lower fidelity model incorporating isotropic linear elasticity and rate-independent J2 plasticity. The microstructural and component scale subdomains are modeled concurrently, with coupling via the Schwarz alternating method, which solves boundary-value problems in each subdomain separately and transfers solution information between subdomains via Dirichlet boundary conditions. In this study, the framework is applied to model incipient localization in tensile specimens during necking.

Silsesquioxane nanoparticles are composed of repetitive organosilica fragments in their frameworks and are now recognized to have outstanding functional fertility. Depending on the organosilane and the synthetic pathways, silsesquioxane NPs can be pendant, bridged, dense or porous. Recently the diverse functionalities of mesoporous silsesquioxane nanoparticles have been exploited for the sake of drug-related biomedicine. Fine-tuning the silsesquioxane nanoparticles characteristics allow not only a superior retention capacity of therapeutics without the need of any further modification, but also a controlled release through various environmentally-stimulated triggers. Furthermore, the main focus of the present review is to highlight the different types of silsesquioxane nanoparticles and their exceptional features focused on controlled delivery of drugs, proteins, antibodies and DNA through pH, redox or light stimuli.

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This report describes the status of the development of MELCOR Sodium Chemistry (NAC) package. This development is based on the CONTAIN-LMR sodium physics and chemistry models to be implemented in MELCOR. In the past three years, the sodium equation of state as a working fluid from the nuclear fusion safety research and from the SIMMER code has been implemented into MELCOR. The chemistry models from the CONTAIN-LMR code, such as the spray and pool fire mode ls, have also been implemented into MELCOR. This report describes the implemented models and the issues encountered. Model descriptions and input descriptions are provided. Development testing of the spray and pool fire models is described, including the code-to-code comparison with CONTAIN-LMR. The report ends with an expected timeline for the remaining models to be implemented, such as the atmosphere chemistry, sodium-concrete interactions, and experimental validation tests .

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