302 research outputs found
Improvise, Adapt, Overcome: Dynamic Resiliency Against Unknown Attack Vectors in Microgrid Cybersecurity Games
Cyber-physical microgrids are vulnerable to rootkit attacks that manipulate
system dynamics to create instabilities in the network. Rootkits tend to hide
their access level within microgrid system components to launch sudden attacks
that prey on the slow response time of defenders to manipulate system
trajectory. This problem can be formulated as a multi-stage, non-cooperative,
zero-sum game with the attacker and the defender modeled as opposing players.
To solve the game, this paper proposes a deep reinforcement learning-based
strategy that dynamically identifies rootkit access levels and isolates
incoming manipulations by incorporating changes in the defense plan. A major
advantage of the proposed strategy is its ability to establish resiliency
without altering the physical transmission/distribution network topology,
thereby diminishing potential instability issues. The paper also presents
several simulation results and case studies to demonstrate the operating
mechanism and robustness of the proposed strategy
Digital Twins for Moving Target Defense Validation in AC Microgrids
Cyber-physical microgrids are vulnerable to stealth attacks that can degrade
their stability and operability by performing low-magnitude manipulations in a
coordinated manner. This paper formulates the interactions between CSAs and
microgrid defenders as a non-cooperative, zero-sum game. Additionally, it
presents a hybrid Moving Target Defense (MTD) strategy for distributed
microgrids that can dynamically alter local control gains to achieve resiliency
against Coordinated Stealth Attacks (CSAs). The proposed strategy reduces the
success probability of attack(s) by making system dynamics less predictable.
The framework also identifies and removes malicious injections by modifying
secondary control weights assigned to them. The manipulated signals are
reconstructed using an Artificial Neural Network (ANN)-based Digital Twin (DT)
to preserve stability. To guarantee additional immunity against instability
arising from gain alterations, MTD decisions are also validated (via utility
and best response computations) using the DT before actual implementation. The
DT is also used to find the minimum perturbation that defenders must achieve to
invalidate an attacker's knowledge effectively.Comment: IEEE Energy Conversion Congress and Expo (ECCE) 202
Lost at Sea: Assessment and Evaluation of Rootkit Attacks on Shipboard Microgrids
Increased dependence of the maritime industry on information and
communication networks has made shipboard power systems vulnerable to stealthy
cyber-attacks. One such attack variant, called rootkit, can leverage system
knowledge to hide its presence and allow remotely located malware handlers to
gain complete control of infected subsystems. This paper presents a
comprehensive evaluation of the threat landscape imposed by such attack
variants on Medium Voltage DC (MVDC) shipboard microgrids, including a
discussion of their impact on the overall maritime sector in general, and
provides several simulation results to demonstrate the same. It also analyzes
and presents the actions of possible defense mechanisms, with specific emphasis
on evasion, deception, and detection frameworks, that will help ship operators
and maritime cybersecurity professionals protect their systems from such
attacks.Comment: 2023 IEEE Electric Ship Technologies Symposium (ESTS
Measurement of Free Stream Turbulence: It’s Modeling and Computations
Present research was initiated to study effects of free stream turbulence (FST) on flow instability and transition. Instabilities of some flows have been investigated qualitatively with respect to FST- but scant attention has been paid to compute extrinsic dynamics of flows due to FST. In actual flows, omnipresent background disturbances, e.g. FST triggers transition to turbulence. The motivation for the present work is to characterize and model FST, based on it’s statistics, obtained from wind tunnel and flight test experiments. The developed model is applied to numerically study the receptivity of flow past circular cylinder to the FS
A triad of rhenium-mediated transformations
The title transformations are oxygen atom transfer, twin isomerization and regiospecific imine oxidation.Bispyridyldiazole ligands have furnished new oxygen atom transfer reagents of coordination type ReVOCl3(NN) which undergo a slower transfer to PPh3 than the corresponding azole reagents. The rate of twin isomerization (linkage and geometrical) of meridional azole complexes of coordination type ReIII(OPnP)Cl3(NN) to facial ReIII(PnPO)Cl3(NN) decreases rapidly asn increases in the interval 1-4 (PnP is Ph2P(CH2)nPPh2). An α-diimine chelate of type ReV(NPh)Cl3(NN) is shown to undergo facile oxidation to the corresponding iminoamide complex ReVI(NPh)Cl3(NN) upon treating with dilute nitric acid. The reaction proceeds via regiospecific nucleophilic addition of waterto the more polarized imine function
Cadmium induces lung inflammation independent of lung cell proliferation: a molecular approach
<p>Abstract</p> <p>Background</p> <p>Cadmium is one of the inflammation-related xenobiotics and has been regarded as a potent carcinogen. The relationship between inflammation and cell proliferation due to chronic infection has been studied, but the mechanism is not fully clear. Though the mode of cadmium toxicity is well characterized in animal cells, still it requires some further investigations. Previously we reported that cadmium induces immune cell death in Swiss albino mice. In the present study we showed that instead of inducing cell death mechanism, cadmium in low concentration triggers proliferation in mice lung cell and our results reveals that prior to the induction of proliferation it causes severe inflammation.</p> <p>Methods</p> <p>Swiss albino mice were treated with different concentrations of cadmium to determine the LD50. Mice were subdivided (5 mice each) according to the exposure period (15, 30, 45, 60 days) and were given sub lethal dose (5 mg/Kg body weight) of cadmium chloride and ibuprofen (50 mg/Kg body weight, recommended dose) once in a week. SEM and histology were performed as evidence of changes in cellular morphology. Inflammation was measured by the expression of Cox-2 and MMPs. Expression of proinflammatory cytokines (Cox-2, IL-6), signaling and cell cycle regulatory molecules (STAT3, Akt, CyclinD1) were measured by western blot, ELISA and immunoprecipitation. Mutagenecity was evidenced by comet assay. Cell proliferation was determined by cell count, cell cycle and DNA analysis.</p> <p>Results</p> <p>Prolonged exposure of low concentration of cadmium resulted in up regulation of proinflammatory cytokines and cell cycle regulatory molecules. Though NSAIDs like Ibuprofen reduces the expression of inflammatory cytokines, but it did not show any inhibitory effect on cadmium adopted lung cell proliferation.</p> <p>Conclusion</p> <p>Our results prove that cadmium causes both inflammation and cell proliferation when applied in a low dose but proliferative changes occur independent of inflammation.</p
Bifurcation sequence of two-dimensional Taylor-Green vortex via vortex interactions: Evolution of energy spectrum
The vorticity dynamics of the two-dimensional (2D) Taylor-Green vortex (TGV)
problem is investigated in its multi-cellular configuration by solving the
incompressible Navier-Stokes equation for long time intervals using a
pseudo-spectral method. This helps follow the vorticity dynamics of periodic
free shear layer flows by solving an extremely accurate algorithm to explain
vortex interactions that lead to vortex stripping (forward cascade), merger,
and reconnection (inverse cascade) during various stages of evolution of
periodic arrangements of a large number of TGV vortical cells. This latter
aspect has been adopted so as not to be affected by the periodicity constraints
of a single periodic cell and the various imposed symmetries that attenuate
disturbance growth. The analytic solution of the TGV provides the initial
condition and the spatially accurate Fourier spectral method enables one to
track the first instability of the initial doubly periodic vortices. Despite a
plethora of studies following the primary instability to relate it with
transition to turbulence and the subsequent decay of turbulence in the
literature, the topic of bifurcation sequence for periodic TGV is rare, and
that is one of the main aims of the present research. Instead of restricting
one's attention on a single periodic TGV cell, here it is purposely reported
for multiple cells of the TGV in both directions, without invoking any
asymmetries extraneously. For such an ensemble, one can study various vortical
interactions giving rise to atypical energy spectra, a topic that has also been
seldom addressed to distinguish between successive instabilities that can upon
a conjecture, lead to transition and subsequent relaminarization, versus the
bifurcation sequences leading from one equilibrium state to subsequent ones.
The present study shows the dominance of the latter for 2D TGV at post-critical
Reynolds number
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