5 research outputs found
Learning to Customize Network Security Rules
Security is a major concern for organizations who wish to leverage cloud
computing. In order to reduce security vulnerabilities, public cloud providers
offer firewall functionalities. When properly configured, a firewall protects
cloud networks from cyber-attacks. However, proper firewall configuration
requires intimate knowledge of the protected system, high expertise and
on-going maintenance.
As a result, many organizations do not use firewalls effectively, leaving
their cloud resources vulnerable. In this paper, we present a novel supervised
learning method, and prototype, which compute recommendations for firewall
rules. Recommendations are based on sampled network traffic meta-data (NetFlow)
collected from a public cloud provider. Labels are extracted from firewall
configurations deemed to be authored by experts. NetFlow is collected from
network routers, avoiding expensive collection from cloud VMs, as well as
relieving privacy concerns.
The proposed method captures network routines and dependencies between
resources and firewall configuration. The method predicts IPs to be allowed by
the firewall. A grouping algorithm is subsequently used to generate a
manageable number of IP ranges. Each range is a parameter for a firewall rule.
We present results of experiments on real data, showing ROC AUC of 0.92,
compared to 0.58 for an unsupervised baseline. The results prove the hypothesis
that firewall rules can be automatically generated based on router data, and
that an automated method can be effective in blocking a high percentage of
malicious traffic.Comment: 5 pages, 5 figures, one tabl
TiO<sub>2</sub> Nanoparticles Coated with Nitrogen-Doped Amorphous Carbon as Lubricant Additives in Engine Oil
Nanoparticle-dispersed lubricants reduce friction and
wear of tribo-pairs
by providing nanoscale polishing and asperity filling mechanisms.
But these particles also have an adverse effect on the lubrication
due to the agglomeration and poor interaction with the tribo-interface.
Herein, we explore the effect of surface modification of TiO2 nanoparticles on the tribological properties of commercial engine
oil. Surface modifications of TiO2 nanoparticles are done
by coating layers of amorphous carbon and nitrogen-doped amorphous
carbon. Investigations of the tribological properties of surface-modified
TiO2 nanoparticle-dispersed oils show improved performance
due to high dispersibility in engine oil. There is a decrease in the
coefficient of friction by ∼35% and the wear scar diameter
by ∼27% when compared to the base oil. Both a surface roughness
reduction of ∼85% and a wear depth profile reduction of ∼88%
are due to the nanoscale polishing mechanism at the tribo-interface
by nanoparticles. To gain insights of the effects of oil concentration
and ball types on the wear scar diameter, a statistical approach is
employed. The analysis of variance test yields that the different
oil concentrations have a significant effect on the wear scar diameter.
The trends obtained from this statistical test are consistent with
the experimental results. This novel approach opens up exploring advanced
methods of statistical analysis for tribological applications
Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes
We
report an effective approach of utilizing multiwalled carbon
nanotubes (MWCNTs) as an active anode material in sodium ion batteries
by expanding the interlayer distance in a few outer layers of multiwalled
carbon nanotubes. The performance enhancement was investigated using
a density functional tight binding (DFTB) molecular dynamics simulation.
It is found that a sodium atom forms a stable bonding with the partially
expanded MWCNT (PECNT) with the binding energy of −1.50 eV
based on the density functional theory calculation with van der Waals
correction, where a sodium atom is caged between the two carbon hexagons
in the two consecutive MWCNTs. Wave function and charge density analyses
show that this binding is physisorption in nature. This larger exothermic
nature of binding energy favors the stable bonding between the PECNT
and a sodium atom, and thereby, it helps to enhance the electrochemical
performance. In the experimental works, partial opening of the MWCNT
with the expanded interlayer has been designed by the well-known Hummer’s
method. It has been found that the introduction of functional groups
causes a partial opening of the outer few layers of a MWCNT, with
the inner core remaining undisturbed. The enhanced performance is
due to an expanded interlayer of carbon nanotubes, which provide sufficient
active sites for the sodium ions to adsorb as well as to intercalate
into the carbon structure. The PECNT shows a high specific capacity
of 510 mAh g<sup>–1</sup> at a current density of 20 mA g<sup>–1</sup>, which is about 2.3 times the specific capacity obtained
for a pristine MWCNT at the same current density. This specific capacity
is higher when compared to other carbon-based materials. The PECNT
also shows a satisfactory cyclic stability at a current density of
200 mA g<sup>–1</sup> for 100 cycles. Based on our experimental
and theoretical results, an alternative perspective for the storage
of sodium ions in MWCNTs is proposed
Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes
We
report an effective approach of utilizing multiwalled carbon
nanotubes (MWCNTs) as an active anode material in sodium ion batteries
by expanding the interlayer distance in a few outer layers of multiwalled
carbon nanotubes. The performance enhancement was investigated using
a density functional tight binding (DFTB) molecular dynamics simulation.
It is found that a sodium atom forms a stable bonding with the partially
expanded MWCNT (PECNT) with the binding energy of −1.50 eV
based on the density functional theory calculation with van der Waals
correction, where a sodium atom is caged between the two carbon hexagons
in the two consecutive MWCNTs. Wave function and charge density analyses
show that this binding is physisorption in nature. This larger exothermic
nature of binding energy favors the stable bonding between the PECNT
and a sodium atom, and thereby, it helps to enhance the electrochemical
performance. In the experimental works, partial opening of the MWCNT
with the expanded interlayer has been designed by the well-known Hummer’s
method. It has been found that the introduction of functional groups
causes a partial opening of the outer few layers of a MWCNT, with
the inner core remaining undisturbed. The enhanced performance is
due to an expanded interlayer of carbon nanotubes, which provide sufficient
active sites for the sodium ions to adsorb as well as to intercalate
into the carbon structure. The PECNT shows a high specific capacity
of 510 mAh g<sup>–1</sup> at a current density of 20 mA g<sup>–1</sup>, which is about 2.3 times the specific capacity obtained
for a pristine MWCNT at the same current density. This specific capacity
is higher when compared to other carbon-based materials. The PECNT
also shows a satisfactory cyclic stability at a current density of
200 mA g<sup>–1</sup> for 100 cycles. Based on our experimental
and theoretical results, an alternative perspective for the storage
of sodium ions in MWCNTs is proposed
Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes
We
report an effective approach of utilizing multiwalled carbon
nanotubes (MWCNTs) as an active anode material in sodium ion batteries
by expanding the interlayer distance in a few outer layers of multiwalled
carbon nanotubes. The performance enhancement was investigated using
a density functional tight binding (DFTB) molecular dynamics simulation.
It is found that a sodium atom forms a stable bonding with the partially
expanded MWCNT (PECNT) with the binding energy of −1.50 eV
based on the density functional theory calculation with van der Waals
correction, where a sodium atom is caged between the two carbon hexagons
in the two consecutive MWCNTs. Wave function and charge density analyses
show that this binding is physisorption in nature. This larger exothermic
nature of binding energy favors the stable bonding between the PECNT
and a sodium atom, and thereby, it helps to enhance the electrochemical
performance. In the experimental works, partial opening of the MWCNT
with the expanded interlayer has been designed by the well-known Hummer’s
method. It has been found that the introduction of functional groups
causes a partial opening of the outer few layers of a MWCNT, with
the inner core remaining undisturbed. The enhanced performance is
due to an expanded interlayer of carbon nanotubes, which provide sufficient
active sites for the sodium ions to adsorb as well as to intercalate
into the carbon structure. The PECNT shows a high specific capacity
of 510 mAh g<sup>–1</sup> at a current density of 20 mA g<sup>–1</sup>, which is about 2.3 times the specific capacity obtained
for a pristine MWCNT at the same current density. This specific capacity
is higher when compared to other carbon-based materials. The PECNT
also shows a satisfactory cyclic stability at a current density of
200 mA g<sup>–1</sup> for 100 cycles. Based on our experimental
and theoretical results, an alternative perspective for the storage
of sodium ions in MWCNTs is proposed