arXiv subjects

Imtiaj Khan

Publications and source records attributed to Imtiaj Khan.

3 recordsLinked to original sources

arXiv2023

Undetectable GPS-Spoofing Attack on Time Series Phasor Measurement Unit Data

The Phasor Measurement Unit (PMU) is an important metering device for smart grid. Like any other Intelligent Electronic Device (IED), PMUs are prone to various types of cyberattacks. However, one form of attack is unique to the PMU, the GPS-spoofing attack, where the time and /or the one second pulse (1 PPS) that enables time synchronization are modified and the measurements are computed using the modified time reference. This article exploits the vulnerability of PMUs in their GPS time synchronization signal. At first, the paper proposes an undetectable gradual GPS-spoofing attack with small incremental angle deviation over time. The angle deviation changes power flow calculation through the branches of the grids, without alerting the System Operator (SO) during off-peak hour. The attacker keeps instigating slow incremental variation in power flow calculation caused by GPS-spoofing relentlessly over a long period of time, with a goal of causing the power flow calculation breach the MVA limit of the branch at peak-hour. The attack is applied by solving a convex optimization criterion at regular time interval, so that after a specific time period the attack vector incurs a significant change in the angle measurements transmitted by the PMU. Secondly, while the attack modifies the angle measurements with GPS-spoofing attack, it ensures the undetectibility of phase angle variation by keeping the attack vector less than attack detection threshold. The proposed attack model is tested with Weighted Least Squared Error (WLSE), Kalman Filtering, and Hankel-matrix based GPS-spoofing attack detection models. Finally, we have proposed a gradient of low-rank approximation of Hankel-matrix based detection method to detect such relentless small incremental GPS-spoofing attack.

eess.SY↗

arXiv2021

Detecting Timing Attack on PMU Data utilizing Unwrapped Phase Angle and Low-Rank Henkel Matrix Properties

Introduction of PMUs to cyber-physical system pro-vides accurate data acquisition, while posing additional risk of being the victim of cyber attack. Both False Data Injection Attack (FDIA) and GPS-spoofing or timing attack can provide malicious data to the cyber system, though these two attacks require different post-attack contingency plan. Thus accurate detection of timing attack and separating it from conventional FDIA has become a very important research area. In this article, a successful detection of timing attack mechanism is proposed. Firstly, a method to distinguish timing attack and FDIA using unwrapped phase angle data is developed. Secondly, utilizing low rank Henkel matrix property to differentiate timing attack from electrical events is also presented. Finally, an experimental validation of proposed model is performed on IEEE 13 bus system using simulated GPS-spoofing attack. It can be observed that the timing attack can increase the rank 1 approximation error of Henkel matrix of unwrapped angles by 700% for 3 sec delay in GPS time-stamp. The rank 1 approximation error is increased by 500% for 2 sec delay and the increase is insignificant for 1sec delay attack. FDIA doesn't show any significant change in the low rank approximation profile of Henkel matrix.

cs.CR↗

arXiv2018

Diameter Optimization for Highest Degree of Ballisticity of Carbon Nanotube Field Effect Transistors

Carbon Nanotube (CNT) is one of the most significant materials for the development of faster and improved performance of nano-scaled transistors. This paper aims at analyzing a trade-off between device performance and device size of CNT based transistor. Acoustic and Optical Phonon scattering along with the elastic scattering lead to the non-ballistic performances of those transistors. The main focus of this work is mainly on finding an optimum diameter to obtain the highest degree of ballisticity from both single-walled and double-walled Carbon Nanotube Field Effect Transistors (CNT-FETs). At first, an n-type single-walled Carbon Nanotube Field Effect Transistor has been considered and the diameter dependence on degree of ballisticity has been simulated. The effects of drain voltage, gate voltage and channel length have been investigated for such characteristics followed by a comparison with double-walled CNT-FET structure. First of all, it has been found that degree of ballisticity along with the optimum diameter increases with the increase of (VDS VGS). The increase of channel length, however, degrades the ballistic performance demanding a higher diameter to reach the optimum point. Finally, it can be concluded that optimum diameter for DWCNT-FET reaches earlier than SWCNT-FET but at lower degree of ballisticity.

physics.app-ph↗