National Institute of Technology, Meghalaya

About: National Institute of Technology, Meghalaya is a education organization based out in Shillong, India. It is known for research contribution in the topics: Control theory & Electric power system. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

Reduced Order Sliding Mode Observer for a Class of Linear Systems with Relatively Slower Unmeasured State Variables

Abstract: In this paper, we have designed a new observer utilizing the fact that some class of systems possesses at least one fast varying measured state variable along with some sluggish unmeasured plant state variables. This observer is designed with introducing a new variable which is proportional to the combination of unmeasured state variables and the plant output. A velocity estimation problem with a finite dimensional linear time-invariant model of a brushed permanent magnet DC (PMDC)motor has been considered as a case study. Simulation result shows the effectiveness of the proposed reduced order sliding mode observer over the widely used Utkin observer.

Impact Analysis of Cyber Attack under Stable State of Power System: Voltage Stability

Abstract: Smart grids offer improved environmental performance along with increased resilience; however, they are susceptible to a wide range of cyber attacks owing to the wide communication network deployed. In this paper, two cyber attack models are proposed based on bus voltage magnitude and angle which can be realized through available cyber attacks. Simulations are performed on IEEE 9 bus test system to compute steady state voltage stability limit i.e. L index to analyse the impact of proposed cyber attack models at each bus using Siemens PSS/E and MATLAB softwares. Further, a cyber attack constant (CAC) is proposed to mislead the system state data which an attacker may utilize. The results of above work reveal that the proposed cyber attack models may initiate false corrective actions by energy management center (EMC) operator. Thus, the idea of proposed work can support the EMC operator for intelligent corrective actions during cyber attacks in the smart electric grid.

On the Implementation of Multi-bit Inexact Adder Cells and Application towards Image De-noising

Abstract: Inexact computing is an attractive concept for digital signal processing at the submicron regime. This paper proposes 2-bit inexact adder cell and further escalate to 4-bit, and 8-bit inexact adder and error metrics have been evaluated mathematically for such adder cells. The approximated design has been proposed through the simplification of the K-Maps, which leads to a substantial reduction in the propagation delay as well as energy consumption. The proposed design has been verified through the Cadence Spectre and performance parameters (such as delay, power consumption) have been evaluated through CMOS gpdk45 nm technology. Furthermore, the proposed design has been applied to image de-noising application where the performance of the images like Peak Signal to Noise Ratio (PSNR), Normalized Correlation Coefficient (NCC) and Structural Similarity Index (SSIM) has been analyzed through MATLAB, which offer the substantial improvement from its counterpart.

FPGA-based Real-time Performance Analysis of Buck-regulator Fed Current Source Inverter

Abstract: This paper presents an advanced buck-regulator fed current source inverter and the performance analysis of the same is compared with conventional voltage source inverter (VSI) and current source inverter (CSI). In many applications such as brushless dc motors and stepper motors, a square or modified square wave ripple free current for certain period of time is required. However, with pulse width modulation (PWM) voltages and currents obtained at the output of conventional VSI and CSI contains harmonics. A buck-regulator fed CSI is capable of minimizing the voltage and current ripples even if PWM technique is employed. Hence, the harmonic distortion analysis for both load current and voltage delivered by VSI, CSI and buck-regulator fed CSI are performed in this paper. The analyses are performed with traditional 120° conduction and with multiple carriers based PWM approach. Presently buck-regulator fed CSI has been widely implemented in special motor drives applications. The compared converters are validated with a fixed RL load both in simulation as well as a prototype developed in the laboratory. Results shows that with the use of an inductor with reduced number of turns, the ripples in the output current for the buck-regulator fed CSI is minimized significantly compared to a conventional CSI and hence load side filter can be avoided.

VolvoxDC : A new scalable data center network architecture

Abstract: To contend with increasing requirement of cloud based applications nowadays, it is becoming very essential for the data center networks (DCN) to expand the network capacity very frequently. A good DCN topology must possess several properties for any dimensions of the network such as low diameter, high bisection bandwidth, low cost of deployment etc. Moreover, a DCN topology must also show efficiency in terms of scalability, failure resiliency, routing and construction. In this paper, we propose a novel DCN topology named VolvoxDC which resembles the structure of the similar named multi-cellular Algae Volvox which consists of thousands of cells within it. VolvoxDC is built up with several modules connected via perfect matchings and each module is constructed from an arbitrary diameter 2 graph. VolvoxDC shows excellent topological properties and it outperforms significant topologies like Fattree and Jellyfish in terms of providing a better cost effective design with more capacity.