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.

Scalable discrete Tchebichef Transform for image/video compression

Abstract: The objective of the paper is to study the performance comparison between scalable Discrete Tchebichef Transform (DTT) and Discrete Cosine Transform (DCT) on an image/ video frame. This proposed work uses the property of orthogonality of Tchebichef transform. Different block sizes (i.e. 4×4, 8×8, 16×16, and 32×32) of DCT and DTT are performed on different class of images. From the results, it was observed that the Peak Signal to Noise Ratio (PSNR) in case of DTT is better when compared to DCT. The computational complexity of DCT and DTT remains same because only the transform coefficients are different in both cases. Thus DTT can be preferable compared to DCT for image/video compression.

An Experimental Investigation to Check the Overall Performance of a Packed Bed Solar Air Heater

Abstract: An experimental investigation of thermohydraulic performance characteristics of a packed bed solar air heater is done in the present work. The packed bed is generally used to enhance the heat transfer area, increase the turbulence in the flow and for the storage of thermal energy. The experimental investigation has been carried out on a low porosity packed bed solar air heater. The investigation covers a particular range of design and operating parameters. Design parameters take account of the equivalent diameter of packing material (1.55 mm), packing density (250 g per 0.075 m3) and colour of the packed bed material (Black) while the operating parameters take account of the mass flow rate ranging from 0.01 to 0.04 kg/s. It is observed that the efficiency of the air heater increases with increase in mass flow rate. It is also found that the impact on the overall efficiency due to frictional loss is much less in a low porosity packed bed solar air heater.

Simultaneous Solving of Batched Linear Programs on a GPU

Abstract: Linear Programs (LPs) appear in a large number of applications. Offloading the LP solving tasks to a GPU is viable to accelerate an application's performance. Existing work on offloading and solving an LP on a GPU shows that performance can be accelerated only for large LPs (typically 500 constraints, 500 variables and above). This paper is motivated from applications having to solve small LPs but many of them. Existing techniques fail to accelerate such applications using GPU. We propose a batched LP solver in CUDA to accelerate such applications and demonstrate its utility in a use case - state-space exploration of models of control systems design. A performance comparison of The batched LP solver against sequential solving in CPU using the open source solver GLPK (GNU Linear Programming Kit) and the CPLEX solver from IBM is also shown. The evaluation on selected LP benchmarks from the Netlib repository displays a maximum speed-up of 95x and 5x with respect to CPLEX and GLPK solver respectively, for a batch of 1e5 LPs.

Analysis of Global Bifurcation and Chaotic Oscillation in Distributed Generation Integrated Novel Renewable Energy System

Abstract: In this paper, a distributed generation (DG) integrated novel renewable energy system is proposed and analysis of bifurcation, chaotic behavior is observed. The integration of DG is the main property of renewable energy system, so in this model wind turbine generator (WTG) is integrated as a DG. Furthermore, dynamical load and Flexible AC Transmission System (FACTS) devices are also integrated. Renewable energy system is very complex, nonlinear dynamical system and it may exhibit chaos phenomenon in case of small, large disturbances or system parameter variations. The study of bifurcation and chaos behavior is essential in the proposed renewable energy system because it may lead to very serious results like voltage collapse, angle instability sometime blackout. The observation of bifurcation and chaotic oscillations are analyzed for wide range of parameter variations with the help of Lyapunov exponent, Lyapunov spectrum and bifurcation diagram. Simulation are done in MATLAB environment and simulation results reveals that the objective is achieved successfully.

A Study of Wire Electrical Discharge Machining of Carbon Fibre Reinforced Plastic

Abstract: The need for nonconventional machining of carbon fibre reinforced plastics (CFRPs) has emerged due to several problems encountered during their conventional machining. Wire electrical discharge machining (WEDM) is a potential nonconventional machining process having the ability to produce delamination and damage-free features in CFRP laminate. But machining of CFRPs by means of WEDM is a challenging task due to their low electrical conductivity characteristic. The present work focuses on the feasibility study of machining of CFRP laminate by WEDM process. Sandwich assisting electrode method was applied to improve the machining performance of the chosen material. The influence of three input factors, namely, (i) pulse on time, (ii) pulse off time, and (iii) current on machining time has been investigated. The experiments were performed according to full factorial design by taking three levels of each input factor. It was found from the experimental results that the machining time increases marginally with an increase in the pulse on time at a lower level of current (current level of 2). However, the machining time is almost constant for a higher level of current (current level of 4 and 6). The results also showed that the machining time increases with pulse off time and decreases with the current.