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.

Improved dynamic model of induction motor including the effects of saturation

Abstract: This paper presents an improved dynamic model with incorporating the saturation effects for an induction motor (IM). The improved model is simulated with MAT-LAB/SIMULINK software for transient response in terms of electromagnetic torque, rotor speed and stator current at no-load and on-load. The obtained simulated results provide a clear evidence that the conventional unsaturated model fails to predict the actual dynamic behavior of the IM. The observations are validated with the experimental results which will show that the obtained model can be used to study the dynamic behavior of IM.

A QoS-aware multipath routing protocol for WiFi-based long distance mesh networks

Abstract: Routing plays a crucial role in provisioning Quality of Service (QoS) over WiFi-based Long Distance (WiLD) mesh networks. Traditional routing protocols normally maintain a single optimal path between each pair of source and destination nodes. In gateway-based mesh networks, the optimal paths between gateway and other nodes often overlap and hence degrades the overall network performance significantly. Multipath routing protocols are widely used in Wireless Mess Networks (WMN) for providing QoS to various network applications. Smooth routing of real time traffic with varying QoS requirements is a challenging task. In this paper, we propose a QoS-aware hybrid multipath routing protocol which can discover multiple maximally disjoint paths between a gateway and any other node. The gateway node selects n-best paths for the source node. Before starting a given real time flow, a path selection scheme chooses the appropriate path or set of paths amongst the available discovered paths. To evenly distribute the traffic among the paths chosen, an admission control mechanism has been proposed. In case of significant change in the quality of any discovered paths, a path maintenance process induces the source node to trigger a route update process. The proposed protocol enhances the performance of real time traffic significantly. The simulation results show that the proposed protocol achieves significant improvement in different QoS parameters. With the increase in number of disjoint paths from source to destination, a substantial improvement in throughput and delay is observed.

Buckling of fixed-ended concrete-filled steel columns under axial compression

Abstract: In recent years, due to a relatively high price increase of nickel alloys, there is an increase in demand for lean duplex stainless steel (LDSS) with a low nickel content of ~1.5%, such as grade EN 1.4162. LDSS offers roughly twice the strength compared to austenitic stainless steels and has great potential for expanding future structural possibilities, enabling a reduction in the section sizes leading to lighter structures. This paper reports the buckling behavior of fixed-ended concrete-filled LDSS tubular (CFDSST) columns with L-, T-, and +-shape (Non-Rectangular Sections or NRSs) sections and a representative square section with varying lengths through Finite Element (FE) analysis. The purpose is to compare and assess the strength and deformation characteristics as well as the failure modes of such columns. It is seen that concrete-filled tubular columns with NRSs offered a better performance for all lengths considered, especially the T-shaped and +-shaped sections, in terms of strength. The influence of the cross-sectional shapes on the e u becomes less significant with increasing λ, but becomes increasingly significant with decreasing λ. The design standards show over conservative results for square and L-shape sections and conservative for T-shape and +-shape sections.

Design and Control of An Asymmetrical Cascaded Compact Module Multilevel Inverter for PV System

Abstract: High-penetration of renewable sources and wide application of electric drives has increased the research effort in power converter technology. Multilevel inverters (MLIs) are the well-known power converters that are suitable alternative to the traditional three-level inverters for power quality improvement in different applications. Nevertheless need of more number of switches and dc sources are the shortcoming in conventional MLIs. To address this issue, this paper presents an asymmetric compact module MLI using fewer switch count and less number of dc sources. In addition, the proposed MLI has low standing voltage and less loss as compared to few state-of-art MLI topologies. The developed module can be cascaded further to increase the number of levels. Using $\boldsymbol{n}$ such modules, $16\boldsymbol{n}+1$ level output can be obtained. Selective harmonic elimination (SHE) PWM technique is analyzed to verify the operation of a 17-level MLI. MATLAB/SIMULINK platform is used for extensive simulation under different conditions such as at different modulation indices, change in frequency and load dynamic conditions. The theoretical and simulated findings are further validated experimentally on a prototype developed in the laboratory.