North Eastern Regional Institute of Science and Technology

About: North Eastern Regional Institute of Science and Technology is a education organization based out in Itanagar, India. It is known for research contribution in the topics: Population & Raman spectroscopy. The organization has 813 authors who have published 1429 publications receiving 16122 citations.

Reliability and Security Analysis of VoIP Communication Systems

Abstract: Voice over Internet Protocols (VoIP) is a technology for sending voice in the form of digital packets over IP-based networks. Organisations are diverting from traditional communication media to VoIP system because of cost-saving factors and it is easy to install. It is going to be the main component for next-generation networks. Many organisations provide communication services but unable to fulfil the requirements of reliable and secure services to its customers. In this paper, we discuss reliability and security problems in VoIP system with possible measures. We analyse the security threats for confidentiality, integrity and availability. It is observed that gaining a higher level of reliability and security is still a major challenge in VoIP communication systems.

Reducing Frequency Deviation of Two Area System Using Full State Feedback Controller Design

Abstract: More than one generating power stations are interconnected, to meet the increasing energy demand and to maintain the energy equation. It is desired to have minimum deviation frequency in the system with the variation in dynamic load. There are various control techniques to achieve the desired dynamic system response. This paper models the two similar and dissimilar units. The generating station models used for analysis are thermal non-reheat, reheat and hydro turbine. The frequency deviation response for the unit is obtained with I-controller and compared with its full state feedback controller. The whole system is simulated in MATLAB Simulink.

Determination of surface drainage coefficient - a case study of Doimukh (Arunachal Pradesh), India

Abstract: In this study, 1 day to 7 consecutive days annual maximum rainfall was predicted at various return periods using probability distribution functions for Doimukh (Arunachal Pradesh), India. Basic infiltration (Ib) rate value was estimated 10 mm hr -1 for the agricultural field having sandy soil. The drainage coefficient was estimated for 5, 10, 20 and 25 years R.I. by subtracting basic infiltration rate from estimated consecutive day rainfall. For the study area, the maximum value of drainage coefficient at 25 years recurrence interval varied from 41.37 mm day -1 to 304.23 mm day -1 for 2 to 7days consecutive rainfall. The minimum value of drainage coefficient at 5 years interval varied from 0 to 212.30 mm day -1 for 2 to7days consecutive rainfall. Study concluded that sandy soil of Doimukh (Arunachal Pradesh) having basic infiltration rate 10 mm hr -1 had to be provided with agricultural drainage for its major crops grown in the area.

FE-Based Heat Transfer Analysis of Laser Additive Manufacturing on Ti–6Al–4V Alloy

Abstract: A thorough understanding of laser-based additive manufacturing process and effect of various process variables such as scanning velocity and laser beam power on melt-pool dimensions and temperature variation is a promising task in design and manufacture of an able product. The present work is focused on comprehending the thermal and melt-pool behavior of a high layer thickness five-layer laser additive manufacturing of Ti–6Al–4V alloy quantitatively. A three-dimensional (3D) nonlinear transient thermal model is developed based on a finite element procedure to simulate single- and multi-layer of Ti–6Al–4V alloy and to estimate melt-pool dimensions and thermal cycles. In this work, temperature-dependent material properties and Gaussian distributed ‘disk’ heat source model are implemented along with actual process boundary and initial conditions. Also, the influence of laser beam power and laser scanning velocity was examined with respect to melt-pool characteristics and thermal cycles. The laser scanning velocity ranges from 200 to 500 mm s−1 and laser beam power from 100 to 400 W are examined. It is observed that the temperature rises for successive layers as the laser power supply continues on consecutive layers. Also, it is obvious that with the rise in temperature, melt-pool dimensions also increase. Furthermore, the melt-pool dimensions increase as the number of deposited layers increases. Time–temperature history and melt-pool evolution in different layers with respect to laser beam power and laser scanning velocity are presented. To verify the effectiveness of the developed model, simulated results are compared with experimentally measured melt-pool profiles and dimensions. A fair agreement between experimental results and computed values is achieved.

A Novel Design and Modeling of Beam Bridge Structure Piezoelectric Pressure Sensor Base on ZnO

Abstract: The main objective of this study is to design a ZnO base beam bridge MEMS piezoelectric pressure sensor. A theoretical mathematical modeling of the design is derived for the structure. Factor effecting the output or efficiency is studied base on mechanical and electrostatics step by steps. A simulation is conducted on Comsol Multiphysics Simulator for the design for validating the theoretical modeling and a comparative study are made between the analytical and simulated result. This study will help to find the optimum design structure for piezoelectric pressure sensor base on bridge beam structure.