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.

Natural Convection in a Nano-Fluid Filled Square Enclosure

Abstract: The present study relates to numerical investigation of natural convection heat transfer in a nanofluid filled square enclosure. One side of the enclosure is maintained at high temperature and the other side at a low temperature; while the top and bottom sides are adiabatic. The commercial CFD software ANSYS-FLUENT© was used to solve this numerical problem with the governing differential equations discretized by a control volume approach. nanofluids of Cu-water, Al2O3-water and TiO2-water have been simulated for a range of Rayleigh numbers and volume fractions. The results were obtained in the form of streamlines and isotherms. Interpretations of the results are done based on heat transfer rates, volume fraction, Rayleigh number and Nusselt number. It is to be noted that addition of nanoparticles enhances the heat transfer rate. It is also observed that the Nusselt number is highly affected by volume fraction and Rayleigh number.

Distributed Generator Based DVR Application to a LV Distribution Grid

Abstract: In this work, small distributed power generators of renewable energy sources are connected to the distribution grid with nonlinear/dynamic loads. The effect on the power quality of the proposed system is analyzed via dynamic voltage restorer (DVR). The distributed generators (DGs) are integrated and fed to distribution grid through de link of DVR interfacing inverter which is a series inverter linking the DGs to the distribution grid. The DGs as energy storage device regulates the dc link voltage of DVR. The distributed generator consisting of a photovoltaic system (PVS), a wind energy conversion system (WECS) and a micro hydro system (MHS) is proposed. The motivation is on improvement of power quality (PQ) in terms of harmonics and voltage sag. An instantaneous symmetrical component theory (ISCT) for fundamental voltage extraction and hysteresis current control technique for PWM generation is implemented. The complete system is modeled using MATLAB/Simulink SimPower system block set. The proposed system is subjected to nonlinear and dynamic loads and the simulated results are presented. The total harmonic distortion (THD) is shown to analyze the harmonic content in load voltage. The performances of the DVR are found to be tolerant under various load perturbations.

Bulk-driven feed-forward compensated sub-threshold low-voltage OTA to drive high capacitive load

Abstract: This paper presents a three-stage low-voltage bulk-driven sub-threshold class AB current mirror load operational transconductance amplifier (OTA) which utilizes FVF based input core and feed-forward compensation techniques for its low-voltage operation to drive high capacitive load. This three-stage OTA provides a gain of 94.4 dB, gain bandwidth (GBW) of 14.2 kHz and phase margin (PM) of 64 degree with load capacitor (Cl) and two small compensation capacitors (Cc1 and Cc2) of 100 pF, 2 pF and 0.02 pF, respectively. This OTA has ensured the total harmonic distortion (THD) of −49 dB for 0.5 Vpp input signal of 200 Hz frequency, while driving 100 pF load in its unity gain configuration. Biased with a single supply of 0.5 V it has consumed quiescent power of 104 nW. It offered high common mode rejection ratio (cMRR) and power supply rejection ratio (PSRR) of 138 dB and 81 dB, respectively at 1 Hz. Simulations results are performed using standard n-tub 180 nm CMOS process with UMc technology file in cadence spectre environment.

Identification of Critical Pipes for Water Distribution Network Rehabilitation

Abstract: The water distribution network needs to be rehabilitated when the network is unable to perform the desired function. In this study, a methodology is developed to identify the critical pipes in the water distribution network for its rehabilitation by using four network reliability metrics: supply shortage, pressure decline, energy loss per unit length, and the hydraulic uniformity index. These metrics consider different aspects of reliability of the water distribution network using pressure-dependent analysis to calculate the overall criticality of the pipes. In contrast to the conventional reliability index, the present study uses both the normal and abnormal conditions at nodes (fire demand) and pipe (pipe failure) and thus, provides more balance reliability metrics for the network. The literature shows that the node and pipe level metrics have been used separately, whereas in this study both the node and pipe level metrics are combined to develop the present methodology. The methodology is applied to four different water distribution networks, including one typical realistic water distribution network, the data for which is adopted from literature. The results show that the methodology can identify the critical pipes successfully to prioritize the water distribution network rehabilitation and found to be simple in implementation for practicing professionals. The results further show that the critical pipes are found to be located from the source on the paths that do not have a loop or around the nodes of higher demand. The study might also be useful for the extension plan of a water distribution network along with strengthening the deficient nodes/ pipes of the network.