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.

Study on land-use and land-cover change dynamics in Eastern Arunachal Pradesh, N.E. India using remote sensing and GIS

Abstract: The current study describes the land use and land cover dynamics in Eastern Arunachal Pradesh from 1985 to 2005 using remote sensing and Geographical Information System (GIS). Landsat-MSS, IRS-LISS-I and LISS-III data for the period 1985, 1995 and 2005 were used to prepare the land use/land cover (LULC) map at 1:250K for different periods. Post-classification change detection technique for quantifying the changes for twelve major land use and land cover types was analyzed. The study signifies that the region experiences expansion in crop land and built-up area and decline in forest area. Crop land and built-up area has increased by 665.41 km2 and 16.72 km2, respectively, from 1985 to 2005. On the other hand, forest area has declined by 699.37 km2 during the period. The study showed that topography and increasing population play an important role in shaping the LULC pattern. The study further revealed the importance of satellite remote sensing and GIS as an effective approach for analyzing the direction, rate and spatial pattern of land use dynamics. It is believed that this type of study will help to contribute towards sustainable land-use planning and management in this part of the North East India in the near future.

Assessment of woody species diversity and composition along a disturbance gradient in Behali Reserve Forest of Biswanath district, Assam, India

Abstract: The present study was carried out in Behali Reserve Forest, a semi-evergreen forest of Assam, India to record and analyze the woody species diversity and community characteristics using random sampling. Altogether, 35 quadrats (20 m × 20 m) were randomly established and studied from August 2018 to April 2019 spreading across nine study sites. A total of 128 (118 identified and 10 unidentified) woody species from 83 genera and 43 families were found in the sampled area of 1.4 ha. Lauraceae with 19 species was the richest family by species followed by Euphorbiaceae and Phyllanthaceae (eight species each). Altogether, 787 individuals were recorded from the sampled plots and the stand density ranged between 250 individuals × ha-1 to 725 individuals × ha-1 with mean stand density of 543 individuals × ha-1. Species-wise density analysis revealed that Magnolia hodgsonii (96.43 individuals × ha-1) has the maximum tree density. Plot wise analysis showed that Dikal (58.32 m2 × ha-1) recorded the maximum basal area as well as the equitability index of 0.95. In Serelia, we recorded the highest Simpson index (0.92), Shannon H index (2.76), Brillouin index (2.11), Menhinick (3.49), Margalef (5.29) and Fisher alpha index (26.59). In Radhasu, we recorded maximum evenness (0.90), dominance (0.58) and Berger-Parker index (0.65). The maximal values of Chao index (38.53) was recorded in Hatimara. Our study also revealed that diversity was maximal for the community under medium level of disturbance in the reserve, while communities under the lowest and highest disturbance pressure had minimal diversity. The Behali Reserve Forest exhibited a great species richness (118 species), mean basal area (44.42 m2 × ha-1) and stand density (in total, 788 individuals per study area of 1.4 ha) compared to the other forests of the northeastern region of India.

Estimation of infiltration rate from readily available soil properties (RASPs) in fallow cultivated land

Abstract: The information about water transmission rate into the ground is vital concerning the productivity of water system and seepage, advancing the accessibility of water for the plants, enhancing the yield of harvests, limiting degradation of soil and wastage of the water. Infiltration rate can successfully be measured using double ring infiltrometer. However, measurement of infiltration in the field is labour and time consuming and difficult especially in mountainous sites. As an alternative, RASP-based infiltration models can be developed. The study was carried out in the field near the NERIST campus (Nirjuli Complex), Arunachal Pradesh, India. Twenty sites were identified at the grid of 10 m interval, and the field measurement of infiltration was performed. The soil was analysed for properties, namely, soil texture, bulk density (BD), particle density (PD), moisture content (MC), and organic carbon content (OC) for each site. The basic infiltration varied from 1 to 4.84 cm/h. The Scatter plot between RASPs and infiltration rate revealed that there is a positive correlation with OC, PD, and sand, and a negative correlation with BD, MC, silt, and clay. The partial least square regression (PLSR) analysis was carried out to develop predictive models for five different groups of inputs of soil properties. The influential variable projection (VIPs) analysis revealed sand as a highly influential factor, while silt as a reluctant predictor of infiltration characteristics of the study site. It was found that to predict the soil infiltration rate based on RASPs with seven independent variables (Eq. 13) with coefficient of determination (R2) 0.92, root mean square error (RMSE) 0.378 cm/h, mean absolute error (MAE) 0.143 cm/h, and standard error (SD) 0.398 cm/h is strongly recommended for the prediction of infiltration characteristics.

An effective emitter-source localisation-based PUEA detection mechanism in cognitive radio networks

Abstract: Cognitive Radios (CRs) aim at improving the efficiency of spectrum utilisation by making use of the spectrum holes in the licensed radio spectrum which otherwise would remain unused leading to underutilisation of spectrum resources. The idea is to utilise the unused licensed radio frequencies in the absence of the licensed users called Primary Users (PUs) and leave the same when the licensed users return. However, there are several security threats holding back the successful realisation of CR networks. Primary User Emulation Attack (PUEA) is one such major threat in CR networks, in which the attackers disguise themselves as PUs by mimicking the signal characteristics of the PUs, in order to make the legitimate Secondary Users (SUs) erroneously identify the attackers as PUs and hence, vacate the spectrum. It is obvious that such attacks will cause many SUs to lose access to the network services leading to overall performance degradation in the entire network. In this paper, we propose a Hyperbolic-based Transmitter Localisation technique using TDOA to defend against PUEA. The results show successful detection of the PUEA attackers along with accurate positions of the attackers.

Insulation and Cooling Performance of Transformer Oil Based Nanofluid

Abstract: The transformer oil in electrical equipment is mainly used for insulation and cooling purpose of the equipment. This paper presents the experimental results of insulation and cooling performance of transformer oil (mineral oil and MIDEL-7131) based nanofluids. The nanofluids were prepared using SiO 2 nanoparticle with a percentage concentration (W/V ratio) of 0.1, 0.3, 0.5 and 0.7. The results were compared with the base oil and it was found that with the increase in concentration of nanoparticle in the base oil, thermal conductivity of the nanofluid increases by 5% for a percentage concentration of 0.7% in mineral oil and 10% in MIDEL-7131. The impulse dielectric strength of the nanofluid sample also increases up to 25% at a percentage concentration of 0.5% in mineral oil based nanofluid and 18% in MIDEL-7131 oil based nanofluid as compared with their base oils. But unfortunately the AC breakdown voltage of the nanofluids decreased, this decrease in AC breakdown voltage may be due to the increase in moisture content.