Showing papers by "North Eastern Regional Institute of Science and Technology published in 2005"

Modeling and analysis of white layer depth in a wire-cut EDM process through response surface methodology

Abstract: A white layer is considered a major flaw on a workpiece surface machined with wire-cut electrical discharge machining (WEDM). In this paper, an attempt has been made to model the white layer depth through response surface methodology (RSM) in a WEDM process comprising a rough cut followed by a trim cut. An experimental plan for rotatable central composite design of second order involving four variables with five levels has been employed to carry out the experimental investigation and subsequently to establish the mathematical model correlating the input process parameters with the response. Pulse on time during rough cutting, pulse on time, wire tool offset, and constant cutting speed during trim cutting are considered the dominant input process parameters whilst the white layer depth is the response. An insignificant “lack of fit” term indicated a curve with a good fit. Also, an extensive analysis of the influences of all the individual input parameters on the response has been carried out and presented in this research study.

Sacred groves of Manipur, Northeast India: biodiversity value, status and strategies for their conservation

Abstract: The people of Manipur, a state in northeast India, follow ancestral worship and animism in the form of deity worship, with the central focus on worship in forest patches. The beliefs and taboos associated with the Sylvan deities (Umanglais) in the forest patches are restricted to any sort of disturbance of flora and fauna. These social boundaries help to conserve the entire organism as a whole, which stand the concept of sacred groves. The pleasing of deities is performed every year by the Meiteis, a dominant community of Manipur, in honour of the deities and to gain their favour. Indigenous cultural and rituals practices of the local people in sacred groves serve as a tool for conserving biodiversity. Sacred groves are distributed over a wide ecosystem and help in conservation of rare and endemic species. Well-preserved sacred groves are store houses of valuable medicinal and other plants having high economic value, and serve as a refuge to threatened species. One hundred and sixty-six sacred groves were inventoried in Manipur valley that comprises Imphal east, Imphal west, Thoubal and Bishnupur districts of the state. Detailed studies were carried out in four selected sacred groves, to know the importance of biodiversity status and vegetation characteristics. A total of 173 plant species representing 145 genera under 70 families were recorded through baseline floristic survey. The species diversity indices were compared among the four studied groves. The vegetation composition and community characteristics were recorded. Ethnobotanical uses of species were examined, which reveal that 96% of the species were used as medicine for the treatment of various ailments. Utilization of herbal medicine by the Meiteis is closely related to the cultural and ritual practices. A few of the medicinal plants which have disappeared from the locality are now confined only to the groves. Socio-cultural aspects were investigated taking into account the attitudes of local people, which indicate social beliefs and taboo are eroding, simultaneously degrading the degree of protection of sacred groves. Therefore, conservation measures of sacred groves need to be formulated considering the factor of degradation and the basic necessities of the local people. Until and unless a viable option is provided to the local people (especially those who habitat nearby the adjoining areas) for sustaining their economic condition, no step for conservation of biodiversity will be successful.

Design of a wideband microstrip antenna and the use of artificial neural networks in parameter calculation

Abstract: This paper deals with the design of a multi-slot hole-coupled microstrip antenna on a substrate of 2 mm thickness that gives multi-frequency (wideband) characteristics. The Method of Moments (MoM)-based IE3D software was used to simulate the results for return loss, VSWR, the Smith chart, and the radiation patterns. A tunnel-based artificial neural network (ANN) was also developed to calculate the radiation patterns of the antenna. The radiation patterns were measured experimentally at 10.5 GHz and 12 GHz. The experimental results were in good agreement with the simulated results from IE3D and those of the artificial neural network. A new method of using a genetic algorithm (GA) in an artificial neural network is also discussed. This new method was used to calculate the resonant frequency of a single-shorting-post microstrip antenna. The resonant frequency calculated using the genetic-algorithm-coupled artificial neural network was compared with the analytical and experimental results. The results obtained were in very good agreement with the experimental results.

Vegetation analysis and tree population structure of tropical wet evergreen forests in and around Namdapha National Park, northeast India

Abstract: Species composition, diversity and tree population structure were studied in three stands of the tropical wet evergreen forest in and around Namdapha National Park, Arunachal Pradesh, India. Three study stands exposed to different intensities of disturbances were identified, viz., undisturbed (2.4 ha) in the core zone of the park, moderately disturbed (2.1 ha) in the periphery of the park and highly disturbed (2.7 ha) outside the park area. In total 200 plant species belonging to 73 families were recorded in three stands. Tree density and basal area showed a declining trend with the increase in disturbance intensity. The densities of tree saplings and seedlings were lower in the disturbed stands than in the undisturbed stand. Species like Altingia excelsa, Olea dioica, Termi- nalia chebula, Mesua ferrea and Shorea assamica in the undisturbed stand and Albizia procera alone in the moderately disturbed stand contributed more than 50% of the total tree density in respective stands. The undisturbed stand contained young tree population. In the highly disturbed stand, the tree density was scarce, but had uncut trees of higher girth class (>210 cm GBH). Low shrub density was recorded in both disturbed stands due to frequent human disturbances; the broken canopy and direct sunlight enhanced the abundance of herbs in these stands. With a species rarity (species having <2 individuals) of ca. 50%, the tropical wet evergreenforests of the Namdapha National Park and its adjacent areas warrant more protection from human intervention and also eco-development to meet the livelihood requirements of the local inhabitants in the peripheral areas of the Namdapha National Park in order to reduce the anthropogenic pressure on the natural resources of the park.

Observations on parturition and allomothering in wild capped langur (Trachypithecus pileatus)

Abstract: A birth during the day by a capped langur (Trachypithecus pileatus Blyth, 1843) was recorded at Pakhui Wildlife Sanctuary, Arunachal Pradesh, India. The birth took 43 min. Allomothering was observed 3 h after the birth. An average of 9% of daily active time was shared by four allomothers (three adults, one subadult) during the first 15 days of the infant's life. Total time allomothering was proportional to the age of the allomothers (241 min for oldest; 214 min for youngest).

Genetic algorithm with artificial neural networks as its fitness function to design rectangular microstrip antenna on thick substrate

Abstract: Over the years, genetic algorithms (GAs) have been applied in many applications. But the lack of a proper fitness function has been a hindrance to its widespread application in many cases. In this paper, a novel techniqueof using artificial neural networks (ANNs) as the fitness function of a genetic algorithm in order to calculate the design parameters of a thick substrate rectangular microstrip antenna is presented. A multilayer feed-forward neural network is used as the fitness function in a binary-coded genetic algorithm. The results obtained using this method are found to be closer to the experimental value, as compared to previous results obtained using the curve-fitting method. To validate this, the results are compared with the experimental values for five fabricated antennas. The results are in very good agreement with the experimental findings.

Experimental investigation of phase transitions exhibited by symmetric liquid crystal dimers

Abstract: As a part of our systematic study of phase transitions in liquid crystal dimers we report here the variation of density across the phase transitions Isotropic – Smectic A and Smectic A – Smectic F exhibited by the Schiff base liquid crystal dimeric compounds of α,ω-bis(4-alkylanilinebenzylidene-4′-oxy)alkane (m.OnO.m) homologous series. The compounds studied are 6.O5O.6 and 6.O6O.6. The compound 6.O5O.6 exhibits only Smectic A phase, whereas the compound 6.O6O.6 exhibits Smectic A and Smectic F phases. The density jumps and peak in thermal expansion coefficient at the transitions confirm the first order nature of the transitions with a smaller density jumps compared to the monomeric liquid crystals. The calculated pressure dependance of the transition temperatures using Clauasius- Clapeyron equation is also reported. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermal decomposition of manganese(II)bis(oxalato)nickelate(II)tetrahydrate

Abstract: A mixed metal oxalate, manganese(II)bis(oxalato)nickelate(II)tetrahydrate, has been synthesized and characterized by elemental analysis, IR spectral and X-ray powder diffraction (XRD) studies. Thermal decomposition studies (TG, DTG and DTA) in air showed that the compound decomposed mainly to Mn2O3, MnO2 and NiO at ca.1000°C, via. the formation of several intermediates. DSC study in nitrogen upto 500°C showed the endothermic decomposition. The tentative mechanism for the thermal decomposition in air is proposed.

Role of social aspects in extent of on-farm tree growing in subsistence agroforestry systems of Western Himalaya

Abstract: Many so-called society-oriented agroforestry programs, mainly in developing countries, fail because they do not take account of the social structure in their design. This study provides empirical evidence of the impact of social structure on the extent of on-farm tree growing. The study has been carried out in Mandi district of Himachal Pradesh, in Indian Western Himalaya. Analysis of survey data reveals significant relationships between extent of on-farm tree growing and caste, education of the head of household, family literacy, primary occupation, government employment, mobility of the household head, importance of tree growing for future generations, and holy tree worship practices. Households with concrete houses had more trees than households with mixed, mud and wooden houses. The study implies a need to consider social factors to encourage the level of on-farm tree growing and to design socially acceptable agroforestry programs. The study also emphasises the need for a holistic approach to agroforestry development by integrating other continuing rural development programs with that of agroforestry to increase the level of on-farm tree growing.

Surface energy effect on boiling heat transfer

Abstract: Boiling is a complex phenomenon and depends upon many factors like liquid properties, liquid pressure and temperature, temperature of the heating surface, orientation of the heating surface, surface chemistry, etc. Study of the effect of surface energy, one such factor, on boiling heat transfer is carried out and presented here. Data for various fluids viz. water, different types of alcohols and for various surfaces has been collected from the open literature and analysed with regard of effect of surface energy. The results of the investigations along with the recommendations have been presented in this paper. The investigations have shown that the increase in surface energy has resulted in increase in the heat transfer coefficient for distilled water, while the increase in surface energy has resulted in decrease in the heat transfer coefficient for alcohols. There is scarcity of relevant data available for further investigation and in this regard, need for benchmark data has been raised. Also need for establishment of a standard for comparison and analysis of different experimental results has been put forth.

Effect of drum-grain-operating parameters on the flow rate through the orifices on the rotating drum

Abstract: The flow of granular material in a rotating cylinder is common in many industrial applications. In agriculture, a paddy sowing equipment called drum seeder has the orifices on the edges of a rotating cylindrical drum, through which the paddy grains fall out during the operation. The flow rate depends on various drum, grain and operating parameters. An investigation was undertaken to study the effect of the various drum, grain and operating parameters on the flow rate and develop certain empirical equations for the flow rate. The study revealed that the spacing of orifice, diameter of orifice, percent fill of drum and speed of rotation of the drum significantly affect the flow rate. However, the flow rate is independent of the percent fill of grains in the drum up to the orifice diameter of 1.28 times the equivalent grain diameter when the spacing of orifices is in the range of 3–4 times the orifice diameter and speed of operation varied from 18.83 to 47.17 m/min.

Determination of Optimum Particle Size for Economical Hydrotransport

Abstract: In the present work the generalized mathematical model (SK model) developed by Shrivastava and Kar [1, 2] has been utilized to determine the optimum size of the solid particles (sand, coal, pvc- granules, and lead shot), which offers the minimum frictional resistance to flow and results into the minimum head loss when transported through horizontal pipes under the conditions identical to those achieved by the investigators [3- 6] in their experiments. On the basis of the present investigation it has been observed that for the transport of solid through horizontal pipe at constant throughput the head loss does not depend directly on the size of the particles rather it depends on the values of the critical velocity (fluid velocity at which the head loss is minimum in the characteristic curve) calculated for solids of different sizes. Whereas for the transport of solid particles at constant volumetric concentration the head loss depends directly on the size of the particle and it is minimum for the largest size of the particle. Thus, it is possible to determine the optimum size of the particles for economical hydrotransport through horizontal pipe at constant throughput from the energy consumption point of view by utilizing the expressions of SK model.Copyright © 2005 by ASME

Application of a genetic algorithm in an artificial neural network to calculate the resonant frequency of a tunable single-shorting-post rectangular-patch antenna: Research Articles

Abstract: In this article, an efficient application of a genetic algorithm (GA) in an artificial neural network (ANN) to calculate the resonant frequency of a coaxially-fed tunable rectangular microstrip-patch antenna is presented. For a normal feed-forward back-propagation algorithm, with a compromise between time and accuracy, it is difficult to train the network to achieve an acceptable error tolerance. The selection of suitable parameters of ANNs in a feed-forward network leads to a high number of man-hours necessary to train a network efficiently. However, in the present method, the GA is used to reduce the man-hours while training a neural network using the feed forward-back-propagation algorithm. It is seen that the training time has also been reduced to a great extent while giving high accuracy. The results are in very good agreement with the experimental results. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.