Showing papers by "North Eastern Regional Institute of Science and Technology published in 2002"

A novel method of using artificial neural networks to calculate input impedance of circular microstrip antenna

Abstract: A new method of using artificial neural networks(ANNS) for calculation of input impedance of rectangular microstrip patch antennas has been adopted in this paper. The results obtained using ANNs are compared with the experimental findings, theoretical values. The ANNs results are more in agreement with experimental findings.

MnO2-polypyrrole conducting polymer composite electrodes for electrochemical redox supercapacitors

Abstract: Redox supercapacitors using electrochemically synthesised MnO2-polypyrrole composite electrodes have been fabricated with different electrolytes, namely polymer electrolyte film (polyvinyl alcohol, PVA-H3PO4 aqueous blend), aprotic liquid electrolyte (LiClO4-propylene carbonate, PC) and polymeric gel electrolyte [poly methyl methacrylate, (PMMA)-Ethylene carbonate (EC)-Propylene carbonate (PC)-NaClO4]. The capacitors have been characterised using galvanostatic charge-discharge methods. The cell with aqueous PVA-H3PO4 shows non-capacitive behaviour owing to some reversible chemical reaction of MnO2 with water while the MnO2-polypyrrole composite is found to be a suitable electrode material for redox supercapacitors with aprotic (non-aqueous) electrolytes. The solid state supercapacitor based on MnO2-polypyrrole composite electrodes with gel electrolyte gives stable values of capacitance of 10.0–18.0 mF cm−2 for different discharge current densities.

Input impedance of rectangular microstrip patch antenna using artificial neural networks

Abstract: A new method of using artificial neural networks (ANNs) for the calculation of the input impedance of rectangular microstrip patch antennas has been adopted in this paper. The results obtained using ANNs are compared with the experimental findings, theoretical values, and with the simulation results obtained using an IE3D package. The ANNs result are more in agreement with experimental findings. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 381–383, 2002.

Radiation resistance of coax‐fed rectangular microstrip patch antenna with the use of artificial neural networks

Abstract: A novel method of using artificial neural networks (ANNS) for the calculation of the radiation resistance of a coax-fed rectangular microstrip antenna is presented in this Letter. The network is trained with the results of three different antennas and tested for the fourth antenna. The tested results are in very good agreement. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 51–53, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10370

Flow distribution parameters in relation to flow resistance in an upflow anaerobic sludge blanket reactor system

Abstract: The use of flow resistance in the distribution of flows is well known in traditional hydraulics. To evenly distributed flows, flow resistance forms the basis of flow distribution in pipes connected in parallel. Flow distribution in different zones of upflow anaerobic sludge blanket (UASB) reactors is well documented in existing literature, and so far modeling of flow distribution parameters, i.e., the fraction of inflow entering into the bed, the fraction of flow bypassing over the bed and entering into the blanket, and the fraction of inflow to the bed entering into the blanket, has remained empirical in nature. The role of flow resistance in the distribution of flows in UASB reactor systems is still unexplained. In this study, some of the available data on flow distribution parameters are analyzed to assess if there is any correlation between these parameters and flow resistance. It is found that with an increase in flow resistance in the UASB reactor system, the magnitude of short-circuiting flows at the reactor bed increases. Also, the flow distribution at the blanket and settler levels of UASB reactor systems is related to parameters influencing flow resistance. Some of the functional forms derived in this study are expected to form the basis for representing flow distribution in the simulation studies of UASB reactor performance.

Phase transition studies in mesogenic dimers

Abstract: Schiff base liquid crystal dimers, both symmetric and non-symmetric, in which two anisotropic groups are linked by a flexible spacer, exhibit a rich variety of smectic mesomorphism. The interest in this class of mesogens stems not only from their ability to act as model compounds for semi-flexible main-chain liquid crystal polymers but also from their quite different properties compared to conventional low molar mass liquid crystals (monomers). We report here the phase transition studies on two examples of these schiff base liquid crystal dimers using the Differential Scanning Calorimetry and density measurements as a function of temperature. The symmetric liquid crystal dimer, α,ω-bis (4-n-dodecylaniline benzylidene-4'-oxy)decane (10.O12O.10) exhibits a very rare Isotropic to G transition. Where as, the non-symmetric dimer, α-(4-cyano biphenyl-4'-yloxy)-ω-(4-n-decylanilinebenzylidene-4'-oxy)decane (CB.O10O.10) exhibits a rare nematic to intercalated smectic A phase transition. The transitions studied, isotropic to nematic and isotropic to G exhibit a large density jump at the transition confirming their first order nature. Nematic to intercalated smectic A transition is found to be a second order transition whose behavior is similar to nematic to smectic A transition. Calculated values of pressure dependence of transition temperature and thermal expansion coefficient are also reported.

Influence of pollution on the performance of metal oxide surge arresters

Abstract: Surge arresters are used as key equipment to protect costly substation and transmission line equipment against atmospheric as well as switching over voltages. Reliability of surge arresters has been the subject matter of many studies. Elimination of series gaps in metal oxide surge arresters (MOSA) avoids variation in protective levels caused by erratic gap spark over. MOSA has extremely stable protective characteristics and is very fast acting device, offers lower protective levels at high rates of discharge current. But, in the presence of contamination and moisture, there is the possibility of flow of leakage currents internally and externally both of which may distort the uniformity of voltage distribution across the MOSA. Nonuniform voltage distribution may cause voltage stress and lead to stress degradation. Internal leakage current may also raise temperature around metal oxide discs and lead to thermal run-away. Stress degradation and initiation of thermal run-away process may affect the stability and energy absorption capability of the MOSA. In this paper, an effort has been made to suggest an algorithm with the help of which voltage and current distribution, inside and outside the polluted MOSA could be studied and flashover conditions be achieved. Dynamic surface resistance change during formation and quenching of dry bands due to leakage current has been considered.

Variability in physico-chemical parameters of Pachin river (Itanagar).

Abstract: The concentration of water quality parameters in river and heavy metals in the bed sediment were measured for Pachin River for the three major flow periods. The pH, temperature (degree C), conducity (microS cm-1), DO, COD, NH3, PO4, total hardeness and alkalinity (mg/L) were found in the range of 12 to 22, 6.90 to 7.69, 25 to 211, 5.0 to 12.5, 10-115, 1.2 to 12.0, 0.05 to 0.62, 14 to 45, and 12 to 35, respectively. The heavy metals as Zn and Se showed an enrichment of 1 to 25, and 5 to 120, with concentration (microgram/g) range of 8 to 385 and 0.5 to 6.0, for the respective metal, in the labile fraction of the bed sediment. The variability in the physico-chemical parameters for different flow periods may be assigned to dilution of river water by direct runoff, human activities and organic load. The correlation study of physico-chemical parameters shows that their source of entering the river system is the same whether it may be a natural or anthropogenic or both.

Tunnel‐based artificial neural network technique to calculate the resonant frequency of a thick‐substrate microstrip antenna

Abstract: The mathematical formulation of empirically developed formulas for the calculation of the resonant frequency of a thick-substrate (h ≥ 0.08151λ0) microstrip antenna has been analyzed. With the use of tunnel-based artificial neural networks (ANNs), the resonant frequency of antennas with h satisfying the thick-substrate condition are calculated and compared with the existing experimental results and also with the simulation results obtained with the use of an IE3D software package. The artificial neural network results are in very good agreement with the experimental results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 460–462, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10495

N-Methylethylxanthocarbamate as an Analytical Reagent: Differential Pulse Polarographic Determination of Cadmium in Standard Alloys, Biological and Environmental Samples after Adsorption of its Complex on Microcrystalline Naphthalene

Abstract: N-methylethylxanthocarbamate has been used as an analytical reagent for the determination of trace amounts of cadmium in standard alloys, biological, and environmental samples. The reagent has been found to form a water insoluble complex with cadmium. It is quantitatively adsorbed over microcrystalline naphthalene in the pH range 2.5 to 12.0. The metal complex is desorbed with HCl and cadmium determined with a differential pulse polarograph. The detection limit is 0.05 ppm (signal-to-noise ratio = 2) and the linearity is maintained in the concentration range 0.2–25 μg/ml, with correlation coefficient of 0.9995 and a relative standard deviation of ±0.81%. Characterization of the electroactive process includes an examination of the degree of reversibility. Various parameters, such as the effect of pH, reagent concentration, amount of naphthalene, volume of aqueous phase, and the interference of a large number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for its determination in various complex materials.

Pneumotransport of Grains Through a Pipeline

Abstract: Determination of pressure drop correlation using experimental techniques has been a central topic of research in the area of pneumotransport. However, the objective of the present investigation is to apply the mathematical model (SK model) developed by the author [1,2] along with other correlations [3–5] to estimate pressure drops for conveying varieties of grains through horizontal pipe and compare the values with the experimental results of Siegel [6]. The SK model has also been utilized to calculate pressure drops for conveying mustard seeds pneumatically through horizontal, inclined and vertical pipes and compare the values with the experimental results of Rose and Barnacle [7]. It is evident from various comparisons shown in this paper that the SK model predicts the values of pressure drop accurately as compared to the experimental results in all the cases of grains transport through horizontal, inclined, and vertical pipes, whereas, other correlations do not predict accurate results consistently in all cases.Copyright © 2002 by ASME

Appropriate mechanization for sustainable agriculture in North East India

Abstract: A case study was carried out during 1994–99 in north east India and it was found that introduction of appropriate mechanization to various types of land could provide sustainability to agriculture. The small tractor (20 hp), power tillers and bullocks were found suitable for foot hill land, whereas medium size tractor (35 hp) for plain valley and river bank. He-buffaloes were found suitable for waterlogged areas and swamps. The human labour was found to be an appropriate source of farm power for hill slope. The large size tractor (45 hp) could do subsoiling and uprooting of old tea bushes and medium size tractor (35 hp) performed all transport operations on tea gardens.

A new class of scale free solutions to linear ordinary differential equations and the universality of the Golden Mean ${\frac{\sqrt{5}-1}{2}}$}

Abstract: A new class of finitely differentiable scale free solutions to the simplest class of ordinary differential equations is presented. Consequently, the real number set gets replaced by an extended physical set, each element of which is endowed with an equivalence class of infinitesimally separated neighbours in the form of random fluctuations. We show how a sense of time and evolution is intrinsically defined by the infinite continued fraction of the golden mean irrational number ${\frac{\sqrt{5}-1}{2}}$, which plays a key role in this extended SL(2,R) formalism of Calculus. Time may thereby undergo random inversions generating well defined random scales, thus allowing a dynamical system to evolve self similarly over the set of multiple scales. The late time stochastic fluctuations of a dynamical system enjoys the generic $1/f$ spectrum. A universal form of the related probability density is also derived. We prove that the golden mean number is intrinsically random, letting all measurements in the physical universe fundamentally uncertain. The present analysis offers an explanation of the universal occurrence of the golden mean in diverse natural and biological processes.

Occupational drudgery in tractor operation

Abstract: A study was carried out during 1995–97 and observations pertaining to occupational drudgery occurring in tractor operations were collected by having interaction with 100 drivers employed on tea gardens in Assam. The study revealed that workers of 21–40 years of age preferred tractor driving. The subsoiling needed maximum concentration and alertness. The headache felt by elderly tractor drivers could be minimized by using eye lenses. The study also revealed that tractor driving should not be performed with empty stomach. The duration of continuous operation of different practices by tractor was not significantly influenced by age of drivers.

Weak discontinuities in electrically conducting and radiating gases

Abstract: The singular surface theory has been used to determine the law of propagation of weak discontinuities and the problem of growth and decay of waves. The effect of radioactive heat transfer has been treated using a differential approximation which is valid over entire optical depth range. The effects of wave geometry and magnetic field with finite electrical conductivity on the global behavior of the wave amplitude have also been studied. The two cases of diverging and converging waves have been discussed separately.