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Manu, S.
- Schumann Resonances Observed at Maitri, Antarctica:Diurnal Variation and its Interpretation in Terms of Global Thunderstorm Activity
Authors
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN
Source
Current Science, Vol 109, No 4 (2015), Pagination: 784-790Abstract
Schumann resonances (SRs) are the AC components of the global electric circuit and are excited by the lightning activity within the Earth-ionosphere waveguide. An induction magnetometer, which was operated from the Indian Antarctic station, Maitri (70.8°S, 11.7°E), served to examine the SR parameters, namely the amplitude and frequency, in the north-south (HNS) and east-west (HEW) magnetic components. The analysis for the first resonant mode presented in this work reveals a strong UT variation in its amplitude in seasonal as well as yearly timescales. The NS amplitude reveals a semi-diurnal variation with peaks at ~1000 and ~2100 UT, whereas the EW amplitude exhibits a strong diurnal variation with a pronounced peak at 1600 UT. The diurnal curves for the frequency for both components are similar in nature to those for the amplitude, but for a time shift. The diurnal trend in the amplitude is retained irrespective of seasons, whereas significant difference are noticed in the frequency behaviour between the summer and winter seasons, especially in the EW component. The observed diurnal variation in the SR intensity is explained in terms of the dominant thunderstorm activity centred over the three convectively active regions: Asia/Maritime Continent (Indonesia), South America and Africa. The diurnal variation in frequency depends not only on the location of the thunderstorm region with respect to the observer, but also on the ionospheric day/night conditions and the Earth-ionosphere cavity thickness.Keywords
Diurnal Variations, Global Electric Circuit, Lightning, Schumann Resonances.- A Differential Electrometer for Vector Electric Field Measurements on a Balloon Platform
Authors
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN
Source
Current Science, Vol 111, No 4 (2016), Pagination: 624-626Abstract
Vector measurements of middle atmospheric electric fields are mostly carried out using a double-Langmuir probe technique on platforms like balloons and rockets. High impedances (up to 1013 ohms) and low signal levels (~few millivolts) are the factors that are to be considered in the design of an electrometer for one such experiment. Here, we offer a simple circuit concept that invokes an instrumentation amplifier capable of meeting our several needs, namely generating the guard voltage, ultra-high impedance (1015 ohms) input terminals, femtoampere bias current, differencing, gain setting, etc. all in one package. A three-channel differential electrometer was developed based on this concept and flown on a high-altitude balloon platform. Results reveal that the instrument is capable of detecting weak electric field variations at stratospheric altitudes.- Optimization Lithium Bromide (LiBr)–Water Absorption Refrigration using Taguchi for Low Capacity
Authors
1 Department of Thermal Engineering, SSIT, Tumkur – 572105, Karnataka, IN
2 Department of Mechanical Engineering, MITE, Mangalore – 574225, Karnataka, IN
3 Department of Mechanical Engineering, AMCEC, Bangalore – 560011, Karnataka, IN
Source
Indian Journal of Science and Technology, Vol 9, No 45 (2016), Pagination:Abstract
The study attempts to optimize the parameters for LiBr –water absorption refrigeration system using Taguchi. The investigation was carried out to optimize the Coefficient of Performance (COP) for heat removal of 100W. The three factors considered were: Generator Temperature (Tg), Condenser Temperature (Tc), Absorber Temperature (Ta), Evaporator Temperature (Te). at three different levels. The L9 orthogonal array was selected and the best optimum conditions were identified based on Signal to Noise (S/N ratio) ratio, under the clause: larger is the best. The results showed generator temperature contribution is more on COP.Keywords
LiBr-H2O, COP, Taguchi.- A New Method to Determine the Concentration for LiBr Solution in Vapor Absorption Refrigeration System
Authors
1 Department of Mechanical Engineering, SSIT, Tumkur, Karnataka, IN
2 Department of Mechanical Engineering, MITE, Tumkur, Karnataka, IN
3 Department of Mechanical Engineering, AMCE, Bangalore, Karnataka, IN
Source
International Journal of Innovative Research and Development, Vol 5, No 11Sp (2016), Pagination: 62-64Abstract
The growth in industrialization and improvement in the science technology has developed a new system for the sophistication for the mankind. According to ASHRAE reported more than 50% of the generated power is consumed by the refrigeration and Air-conditioning systems. This resulted in the energy crisis and attributed to development novel systems like vapour absorption refrigeration system. LiBr-H2O (Lithium Bromide-water) vapour absorption refrigeration system showed the promising solution because it uses heat energy to run the system and also it uses natural refrigerant as water due to this there is no detrimental effect on the environment. The key components of this system are generator and absorber and there it is necessary to maintain required concentrations if not resulting in scaling in the line. The literature review showed that, conventional methods are used to determine the concentration. In this regard, the paper attempts to develop the new method to measure the concentration quickly, accurately and at low cost by using conductivity under ambient conditions. The results showed the accuracy in the measurement on compared with conventional method.
Keywords
Lithium Bromide, Concentration, Heat Pump, Conductivity.- Influence of Design Parameters on Heat Transfer Coefficient during Flow Condensation in Pipe Using Taguchi Approach
Authors
1 Department of Mechanical Engineering, Sri Siddhartha Institute of Technology, Tumkur, Karnataka, IN
2 Department of Industrial Engineering & Management, Sri Siddhartha Institute of Technology, Tumkur, Karnataka, IN
Source
International Journal of Innovative Research and Development, Vol 5, No 11Sp (2016), Pagination: 186-188Abstract
The optimization of design parameters is the important step in the Taguchi Method which uses the orthogonal array to maximize the effect of controllable parameters and to minimize the effect of uncontrollable process parameters. This study presents the optimum design parameters on heat transfer coefficient of flow condensation in the pipe using Taguchi method. The investigation was carried out to optimize the heat transfer coefficient (h) for flow condensation. The three factors were considered: Diameter (d), Pressure (P), Mass flux (G) at three different levels. The L9 orthogonal array was selected and the best optimum conditions were identified based on Signal to Noise (S/N) ratio under the characteristic of larger is the best. The results showed Mass flux contribution is more on heat transfer coefficient.