Informatics Publishing Limited

B. S. Bisht ¹, P. Rajasekaran ¹, R. M. Sinha ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research Department of Atomic Energy, Begumpet, Hyderabad- 500016, IN

Abstract

Aqueous bi-phase fluid inclusions in quartz from mineralised vein, granite and pebbly quartzite have been studied to decipher physico-chemical conditions of the unconformity-related uranium mineralisation at Lambapur- Peddagattu area in the northern fringe of Cuddapah basin. Fluid inclusions in vein- and granitic- quartz show significant similarity in phase ratios and homogenisation temperatures, though they differ in the mode of origin. main population of inclusions in vein quartz is of primary origin, while in granitic quartz it is of secondary origin. The size of fluid inclusions generally varies between lOpm to 20pm, with low gas to liquid ratios corresponding to high degree of fill (F=0.8 to 0.9). Inclusions in vein- and granitic- quartz homogenise to liquid phase between 140°C to 240°C (mode 150°C to 170°C) [T_H]. Similar temperature of homogenisation has been obtained in quartz of pebbly quartzite. The ice melting temperatures in vein quartz are in the range of -2°C to - 10°C [T_M] equivalent to salinity of 1-14 wt% eNaCl and in granitic quartz these are in the range of -6°C to -14"C[T_M] corresponding to salinity values of 10-18 wt% eNaC1. The low temperature fluid inclusions homogenising at similar range of temperatures but showing variable salinity suggest mixing of isothermal fluids of contrasting salinity. It is likely that uranium precipitated from the interaction of cooling low saline hydrothermal solution at the temperatures of 150-170°C with high saline mineralising fluid transported by recirculating meteoric water.

Keywords

Fluid Inclusions, Microthermometry, Uranium Mineralisation, Cuddapah Basin, Andhra Pradesh.

Full Text

     

P. Rajasekaran ¹, V. Jawahar Senthilkumar ²

Affiliations
1 Department of Electrical and Electronics Engineering, Jawaharlal Nehru Technological University, Hyderabad - 500085, Telangana, IN
2 Department of Electronics and Communication Engineering, Anna University, Chennai –600025, Tamil Nadu, IN

Abstract

This paper presents the comparative analysis of various level of multilevel inverter for induction motor torque ripple minimization. The neutralpoint clamped (NPC) inverter is used an adequate solution in AC drives application. The Conventional inverters compared to multilevel inverters have many limitations in high-voltage and high-power applications like poor power quality, high voltage stress, EMI/EMC issue etc. Also proposed the Space Vector neutral point clamped inverter for Torque ripple reduction in induction drive. The Simple Space vector control scheme is applied to neutral point clamped inverter by reference torque estimation. In this proposed topology offer an improved performance in the form of torque ripple reduction scheme. The Classical direct torque control of two-level VSI scheme is compared with proposed three-level NPC scheme. The main aim of this paper to provide a significant method and control scheme to obtained torque ripple reduction in induction motor Drive. The result shows the performance of neutral point clamped inverter using CB-PWM on induction drive. In this paper three levels VSI based Neutral Point Clamped (NPC) multilevel inverter fed induction motor drive is simulated, analyzed and compared with two levels VSI based NPC inverter drives. Torque of the motor is controlled by using space vector based direct torque control (DTC) method. The simulation results are carried out by using MATLAB/SIMULAINK environment.

Keywords

Direct Torque Control (DTC), Induction Drive, Multilevel Inverter, Neutral Point Clamped Inverter (NPC), Space Vector Pulse Width Modulation (SVPWM), Torque Ripple, Voltage Source Inverter (VSI)

Full Text