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The present study deals with natural stilbite zeolite commonly named as Ca-stilbite. Ion exchange process is carried out for partial exchange of calcium ions by copper ions. Ion exchanged stilbite is characterized by different spectroscopic techniques as XRD, FTIR and EDS techniques. Thick films are deposited on pre-cleaned glass substrates using screen printing technique. The sintered films are finally used for ethanol detecting. The Ca-stilbite zeolite structure is confirmed by the characterization techniques XRD and FTIR. Incorporation of copper ions in stilbite structure can be confirmed by EDS data. The Cu-stilbite films showed good ethanol detectors. The operating temperature, ethanol response, response/recovery nature are observed to be the functions of concentration of copper ions. Higher the copper concentration (0.2M) lower is the operating temperature (90°C) and higher is the ethanol sensitivity (233). It can be concluded that partial replacement of calcium by copper ions in stilbite leads to change in operating temperature and sensitivity.

An investigation was carried out at experimental block, College of Horticulture, Mudigere. Tropical recorded maximum LAI 2.83, and had maximum plant height, number of leaves, leaf area and Leaf area Index. Cultivar Crinkle Red recorded maximum number of flowers per plant per year (13.14), which was on par with Tropical (11.77), Cheers (10.60) and Fire (10.25). Cultivar Midori recorded maximum vase life (35.00 days) followed by Tropical (33.33 days) and it was on par with Fire (32.22 days). Cultivar Midori recorded maximum vase life (35.00 days), followed by Tropical (33.33 days) and it was on par with Fire (32.22 days) and highest B:C ratio is recorded in cultivar Tropical (1.83) and it was least in Fantacia (1.13) .

Microprocessor based firing control scheme of static slip energy recovery (SER) controlled slip ring induction motor drive is described. In the scheme the microprocessor generates firing pulses and also decides the pair of thyristors of the controlled converter to be gated. It uses less number of hardware components. The oscillograms at different points of the firing circuit and at the output of the controlled converter are presented. These oscillograms resemble with the theoretical wave forms.

Distribution network planning identifies the least cost network investment that satisfies load growth requirements without violating any system and operational constraints. Power injections from distributed generation change network power flows, modifying energy losses. Determining appropriate location and optimal size of distributed generation with respect to network configuration and load distribution in the feeder is main challenge in the changing regulatory and economic scenarios. Among the benefits of distributed generation is the reduction in active power losses, which can improve the system performance; reliability, and efficiency. In this article, the multi-location distributed generation placement problem aims to minimize the total active power loss of radial distribution networks using a genetic algorithm based solution algorithm. This technical benefit of energy savings due to the reduction in active power loss can also be translated into economic benefits. The loss sensitivity to the ...

The distributed generation (DG) is one of the viable options for mitigation of problems of load growth, overloading of lines, quality of supply and reliability in tern extending equipment maintenance intervals and to reduce line losses. However, the line loss reduction is the obvious parameter easily expressible in terms of system parameters. Therefore, this paper aims to minimize active power loss by placing DG strategically in a radial distribution system. The problem is formulated as an optimization problem and solution is obtained using genetic algorithm (GA). The strategic locations are decided on the basis of loss sensitivity to active power injection at various nodes. This approach helps in reducing the computational efforts of selecting appropriate location(s). The performance of the method is tested on 33-bus test system and comparison of the results with a reported method reveals that the proposed method yields superior results. In addition, long term economic benefit of optimal DG placement is also demonstrated. Keywords: distributed generation, line loss reduction, optimal location, radial distribution networks.

The design of microprocessor based slip power recovery controlled slip ring induction motor is described. The Intel-8085 microprocessor is used to implement speed and current controllers and to generate firing pulses. The motor converter system is modeled in z-domain by using small perturbation around the operating point and the transfer function of the system is obtained. The stability of the system is studied by using Jury's stability criterion and the design of current and speed controllers is carried out for the good dynamic response. The effects of controller parameters on the dynamic response of the system are studied.

This paper presents a method for predicting the performance of a dc separately excited motor fed by a load dependent chopper under regenerative braking operation. The method takes into account the effect of commutation time by approximating the area of armature current versus commutation time characteristic as a trapezoid. The effect of armature reaction has also been included. The performance of the motor predicted by this method has been compared with that obtained by digital simulation and shows a close agreement. The performance has also been calculated using constant current method (current at the end of duty interval is assumed constant during commutation interval). It is seen that this method is accurate only at higher values of armature current and results in large errors at its lower values. The effect of filter inductance on the performance of the motor has been studied in detail. A method is developed to predict the value of filter inductance to eliminate discontinuous conduction zone....

This paper describes the transient response of a chopper fed dc separately excited motor using time ratio control. An approximate second order model for predicting the transient behaviour of the motor is developed using perturbation technique. The transient response for small and sudden variations of duty interval and load torque is deduced during discontinuous and continuous current mode operations. The effect of external inductance on the performance of motor in the armature circuit has also been investigated. The results are compared with those obtained from a digital computer by numerically solving the simultaneous differential equations valid for different intervals of chopper cycle and also with the first order model. It is shown that the second order model is more accurate than the first order model and much simpler and efficient than the numerical approach. The theoretical results obtained are also verified with an experimental set up. Experimental results closely agree with theoretical p...

In this paper a frequency domain method has been proposed for the design of LC output filter for a chopper fed dc separately excited motor. The design is based on reducing the dominant harmonic in the armature voltage and armature current of motor, below a specified level, and thereby controlling the ripples in armature voltage and current. The performance of motor with LC output filter is compared with that of without filter during steady and transient states. The effect of commutation time of chopper on the performance of the motor has been included. The concept of binary variables is used for simulating the switching devices for automatic formulation of network equations at mode change over points. It is found that the LC output filter improves the performance by eliminating the discontinuous current zone. The settling time of the transient response of the motor with filter is slightly larger than that of without filter in continuous current region. The computed results are compared with those obtained experimentally and found in close agreement. The efficiency of motor with and without filter has also been compared.

This paper describes a method to estimate the value of a critical inductance for a dc separately excited motor fed by load dependent chopper to eliminate the discontinuous conduction of armature current. A trapezoid approximation has been used to estimate the value of the commutation time of the chopper. To verify the suitability of the method, the performance equations corresponding to different intervals of a chopping cycle are solved numerically on a digital computer. The value of critical inductance has also been obtained using the method developed for rectangular wave chopper. It is found that the proposed method predicts more accurate value of the critical inductance than that of a rectangular wave chopper. It is also seen that a much larger value of the inductance is needed to eliminate the discontinuous conduction in dc separately excited motor fed by load dependent chopper than using rectangular wave chopper.

This paper describes a new method for evaluating the steady state and dynamic responses of a dc separately excited motor fed by load dependent chopper using time-ratio control (TRC). The proposed method takes into account the effect of commutation time and armature reaction. The area of armature current versus time characteristics during commutation interval is approximated by a trapezoid rather than a rectangle as in the constant current method. This method is applicable to both continuous and discontinuous current modes of operation. The results of this method are compared with those obtained from a digital computer by numerically solving the simultaneous differential equations valid for different intervals of chopper cycle, the constant current method and by experimental set up. The results show a close agreement with the exact solution by digital computer and experimental values.