Design and development of five-channel interference filter polychromator for SST-1 Thomson scattering system

Five-channel interference filter polychromator is designed and fabricated for measuring electron temperature and density from Thomson scattered spectrum of SST-1 tokamak plasma. The instrument is designed for measuring electron temperature in the range of 20 eV-3 keV and electron density of 10¹⁸-10¹⁹ m⁻³. Optical ray tracing software, Zemax is used for simulating and optimizing the optical design. Each polychromator is a stand-alone unit with field programmable gate array (FPGA) based controller unit for easy operation, monitoring of the temperature variation of the instrument and communicating to a central personal computer (PC). The control unit also protects the avalanche photo diode (APD) detectors from damage due to high current flow, sets the slow channel gain and switches on the biasing power supply. Characteristics of the present polychromator design are relatively high signal throughput and variable bandwidth selection of filters combined with a stable, low cost and relatively simple configuration. Filter selection, arrangement order of filters, statistical error analysis, mechanical and optical design and estimation of electron temperature and density are discussed in this article. The fabricated filter polychromator is tested for its image quality, optical alignment, and integrated performance.     

Effects of RNA, purines and pyrimidines on the development of Tribolium confusum (Duval)

Growth period and survival of Tribolium confusum were studied on a chemically defined diet alone or supplemented with RNA; guanine, adenine, cytosine, and uracil were also added to the basic diet either singly or in all possible combinations. The effect of supplementing a processed food (dehydrated tapioca pudding) with various levels of RNA on the growth and survival of the beetle was also studied.

Diets supplemented with RNA or a mixture of guanine + cytosine or all the four nucleotides were equally effective in stimulating growth and increasing survival of the beetle; guanine + adenine also improved the diet but not as well as the other three. In general, the purines guanine and adenine stimulated the growth and the pyrimidine cytosine acted as synergist while uracil had slight retardatory effect. The tapioca pudding, which is inadequate for supporting growth of the beetle was also improved by the addition of RNA.     

Impurity Alkali Diffusion in Sodium-Cesium Silicate Glasses

The tracer diffusion coefficient of ⁸⁶Rh was measured as a function of Cs/Na ratio in (Na, CS)₂O:3SiO₂ glasses. A comparison of the compositional dependence of this impurity alkali diffusion with the self-diffusion coefficients of ²²Na and ¹³⁷Cs suggests that the alkali-ion pair concept in the weak-electrolyte model is not sufficient to explain the mixed-alkali effect.     

EARTHQUAKE RESPONSE OF STRENGTHENED STEEL SPECIAL MOMENT RESISTING FRAMES

This paper presents the response of steel moment resisting frames with damage to their welded connections for two repair options: (1) reweld only; and (2) reweld and strengthen connection. Two different nonlinear dynamic analysis programs are used to research the effect of repairing and strengthening these weld failures and also for predicting the expected building response assuming that the connection is not repaired. The effect on response is studied for connections where weld failure reduces the capacity to 50, 20 and 5% of the original moment capacity. The frames selected for the research are in a real building damaged during the Northridge earthquake. They are subjected to an ensemble of artificial earthquake records that have an equal probability of occurring at the site for comparative studies. © 1997 John Wiley & Sons, Ltd.     

Steady-state modelling of hybrid energy system for off grid electrification of cluster of villages

Electrification of villages from the main grid leads to large investments and losses, and this forms the basis of decentralized Hybrid Energy System. In order to evaluate the techno-economic performance of hybrid energy system for remote rural area electrification, a mixed integer linear mathematical programming model (time-series) has been developed to determine the optimal operation, optimal configuration including the assessment of the economic penetration levels of photovoltaic array area, and cost optimization for a hybrid energy generation system consisting of small/micro hydro based power generation, biogas based power generation, biomass (fuelwood) based power generation, photovoltaic array, a battery bank and a fossil fuel generator. An optimum control algorithm written in C++, based on combined dispatch strategy, allowing easy handling of the models and data of hybrid energy system components is presented. A special feature of the proposed model is that a cost constant (cost/unit) for each of the proposed resource is introduced in the cost objective function in such a way that resources with lesser unit cost share the greater of the total energy demand in an attempt to optimize the objective function.To demonstrate the use of model and algorithm, a case study for a rural remote area is also presented.     

Investigations into the effect of cathode material on temperature distribution during electrochemical machining

Electrochemical machining (ECM) is one of the most widely used unconventional manufacturing processes. Its capabilities have not been fully exploited mainly because of some inherent problems associated with tool design. Most of the models available for tool design in ECM ignore the effect of the heat transferred through the cathode and anode and its effects on the variation of different process parameters during ECM.

In the present paper, a simple thermal-resistance model of the ECM process is proposed. Using this model, the effects of the heat transferred through electrodes on temperature distribution, electrolyte conductivity, anode profile, metal removal rate (MRR), etc. have been studied. The experimental data have then been used to test the accuracy of the model.

The tests show that, for accurate determination of the anode profile, any model which takes no account of the heat transferred through the electrodes will yield erroneous results.     

Cotton yield estimation using agrometeorological model and satellite-derived spectral profile

Timely and accurate estimates of district-level cotton yield are essential for management decisions related to the cotton economy of a country. Surendranagar is a major cotton growing district of Gujarat, India. The yield of cotton for Surendranagar district was estimated using (i) a linear time series trend and actual evapotranspiration (AET) based model for irrigated cotton and an empirical model between the AET and the yield for unirrigated cotton; and (ii) the NDVI (Normalized Difference Vegetation Index) spectral profile area, using data from the LISS I sensor on-board the Indian Remote Sensing (IRS) satellite. AET was estimated using a simple agrometeorological soil moisture balance model for 11 years (1983-1993). The cotton lint yield estimates from the above two different approaches had a 1.2% relative deviation between them and differed by -14.4 and -13.1%, respectively, from the yield estimates given by the Department of Agriculture, Gujarat.