Enhanced Room Temperature Coefficient of Resistance and Magneto-resistance of Ag-added La0.7Ca0.3-xBaxMnO3 Composites

In this paper we report an enhanced temperature coefficient of resistance (TCR) close to room temperature in La0.7Ca0.3-xBaxMnO3 + Agy (x = 0.10, 0.15 and y = 0.0 to 0.40) (LCBMO+Ag) composite manganites. The observed enhancement of TCR is attributed to the grain growth and opening of new conducting channels in the composites. Ag addition has also been found to enhance intra-granular magneto-resistance. Inter-granular MR, however, is seen to decrease with Ag addition. The enhanced TCR and MR at / near room temperature open up the possibility of the use of such materials as infrared bolometric and magnetic field sensors respectively.Comment: 22 pages of Text + Figs:comments/suggestions([email protected]

Young Stellar Population of the Bright-Rimmed Clouds BRC 5, BRC 7 and BRC 39

Bright-rimmed clouds (BRCs), illuminated and shaped by nearby OB stars, are potential sites of recent/ongoing star formation. Here we present an optical and infrared photometric study of three BRCs: BRC 5, BRC 7 and BRC 39 to obtain a census of the young stellar population, thereby inferring the star formation scenario, in these regions. In each BRC, the Class I sources are found to be located mostly near the bright rim or inside the cloud, whereas the Class II sources are preferentially outside, with younger sources closer to the rim. This provides strong support to sequential star formation triggered by radiation driven implosion due to the UV radiation. Moreover, each BRC contains a small group of young stars being revealed at its head, as the next-generation stars. In particular, the young stars at the heads of BRC 5 and BRC 7 are found to be intermediate/high mass stars, which, under proper conditions, may themselves trigger further star birth, thereby propagating star formation out to long distances.Comment: 30 pages, 7 Figures, 6 Tables, accepted for publication in Monthly Notices of the Royal Astronomical Societ

Growth of dense CNT on the multilayer graphene film by the microwave plasma enhanced chemical vapor deposition technique and their field emission properties

Catalyst assisted carbon nanotubes (CNTs) were grown on multilayer graphene (MLG) on copper and silicon substrates by the microwave plasma enhanced chemical vapor deposition technique. The transmission of the MLG was found to vary between 82 to 91.8% with the increase of deposition time. Scanning electron microscopy depicted that the MLG film survived at the deposition condition of CNTs with the appearance of the damaged structure due to the plasma. Growth of CNTs was controlled by adjusting the flow rates of methane gas. The density of carbon nanotubes was observed to increase with a higher supply of methane gas. It was observed that the field emission properties were improved with the increased density of CNTs on MLG. The lowest turn-on field was found to be 1.6 V mu m(-1) 1 accompanied with the highest current density of 2.8 mA cm(-2) for the CNTs with the highest density. The findings suggested that the field emission properties can be tuned by changing the density of CNTs

Growth modelling and forecasting of common carp and silver carp in culture ponds: A re-parametrisation approach

The available forecasting models for growth pattern in fish are based on either classical approach or a particular growth model. In the present study, reparamerisation methodologies were attempted for forecasting growth of fish cultured in cemented ponds of plain areas. Forecasting methodology is not readily available for any other types of ponds for uplands of India. So, other appropriate growth curves (Logistic, Gompertz and von-Bertalanffy) were considered while developing the most suitable model for forecasting fish (common carp Cyprinus carpio var communis and silver carp Hypophthalmichthys molitrix) production from cemented ponds. Gompertz-1 and Logistic-1 models gave the best fit as well as fish yield forecasting, two months ahead from various ponds

Performance evaluation of yield crop forecasting models using weather index regression analysis

A crop forecast is a statement of the most likely magnitude of yield or production of a crop. It is made on the basis of known facts on a given date and it assumes that the weather conditions and damages during the remainder of the growing season will be about the same as the average of previous year. The present paper deals with use of non-linear regression analysis for developing wheat yield forecast model for Allahabad district (India). A novel statistical approach attempted in this study to use nonlinear models with different weather variables and their indices and compare them to identify a suitable forecasting model. Time series yield data of 40 years (1970-2010) and weather data for the year 1970-71 to 2009-10 have been utilized. The models have been used to forecast yield in the subsequent three years 2008-09 to 2009-10 (which were not included in model development). The approach provided reliable yield forecast about two months before harvest

Pre harvest forecasting of crop yield using non-linear regression modelling: A concept

A reliable and timely forecast of crop production helps in planning, formulation and implementation of policies relating to food procurement, its distribution, price, import and export and for exercising several administrative measures for storage and marketing of agricultural commodities. Thus pre-harvest forecasting of production is required when crop is still standing in the field. An efficient forecasting is thus a pre-requisite for food supply information system at district and state level. The final crop production estimates, though based on objective crop-cutting experiments, are of limited utility as these become available much later after the crop harvest. In view of this, there is a need for developing an objective methodology for pre-harvest forecasting of crop yield..

Wheat yield forecast using detrended yield over a sub-humid climatic environment in five districts of Uttar Pradesh, India

A study was carried out to forecast the yield of the wheat crop for five districts of Uttar Pradesh namely Lucknow, Kanpur, Banda, Jhansi and Faizabad. The daily weather data on variables such as maximum temperature, rainfall, minimum temperature, and relative humidity were arranged week wise from sowing to harvesting and the relations between the weather variables and yield was worked out using statistical tools like correlation and regression. The yield has been detrended by obtaining the parameter estimates of the model and subsequently the detrended yield was used to forecast the yield of the crop using ARIMA model. The proposed method of obtaining pre-harvest forecasting of yield of crops was compared with the traditional approaches of forecasting and the proposed method was evaluated in terms of criteria’s such as goodness of fit of the model. It was observed that in all the districts the proposed model performed better as compared to the traditional method both in terms of goodness of fit as well as forecasting performance. Thus it can be concluded that the proposed approach is better and more suitable as compared to the traditional approach for forecasting the wheat yield in the five districts of Uttar Pradesh

Measurements of evaporation residue cross-sections and evaporation residue-gated γ\gamma-ray fold distributions for 32^{32}S+154^{154}Sm system

Evaporation Residue (ER) cross-sections and ER-gated $\gamma$-ray fold distributions are measured for the $^{32}$S + $^{154}$Sm nuclear reaction above the Coulomb barrier at six different beam energies from 148 to 191 MeV. $\gamma$-ray multiplicities and spin distributions are extracted from the ER-gated fold distributions. The ER cross-sections measured in the present work are found to be much higher than what was reported in a previous work using a very different target-projectile ($^{48}$Ti + $^{138}$Ba) combination, leading to the same compound nucleus $^{186}$Pt, with much less mass asymmetry in the entrance channel than the present reaction. This clearly demonstrates the effect of the entrance channel on ER production cross-section. The ER cross-sections measured in the present work are compared with the results of both the statistical model calculations and the dynamical model calculations. Statistical model calculations have been performed to generate a range of parameter space for both the barrier height and Kramers' viscosity parameter over which the ER cross-section data can be reproduced. The calculations performed using the dinuclear system (DNS) model reproduce the data considering both complete and incomplete fusion processes. DNS calculations indicate the need for the inclusion of incomplete fusion channel at higher energies to reproduce the ER cross-sections.Comment: 13 pages, 18 figure