Optical Diagnostics Study of Gas Particle Transport Phenomena in Cold Gas Dynamic Spraying and Comparison with Model Predictions

Cold gas dynamic spraying (CGDS), a relatively new thermal spraying technique has drawn a lot of attention due to its inherent capability to deposit a wide range of materials at relatively low-operating temperatures. A De Laval nozzle, used to accelerate the powder particles, is the key component of the coating equipment. Knowledge concerning the nozzle design and effect of process parameters is essential to understand the coating process and to enable selection of appropriate parameters for enhanced coating properties. The present work employs a one-dimensional isentropic gas flow model in conjunction with a particle acceleration model to calculate particle velocities. A laser illumination-based optical diagnostic system is used for validation studies to determine the particle velocity at the nozzle exit for a wide range of process and feedstock parameters such as stagnation temperature, stagnation pressure, powder feed rate, particle size and density. The relative influence of process and feedstock parameters on particle velocity is presented in this work.     

Relating Trends in Streamflow to Anthropogenic Influences: A Case Study of Himayat Sagar Catchment,India

Catchment development has been identified as a potentially major cause of streamflow change in many river basins in India. This research aims to understand changes in the Himayat Sagar catchment (HSC), India, where significant reductions in streamflow have been observed. Rainfall and streamflow trend analysis for 1980–2004 shows a decline in streamflow without significant changes in rainfall. A regression model was used to quantify changes in the rainfall-runoff relationship over the study period. We relate these streamflow trends to anthropogenic changes in land use, groundwater abstraction and watershed development that lead to increased ET (Evapotranspiration) in the catchment. Streamflow has declined at a rate of 3.6 mm/y. Various estimates of changes in evapotranspiration/irrigation water use were made. Well inventories suggested an increase of 7.2 mm/y in groundwater extractions whereas typical irrigation practices suggests applied water increased by 9.0 mm/y, while estimates of evapotranspiration using remote sensing data showed an increasing rate of 4.1 mm/y. Surface water storage capacity of various small watershed development structures increased by 2 mm over 7 years. It is concluded that the dominant hydrological process responsible for streamflow reduction is the increase in evapotranspiration associated with irrigation development, however, most of the anthropogenic changes examined are interrelated and occurred simultaneously, making separating out individual impacts very difficult.     

Concentric Ring Structured Reconfigurable Antenna using MEMS Switches for Wireless Communication Applications

Wireless Personal Communications - This paper proposes a reconfigurable circular microstrip antenna to serve the wireless communication applications that make use frequency bands such as ISM...     

Evaluation of distilling the entire digest or an aliquot for total nitrogen determination in soil digests

Accurate and easy to adapt methods of total soil N determination are a prerequisite for N balance research. For¹⁵N balance studies certain modifications of the regular methods are generally adopted, e.g. the distillation of an aliquot of the digest in preference to the entire digest. However, comparative evaluation of such methods has not been investigated. In this study, three methods of distilling soil digests were evaluated for the determination of total N in diverse Alfisols and Vertisols. These are distillation of a clear aliquot (suspended materials allowed to settle) of the digest, distillation of an aliquot with suspended materials, following digestion in a block digestor, and distillation of the entire digest following macro-Kjeldahl digestion. The total N content of soils were determined to be similar whether the aliquot distilled was a clear solution or a suspension with solid materials, and these results were similar to those obtained by distilling the entire digest. The precision obtained by the three methods of distillation was similar for the Vertisols but for the Alfisols, distillation of the clear aliquot of the digest was found to be most precise.Submitted as Journal Article No. 776 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)     

Relationship between extracted phosphorus and sorghum yield in a Vertisol and an Alfisol under rainfed cropping

Little attention has been devoted to calibrating the soil tests for P in the field for crops grown under rainfed conditions in different soil types. Field experiments were conducted during the 1990 rainy season (June-September) at the ICRISAT Center, Patancheru (near Hyderabad), India on nearby Vertisol and Alfisol sites having a range in extractable P, for establishing relationships between extractable P and sorghum yield.In the Vertisol, 90% relative grain yield of sorghum was obtained at 2.8 mg kg^–1 Olsen extractable P while in the Alfisol, 90% relative grain yield was achieved at 5.0 mg P kg^–1 soil. These results suggest that a single critical limit of available P does not hold true for grain sorghum in the two soil types under similar agroclimatic conditions and that the critical limit is lower for the clayey Vertisol than the sandy Alfisol.