A frictional Cosserat model for the flow of granular materials through a vertical channel

A rigid-plastic Cosserat model has been used to study dense, fully developed flow of granular materials through a vertical channel. Frictional models based on the classical continuum do not predict the occurrence of shear layers, at variance with experimental observations. This feature has been attributed to the absence of a material length scale in their constitutive equations. The present model incorporates such a material length scale by treating the granular material as a Cosserat continuum. Thus localised couple stresses exist and the stress tensor is asymmetric. The velocity profiles predicted by the model are in close agreement with available experimental data. The predicted dependence of the shear layer thickness on the width of the channel is in reasonable agreement with data. In the limit of the ratio of the particle diameter to the half-width of the channel being small, the model predicts that the shear layer thickness scaled by the particle diameter grows.Comment: 17 pages, 12 PostScript figures, uses AmsLaTeX, psfrag and natbib. Accepted for publication in Acta Mechanic

Silica based Product Identified for Production from Kimberlite Tailing

National Mineral Development Corporation is involved in diamond mining in the country & Kimberlite produce as a mines waste during kimberlite mining .N M D C is producing around 0.9 million tones of Kimberlite per year in Panna. With estimated life of 20 years for Panna mines , it is pertinent to look for commercial application of kimber-lite . Around 3-4 million tones of Kimberlite is already available from Panna mines accumulated during previous mining . Due to the fact that Kimberlite / Diamond ratio is 100 tones of kimberlite per 10 carat of Diamond produ-ced, there is a need to look for development of multi — product which are of bulk usage from the Kimberlite. Technological option for Eco- friendly & Economically Efficient Utilization of Kimberlite needed and in view of their wide application, also bulk usage, the following three products were identified to be developed from Kimberlite

Antioxidant-Rich Amaranth Varieties, Arka Samraksha and Arka Varna

Amaranth improvement in India hither to was concerned with development of high-yielding varieties, and hardly any research efforts have been made for its nutritional improvement. Keeping this in view, at Indian Institute of Horticultural Research two high-yielding amaranth varieties, Arka Samraksha and Arka Varna with high antioxidant activity, low amounts of nitrates and oxalates were developed using modified bulk method of selection from segregating population of the crosses IIHR-4 x IIHR-70 and IIHR-7 x IIHR-30 . Arka Samraksha is a high-yielding (10.9 t/ha in 30-35 days), pulling-type variety with green leaves and stem, antioxidant activity of 499mg (AEAC units) and minimum nitrate content of 27.3 mg and 1.34 g oxalates per 100 g fresh leaf weight. Arka Varna also a pulling type, high-yielding variety (10.6 t/ha in 30-35 days) with green leaves and a pink stem, high antioxidant activity of 417 mg (AEAC units), low nitrate content of 37.6 mg and 1.42 g oxalates per 100 g fresh leaf weight

Seed nitrogen and fatty acids reflecting yield variation in groundnut (Arachis hypogaea)

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A frictional Cosserat model for the slow shearing of granular materials

A rigid-plastic Cosserat model for slow frictional flow of granular materials, proposed by us in an earlier paper, has been used to analyse plane and cylindrical Couette flow. In this model, the hydrodynamic fields of a classical continuum are supplemented by the couple stress and the intrinsic angular velocity fields. The balance of angular momentum, which is satisfied implicitly in a classical continuum, must be enforced in a Cosserat continuum. As a result, the stress tensor could be asymmetric, and the angular velocity of a material point may differ from half the local vorticity. An important consequence of treating the granular medium as a Cosserat continuum is that it incorporates a material length scale in the model, which is absent in frictional models based on a classical continuum. Further, the Cosserat model allows determination of the velocity fields uniquely in viscometric flows, in contrast to classical frictional models. Experiments on viscometric flows of dense, slowly deforming granular materials indicate that shear is confined to a narrow region, usually a few grain diameters thick, while the remaining material is largely undeformed. This feature is captured by the present model, and the velocity profile predicted for cylindrical Couette flow is in good agreement with reported data. When the walls of the Couette cell are smoother than the granular material, the model predicts that the shear layer thickness is independent of the Couette gap H when the latter is large compared to the grain diameter dp. When the walls are of the same roughness as the granular material, the model predicts that the shear layer thickness varies as (H/dp)1/3 (in the limit H/dp [dbl greater-than sign] 1) for plane shear under gravity and cylindrical Couette flow

High-Yielding Multicut Coriander Variety, Arka Isha

Coriander (Coriandrum sativum L.) is one of the important leafy vegetables having a pleasant aroma. Very little research work has been done on improvement of leafy coriander and only a few local varieties, low-yielding and with low aroma, are available in the market. Research work at Indian Institute of Horticultural Research has resulted in development of a leafy coriander variety, Arka Isha, with a high yield potential and good aroma. It is a multicut variety where the plants are bushy, leaves are broad and leaf lobes are short, and the variety is late flowering. Yield is 3.74t ha-1 by pulling at 40 days after sowing, and 11.98t ha-1 by cutting. Leaves have 167.05mg 100g-1 of Vitamin C, with good aroma and keeping-quality

Effects of ICI 182780 on estrogen receptor expression, fluid absorption and sperm motility in the epididymis of the bonnet monkey

BACKGROUND: The importance of estrogen in regulation of fluid absorption and sperm maturation in the rodent epididymis has been established from studies on estrogen receptor-alpha knockout mice. However, functional studies on the role of estrogen in primate epididymis have been few. The main objective of this study was therefore to extend these observations and systematically analyze the presence and function of estrogen receptors in modulating the function of the primate epididymis, using the bonnet monkey (Macaca radiata) as a model system. METHODS: A steroidal estrogen receptor (ER) antagonist, ICI 182780 (ICI), was administered to adult male bonnet monkeys via mini-osmotic pumps for a duration of 30 to 180 days. The expression of key estrogen-regulated genes (ER-alpha, Na-K ATPase alpha-1 and Aquaporin-1) was examined at specific time points. Further, the effect of ICI in modulating fluid reabsorption in efferent ductules was monitored, and critical sperm-maturation parameters were also analyzed. RESULTS: Our studies in the bonnet monkey revealed that both ER-alpha and ER-beta were expressed in all the three regions of the epididymis. We observed an increase in ER-alpha mRNA and protein in the caput of ICI-treated monkeys. Steady state mRNA levels of the water-channel protein, Aquaporin-1, was significantly lower in the caput of ICI-treated monkeys compared to controls, whereas the mRNA levels of Na-K ATPase alpha-1 remained unchanged. In vitro incubation of efferent ductules with ICI resulted in two-fold increase in tubular diameter, indicating affected fluid reabsorption capacity. Furthermore, sperm from ICI-treated monkeys were immotile. CONCLUSION: Taken together, our results point to an integral role for estrogen in modulating the functions of the bonnet monkey epididymis. This study also demonstrates possible differences in the epididymal physiology of rodents and non-human primates, and thus underscores the significance of reports such as these, that examine the physiology of non-human primates (as opposed to rodents), in an attempt to understand similar events in the human

Radiowave fading at Waltair during I.G.Y

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