An experimental analysis of subcooled leakage flow through slits from high pressure high temperature pipelines

The work presented here is an experimental investigation of the critical flashing flow of initially subcooled water through circumferential slits in pipes. The study provides first hand information about the prediction of leak flow rates in piping and pressure vessels retaining high temperature and high pressure. The dedicated experimental facility loop simulates the thermal hydraulic condition of Pressurized Heavy Water Reactors (PHWR). The critical flow characteristics found for varying leakage cross sections at different stagnation pressure and different degree of subcooling has been demonstrated in this paper. A marked decrease in mass flux has been found as subcooling decreases for a fixed stagnation pressure. More observation has revealed that the tighter slits or openings with very short duct as small as 0.8 cm flow length have different flow behavior than greater opening dimensions or with longer flow channels or that for nozzles. The critical flow has been seen to occur at higher pressure differentials along the flaws and prominent changes in the flow rate is reported to occur with varying dimensional parameters of the slit or cracks.     

Hydrogen from empty cotton boll agro-waste via thermochemical route and feasibility study of operating an IC engine in continuous mode

Hydrogen can be cited as prospective source of clean power. In this work hydrogen rich syn-gas generated from the agro-waste, empty cotton bolls was injected into an IC engine in continuous mode along with gasoline. At the air-fuel ratio of 23.40, specific fuel consumption of 0.35 kg kWh^?1, the engine could be operated with higher efficiency than with gasoline alone. A distinct reduction in emission characteristics could also be seen. Empty cotton bolls derived after removal of cotton from the flower in field, was first studied for fuel properties. The reasonably high heating value (HHV) of 17.54 MJ kg^?1 suggested that it could be a precursor to hydrogen via two stepped thermo-chemical process. The first step involved slow pyrolysis of the biomass at 500 °C for 60 min at a heating rate of 10 °C min^?1 yielding 39.71% bio-char by weight. The C, H, N, S and O contents of the produced bio-char was 59.91, 2.91, 0.72, 0.47 and 35.99% respectively and its HHV was 26.7 MJ kg^?1. Steam gasification of this bio-char, at 700 °C and water flowrate of 7 mL min^?1 exhibited maximum hydrogen yield of 67.42% (v/v) in the syn-gas mixture. Subsequent enrichment of the gas using ethanolamine/ethylene diamine and KMnO₄ solutions resulted in more than 90% (v/v) hydrogen in the combustible gas mixture and the test engine could be effectively operated.     

Effect of vegetarian diets on zinc status: a systematic review and meta‐analysis of studies in humans

Plant‐based diets contain less saturated fat and cholesterol and more folate, fibre and phytochemicals than omnivorous diets, but some micronutrients, especially zinc, are poorly bioavailable. The findings of studies exploring the zinc intake and zinc status in populations that habitually consume vegetarian diets are inconsistent. This study aims to investigate the effects of plant‐based diets on dietary zinc intake and status in humans using systematic review and meta‐analysis techniques. Thirty‐four studies were included in the systematic review. Of these, 26 studies (reporting 48 comparisons) compared males and/or females consuming vegetarian diets with non‐vegetarian groups and were included in meta‐analyses. Dietary zinc intakes and serum zinc concentrations were significantly lower (?0.88 ± 0.15 mg day^?1, P < 0.001 and ?0.93 ± 0.27 µmol L^?1, P = 0.001 respectively; mean ± standard error) in populations that followed habitual vegetarian diets compared with non‐vegetarians. Secondary analyses showed greater impact of vegetarian diets on the zinc intake and status of females, vegetarians from developing countries and vegans. Populations that habitually consume vegetarian diets have low zinc intakes and status. Not all vegetarian categories impact zinc status to the same extent, but a lack of consistency in defining vegetarian diets for research purposes makes dietary assessment difficult. Dietary practices that increase zinc bioavailability, the consumption of foods fortified with zinc or low‐dose supplementation are strategies that should be considered for improving the zinc status of vegetarians with low zinc intakes or serum zinc concentrations at the lower end of the reference range. © 2013 Society of Chemical Industry     

Image feature based high capacity steganographic algorithm

Multimedia Tools and Applications - Steganography is the growing field of research, where hiding techniques are used to secure the communicative elements (e.g., images). In this paper, the message...     

Conceptual design and study of high precision translational stages: application to an optical delay line

This paper describes some aspects of the design approach anti modeling of an optical delay line for the east-west stellar interferometer of the Observatoire de la Côte d'Azur (OCA) in France. The optical delay line with a long stroke of 3 m, has been designed with two stages. All upper stage is supported by aerostatic porous media bearings on a lower stage that travels on rollers. Interstage decoupling has been matched to achieve the required stability for the high-precision upper stage. Guidelines with theoretical analysis and experimental results are presented. A theoretical model for the assembled svstcm has been developed, taking into account the rolling contact and the (list urbances induced Iby microasperities on the tracks. The natural frequencies have been determined with the bearings characteristics necessary to meet requirement specifications. Experimental results show good agreement with the requirements. Moreover, analytic modeling and finite element modeling (FEM) analysis seem to be good tools for predicting movement at the nanometer level, even with high loads and long strokes.     

Palladium‐Mediated Labeling of Nucleic Acids

New applications of Pd‐catalyzed coupling reactions (Suzuki–Miyaura, Sonogashira, and Stille–Migita coupling) for post‐conjugation of nucleic acids have been developed recently. Breakthroughs in this area might now pave the way for the development of sophisticated DNA probes, which might be of great interest in chemical biology, nanotechnology, and bioanalysis, as well as in diagnostic domains.     

Performance of dead reckoning‐based location service for mobile ad hoc networks

A predictive model‐based mobility tracking method, called dead reckoning, is developed for mobile ad hoc networks. It disseminates both location and movement models of mobile nodes in the network so that every node is able to predict or track the movement of every other node with a very low overhead. The basic technique is optimized to use ‘distance effect’, where distant nodes maintain less accurate tracking information to save overheads. The dead reckoning‐based location service mechanism is evaluated against three known location dissemination service protocols: simple, distance routing effect algorithm for mobility (DREAM) and geographic region summary service (GRSS). The evaluation is done with geographic routing as an application. It is observed that dead reckoning significantly outperforms the other protocols in terms of packet delivery fraction. It also maintains low‐control overhead. Its packet delivery performance is only marginally impacted by increasing speed or noise in the mobility model, that affects its predictive ability. Copyright © 2004 John Wiley & Sons, Ltd.     

Lignocellulosic polymer composite IV

Palm leaves as a woody lignocellulose, together with polystyrene, were used to produce composites. Chemithermal mechanical pulps (CTMP) were obtained from palm leaves under alkaline or acidic conditions. Appropriate bending strength was obtained from palm leaves and their CTMP pulps prepared under neutral or acidic conditions. The bulky fibers resulted from the alkaline pulps lead to composites of low bending strength. Thus, the cooking conditions of the palm leaves to obtain CTMP pulp play an important role on the properties of the composites. The nonbulky fibers lead to the formation of trapped pockets air as the number of the hydrogen bond are few. The presence of these air pockets allows the polystyrene solution to enter forming bonding between the interfaces. It is also found that the lower the density of the composites, the lower the internal bond strengths. The chemical constituents of the CTMP pulps, as well as the yields of the pulps, may influence the properties of the composites. Increasing the percentage of polystyrene in the composites, the mechanical properties increased. The water uptake and the swellability decreased until 20% polystyrene concentration and then levelled off. The thickness and density behaved the same. However, the type of substrate of the composite and the weight fraction are the important factors in determining the properties of the composites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 845–855, 1998