499,981 research outputs found

    Tilting Rightward: C-SPAN's Coverage of Think Tanks

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    This study's main finding is that C-SPAN coverage of think tanks overwhelmingly favors conservative think tanks while left-of-center think tanks are under-represented. In 2006, conservative think tanks received 43.76 percent of total think tank coverage. Conservative/ libertarian and centrist think tanks received 6.94 percent and 31.76 percent respectively. Center-left and progressive think tanks, on the other hand, only received 12.73 percent and 4.86 percent respectively. Thus, the combined conservative and conservative/libertarian think tanks got an absolute majority of 50.7 percent representation on C-SPAN. Everything left of center got only 17.59 percent, just one third of the coverage received by the Right

    Experimental study of temperature stratification in an integrated collector-storage solar water heater with two horizontal tanks

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    The effect of tank-interconnection geometry on temperature stratification in an integrated collector-storage solar water (ICSSW) heater with two horizontal cylindrical tanks has been studied. The tanks were parallel to each other, and separated horizontally and vertically, with the lower tank fitted directly below a glass cover, and half of the upper tank insulated. In addition, a truncated parabolic concentrator was fitted below the tanks, with its focal line along the axis of the upper tank. The heater was tested outdoors with the two tanks connected in parallel (P), and S1-and S2-series configurations, with and without hot water draw-off. Water temperature was monitored during solar collection and hot water draw-offs. For the heat charging process, it was found that only the lower tank exhibited temperature stratification in the P-and S1-tank modes of operation. There was satisfactory temperature stratification in both tanks in the S2-tank configuration. For the hot water draining process, the P-tank configuration exhibited some degree of stratification in both tanks. A significant loss of stratification was observed in the lower tank, with the upper tank exhibiting practical stratification, when the system was operated in the S1-tank mode. The S2-tank interconnection maintained a satisfactory degree of temperature stratification in both tanks. So, the S2-tank mode of operation was most effective in promoting practical temperature stratification in both tanks during solar collection and hot water draw-offs. Other results are presented and discussed in this paper

    Preformed stiffeners used to fabricate structural components for pressurized tanks

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    Process of fabricating stiffened section components of pressurized tanks for aerospace use was developed. A potential use of the fabrication process is the production of gore and quarter-panel sections of hydrogen and oxygen tanks for space vehicle boosters

    Rethinking rehabilitation: socio-ecology of tanks and water harvesting in Rajasthan, North-west India

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    In the arid and semi- arid Indian state of Rajasthan, tanks and ponds have been a mainstay of rural communities for centuries. There are over 4600 large minor irrigation tanks, plus numerous johads, bandhs and pals (small water harvesting structures). This paper assesses a strategy proposed for rehabilitating 1200 of the larger tanks. It argues that treating tanks only as flow irrigation systems—which lies at the center of the mainstream thinking on rehabilitating surface irrigation systems is very likely to result in a flawed strategy when applied to tanks. Instead, reviewing the successful experience of NGOs like PRADAN and Tarun Bharat Sangh in reviving and rehabilitating clusters of small traditional water harvesting structures at a watershed level, it posits that Rajasthan's tanks belong more to the watershed development domain than to the irrigation domain and that a strategy that views tanks as multi-use socio-ecological constructs, and which recognizes varied stakeholder groups is more likely to enhance the social value of tanks.

    Special tool seals conductors with combination of plastic sleeves

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    Special tool seals electrical conductors connecting instrumentation within space vehicle cryogenic fuel tanks and oxidizer tanks. An inner sleeve of fluorinated ethylene-propylene and an outer sleeve of tetrafluoroethylene enclose a bundle of conductors and are heated with the tool to form a tight seal of the bundle and each individual wire

    An Economic Analysis of Tank Rehabilitation in Madurai District of Tamil Nadu

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    There has been a growing realization for rehabilitation and restoration of irrigation tanks with farmers’ participation. The study has presented the costs and benefits of tank rehabilitation and financial feasibility of investment in tank rehabilitation. The total annual income has been found higher in the rehabilitated tanks than the non-rehabilitated tanks and amongst the rehabilitated tanks, panchayat tanks with community well has depicted the highest annual income. The investment analysis has revealed the net present worth to be positive, the B-C ratio to be more than 1.5 and the internal rate of return to be more than the opportunity cost of capital. This shows that all the three investments in tank rehabilitation are economically viable. The study has suggested that rehabilitation work should be undertaken in all the non-rehabilitated tanks also. Besides, efforts should be made to provide supplemental irrigation to crops and to improve the PWD tank management regime.Agricultural and Food Policy,

    Gas Concentration Measurements in Underground Waste Storage Tanks

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    Currently over 100 underground tanks at the Hanford facility in eastern Washington state are being used to store high-level radioactive waste. With plans for a long-term nuclear-waste repository in Nevada in place (though not yet approved), one promising use for these underground storage tanks is as a temporary waystation for waste destined for the Nevada repository. However, without a reasonable understanding of the chemical reactions going on within the tanks, transporting waste in and out of the tanks has been deemed to be unsafe. One hazard associated with such storage mechanisms is explosion of flammable gases produced within the tank. Within many of the storage tanks is a sludge layer. This layer, which is a mixture of liquid and solids, contains most of the radioactive material. Radioactive decay and its associated heat can produce several flammable materials within this layer. Two components of particular concern are hydrogen (H2) and nitrous oxide (N2O), since they are highly volatile in the gaseous phase. Though the tanks have either forced or natural convection systems to vent these gases, the possibility of an explosion still exists. Measurements of these gases are taken in several ways. Continuous measurements are taken in the headspace, which is the layer between the tank ceiling and the liquid (supernatant) or sludge layer below. In tanks where a supernatant layer sits atop the sludge layer, there are often rollovers or gas release events (GREs), where a large chunk of sludge, after attaining a certain void fraction, becomes buoyant, rising through the supernatant and releasing its associated gas composition to the headspace. Such changes trigger a sensor, and thus measurements are also taken at that time. Lastly, a retained gas sample (RGS) can be taken from either the supernatant or sludge layer. Such a core sample is quite expensive, but can yield crucial data about the way gases are being produced in the sludge and convected through the supernatant. Unfortunately, the measurements from these three populations do not seem to match. In particular, the ratio r = [N2O]/[H2] varies from population to population. r also varies from tank to tank, but this can more readily be explained in terms of the waste composition of each tank. Since H2 is more volatile than N2O (and since there are more sources of oxygen in the headspace), lower values of r correspond to more hazardous situations. This variance in r is troubling, since we need to be able to explain why certain values of r are lower (and hence more dangerous) in certain areas of the tank. In this report we examine the data from three tanks. We first verify that the differences in r among populations is significant. We then postulate several mechanisms which could explain such a difference

    HAWC Upgrade for Multi-TeV {\gamma}-ray Detection

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    The High Altitude Water Cherenkov (HAWC) high-energy {\gamma}-ray observatory was completed in march 2015 in central Mexico. The detector, consisting of 300 water tanks, is currently being upgraded to improve its performance at Multi-TeV energies, with a sparse array of small water Cherenkov tanks. It will extend the instrumental area by a factor of 4, and enhance the sensitivity at the highest energies. In this contribution, the current status of the observatory is presented, as well as the coming upgrade. The electronics and the readout system for the new sparse array of small water tanks are also desrcibed, and results from simulations performed to optimize the performance of the array are discussed.Comment: Proceeding paper of a contribution at the 6th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2016) in Heidelberg, German

    Radiation analysis of various vehicle and payload configurations for the reusable nuclear shuttle

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    Radiation analyses were performed and shielding weight requirements were estimated for various candidate vehicle and payload configurations for use with the reusable nuclear shuttle. The analyses included both point kernel and Monte Carlo approaches. The effects on reduced shield weight were determined for propellant ranks with pointed conical tank bottoms and for one case of a cluster of small tanks. This later case, however, had an arrangement which had no center tank in the upper tier of tanks. This effect negated most of the gain of going to the smaller tanks. A range of shield weights is presented for various light and heavy manned payload configurations when used in conjunction with a single liquid hydrogen propellant tank, 33 ft in diameter with a 15 deg conical tank bottom
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