267 research outputs found

    Thermal Management Design for the X-33 Lifting Body

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    The X-33 Advantage Technology Demonstrator offers a rare and exciting opportunity in Thermal Protection System development. The experimental program incorporates the latest design innovation in re-useable, low life cycle cost, and highly dependable Thermal Protection materials and constructions into both ground based and flight test vehicle validations. The unique attributes of the X-33 demonstrator for design application validation for the full scale Reusable Launch Vehicle, (RLV), are represented by both the configuration of the stand-off aeroshell, and the extreme exposures of sub-orbital hypersonic re-entry simulation. There are several challenges of producing a sub-orbital prototype demonstrator of Single Stage to Orbit/Reusable Launch Vehicle (SSTO/RLV) operations. An aggressive schedule with budgetary constraints precludes the opportunity for an extensive verification and qualification program of vehicle flight hardware. However, taking advantage of off the shelf components with proven technologies reduces some of the requirements for additional testing. The effects of scale on thermal heating rates must also be taken into account during trajectory design and analysis. Described in this document are the unique Thermal Protection System (TPS) design opportunities that are available with the lifting body configuration of the X-33. The two principal objectives for the TPS are to shield the primary airframe structure from excessive thermal loads and to provide an aerodynamic mold line surface. With the relatively benign aeroheating capability of the lifting body, an integrated stand-off aeroshell design with minimal weight and reduced procurement and operational costs is allowed. This paper summarizes the design objectives of the X-33 TPS, the flight test requirements driven configuration, and design benefits. Comparisons are made of the X-33 flight profiles and Space Shuttle Orbiter, and lifting body Reusable Launch Vehicle aerothermal environments. The X-33 TPS is based on a design to cost configuration concept. Only RLV critical technologies are verified to conform to cost and schedule restrictions. The one-off prototype vehicle configuration has evolved to minimize the tooling costs by reducing the number of unique components. Low cost approaches such as a composite/blanket leeward aeroshell and the use of Shuttle technology are implemented where applicable. The success of the X-33 will overcome the ballistic re-entry TPS mindset. The X-33 TPS is tailored to an aircraft type mission while maintaining sufficient operational margins. The flight test program for the X-33 will demonstrate that TPS for the RLV is not simply a surface insulation but rather an integrated aeroshell system

    Comparison of Mechanical, Assisted and Manual Harvest of Origanum vulgare L.

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    In Italy, the production of Origanum vulgare L. is lower than the national market demand, so there is an increasing interest in this crop, even if the manual harvest and bunch binding represent ca. 60% of the production cost. The aim of this work is to evaluate the harvest efficiency, as well as the working capacity, productivity and quality of mechanical harvesting by means of a reaper-binder designed for cereal and forage crops and assisted harvesting by means of a long-reach edge trimmer. In fact, the final aim is to suggest a machine and a method for oregano harvesting that could significantly reduce the time and, therefore, the cost of this crop operation, while achieving a product quality similar to that obtained by manual harvesting. Tests of mechanical and assisted harvesting were carried out using a reaper-binder after modifying it (i.e., reducing its forward speed, cutting height and bunch size to improve its working capacity, productivity and quality) and an edge trimmer, respectively. The tests of mechanical and assisted harvesting were compared with manual harvesting. In the testing field, with an irregular shape and an area of one hectare, nine rows were selected and divided into three replications, each comprising three tests, i.e., mechanical, assisted and manual harvesting. The modified reaper-binder allowed us to achieve working capacity and productivity rates much higher than those obtained with manual harvesting. Moreover, its harvest quality, in terms of bunch weight and binding height, favourably compares with that manually obtained. Furthermore, the edge trimmer allowed us to achieve working capacity and productivity rates lower than those obtained by means of the reaper-binder but much higher than in manual harvesting. Thus, the reaper-binder can minimise the harvest time and, therefore, cost while harvesting bunches slightly bigger than those manually harvested, even if it requires a high initial investment cost. Instead, the edge trimmer can be a cheap solution for reducing the harvest time and cost. Therefore, mechanical and assisted harvesting could spread oregano production in areas of inland Sicily and other Mediterranean regions that are often cultivated with low-profit herbaceous plant species or lie fallow. Thus, it would be possible to increase farmers’ incomes and job opportunities, as well as preventing or minimising the hydrogeological instability in these areas

    Potential production of biogas from prinkly pear (opuntia ficus-indica L.) in sicilian uncultivated areas

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    The aim of this work is to evaluate the potential production of biogas and, indirectly, biomethane or electric and thermal energy, from prinkly pear (Opuntia ficus-indica L.), to be grown in a part of Sicilian uncultivated areas and co-digested together with the available livestock manure and slurry. In order to increase the Renewable Energy Sources (RES) and reduce the dependency from fossil ones, the conversion of biomass into biogas through Anaerobic Digestion (AD) process is paramount for producing biomethane, to be used as fuel for means of transport and agricultural machines or heating, or electric and thermal energy through Combined Heat and Power (CHP) plants. Moreover, the digestate produced through AD process can be applied to soils as organic fertiliser in the place of chemical ones. Prinkly pear was supposed to be grown, by mechanising the harvest of cladods (modified stems), in a part of the Sicilian Used Agricultural Area that is currently uncultivated (totally 600, 000 ha ca.), identified by means of a GIS software. Thus it was possible to compute the potential production of biogas and, indirectly, biomethane or electric and thermal energy. The results show that the Sicilian potential production of biogas is 612, 115 103m3, from which 342, 784 103m3of biomethane could be extracted or 67, 038 MWh of electric energy and 70, 390 MWh MWh of thermal energy could be generated. Moreover the obtained digestate would be used as biofertiliser, within both conventional and organic farming. This work demonstrates that the production of RES, such as biogas from prinkly pear, represents a very profitable way of using the uncultivated areas: the income of the farmer would include not only that deriving from the sale of biomethane or electric and thermal energy but also the saving for replacing chemical fertilisers with digestate and the subsidy for producing biomethane as fuel for means of transport or electric and thermal energy from biogas

    Sicilian potential biogas production from Citrus industry by-product

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    In Europe, Italy is the second nation after Spain in Citrus production and 49% ca. of national fruit production is located in Sicily. The by-product obtained from the industrial processing of Citrus fruits into juice and essential oils is called \u201cpastazzo\u201d or Citrus Waste (CW). This study is aimed at evaluating the Sicilian potential biogas and energy production from the above \u201cpastazzo\u201d and verifying the possibility of using this by-product for Anaerobic Digestion (AD) process within 30 km from processing plants. The areas cultivated with Citrus species in Sicily and their distribution in the various municipal districts were mapped and analysed by means of QGIS software, together with the main Citrus processing plants and the three existing AD plants. The statistical data about the amounts of the by-product of Citrus processing industry were evaluated, in order to compute the Sicilian potential biogas and energy production. In Sicily it is possible to obtain, through the use of \u201cpastazzo\u201d, a yearly production of 12,916,800 m3 ca. of biogas, equal to 24,250,930 kWh of electric energy and 25,463,477 kWh of thermal energy or 6,200,064 m3 of biomethane. This high potential biogas and energy production is not be currently used in a sustainable way from the energetic and economic points of view, because the existing AD plants are farer than 30 km from Citrus processing plants. The CW produced in Sicily could be used inside a bio-reactor, together with other raw materials (e.g. pomace and wastewater from olive oil mills, cereal straw, poultry manure and Italian sainfoin or Hedysarum coronarium), for AD process

    Coarse Grained Density Functional Theories for Metallic Alloys: Generalized Coherent Potential Approximations and Charge Excess Functional Theory

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    The class of the Generalized Coherent Potential Approximations (GCPA) to the Density Functional Theory (DFT) is introduced within the Multiple Scattering Theory formalism for dealing with, ordered or disordered, metallic alloys. All GCPA theories are based on a common ansatz for the kinetic part of the Hohenberg-Kohn functional and each theory of the class is specified by an external model concerning the potential reconstruction. The GCPA density functional consists of marginally coupled local contributions, does not depend on the details of the charge density and can be exactly rewritten as a function of the appropriate charge multipole moments associated with each lattice site. A general procedure based on the integration of the 'qV' laws is described that allows for the explicit construction the same function. The coarse grained nature of the GCPA density functional implies great computational advantages and is connected with the O(N) scalability of GCPA algorithms. Moreover, it is shown that a convenient truncated series expansion of the GCPA functional leads to the Charge Excess Functional (CEF) theory [E. Bruno, L. Zingales and Y. Wang, Phys. Rev. Lett. {\bf 91}, 166401 (2003)] which here is offered in a generalized version that includes multipolar interactions. CEF and the GCPA numerical results are compared with status of art LAPW full-potential density functional calculations for 62, bcc- and fcc-based, ordered CuZn alloys, in all the range of concentrations. These extensive tests show that the discrepancies between GCPA and CEF are always within the numerical accuracy of the calculations, both for the site charges and the total energies. Furthermore, GCPA and CEF very carefully reproduce the LAPW site charges and the total energy trends.Comment: 19 pages, 11 figure

    P10-04. Mechanisms of HIV-1 detection by plasmacytoid dendritic cells

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    Images of an equatorial outflow in SS433

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    We have imaged the X-ray binary SS433 with unprecedented Fourier-plane coverage at 6cm using simultaneously the VLBA, MERLIN, and the VLA, and also at 20cm with the VLBA. At both wavelengths we have securely detected smooth, low-surface brightness emission having the appearance of a `ruff' or collar attached perpendicularly to the well-studied knotty jets in this system, extending over at least a few hundred AU. We interpret this smooth emission as a wind-like outflow from the binary, and discuss its implications for the present evolutionary stage of this system.Comment: Accepted by ApJ Letter

    Improvement of Fresh Ovine “Tuma” Cheese Quality Characteristics by Application of Oregano Essential Oils

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    In the present work, oregano essential oils (OEOs) were applied to process the fresh ovine cheese "Tuma" obtained by pressed cheese technology. Cheese making trials were performed under industrial conditions using ewe's pasteurized milk and two strains of Lactococcus lactis (NT1 and NT5) as fermenting agents. Two experimental cheese products (ECP) were obtained through the addition of 100 (ECP100) and 200 (ECP200) & mu;L/L of OEO to milk, while the control cheese product (CCP) was OEO-free. Both Lc. lactis strains showed in vitro and in vivo ability to grow in the presence of OEOs and to dominate over indigenous milk lactic acid bacteria (LAB) resistant to pasteurization. In the presence of OEOs, the most abundant compound found in cheese was carvacrol, constituting more than 65% of the volatile fraction in both experimental products. The addition of OEOs did not influence ash, fat, or protein content, but it increased by 43% the antioxidant capacity of the experimental cheeses. ECP100 cheeses showed the best appreciation scores by the sensory panel. In order to investigate the ability OEOs to be used as a natural preservative, a test of artificial contamination was carried out, and the results showed a significant reduction of the main dairy pathogens in OEO-added cheeses

    Gag Mutations Strongly Contribute to HIV-1 Resistance to Protease Inhibitors in Highly Drug-Experienced Patients besides Compensating for Fitness Loss

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    Human immunodeficiency virus type 1 (HIV-1) resistance to protease inhibitors (PI) results from mutations in the viral protease (PR) that reduce PI binding but also decrease viral replicative capacity (RC). Additional mutations compensating for the RC loss subsequently accumulate within PR and in Gag substrate cleavage sites. We examined the respective contribution of mutations in PR and Gag to PI resistance and RC and their interdependence using a panel of HIV-1 molecular clones carrying different sequences from six patients who had failed multiple lines of treatment. Mutations in Gag strongly and directly contributed to PI resistance besides compensating for fitness loss. This effect was essentially carried by the C-terminal region of Gag (containing NC-SP2-p6) with little or no contribution from MA, CA, and SP1. The effect of Gag on resistance depended on the presence of cleavage site mutations A431V or I437V in NC-SP2-p6 and correlated with processing of the NC/SP2 cleavage site. By contrast, reverting the A431V or I437V mutation in these highly evolved sequences had little effect on RC. Mutations in the NC-SP2-p6 region of Gag can be dually selected as compensatory and as direct PI resistance mutations, with cleavage at the NC-SP2 site behaving as a rate-limiting step in PI resistance. Further compensatory mutations render viral RC independent of the A431V or I437V mutations while their effect on resistance persists
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