131 research outputs found

    A model for closing the inviscid form of the average-passage equation system

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    A mathematical model is proposed for closing or mathematically completing the system of equations which describes the time average flow field through the blade passages of multistage turbomachinery. These equations referred to as the average passage equation system govern a conceptual model which has proven useful in turbomachinery aerodynamic design and analysis. The closure model is developed so as to insure a consistency between these equations and the axisymmetric through flow equations. The closure model was incorporated into a computer code for use in simulating the flow field about a high speed counter rotating propeller and a high speed fan stage. Results from these simulations are presented

    A numerical simulation of the inviscid flow through a counter-rotating propeller

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    The results of a numerical simulation of the time-averaged inviscid flow field through the blade rows of a multiblade row turboprop configuration are presented. The governing equations are outlined along with a discussion of the solution procedure and coding strategy. Numerical results obtained from a simulation of the flow field through a modern high-speed turboprop will be shown

    Utilization of parallel processing in solving the inviscid form of the average-passage equation system for multistage turbomachinery

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    A procedure is outlined which utilizes parallel processing to solve the inviscid form of the average-passage equation system for multistage turbomachinery along with a description of its implementation in a FORTRAN computer code, MSTAGE. A scheme to reduce the central memory requirements of the program is also detailed. Both the multitasking and I/O routines referred to are specific to the Cray X-MP line of computers and its associated SSD (Solid-State Disk). Results are presented for a simulation of a two-stage rocket engine fuel pump turbine

    Modulatory antimicrobial activity of Piper arboretum extracts (Zingiberaceae)

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    The side effects of certain antibiotics have been a recent dilemma in the medical arena. Due this fact, the necessity of natural product discovery could provide important indications against several pharmacological targets and combat many infectious agents. Piper arboreum Aub. (Piperaceae) has been used by Brazilian traditional communities against several illnesses including rheumatism, bronchitis, sexually transmitted diseases and complaints of the urinary tract. Medicinal plants are a source of several remedies used in clinical practice to combat microbial infections. In this study, ethanol extract and fractions of Piper arboreum leaves were used to assay antimicrobial and modulatory activity. The minimum inhibitory concentration (MIC) was determined using microdilution method of ethanol extract and fractions from the leaves of P. arboreum ranging between 8 and 1024 mgmL–1. The capacity of these natural products to enhance the activity of antibiotic and antifungal drugs was also assayed. In these tests, natural products were combined with drugs. The natural products assayed did not demonstrate any clinically relevant antimicrobial activity (MIC ³ 1024 mg mL–1). However, the modulation of antibiotic activity assay observed a synergistic activity of natural products combined with antifungal (such as nystatin and amphotericin B) and antibiotic drugs (such as amikacin, gentamicin and kanamycin). According to these results, these natural products can be an interesting alternative not only to combat infectious diseases caused by bacteria or fungi, but also to combat enhanced resistance of microorganisms to antibiotic and antifungal drugs

    Measurement of the CKM angle Îł from a combination of B±→Dh± analyses

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    A combination of three LHCb measurements of the CKM angle Îł is presented. The decays B±→D K± and B±→Dπ± are used, where D denotes an admixture of D0 and D0 mesons, decaying into K+K−, π+π−, K±π∓, K±π∓π±π∓, K0Sπ+π−, or K0S K+K− ïŹnal states. All measurements use a dataset corresponding to 1.0 fb−1 of integrated luminosity. Combining results from B±→D K± decays alone a best-ïŹt value of Îł =72.0◩ is found, and conïŹdence intervals are set Îł ∈ [56.4,86.7]◩ at 68% CL, Îł ∈ [42.6,99.6]◩ at 95% CL. The best-ïŹt value of Îł found from a combination of results from B±→Dπ± decays alone, is Îł =18.9◩, and the conïŹdence intervals Îł ∈ [7.4,99.2]◩ âˆȘ [167.9,176.4]◩ at 68% CL are set, without constraint at 95% CL. The combination of results from B± → D K± and B± → Dπ± decays gives a best-ïŹt value of Îł =72.6◩ and the conïŹdence intervals Îł ∈ [55.4,82.3]◩ at 68% CL, Îł ∈ [40.2,92.7]◩ at 95% CL are set. All values are expressed modulo 180◩, and are obtained taking into account the effect of D0–D0 mixing

    Identification of a resistance gene Rpi-dlc1 to Phytophthora infestans in European accessions of Solanum dulcamara

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    Initial screening of 14 Solanum dulcamara accessions enabled the identification of individuals resistant and susceptible to Phytophthora infestans. Crosses between contrasting genotypes resulted in three F2–BC1 populations segregating for resistance to late blight in a laboratory assay and under field conditions. Genetic profiling of one of these populations using 128 AFLP primers generated three markers linked to the resistant phenotype. Blast analysis of the sequenced markers resulted in a plausible gene position on the distal end of the long arm of chromosome 9 that could be confirmed by CAPS markers. Thus, we describe a first resistant gene, named Rpi-dlc1, from S. dulcamara, a Solanum species native to Europe. In addition, one population was tested for broadness of resistance responses using a set of seven additional P. infestans isolates, varying in virulence. This indicated the possible presence of additional Rpi genes

    Measurement of the flavour-specific CP-violating asymmetry as sl in B0s decays

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    The CP  -violating asymmetry is studied using semileptonic decays of and mesons produced in pp   collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fb−1. The reconstructed final states are , with the particle decaying in the ϕπ± mode. The yields are summed over and initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain , where the first uncertainty is statistical and the second systematic
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