13,976 research outputs found

    A Simple Numerical Model for the Study of Baroclinic Estuarine Shelf Interactions

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    A one and a half layer nonlinear f-plane numerical model was used to study estuarine-shelf interactions. The single active layer covered a domain consisting of a 100 km long by 20 km wide channel discharging onto a 100 km wide by 300 km long shelf. Channel and western” shelf boundaries were no-slip, eastern or oceanic boundary was free-slip and northern and southern shelf boundaries were open. The channel was forced with a constant inflow velocity spun up from 2 cm s-1 to 27 cm s-1over five days. The model initial conditions were a flat interface at ten meters and zero velocity except at the inflow. Effects of varying interfacial friction, Newtonian cooling (vertical mixing of density or detrainment), channel configuration and wind stress were examined. The principal result was to show that Newtonian cooling rather than interfacial friction played key role in deceleration and stagnation of an intrusion on the shelf relative to the constant phase speed in the channel. Deceleration of the density intrusion along the shelf coast agreed with results of three-dimensional numerical models, some laboratory models and with certain observed features of the Chesapeake Bay plume, for example. Results of a three-dimensional model were qualitatively reproduced as were features of a model which explicitly allowed the density interface to surface; that is, the plume flow was anticyclonic and marked by a region of supercritical flow along its outer edge. There was an abrupt transition, marked by strong nonlinear dynamics, from the plume to a coastal jet. Effects of channel configuration agreed with results of other models. Effects of wind stress were not adequately modeled probably due to failure to resolve the Ekman layer

    Contingency power for small turboshaft engines using water injection into turbine cooling air

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    Because of one engine inoperative requirements, together with hot-gas reingestion and hot day, high altitude takeoff situations, power augmentation for multiengine rotorcraft has always been of critical interest. However, power augmentation using overtemperature at the turbine inlet will shorten turbine life unless a method of limiting thermal and mechanical stresses is found. A possible solution involves allowing the turbine inlet temperature to rise to augment power while injecting water into the turbine cooling air to limit hot-section metal temperatures. An experimental water injection device was installed in an engine and successfully tested. Although concern for unprotected subcomponents in the engine hot section prevented demonstration of the technique's maximum potential, it was still possible to demonstrate increases in power while maintaining nearly constant turbine rotor blade temperature

    Open charm yields in d+Au collisions at sqrt[sNN]=200 GeV

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    Midrapidity open charm spectra from direct reconstruction of D0(D0-bar)-->K± pi ± in d+Au collisions and indirect electron-positron measurements via charm semileptonic decays in p+p and d+Au collisions at sqrt[sNN]=200 GeV are reported. The D0(D0-bar) spectrum covers a transverse momentum (pT) range of 0.1<pT<3 GeV/c, whereas the electron spectra cover a range of 1<pT<4 GeV/c. The electron spectra show approximate binary collision scaling between p+p and d+Au collisions. From these two independent analyses, the differential cross section per nucleon-nucleon binary interaction at midrapidity for open charm production from d+Au collisions at BNL RHIC is d sigma NNcc-bar/dy=0.30±0.04(stat)±0.09(syst) mb. The results are compared to theoretical calculations. Implications for charmonium results in A+A collisions are discussed

    Measurements of transverse energy distributions in Au+Au collisions at sqrt [sNN ]=200 GeV

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    Transverse energy ( ET ) distributions have been measured for Au+Au collisions at sqrt[sNN ]=200 GeV by the STAR Collaboration at RHIC. ET is constructed from its hadronic and electromagnetic components, which have been measured separately. ET production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of ET per charged particle agrees well with measurements at lower collision energy, indicating that the growth in ET for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total ET is consistent with a final state dominated by mesons and independent of centrality

    Pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at sqrt[sNN ]=200 GeV

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    The pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at sqrt[sNN ]=200 GeV are presented. The charged particle density at midrapidity, its pseudorapidity asymmetry, and centrality dependence are reasonably reproduced by a multiphase transport model, by HIJING, and by the latest calculations in a saturation model. Ratios of transverse momentum spectra between backward and forward pseudorapidity are above unity for pT below 5 GeV/c . The ratio of central to peripheral spectra in d+Au collisions shows enhancement at 2< pT <6 GeV/c , with a larger effect at backward rapidity than forward rapidity. Our measurements are in qualitative agreement with gluon saturation and in contrast to calculations based on incoherent multiple partonic scatterings

    Azimuthal anisotropy in Au+Au collisions at SNN=200GeV

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    The results from the STAR Collaboration on directed flow (v1), elliptic flow (v2), and the fourth harmonic (v4) in the anisotropic azimuthal distribution of particles from Au+Au collisions at sqrt[sNN]=200GeV are summarized and compared with results from other experiments and theoretical models. Results for identified particles are presented and fit with a blast-wave model. Different anisotropic flow analysis methods are compared and nonflow effects are extracted from the data. For v2, scaling with the number of constituent quarks and parton coalescence are discussed. For v4, scaling with v22 and quark coalescence are discussed

    Transverse-momentum dependent modification of dynamic texture in central Au+Au collisions at sqrt[sNN]=200GeV

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    Correlations in the hadron distributions produced in relativistic Au+Au collisions are studied in the discrete wavelet expansion method. The analysis is performed in the space of pseudorapidity (| eta | <= 1) and azimuth(full 2 pi ) in bins of transverse momentum (pt) from 0.14 <= pt <= 2.1GeV/c. In peripheral Au+Au collisions a correlation structure ascribed to minijet fragmentation is observed. It evolves with collision centrality and pt in a way not seen before, which suggests strong dissipation of minijet fragmentation in the longitudinally expanding medium.Alle Autoren: J. Adams, M. M. Aggarwal, Z. Ahammed, J. Amonett, B. D. Anderson, D. Arkhipkin, G. S. Averichev, S. K. Badyal, Y. Bai, J. Balewski, O. Barannikova, L. S. Barnby, J. Baudot, S. Bekele, V. V. Belaga, R. Bellwied, J. Berger, B. I. Bezverkhny, S. Bharadwaj, A. Bhasin, A. K. Bhati, V. S. Bhatia, H. Bichsel, A. Billmeier, L. C. Bland, C. O. Blyth, B. E. Bonner, M. Botje, A. Boucham, A. Brandin, A. Bravar, M. Bystersky, R. V. Cadman, X. Z. Cai, H. Caines, M. Calderón de la Barca Sánchez, J. Castillo, D. Cebra, Z. Chajecki, P. Chaloupka, S. Chattopdhyay, H. F. Chen, Y. Chen, J. Cheng, M. Cherney, A. Chikanian, W. Christie, J. P. Coffin, T. M. Cormier, J. G. Cramer, H. J. Crawford, D. Das, S. Das, M. M. de Moura, A. A. Derevschikov, L. Didenko, T. Dietel, S. M. Dogra, W. J. Dong, X. Dong, J. E. Draper, F. Du, A. K. Dubey, V. B. Dunin, J. C. Dunlop, M. R. Dutta Mazumdar, V. Eckardt, W. R. Edwards, L. G. Efimov, V. Emelianov, J. Engelage, G. Eppley, B. Erazmus, M. Estienne, P. Fachini, J. Faivre, R. Fatemi, J. Fedorisin, K. Filimonov, P. Filip, E. Finch, V. Fine, Y. Fisyak, K. Fomenko, J. Fu, C. A. Gagliardi, J. Gans, M. S. Ganti, L. Gaudichet, F. Geurts, V. Ghazikhanian, P. Ghosh, J. E. Gonzalez, O. Grachov, O. Grebenyuk, D. Grosnick, S. M. Guertin, Y. Guo, A. Gupta, T. D. Gutierrez, T. J. Hallman, A. Hamed, D. Hardtke, J. W. Harris, M. Heinz, T. W. Henry, S. Hepplemann, B. Hippolyte, A. Hirsch, E. Hjort, G. W. Hoffmann, H. Z. Huang, S. L. Huang, E. W. Hughes, T. J. Humanic, G. Igo, A. Ishihara, P. Jacobs, W. W. Jacobs, M. Janik, H. Jiang, P. G. Jones, E. G. Judd, S. Kabana, K. Kang, M. Kaplan, D. Keane, V. Yu. Khodyrev, J. Kiryluk, A. Kisiel, E. M. Kislov, J. Klay, S. R. Klein, A. Klyachko, D. D. Koetke, T. Kollegger, M. Kopytine, L. Kotchenda, M. Kramer, P. Kravtsov, V. I. Kravtsov, K. Krueger, C. Kuhn, A. I. Kulikov, A. Kumar, R. Kh. Kutuev, A. A. Kuznetsov, M. A. C. Lamont, J. M. Landgraf, S. Lange, F. Laue, J. Lauret, A. Lebedev, R. Lednicky, S. Lehocka, M. J. LeVine, C. Li, Q. Li, Y. Li, G. Lin, S. J. Lindenbaum, M. A. Lisa, F. Liu, L. Liu, Q. J. Liu, Z. Liu, T. Ljubicic, W. J. Llope, H. Long, R. S. Longacre, M. Lopez-Noriega, W. A. Love, Y. Lu, T. Ludlam, D. Lynn, G. L. Ma, J. G. Ma, Y. G. Ma, D. Magestro, S. Mahajan, D. P. Mahapatra, R. Majka, L. K. Mangotra, R. Manweiler, S. Margetis, C. Markert, L. Martin, J. N. Marx, H. S. Matis, Yu. A. Matulenko, C. J. McClain, T. S. McShane, F. Meissner, Yu. Melnick, A. Meschanin, M. L. Miller, N. G. Minaev, C. Mironov, A. Mischke, D. K. Mishra, J. Mitchell, B. Mohanty, L. Molnar, C. F. Moore, D. A. Morozov, M. G. Munhoz, B. K. Nandi, S. K. Nayak, T. K. Nayak, J. M. Nelson, P. K. Netrakanti, V. A. Nikitin, L. V. Nogach, S. B. Nurushev, G. Odyniec, A. Ogawa, V. Okorokov, M. Oldenburg, D. Olson, S. K. Pal, Y. Panebratsev, S. Y. Panitkin, A. I. Pavlinov, T. Pawlak, T. Peitzmann, V. Perevoztchikov, C. Perkins, W. Peryt, V. A. Petrov, S. C. Phatak, R. Picha, M. Planinic, J. Pluta, N. Porile, J. Porter, A. M. Poskanzer, M. Potekhin, E. Potrebenikova, B. V. K. S. Potukuchi, D. Prindle, C. Pruneau, J. Putschke, G. Rakness, R. Raniwala, S. Raniwala, O. Ravel, R. L. Ray, S. V. Razin, D. Reichhold, J. G. Reid, G. Renault, F. Retiere, A. Ridiger, H. G. Ritter, J. B. Roberts, O. V. Rogachevskiy, J. L. Romero, A. Rose, C. Roy, L. Ruan, R. Sahoo, I. Sakrejda, S. Salur, J. Sandweiss, I. Savin, P. S. Sazhin, J. Schambach, R. P. Scharenberg, N. Schmitz, K. Schweda, J. Seger, P. Seyboth, E. Shahaliev, M. Shao, W. Shao, M. Sharma, W. Q. Shen, K. E. Shestermanov, S. S. Shimanskiy, E. Sichtermann, F. Simon, R. N. Singaraju, G. Skoro, N. Smirnov, R. Snellings, G. Sood, P. Sorensen, J. Sowinski, J. Speltz, H. M. Spinka, B. Srivastava, A. Stadnik, T. D. S. Stanislaus, R. Stock, A. Stolpovsky, M. Strikhanov, B. Stringfellow, A. A. P. Suaide, E. Sugarbaker, C. Suire, M. Sumbera, B. Surrow, T. J. M. Symons, A. Szanto de Toledo, P. Szarwas, A. Tai, J. Takahashi, A. H. Tang, T. Tarnowsky, D. Thein, J. H. Thomas, S. Timoshenko, M. Tokarev, T. A. Trainor, S. Trentalange, R. E. Tribble, O. D. Tsai, J. Ulery, T. Ullrich, D. G. Underwood, A. Urkinbaev, G. Van Buren, M. van Leeuwen, A. M. Vander Molen, R. Varma, I. M. Vasilevski, A. N. Vasiliev, R. Vernet, S. E. Vigdor, Y. P. Viyogi, S. Vokal, S. A. Voloshin, M. Vznuzdaev, W. T. Waggoner, F. Wang, G. Wang, G. Wang, X. L. Wang, Y. Wang, Y. Wang, Z. M. Wang, H. Ward, J. W. Watson, J. C. Webb, R. Wells, G. D. Westfall, A. Wetzler, C. Whitten Jr., H. Wieman, S. W. Wissink, R. Witt, J. Wood, J. Wu, N. Xu, Z. Xu, Z. Z. Xu, E. Yamamoto, P. Yepes, V. I. Yurevich, Y. V. Zanevsky, H. Zhang, W. M. Zhang, Z. P. Zhang, P. A. Zolnierczuk, R. Zoulkarneev, Y. Zoulkarneeva, and A. N. Zubare
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