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Sample records for atmospheric neutrino-induced cascades

  1. A Search For Atmospheric Neutrino-Induced Cascades with IceCube

    CERN Document Server

    D'Agostino, Michelangelo

    2009-01-01

    The IceCube detector is an all-flavor neutrino telescope. For several years IceCube has been detecting muon tracks from charged-current muon neutrino interactions in ice. However, IceCube has yet to observe the electromagnetic or hadronic particle showers or "cascades" initiated by charged or neutral-current neutrino interactions. The first detection of such an event signature will likely come from the known flux of atmospheric electron and muon neutrinos. A search for atmospheric neutrino-induced cascades was performed using a full year of IceCube data. Reconstruction and background rejection techniques were developed to reach, for the first time, an expected signal-to-background ratio ~1 or better.

  2. First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector

    Science.gov (United States)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brown, A. M.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lehmann, R.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schoenwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.

    2011-10-01

    We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007-2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of 8.3±3.6. At 90% confidence we set an upper limit of E2Φ90%CLE-2 and the flavor composition of the νe∶νμ∶ντ flux is 1∶1∶1 at the Earth. The atmospheric neutrino analysis was optimized for lower energies. A total of 12 events were observed with energies above 5 TeV. The observed number of events is consistent with the expected background, within the uncertainties.

  3. First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector

    CERN Document Server

    Abbasi, R; Abu-Zayyad, T; Adams, J; Aguilar, J A; Ahlers, M; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Bay, R; Alba, J L Bazo; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K -H; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; B, S; "oser,; Botner, O; Braun, J; Brown, A M; Buitink, S; Carson, M; Chirkin, D; Christy, B; Clem, J; Clevermann, F; Cohen, S; Colnard, C; Cowen, D F; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Demir, L; "ors,; Denger, T; Depaepe, O; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; D'iaz-Vélez, J C; Dierckxsens, M; Dreyer, J; Dumm, J P; Ehrlich, R; Eisch, J; Ellsworth, R W; aard, O Engdeg; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Foerster, M M; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Geisler, M; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Grant, D; Griesel, T; Gross, A; Grullon, S; Gurtner, M; Ha, C; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heinen, D; Helbing, K; Herquet, P; Hickford, S; Hill, G C; Hoffman, K D; Homeier, A; Hoshina, K; Hubert, D; Huelsnitz, W; Hül\\ss, J -P; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Joseph, J M; Kampert, K -H; Kappes, A; Karg, T; Karle, A; Kelley, J L; Kenny, P; Kiryluk, J; Kislat, F; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Kowarik, T; Krasberg, M; Krings, T; Kroll, G; Kuehn, K; Kuwabara, T; Labare, M; Lafebre, S; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lünemann, J; Madsen, J; Majumdar, P; Marotta, A; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Nie\\ssen, P; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Ono, M; Panknin, S; Paul, L; Heros, C Pérez de los; Petrovic, J; Piegsa, A; Pieloth, D; Porrata, R; Posselt, J; Price, P B; Prikockis, M; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Rodrigues, J P; Roth, P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Schmidt, T; Schoenwald, A; Schukraft, A; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Slipak, A; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stephens, G; Stezelberger, T; Stokstad, R G; Stoyanov, S; Strahler, E A; Straszheim, T; Stür, M; Sullivan, G W; Swillens, Q; Taavola, H; Taboada, I; Tamburro, A; Tarasova, O; Tepe, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; Tur\\v\\can, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Voigt, B; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Woschnagg, K; Xu, C; Xu, X W; Yodh, G; Yoshida, S; Zarzhitsky, P

    2011-01-01

    We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007-2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of $8.3\\pm 3.6$. At 90% confidence we set an upper limit of $E^2\\Phi_{90%CL}<3.6\\times10^{-7} GeV \\cdot cm^{-2} \\cdot s^{-1}\\cdot sr^{-1} $ on the diffuse flux of neutrinos of all flavors in the energy range between 24 TeV and 6.6 PeV assuming that $\\Phi \\propto E^{-2}$ and that the flavor composition of the $\

  4. First Evidence For Atmospheric Neutrino-Induced Cascades with the IceCube Detector

    CERN Document Server

    D'Agostino, Michelangelo

    2009-01-01

    IceCube is an all-flavor, cubic kilometer neutrino telescope currently under construction in the deep glacial ice at the South Pole. Its embedded optical sensors detect Cherenkov light from charged particles produced in neutrino interactions in the ice. For several years IceCube has been detecting muon tracks from charged-current muon neutrino interactions. However, IceCube has yet to observe the electromagnetic or hadronic particle showers or "cascades" initiated by charged-current or neutral-current neutrino interactions. The first detection of such an event signature is expected to come from the known flux of atmospheric electron and muon neutrinos. A search for atmospheric neutrino-induced cascades was performed using 275.46 days of data from IceCube's 22-string configuration. Reconstruction and background rejection techniques were developed to reach, for the first time, a signal-to-background ratio ~1. Above a reconstructed energy of 5 TeV, 12 candidate events were observed in the full dataset. The signa...

  5. Search for neutrino-induced cascade events in the icecube detector

    Energy Technology Data Exchange (ETDEWEB)

    Panknin, Sebastian

    2011-09-15

    This thesis presents results of a search for a diffuse flux of high energetic neutrinos from extra-terrestrial origin. Such a flux is predicted by several models of sources of cosmic ray particles. In a neutrino detector, such as IceCube, there are mainly two signatures available for detection of neutrinos: The track-like light signal of a neutrino induced muon and the spherical light pattern of a neutrino induced particle shower, called cascades in this context. The search is based on the measurement of neutrino induced cascades within the IceCube neutrino detector. The data were taken in 2008/2009 with a total uptime of 367 days. At that time the detector was still under construction and had just reached half of its final size. A search for a neutrino flux using cascades is sensitive to all neutrino flavors. A cascade develops within few meters, in contrast to the muon track of several kilometers length. Therefore a good energy reconstruction is possible. With such a reconstruction the astrophysical neutrino flux can be statistically distinguished from the background of atmospheric neutrinos. In the simulation of cascades so far it was not included, that in hadronic cascades muons are produced. This can influence the shape of the cascade, to a less spherical one. Therefore the effect was parameterized in this thesis and included in the simulation. Further cuts on the event topology and reconstructed energy were developed, in order to reduce the background of atmospheric muons and atmospheric neutrinos. Four events from the measured data pass these cuts. Taking the high systematic uncertainties into account, this result is in agreement with the expected background of 0.72{+-}0.28{+-}{sup 1.54}{sub 0.49} events. For an assumed flavor ratio of {nu}{sub e}:{nu}{sub {mu}}:{nu}{sub {tau}}=1:1:1 the upper limit for the all flavor neutrino flux is 9.5.10{sup -8}E{sup -2} GeVs{sup -1}sr{sup -1}cm{sup -2}.

  6. Atmospheric Neutrino Induced Muons in the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Aftabur Dipu [Univ. of Minnesota, Minneapolis, MN (United States)

    2007-02-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment. The MINOS Far Detector, located in the Soudan Underground Laboratory in Soudan MN, has been collecting data since August 2003. The scope of this dissertation involves identifying the atmospheric neutrino induced muons that are created by the neutrinos interacting with the rock surrounding the detector cavern, performing a neutrino oscillation search by measuring the oscillation parameter values of Δm$2\\atop{23}$ and sin223, and searching for CPT violation by measuring the charge ratio for the atmospheric neutrino induced muons. A series of selection cuts are applied to the data set in order to extract the neutrino induced muons. As a result, a total of 148 candidate events are selected. The oscillation search is performed by measuring the low to high muon momentum ratio in the data sample and comparing it to the same ratio in the Monte Carlo simulation in the absence of neutrino oscillation. The measured double ratios for the ''all events'' (A) and high resolution (HR) samples are RA = R$data\\atop{low/high}$/R$MC\\atop{low/high}$ = 0.60$+0.11\\atop{-0.10}$(stat) ± 0.08(syst) and RHR = R$data\\atop{low/high}$/R$MC\\atop{low/high}$ = 0.58$+0.14\\atop{-0.11}$(stat) ± 0.05(syst), respectively. Both event samples show a significant deviation from unity giving a strong indication of neutrino oscillation. A combined momentum and zenith angle oscillation fit is performed using the method of maximum log-likelihood with a grid search in the parameter space of Δm2 and sin2 2θ. The best fit point for both event samples occurs at Δm$2\\atop{23}$ = 1.3 x 10-3 eV2, and sin223 = 1. This result is compatible with previous measurements from the Super Kamiokande experiment and Soudan 2 experiments. The MINOS Far Detector is the first

  7. First search for extraterrestrial neutrino-induced cascades with IceCube

    CERN Document Server

    Kiryluk, J

    2009-01-01

    We report on the first search for extra-terrestrial neutrino-induced cascades in IceCube. The analyzed data were collected in the year 2007 when 22 detector strings were installed and operated. We will discuss the analysis methods used to reconstruct cascades and to suppress backgrounds. Simulated neutrino signal events with a E-2 energy spectrum, which pass the background rejection criteria, are reconstructed with a resolution dlogE ~ 0.27 in the energy range from ~20 TeV to a few PeV. We present the range of the diffuse flux of extra-terrestrial neutrinos in the cascade channel in IceCube within which we expect to be able to put a limit.

  8. First search for extraterrestrial neutrino-induced cascades with IceCube

    Energy Technology Data Exchange (ETDEWEB)

    IceCube Collaboration; Kiryluk, Joanna

    2009-05-22

    We report on the first search for extraterrestrial neutrino-induced cascades in IceCube.The analyzed data were collected in the year 2007 when 22 detector strings were installed and operated. We will discuss the analysis methods used to reconstruct cascades and to suppress backgrounds. Simulated neutrino signal events with a E-2 energy spectrum, which pass the background rejection criteria, are reconstructed with a resolution Delta(log E) ~;; 0.27 in the energy range from ~;; 20 TeV to a few PeV. We present the range of the diffuse flux of extra-terrestrial neutrinos in the cascade channel in IceCube within which we expect to be able to put a limit.

  9. Search for neutrino-induced cascades from gamma-ray bursts with AMANDA

    CERN Document Server

    Achterberg, A; Adams, J; Ahrens, J; Andeen, K; Auffenberg, J; Bahcall, J N; Bai, X; Baret, B; Barwick, S W; Bay, R; Beattie, K; Becka, T; Becker, J K; Becker, K H; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Blaufuss, E; Boersma, D J; Bohm, C; Bolmont, J; Boser, S; Botner, O; Bouchta, A; Braun, J; Burgess, C; Burgess, T; Castermans, T; Chirkin, D; Christy, B; Clem, J; Cowen, D F; D'Agostino, M V; Davour, A; Day, C T; De Clercq, C; Demirors, L; Descamps, F; Desiati, P; De Young, T; Díaz-Veléz, J C; Dreyer, J; Dumm, J P; Duvoort, M R; Edwards, W R; Ehrlich, R; Eisch, J; Ellsworth, R W; Evenson, P A; Fadiran, O; Fazely, A R; Filimonov, K; Foerster, M M; Fox, B D; Franckowiak, A; Gaisser, T K; Gallagher, J; Ganugapati, R; Geenen, H; Gerhardt, L; Goldschmidt, A; Goodman, J A; Gozzini, R; Griesel, T; Grullon, S; Gro, A; Gunasingha, R M; Gurtner, M; Hallgren, A; Halzen, F; Han, K; Hanson, K; Hardtke, D; Hardtke, R; Hart, J E; Hasegawa, Y; Hauschildt, T; Hays, D; Heise, J; Helbing, K; Hellwig, M; Herquet, P; Hill, G C; Hodges, J; Hoffman, K D; Hommez, B; Hoshina, K; Hubert, D; Hughey, B; Hulth, P O; Hultqvist, K; Hul, J P; Hundertmark, S; Inaba, M; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Jones, A; Joseph, J M; Kampert, K H; Karg, T; Karle, A; Kawai, H; Kelley, J L; Kitamura, N; Klein, S R; Klepser, S; Kohnen, G; Kolanoski, H; Köpke, L; Kowalski, M; Kowarik, T; Krasberg, M; Kühn, K; Labare, M; Landsman, H; Leich, H; Leier, D; Liubarsky, I; Lundberg, J; Lunemann, J; Madsen, J; Mase, K; Matis, H S; McCauley, T; McParland, C P; Meli, A; Messarius, T; Mészáros, P; Miyamoto, H; Mokhtarani, A; Montaruli, T; Morey, A; Morse, R; Movit, S M; Munich, K; Nahnhauer, R; Nam, J W; Nieen, P; Nygren, D R; Ogelman, H; Olivas, A; Patton, S; Peña-Garay, C; Pérez de los Heros, C; Piegsa, A; Pieloth, D; Pohl, A C; Porrata, R; Pretz, J; Price, P B; Przybylski, G T; Rawlins, K; Razzaque, S; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Robbins, S; Roth, P; Rott, C; Rutledge, D; Ryckbosch, D; Sander, H G; Sarkar, S; Schlenstedt, S; Schmidt, T; Schneider, D; Seckel, D; Semburg, B; Seo, S H; Seunarine, S; Silvestri, A; Smith, A J; Solarz, M; Song, C; Sopher, J E; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Steffen, P; Stezelberger, T; Stokstad, R G; Stoufer, M C; Stoyanov, S; Strahler, E A; Straszheim, T; Sulanke, K H; Sullivan, G W; Sumner, T J; Taboada, I; Tarasova, O; Tepe, A; Thollander, L; Tilav, S; Tluczykont, M; Toale, P A; Turcan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; Viscomi, V; Voigt, B; Wagner, W; Walck, C; Waldmann, H; Walter, M; Wang, Y R; Wendt, C; Wiebusch, C; Wikström, G; Williams, D R; Wischnewski, R; Wissing, H; Woschnagg, K; Xu, X W; Yodh, G; Yoshida, S; De Dios-Zornoza-Gomez, Juan

    2007-01-01

    Using the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades from gamma-ray bursts. No evidence of astrophysical neutrinos was found, and limits are presented for several models. We also present neutrino effective areas which allow the calculation of limits for any neutrino production model. The first analysis looked for a statistical excess of events within a sliding window of 1 or 100 seconds (for short and long burst classes, respectively) during the years 2001-2003. The resulting upper limit on the diffuse flux normalization times E^2 for the Waxman-Bahcall model at 1 PeV is 1.6 x 10^-6 GeV cm^-2 s^-1 sr^-1. For this search 90% of the neutrinos would fall in the energy range 50 TeV to 7 PeV. The second analysis looked for neutrino-induced cascades in coincidence with 73 bursts detected by BATSE in the year 2000. The resulting upper limit on the diffuse flux normalization times E^2, also at 1 PeV, is 1.5 x 10^-6 GeV cm^-2 s^-1 sr^-1 for the same energy rang...

  10. Search for neutrino-induced cascades with five years of AMANDA data

    NARCIS (Netherlands)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Actis, O.; Adams, J.; Aguilar, J.A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S.W.; Bay, R.; Alba, J.L.B.; Beattie, K.; Beatty, J.J.; Bechet, S.; Becker, J.K.; Becker, K.H.; Benabderrahmane, M.L.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D.Z.; Bissok, M.; Blaufuss, E.; Boersma, D.J.; Bohm, C.; Boser, S.; Botner, O.; Bradley, L.; Braun, J.; Buitirik, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D.F.; D'Agostino, M.V.; Danninger, M.; Davis, J.C.; Clercq, C. De; Demirors, L.; Depaepe, O.; Descamps, F.; Desiati, P.; Vries-Uiterweerd, G. de; DeYoung, T.; Diaz-Velez, J.C.; Dreyer, J.; Dumm, J.P.; Duvoort, M.R.; Ehrlich, R.; Eisch, J.; Ellsworth, R.W.; Engdegard, O.; Euler, S.; Evenson, P.A.; Fadiran, O.; Fazely, A.R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M.M.; Fox, B.D.; Franckowiak, A.; Franke, R.; Gaisser, T.K.; Gallagher, J.; Ganugapati, R.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glusenkamp, T.; Goldschmidt, A.; Goodman, J.A.; Grant, D.; Griesel, T.; Gross, A.; Grullon, S.; Gunasingha, R.M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G.C.; Hoffman, K.D.; Homeier, A.; Hoshina, K.; Hubert, D.; Lafebre, S.J.

    2011-01-01

    We report on the search for electromagnetic and hadronic showers ("cascades") produced by a diffuse flux of extraterrestrial neutrinos in the AMANDA neutrino telescope. Data for this analysis were recorded during 1001 days of detector livetime in the years 2000-2004. The observed event rates are con

  11. Search for tau-neutrino induced cascades in the IceCube detector

    Energy Technology Data Exchange (ETDEWEB)

    Usner, Marcel; Kowalski, Marek [DESY, Zeuthen (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The IceCube Neutrino Observatory at the South Pole is a Cherenkov detector built to measure high-energy neutrinos from cosmic sources. A total volume of about one cubic kilometer of the Antarctic ice is instrumented with 5160 optical modules. A tau lepton is created in the charged current interaction of a tau neutrino with an ice nucleus. The Double Bang signature links two subsequent cascades from the hadronic interaction and the tau decay within the detection volume. It can only be resolved at the highest energies around 1 PeV where the decay length of the tau is about 50 m. The work is focused on optimizing reconstruction methods of Double Bang events incorporating the latest ice model. The goal is to measure a flavor ratio that, for the first time, is sensitive to tau neutrinos.

  12. Search for neutrino-induced cascades with five years of AMANDA data

    Science.gov (United States)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Actis, O.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Böser, S.; Botner, O.; Bradley, L.; Braun, J.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Imlay, R. L.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lehmann, R.; Lennarz, D.; Lünemann, J.; Madsen, J.; Majumdar, P.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.

    2011-01-01

    We report on the search for electromagnetic and hadronic showers (“cascades”) produced by a diffuse flux of extraterrestrial neutrinos in the AMANDA neutrino telescope. Data for this analysis were recorded during 1001 days of detector livetime in the years 2000-2004. The observed event rates are consistent with the background expectation from atmospheric neutrinos and muons. An upper limit is derived for the diffuse flux of neutrinos of all flavors assuming a flavor ratio of νe:νμ:ντ = 1:1:1 at the detection site. The all-flavor flux of neutrinos with an energy spectrum Φ ∝ E-2 is less than 5.0 × 10-7 GeV s-1 sr-1 cm-2 at a 90% C.L. Here, 90% of the simulated signal would fall within the energy range 40 TeV to 9 PeV. We discuss flux limits in the context of several specific models of extraterrestrial and prompt atmospheric neutrino production.

  13. Charge-Separated Atmospheric Neutrino-Induced Muons in the MINOS Far Detector

    CERN Document Server

    Adamson, P; Arms, K E; Armstrong, R; Auty, D J; Avvakumov, S; Ayres, D S; Baller, B; Barish, B; Barnes, P D; Barr, G; Barrett, W L; Beall, E; Becker, B R; Belias, A; Bergfeld, T; Bernstein, R H; Bhattacharya, D; Bishai, M; Blake, A; Bock, B; Bock, G J; Bogert, D; Border, P M; Bower, C; Buckley-Geer, E; Böhm, J; Böhnlein, D J; Cabrera, A; Chapman, J D; Cherdack, D; Childress, S; Choudhary, B C; Cobb, J H; Culling, A J; De Jong, J K; De Santo, A; Dierckxsens, M; Diwan, M V; Dorman, M; Drakoulakos, D; Durkin, T; Erwin, A R; Escobar, C O; Evans, J J; Falk-Harris, E; Feldman, G J; Fields, T H; Ford, R; Frohne, M V; Gallagher, H R; Giurgiu, G A; Godley, A; Gogos, J; Goodman, M C; Gouffon, P; Gran, R; Grashorn, E W; Grossman, N; Grzelak, K; Habig, A; Harris, D; Harris, P G; Hartnell, J; Hartouni, E P; Hatcher, R; Heller, K; Holin, A; Howcroft, C; Hylen, J; Indurthy, D; Irwin, G M; Ishitsuka, M; Jaffe, D E; James, C; Jenner, L; Jensen, D; Joffe-Minor, T; Kafka, T; Kang, H J; Kasahara, S M; Kim, M S; Koizumi, G; Kopp, S; Kordosky, M; Koskinen, D J; Kotelnikov, S K; Kreymer, A; Kumaratunga, S; Lang, K; Lebedev, A; Lee, R; Ling, 6J; Litchfield, P J; Litchfield, R P; Liu, J; Lucas, P; Mann, W A; Marchionni, A; Marino, A D; Marshak, M L; Marshall, J S; Mayer, N; McGowan, A M; Meier, J R; Merzon, G I; Messier, M D; Michael, D G; Milburn, R H; Miller, J L; Miller, W H; Mishra, S R; Mislivec, A; Miyagawa, P S; Moore, C D; Morfin, J; Mualem, L; Mufson, S; Murgia, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nicholls, T C; Ochoa-Ricoux, J P; Oliver, W P; Osiecki, T; Ospanov, R; Paley, J; Paolone, V; Para, A; Patzak, T; Pavlovic, Z; Pearce, G F; Peck, C W; Peterson, E A; Petyt, D A; Ping, H; Piteira, R; Pittam, R; Plunkett, R K; Rahman, D; Rameika, R A; Raufer, T M; Rebel, B; Reichenbacher, J; Reyna, D E; Rosenfeld, C; Rubin, H A; Ruddick, K; Ryabov, V A; Saakyan, R; Sanchez, M C; Saoulidou, N; Schneps, J; Schreiner, P; Semenov, V K; Seun, S M; Shanahan, P; Smart, W; Smirnitsky, V; Smith, C; Sousa, A; Speakman, B; Stamoulis, P; Symes, P A; Tagg, N; Talaga, R L; Tetteh-Lartey, E; Thomas, J; Thompson, J; Thomson, M A; Thron, J L; Tinti, G; Trostin, I; Tsarev, V A; Tzanakos, G; Urheim, J; Vahle, P; Verebryusov, V; Viren, B; Ward, C P; Ward, D R; Watabe, M; Webb, R C; Weber, A; Wehmann, A; West, N; White, C; Wojcicki, S G; Wright, D M; Wu, Q K; Yang, T; Yumiceva, F X; Zheng, H; Zois, M; Zwaska, R

    2007-01-01

    We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios is consistent with an oscillation signal. A fit to the data for the oscillation parameters excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons by charge sign in both the data and Monte Carlo events and found the ratio of the total number of negative to positive muons in both samples. The ratio of those ratios is a test of CPT conservation. The result is consistent with CPT conservation.

  14. Search for neutrino-induced particle showers with IceCube-40

    CERN Document Server

    Aartsen, M G; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Arguelles, C; Arlen, T C; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beatty, J J; Tjus, J Becker; Becker, K -H; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Brayeur, L; Bretz, H -P; Brown, A M; Bruijn, R; Casey, J; Casier, M; Chirkin, D; Christov, A; Christy, B; Clark, K; Classen, L; Clevermann, F; Coenders, S; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; De Ridder, S; Desiati, P; de Vries, K D; de With, M; DeYoung, T; Díaz-Vélez, J C; Dunkman, M; Eagan, R; Eberhardt, B; Eichmann, B; Eisch, J; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Goodman, J A; Góra, D; Grandmont, D T; Grant, D; Gretskov, P; Groh, J C; Groß, A; Ha, C; Ismail, A Haj; Hallen, P; Hallgren, A; Halzen, F; Hanson, K; Hebecker, D; Heereman, D; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huang, F; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Jagielski, K; Japaridze, G S; Jero, K; Jlelati, O; Kaminsky, B; Kappes, A; Karg, T; Karle, A; Kauer, M; Kelley, J L; Kiryluk, J; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kriesten, A; Krings, K; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Leute, J; Lünemann, J; Macías, O; Madsen, J; Maggi, G; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Paul, L; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Quinnan, M; Rädel, L; Rameez, M; Rawlins, K; Redl, P; Reimann, R; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Robertson, S; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Sestayo, Y; Seunarine, S; Shanidze, R; Sheremata, C; Smith, M W E; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stanisha, N A; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Strotjohann, N L; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Toscano, S; Tselengidou, M; Unger, E; Usner, M; Vallecorsa, S; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Weaver, Ch; Wellons, M; Wendt, C; Westerhoff, S; Whelan, B; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zoll, M

    2013-01-01

    We report on the search for neutrino-induced particle-showers, so-called cascades, in the IceCube-40 detector. The data for this search was collected between April 2008 and May 2009 when the first 40 IceCube strings were deployed and operational. Three complementary searches were performed, each optimized for different energy regimes. The analysis with the lowest energy threshold (2 TeV) targeted atmospheric neutrinos. A total of 67 events were found, consistent with the expectation of 41 atmospheric muons and 30 atmospheric neutrino events. The two other analyses targeted a harder, astrophysical neutrino flux. The analysis with an intermediate threshold of 25 TeV lead to the observation of 14 cascade-like events, again consistent with the prediction of 3.0 atmospheric neutrino and 7.7 atmospheric muon events. We hence set an upper limit of $E^2 \\Phi_{lim} \\leq 7.46\\times10^{-8}\\,\\mathrm{GeV sr^{-1} s^{-1} cm^{-2}}$ (90% C.L.) on the diffuse flux from astrophysical neutrinos of all neutrino flavors, applicabl...

  15. Neutrino induced 1-pion production

    CERN Document Server

    González-Jiménez, R; Van Dessel, N; Pandey, V; Jachowicz, N

    2016-01-01

    Neutrino-induced pion production constitutes an important contribution to neutrino-nucleus scattering cross sections at intermediate energies. A deep understanding of this process is mandatory for a correct interpretation of neutrino-oscillation experiments. We aim at contributing to the ongoing effort to understand the various experimental results obtained by different collaborations in a wide range of energies. In particular, in this work we analyze recent MiniBooNE and MINERvA charged-current neutrino 1-pion production data. We use a relativistic theoretical approach which accounts for resonant and non-resonant 1-pion production contributions.

  16. Search for neutrino-induced particle showers with IceCube-40

    DEFF Research Database (Denmark)

    Aartsen, M.G.; Abbasi, R.; Ackermann, M.

    2014-01-01

    We report on the search for neutrino-induced particle-showers, so-called cascades, in the IceCube-40 detector. The data for this search was collected between April 2008 and May 2009 when the first 40 IceCube strings were deployed and operational. Three complementary searches were performed, each...

  17. Neutrino-induced coherent pion production

    CERN Document Server

    Alvarez-Ruso, L; Hirenzaki, S; Vacas, M J Vicente; Leitner, T; Mosel, U

    2007-01-01

    We have investigated the neutrino induced coherent pion production reaction at the energies of interest for recent experiments like K2K and MiniBooNE. The model includes pion, nucleon and the Delta(1232) resonance. Medium effects in the production mechanism and the distortion of the pion wave function are taken into account. We find a strong reduction of the cross section due to these effects and also substantial modifications in the energy distributions of the final pion. The sensitivity of the results on the axial N-Delta coupling C5A(0) and the coherent fraction in neutral-current pi0 production are discussed.

  18. Charged current neutrino induced coherent pion production

    CERN Document Server

    Alvarez-Ruso, L; Hirenzaki, S; Vacas, M J V

    2007-01-01

    We analyze the neutrino induced charged current coherent pion production at the energies of interest for recent experiments like K2K and MiniBooNE. Medium effects in the production mechanism and the distortion of the pion wave function, obtained solving the Klein Gordon equation with a microscopic optical potential, are included in the calculation. We find a strong reduction of the cross section due to these effects and also substantial modifications of the energy distributions of the final lepton and pion.

  19. Nuclear effects in neutrino induced reactions

    CERN Document Server

    Vacas, M J Vicente; Geng, L S; Nieves, J; Valverde, M; Hirenzaki, S

    2008-01-01

    We discuss the relevance of nuclear medium effects in the analysis of some low and medium energy neutrino reactions of current interest. In particular, we study the Quasi-Elastic (QE) process, where RPA correlations and Final State Interactions (FSI) are shown to play a crucial role. We have also investigated the neutrino induced coherent pion production. We find a strong reduction of the cross section due to the distortion of the pion wave function and the modification of the production mechanisms in the nucleus. The sensitivity of the results to the axial $N\\Delta$ coupling $C_5^A(0)$ has been also investigated.

  20. Numerical Physical Mechanism and Model of Turbulent Cascades in a Barotropic Atmosphere

    Institute of Scientific and Technical Information of China (English)

    黄锋; 刘式适

    2004-01-01

    In a barotropic atmosphere,new Reynolds mean momentum equations including turbulent viscosity,dispersion,and instability are used not only to derive the KdV-Burgers-Kuramoto equation but also to analyze the physical mechanism of the cascades of energy and enstrophy.It shows that it is the effects of dispersion and instability that result in the inverse cascade.Then based on the conservation laws of the energy and enstrophy,a cascade model is put forward and the processes of the cascades are described.

  1. Neutrino-induced reactions on nuclei

    Science.gov (United States)

    Gallmeister, K.; Mosel, U.; Weil, J.

    2016-09-01

    Background: Long-baseline experiments such as the planned deep underground neutrino experiment (DUNE) require theoretical descriptions of the complete event in a neutrino-nucleus reaction. Since nuclear targets are used this requires a good understanding of neutrino-nucleus interactions. Purpose: Develop a consistent theory and code framework for the description of lepton-nucleus interactions that can be used to describe not only inclusive cross sections, but also the complete final state of the reaction. Methods: The Giessen-Boltzmann-Uehling-Uhlenbeck (GiBUU) implementation of quantum-kinetic transport theory is used, with improvements in its treatment of the nuclear ground state and of 2p2h interactions. For the latter an empirical structure function from electron scattering data is used as a basis. Results: Results for electron-induced inclusive cross sections are given as a necessary check for the overall quality of this approach. The calculated neutrino-induced inclusive double-differential cross sections show good agreement data from neutrino and antineutrino reactions for different neutrino flavors at MiniBooNE and T2K. Inclusive double-differential cross sections for MicroBooNE, NOvA, MINERvA, and LBNF/DUNE are given. Conclusions: Based on the GiBUU model of lepton-nucleus interactions a good theoretical description of inclusive electron-, neutrino-, and antineutrino-nucleus data over a wide range of energies, different neutrino flavors, and different experiments is now possible. Since no tuning is involved this theory and code should be reliable also for new energy regimes and target masses.

  2. Numerical calculations of cosmic ray cascade in the Earth's atmosphere using different particle interaction models

    Science.gov (United States)

    Nesterenok, A. V.; Naidenov, V. O.

    2015-12-01

    The interaction of primary cosmic rays with the Earth's atmosphere is investigated using the simulation toolkit GEANT4. Two reference lists of physical processes - QGSP_BIC_HP and FTFP_BERT_HP - are used in the simulations of cosmic ray cascade in the atmosphere. The cosmic ray neutron fluxes are calculated for mean level of solar activity, high geomagnetic latitudes and sea level. The calculated fluxes are compared with the published results of other analogous simulations and with experimental data.

  3. Neutrino Induced Coherent ρ Production in a Fine Grained Tracker

    Science.gov (United States)

    Jiang, Libo; Kullenberg, Christpher; Tian, Xinchun; Mishra, Sanjib; LBNE Collaboration

    2015-04-01

    We present simulation of neutrino induced coherent ρ-meson production in charged and neutral current interactions. Sensitivity studies of this process is presented in a fine grain tracker, a near detector option for LBNE. Measurements of coherent ρ0 and ρ+ production in NOMAD are reported.

  4. Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory

    Science.gov (United States)

    SNO collaboration; Aharmim, B.; Ahmed, S. N.; Andersen, T. C.; Anthony, A. E.; Barros, N.; Beier, E. W.; Bellerive, A.; Beltran, B.; Bergevin, M.; Biller, S. D.; Boudjemline, K.; Boulay, M. G.; Burritt, T. H.; Cai, B.; Chan, Y. D.; Chen, M.; Chon, M. C.; Cleveland, B. T.; Cox-Mobrand, G. A.; Currat, C. A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Detwiler, J.; Doe, P. J.; Dosanjh, R. S.; Doucas, G.; Drouin, P.-L.; Duncan, F. A.; Dunford, M.; Elliott, S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Fleurot, F.; Ford, R. J.; Formaggio, J. A.; Gagnon, N.; Goon, J. TM.; Grant, D. R.; Guillian, E.; Habib, S.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hargrove, C. K.; Harvey, P. J.; Harvey, P. J.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.; Helmer, R. L.; Hemingway, R. J.; Henning, R.; Hime, A.; Howard, C.; Howe, M. A.; Huang, M.; Jamieson, B.; Jelley, N. A.; Klein, J. R.; Kos, M.; Kruger, A.; Kraus, C.; Krauss, C. B.; Kutter, T.; Kyba, C. C. M.; Lange, R.; Law, J.; Lawson, I. T.; Lesko, K. T.; Leslie, J. R.; Levine, I.; Loach, J. C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H. B.; Maneira, J.; Marino, A. D.; Martin, R.; McCauley, N.; McDonald, A. B.; McGee, S.; Mifflin, C.; Miller, M. L.; Monreal, B.; Monroe, J.; Noble, A. J.; Oblath, N. S.; Okada, C. E.; O'Keeffe, H. M.; Opachich, Y.; Orebi Gann, G. D.; Oser, S. M.; Ott, R. A.; Peeters, S. J. M.; Poon, A. W. P.; Prior, G.; Rielage, K.; Robertson, B. C.; Robertson, R. G. H.; Rollin, E.; Schwendener, M. H.; Secrest, J. A.; Seibert, S. R.; Simard, O.; Simpson, J. J.; Sinclair, D.; Skensved, P.; Smith, M. W. E.; Sonley, T. J.; Steiger, T. D.; Stonehill, L. C.; Tagg, N.; Tesic, G.; Tolich, N.; Tsui, T.; Van de Water, R. G.; VanDevender, B. A.; Virtue, C. J.; Waller, D.; Waltham, C. E.; Wan Chan Tseung, H.; Wark, D. L.; Watson, P.; Wendland, J.; West, N.; Wilkerson, J. F.; Wilson, J. R.; Wouters, J. M.; Wright, A.; Yeh, M.; Zhang, F.; Zuber, K.

    2009-07-10

    Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between -1 {le} cos {theta}{sub zenith} 0.4 in a total exposure of 2.30 x 10{sup 14} cm{sup 2} s. The measured flux normalization is 1.22 {+-} 0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos {theta}{sub zenith} > 0.4 is measured to be (3.31 {+-} 0.01 (stat.) {+-} 0.09 (sys.)) x 10{sup -10} {micro}/s/cm{sup 2}.

  5. Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory

    Energy Technology Data Exchange (ETDEWEB)

    SNO collaboration; Aharmim, B.; Ahmed, S.N.; Andersen, T.C.; Anthony, A.E.; Barros, N.; Beier, E.W.; Bellerive, A.; Beltran, B.; Bergevin, M.; Biller, S.D.; Boudjemline, K.; Boulay, M.G.; Burritt, T.H.; Cai, B.; Chan, Y.D.; Chen, M.; Chon, M.C.; Cleveland, B.T.; Cox-Mobrand, G.A.; Currat, C.A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Detwiler, J.; Doe, P.J.; Dosanjh, R.S.; Doucas, G.; Drouin, P.-L.; Duncan, F.A.; Dunford, M.; Elliott, S.R.; Evans, H.C.; Ewan, G.T.; Farine, J.; Fergani, H.; Fleurot, F.; Ford, R.J.; Formaggio, J.A.; Gagnon, N.; Goon, J.TM.; Grant, D.R.; Guillian, E.; Habib, S.; Hahn, R.L.; Hallin, A.L.; Hallman, E.D.; Hargrove, C.K.; Harvey, P.J.; Harvey, P.J.; Heeger, K.M.; Heintzelman, W.J.; Heise, J.; Helmer, R.L.; Hemingway, R.J.; Henning, R.; Hime, A.; Howard, C.; Howe, M.A.; Huang, M.; Jamieson, B.; Jelley, N.A.; Klein, J.R.; Kos, M.; Kruger, A.; Kraus, C.; Krauss, C.B.; Kutter, T.; Kyba, C.C.M.; Lange, R.; Law, J.; Lawson, I.T.; Lesko, K.T.; Leslie, J.R.; Levine, I.; Loach, J.C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H.B.; Maneira, J.; Marino, A.D.; Martin, R.; McCauley, N.; McDonald, A.B.; McGee, S.; Mifflin, C.; Miller, M.L.; Monreal, B.; Monroe, J.; Noble, A.J.; Oblath, N.S.; Okada, C.E.; O?Keeffe, H.M.; Opachich, Y.; Orebi Gann, G.D.; Oser, S.M.; Ott, R.A.; Peeters, S.J.M.; Poon, A.W.P.; Prior, G.; Rielage, K.; Robertson, B.C.; Robertson, R.G.H.; Rollin, E.; Schwendener, M.H.; Secrest, J.A.; Seibert, S.R.; Simard, O.; Simpson, J.J.; Sinclair, D.; Skensved, P.; Smith, M.W.E.; Sonley, T.J.; Steiger, T.D.; Stonehill, L.C.; Tagg, N.; Tesic, G.; Tolich, N.; Tsui, T.; Van de Water, R.G.; VanDevender, B.A.; Virtue, C.J.; Waller, D.; Waltham, C.E.; Wan Chan Tseung, H.; Wark, D.L.; Watson, P.; Wendland, J.; West, N.; Wilkerson, J.F.; Wilson, J.R.; Wouters, J.M.; Wright, A.; Yeh, M.; Zhang, F.; Zuber, K.

    2009-02-16

    Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between -1 {le} cos {theta}{sub zenith} 0.4 in a total exposure of 2.30 x 10{sup 14} cm{sup 2} s. The measured flux normalization is 1.22 {+-} 0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cos {theta}{sub zenith} > 0.4 is measured to be (3.31 {+-} 0.01 (stat.) {+-} 0.09 (sys.)) x 10{sup -10} {micro}/s/cm{sup 2}.

  6. Application of cascade lasers to detection of trace gaseous atmospheric pollutants

    Science.gov (United States)

    Miczuga, Marcin; Kopczyński, Krzysztof

    2016-12-01

    Understanding the impact of gaseous pollutants on the earth's atmosphere, as well as more and more felt by mankind negative effects of its contamination, result in increasing the level of environmental awareness and contribute to the intensification of actions aimed at reducing the emission of harmful gases into the atmosphere. At the same time, the extensive studies are conducted in order to continuously monitor the level of air contamination with harmful gases and the industry compliance with the standards limited the amount of emitted pollutants. Over recent years, there has been increasing use of cascade lasers and multi-pass cells in optical systems detecting the gaseous atmospheric pollutants and measuring the gas concentrations. The paper presents the use of a tunable quantum cascade laser as a source of the IR radiation in an advanced detection system enabling the trace gaseous atmospheric pollutants to be identified. Apart from the laser, the main elements of the system are: a multi-pass cell, an IR detector and a module for control and analysis. Operation of the system is exemplified by measuring the level of the air pollution with ammonia, carbon oxide and nitrous oxide.

  7. Comparison between methods for the determination of the primary cosmic ray mass composition from the longitudinal profile of atmospheric cascades

    CERN Document Server

    Ambrosio, M; Donalek, C; D'Urso, D; Erlykin, A D; Guarino, F; Insoiia, A; Longo, G

    2005-01-01

    The determination of the primary cosmic ray mass composition from the longitudinal development of atmospheric cascades is still a debated issue. In this work we discuss several data analysis methods and show that if the entire information contained in the longitudinal profile is exploited, reliable results may be obtained. Among the proposed methods FCC ('Fit of the Cascade Curve'), MTA ('Multiparametric Topological Analysis') and NNA ('Neural Net Analysis') with conjugate gradient optimization algorithm give the best accuracy.

  8. Transition radiation at radio frequencies from ultra-high energy neutrino-induced showers

    CERN Document Server

    Motloch, Pavel; Privitera, Paolo; Zas, Enrique

    2015-01-01

    Coherent radiation at radio frequencies from high-energy showers fully contained in a dense radio-transparent medium - like ice, salt or regolith - has been extensively investigated as a promising technique to search for ultra-high energy (UHE) neutrinos. Additional emission in the form of transition radiation may occur when a neutrino-induced shower produced close to the Earth surface emerges from the ground into atmospheric air. We present the first detailed evaluation of transition radiation from high-energy showers crossing the boundary between two different media. We found that transition radiation is sizable over a wide solid angle and coherent up to $\\sim$ 1 GHz. These properties encourage further work to evaluate the potential of a large-aperture UHE neutrino experiment based on detection of transition radiation.

  9. Open-path, quantum cascade laser-based sensor for high resolution atmospheric ammonia measurements

    Directory of Open Access Journals (Sweden)

    D. J. Miller

    2013-07-01

    Full Text Available We demonstrate a compact, open-path, quantum cascade laser-based atmospheric ammonia sensor operating at 9.06 μm for high sensitivity, high temporal resolution, ground-based measurements. Atmospheric ammonia (NH3 is a gas-phase precursor to fine particulate matter, with implications for air quality and climate change. Currently, NH3 sensing challenges have led to a lack of widespread in-situ measurements. Our open-path sensor configuration avoids sampling artifacts associated with NH3 surface adsorption onto inlet tubing and reduced pressure sampling cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic wavelength modulation spectroscopy allows for selective and sensitive detection of atmospheric-pressure broadened absorption features. An in-line ethylene reference cell provides real-time calibration (±20% accuracy and normalization for instrument drift under rapidly changing field conditions. The sensor has a sensitivity and minimum detection limit of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and consumes ~ 50 W of electrical power. In-situ field performance of this open-path NH3 sensor is demonstrated, with 10 Hz time resolution and a large dynamic response for in-situ NH3 measurements. This sensor provides the capabilities for improved in-situ gas phase NH3 sensing relevant for emission source characterization and flux measurements.

  10. Relations between atmospheric circulation and mass balance of South Cascade Glacier, Washington, USA

    Science.gov (United States)

    McCabe, G.J.; Fountain, A.G.

    1995-01-01

    The yearly net mass balance of South Cascade Glacier, Washington, has decreased since the mid-1970s. Resuls show that the decrease is primarily caused by a significant decrease in the winter mass balance. Changes in atmospheric circulation indicate a decrease in the movement of storms and moisture from the Pacific Ocean into the western contiguous United States. In addition, the increase in winter mean 700-mb heights over western Canada and the northern western contiguous United States indicates an increase in subsidence, which results in a warming and drying of the air that further reduces precipitation and also increases the ratio of rain to snow during the cold season. These factors contribute to below-average winter mass balances. -from Authors

  11. Demonstration of a rapidly-swept external cavity quantum cascade laser for atmospheric sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.; Suter, Jonathan D.

    2016-07-01

    The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (~10 cm-1) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges >100 cm-1, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (~100 cm-1) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple chemical

  12. Neutrino Induced Coherent Pion Production off Nuclei and PCAC

    CERN Document Server

    Hernández, E; Vicente-Vacas, M J

    2009-01-01

    We have critically reviewed the commonly used Rein--Sehgal model for neutrino induced coherent pion production. We have studied the validity of the main approximations implicit in that model, trying to compare with physical observables when that is possible and with microscopical calculations. Next, we have tried to elaborate a new improved model by removing the more problematic approximations, while keeping the model still reasonably simple. Last, we have discussed the limitations intrinsic to any approach based on the partial conservation of the axial current hypothesis. In particular, we have shown the inability of such models to determine the angular distribution of the outgoing pion with respect to the direction of the incoming neutrino, except for the $q^2= 0$ kinematical point.

  13. Neutrino-induced Reactions and Neutrino Scattering with Nuclear Targets

    Science.gov (United States)

    Cheoun, Myung-Ki; Ha, Eunja; Yang, Ghil-Seok; Kim, Kyungsik; Kajino, T.

    2016-02-01

    We reviewed present status regarding experimental data and theoretical approaches for neutrino-induced reactions and neutrino scattering. With a short introduction of relevant data, our recent calculations by distorted-wave Born approximation for quasielastic region are presented for MiniBooNE data. For much higher energy neutrino data, such as NOMAD data, elementary process approach was shown to be useful instead of using complicated nuclear models. But, in the low energy region, detailed nuclear structure model, such as QRPA and shell model, turn out to be inescapable to explain the reaction data. Finally, we discussed that one step-process in the reaction is comparable to the two-step process, which has been usually used in the neutrino-nucleosynthesis.

  14. Neutrino-induced Reactions and Neutrino Scattering with Nuclear Targets

    Directory of Open Access Journals (Sweden)

    Cheoun Myung-Ki

    2016-01-01

    Full Text Available We reviewed present status regarding experimental data and theoretical approaches for neutrino-induced reactions and neutrino scattering. With a short introduction of relevant data, our recent calculations by distorted-wave Born approximation for quasielastic region are presented for MiniBooNE data. For much higher energy neutrino data, such as NOMAD data, elementary process approach was shown to be useful instead of using complicated nuclear models. But, in the low energy region, detailed nuclear structure model, such as QRPA and shell model, turn out to be inescapable to explain the reaction data. Finally, we discussed that one step-process in the reaction is comparable to the two-step process, which has been usually used in the neutrino-nucleosynthesis.

  15. Downscale cascades in tracer transport test cases: an intercomparison of the dynamical cores in the Community Atmosphere Model CAM5

    Directory of Open Access Journals (Sweden)

    J. Kent

    2012-07-01

    Full Text Available The accurate modelling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the Western Hemisphere should not pass into the Eastern Hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.

    An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the Eastern Hemisphere of the separate cells test.

  16. Downscale cascades in tracer transport test cases: an intercomparison of the dynamical cores in the Community Atmosphere Model CAM5

    Directory of Open Access Journals (Sweden)

    J. Kent

    2012-12-01

    Full Text Available The accurate modeling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the western hemisphere should not pass into the eastern hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.

    An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the eastern hemisphere of the separate cells test.

  17. Neutrino-induced pion production from nuclei at medium energies

    CERN Document Server

    Praet, C; Jachowicz, N; Ryckebusch, J

    2008-01-01

    We present a fully relativistic formalism for describing neutrino-induced $\\Delta$-mediated single-pion production from nuclei. We assess the ambiguities stemming from the $\\Delta$ interactions. Variations in the cross sections of over 10% are observed, depending on whether or not magnetic-dipole dominance is assumed to extract the vector form factors. These uncertainties have a direct impact on the accuracy with which the axial-vector form factors can be extracted. Different predictions for $C_5^A(Q^2)$ induce up to 40-50% effects on the $\\Delta$-production cross sections. To describe the nucleus, we turn to a relativistic plane-wave impulse approximation (RPWIA) using realistic bound-state wave functions derived in the Hartree approximation to the $\\sigma$-$\\omega$ Walecka model. For neutrino energies larger than 1 GeV, we show that a relativistic Fermi-gas model with appropriate binding-energy correction produces comparable results as the RPWIA which naturally includes Fermi motion, nuclear-binding effects...

  18. Charged and Neutral Current Neutrino Induced Nucleon Emission Reactions

    CERN Document Server

    Nieves, J; Vacas, M J V

    2006-01-01

    By means of a Monte Carlo cascade method, to account for the rescattering of the outgoing nucleon, we study the charged and neutral current inclusive one nucleon knockout reactions off nuclei induced by neutrinos. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, and can be used in the analysis of future neutrino experiments.

  19. Jets and macroturbulent "cascades" in atmospheres, oceans and the laboratory (Lewis Fry Richardson Medal Lecture)

    Science.gov (United States)

    Read, Peter L.

    2016-04-01

    The banded organization of clouds associated with intense zonal (east-west) jet streams and large-scale oval vortices on Jupiter and Saturn have long fascinated astronomers and atmospheric dynamicists for many years. The current view is that these features are a manifestation of strongly anisotropic energy transfers within a highly turbulent fluid on a rapidly rotating, spherical planet that is energised at relatively small scales, either by free convection or baroclinic instabilities. The details are still not fully understood, however. Energy exchanges in the Earth's atmosphere and oceans, and on other planets, are similarly complex, with evidence of both upscale and downscale transfers and formation of zonal jet-like features. In this lecture we will explore insights from laboratory experiments on both small scales and on the Coriolis platform in Grenoble, France that investigate plausible physical analogues of such atmospheric or oceanic circulations, energized mainly by free thermal convection with strong background rotation. Weak, eddy-driven jets may be obtained through anisotropic energy exchanges, though (for reasons to be discussed) it is not possible to match Jupiter's parameter regime very closely in the laboratory. We will compare the dynamics and energetics of our laboratory experiment with new measurements of energy exchanges, spectra and structure functions in Jupiter's atmosphere from analysis of Cassini spacecraft images, which indicate some new directions for models of gas giant atmospheric circulations.

  20. Neutrino - Induced Muons in the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Rebel, Brian J. [Indiana Univ., Bloomington, IN (United States)

    2004-08-25

    The Main Injector Neutrino Oscillation Search (MINOS) is an experiment designed to probe the phenomenon of neutrino oscillations. When MINOS is completed it will consist of a neutrino beam and two detectors, which are separated by a distance of 735 km. The near detector measures the energy distribution and ux of a beam of muon neutrinos produced at Fermilab, while the far detector, located in Soudan, MN, measures these same neutrino properties 735 km away. The signal for a detection of neutrino oscillations is a de cit of neutrinos at the far detector compared to expectations based on the near detector measurements. In addition to measuring beam neutrinos, the far detector can be used to measure neutrinos produced in cosmic ray interactions in the atmosphere. While waiting for the beam to begin running, the far detector was used in this mode. Several previous experiments, such as Super-K and MACRO, have suggested that the atmospheric neutrinos oscillate between di erent avor states. This dissertation looks for an oscillation signal in the atmospheric neutrinos by using muons resulting from the interaction of the atmospheric neutrinos in the rock surrounding the MINOS far detector.

  1. Neutrino induced pion production at MiniBooNE and K2K energies

    CERN Document Server

    Leitner, T; Mosel, U; Alvarez-Ruso, L

    2009-01-01

    We investigate charged and neutral current neutrino-induced incoherent pion production off nuclei within the GiBUU model at energies relevant for the MiniBooNE and K2K experiments. Special attention is paid to the entanglement between measured CCQE and CC1pi+ cross sections. We further give predictions and compare to recent data measured at MiniBooNE.

  2. Mapping Atmospheric Ammonia Emissions Using a Mobile Quantum Cascade Laser-based Open-path Sensor

    Science.gov (United States)

    Sun, K.; Tao, L.; Miller, D. J.; Khan, M. A.; Zondlo, M. A.

    2012-12-01

    Ammonia (NH3) is a key precursor to atmospheric fine particulate matter, with strong implications for regional air quality and global climate change. Despite the importance of atmospheric ammonia, its spatial/temporal variation is poorly characterized, and the knowledge of its sources, sinks, and transport is severely limited. Existing measurements suggest that traffic exhaust may provide significant amounts of ammonia in urban areas, which cause greater impacts on particulate matter formation and urban air quality. To capture the spatial and temporal variation of ammonia emissions, a portable, low power sensor with high time resolution is necessary. We have developed a portable open-path ammonia sensor with a detection limit of 0.5 ppbv ammonia for 1 s measurements. The sensor has a power consumption of about 60 W and is capable of running on a car battery continuously for 24 hours. An additional laser has been coupled to the sensor to yield concurrent N2O and CO measurements as tracers for determining various sources. The overall sensor prototype fits on a 60 cm × 20 cm aluminum breadboard. Roadside measurements indicated NH3/CO emission ratios of 4.1±5.4 ppbv/ppmv from a fleet of 320 vehicles, which agree with existing on-ramp measurements. Urban measurements in the Baltimore and Washington, DC metropolitan areas have shown significant ammonia mixing ratios concurrent with carbon monoxide levels from the morning and evening rush hours. On-road measurements of our open-path sensor have also been performed continuously from the Midwest to Princeton, NJ including urban areas such as Pittsburgh, tunnels, and relatively clean conditions. The emission ratios of ammonia against CO and/or CO2 help identify the sources and amounts of both urban and agricultural ammonia emissions. Preliminary data from both spatial mapping, monitoring, and vehicle exhaust measurements suggest that urban ammonia emissions from fossil fuel combustion are significant and may provide an

  3. Atmospheric ammonia measurements in Houston, TX using an external cavity-quantum cascade laser-based sensor

    Science.gov (United States)

    Gong, L.; Lewicki, R.; Griffin, R. J.; Flynn, J. H.; Lefer, B. L.; Tittel, F. K.

    2010-12-01

    Ammonia (NH3) plays a significant role in atmospheric chemistry. It has many anthropogenic (e.g., agricultural crops and mineral fertilizers) and natural sources (e.g., animals, oceans, and vegetation) in the environment. In certain areas, industrial and motor vehicle activities also can contribute to increases in atmospheric NH3 levels. From a perspective of environmental concern, NH3 is a precursor of particulate matter (PM) because it can lead to production of ammonium salts (e.g., (NH4)2SO4 and NH4NO3) through chemical reactions with sulfuric and nitric acid. As a result, the abundance of NH3 in the atmosphere has a great impact on aerosol nucleation and composition. Despite this, NH3 is not regulated. It is crucial, however, to improve our understanding of the dynamics of NH3 in an industrial and urban area such as Greater Houston where atmospheric NH3 data are limited. In this study, a 10.4 µm external cavity quantum cascade laser (EC-QCL)-based sensor was developed and utilized. To monitor atmospheric NH3 at trace gas concentration levels, an amplitude modulated photo-acoustic spectroscopy (AM-PAS) technique was employed. The minimum detection limit obtained from the sensor is ~1.5 ppb for a 5-second data acquisition time. After averaging data over 300 seconds a sub-ppb NH3 concentration level can be achieved. The NH3 sensor has been deployed on the roof of a ~60-meter-high building (North Moody Tower) located on the University of Houston campus since November 2009. Several episodes of high NH3 concentrations were observed. For example, the sensor recorded a significant and lasting increase in NH3 concentrations (~21 ppb) on August 14, 2010, when a major accident occurred during the same time period on the Gulf Freeway (I-45) in Houston only 2 miles from the sampling site. The elevated concentration levels are assumed to be associated with NH3 generation from a chemical fire resulting from the collision involving two 18-wheelers, one carrying fertilizer

  4. Methane and nitrous oxide measurements onboard the UK Atmospheric Research Aircraft using quantum cascade laser spectrometry (QCL)

    Science.gov (United States)

    Muller, J. B.; O'Shea, S.; Dorsey, J.; Bauguitte, S.; Cain, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.

    2012-12-01

    A Aerodyne Research© Mini-Quantum Cascade Laser (QCL) spectrometer was installed on the UK Facility of Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft and employed during summer 2012. Methane (CH4) and nitrous oxide (N2O) concentrations were measured within the Arctic Circle as part of the MAMM project (Methane and other greenhouse gases in the Arctic - Measurements, process studies and Modelling) as well as around the UK as part of the ClearfLo project (Clean Air for London). A range of missions were flown, including deep vertical profiles up to the stratosphere, providing concentration profiles of CH4 and N2O, as well as low altitude level runs exploring near surface diffuse emission sources such as the wetlands in Arctic Lapland and point emissions sources such as gas platforms off the UK coast. Significant pollution plumes were observed both in the Arctic and around the UK with elevated CH4 concentrations, as well as enhanced CO, O3 and aerosol levels. The NAME Lagrangian particle dispersion model will be used to investigate the origins of these CH4 plumes to identify the locations of the emissions sources. The first set of flights using QCL on the FAAM research aircraft have been successful and regular in-flight calibrations (high/low span) and target concentrations were used to determine instrument accuracy and precision. Additional data quality control checks could be made by comparison with an onboard Los Gatos Fast Greenhouse Gas Analyser (FGGA) for CO2 and CH4 and provide the basis for further instrument development and implementation for future Arctic MAMM flights during spring and summer 2013.

  5. Neutrino induced pion production at MiniBooNE and K2K

    CERN Document Server

    Leitner, T; Mosel, U; Alvarez-Ruso, L

    2008-01-01

    We investigate charged and neutral current neutrino induced incoherent pion production off nuclei at MiniBooNE and K2K energies within the GiBUU model. We assume impulse approximation and treat the nucleus as a local Fermi gas of nucleons bound in a mean-field potential. In-medium spectral functions are also taken into account. The outcome of the initial neutrino nucleon reaction undergoes complex hadronic final state interactions. We present results for neutral current pi^0 and charged current pi^+ production and compare to MiniBooNE and K2K data.

  6. Neutrino-induced pion production at low energies and in the small $Q^2$ region

    CERN Document Server

    Paschos, E A

    2012-01-01

    We analyse neutrino-induced reactions in the small $Q^2$ region and for energies covering the production and decay of the delta resonance. One of our results is the agreement with the MiniBooNE data for $1\\pi^+$ and $1\\pi^0$ final states. In addition we present differential cross sections for charged and neutral currents and for proton and neutron targets. Finally, we present cross sections induced by muon and electron type neutrinos, where effects of the lepton masses are visible.

  7. Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

    Directory of Open Access Journals (Sweden)

    Banerjee Projjwal

    2016-01-01

    Full Text Available We summarize our studies on neutrino-driven nucleosynthesis in He shells of early core-collapse supernovae with metallicities of Z ≲ 10−3 Z⊙. We find that for progenitors of ∼ 11–15 M⊙, the neutrons released by 4He(ν¯ee, e+n3H in He shells can be captured to produce nuclei with mass numbers up to A ∼ 200. This mechanism is sensitive to neutrino emission spectra and flavor oscillations. In addition, we find two new primary mechanisms for neutrino-induced production of 9Be in He shells. The first mechanism produces 9Be via 7Li(n,γ8Li(n,γ9Li(e− ν¯ee9Be and relies on a low explosion energy for its survival. The second mechanism operates in progenitors of ∼ 8 M⊙, where 9Be can be produced directly via 7Li(3H, n09Be during the rapid expansion of the shocked Heshell material. The light nuclei 7Li and 3H involved in these mechanisms are produced by neutrino interactions with 4He. We discuss the implications of neutrino-induced nucleosynthesis in He shells for interpreting the elemental abundances in metal-poor stars.

  8. Characterizing a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of atmospheric ammonia

    Directory of Open Access Journals (Sweden)

    R. A. Ellis

    2009-12-01

    Full Text Available A compact, fast-response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of ammonia has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 0.5 L multiple pass absorption cell with an effective path length of 76 m. Detection is achieved using a thermoelectrically cooled Mercury Cadmium Telluride (HgCdTe infrared detector. A novel sampling inlet was used, consisting of a short, heated, quartz tube with a hydrophobic coating to minimize the adsorption of ammonia to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles, and additional ports for delivering ammonia-free background air and calibration gas standards. This instrument has been found to have a detection limit of 0.23 ppb at 1 Hz. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser Absorption Spectrometer (TDLAS during a laboratory intercomparison. The effect of humidity and heat on the surface interaction of ammonia with sample tubing was investigated at mixing ratios ranging from 30–1000 ppb. Humidity was seen to worsen the ammonia time response and considerable improvement was observed when using a heated sampling line. A field intercomparison of the QC-TILDAS with a modified Thermo 42CTL chemiluminescence based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE in the rural town of Egbert, ON between May–July 2008. Background tests and calibrations using two different permeation tube sources and an ammonia gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation with 1 min time resolution (R2=0.93 between the two instruments at the beginning of the study, when regular background

  9. Characterizing a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of atmospheric ammonia

    Directory of Open Access Journals (Sweden)

    R. A. Ellis

    2010-03-01

    Full Text Available A compact, fast-response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of ammonia (NH3 has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 0.5 L multiple pass absorption cell with an effective path length of 76 m. Detection is achieved using a thermoelectrically-cooled Mercury Cadmium Telluride (HgCdTe infrared detector. A novel sampling inlet was used, consisting of a short, heated, quartz tube with a hydrophobic coating to minimize the adsorption of NH3 to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles, and additional ports for delivering NH3-free background air and calibration gas standards. The level of noise in this instrument has been found to be 0.23 ppb at 1 Hz. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser Absorption Spectrometer (TDLAS during a laboratory intercomparison. The effect of humidity and heat on the surface interaction of NH3 with sample tubing was investigated at mixing ratios ranging from 30–1000 ppb. Humidity was seen to worsen the NH3 time response and considerable improvement was observed when using a heated sampling line. A field intercomparison of the QC-TILDAS with a modified Thermo 42CTL chemiluminescence-based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE in the rural town of Egbert, ON between May–July 2008. Background tests and calibrations using two different permeation tube sources and an NH3 gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation at 1 min time resolution (R2 = 0.93 between the two instruments at the

  10. Corsika+Herwig Monte Carlo Simulation of Neutrino Induced Atmospheric Air Showers

    CERN Document Server

    Ambrosio, M; Selva, A D; Miele, G; Pastor, S; Pisanti, O; Rosa, L

    2003-01-01

    High-energy neutrino astronomy represents an open window both on astrophysical mechanisms of particle acceleration and on fundamental interactions. The possibility of detecting them in large earth-based apparatus, like AUGER, AMANDA, ANTARES, is quite challenging. In view of this, the capability of generating reliable simulations of air showers induced by neutrinos is mandatory in the analysis of experimental data. In this paper we describe preliminary results towards the development of a new version of the Monte Carlo CORSIKA, capable of handling neutrinos too as primary particles. In our approach the first interaction of the primary neutrino is simulated in CORSIKA with a call to the HERWIG event generator.

  11. Experimental and theoretical determination of the efficiency of a sub-atmospheric flowing high power cascaded arc hydrogen plasma source

    NARCIS (Netherlands)

    Vijvers, W. A. J.; D.C. Schram,; Shumack, A. E.; Cardozo, N. J. L.; Rapp, J.; van Rooij, G. J.

    2010-01-01

    Cascaded arc plasma sources with channel diameters between 4 and 8mm were experimentally investigated at discharge currents up to 900A and hydrogen (H-2) flow rates up to 10 slm. Pressure measurements at the arc exit showed that the heavy particle temperature in the discharge channel was about 0.8 e

  12. Radio pulses from electromagnetic, hadronic and neutrino-induced showers up to EeV energies

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Muniz, Jaime, E-mail: jaime.alvarezmuniz@gmail.com [Depto. de Fisica de Particulas and Inst. Galego de Fisica de Altas Enerxias, Univ. de Santiago de Compostela, 15782 Santiago (Spain); Carvalho, Washington R.; Zas, Enrique [Depto. de Fisica de Particulas and Inst. Galego de Fisica de Altas Enerxias, Univ. de Santiago de Compostela, 15782 Santiago (Spain); Romero-Wolf, Andres [Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Tueros, Matias [Depto. de Fisica, Facultad de Ciencias Exactas, Univ. Nacional de La Plata (Argentina)

    2012-01-11

    The radio pulses emitted by electromagnetic, hadronic, and neutrino-induced showers are calculated for showers of energies in the EeV range and above in ice and in air. These are obtained in three-dimensional simulations of both the shower and the radio emission. An AIRES-based Monte Carlo code, ZHAIRES, has been developed for this purpose that allows us to predict the radio emission in both the time and frequency domains. The algorithms used, obtained from first principles, predict the radio emission due to all emission mechanisms, including the deflection of charged particles in the Earth's magnetic field. The code which has been extended to calculate in the Fresnel regime can reproduce the full complexity of the relevant shower phenomena.

  13. Neutrino-induced reactions and neutrino scattering with nuclei in low and high neutrino energy

    Science.gov (United States)

    Cheoun, Myung-Ki; Ha, Eunja; Yang, Ghil-Seok; Kim, K. S.; Kajino, T.

    2016-06-01

    We reviewed present status regarding theoretical approaches for neutrino-induced reactions and neutrino scattering. With a short introduction of relevant data, our recent calculations by distorted-wave Born approximation (DWBA) for quasielastic region are presented for MiniBooNE data. We also discussed that one step-process estimated by the DWBA is comparable to the two-step process, which has been usually used in the neutrino-nucleosynthesis. For much higher energy neutrino data, such as NOMAD data, elementary process approach was shown to be useful instead of using complicated nuclear models. But, in the low energy region, detailed nuclear structure model, such as QRPA and shell model, turn out to be inescapable to explain the reaction data.

  14. Atmospheric Deposition and Surface-Water Chemistry in Mount Rainier and North Cascades National Parks, U.S.A., Water Years 2000 and 2005-2006

    Science.gov (United States)

    Clow, David W.; Campbell, Donald H.

    2008-01-01

    High-elevation aquatic ecosystems in Mount Rainier and North Cascades National Parks are highly sensitive to atmospheric deposition of nitrogen and sulfur. Thin, rocky soils promote fast hydrologic flushing rates during snowmelt and rain events, limiting the ability of basins to neutralize acidity and assimilate nitrogen deposited from the atmosphere. Potential effects of nitrogen and sulfur deposition include episodic or chronic acidification of terrestrial and aquatic ecosystems. In addition, nitrogen deposition can cause eutrophication of water bodies and changes in species composition in lakes and streams. This report documents results of a study performed by the U.S. Geological Survey, in cooperation with the National Park Service, of the effects of atmospheric deposition of nitrogen and sulfur on surface-water chemistry in Mount Rainier and North Cascades National Parks. Inorganic nitrogen in wet deposition was highest in the vicinity of North Cascades National Park, perhaps due to emissions from human sources and activities in the Puget Sound area. Sulfur in wet deposition was highest near the Pacific coast, reflecting the influence of marine aerosols. Dry deposition generally accounted for less than 30 percent of wet plus dry inorganic nitrogen and sulfur deposition, but occult deposition (primarily fog) represents a potentially substantial unmeasured component of total deposition. Trend analyses indicate inorganic nitrogen in wet deposition was relatively stable during 1986-2005, but sulfur in wet deposition declined substantially during that time, particularly after 2001, when emissions controls were added to a large powerplant in western Washington. Surface-water sulfate concentrations at the study site nearest the powerplant showed a statistically significant decrease between 2000 and 2005-06, but there was no statistically significant change in alkalinity, indicating a delayed response in surface-water alkalinity. Seasonal patterns in surface

  15. Development of Miniaturized Difference Frequency Generation, Fiber Optic, and Quantum Cascade Laser Systems in Conjunction With Integrated Electronics for Global Studies of Atmospheric Tracers Using UAVs.

    Science.gov (United States)

    Witinski, M. F.; Lapson, L. B.; Anderson, J. G.

    2007-12-01

    In order to harness the power of UAVs (Unmanned Aerial Vehicles) for in situ atmospheric monitoring of tracers such as CO2, N2O, CH4, and H2O, we have developed small, lightweight, single mode laser systems with co- developed integrated electronics. The laser sources are of various types including newly developed cavity- enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a home-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electrical systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electrical components in achieving an apparatus that is compact, fully automated, and highly capable scientifically. Although the emphasis here is on atmospheric tracers, this technology could be applied to spectroscopic measurements of other atmospheric species such as isotopes, free radicals, and reactive intermediates.

  16. A Measurement of Neutrino-Induced Charged-Current Neutral Pion Production

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Robert H. [Univ. of Colorado, Boulder, CO (United States)

    2010-01-01

    This work presents the first comprehensive measurement of neutrino-induced charged-current neutral pion production (CCπ0) off a nuclear target. The Mini Booster Neutrino Experiment (MiniBooNE) and Booster Neutrino Beam (BNB) are discussed in detail. MiniBooNE is a high-statistics (~ 1, 000, 000 interactions) low-energy (Evϵ 2 0.5 - 2.0 GeV) neutrino experiment located at Fermilab. The method for selecting and reconstructing CCπ0 events is presented. The π0 and μ- are fully reconstructed in the final state allowing for the measurement of, among other things, the neutrino energy. The total observable CCπ0 cross-section is presented as a function of neutrino energy, along with five differential cross-sections in terms of the final state kinematics and Q2. The results are combined to yield a flux-averaged total cross-section of <σ>Φ = (9.2 ± 0.3stat. ± 1.5syst.) × 10-39 cm2/CH2 at energy 965 MeV. These measurements will aid future neutrino experiments with the prediction of their neutrino interaction rates.

  17. Simulation of up- and down-going neutrino induced showers at the site of the Pierre Auger Observatory

    CERN Document Server

    Gora, D; Tamburro, A; Gora, Dariusz; Roth, Markus; Tamburro, Alessio

    2006-01-01

    We present a study about the possibility to detect neutrino induced extensive air showers at the Pierre Auger Observatory. The Monte Carlo simulations performed take into account the details of the neutrino propagation inside the Earth, the air as well as the surrounding mountains which are modelled by a digital elevation map. Details on the sensitivity with respect to the incoming direction as well as the aperture and the total observable event rates are calculated on the basis of various assumptions of the incoming neutrino flux.

  18. A Search for Neutrino Induced Coherent NC($\\pi^{0}$) Production in the MINOS Near Detector

    Energy Technology Data Exchange (ETDEWEB)

    Cherdack, Daniel David [Tufts Univ., Medford, MA (United States)

    2011-02-01

    The production of single, highly forward π0 mesons by NC coherent neutrino-nucleus interactions (νμ + N → νμ + N + π0) is a process which probes fundamental aspects of the weak interaction. This reaction may also pose as a limiting background for long baseline searches for νμ → νe oscillations if the neutrino mixing angle θ13 is very small. The high-statistics sample of neutrino interactions recorded by the MINOS Near Detector provides an opportunity to measure the cross section of this coherent reaction on a relatively large-A nucleus at an average Ev = 4.9 GeV. A major challenge for this measurement is the isolation of forward-going electromagnetic (EM) showers produced by the relatively rare coherent NC(π0) process amidst an abundant rate of incoherently produced EM showers. The backgrounds arise from single π0 dominated NC events and also from quasi-elastic-like CC scattering of electron neutrinos. In this Thesis the theory of coherent interactions is summarized, and previous measurements of the coherent NC(π0) cross section are reviewed. Then, methods for selecting a sample of coherent NC(π0) like events, extracting the coherent NC(π0) event rate from that sample, estimating the analysis uncertainties, and calculating a cross section, are presented. A signal for neutrino-induced NC(π0) production is observed in the relevant kinematic regime as an excess of events of three standard deviations above background. The reaction cross sections, averaged over an energy window of 2.5 ≤ Ev ≤ 9.0 GeV is determined to be (31.6±10.5) x 10-40 cm2/nucleus. The result is the first evidence obtained for neutrino-nucleus coherent NC(π0) scattering on iron, and is the first measurement on an average nuclear target above A = 30. The cross section measurement

  19. Neutrino induced pion production at MiniBooNE and K2K within the GiBUU model

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, Tina; Buss, Oliver; Mosel, Ulrich [Institut fuer Theoretische Physik, Universitaet Giessen (Germany); Alvarez Ruso, Luis [Universidad de Murcia (Spain)

    2009-07-01

    The interest in neutrino nucleus reactions is driven by the discovery of neutrino oscillations where one now aims at a precise determination of neutrino oscillation parameters. This demands for an equally precise knowledge of the neutrino nucleus interaction process. Neutrino induced pion production is strongly influenced by nuclear effects. Their understanding is crucial since neutral current {pi}{sup 0} production is a major background in {nu}{sub e} appearance experiments, while charged current {pi}{sup +} production introduces a background to {nu}{sub {mu}} disappearance searches. We have investigated both, charged and neutral current neutrino induced pion production off nuclei, at MiniBooNE and K2K energies within the GiBUU transport model. Assuming impulse approximation, we treat the nucleus as a local Fermi gas of nucleons bound in a density and momentum potential. The outcome of the initial neutrino nucleon reaction undergoes complex hadronic final state interactions where in-medium spectral functions of the particles are taken into account. We present results for neutral current {pi}{sup 0} and charged current {pi}{sup +} production and compare to first MiniBooNE and K2K data.

  20. Continuous and high-precision atmospheric concentration measurements of COS, CO2, CO and H2O using a quantum cascade laser spectrometer (QCLS)

    Science.gov (United States)

    Kooijmans, Linda M. J.; Uitslag, Nelly A. M.; Zahniser, Mark S.; Nelson, David D.; Montzka, Stephen A.; Chen, Huilin

    2016-11-01

    Carbonyl sulfide (COS) has been suggested as a useful tracer for gross primary production as it is taken up by plants in a similar way as CO2. To explore and verify the application of this novel tracer, it is highly desired to develop the ability to perform continuous and high-precision in situ atmospheric measurements of COS and CO2. In this study we have tested a quantum cascade laser spectrometer (QCLS) for its suitability to obtain accurate and high-precision measurements of COS and CO2. The instrument is capable of simultaneously measuring COS, CO2, CO and H2O after including a weak CO absorption line in the extended wavelength range. An optimal background and calibration strategy was developed based on laboratory tests to ensure accurate field measurements. We have derived water vapor correction factors based on a set of laboratory experiments and found that for COS the interference associated with a water absorption line can dominate over the effect of dilution. This interference can be solved mathematically by fitting the COS spectral line separately from the H2O spectral line. Furthermore, we improved the temperature stability of the QCLS by isolating it in an enclosed box and actively cooling its electronics with the same thermoelectric chiller used to cool the laser. The QCLS was deployed at the Lutjewad atmospheric monitoring station (60 m; 6°21' E, 53°24' N; 1 m a.s.l.) in the Netherlands from July 2014 to April 2015. The QCLS measurements of independent working standards while deployed in the field showed a mean difference with the assigned cylinder value within 3.3 ppt COS, 0.05 ppm for CO2 and 1.7 ppb for CO over a period of 35 days. The different contributions to uncertainty in measurements of COS, CO2 and CO were summarized and the overall uncertainty was determined to be 7.5 ppt for COS, 0.23 ppm for CO2 and 3.3 ppb for CO for 1-minute data. A comparison of in situ QCLS measurements with those from concurrently filled flasks that were

  1. Neutrino induced weak pion production off the nucleon and coherent pion production in nuclei at low energies

    CERN Document Server

    Amaro, J E; Nieves, J; Valverde, M; Vicente-Vacas, M J

    2009-01-01

    We present a microscopic model for neutrino induced one-pion production off the nucleon and its implementation for the purpose of calculating coherent pion production in nuclei. We further criticize the use of the Rein--Sehgal model for coherent pion production by low energy neutrinos. In particular, we show how the approximations in that model give rise to a much flatter differential cross section in the $\\eta=E_\\pi(1-\\cos\\theta_\\pi)$ variable. We discuss the limitations intrinsic to any approach based on the partial conservation of the axial current hypothesis and the inability of such models to properly determine the angular distribution of the outgoing pion with respect to the direction of the incoming neutrino. We show the effects of those limitation for the case of the $\\frac{d\\sigma}{d\\eta}$ differential cross section.

  2. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  3. Search for neutrino-induced particle showers with IceCube-40

    DEFF Research Database (Denmark)

    Aartsen, M.G.; Abbasi, R.; Ackermann, M.;

    2014-01-01

    .L.) on the diffuse flux from astrophysical neutrinos of all neutrino flavors, applicable to the energy range 25 TeV to 5 PeV, assuming an E^−2 ν spectrum and a neutrino flavor ratio of 1:1:1 at the Earth. The third analysis utilized a larger and optimized sample of atmospheric muon background simulation, leading...

  4. Cascading Cosmology

    CERN Document Server

    Agarwal, Nishant; Khoury, Justin; Trodden, Mark

    2009-01-01

    We develop a fully covariant, well-posed 5D effective action for the 6D cascading gravity brane-world model, and use this to study cosmological solutions. We obtain this effective action through the 6D decoupling limit, in which an additional scalar degree mode, \\pi, called the brane-bending mode, determines the bulk-brane gravitational interaction. The 5D action obtained this way inherits from the sixth dimension an extra \\pi self-interaction kinetic term. We compute appropriate boundary terms, to supplement the 5D action, and hence derive fully covariant junction conditions and the 5D Einstein field equations. Using these, we derive the cosmological evolution induced on a 3-brane moving in a static bulk. We study the strong- and weak-coupling regimes analytically in this static ansatz, and perform a complete numerical analysis of our solution. Although the cascading model can generate an accelerating solution in which the \\pi field comes to dominate at late times, the presence of a critical singularity prev...

  5. Neutrino-induced Electroweak Symmetry Breaking in Supersymmetric SO(10) Unification

    CERN Document Server

    Inoue, K; Yoshioka, K; Inoue, Kenzo; Kojima, Kentaro; Yoshioka, Koichi

    2006-01-01

    The radiative electroweak symmetry breaking, the unification of third-generation Yukawa couplings, and flavor-changing rare decay are investigated in two types of supersymmetric SO(10) scenarios taking into account of the effects of neutrino physics, i.e. the observed large generation mixing and tiny mass scale. The first scenario is minimal, including right-handed neutrinos at intermediate scale with the unification of third-generation Yukawa couplings. Another is the case that the large mixing of atmospheric neutrinos originates from the charged-lepton sector. Under the SO(10)-motivated boundary conditions for supersymmetry-breaking parameters, typical low-energy particle spectrum is discussed and the parameter space is identified which satisfies the conditions for successful radiative electroweak symmetry breaking and the experimental mass bounds of superparticles. In particular, the predictions of the bottom quark mass and the b \\to s gamma branching ratio are fully analyzed. In both two scenarios, new ty...

  6. Influence of the photonuclear effect on electron-neutrino-induced electromagnetic cascades under the Landau-Pomeranchuk-Migdal regime in standard rock

    CERN Document Server

    Tartare, Mathieu; Montanet, François; 10.1103/PhysRevD.86.033005

    2012-01-01

    The observation of earth skimming neutrinos has been proposed as a rather sensitive method to detect ultra-high energy (UHE) cosmic neutrinos. Energetic cosmic neutrinos can interact inside the rock and produce leptons via a charged current interaction. In the case of an incoming electron neutrino undergoing a charged current interaction, the produced UHE electron will induce an underground electromagnetic shower. At high energy (above 7.7 TeV in standard rock), such showers are subject to LPM (Landau, Pomeranchuk and Migdal) suppression of the radiative processes cross sections (bremsstrahlung and pair production). The consequence of this suppression is that showers are elongated. This effect will increase the detection probability of such events allowing deeper showers to emerge with detectable energies. On the other hand, the photonuclear processes which are usually neglected in electromagnetic showers with respect to radiative processes, turn out to become dominant in the LPM regime and will reduce the sh...

  7. Isospin decomposition of the $\\gamma^{(*)} N \\to N^*$ transitions as input for constructing models of neutrino-induced reactions in the nucleon resonance region

    CERN Document Server

    Kamano, H; Lee, T -S H; Sato, T

    2016-01-01

    We present our recent efforts to determine the matrix elements associated with the transition between the nucleon and a nucleon resonance induced by the vector current, which are necessary ingredients for models of neutrino-induced reactions in the resonance region. This is accomplished by making the comprehensive analysis of the data for various meson photo- and electro-production reactions off the nucleon within a sophisticated coupled-channels framework, which is known as the ANL-Osaka dynamical coupled-channels model. We also give a brief introduction to our project for constructing a unified neutrino reaction model conducted at the J-PARC Branch of the KEK Theory Center.

  8. Atmospheric deposition, water-quality, and sediment data for selected lakes in Mount Rainer, North Cascades, and Olympic National Parks, Washington, 2008-10

    Science.gov (United States)

    Sheibley, Rich W.; Foreman, James R.; Moran, Patrick W.; Swarzenski, Peter W.

    2012-01-01

    To evaluate the potential effect from atmospheric deposition of nitrogen to high-elevation lakes, the U.S. Geological Survey partnered with the National Park Service to develop a "critical load" of nitrogen for sediment diatoms. A critical load is defined as the level of a given pollutant (in this case, nitrogen) at which detrimental effects to a target endpoint (sediment diatoms) result. Because sediment diatoms are considered one of the "first responders" to ecosystem changes from nitrogen, they are a sensitive indicator for nitrogen deposition changes in natural areas. This report presents atmospheric deposition, water quality, sediment geochronology, and sediment diatom data collected from July 2008 through August 2010 in support of this effort.

  9. Cascading costs: An economic nitrogen cycle

    Institute of Scientific and Technical Information of China (English)

    William R. Moomaw; Melissa B. L. Birch

    2005-01-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrifled to N2. We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single tonne of nitrogen can cascade through the system, the costs also cascade.Therefore evaluating the benefits of mitigating a tonne of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that tonne would cascade.The analysis reveals that it is most cost effective to remove a tonne of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  10. Measurement of the Atmospheric $\

    CERN Document Server

    Aartsen, M G; Abdou, Y; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohaichuk, S; Bohm, C; Bose1, D; Boser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clark, K; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; De Ridder, S; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Diaz-Velez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eberhardt, B; Eisch, J; Ellsworth, R W; Engdegard, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glusenkamp, T; Goldschmidt, A; Golup, G; Goodman, J A; Gora, D; Grant, D; Gross, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Klas, J; Klein, S R; Kohne, J -H; Kohnen, G; Kolanoski, H; Kopke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lunemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meszaros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Perez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Radel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schoneberg, S; Schonherr, L; Schonwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Sheremata, C; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stoss, A; Strahler, E A; Strom, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van der Drift, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge1, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zilles, A; Zoll, M

    2012-01-01

    We report the first observation in a high energy neutrino telescope of cascades induced by atmospheric electron neutrinos and by neutral current interactions of atmospheric neutrinos of all flavors. Using data recorded during the first year of operation of IceCube's DeepCore low energy extension, a sample of 1029 events is observed in 281 days of data. The number of observed cascades is $N_{\\rm cascade} = 496 \\pm 66 (stat.) \\pm 88(syst.)$ and the rest of the sample consists of residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is determined in the energy range between approximately 80 GeV and 6 TeV and is consistent with models of atmospheric neutrinos.

  11. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  12. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  13. Cascaded Poisson processes

    Science.gov (United States)

    Matsuo, Kuniaki; Saleh, Bahaa E. A.; Teich, Malvin Carl

    1982-12-01

    We investigate the counting statistics for stationary and nonstationary cascaded Poisson processes. A simple equation is obtained for the variance-to-mean ratio in the limit of long counting times. Explicit expressions for the forward-recurrence and inter-event-time probability density functions are also obtained. The results are expected to be of use in a number of areas of physics.

  14. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  15. A new cascadic multigrid

    Institute of Scientific and Technical Information of China (English)

    SHI; Zhongci

    2001-01-01

    [1]Bornemann, F., Deuflhard, P., The cascadic multigrid method for elliptic problems, Numer. Math., 996, 75: 35.[2]Bornemann, F., Deuflhard, P., The cascadic multigrid method, The Eighth International Conference on Domain Decomposition Methods for Partial Differential Equations (eds. Glowinski, R., Periaux, J., Shi, Z. et al.), New York: John Wiley and Sons, 997.[3]Bornemann, F., Krause, R., Classical and cascadic multigrid-methodogical comparison, Proceedings of the 9th International Conference on Domain Decomposition (eds. Bjorstad, P., Espedal, M., Keyes, D.), New York: John Wiley and Sons, 998.[4]Shaidurov, V., Some estimates of the rate of convergence for the cascadic conjugate gradient method, Comp. Math. Applic., 996, 3: 6.[5]Shi, Z., Xu, X., Cascadic multigrid method for the second order elliptic problem, East-West J. Numer. Math., 998, 6: 309.[6]Shi, Z., Xu, X., Cascadic multigrid for elliptic problems, East-West J. Numer. Math., 999, 7: 99.[7]Shi, Z., Xu, X., Cascadic multigrid method for the plate bending problem, East-West J. Numer. Math., 998, 6: 37.[8]Braess, D., Dahmen, W., A cascade multigrid algorithm for the Stokes equations, Number. Math., 999, 82: 79.[9]Shi, Z., Xu, X., Cascadic multigrid for parabolic problems, J. Comput. Math., 2000, 8: 450.[10]Ciarlet, P.,The Finite Element Method for Elliptic Problems, Amsterdam: North-Holland, 978.[11]Zienkiewicz, O. C., The Finite Element Method, 3rd. ed., London: McGraw-Hill, 977.[12]Powell, M. J. D., Sabin, M. A., Piecewise quadratic approximations on triangles, ACM Trans. Mat. Software, 977, 3: 36.[13]Xu, J., The auxiliary space method and optimal multigrid precondition techniques for unstructured grids, Computing, 996, 56: 25.[14]Bank, R., Dupont, T., An optimal order process for solving finite element equations, Math. Comput., 980, 36: 35.[15]Brenner, S., Convergence of nonconforming multigrid methods without full elliptic regularity, Math

  16. Information cascade on networks

    Science.gov (United States)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  17. Neutrino induced coherent pion production

    CERN Document Server

    Hernández, E; Valverde, M; Vicente-Vacas, M J

    2009-01-01

    We discuss different parameterizations of the $C_5^A(q^2)$ $N\\Delta$ axial form factor, fitted to the old Argonne bubble chamber data for pion production by neutrinos, and we use coherent pion production to test their low $q^2$ behavior. We find moderate effects that will be difficult to observe with the accuracy of present experiments. We also discuss the use of the Rein-Sehgal model for low energy coherent pion production. By comparison to a microscopic calculation, we show the weaknesses of some of the approximations in that model that lead to very large cross sections as well as to the wrong shapes for differential ones. Finally we show that models based on the partial conservation of the axial current hypothesis are not fully reliable for differential cross sections that depend on the angle formed by the pion and the incident neutrino.

  18. Period-doubling cascades galore

    OpenAIRE

    Sander, Evelyn; Yorke, James A.

    2009-01-01

    The appearance of numerous period-doubling cascades is among the most prominent features of {\\bf parametrized maps}, that is, smooth one-parameter families of maps $F:R \\times {\\mathfrak M} \\to {\\mathfrak M}$, where ${\\mathfrak M}$ is a smooth locally compact manifold without boundary, typically $R^N$. Each cascade has infinitely many period-doubling bifurcations, and it is typical to observe -- such as in all the examples we investigate here -- that whenever there are any cascades, there are...

  19. Inferring Network Structure from Cascades

    CERN Document Server

    Ghonge, Sushrut

    2016-01-01

    Many physical, biological and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we solve the dynamics of general cascade processes. We then offer three topological inversion methods to infer the structure of any directed network given a set of cascade arrival times. Our forward and inverse formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for 5 different cascade models.

  20. Measurement of the atmospheric v

    NARCIS (Netherlands)

    Adrián-Martínez, S.; van Haren, H.; ANTARES collaboration

    2013-01-01

    Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In this paper, a measurement of the atmospheric ?µ+?¯µ energy spectrum in the energy range 0.1–200 TeV is presented, using data collected by the ANTARES underwater neutrino telesc

  1. Information cascade on networks

    CERN Document Server

    Hisakado, Masato

    2015-01-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barab\\'{a}si-Albert(BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters--herders and independents--and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discussed the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade t...

  2. Energy Cascades in MHD

    Science.gov (United States)

    Alexakis, A.

    2009-04-01

    Most astrophysical and planetary systems e.g., solar convection and stellar winds, are in a turbulent state and coupled to magnetic fields. Understanding and quantifying the statistical properties of magneto-hydro-dynamic (MHD) turbulence is crucial to explain the involved physical processes. Although the phenomenological theory of hydro-dynamic (HD) turbulence has been verified up to small corrections, a similar statement cannot be made for MHD turbulence. Since the phenomenological description of Hydrodynamic turbulence by Kolmogorov in 1941 there have been many attempts to derive a similar description for turbulence in conducting fluids (i.e Magneto-Hydrodynamic turbulence). However such a description is going to be based inevitably on strong assumptions (typically borrowed from hydrodynamics) that do not however necessarily apply to the MHD case. In this talk I will discuss some of the properties and differences of the energy and helicity cascades in turbulent MHD and HD flows. The investigation is going to be based on the analysis of direct numerical simulations. The cascades in MHD turbulence appear to be a more non-local process (in scale space) than in Hydrodynamics. Some implications of these results to turbulent modeling will be discussed

  3. Cascade Distillation System Development

    Science.gov (United States)

    Callahan, Michael R.; Sargushingh, Miriam; Shull, Sarah

    2014-01-01

    NASA's Advanced Exploration Systems (AES) Life Support System (LSS) Project is chartered with de-veloping advanced life support systems that will ena-ble NASA human exploration beyond low Earth orbit (LEO). The goal of AES is to increase the affordabil-ity of long-duration life support missions, and to re-duce the risk associated with integrating and infusing new enabling technologies required to ensure mission success. Because of the robust nature of distillation systems, the AES LSS Project is pursuing develop-ment of the Cascade Distillation Subsystem (CDS) as part of its technology portfolio. Currently, the system is being developed into a flight forward Generation 2.0 design.

  4. Interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Weih, R.; Kamp, M.; Meyer, J. R.; Canedy, C. L.; Kim, C. S.; Kim, M.; Bewley, W. W.; Merritt, C. D.; Abell, J.; Höfling, S.

    2015-04-01

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron-hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3-6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm-2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT.

  5. Unsteady turbulence cascades

    Science.gov (United States)

    Goto, Susumu; Vassilicos, J. C.

    2016-11-01

    We have run a total of 311 direct numerical simulations (DNSs) of decaying three-dimensional Navier-Stokes turbulence in a periodic box with values of the Taylor length-based Reynolds number up to about 300 and an energy spectrum with a wide wave-number range of close to -5 /3 power-law dependence at the higher Reynolds numbers. On the basis of these runs, we have found a critical time when (i) the rate of change of the square of the integral length scale turns from increasing to decreasing, (ii) the ratio of interscale energy flux to high-pass filtered turbulence dissipation changes from decreasing to very slowly increasing in the inertial range, (iii) the signature of large-scale coherent structures disappears in the energy spectrum, and (iv) the scaling of the turbulence dissipation changes from the one recently discovered in DNSs of forced unsteady turbulence and in wind tunnel experiments of turbulent wakes and grid-generated turbulence to the classical scaling proposed by G. I. Taylor [Proc. R. Soc. London, Ser. A 151, 421 (1935), 10.1098/rspa.1935.0158] and A. N. Kolmogorov [Dokl. Akad. Nauk SSSR 31, 538 (1941)]. Even though the customary theoretical basis for this Taylor-Kolmogorov scaling is a statistically stationary cascade where large-scale energy flux balances dissipation, this is not the case throughout the entire time range of integration in all our DNS runs. The recently discovered dissipation scaling can be reformulated physically as a situation in which the dissipation rates of the small and large scales evolve together. We advance two hypotheses that may form the basis of a theoretical approach to unsteady turbulence cascades in the presence of large-scale coherent structures.

  6. Cascade Mountain Range in Oregon

    Science.gov (United States)

    Sherrod, David R.

    2016-01-01

    The Cascade mountain system extends from northern California to central British Columbia. In Oregon, it comprises the Cascade Range, which is 260 miles long and, at greatest breadth, 90 miles wide (fig. 1). Oregon’s Cascade Range covers roughly 17,000 square miles, or about 17 percent of the state, an area larger than each of the smallest nine of the fifty United States. The range is bounded on the east by U.S. Highways 97 and 197. On the west it reaches nearly to Interstate 5, forming the eastern margin of the Willamette Valley and, farther south, abutting the Coast Ranges. 

  7. Cascade Product of Permutation Groups

    OpenAIRE

    Egri-Nagy, Attila; Nehaniv, Chrystopher L.

    2013-01-01

    We define the cascade product of permutation groups as an external product, an explicit construction of substructures of the iterated wreath product that are much smaller than the full wreath product. This construction is essential for computational implementations of algebraic hierarchical decompositions of finite automata. We show how direct, semidirect, and wreath products and group extensions can all be expressed as cascade products, and analyse examples of groups that can be constructed ...

  8. Low Noise Interband Cascade Photodetectors

    Science.gov (United States)

    2012-02-28

    National Laboratories, Zhaobing Tian, Zhihua Cai, R. T. Hinkey, L. Li, Tetsuya D. Mishima , Michael B. Santos, and Matthew B. Johnson at the...Phys. 107, No. 5, 054514 (2010). 2. R. Q. Yang, Z. Tian, J. F. Klem, T. D. Mishima , M. B. Santos, and M. B. Johnson, “Interband cascade photovoltaic...2012). 4. Z. Tian, Z. Cai, R. Q. Yang, T. D. Mishima , M. B. Santos, M. B. Johnson, and J. F. Klem, “Interband Cascade Infrared Photodetectors

  9. Are longer cascades more stable?

    OpenAIRE

    2004-01-01

    Yes, they are. We consider data from experimental cascade games that were run in different laboratories, and find uniformly that subjects are more willing to follow the crowd, the bigger the crowd is �although the decision makers who are added to the crowd should in theory simply follow suit and hence reveal no information. This correlation of length and strength of cascades appears consistently across games with different parameters and different choice sets for the subjects. ...

  10. Aeroelasticity in Turbomachine-Cascades.

    Science.gov (United States)

    1982-11-10

    STABLE -180 UNSTABLE -360 ’ - ’ - -180 0. 󈧖O DIAGRAM 3 AERODYNAMIC LIFT (OENT)COEFFICIENTI AND PHASE LEADS IN DEPENDANCE OF FLOM GUANTATIES AND CASCADE...ABL -0.8 0.0 -5 0. -5 DIAGRAM ’. AERODYNAMIC NORK AND DAMPING COEFFICIENTS (FOR A RIGID NOTION) IN DEPENDANCE OF FLOW OURNTATIES AND CASCADE GEOMETRY...coefficients on blades + blade vibration + vizualization in the transonic flow domain (Schlieren) + instability dependance on flow conditions, blade

  11. Cascading Gravity is Ghost Free

    CERN Document Server

    de Rham, Claudia; Tolley, Andrew J

    2010-01-01

    We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.

  12. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  13. Communication Scheme via Cascade Chaotic Systems

    Institute of Scientific and Technical Information of China (English)

    HUA Chang-Chun; GUAN Xin-Ping

    2004-01-01

    @@ A new chaotic communication scheme is constructed. Different from the existing literature, cascade chaotic systems are employed. Two cascade modes are considered. First, we investigate the input to state cascade mode;cascade systems between different kinds of chaotic systems are considered. Then the parameter cascade case of chaotic system is studied. Under the different cases, the corresponding receivers are designed, which can succeed in recovering the former emitted signal. Simulations are performed to verify the validity of the proposed main results.

  14. Hadron cascade by the method of characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, K.H.; Portella, H.M.; Navia, C.E.; Shigueoka, H. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica]. E-mails: tsui@if.uff.br; hmport@if.uff.br; gficnoj@if.uff.br; hisa@if.uff.br; Oliveira, L.C.S. de [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: oliveira@cbpf.br

    2005-02-01

    Hadron diffusion equations with energy-dependent interaction mean free paths and inelasticities are solved using the Mellin transform. Instead of using operators on the finite difference terms, the Mellin transformed equations are Taylor expanded into a first order partial differential equation in atmospheric depth t and in the transform parameter s. Then, these equations are solved by the method of residues. For the case of a regularized power law primary spectrum these hadron fluxes are given by simple residues and one, never before mentioned, essential singularities. A comparison of our solutions with the nucleon flux measured at sea level and with the hadron fluxes measured at t = 840 g/cm{sup 2} and at sea level are made. The agreement between them is in general very good, greater than 90%. In order to check the accuracy of our calculations, a comparison between our solution and the simulated nucleon cascades is also made. (author)

  15. Cascaded-cladding-pumped cascaded Raman fiber amplifier.

    Science.gov (United States)

    Jiang, Huawei; Zhang, Lei; Feng, Yan

    2015-06-01

    The conversion efficiency of double-clad Raman fiber laser is limited by the cladding-to-core area ratio. To get high conversion efficiency, the inner-cladding-to-core area ratio has to be less than about 8, which limits the brightness enhancement. To overcome the problem, a cascaded-cladding-pumped cascaded Raman fiber laser with multiple-clad fiber as the Raman gain medium is proposed. A theoretical model of Raman fiber amplifier with multiple-clad fiber is developed, and numerical simulation proves that the proposed scheme can improve the conversion efficiency and brightness enhancement of cladding pumped Raman fiber laser.

  16. Autoregressive cascades on random networks

    Science.gov (United States)

    Iyer, Srikanth K.; Vaze, Rahul; Narasimha, Dheeraj

    2016-04-01

    A network cascade model that captures many real-life correlated node failures in large networks via load redistribution is studied. The considered model is well suited for networks where physical quantities are transmitted, e.g., studying large scale outages in electrical power grids, gridlocks in road networks, and connectivity breakdown in communication networks, etc. For this model, a phase transition is established, i.e., existence of critical thresholds above or below which a small number of node failures lead to a global cascade of network failures or not. Theoretical bounds are obtained for the phase transition on the critical capacity parameter that determines the threshold above and below which cascade appears or disappears, respectively, that are shown to closely follow numerical simulation results.

  17. Finite-size scaling of two-point statistics and the turbulent energy cascade generators.

    Science.gov (United States)

    Cleve, Jochen; Dziekan, Thomas; Schmiegel, Jürgen; Barndorff-Nielsen, Ole E; Pearson, Bruce R; Sreenivasan, Katepalli R; Greiner, Martin

    2005-02-01

    Within the framework of random multiplicative energy cascade models of fully developed turbulence, finite-size-scaling expressions for two-point correlators and cumulants are derived, taking into account the observationally unavoidable conversion from an ultrametric to an Euclidean two-point distance. The comparison with two-point statistics of the surrogate energy dissipation, extracted from various wind tunnel and atmospheric boundary layer records, allows an accurate deduction of multiscaling exponents and cumulants, even at moderate Reynolds numbers for which simple power-law fits are not feasible. The extracted exponents serve as input for parametric estimates of the probabilistic cascade generator. Various cascade generators are evaluated.

  18. Comparative Analyses of Brookhaven National Laboratory Nuclear Decay Measurements and Super-Kamiokande Solar Neutrino Measurements: Neutrinos and Neutrino-Induced Beta-Decays as Probes of the Deep Solar Interior

    Science.gov (United States)

    Sturrock, P. A.; Fischbach, E.; Scargle, J. D.

    2016-12-01

    An experiment carried out at the Brookhaven National Laboratory over a period of almost 8 years acquired 364 measurements of the beta-decay rates of a sample of {}^{32}Si and, for comparison, of a sample of {}^{36}Cl. The experimenters reported finding " small periodic annual deviations of the data points from an exponential decay … of uncertain origin". We find that power-spectrum and spectrogram analyses of these datasets show evidence not only of the annual oscillations, but also of transient oscillations with frequencies near 11 year-1 and 12.5 year-1. Similar analyses of 358 measurements of the solar neutrino flux acquired by the Super-Kamiokande neutrino observatory over a period of about 5 years yield evidence of an oscillation near 12.5 year-1 and another near 9.5 year-1. An oscillation near 12.5 year-1 is compatible with the influence of rotation of the radiative zone. We suggest that an oscillation near 9.5 year-1 may be indicative of rotation of the solar core, and that an oscillation near 11 year-1 may have its origin in a tachocline between the core and the radiative zone. Modulation of the solar neutrino flux may be attributed to an influence of the Sun's internal magnetic field by the Resonant Spin Flavor Precession (RSFP) mechanism, suggesting that neutrinos and neutrino-induced beta decays can provide information about the deep solar interior.

  19. Unsteady transonic flow in cascades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1984-01-01

    There is a need for methods to predict the unsteady air loads associated with flutter of turbomachinery blading at transonic speeds. The results of such an analysis in which the steady relative flow approaching a cascade of thin airfoils is assumed to be transonic, irrotational, and isentropic is presented. The blades in the cascade are allowed to undergo a small amplitude harmonic oscillation which generates a small unsteady flow superimposed on the existing steady flow. The blades are assumed to oscillate with a prescribed motion of constant amplitude and interblade phase angle. The equations of motion are obtained by linearizing about a uniform flow the inviscid nonheat conducting continuity and momentum equations. The resulting equations are solved by employing the Weiner Hopf technique. The solution yields the unsteady aerodynamic forces acting on the cascade at Mach number equal to 1. Making use of an unsteady transonic similarity law, these results are compared with the results obtained from linear unsteady subsonic and supersonic cascade theories. A parametric study is conducted to find the effects of reduced frequency, solidity, stagger angle, and position of pitching axis on the flutter.

  20. Azobenzene-functionalized cascade molecules

    DEFF Research Database (Denmark)

    Archut, A.; Vogtle, F.; De Cola, L.;

    1998-01-01

    Cascade molecules bearing up to 32 azobenzene groups in the periphery have been prepared from poly(propylene imine) dendrimers and N-hydroxysuccinimide esters. The dendritic azobenzene species show similar isomerization properties as the corresponding azobenzene monomers. The all-E azobenzene...

  1. CASCADE: Introducing AI into CBT.

    Science.gov (United States)

    Hendley, R. J.; Jurascheck, N.

    1992-01-01

    Discusses changes in training requirements of commerce and industry in the United Kingdom and describes a project, CASCADE, that was developed to investigate and implement the introduction of artificial intelligence (AI) techniques into computer-based training (CBT). An overview of pilot projects in higher education settings is provided. (eight…

  2. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.

  3. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.

  4. Cascade Support Vector Machines with Dimensionality Reduction

    Directory of Open Access Journals (Sweden)

    Oliver Kramer

    2015-01-01

    Full Text Available Cascade support vector machines have been introduced as extension of classic support vector machines that allow a fast training on large data sets. In this work, we combine cascade support vector machines with dimensionality reduction based preprocessing. The cascade principle allows fast learning based on the division of the training set into subsets and the union of cascade learning results based on support vectors in each cascade level. The combination with dimensionality reduction as preprocessing results in a significant speedup, often without loss of classifier accuracies, while considering the high-dimensional pendants of the low-dimensional support vectors in each new cascade level. We analyze and compare various instantiations of dimensionality reduction preprocessing and cascade SVMs with principal component analysis, locally linear embedding, and isometric mapping. The experimental analysis on various artificial and real-world benchmark problems includes various cascade specific parameters like intermediate training set sizes and dimensionalities.

  5. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  6. Bankruptcy Cascades in Interbank Markets

    Science.gov (United States)

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  7. Thermal cascaded lattice Boltzmann method

    CERN Document Server

    Fei, Linlin

    2016-01-01

    In this paper, a thermal cascaded lattice Boltzmann method (TCLBM) is developed in combination with the double-distribution-function (DDF) approach. A density distribution function relaxed by the cascaded scheme is employed to solve the flow field, and a total energy distribution function relaxed by the BGK scheme is used to solve temperature field, where two distribution functions are coupled naturally. The forcing terms are incorporated by means of central moments, which is consistent with the previous force scheme [Premnath \\emph{et al.}, Phys. Rev. E \\textbf{80}, 036702 (2009)] but the derivation is more intelligible and the evolution process is simpler. In the method, the viscous heat dissipation and compression work are taken into account, the Prandtl number and specific-heat ratio are adjustable, the external force is considered directly without the Boussinesq assumption, and the low-Mach number compressible flows can also be simulated. The forcing scheme is tested by simulating a steady Taylor-Green f...

  8. Cascade Chaotic System With Applications.

    Science.gov (United States)

    Zhou, Yicong; Hua, Zhongyun; Pun, Chi-Man; Chen, C L Philip

    2015-09-01

    Chaotic maps are widely used in different applications. Motivated by the cascade structure in electronic circuits, this paper introduces a general chaotic framework called the cascade chaotic system (CCS). Using two 1-D chaotic maps as seed maps, CCS is able to generate a huge number of new chaotic maps. Examples and evaluations show the CCS's robustness. Compared with corresponding seed maps, newly generated chaotic maps are more unpredictable and have better chaotic performance, more parameters, and complex chaotic properties. To investigate applications of CCS, we introduce a pseudo-random number generator (PRNG) and a data encryption system using a chaotic map generated by CCS. Simulation and analysis demonstrate that the proposed PRNG has high quality of randomness and that the data encryption system is able to protect different types of data with a high-security level.

  9. Optimally Training a Cascade Classifier

    CERN Document Server

    Shen, Chunhua; Hengel, Anton van den

    2010-01-01

    Cascade classifiers are widely used in real-time object detection. Different from conventional classifiers that are designed for a low overall classification error rate, a classifier in each node of the cascade is required to achieve an extremely high detection rate and moderate false positive rate. Although there are a few reported methods addressing this requirement in the context of object detection, there is no a principled feature selection method that explicitly takes into account this asymmetric node learning objective. We provide such an algorithm here. We show a special case of the biased minimax probability machine has the same formulation as the linear asymmetric classifier (LAC) of \\cite{wu2005linear}. We then design a new boosting algorithm that directly optimizes the cost function of LAC. The resulting totally-corrective boosting algorithm is implemented by the column generation technique in convex optimization. Experimental results on object detection verify the effectiveness of the proposed bo...

  10. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  11. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  12. Control of Cascaded Multilevel Inverters

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Abstract-A new type of multilevel inverter is introduced which is created by cascading two three-phase three-level inverters using the load connection, but requires only one DC voltage source. This new inverter can operateas a seven-level inverter and naturally splits the power conversion into a higher-voltage lower-frequency inverter and a lower-voltage higher-fre-quency inverter. This type of system presents particular advantages to Naval ship propulsion systems which rely on high power quality, survivable drives. New control methods are described involving both joint and separate control of the individual three-level inverters. Simulation resuits demonstrate the effectiveness of both controls. A laboratory set-up at the Naval Surface Warfare Center power electronics laboratory was used to validate the proposed joint-inverter control. Due to the effect of compounding levels in the cascaded inverter, a high number of levels are available resulting in a voltage THD of 9% (without filtering). Index Terms-Cascaded inverter, multilevel inverter, three-level inverter.

  13. Turbulence: does energy cascade exist?

    CERN Document Server

    Josserand, Christophe; Lehner, Thierry; Pomeau, Yves

    2016-01-01

    To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These tests are applied to real Eulerian data of a turbulent velocity flow, taken in the wind grid tunnel of Modane, and also to a prototype model equation for wave turbulence. First we demonstrate the irreversible character of the flow by using multi-time correlation function at a given point of space. Moreover the unexpected behavior of the test function leads us to connect irreversibility and finite time singularities (intermittency). Secondly we show that turbulent cascade exists, and is a dynamical process, by using a test function depending on time and frequency. The cascade shows up only in the inertial domain where the kinetic energy is transferred more rapidly (on average) from the wavenumber $k_{1}$ to $k_{2}$ than from $k_{1}$ to $k'_{2}$ larger than $k_{2}$.

  14. Energy cascades in the upper ocean

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Scott Chubb

    2006-01-01

    Wave-wave interactions cause energy cascades. These are the most important processes in the upper ocean because they govern wave-growth and dissipation. Through indirect cascades, wave energy is transferred from higher frequencies to lower frequencies, leading to wave growth. In direct cascades, energy is transferred from lower frequencies to the higher frequencies, which causes waves to break, and dissipation of wave energy. However, the evolution and origin of energy cascade processes are still not fully understood. In particular, for example, results from a recent theory (Kalmykov, 1998) suggest that the class I wave-wave interactions (defined by situations involving 4-, 6-, 8-, etc, even numbers of resonantly interacting waves) cause indirect cascades, and Class II wave-wave interactions (involving, 5-, 7-, 9-, etc, .., odd numbers of waves) cause direct cascades. In contrast to this theory, our model results indicate the 4-wave interactions can cause significant transfer of wave energy through both direct and indirect cascades. In most situations, 4-wave interactions provide the major source of energy transfer for both direct cascades and indirect cascades, except when the wave steepness is larger than 0.28. Our model results agree well with wave measurements, obtained using field buoy data (for example, Lin and Lin, 2002). In particular, in these observations, asymmetrical wave-wave interactions were studied. They found that direct and indirect cascades both are mainly due to the 4-wave interactions when wave steepness is less than 0.3.

  15. A Comparison of Methods for Cascade Prediction

    CERN Document Server

    Guo, Ruocheng

    2016-01-01

    Information cascades exist in a wide variety of platforms on Internet. A very important real-world problem is to identify which information cascades can go viral. A system addressing this problem can be used in a variety of applications including public health, marketing and counter-terrorism. As a cascade can be considered as compound of the social network and the time series. However, in related literature where methods for solving the cascade prediction problem were proposed, the experimental settings were often limited to only a single metric for a specific problem formulation. Moreover, little attention was paid to the run time of those methods. In this paper, we first formulate the cascade prediction problem as both classification and regression. Then we compare three categories of cascade prediction methods: centrality based, feature based and point process based. We carry out the comparison through evaluation of the methods by both accuracy metrics and run time. The results show that feature based met...

  16. Spray formation: an inverse cascade

    CERN Document Server

    Ling, Yue; Tryggvason, Gretar; zaleski, Stephane

    2015-01-01

    We present a study of droplet formation in a gas-liquid mixing layer using direct numerical simulation. It is seen that two mechanisms compete to generate the droplets: fingering at the tip of the waves and hole formation in the thin liquid sheet. The three dimensional liquid structures are much shorter than the longitudinal wavelength of the instability at the first instant of their formation. As time evolves, the structures evolves to larger and larger scales, in a way similar to the inverse cascade of length scales in droplet impact and impact crown formation.

  17. Disaster Mythology and Availability Cascades

    Directory of Open Access Journals (Sweden)

    Lisa Grow Sun

    2013-04-01

    Full Text Available Sociological research conducted in the aftermath of natural disasters has uncovered a number of “disaster myths” – widely shared misconceptions about typical post-disaster human behavior. This paper discusses the possibility that perpetuation of disaster mythology reflects an “availability cascade,” defined in prior scholarship as a “self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse.” (Kuran and Sunstein 1999. Framing the spread of disaster mythology as an availability cascade suggests that certain tools may be useful in halting the myths’ continued perpetuation. These tools include changing the legal and social incentives of so-called “availability entrepreneurs” – those principally responsible for beginning and perpetuating the cascade, as well as insulating decision-makers from political pressures generated by the availability cascade. This paper evaluates the potential effectiveness of these and other solutions for countering disaster mythology. Las investigaciones sociológicas realizadas tras los desastres naturales han hecho evidentes una serie de “mitos del desastre”, conceptos erróneos ampliamente compartidos sobre el comportamiento humano típico tras un desastre. Este artículo analiza la posibilidad de que la perpetuación de los mitos del desastre refleje una “cascada de disponibilidad”, definida en estudios anteriores como un “proceso de auto-refuerzo de la formación de una creencia colectiva, a través del que una percepción expresada produce una reacción en cadena que hace que la percepción sea cada vez más verosímil, a través de una mayor presencia en el discurso público” (Kuran y Sunstein 1999. Enmarcar la propagación de los mitos del desastre como una cascada de disponibilidad sugiere que ciertas herramientas pueden ser

  18. Cascades on clique-based graphs

    CERN Document Server

    Hackett, Adam

    2013-01-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly-clustered random graphs introduced in [J. P. Gleeson, Phys. Rev. E 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  19. Lateral Modes in Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Gregory C. Dente

    2016-03-01

    Full Text Available We will examine the waveguide mode losses in ridge-guided quantum cascade lasers. Our analysis illustrates how the low-loss mode for broad-ridge quantum cascade lasers (QCLs can be a higher-order lateral waveguide mode that maximizes the feedback from the sloped ridge-wall regions. The results are in excellent agreement with the near- and far-field data taken on broad-ridge-guided quantum cascade lasers processed with sloped ridge walls.

  20. WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ouliang [Oracle Corporation, Redwood Shores, CA (United States); Gary, S. Peter [Space Science Institute, Boulder, CO (United States); Wang, Joseph, E-mail: ouliang@usc.edu, E-mail: pgary@lanl.gov, E-mail: josephjw@usc.edu [University of Southern California, Los Angeles, CA (United States)

    2015-02-20

    We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime.

  1. Unsteady transonic flow over cascade blades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1986-01-01

    An attempt is made to develop an efficient staggered cascade blade unsteady aerodynamics model for the neighborhood of March 1, representing the blade row by a rectilinear two-dimensional cascade of thin, flat plate airfoils. The equations of motion are derived on the basis of linearized transonic small perturbation theory, and an analytical solution is obtained by means of the Wiener-Hopf procedure. Making use of the transonic similarity law, the results obtained are compared with those of other linearized cascade analyses. A parametric study is conducted to find the effects of reduced frequency, stagger angle, solidity, and the location of the pitching axis on cascade stability.

  2. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  3. Single-Seed Cascades on Clustered Networks

    CERN Document Server

    McSweeney, John K

    2015-01-01

    We consider a dynamic network cascade process developed by Watts applied to a random networks with a specified amount of clustering, belonging to a class of random networks developed by Newman. We adapt existing tree-based methods to formulate an appropriate two-type branching process to describe the spread of a cascade started with a single active node, and obtain a fixed-point equation to implicitly express the extinction probability of such a cascade. In so doing, we also recover a special case of a formula of Hackett et al. giving conditions for certain extinction of the cascade.

  4. Multifunctional Cascaded Metamaterials: Integrated Transmitarrays

    Science.gov (United States)

    Elsakka, Amr A.; Asadchy, Viktar S.; Faniayeu, Ihar A.; Tcvetkova, Svetlana N.; Tretyakov, Sergei A.

    2016-10-01

    Control of electromagnetic waves using engineered materials is very important in a wide range of applications, therefore there is always a continuous need for new and more efficient solutions. Known natural and artificial materials and surfaces provide a particular functionality in the frequency range they operate but cast a "shadow" and produce reflections at other frequencies. Here, we introduce a concept of multifunctional engineered materials that possess different predetermined functionalities at different frequencies. Such response can be accomplished by cascading metasurfaces (thin composite layers) that are designed to perform a single operation at the desired frequency and are transparent elsewhere. Previously, out-of-band transparent metasurfaces for control over reflection and absorption were proposed. In this paper, to complete the full set of functionalities for wave control, we synthesize transmitarrays that tailor transmission in a desired way, being "invisible" beyond the operational band. The designed transmitarrays for wavefront shaping and anomalous refraction are tested numerically and experimentally. To demonstrate our concept of multifunctional engineered materials, we have designed a cascade of three metasurfaces that performs three different functions for waves at different frequencies. Remarkably, applied to volumetric metamaterials, our concept can enable a single composite possessing desired multifunctional response.

  5. Time evolution of cascade decay

    CERN Document Server

    Boyanovsky, Daniel

    2014-01-01

    We study non-perturbatively the time evolution of cascade decay for generic fields $\\pi \\rightarrow \\phi_1\\phi_2\\rightarrow \\phi_2\\chi_1\\chi_2$ and obtain the time dependence of amplitudes and populations for the resonant and final states. We analyze in detail the different time scales and the manifestation of unitary time evolution in the dynamics of production and decay of resonant intermediate and final states. The probability of occupation (population) ``flows'' as a function of time from the initial to the final states. When the decay width of the parent particle $\\Gamma_\\pi$ is much larger than that of the intermediate resonant state $\\Gamma_{\\phi_1}$ there is a ``bottleneck'' in the flow, the population of resonant states builds up to a maximum at $t^* = \\ln[\\Gamma_\\pi/\\Gamma_{\\phi_1}]/(\\Gamma_\\pi-\\Gamma_{\\phi_1})$ nearly saturating unitarity and decays to the final state on the longer time scale $1/\\Gamma_{\\phi_1}$. As a consequence of the wide separation of time scales in this case the cascade decay ...

  6. Direct and Inverse Cascades in the Acceleration Region of the Fast Solar Wind

    Science.gov (United States)

    van Ballegooijen, A. A.; Asgari-Targhi, M.

    2017-01-01

    Alfvén waves are believed to play an important role in the heating and acceleration of the fast solar wind emanating from coronal holes. Nonlinear interactions between the dominant {{\\boldsymbol{z}}}+ waves and minority {{\\boldsymbol{z}}}- waves have the potential to transfer wave energy either to smaller perpendicular scales (“direct cascade”) or to larger scales (“inverse cascade”). In this paper we use reduced magnetohydrodynamic (RMHD) simulations to investigate how the cascade rates {ε }+/- depend on perpendicular wavenumber and radial distance from the Sun center. For models with a smooth background atmosphere, we find that an inverse cascade ({ε }+ 0) occurs elsewhere. For a model with density fluctuations, there are multiple regions with an inverse cascade. In both cases, the cascade rate {ε }+ varies significantly with perpendicular wavenumber, indicating that the cacsade is a highly nonlocal process. As a result of the inverse cascades, the energy dissipation rates are much lower than expected from a phenomenological model and are insufficient to maintain the temperature of the background atmosphere. We conclude that RMHD models are unable to reproduce the observed properties of the fast solar wind.

  7. DISTURBANCE ATTENUATION FOR UNCERTAIN NONLINEAR CASCADED SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    BI Weiping; MU Xiaowu; SUN Yuqiang

    2004-01-01

    In present paper, the disturbance attenuation problem of uncertain nonlinear cascaded systems is studied. Based on the adding one power integrator technique and recursive design, a feedback controller that solves the disturbance attenuation problem is constructed for uncertain nonlinear cascaded systems with internal stability.

  8. Cascade Harvest’ red raspberry

    Science.gov (United States)

    Cascade Harvest’ is a new floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). ‘Cascade Harvest’ produces a high yield of large, firm fruit suited to machine harves...

  9. A NOTE ON VECTOR CASCADE ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Qiu-hui Chen; Jin-zhao Liu; Wen-sheng Zhang

    2002-01-01

    The focus of this paper is on the relationship between accuracy of multivariate refinable vector and vector cascade algorithm. We show that, if the vector cascade algorithm (1.5) with isotropic dilation converges to a vector-valued function with regularity, then the initial function must satisfy the Strang-Fix conditions.

  10. Multifunctional Cascaded Metamaterials: Integrated Transmitarrays

    CERN Document Server

    Elsakka, Amr A; Faniayeu, Ihar A; Tcvetkova, Svetlana N; Tretyakov, Sergei A

    2016-01-01

    Control of electromagnetic waves using engineered materials is very important in a wide range of applications, therefore there is always a continuous need for new and more efficient solutions. Known natural and artificial materials and surfaces provide a particular functionality in the frequency range they operate but cast a "shadow" and produce reflections at other frequencies. Here, we introduce a concept of multifunctional engineered materials that possess different predetermined functionalities at different frequencies. Such response can be accomplished by cascading metasurfaces (thin composite layers) that are designed to perform a single operation at the desired frequency and are transparent elsewhere. Previously, out-of-band transparent metasurfaces for control over reflection and absorption were proposed. In this paper, to complete the full set of functionalities for wave control, we synthesize transmitarrays that tailor transmission in a desired way, being "invisible" beyond the operational band. The...

  11. Network reconstruction from infection cascades

    CERN Document Server

    Braunstein, Alfredo

    2016-01-01

    Reconstructing propagation networks from observations is a fundamental inverse problem, and it's crucial to understand and control dynamics in complex systems. Here we show that it is possible to reconstruct the whole structure of an interaction network and to simultaneously infer the complete time course of activation spreading, relying just on single snapshots of a small number of activity cascades. The method, that we called Inverse Dynamics Network Reconstruction (IDNR), is shown to work successfully on several synthetic and real networks, inferring the networks and the sources of infection based on sparse observations, including single snapshots. IDNR is built on a Belief Propagation approximation, that has an impressive performance in a wide variety of topological structures. The method can be applied in absence of complete time-series data by providing a detailed modeling of the posterior distribution of trajectories conditioned to the observations. Furthermore, we show by experiments that the informat...

  12. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2015-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  13. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2014-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  14. Cascades in interdependent flow networks

    CERN Document Server

    Scala, Antonio; Caldarelli, Guido; D'Agostino, Gregorio

    2015-01-01

    We investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  15. MAPK Cascades in Guard Cell Signal Transduction

    Science.gov (United States)

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M.

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions. PMID:26904052

  16. MAPK cascades in guard cell signal transduction

    Directory of Open Access Journals (Sweden)

    Yuree eLee

    2016-02-01

    Full Text Available Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

  17. Check of the accuracy of the relativity theory with atmospheric muon neutrinos from the AMANDA data of the years 2000 to 2003; Ueberpruefung der Genauigkeit der Relativitaetstheorie mit atmosphaerischen Myonneutrinos aus den AMANDA-Daten der Jahre 2000 bis 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ahrens, J.C.

    2006-11-08

    Atmospheric neutrinos allow one to test the principles of the Theory of Relativity in particular Lorentz invariance and the equivalence principle. Small deviations from these principles could lead, according to some theories, to detectable neutrino oscillations. Such oscillation effects are analysed in this thesis, using the data collected by the AMANDA detector. The neutrino telescope AMANDA is located at the South Pole and embedded in the Antarctic ice shield at a depth between 1500 m and 2000 m. AMANDA detects muon neutrinos via the Cherenkov light of neutrino induced muons allowing the reconstruction of the original neutrino direction. From the data of the years 2000 to 2003, which contain about seven billion recorded events and which mainly consist of the background of atmospheric muons, a sample of 3401 neutrino induced events has been selected. No indication for alternative oscillation effects has been found. For maximal mixing angles, a lower limit for parameters which violate Lorentz invariance or the equivalence principle could be set to {delta}{beta}(2 vertical stroke {phi} vertical stroke {delta}{gamma}){<=}5.15.10{sup -27}. (orig)

  18. Neutrino induced showering from the Earth

    CERN Document Server

    Fargion, D

    2003-01-01

    Ultra High Energy, UHE, Neutrino Astronomy should be soon tested looking toward the Earth. At present High Energy Neutrino Astronomy is searched by AMANDA, ANTARES underground detectors looking for its consequent unique muons secondary track. We suggest a higher energy Tau Neutrino Astronomy based on Horizontal and Upward Tau Air-Showers escaping from the Earth. These Tau air-showers greatly amplifies the single tau track by an abundant secondary tail (billions of electron pairs, gamma and tens of millions muon bundles) spread in huge areas (kilometer size) easily observable (even partially) from high mountains, balloon or satellite array detectors. Possible early evidence of such a New Neutrino UPTAUs or HORTAUs (Upward or Horizontal Tau Air-Showers) Astronomy may be already found in rare BATSE gamma records of brief up-going gamma showers named Terrestrial Gamma Flashes (TGF). The TGF features, energy and arrival clustering are well tuned to upward tau air-showers. Future confirmation of the Neutrino Tau As...

  19. A NEUTRINO INDUCED FOUR LEPTON EVENT

    Energy Technology Data Exchange (ETDEWEB)

    Loveless, R. J. [Department of Physics, University of Wisconsin, Madison, WI; Benada, R. [Department of Physics, University of Wisconsin, Madison, WI; Duffy, M. [Department of Physics, University of Wisconsin, Madison, WI; Fry, W. [Department of Physics, University of Wisconsin, Madison, WI; McCabe, P. [Department of Physics, University of Wisconsin, Madison, WI; Minette, D. [Department of Physics, University of Wisconsin, Madison, WI; Ngai, D. [Department of Physics, University of Wisconsin, Madison, WI; Reeder, D. D. [Department of Physics, University of Wisconsin, Madison, WI; Ballagh, H. C. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Bingham, H H [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Fretter, W. B. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Lawry, T. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Lynch, G. R. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Lys, J. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Marriner, J. P. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Orthel, J. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Stevenson, M. L. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Sokoloff, M. D. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; Yost, G. P. [Department of Physics and Lawrence Berkeley Lab, University of California Berkeley, CA; et al.,

    1978-05-01

    We report observation of a neutrino (antineutrino)-induced event with two electrons, one positron, one positively charged muon, a neutral K meson, and seven gammas in an experiment performed in the FNAL 15-ft. bubble chamber with a 47% atomic mixture of neon in hydrogen. Estimated experimental electron backgrounds are ~10⁻⁴ per track. At present we have no plausible interpretation of this event.

  20. Neutrino induced magnetic moment and spin precession

    Science.gov (United States)

    Ternov, A. I.

    2016-07-01

    When propagating through a dispersing medium, a massive neutrino acquires an induced magnetic moment that may give rise to a helicity flip in an external magnetic field with a larger probability than that caused by the anomalous magnetic moment. This phenomenon is investigated in the framework of relativistic quantum mechanics and of the generalized Bargmann-Michel-Telegdi equation.

  1. Neutrino induced events in the MINOS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Litchfield, Reuben Phillip [Univ. of Oxford (United Kingdom). Keble College

    2008-01-01

    The MINOS experiment is designed to study neutrino oscillations. It uses an accelerator generated beam of neutrinos and two detectors, the smaller at a distance of 1km and the larger at 735 km. By comparing the spectrum and flavour composition of the beam at the two detectors precise determinations of the oscillation parameters are possible. This thesis concentrates on the analysis of data from the larger Far Detector. By studying the spectrum of neutral current events it is possible to look for evidence of non-interacting 'sterile' neutrinos. The thesis describes how events are selected for this analysis, and a method for discriminating between charged current and neutral current events. The systematic uncertainties resulting from these cuts are evaluated. Several techniques for using Near Detector data to eliminate systematic uncertainties in the predicted Far Detector spectrum are compared. An oscillation analysis, based on the first year of MINOS data, uses the selected events to make a measurement of f{sub s}, the fraction of unseen neutrinos that are sterile. The measured value is fs = 0.07+0.32 at 68%C.L., and is consistent with the standard three-neutrino picture, which has no sterile neutrino.

  2. Quantitative x-ray diffraction phase analysis of coarse airborne particulate collected by cascade impactor sampling

    Science.gov (United States)

    Esteve, V.; Rius, J.; Ochando, L. E.; Amigó, J. M.

    Mineralogical composition of Castellon (Spanish Mediterranean coast) atmospheric aerosol was studied by X-ray diffraction by sampling with a cascade impactor without filters. Quantitative phase analysis of natural phases present in the atmospheric coarse aerosol was performed using a modified version of the computer program MENGE, that uses the standardless X-ray method developed by Rius for the quantitative analysis of multiphase mixtures, adapted for PC running. Presence of quartz, calcite and gypsum was identified in the atmospheric aerosol and we have quantified their amounts using the standardless method.

  3. Cascade Hierarchy in SUSY SU(5) GUT

    CERN Document Server

    Kojima, Kentaro; Takahashi, Ryo

    2010-01-01

    We study cascade hierarchy in supersymmetric SU(5) grand unified theory. The neutrino Dirac mass matrix of the cascade form can lead to the tri-bimaximal generation mixing at the leading order in the seesaw mechanism while the down quark mass matrix of a hybrid cascade form naturally gives the CKM structure. We embed such experimentally favored mass textures into supersymmetric SU(5) GUT, which gives a relation between the down quark and charged lepton mass matrices. Related phenomenologies, such as lepton flavor violating processes and leptogenesis, are also investigated in addition to lepton mixing angles.

  4. Cascades on clique-based graphs

    Science.gov (United States)

    Hackett, Adam; Gleeson, James P.

    2013-06-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly clustered random graphs introduced by Gleeson [J. P. Gleeson, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.80.036107 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  5. Multi-elemental analysis of atmospheric pollutants and determination of particle size using the PIXE method, a cascade impactor and a filter unit constructed in Mexico; Analisis multielemental de contaminantes atmosfericos y determinacion de tamano de particula utilizando el metodo PIXE, un impactor de cascada y una unidad de filtro construidos en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Aldape U, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1989-01-15

    This work presents: 1) The methodology and the experimental conditions of the PIXE technique so that it is used as a better option inside the analytical methods in aerosols studies, 2) The development, tests and applications of a cascade impactor of the Batelle type built to determine particle size to use it jointly with the mentioned technique in the determination of the elements concentration according to its size.By this way is fulfilled with the first goal of this extensive project. (Author)

  6. Quantum Cascade Laser Frequency Combs

    CERN Document Server

    Faist, Jérôme; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the fir...

  7. SLAC T-510: Radio emission from particle cascades in the presence of a magnetic field

    Science.gov (United States)

    Mulrey, Katharine

    2017-03-01

    Cosmic ray induced particle cascades radiate in radio frequencies in the Earth's atmosphere. Geomagnetic and Askaryan emission provide an effective way to detect ultra-high energy cosmic rays. The SLAC T-510 experiment was the first to measure magnetically induced radiation from particle cascades in a controlled laboratory setting. An electron beam incident upon a dense dielectric target produced a particle cascade in the presence of a variable magnetic field. Antennas covering a band of 30-3000 MHz sampled RF emission in vertical and horizontal polarizations. Results from T-510 are compared to particle-level RF-emission simulations which are critical for reconstructing the energy and composition of detected ultra-high energy cosmic ray air showers. We discuss the experimental set up, the data processing, the systematic errors and the main results of the experiment, which we found in a good agreement with the simulations.

  8. Power scaling of high efficiency 1.5micron cascaded Raman fiber lasers

    CERN Document Server

    Supradeepa, V R

    2013-01-01

    High power fiber lasers operating at the 1.5micron wavelength region have attractive features like eye-safety and atmospheric transparency, and cascaded Raman fiber lasers offer a convenient method to obtain high power sources at these wavelengths. A limitation to power scaling however has been the lower conversion efficiency of these lasers. We recently introduced a high efficiency architecture for high power cascaded Raman fiber lasers applicable for 1.5micron fiber lasers. Here we demonstrate further power scaling using this new architecture. Using numerical simulations we identify the ideal operating conditions for the new architecture. We demonstrate a high efficiency 1480nm cascaded Raman fiber laser with an output power of 301 W, comparable to record power levels achieved with rare-earth doped fiber lasers in the 1.5 micron wavelength region.

  9. North Cascades Grizzly Bear Ecosystem Evaluation

    Data.gov (United States)

    Oak Ridge National Laboratory — We conducted a 6-year evaluation of the North Cascades Grizzly Bear Ecosystem (NCGBE) in north-central Washington to determine the suitability of the area to support...

  10. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim

    2002-01-01

    In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...... by a standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations...

  11. Cascade of period doublings of tori

    Science.gov (United States)

    Arneodo, A.; Coullet, P. H.; Spiegel, E. A.

    1983-02-01

    A three-dimensional map is proposed to model the effects of periodic forcing on a system displaying a transition to chaos through a cascade of period-doubling bifurcations. The study outlined here raises the problem of the existence and bifurcation of invariant tori. A principal feature of the simulations of both the differential equations and the discrete dynamical systems is that it is possible to disrupt period-doubling sequences (and inverse sequences as well) by periodic external forcing. Even though the way in which this abortion works is not understood, the mechanism is thought to be associated with the destruction of tori (Aronson et al., 1982) when the system is on the verge of bifurcation. The simulations therefore suggest that in moving farther along the cascade, the tori become more fragile. It is suspected that for arbitrarily weak driving, the cascade will eventually be disrupted after the cascade has proceeded through a sufficient number of steps.

  12. Bursting behaviours in cascaded stimulated Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov-Maxwell system.A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma.It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light,as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction.The bursting time in the reflectivity is found to be less than half the ion acoustic period.The ion temperature can affect the stimulated Brillouin scattering cascade,which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures.For stimulated Brillouin scattering saturation,higher-harmonic generation and wave-wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter.In addition,stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light.

  13. Picturing perturbative parton cascades in QCD matter

    Directory of Open Access Journals (Sweden)

    Aleksi Kurkela

    2015-01-01

    Full Text Available Based on parametric reasoning, we provide a simple dynamical picture of how a perturbative parton cascade, in interaction with a QCD medium, fills phase space as a function of time.

  14. MAP kinase cascades in Arabidopsis innate immunity

    DEFF Research Database (Denmark)

    Rasmussen, Magnus Wohlfahrt; Roux, Milena Edna; Petersen, Morten

    2012-01-01

    Plant mitogen-activated protein kinase (MAPK) cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs) by host transmembrane pattern recognition receptors which trigger MAPK-dependent innate ...

  15. Chemoenzymatic cascade processes for sustainable organic synthesis

    NARCIS (Netherlands)

    Simons, C.

    2007-01-01

    Chemical production processes often require wasteful and expensive isolation as well as purification of intermediates. Catalytic cascades offer a unique opportunity to eliminate these inefficient and polluting steps, in particular when carefully orchestrated, involving enzymes and chemocatalysts. Th

  16. Model for cascading failures in congested Internet

    Institute of Scientific and Technical Information of China (English)

    Jian WANG; Yan-heng LIU; Jian-qi ZHU; Yu JIAO

    2008-01-01

    Cascading failures often occur in congested networks such as the Internet. A cascading failure can be described as a three-phase process: generation, diffusion, and dissipation of the congestion. In this account, we present a function that represents the extent of congestion on a given node. This approach is different from existing functions based on betweenness centrality. By introducing the concept of 'delay time', we designate an intergradation between permanent removal and nouremoval. We also construct an evaluation function of network efficiency, based on congestion, which measures the damage caused by cascading failures. Finally, we investigate the effects of network structure and size, delay time, processing ability and packet generation speed on congestion propagation. Also, we uncover the relationship between the cascade dynamics and some properties of the network such as structure and size.

  17. Transport properties of cascading gauge theories

    CERN Document Server

    Buchel, A

    2005-01-01

    Cascading gauge theories of Klebanov et.al. provide a model within a framework of gauge theory/string theory duality for a four dimensional non-conformal gauge theory with a spontaneously generated mass scale. Using the dual supergravity description we study sound wave propagation in strongly coupled cascading gauge theory plasma. We analytically compute the speed of sound and the bulk viscosity of cascading gauge theory plasma at a temperature much larger than the strong coupling scale of the theory. The sound wave dispersion relation is obtained from the hydrodynamic pole in the stress-energy tensor two-point correlation function. The speed of sound extracted from the pole of the correlation function agrees with its value computed in [hep-th/0506002] using the equation of state. We find that the bulk viscosity of the hot cascading gauge theory plasma is non-zero at the leading order in the deviation from conformality.

  18. A quantum cascade phonon-polariton laser

    CERN Document Server

    Ohtani, Keita; Bosco, Lorenzo; Beck, Mattias; Faist, Jérôme

    2016-01-01

    We report a laser that coherently emits phonon-polaritons, quasi-particles arising from the coupling between photons and transverse optical phonons. The gain is provided by an intersubband transition in a quantum cascade structure. The polaritons at h$\

  19. Innovation cascades: artefacts, organization and attributions.

    Science.gov (United States)

    Lane, David A

    2016-03-19

    Innovation cascades inextricably link the introduction of new artefacts, transformations in social organization, and the emergence of new functionalities and new needs. This paper describes a positive feedback dynamic, exaptive bootstrapping, through which these cascades proceed, and the characteristics of the relationships in which the new attributions that drive this dynamic are generated. It concludes by arguing that the exaptive bootstrapping dynamic is the principal driver of our current Innovation Society.

  20. Cascade Textures and SUSY SO(10) GUT

    CERN Document Server

    Adulpravitchai, Adisorn; Takahashi, Ryo

    2010-01-01

    We give texture analyses of cascade hierarchical mass matrices in supersymmetric SO(10) grand unified theory. We embed cascade mass textures of the standard model fermion with right-handed neutrinos into the theory, which gives relations among the mass matrices of the fermions. The related phenomenologies, such as the lepton flavor violating processes and leptogenesis, are also investigated in addition to the PMNS mixing angles.

  1. Supersonic Chordwise Bending Flutter in Cascades

    Science.gov (United States)

    1975-05-31

    such a flutter boundary can be made by utilizing the trend lines predicted from a supersonic analysis based on supersonic cascade theory (Appendix I...bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD

  2. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  3. Emergence of event cascades in inhomogeneous networks

    Science.gov (United States)

    Onaga, Tomokatsu; Shinomoto, Shigeru

    2016-09-01

    There is a commonality among contagious diseases, tweets, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlling a system to tame or facilitate fluctuations in the event-occurrences. The critical interaction for the emergence of cascades depends greatly on the network structure in which individuals are connected. We demonstrate that we can predict whether cascades may emerge, given information about the interactions between individuals. Furthermore, we develop a method of reallocating connections among individuals so that event cascades may be either impeded or impelled in a network.

  4. Quantum Cascade Photonic Crystal lasers

    Science.gov (United States)

    Capasso, Federico

    2004-03-01

    QC lasers have emerged in recent years as the dominant laser technology for the mid-to far infrared spectrum in light of their room temperature operation, their tunability, ultrahigh speed operation and broad range of applications to chemical sensing, spectroscopy etc. (Ref. 1-3). After briefly reviewing the latter, I will describe a new class of mid-infrared QC lasers, Quantum Cascade Photonic Crystal Surface Emitting Lasers (QCPCSELS), that combine electronic and photonic band structure engineering to achieve vertical emission from the surface (Ref. 4). Devices operating on bandedge mode and on defect modes will be discussed. Exciting potential uses of these new devices exist in nonlinear optics, microfluidics as well as novel sensors. Finally a bird's eye view of other exciting areas of QC laser research will be given including broadband QCLs and new nonlinear optical sources based on multiwavelength QCLs. 1. F. Capasso, C. Gmachl, D. L. Sivco, and A. Y. Cho, Physics Today 55, 34 (May 2002) 2. F. Capasso, C. Gmachl, R. Paiella, A. Tredicucci, A. L. Hutchinson, D. L. Sivco, J. N. Baillargeon, A. Y. Cho and H. C. Liu, IEEE Journal of Selected Topics in Quantum Electronics, 6, 931 (2000). 3. F. Capasso, R. Paiella, R. Martini, R. Colombelli, C. Gmachl, T. L. Myers, M. S. Taubman, R. M. Williams, C. G. Bethea, K. Unterrainer, H. Y. Hwang, D. L. Sivco, A. Y. Cho, A. M. Sergent, H. C. Liu, E. A. Whittaker, IEEE J. Quantum Electron. 38, 511 (2002) 4. R. Colombelli, K. Srivasan, M. Troccoli, O. Painter, C. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho and F. Capasso, Science 302, 1374 (2003)

  5. On the importance of cascading moisture recycling in South America

    Directory of Open Access Journals (Sweden)

    D. C. Zemp

    2014-06-01

    Full Text Available Continental moisture recycling is a crucial process of the South American climate system. Evapotranspiration from the Amazon river basin contributes to precipitation regionally and in the La Plata river basin. Here we present an in-depth analysis of South American moisture recycling. We quantify the importance of "cascading moisture recycling", which describes the exchange of moisture between the vegetation and the atmosphere through precipitation and re-evaporation cycles on its way between two locations on the continent. We use the Water Accounting Model 2-layers (WAM-2layers forced by precipitation from TRMM and evapotranspiration from MODIS for the period 2001 until 2010 to construct moisture recycling networks. These networks describe the direction and amount of moisture transported from its source (evapotranspiration to its destination (precipitation in South America. Model-based calculations of continental and regional recycling ratios in the Amazon basin compare well with other existing studies using different datasets and methodologies. Our results show that cascading moisture recycling contributes about 10% to the total precipitation over South America and 17% over the La Plata basin. Considering cascading moisture recycling increases the total dependency of the La Plata basin on moisture from the Amazon basin by about 25% from 23 to 29% during the wet season. Using tools from complex network analysis, we reveal the importance of the south-western part of the Amazon basin as a key intermediary region for continental moisture transport in South America during the wet season. Our results suggest that land use change in this region might have a stronger impact on downwind rainfed agriculture and ecosystem stability than previously thought.

  6. Period-doubling cascades for large perturbations of Henon families

    OpenAIRE

    Sander, Evelyn; Yorke, James A.

    2009-01-01

    The Henon family has been shown to have period-doubling cascades. We show here that the same occurs for a much larger class: Large perturbations do not destroy cascades. Furthermore, we can classify the period of a cascade in terms of the set of orbits it contains, and count the number of cascades of each period. This class of families extends a general theory explaining why cascades occur.

  7. The Dutch N-cascade in the European perspective

    Institute of Scientific and Technical Information of China (English)

    Jan Willem Erisman; Nelleke Domburg; Wim de Vries; Hans Kros; Bronno de Haan; Kaj Sanders

    2005-01-01

    The Netherlands is "well known" for its nitrogen problems; it has one of the highest reactive nitrogen (Nr) emission densities in the world. It is a small country at the delta of several large European rivers. Ever since the industrial revolution, there has been a growing excess of nutrients and related emissions into the atmosphere (ammonia, nitrogen oxides and nitrous oxide)and into groundwater and surface water (nitrate), leading to a large range of cascading environmental impacts. Vehicular traffic, sewage and animal husbandry are the main sources of oxidized and reduced forms of Nr. This paper provides an overview of the origin and fate of nitrogen in the Netherlands, the various reported impacts of nitrogen, the Dutch and European policies to reduce nitrogen emissions and related impacts. In addition, ways are presented to go forward to potentially solve the problems in a European perspective. Solutions include the improvement of nitrogen efficiencies in different systems, technological options and education.

  8. Cascade reactions catalyzed by metal organic frameworks.

    Science.gov (United States)

    Dhakshinamoorthy, Amarajothi; Garcia, Hermenegildo

    2014-09-01

    Cascade or tandem reactions where two or more individual reactions are carried out in one pot constitute a clear example of process intensification, targeting the maximization of spatial and temporal productivity with mobilization of minimum resources. In the case of catalytic reactions, cascade processes require bi-/multifunctional catalysts that contain different classes of active sites. Herein, we show that the features and properties of metal-organic frameworks (MOFs) make these solids very appropriate materials for the development of catalysts for cascade reactions. Due to composition and structure, MOFs can incorporate different types of sites at the metal nodes, organic linkers, or at the empty internal pores, allowing the flexible design and synthesis of multifunctional catalysts. After some introductory sections on the relevance of cascade reactions from the point of view of competitiveness, sustainability, and environmental friendliness, the main part of the text provides a comprehensive review of the literature reporting the use of MOFs as heterogeneous catalysts for cascade reactions including those that combine in different ways acid/base, oxidation/reduction, and metal-organic centers. The final section summarizes the current state of the art, indicating that the development of a first commercial synthesis of a high-added-value fine chemical will be a crucial milestone in this area.

  9. Cascading climate effects and related ecological consequences during past centuries

    Directory of Open Access Journals (Sweden)

    B. Naef-Daenzer

    2012-10-01

    Full Text Available The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major population in Switzerland in relation to climate and habitat phenology. Using structural equation analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea – Caspian Pattern, NCP on habitat and breeding phenology, and further on fitness-relevant life history traits within great tit populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and productivity on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the structural equation model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, productivity and consequently, tit population fluctuations with minima during the "Maunder Minimum" (∼ 1650–1720 and the Little Ice Age Type Event I (1810–1850. The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, the impact of the NAO and NCP has contributed to an unprecedented increase of the population. A verification of the structural equation model against two independent data series (1970–2000 and 1750–1900 corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large-scale climate conditions substantially affect major life history parameters within a population, and thus

  10. Cascading climate effects and related ecological consequences during past centuries

    Directory of Open Access Journals (Sweden)

    B. Naef-Daenzer

    2012-06-01

    Full Text Available The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major population in Switzerland in relation to climate and habitat phenology. Using path analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea – Caspian Pattern, NCP on habitat and breeding phenology, and further on fitness-relevant life history traits within animal populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and population dynamics on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the path model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, and consequently, tit population minima during the "Maunder Minimum" (1650–1720 and the Little Ice Age Type Event I (1810–1850. The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, an unprecedented increase of the population. A verification of the structural equation model against two independent data series corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large scale climate conditions substantially affect major life-history parameters within a population, and thus influence key ecosystem parameters at the scale of centuries.

  11. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...... localities of tensions between matter and the immaterial, the practical and the ideal, and subject and object. In the colloquial language there can, moreover, often seem to be something authentic or genuine about atmosphere, juxtaposing it to staging, which is implied to be something simulated or artificial....... This introduction seeks to outline how a number of scholars have addressed the relationship between staged atmospheres and experience, and thus highlight both the philosophical, social and political aspects of atmospheres...

  12. Emergence of event cascades in inhomogeneous networks

    CERN Document Server

    Onaga, Tomokatsu

    2016-01-01

    There is a commonality among contagious diseases, tweets, urban crimes, nuclear reactions, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states for the case of the weaker interaction are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, frequent crimes, or large fluctuations in nuclear reactions, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlli...

  13. Epidemic and Cascading Survivability of Complex Networks

    CERN Document Server

    Manzano, Marc; Ripoll, Jordi; Fagertun, Anna Manolova; Torres-Padrosa, Victor; Pahwa, Sakshi; Scoglio, Caterina

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present \\emph{epidemic survivability} ($ES$), a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose \\emph{cascading survivability} ($CS$), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from $ES$ and $CS$ it is possible to describe the vulnerability of a given network. We consider a set of 17 different compl...

  14. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA.

  15. MAP Kinase Cascades in Plant Innate Immunity

    Directory of Open Access Journals (Sweden)

    Magnus Wohlfahrt Rasmussen

    2012-07-01

    Full Text Available Plant mitogen-activated protein kinase (MAPK cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs by host transmembrane pattern recognition receptors (PRRs which trigger MAPK-dependent innate immune responses. In the model Arabidopsis, molecular genetic evidence implicates a number of MAPK cascade components in PAMP signaling, and in responses to immunity-related phytohormones such as ethylene, jasmonate and salicylate. In a few cases, cascade components have been directly linked to the transcription of target genes or to the regulation of phytohormone synthesis. Thus MAPKs are obvious targets for bacterial effector proteins and are likely guardees of resistance (R proteins, which mediate defense signaling in response to the action of effectors, or effector-triggered immunity (ETI. This mini-review discusses recent progress in this field with a focus on the Arabidopsis MAPKs MPK3, 4, 6 and 11 in their apparent pathways.

  16. Bifurcations analysis of turbulent energy cascade

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2015-03-15

    This note studies the mechanism of turbulent energy cascade through an opportune bifurcations analysis of the Navier–Stokes equations, and furnishes explanations on the more significant characteristics of the turbulence. A statistical bifurcations property of the Navier–Stokes equations in fully developed turbulence is proposed, and a spatial representation of the bifurcations is presented, which is based on a proper definition of the fixed points of the velocity field. The analysis first shows that the local deformation can be much more rapid than the fluid state variables, then explains the mechanism of energy cascade through the aforementioned property of the bifurcations, and gives reasonable argumentation of the fact that the bifurcations cascade can be expressed in terms of length scales. Furthermore, the study analyzes the characteristic length scales at the transition through global properties of the bifurcations, and estimates the order of magnitude of the critical Taylor-scale Reynolds number and the number of bifurcations at the onset of turbulence.

  17. Piscivores, Trophic Cascades, and Lake Management

    Directory of Open Access Journals (Sweden)

    Ray W. Drenner

    2002-01-01

    Full Text Available The concept of cascading trophic interactions predicts that an increase in piscivore biomass in lakes will result in decreased planktivorous fish biomass, increased herbivorous zooplankton biomass, and decreased phytoplankton biomass. Though often accepted as a paradigm in the ecological literature and adopted by lake managers as a basis for lake management strategies, the trophic cascading interactions hypothesis has not received the unequivocal support (in the form of rigorous experimental testing that might be expected of a paradigm. Here we review field experiments and surveys, testing the hypothesis that effects of increasing piscivore biomass will cascade down through the food web yielding a decline in phytoplankton biomass. We found 39 studies in the scientific literature examining piscivore effects on phytoplankton biomass. Of the studies, 22 were confounded by supplemental manipulations (e.g., simultaneous reduction of nutrients or removal of planktivores and could not be used to assess piscivore effects. Of the 17 nonconfounded studies, most did not find piscivore effects on phytoplankton biomass and therefore did not support the trophic cascading interactions hypothesis. However, the trophic cascading interactions hypothesis also predicts that lake systems containing piscivores will have lower phytoplankton biomass for any given phosphorus concentration. Based on regression analyses of chlorophyll�total phosphorus relationships in the 17 nonconfounded piscivore studies, this aspect of the trophic cascading interactions hypothesis was supported. The slope of the chlorophyll vs. total phosphorus regression was lower in lakes with planktivores and piscivores compared with lakes containing only planktivores but no piscivores. We hypothesize that this slope can be used as an indicator of “functional piscivory” and that communities with extremes of functional piscivory (zero and very high represent classical 3- and 4-trophic level

  18. Cascaded logic gates in nanophotonic plasmon networks.

    Science.gov (United States)

    Wei, Hong; Wang, Zhuoxian; Tian, Xiaorui; Käll, Mikael; Xu, Hongxing

    2011-07-12

    Optical computing has been pursued for decades as a potential strategy for advancing beyond the fundamental performance limitations of semiconductor-based electronic devices, but feasible on-chip integrated logic units and cascade devices have not been reported. Here we demonstrate that a plasmonic binary NOR gate, a 'universal logic gate', can be realized through cascaded OR and NOT gates in four-terminal plasmonic nanowire networks. This finding provides a path for the development of novel nanophotonic on-chip processor architectures for future optical computing technologies.

  19. Cascade morphology transition in bcc metals.

    Science.gov (United States)

    Setyawan, Wahyu; Selby, Aaron P; Juslin, Niklas; Stoller, Roger E; Wirth, Brian D; Kurtz, Richard J

    2015-06-10

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N(F) ~ E(MD)(b)). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, μ, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of μ as a function of displacement threshold energy, E(d), is presented for bcc metals.

  20. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory. ©2010 IEEE....... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  1. Self-organized model of cascade spreading

    Science.gov (United States)

    Gualdi, S.; Medo, M.; Zhang, Y.-C.

    2011-01-01

    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a minimal self-organized model of cascade spreading based on a probabilistic response of the system elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation. For a wide range of parameters, the system is in a critical state and displays a power-law cascade-size distribution similar to the empirically observed one. We further generalize the model to reproduce volatility clustering and other observed properties of real stocks.

  2. Self-organized model of cascade spreading

    CERN Document Server

    Gualdi, Stanislao; Zhang, Yi-Cheng

    2010-01-01

    We study simultaneous price drops of real stocks and show that for high drop thresholds they follow a power-law distribution. To reproduce these collective downturns, we propose a self-organized model of cascade spreading based on a probabilistic response of the system's elements to stress conditions. This model is solvable using the theory of branching processes and the mean-field approximation and displays a power-law cascade-size distribution-similar to the empirically observed one-over a wide range of parameters.

  3. Dynamics of Soliton Cascades in Fiber Amplifiers

    CERN Document Server

    Arteaga-Sierra, F R; Agrawal, Govind P

    2016-01-01

    We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of input pulses.

  4. Energy cascade in internal wave attractors

    CERN Document Server

    Brouzet, Christophe; Joubaud, Sylvain; Sibgatullin, Ilias; Dauxois, Thierry

    2016-01-01

    One of the pivotal questions in the dynamics of the oceans is related to the cascade of mechanical energy in the abyss and its contribution to mixing. Here, we propose internal wave attractors in the large amplitude regime as a unique self-consistent experimental and numerical setup that models a cascade of triadic interactions transferring energy from large-scale monochro-matic input to multi-scale internal wave motion. We also provide signatures of a discrete wave turbulence framework for internal waves. Finally, we show how beyond this regime, we have a clear transition to a regime of small-scale high-vorticity events which induce mixing. Introduction.

  5. Exoplanet Atmospheres

    CERN Document Server

    Seager, S

    2010-01-01

    At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and u...

  6. Atmospheric Neutrinos

    OpenAIRE

    Takaaki Kajita

    1994-01-01

    Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses...

  7. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design...

  8. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  9. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  10. Quantum-engineered interband cascade photovoltaic devices

    Science.gov (United States)

    Yang, Rui Q.; Lotfi, Hossein; Li, Lu; Hinkey, Robert T.; Ye, Hao; Klem, John F.; Lei, L.; Mishima, T. D.; Keay, J. C.; Santos, M. B.; Johnson, M. B.

    2013-12-01

    Quantum-engineered multiple stage photovoltaic (PV) devices are explored based on InAs/GaSb/AlSb interband cascade (IC) structures. These ICPV devices employ multiple discrete absorbers that are connected in series by widebandgap unipolar barriers using type-II heterostructure interfaces for facilitating carrier transport between cascade stages similar to IC lasers. The discrete architecture is beneficial for improving the collection efficiency and for spectral splitting by utilizing absorbers with different bandgaps. As such, the photo-voltages from each individual cascade stage in an ICPV device add together, creating a high overall open-circuit voltage, similar to conventional multi-junction tandem solar cells. Furthermore, photo-generated carriers can be collected with nearly 100% efficiency in each stage. This is because the carriers travel over only a single cascade stage, designed to be shorter than a typical diffusion length. The approach is of significant importance for operation at high temperatures where the diffusion length is reduced. Here, we will present our recent progress in the study of ICPV devices, which includes the demonstration of ICPV devices at room temperature and above with narrow bandgaps (e.g. 0.23 eV) and high open-circuit voltages.

  11. Geothermal research, Oregon Cascades: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  12. Gene regulation by MAP kinase cascades

    DEFF Research Database (Denmark)

    Fiil, Berthe Katrine; Petersen, Klaus; Petersen, Morten

    2009-01-01

    Mitogen-activated protein kinase (MAPK) cascades are signaling modules that transduce extracellular stimuli to a range of cellular responses. Research in yeast and metazoans has shown that MAPK-mediated phosphorylation directly or indirectly regulates the activity of transcription factors. Plant ...

  13. Forecasting Social Unrest Using Activity Cascades.

    Science.gov (United States)

    Cadena, Jose; Korkmaz, Gizem; Kuhlman, Chris J; Marathe, Achla; Ramakrishnan, Naren; Vullikanti, Anil

    2015-01-01

    Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011) to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach.

  14. Modeling and simulation of cascading contingencies

    Science.gov (United States)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  15. Nested Canalyzing, Unate Cascade, and Polynomial Functions.

    Science.gov (United States)

    Jarrah, Abdul Salam; Raposa, Blessilda; Laubenbacher, Reinhard

    2007-09-15

    This paper focuses on the study of certain classes of Boolean functions that have appeared in several different contexts. Nested canalyzing functions have been studied recently in the context of Boolean network models of gene regulatory networks. In the same context, polynomial functions over finite fields have been used to develop network inference methods for gene regulatory networks. Finally, unate cascade functions have been studied in the design of logic circuits and binary decision diagrams. This paper shows that the class of nested canalyzing functions is equal to that of unate cascade functions. Furthermore, it provides a description of nested canalyzing functions as a certain type of Boolean polynomial function. Using the polynomial framework one can show that the class of nested canalyzing functions, or, equivalently, the class of unate cascade functions, forms an algebraic variety which makes their analysis amenable to the use of techniques from algebraic geometry and computational algebra. As a corollary of the functional equivalence derived here, a formula in the literature for the number of unate cascade functions provides such a formula for the number of nested canalyzing functions.

  16. Cascading effects of overfishing marine systems

    NARCIS (Netherlands)

    Scheffer, M.; Carpenter, S.; Young, de B.

    2005-01-01

    Profound indirect ecosystem effects of overfishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food

  17. Cascades with coupled map lattices in preferential attachment community networks

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zhao Xiao-Mei

    2008-01-01

    In this paper,cascading failure is studied by coupled map lattice (CML) methods in preferential attachment community networks.It is found that external perturbation R is increasing with modularity Q growing by simulation.In particular,the large modularity Q can hold off the cascading failure dynamic process in community networks.Furthermore,different attack strategies also greatly affect the cascading failure dynamic process. It is particularly significant to control cascading failure process in real community networks.

  18. Detailed comparison between parton cascade and hadronic cascade at SPS and RHIC

    CERN Document Server

    Nara, Y; Longacre, R S

    1999-01-01

    We study the importance of the partonic phase produced in relativistic heavy ion collision by comparing the parton cascade model and the hadronic cascade model. Hadron yield, baryon stopping and transverse momentum distribution are calculated with JAM and discussions are given comparing with VNI. Both of these models give good description of experimental data. We also discuss the strangeness production mechanism and the directed transverse flow. (21 refs).

  19. Possible explanation of the atmospheric kinetic and potential energy spectra.

    Science.gov (United States)

    Vallgren, Andreas; Deusebio, Enrico; Lindborg, Erik

    2011-12-23

    We hypothesize that the observed wave number spectra of kinetic and potential energy in the atmosphere can be explained by assuming that there are two related cascade processes emanating from the same large-scale energy source, a downscale cascade of potential enstrophy, giving rise to the k(-3) spectrum at synoptic scales and a downscale energy cascade giving rise to the k(-5/3) spectrum at mesoscales. The amount of energy which is going into the downscale energy cascade is determined by the rate of system rotation, with negligible energy going downscale in the limit of very fast rotation. We present a set of simulations of a system with strong rotation and stratification, supporting these hypotheses and showing good agreement with observations.

  20. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... characteristics of atmosphere as a spatial phenomenon, the aim of this text is to illustrate these associations and draw out design protocols, focusing on ways in which atmosphere can be conditioned architecturally. In other words, the objective is to trace the conceptual contours of ‘atmospheric materiality’....

  1. Higher-order Kerr effect and harmonic cascading in gases

    CERN Document Server

    Bache, Morten; Minardi, Stefano

    2012-01-01

    The higher-order Kerr effect (HOKE) has been recently advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity.

  2. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    , the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...... as a spatial phenomenon, exploring a multiplicity of conditions that constitute their resonant origins – i.e. the production sites from and within they have emerged. The intention is also to argue that despite the fact that atmosphere as an aesthetic category has crystallised over the last few decades...... contextualisation – provides a platform for revealing productive entanglements between heterogeneous elements, disciplines and processes. It also allows rendering atmosphere as a site of co-production open to contingencies and affective interplay on multiples levels: at the moment of its conceptualisation...

  3. Atmospheric composition

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

    The earth's atmosphere is made up of a number of gases in different relative amounts. Near sea level and up to about 90 km, the amount of these atmospheric gases in clean, relatively dry air is practically constant. Four of these gases, nitrogen, oxygen, argon, and carbon dioxide, make up 99.99 percent by volume of the atmosphere. Two gases, ozone and water vapor, change in relative amounts, but the total amount of these two is very small compared to the amount of the other gases. The atmospheric composition shown in a table can be considered valid up to 90 km geometric altitude. Above 90 km, mainly because of molecular dissociation and diffusive separation, the composition changes.

  4. Study of acoustic resonance of cascades

    Science.gov (United States)

    Honjo, M.; Tominaga, T.

    Discrete sounds and vibrations from guide vanes due to acoustic resonance in the vane flow path, are experimentally investigated. Other causes of pure sounds in stationary vanes are considered, such as direct radiation from wake shedding vortices, bubble vortices or leading edges, and radial or axial modes of air columns. Two-dimensional cascade tests are performed under various conditions, and the data are compared with theoretical results of flat plate cascades. Three-dimensional ducted guide vane model tests are carried out to apply prototype guide vanes, and to confirm the resonance of the two-dimensional tests. Results show that frequency is more sensitive to chord length than pitch length, and the ratio of the fluctuation frequency to fluid sound velocity/pitch length is independent of the scale. Bubble vortices on concave surfaces or leading edges are not exciting sources; and under the limit of solidity, no exciting energy can generate acoustic resonance in correspondence to the mode.

  5. Estimating Cascading Failure Risk with Random Chemistry

    CERN Document Server

    Rezaei, Pooya; Eppstein, Margaret J

    2014-01-01

    The potential for cascading failure in power systems adds substantially to overall reliability risk. Monte Carlo sampling can be used with a power system model to estimate this impact, but doing so is computationally expensive. This paper presents a new approach to estimating the risk of large cascading blackouts triggered by multiple contingencies. The method uses a search algorithm (Random Chemistry) to identify blackout-causing contingencies, and then combines the results with outage probabilities to estimate overall risk. Comparing this approach with Monte Carlo sampling for two test cases (the IEEE RTS-96 and a 2383 bus model of the Polish grid) suggests that the new approach is at least two orders of magnitude faster than Monte Carlo, without introducing measurable bias. Moreover, the approach enables one to compute the contribution of individual component-failure probabilities to overall blackout risk, allowing one to quickly identify low-cost strategies for reducing risk. By computing the sensitivity ...

  6. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [Washington State Univ. Energy Program, Olympia, WA (United States); Mattheis, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Kunkle, R. [Washington State Univ. Energy Program, Olympia, WA (United States); Howard, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Lubliner, M. [Washington State Univ. Energy Program, Olympia, WA (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions: 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  7. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A.; Mattheis, L.; Kunkle, R.; Howard, L.; Lubliner, M.

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  8. Cascaded trans-z-source inverters

    DEFF Research Database (Denmark)

    Li, Ding; Loh, Poh Chiang; Zhu, Miao;

    2011-01-01

    Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...... the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental...

  9. Regimes of turbulence without an energy cascade

    CERN Document Server

    Barenghi, C F; Baggaley, A W

    2016-01-01

    Experiments and numerical simulations of turbulent $^4$He and $^3$He-B have established that, at hydrodynamic length scales larger than the average distance between quantum vortices, the energy spectrum obeys the same 5/3 Kolmogorov law which is observed in the homogeneous isotropic turbulence of ordinary fluids. The importance of the 5/3 law is that it points to the existence of a Richardson energy cascade from large eddies to small eddies. However, there is also evidence of quantum turbulent regimes without Kolmogorov scaling. This raises the important questions of why, in such regimes, the Kolmogorov spectrum fails to form, what is the physical nature of turbulence without energy cascade, and whether hydrodynamical models can account for the unusual behaviour of turbulent superfluid helium. In this work we describe simple physical mechanisms which prevent the formation of Kolmogorov scaling in the thermal counterflow, and analyze the conditions necessary for emergence of quasiclassical regime in quantum tu...

  10. Short distance properties of cascading gauge theories

    CERN Document Server

    Aharony, O; Yarom, A; Aharony, Ofer; Buchel, Alex; Yarom, Amos

    2006-01-01

    We study the short distance (large momentum) properties of correlation functions of cascading gauge theories by performing a tree-level computation in their dual gravitational background. We prove that these theories are holographically renormalizable; the correlators have only analytic ultraviolet divergences, which may be removed by appropriate local counterterms. We find that n-point correlation functions of properly normalized operators have the expected scaling in the semi-classical gravity (large N) limit: they scale as N_{eff}^{2-n} with N_{eff} proportional to ln(k/Lambda) where k is a typical momentum. Our analysis thus confirms the interpretation of the cascading gauge theories as renormalizable four-dimensional quantum field theories with an effective number of degrees of freedom which logarithmically increases with the energy.

  11. A Sulfur Hexafluoride Sensor Using Quantum Cascade and CO2 Laser-Based Photoacoustic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Helion Vargas

    2010-10-01

    Full Text Available The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m2. This work compares two photoacoustic spectrometers, one coupled to a CO2 laser and another one coupled to a Quantum Cascade (QC laser, for the detection of SF6. The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO2 laser and 50 ppbv for quantum cascade laser were obtained.

  12. Transonic Cascade Measurements to Support Analytical Modeling

    Science.gov (United States)

    2007-11-02

    RECEIVED JUL 0 12005 FINAL REPORT FOR: AFOSR GRANT F49260-02-1-0284 TRANSONIC CASCADE MEASUREMENTS TO SUPPORT ANALYTICAL MODELING Paul A. Durbin ...PAD); 650-723-1971 (JKE) durbin @vk.stanford.edu; eaton@vk.stanford.edu submitted to: Attn: Dr. John Schmisseur Air Force Office of Scientific Research...both spline and control points for subsequent wall shape definitions. An algebraic grid generator was used to generate the grid for the blade-wall

  13. Toward Order-of-Magnitude Cascade Prediction

    OpenAIRE

    Guo, Ruocheng; Shaabani, Elham; Bhatnagar, Abhinav; Shakarian, Paulo

    2015-01-01

    When a piece of information (microblog, photograph, video, link, etc.) starts to spread in a social network, an important question arises: will it spread to "viral" proportions -- where "viral" is defined as an order-of-magnitude increase. However, several previous studies have established that cascade size and frequency are related through a power-law - which leads to a severe imbalance in this classification problem. In this paper, we devise a suite of measurements based on "structural dive...

  14. Adaptive stabilization for cascade nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    陈岚萍; 王洪元; 吴波

    2004-01-01

    An adaptive controller of full state feedback for certain cascade nonlinear systems achieving input-to-state stability with respect to unknown bounded disturbance is designed using backstepping and control Lyapunov function (CLF)techniques. We show that unknown bounded disturbance can be estimated by update laws, which requires less information on unknown disturbance, as a part of stabilizing control. The design method achieves the desired property: global robust stability. Our contribution is illustrated with the example of a disturbed pendulum.

  15. Optical encryption with cascaded fractional wavelet transforms

    Institute of Scientific and Technical Information of China (English)

    BAO Liang-hua; CHEN Lin-fei; ZHAO Dao-mu

    2006-01-01

    On the basis of fractional wavelet transform, we propose a new method called cascaded fractional wavelet transform to encrypt images. It has the virtues of fractional Fourier transform and wavelet transform. Fractional orders, standard focal lengths and scaling factors are its keys. Multistage fractional Fourier transforms can add the keys easily and strengthen information security. This method can also realize partial encryption just as wavelet transform and fractional wavelet transform. Optical realization of encryption and decryption is proposed. Computer simulations confirmed its possibility.

  16. Controllability of nonlinear degenerate parabolic cascade systems

    Directory of Open Access Journals (Sweden)

    Mamadou Birba

    2016-08-01

    Full Text Available This article studies of null controllability property of nonlinear coupled one dimensional degenerate parabolic equations. These equations form a cascade system, that is, the solution of the first equation acts as a control in the second equation and the control function acts only directly on the first equation. We prove positive null controllability results when the control and a coupling set have nonempty intersection.

  17. Tip Clearance Flows in Turbine Cascades

    Institute of Scientific and Technical Information of China (English)

    Li Wei; Qiao Weiyang; Sun Dawei

    2008-01-01

    This article describes the effects of some factors on the tip clearance flow in axial linear turbine cascades.The measurements of the total pressure loss coefficient are made at the cascade outlets by using a five-hole probe at exit Mach numbers of 0.10,0.14 and 0.19.At each exit Mach number,experiments axe performed at the tip clearance heights of 1.0%,1.5%,2.0%,2.5% and 3.0% of the blade height.The effects of the non-uniform tip clearance height of each blade in the pitchwise direction are also studied.The results show that at a given tip clearance height,generally,total pressure loss rises with exit Mach numbers proportionally.At a fixed exit Mach number,the total pressure loss augments nearly proportionally as the tip clearance height increases.The increased tip clearance heights in the tip regions of two adjacent blades are to be blame for the larger clearance loss of the center blade.Compared to the effects of the tip clearance height,the effects of the exit Mach number and the pitchwise variation of the tip clearance height on the cascade total pressure loss are so less significant to be omitted.

  18. Cascade laser applications: trends and challenges

    Science.gov (United States)

    d'Humières, B.; Margoto, Éric; Fazilleau, Yves

    2016-03-01

    When analyses need rapid measurements, cost effective monitoring and miniaturization, tunable semiconductor lasers can be very good sources. Indeed, applications like on-field environmental gas analysis or in-line industrial process control are becoming available thanks to the advantage of tunable semiconductor lasers. Advances in cascade lasers (CL) are revolutionizing Mid-IR spectroscopy with two alternatives: interband cascade lasers (ICL) in the 3-6μm spectrum and quantum cascade lasers (QCL), with more power from 3 to 300μm. The market is getting mature with strong players for driving applications like industry, environment, life science or transports. CL are not the only Mid-IR laser source. In fact, a strong competition is now taking place with other technologies like: OPO, VCSEL, Solid State lasers, Gas, SC Infrared or fiber lasers. In other words, CL have to conquer a share of the Mid-IR application market. Our study is a market analysis of CL technologies and their applications. It shows that improvements of components performance, along with the progress of infrared laser spectroscopy will drive the CL market growth. We compare CL technologies with other Mid-IR sources and estimate their share in each application market.

  19. Cascading failures in ac electricity grids

    Science.gov (United States)

    Rohden, Martin; Jung, Daniel; Tamrakar, Samyak; Kettemann, Stefan

    2016-09-01

    Sudden failure of a single transmission element in a power grid can induce a domino effect of cascading failures, which can lead to the isolation of a large number of consumers or even to the failure of the entire grid. Here we present results of the simulation of cascading failures in power grids, using an alternating current (AC) model. We first apply this model to a regular square grid topology. For a random placement of consumers and generators on the grid, the probability to find more than a certain number of unsupplied consumers decays as a power law and obeys a scaling law with respect to system size. Varying the transmitted power threshold above which a transmission line fails does not seem to change the power-law exponent q ≈1.6 . Furthermore, we study the influence of the placement of generators and consumers on the number of affected consumers and demonstrate that large clusters of generators and consumers are especially vulnerable to cascading failures. As a real-world topology, we consider the German high-voltage transmission grid. Applying the dynamic AC model and considering a random placement of consumers, we find that the probability to disconnect more than a certain number of consumers depends strongly on the threshold. For large thresholds the decay is clearly exponential, while for small ones the decay is slow, indicating a power-law decay.

  20. HIV treatment cascade in tuberculosis patients

    Science.gov (United States)

    Lessells, Richard J.; Swaminathan, Soumya; Godfrey-Faussett, Peter

    2015-01-01

    Purpose of review Globally, the number of deaths associated with tuberculosis (TB) and HIV coinfection remains unacceptably high. We review the evidence around the impact of strengthening the HIV treatment cascade in TB patients and explore recent findings about how best to deliver integrated TB/HIV services. Recent findings There is clear evidence that the timely provision of antiretroviral therapy (ART) reduces mortality in TB/HIV coinfected adults. Despite this, globally in 2013, only around a third of known HIV-positive TB cases were treated with ART. Although there is some recent evidence exploring the barriers to achieve high coverage of HIV testing and ART initiation in TB patients, our understanding of which factors are most important and how best to address these within different health systems remains incomplete. There are some examples of good practice in the delivery of integrated TB/HIV services to improve the HIV treatment cascade. However, evidence of the impact of such strategies is of relatively low quality for informing integrated TB/HIV programming more broadly. In most settings, there remain barriers to higher-level organizational and functional integration. Summary There remains a need for commitment to patient-centred integrated TB/HIV care in countries affected by the dual epidemic. There is a need for better quality evidence around how best to deliver integrated services to strengthen the HIV treatment cascade in TB patients, both at primary healthcare level and within community settings. PMID:26352390

  1. Prediction of Cascading Failures in Spatial Networks.

    Science.gov (United States)

    Shunkun, Yang; Jiaquan, Zhang; Dan, Lu

    2016-01-01

    Cascading overload failures are widely found in large-scale parallel systems and remain a major threat to system reliability; therefore, they are of great concern to maintainers and managers of different systems. Accurate cascading failure prediction can provide useful information to help control networks. However, for a large, gradually growing network with increasing complexity, it is often impractical to explore the behavior of a single node from the perspective of failure propagation. Fortunately, overload failures that propagate through a network exhibit certain spatial-temporal correlations, which allows the study of a group of nodes that share common spatial and temporal characteristics. Therefore, in this study, we seek to predict the failure rates of nodes in a given group using machine-learning methods. We simulated overload failure propagations in a weighted lattice network that start with a center attack and predicted the failure percentages of different groups of nodes that are separated by a given distance. The experimental results of a feedforward neural network (FNN), a recurrent neural network (RNN) and support vector regression (SVR) all show that these different models can accurately predict the similar behavior of nodes in a given group during cascading overload propagation.

  2. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  3. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  4. Atmospheric Refraction

    CERN Document Server

    Nauenberg, Michael

    2016-01-01

    Calculations of atmospheric refraction are generally based on a simplified model of atmospheric density in the troposphere which assumes that the temperature decreases at a constant lapse rate from sea level up to a height equal to eleven km, and that afterwards it remains constant. In this model, the temperature divided by the lapse rate determines the length scale in the calculations for altitudes less than this height. But daily balloon measurements across the U.S.A. reveal that in some cases the air temperature actually increases from sea level up to a height of about one km, and only after reaching a plateau, it decreases at an approximately constant lapse rate. Moreover, in three examples considered here, the temperature does not remain constant at eleven km , but continues to decreases to a minimum at about sixteen kilometers , and then increases at higher altitudes at a lower rate. Calculations of atmospheric refraction based on this atmospheric data is compared with the results of simplified models.

  5. Dynamics of quantum cascade lasers: numerics

    Science.gov (United States)

    Van der Sande, Guy; Verschaffelt, Guy

    2016-04-01

    Since the original demonstration of terahertz quantum-cascade lasers (QCLs), the performance of these devices has shown rapid improvement. QCLs can now deliver milliwatts or more of continuous-wave radiation throughout the terahertz frequency range (300 GHz to 10 THz). Therefore, QCLs have become widely used in various applications such as spectroscopy, metrology or free-space telecommunications. For many of these applications there is a need for compact tuneable quantum cascade lasers. Nowadays most tuneable QCLs are based on a bulky external cavity configuration. We explore the possibility of tuning the operating wavelength through a fully integrated on-chip wavelength selective feedback applied to a dual wavelength QCL. Our numerical and analytical analyses are based on rate equation models describing the dynamics of QCLs extended to include delayed filtered optical feedback. We demonstrate the possibility to tune the operating wavelength by altering the absorption and/or amplification of the signal in the delayed feedback path. The tuning range of a laser is limited by the spectral width of its gain. For inter-band semiconductor lasers this spectral width is typically several tens of nm. Hence, the laser cavity supports the existence of multiple modes and on chip wavelength selective feedback has been demonstrated to be a promising tuning mechanism. We have selected a specific QCL gain structure with four energy levels and with two lasing transitions in the same cascade. In this scheme, the two lasing modes use a common upper level. Hence, the two modes compete in part for the same carriers to account for their optical gain. We have added delayed wavelength specific filtered optical feedback to the rate equation model describing these transitions. We have calculated the steady states and their stability in the absence of delay for the feedback field and studied numerically the case with non-zero delay. We have proven that wavelength tuning of a dual wavelength

  6. Heat cascading regenerative sorption heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1995-01-01

    A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

  7. Mixtures of multiplicative cascade models in geochemistry

    Directory of Open Access Journals (Sweden)

    F. P. Agterberg

    2007-05-01

    Full Text Available Multifractal modeling of geochemical map data can help to explain the nature of frequency distributions of element concentration values for small rock samples and their spatial covariance structure. Useful frequency distribution models are the lognormal and Pareto distributions which plot as straight lines on logarithmic probability and log-log paper, respectively. The model of de Wijs is a simple multiplicative cascade resulting in discrete logbinomial distribution that closely approximates the lognormal. In this model, smaller blocks resulting from dividing larger blocks into parts have concentration values with constant ratios that are scale-independent. The approach can be modified by adopting random variables for these ratios. Other modifications include a single cascade model with ratio parameters that depend on magnitude of concentration value. The Turcotte model, which is another variant of the model of de Wijs, results in a Pareto distribution. Often a single straight line on logarithmic probability or log-log paper does not provide a good fit to observed data and two or more distributions should be fitted. For example, geochemical background and anomalies (extremely high values have separate frequency distributions for concentration values and for local singularity coefficients. Mixtures of distributions can be simulated by adding the results of separate cascade models. Regardless of properties of background, an unbiased estimate can be obtained of the parameter of the Pareto distribution characterizing anomalies in the upper tail of the element concentration frequency distribution or lower tail of the local singularity distribution. Computer simulation experiments and practical examples are used to illustrate the approach.

  8. A stochastic model of cascades in 2D turbulence

    CERN Document Server

    Ditlevsen, Peter D

    2012-01-01

    The dual cascade of energy and enstrophy in 2D turbulence cannot easily be understood in terms of an analog to the Richardson-Kolmogorov scenario describing the energy cascade in 3D turbulence. The coherent up- and downscale fluxes points to non-locality of interactions in spectral space, and thus the specific spatial structure of the flow could be important. Shell models, which lack spacial structure and have only local interactions in spectral space, indeed fail in reproducing the correct scaling for the inverse cascade of energy. In order to exclude the possibility that non-locality of interactions in spectral space is crucial for the dual cascade, we introduce a stochastic spectral model of the cascades which is local in spectral space and which shows the correct scaling for both the direct enstrophy - and the inverse energy cascade.

  9. Fast automotive diesel exhaust measurement using quantum cascade lasers

    Science.gov (United States)

    Herbst, J.; Brunner, R.; Lambrecht, A.

    2013-12-01

    Step by step, US and European legislations enforce the further reduction of atmospheric pollution caused by automotive exhaust emissions. This is pushing automotive development worldwide. Fuel efficient diesel engines with SCRtechnology can impede NO2-emission by reduction with NH3 down to the ppm range. To meet the very low emission limits of the Euro6 resp. US NLEV (National Low Emission Vehicle) regulations, automotive manufacturers have to optimize continuously all phases of engine operation and corresponding catalytic converters. Especially nonstationary operation holds a high potential for optimizing gasoline consumption and further reducing of pollutant emissions. Test equipment has to cope with demanding sensitivity and speed requirements. In the past Fraunhofer IPM has developed a fast emission analyzer called DEGAS (Dynamic Exhaust Gas Analyzer System), based on cryogenically cooled lead salt lasers. These systems have been used at Volkswagen AG`s test benches for a decade. Recently, IPM has developed DEGAS-Next which is based on cw quantum cascade lasers and thermoelectrically cooled detectors. The system is capable to measure three gas components (i.e. NO, NO2, NH3) in two channels with a time resolution of 20 ms and 1 ppm detection limits. We shall present test data and a comparison with fast FTIR measurements.

  10. OBSERVING CASCADES OF SOLAR BULLETS AT HIGH RESOLUTION. II

    Energy Technology Data Exchange (ETDEWEB)

    Scullion, E.; Engvold, O.; Lin, Y.; Voort, L. Rouppe van der, E-mail: scullie@tcd.ie [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)

    2015-12-01

    High resolution observations from the Swedish 1-m Solar Telescope revealed bright, discrete, blob-like structures (which we refer to as solar bullets) in the Hα 656.28 nm line core that appear to propagate laterally across the solar atmosphere as clusters in active regions (ARs). These small-scale structures appear to be field aligned and many bullets become triggered simultaneously and traverse collectively as a cluster. Here, we conduct a follow-up study on these rapidly evolving structures with coincident observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly. With the co-aligned data sets, we reveal (a) an evolving multithermal structure in the bullet cluster ranging from chromospheric to at least transition region temperatures, (b) evidence for cascade-like behavior and corresponding bidirectional motions in bullets within the cluster, which indicate that there is a common source of the initial instability leading to bullet formation, and (c) a direct relationship between co-incident bullet velocities observed in Hα and He ii 30.4 nm and an inverse relationship with respect to bullet intensity in these channels. We find evidence supporting that bullets are typically composed of a cooler, higher density core detectable in Hα with a less dense, hotter, and fainter co-moving outer sheath. Bullets unequivocally demonstrate the finely structured nature of the AR corona. We have no clear evidence for bullets being associated with locally heated (or cooled), fast flowing plasma. Fast MHD pulses (such as solitons) could best describe the dynamic properties of bullets whereas the presence of a multithermal structure is new.

  11. Photonic crystal slab quantum cascade detector

    Energy Technology Data Exchange (ETDEWEB)

    Reininger, Peter, E-mail: peter.reininger@tuwien.ac.at; Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, Vienna 1040 (Austria)

    2013-12-09

    In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.

  12. Cascaded uncoupled dual-ring modulator

    CERN Document Server

    Gu, Tingyi; Wong, Chee Wei; Dong, Po

    2014-01-01

    We demonstrate that by coherent driving two uncoupled rings in same direction, the effective photon circulating time in the dual ring modulator is reduced, with increased modulation quality. The inter-ring detuning dependent photon dynamics, Q-factor, extinction ratio and optical modulation amplitude of two cascaded silicon ring resonators are studied and compared with that of a single ring modulator. Experimentally measured eye diagrams, together with coupled mode theory simulations, demonstrate the enhancement of dual ring configuration at 20 Gbps with a Q ~ 20,000.

  13. Tracking Control for Switched Cascade Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Dong

    2015-01-01

    Full Text Available The issue of H∞ output tracking for switched cascade nonlinear systems is discussed in this paper, where not all the linear parts of subsystems are stabilizable. The conditions of the solvability for the issue are given by virtue of the structural characteristics of the systems and the average dwell time method, in which the total activation time for stabilizable subsystems is longer than that for the unstabilizable subsystems. At last, a simulation example is used to demonstrate the validity and advantages of the proposed approach.

  14. The identification of a cascade hypernucleus

    CERN Document Server

    Mondal, A S; Husain, A; Kasim, M M

    1979-01-01

    In a systematic search for rare hypernuclear species in nuclear emulsion exposed to 3.0 GeV/c K/sup -/-mesons at the CERN PS, an event with three connecting stars has been observed. The two secondary stars are most probably due to the decay of a cascade hypernucleus according to the following channel: /sub Xi //sup -13/-C to /sub Lambda //sup 8 /Be+/sub Lambda //sup 5/He+Q. The binding energy of the Xi - hypernucleus is B/sub Xi /-(/sub Xi //sup 13/-C)=(18.1+or-3.2) MeV. (11 refs).

  15. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie

    2015-08-27

    © 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

  16. Direct and inverse cascades in the geodynamo

    CERN Document Server

    Reshetnyak, M

    2010-01-01

    The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We consider the model which enables us reproduce the typical features of small-scale geostrophic flows in physical and wave spaces. We present estimates of kinetic and magnetic energy fluxes as a function of the wave number. The joint existence of forward and inverse cascades are demonstrated. We also consider the mechanism of magnetic field saturation at the end of the kinematic dynamo regime.

  17. Beam combining of quantum cascade laser arrays.

    Science.gov (United States)

    Lee, Benjamin G; Kansky, Jan; Goyal, Anish K; Pflügl, Christian; Diehl, Laurent; Belkin, Mikhail A; Sanchez, Antonio; Capasso, Federico A

    2009-08-31

    Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.

  18. Multiplier phenomenology in random multiplicative cascade processes

    CERN Document Server

    Jouault, B; Greiner, M; Jouault, Bruno; Lipa, Peter; Greiner, Martin

    1999-01-01

    We demonstrate that the correlations observed in conditioned multiplier distributions of the energy dissipation in fully developed turbulence can be understood as an unavoidable artefact of the observation procedure. Taking the latter into account, all reported properties of both unconditioned and conditioned multiplier distributions can be reproduced by cascade models with uncorrelated random weights if their bivariate splitting function is non-energy conserving. For the alpha-model we show that the simulated multiplier distributions converge to a limiting form, which is very close to the experimentally observed one. If random translations of the observation window are accounted for, also the subtle effects found in conditioned multiplier distributions are precisely reproduced.

  19. Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking

    CERN Document Server

    Griffin, Tom; Horava, Petr; Yan, Ziqi

    2015-01-01

    Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion $\\omega\\sim k^n$ ($n=2,3,\\ldots$), whose naturalness is protected by polynomial shift symmetries. Here we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of $n$ changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.

  20. Long-Haul TCP vs. Cascaded TCP

    OpenAIRE

    Feng, Wu-chun

    2006-01-01

    In this work, we investigate the bandwidth and transfer time of long-haul TCP versus cascaded TCP [5]. First, we discuss the models for TCP throughput. For TCP flows in support of bulk data transfer (i.e., long-lived TCP flows), the TCP throughput models have been derived [2, 3]. These models rely on the congestion-avoidance algorithm of TCP. Though these models cannot be applied with short-lived TCP connections, our interest relative to logistical networking is in longer-li...

  1. Direct and inverse cascades in the geodynamo

    Directory of Open Access Journals (Sweden)

    M. Reshetnyak

    2008-11-01

    Full Text Available The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We investigate numerically a model based on the geodynamo equations in simplified geometry, which enables us to reproduce the main features of small-scale geostrophic flows in physical and wave vector spaces. We find fluxes of kinetic and magnetic energy as a function of the wave number and demonstrate the co-existence of forward and inverse cascades. We also explain the mechanism of magnetic field saturation at the end of the kinematic dynamo regime.

  2. Evaluating logic functionality of cascaded fracturable LUTs

    Institute of Scientific and Technical Information of China (English)

    GUO Zhenhong; LIN Yu; LI Tianyi; JIA Rui; GAO Tongqiang; YANG Haigang

    2016-01-01

    Look Up Tables(LUTs) are the key components of Field-Programmable Gate Arrays(FPGAs). Many LUT architectures have been studied; nevertheless, it is difficult to quantificationally evaluate an LUT based architecture. Traditionally, dedicated efforts on specific modifications to the technology mapping tools are required for LUT architecture evaluation. A more feasible evaluation method for logic functionality is strongly required for the design of LUT architecture. In this paper, a mathematical method for logic functionality calculation is proposed and conventional and fracturable LUT architectures are analyzed. Furthermore, a cascaded fracturable LUT architecture is presented, which achieves twice logic functionality compared with the conventional LUTs and fracturable LUTs.

  3. Application of Stereoscopic and Tomographic PIV in a Transonic Cascade

    OpenAIRE

    Klinner, Joachim; Willert, Christian

    2014-01-01

    The contribution demonstrates the applicability of volumetric PIV in a highly loaded compressor cascade at Ma_1 = 0.60. Under these operation conditions the secondary flow structures in the cascade are dominated by a passage vortex located at the base of the blade and near the suction side. The application of volume resolving thick-sheet PIV (or tomo-PIV) near the trailing edge of the cascades blades is intended to demonstrate the techniques potential of instantaneously resolving secondary fl...

  4. Stopping pions in high-energy nuclear cascades.

    Science.gov (United States)

    Jones, W. V.; Johnson, D. P.; Thompson, J. A.

    1973-01-01

    Results of Monte Carlo calculations for the number and energy spectra of charged pions from nuclear-electromagnetic cascades developing in rock are presented for primary hadron energies ranging from 3 to 3000 GeV. These spectra are given as functions of the longitudinal depth in the absorber and the lateral distance from the cascade axis. The number of charged pions which stop in the absorber increases with the primary energy of the hadron initiating the cascade.

  5. Damped trophic cascades driven by fishing in model marine ecosystems

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Pedersen, Martin

    2010-01-01

    that fishing does not change the overall slope of the size spectrum, but depletes the largest individuals and induces trophic cascades. A trophic cascade can propagate both up and down in trophic levels driven by a combination of changes in predation mortality and food limitation. The cascade is damped...... cascade triggered by the removal of top predators. Here we use a novel size- and trait-based model to explore how marine ecosystems might react to perturbations from different types of fishing pressure. The model explicitly resolves the whole life history of fish, from larvae to adults. The results show...

  6. Large-scale separation and hysteresis in cascades

    Science.gov (United States)

    Rothmayer, A. P.; Smith, F. T.

    1985-01-01

    An approach using a two-dimensional thin aerofoil, allied with the theory of viscous bluff-body separation, is used to study the initial cross-over from massive separation to an attached flow in a single-row unstaggered cascade. Analytic solutions are developed for the limit of small cascade-spacing. From the analytic solutions several interesting features of the cascade are examined, including multiple-solution branches and multiple regions of hysteresis. In addition, numerical results are presented for several selected aerofoils. Some of the aerofoils are found to contain markedly enlarged regions of hysteresis for certain critical cascade spacings.

  7. The role of AVDR in linear cascade testing

    Institute of Scientific and Technical Information of China (English)

    Bo Song; Wing F.Ng

    2007-01-01

    Linear cascade testing plays an important role in the research and development of turbomachinery and is widelv used over the world.The ideal cascade model of a turbomachinery blade row is two-dimensional.In actual linear cascade tesring,the flow through the test section converges due to the development of the boundary layer and secondary flow along the sidewall surfaces of the test section.Axial velocity density ratio(AVDR)is adopted to account for the deviation of the tested cascade flow from the ideal 2D model.Among numerous published cascade works,the influence of AVDR on cascade performance is seen to be complicated with many affecting factors,such as those related to cascade/blade geometry and flow conditions.Also,controlling AVDR is limited by the facility capability.Furthermore'real blade-to-blade flow in turborrlachines is usually associated with AVDR greater than unity due to limited span of blades between the hub and shroud such that cascade testing without reducing AVDR could be favored sometimes.All these facets add complexity and diversification to the matter.The current paper reviews previous studies and results on AVDR.ConsoIidated understanding on the role of AVDR and recommendations on how to deal with it in linear cascade testing are provided.

  8. Noise propagation in two-step series MAPK cascade.

    Directory of Open Access Journals (Sweden)

    Venkata Dhananjaneyulu

    Full Text Available Series MAPK enzymatic cascades, ubiquitously found in signaling networks, act as signal amplifiers and play a key role in processing information during signal transduction in cells. In activated cascades, cell-to-cell variability or noise is bound to occur and thereby strongly affects the cellular response. Commonly used linearization method (LM applied to Langevin type stochastic model of the MAPK cascade fails to accurately predict intrinsic noise propagation in the cascade. We prove this by using extensive stochastic simulations for various ranges of biochemical parameters. This failure is due to the fact that the LM ignores the nonlinear effects on the noise. However, LM provides a good estimate of the extrinsic noise propagation. We show that the correct estimate of intrinsic noise propagation in signaling networks that contain at least one enzymatic step can be obtained only through stochastic simulations. Noise propagation in the cascade depends on the underlying biochemical parameters which are often unavailable. Based on a combination of global sensitivity analysis (GSA and stochastic simulations, we developed a systematic methodology to characterize noise propagation in the cascade. GSA predicts that noise propagation in MAPK cascade is sensitive to the total number of upstream enzyme molecules and the total number of molecules of the two substrates involved in the cascade. We argue that the general systematic approach proposed and demonstrated on MAPK cascade must accompany noise propagation studies in biological networks.

  9. Nonlinear modeling of thermoacoustically driven energy cascade

    Science.gov (United States)

    Gupta, Prateek; Scalo, Carlo; Lodato, Guido

    2016-11-01

    We present an investigation of nonlinear energy cascade in thermoacoustically driven high-amplitude oscillations, from the initial weakly nonlinear regime to the shock wave dominated limit cycle. We develop a first principle based quasi-1D model for nonlinear wave propagation in a canonical minimal unit thermoacoustic device inspired by the experimental setup of Biwa et al.. Retaining up to quadratic nonlinear terms in the governing equations, we develop model equations for nonlinear wave propagation in the proximity of differentially heated no-slip boundaries. Furthermore, we discard the effects of acoustic streaming in the present study and focus on nonlinear energy cascade due to high amplitude wave propagation. Our model correctly predicts the observed exponential growth of the thermoacoustically amplified second harmonic, as well as the energy transfer rate to higher harmonics causing wave steepening. Moreover, we note that nonlinear coupling of local pressure with heat transfer reduces thermoacoustic amplification gradually thus causing the system to reach limit cycle exhibiting shock waves. Throughout, we verify the results from the quasi-1D model with fully compressible Navier-Stokes simulations.

  10. High efficiency quantum cascade laser frequency comb

    Science.gov (United States)

    Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

    2017-01-01

    An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm−1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy. PMID:28262834

  11. Quantitative analysis of cascade impactor samples - revisited

    Science.gov (United States)

    Orlić , I.; Chiam, S. Y.; Sanchez, J. L.; Tang, S. M.

    1999-04-01

    Concentrations of aerosols collected in Singapore during the three months long haze period that affected the whole South-East Asian region in 1997 are reported. Aerosol samples were continuously collected by using a fine aerosol sampler (PM2.5) and occasionally with a single orifice cascade impactor (CI) sampler. Our results show that in the fine fraction (<2.5 μm) the concentrations of two well-known biomass burning products, i.e. K and S were generally increased by a factor 2-3 compared to the non-hazy periods. However, a discrepancy was noticed, at least for elements with lower atomic number (Ti and below) between the results obtained by the fine aerosol sampler and the cascade impactor. Careful analysis by means of Nuclear Microscopy, in particular by the Scanning Transmission Ion Microscopy (STIM) technique, revealed that thicknesses of the lower CI stages exceeded thick target limits for 2 MeV protons. Detailed depth profiles of all CI stages were therefore measured using the STIM technique and concentrations corrected for absorption and proton energy loss. After correcting results for the actual sample thickness, concentrations of all major elements (S, Cl, K, Ca) agreed much better with the PM2.5 results. The importance of implementing thick target corrections in analysis of CI samples, especially those collected in the urban environments, is emphasized. Broad beam PIXE analysis approach is certainly not adequate in these cases.

  12. Frequency division using a micromechanical resonance cascade

    Energy Technology Data Exchange (ETDEWEB)

    Qalandar, K. R., E-mail: kamala@engineering.ucsb.edu; Gibson, B.; Sharma, M.; Ma, A.; Turner, K. L. [Department of Mechanical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106 (United States); Strachan, B. S. [Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan 48823 (United States); Department of Electrical Engineering, Michigan State University, East Lansing, Michigan 48823 (United States); Shaw, S. W. [Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan 48823 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48823 (United States)

    2014-12-15

    A coupled micromechanical resonator array demonstrates a mechanical realization of multi-stage frequency division. The mechanical structure consists of a set of N sequentially perpendicular microbeams that are connected by relatively weak elastic elements such that the system vibration modes are localized to individual microbeams and have natural frequencies with ratios close to 1:2:⋯:2{sup N}. Conservative (passive) nonlinear inter-modal coupling provides the required energy transfer between modes and is achieved by finite deformation kinematics. When the highest frequency beam is excited, this arrangement promotes a cascade of subharmonic resonances that achieve frequency division of 2{sup j} at microbeam j for j = 1, …, N. Results are shown for a capacitively driven three-stage divider in which an input signal of 824 kHz is passively divided through three modal stages, producing signals at 412 kHz, 206 kHz, and 103 kHz. The system modes are characterized and used to delineate the range of AC input voltages and frequencies over which the cascade occurs. This narrow band frequency divider has simple design rules that are scalable to higher frequencies and can be extended to a larger number of modal stages.

  13. High efficiency quantum cascade laser frequency comb

    Science.gov (United States)

    Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

    2017-03-01

    An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm‑1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy.

  14. Cascades and perturbed Morse-Bott functions

    CERN Document Server

    Banyaga, Augustin

    2011-01-01

    Let $f:M \\rightarrow \\mathbb{R}$ be a Morse-Bott function on a finite dimensional closed smooth manifold $M$. Choosing an appropriate Riemannian metric on $M$ and Morse-Smale functions $f_j:C_j \\rightarrow \\mathbb{R}$ on the critical submanifolds $C_j$, one can construct a Morse chain complex whose boundary operator is defined by counting cascades \\cite{FraTheA}. Similar data, which also includes a parameter $\\epsilon > 0$ that scales the Morse-Smale functions $f_j$, can be used to define an explicit perturbation of the Morse-Bott function $f$ to a Morse-Smale function $h_\\epsilon:M \\rightarrow \\mathbb{R}$ \\cite{AusMor} \\cite{BanDyn}. In this paper we show that the Morse-Smale-Witten chain complex of $h_\\epsilon$ is the same as the Morse chain complex defined using cascades for any $\\epsilon >0$ sufficiently small. That is, the two chain complexes have the same generators, and their boundary operators are the same (up to a choice of sign). Thus, the Morse Homology Theorem implies that the homology of the casc...

  15. The Cascade is a MMS Instanton

    CERN Document Server

    Evslin, J

    2004-01-01

    Wrap m D5-branes around the 2-cycle of a conifold, place n D3-branes at a point and watch the system relax. The D5-branes source m units of RR 3-form flux on the 3-cycle, which cause dielectric NS5-branes to nucleate and repeatedly sweep out the 3-cycle, each time gaining m units of D3-charge while the stack of D5-branes loses m units of D3-charge. A similar description of the Klebanov-Strassler cascade has been proposed by Kachru, et al. when m>>m-n. Using the T-dual MQCD we argue that the above process occurs for any m and n and in particular may continue for more than one step. The nonbaryonic roots of the SQCD vacua lead to new cascades because, for example, the 3-cycle swept does not link all of the D5's. This decay is the S-dual of a MMS instanton, which is the decay into flux of a brane that is trivial in twisted K-theory. This provides the first evidence for the S-dual of the K-theory classification that does not itself rely upon any strong/weak duality.

  16. Power Grid Defense Against Malicious Cascading Failure

    CERN Document Server

    Shakarian, Paulo; Lindelauf, Roy

    2014-01-01

    An adversary looking to disrupt a power grid may look to target certain substations and sources of power generation to initiate a cascading failure that maximizes the number of customers without electricity. This is particularly an important concern when the enemy has the capability to launch cyber-attacks as practical concerns (i.e. avoiding disruption of service, presence of legacy systems, etc.) may hinder security. Hence, a defender can harden the security posture at certain power stations but may lack the time and resources to do this for the entire power grid. We model a power grid as a graph and introduce the cascading failure game in which both the defender and attacker choose a subset of power stations such as to minimize (maximize) the number of consumers having access to producers of power. We formalize problems for identifying both mixed and deterministic strategies for both players, prove complexity results under a variety of different scenarios, identify tractable cases, and develop algorithms f...

  17. Quaternary Magmatism in the Cascades - Geologic Perspectives

    Science.gov (United States)

    Hildreth, Wes

    2007-01-01

    Foreward The Cascade magmatic arc is a belt of Quaternary volcanoes that extends 1,250 km from Lassen Peak in northern California to Meager Mountain in Canada, above the subduction zone where the Juan de Fuca Plate plunges beneath the North American Plate. This Professional Paper presents a synthesis of the entire volcanic arc, addressing all 2,300 known Quaternary volcanoes, not just the 30 or so visually prominent peaks that comprise the volcanic skyline. Study of Cascade volcanoes goes back to the geological explorers of the late 19th century and the seminal investigations of Howel Williams in the 1920s and 1930s. However, major progress and application of modern scientific methods and instrumentation began only in the 1970s with the advent of systematic geological, geophysical, and geochemical studies of the entire arc. Initial stimulus from the USGS Geothermal Research Program was enhanced by the USGS Volcano Hazards Program following the 1980 eruption of Mount St. Helens. Together, these two USGS Programs have provided more than three decades of stable funding, staffing, and analytical support. This Professional Paper summarizes the resultant USGS data sets and integrates them with the parallel contributions of other investigators. The product is based upon an all-encompassing and definitive geological database, including chemical and isotopic analyses to characterize the rocks and geochronology to provide the critical time constraints. Until now, this massive amount of data has not been summarized, and a systematic and uniform interpretation firmly grounded in geological fact has been lacking. Herein lies the primary utility of this Cascade volume. It not only will be the mandatory starting point for new workers, but also will provide essential geological context to broaden the perspectives of current investigators of specific Cascade volcanoes. Wes Hildreth's insightful understanding of volcanic processes and his uncompromising scientific integrity make him

  18. Updated Global Analysis of the Atmospheric Neutrino Data in terms of neutrino oscillations

    CERN Document Server

    Fornengo, N; Valle, José W F

    2000-01-01

    A global analysis of all the available atmospheric neutrino data is presentedin terms of neutrino oscillations in the nu_mu -> nu_tau and nu_mu -> nu_schannels, where nu_s denotes a sterile neutrino. We perform our analysis of thecontained events data as well as the upward-going neutrino-induced muon fluxes.In addition to the previous data samples of Frejus, Nusex, IMB and Kamiokaexperiments, we include the full data set of the 52 kton-yr ofSuper-Kamiokande, the recent 4.6 kton-yr contained events of Soudan2 and theresults on upgoing muons from the MACRO and Baksan detectors. From thestatistical analysis it emerges that the nu_mu -> nu_tau channel provides thebest agreement with the combined data, with a best fit point of sin^2(2 theta)= 0.99 and Delta m^2 = 3.0 * 10^{-3} eV^2. Although somehow disfavoured, thenu_mu -> nu_s channels cannot be ruled out on the basis of the global fit tothe full set of observables.

  19. Atmospheric Neutrinos

    CERN Document Server

    Gaisser, Thomas K

    2016-01-01

    In view of the observation by IceCube of high-energy astrophysical neutrinos, it is important to quantify the uncertainty in the background of atmospheric neutrinos. There are two sources of uncertainty, the imperfect knowledge of the spectrum and composition of the primary cosmic rays that produce the neutrinos and the limited understanding of hadron production, including charm, at high energy. This paper is an overview of both aspects.

  20. The Orbis Cascade Merger and Its Impact on Patron-Initiated Borrowing

    Science.gov (United States)

    Munson, Doris M.; Milton, Suzanne

    2009-01-01

    In 2000, Eastern Washington University became part of the Cascade Consortium and participated in consortial borrowing through the Cascade Union Catalog. In 2003, the Orbis and Cascade consortia merged into the Orbis Cascade Alliance, which manages the Summit Union Catalog. Since 2000, Cascade or Summit consortial borrowing has increased while…

  1. Terahertz Quantum Cascade Laser Local Oscillator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has a need for airborne or space-based observatories and remote sensors in order to penetrate the opaque atmosphere between 1 and 10 THz. For observations >2...

  2. 36 CFR 7.66 - North Cascades National Park.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false North Cascades National Park. 7.66 Section 7.66 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.66 North Cascades National Park....

  3. Signaling Cascades: Consequences of Varying Substrate and Phosphatase Levels

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Knudsen, Michael; Wiuf, Carsten Henrik

    2012-01-01

    We study signaling cascades with an arbitrary number of layers of one-site phosphorylation cycles. Such cascades are abundant in nature and integrated parts of many pathways. Based on the Michaelis-Menten model of enzyme kinetics and the law of mass-action, we derive explicit analytic expressions...

  4. Cascade algorithm and multiresolution analysis on the Heisenberg group

    Institute of Scientific and Technical Information of China (English)

    LIU Heping; LIU Yu; PENG Lizhong; CHU Xiaoyong

    2005-01-01

    In this paper we investigate the relationship between the convergence of cascade algorithm and orthogonal (or biorthogonal) multiresolution analysis on the Heisenberg group. It is proved that the (strong) convergence of cascade algorithm together with the perfect reconstruction condition induces an orthogonal multiresolution analysis and vice versa. Similar results are also proved for biorthogonal multiresolution analysis.

  5. Cascade vulnerability for risk analysis of water infrastructure.

    Science.gov (United States)

    Sitzenfrei, R; Mair, M; Möderl, M; Rauch, W

    2011-01-01

    One of the major tasks in urban water management is failure-free operation for at least most of the time. Accordingly, the reliability of the network systems in urban water management has a crucial role. The failure of a component in these systems impacts potable water distribution and urban drainage. Therefore, water distribution and urban drainage systems are categorized as critical infrastructure. Vulnerability is the degree to which a system is likely to experience harm induced by perturbation or stress. However, for risk assessment, we usually assume that events and failures are singular and independent, i.e. several simultaneous events and cascading events are unconsidered. Although failures can be causally linked, a simultaneous consideration in risk analysis is hardly considered. To close this gap, this work introduces the term cascade vulnerability for water infrastructure. Cascade vulnerability accounts for cascading and simultaneous events. Following this definition, cascade risk maps are a merger of hazard and cascade vulnerability maps. In this work cascade vulnerability maps for water distribution systems and urban drainage systems based on the 'Achilles-Approach' are introduced and discussed. It is shown, that neglecting cascading effects results in significant underestimation of risk scenarios.

  6. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    Directory of Open Access Journals (Sweden)

    J. Lepicovsky

    2004-01-01

    velocity.To date, this flow behavior has only been observed in a linear transonic cascade. Further research is necessary to confirm this phenomenon occurs in actual transonic fans and is not the by-product of an endwall restricted linear cascade.

  7. A simple model of global cascades on random networks

    Science.gov (United States)

    Watts, Duncan J.

    2002-04-01

    The origin of large but rare cascades that are triggered by small initial shocks is a phenomenon that manifests itself as diversely as cultural fads, collective action, the diffusion of norms and innovations, and cascading failures in infrastructure and organizational networks. This paper presents a possible explanation of this phenomenon in terms of a sparse, random network of interacting agents whose decisions are determined by the actions of their neighbors according to a simple threshold rule. Two regimes are identified in which the network is susceptible to very large cascadesherein called global cascadesthat occur very rarely. When cascade propagation is limited by the connectivity of the network, a power law distribution of cascade sizes is observed, analogous to the cluster size distribution in standard percolation theory and avalanches in self-organized criticality. But when the network is highly connected, cascade propagation is limited instead by the local stability of the nodes themselves, and the size distribution of cascades is bimodal, implying a more extreme kind of instability that is correspondingly harder to anticipate. In the first regime, where the distribution of network neighbors is highly skewed, it is found that the most connected nodes are far more likely than average nodes to trigger cascades, but not in the second regime. Finally, it is shown that heterogeneity plays an ambiguous role in determining a system's stability: increasingly heterogeneous thresholds make the system more vulnerable to global cascades; but an increasingly heterogeneous degree distribution makes it less vulnerable.

  8. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  9. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  10. Temporal switching induced by cascaded third order nonlinearity

    DEFF Research Database (Denmark)

    Eilenberger, Falk; Bache, Morten; Minardi, Stefano;

    2012-01-01

    We investigate the impact of cascaded third harmonic generation and the intrinsic n4 material nonlinearity on the propagation of ultrashort pulses in noble-gas filled Kagome fibers. We show that the pressure tunability of the cascade allows for the implementation of temporal switching. We also...

  11. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    Energy Technology Data Exchange (ETDEWEB)

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  12. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    . As a response to this situation, our design artefact, the interactive furniture Kidkit, invites children to become accustomed to the alarming sounds sampled from the ward while they are waiting in the waiting room. Our design acknowledges how atmospheres emerge as temporal negotiations between the rhythms......, a familiar relationship with the alarming sounds in the ward, enabling her to focus later more on the visit with the relative. The article discusses the proposed design strategy behind this solution and the potentiality for its use in hospital environments in general....

  13. Novel trophic cascades: apex predators enable coexistence.

    Science.gov (United States)

    Wallach, Arian D; Ripple, William J; Carroll, Scott P

    2015-03-01

    Novel assemblages of native and introduced species characterize a growing proportion of ecosystems worldwide. Some introduced species have contributed to extinctions, even extinction waves, spurring widespread efforts to eradicate or control them. We propose that trophic cascade theory offers insights into why introduced species sometimes become harmful, but in other cases stably coexist with natives and offer net benefits. Large predators commonly limit populations of potentially irruptive prey and mesopredators, both native and introduced. This top-down force influences a wide range of ecosystem processes that often enhance biodiversity. We argue that many species, regardless of their origin or priors, are allies for the retention and restoration of biodiversity in top-down regulated ecosystems.

  14. Exact coherent structures for the turbulent cascade

    Science.gov (United States)

    Eckhardt, Bruno; Zammert, Stefan

    2016-11-01

    The exact coherent structures that are connected with the transition to turbulence in interior flows usually extend across the full height of the domain. Using exact coherent states that are localized in the shear direction together with scaling ideas for the Navier-Stokes equation that combine length and Reynolds number, we show how such large scale structures can be morphed into smaller scale coherent structures. As the Reynolds number increases, more of these states with ever smaller scales appear, all the way down to the Kolmogorov scale. We present the structure and dynamical properties of several families of exact coherent solution in plane Couette flow, with different degrees of spatial localization: Some of them remain localized in the center and help to built the turbulence cascade, others are localized near the walls and contribute to shaping the boundary layer profile.

  15. Mechanical gating of a mechanochemical reaction cascade

    Science.gov (United States)

    Wang, Junpeng; Kouznetsova, Tatiana B.; Boulatov, Roman; Craig, Stephen L.

    2016-11-01

    Covalent polymer mechanochemistry offers promising opportunities for the control and engineering of reactivity. To date, covalent mechanochemistry has largely been limited to individual reactions, but it also presents potential for intricate reaction systems and feedback loops. Here we report a molecular architecture, in which a cyclobutane mechanophore functions as a gate to regulate the activation of a second mechanophore, dichlorocyclopropane, resulting in a mechanochemical cascade reaction. Single-molecule force spectroscopy, pulsed ultrasonication experiments and DFT-level calculations support gating and indicate that extra force of >0.5 nN needs to be applied to a polymer of gated gDCC than of free gDCC for the mechanochemical isomerization gDCC to proceed at equal rate. The gating concept provides a mechanism by which to regulate stress-responsive behaviours, such as load-strengthening and mechanochromism, in future materials designs.

  16. Electrical derivative measurement of quantum cascade lasers

    Science.gov (United States)

    Guo, Dingkai; Cheng, Liwei; Chen, Xing; Choa, Fow-Sen; Fan, Jenyu; Worchesky, Terry

    2011-02-01

    The electrical derivative characteristics of quantum cascade lasers (QCLs) are investigated to test the QCL threshold, leakage current, and possibly explore carrier transport. QCL thresholds can be identified by searching for the slope peak of the first derivative of the I-V curves and can be further confirmed with its alignment to the peak of the second derivative of the I-V curves. Leakage current in QCLs with oxide-blocked ridge waveguides and buried heterostructure (BH) waveguides are studied and compared. The oxide-blocking structures provide the lowest leakage current although the capped-mesa-BH (CMBH) QCLs provide the toughest durability under highly stressful operations. The leakage current of CMBH QCLs are also compared at different temperatures.

  17. Free energy cascade in gyrokinetic turbulence

    CERN Document Server

    Navarro, A Bañón; Albrecht-Marc, M; Merz, F; Görler, T; Jenko, F; Carati, D

    2010-01-01

    In gyrokinetic theory, the quadratic nonlinearity is known to play an important role in the dynamics by redistributing (in a conservative fashion) the free energy between the various active scales. In the present study, the free energy transfer is analyzed for the case of ion temperature gradient driven turbulence. It is shown that it shares many properties with the energy transfer in fluid turbulence. In particular, one finds a forward (from large to small scales), extremely local, and self-similar cascade of free energy in the plane perpendicular to the background magnetic field. These findings shed light on some fundamental properties of plasma turbulence, and encourage the development of large eddy simulation techniques for gyrokinetics.

  18. Research on Cascaded H-bridge SVG

    Directory of Open Access Journals (Sweden)

    Yannan Yu

    2014-07-01

    Full Text Available Due to the sharp increase of the non-linear loads, the power quality lagged behind the need for an adequate power system. With a fast response, low loss, low output harmonic current, SVG has become the mainstream of dynamic reactive power compensation devices. The paper introduces a multilevel cascaded H-bridge SVG, featured with DSP+FPGA dual-core control unit and fault-tolerant redundant system, which will enhance the reliability and dynamic response, reduce the switching loss and equipment cost, and increase the efficiency of the reactive power compensation. Through instructing the MATLAB simulation model of SVG and testing model machine, the design correction of medium voltage SVG power circuits and parameters is verified. The model machine is working well.

  19. Congestion and cascades in payment systems

    Science.gov (United States)

    Beyeler, Walter E.; Glass, Robert J.; Bech, Morten L.; Soramäki, Kimmo

    2007-10-01

    We develop a parsimonious model of the interbank payment system. The model incorporates an endogenous instruction arrival process, a scale-free topology of payments between banks, a fixed total liquidity which limits banks’ capacity to process arriving instructions, and a global market that distributes liquidity. We find that at low liquidity the system becomes congested and payment settlement loses correlation with payment instruction arrival, becoming coupled across the network. The onset of congestion is evidently related to the relative values of three characteristic times: the time for banks’ net position to return to 0, the time for a bank to exhaust its liquidity endowment, and the liquidity market relaxation time. In the congested regime settlement takes place in cascades having a characteristic length scale. A global liquidity market substantially attenuates congestion, requiring only a small fraction of the payment-induced liquidity flow to achieve strong beneficial effects.

  20. Cascading Node Failure with Continuous States in Random Geometric Networks

    CERN Document Server

    Kamran, Khashayar

    2016-01-01

    The increasing complexity and interdependency of today's networks highlight the importance of studying network robustness to failure and attacks. Many large-scale networks are prone to cascading effects where a limited number of initial failures (due to attacks, natural hazards or resource depletion) propagate through a dependent mechanism, ultimately leading to a global failure scenario where a substantial fraction of the network loses its functionality. These cascading failure scenarios often take place in networks which are embedded in space and constrained by geometry. Building on previous results on cascading failure in random geometric networks, we introduce and analyze a continuous cascading failure model where a node has an initial continuously-valued state, and fails if the aggregate state of its neighbors fall below a threshold. Within this model, we derive analytical conditions for the occurrence and non-occurrence of cascading node failure, respectively.

  1. Tolerance of edge cascades with coupled map lattices methods

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zheng Jian-Feng

    2009-01-01

    This paper studies the cascading failure on random networks and scale-free networks by introducing the tolerance parameter of edge based on the coupled map lattices methods. The whole work focuses on investigating some indices including the number of failed edges, dynamic edge tolerance capacity and the perturbation of edge. In general, it assumes that the perturbation is attributed to the normal distribution in adopted simulations. By investigating the effectiveness of edge tolerance in scale-free and random networks, it finds that the larger tolerance parameter 位 can more efficiently delay the cascading failure process for scale-free networks than random networks. These results indicate that the cascading failure process can be effectively controlled by increasing the tolerance parameter A. Moreover, the simulations also show that, larger variance of perturbation can easily trigger the cascading failures than the smaller one. This study may be useful for evaluating efficiency of whole traffic systems, and for alleviating cascading failure in such systems.

  2. A modeling framework for system restoration from cascading failures.

    Science.gov (United States)

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  3. Fluctuation sensitivity of a transcriptional signaling cascade

    Science.gov (United States)

    Pilkiewicz, Kevin R.; Mayo, Michael L.

    2016-09-01

    The internal biochemical state of a cell is regulated by a vast transcriptional network that kinetically correlates the concentrations of numerous proteins. Fluctuations in protein concentration that encode crucial information about this changing state must compete with fluctuations caused by the noisy cellular environment in order to successfully transmit information across the network. Oftentimes, one protein must regulate another through a sequence of intermediaries, and conventional wisdom, derived from the data processing inequality of information theory, leads us to expect that longer sequences should lose more information to noise. Using the metric of mutual information to characterize the fluctuation sensitivity of transcriptional signaling cascades, we find, counter to this expectation, that longer chains of regulatory interactions can instead lead to enhanced informational efficiency. We derive an analytic expression for the mutual information from a generalized chemical kinetics model that we reduce to simple, mass-action kinetics by linearizing for small fluctuations about the basal biological steady state, and we find that at long times this expression depends only on a simple ratio of protein production to destruction rates and the length of the cascade. We place bounds on the values of these parameters by requiring that the mutual information be at least one bit—otherwise, any received signal would be indistinguishable from noise—and we find not only that nature has devised a way to circumvent the data processing inequality, but that it must be circumvented to attain this one-bit threshold. We demonstrate how this result places informational and biochemical efficiency at odds with one another by correlating high transcription factor binding affinities with low informational output, and we conclude with an analysis of the validity of our assumptions and propose how they might be tested experimentally.

  4. 3D Effects in the Formation of Zonal Jets Through Inverse Cascade

    Science.gov (United States)

    Sayanagi, K. M.; Showman, A. P.

    2006-12-01

    The atmospheric zonal jets on Jupiter and Saturn are characterized by the broad, prograde, equatorial jet and the narrower, higher-latitude jets that alternate between prograde and retrograde. The question of what controls the widths and directions of those jets remains a major unsolved problem in geophysical fluid dynamics. Past studies have shown that, in shallow flows on a rotating sphere, small random vortices can undergo inverse cascade to form zonal jets with a characteristic width called the Rhines scale. Most of the studies to date use 2D non-divergent or shallow-water models in studying this zonal jet formation mechanism. However, in the parameter ranges representative of the Jovian conditions, the flows produced by 2D non- divergent models are typically dominated by strong circumpolar jets, and the shallow-water models produce a robust retrograde equatorial jet. These models' apparent inabilities in reproducing some key Jovian jet features may suggest the importance of 3D effects in controlling the jets' large-scale horizontal structures. To date, Kitamura and Matsuda (Fluid Dynamics Research, 34, 33-57, 2004) is the only published study that analyzes the 3D effects in the zonalization of fine-scale random turbulence through the inverse cascade. Their two-layer primitive equation simulations of free-evolving flows resulted in circumpolar jet dominated flows, although slower mid-latitude jets are also present. Our study is a significant extension over that by Kitamura and Matsuda and includes substantially more layers to study the zonalization process to more fully resolve relevant 3D effects in the inverse cascade. We test the flow behavior's dependence on the deformation radius and the resulting vertical structures in both spherical and beta-plane geometries. Our study uses the Explicit Planetary Isentropic Coordinate (EPIC) model (Dowling et al, Icarus, 32, 221-238., 1998). The research is supported by a NASA Planetary Atmospheres grant to APS.

  5. Influence of the condensate and inverse cascade on the direct cascade in wave turbulence

    CERN Document Server

    Korotkevich, A O

    2009-01-01

    During direct numerical simulation of the isotropic turbulence of surface gravity waves in the framework of Hamiltonian equations formation of the long wave background or condensate was observed. Exponents of the direct cascade spectra at the different levels of an artificial condensate suppression show a tendency to become closer to the prediction of the wave turbulence theory at lower levels of condensate. A simple qualitative explanation of the mechanism of this phenomenon is proposed.

  6. Energy spectra and passive tracer cascades in turbulent flows

    CERN Document Server

    Jolly, Michael

    2016-01-01

    We study the influence of the energy spectrum on the extent of the cascade range of a passive tracer in turbulent flows. The interesting cases are when there are two different spectra over the potential range of the tracer cascade (in 2D when the tracer forcing is in the inverse energy cascade range, and in 3D when the Schmidt number Sc is large). The extent of the tracer cascade range is then limited by the width of the range for the shallower of the two energy spectra. Nevertheless, we show that in dimension $d=2,3$ the tracer cascade range extends (up to a logarithm) to $\\kappa_{d\\text{D}}^{p}$, where $\\kappa_{d\\text{D}}$ is the wavenumber beyond which diffusion should dominate and $p$ is arbitrarily close to 1, provided Sc is larger than a certain power (depending on $p$) of the Grashof number. We also derive estimates which suggest that in 2D, for Sc${}\\sim1$ a wide tracer cascade can coexist with a significant inverse energy cascade at Grashof numbers large enough to produce a turbulent flow.

  7. Out of control: Fluctuation of cascading dynamics in networks

    Science.gov (United States)

    Wang, Jianwei; Cai, Lin; Xu, Bo; Li, Peng; Sun, Enhui; Zhu, Zhiguo

    2016-11-01

    Applying two preferential selection mechanisms of flow destination, we develop two new methods to quantify the initial load of a node, where the flow is transported along the shortest path between two nodes. We propose a simple cascading model and study cascading dynamics induced by attacking the node with the highest load in some synthetic and actual networks. Surprisingly, we observe the abnormal fluctuation of cascading dynamics, i.e., more damage can be triggered if we spend significantly higher cost to protect a network. In particular, this phenomenon is independent of the initial flow distribution and the preferential selection mechanisms of flow destination. However, it remains unclear which specific structural patterns may affect the fluctuation of cascading dynamics. In this paper, we examine the local evolution of the cascading propagation by constructing some special networks. We show that revivals of some nodes in the double ring structure facilitate the transportation of the flow between two unconnected sub-networks, cause more damage and subsequently lead to the abnormal fluctuation of cascading dynamics. Compared with the traditional definition of the betweenness, we adopt two new proposed methods to further evaluate the resilience of several actual networks. We find that some real world networks reach the strongest resilience level against cascading failures in our preferential selection mechanisms of flow destination. Moreover, we explore how to use the minimum cost to maximize the resilience of the studied networks.

  8. Factors Associated with PMTCT Cascade Completion in Four African Countries

    Directory of Open Access Journals (Sweden)

    Jodie Dionne-Odom

    2016-01-01

    Full Text Available Background. Many countries are working to reduce or eliminate mother-to-child transmission (MTCT of HIV. Prevention efforts have been conceptualized as steps in a cascade but cascade completion rates during and after pregnancy are low. Methods. A cross-sectional survey was performed across 26 communities in Cameroon, Cote d’Ivoire, South Africa, and Zambia. Women who reported a pregnancy within two years were enrolled. Participant responses were used to construct the PMTCT cascade with all of the following steps required for completion: at least one antenatal visit, HIV testing performed, HIV testing result received, initiation of maternal prophylaxis, and initiation of infant prophylaxis. Factors associated with cascade completion were identified using multivariable logistic regression modeling. Results. Of 976 HIV-infected women, only 355 (36.4% completed the PMTCT cascade. Although most women (69.2% did not know their partner’s HIV status; awareness of partner HIV status was associated with cascade completion (aOR 1.4, 95% CI 1.01–2.0. Completion was also associated with receiving an HIV diagnosis prior to pregnancy compared with HIV diagnosis during or after pregnancy (aOR 14.1, 95% CI 5.2–38.6. Conclusions. Pregnant women with HIV infection in Africa who were aware of their partner’s HIV status and who were diagnosed with HIV before pregnancy were more likely to complete the PMTCT cascade.

  9. Reduce of Threshold of Laser Inducing Breakdown in Atmosphere by Introducing an Electric Spark

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-Bin; SHI Wei; LI Hua

    2005-01-01

    @@ We report laser-generated plasmas in atmosphere with electrical spark generated by a synchronization circuit.The breakdown thresholds under the conditions that the electrical spark is used and not used are compared.The breakdown threshold has a distinct decrease after the electrical spark is used. Breakdown thresholds as afunction of atmosphere pressure have also been measured at laser wavelengths 532nm and 1064 nm for the laserpulse width of 15ns. We also discuss the principle and performances of the ionized atmosphere by Nd:YAGlaser under the condition of electrical spark introduction. Multiphoton ionization and cascade ionization playimportant roles in the whole process of atmosphere ionization. The free electron induced by electrical spark cansupply the initialization free electron number for multiphoton ionization and cascade ionization. A model forbreakdown in atmosphere, which is in good agreement with the experimental results, is described.

  10. Blind Deconvolution in Nonminimum Phase Systems Using Cascade Structure

    Directory of Open Access Journals (Sweden)

    Liqing Zhang

    2007-01-01

    Full Text Available We introduce a novel cascade demixing structure for multichannel blind deconvolution in nonminimum phase systems. To simplify the learning process, we decompose the demixing model into a causal finite impulse response (FIR filter and an anticausal scalar FIR filter. A permutable cascade structure is constructed by two subfilters. After discussing geometrical structure of FIR filter manifold, we develop the natural gradient algorithms for both FIR subfilters. Furthermore, we derive the stability conditions of algorithms using the permutable characteristic of the cascade structure. Finally, computer simulations are provided to show good learning performance of the proposed method.

  11. An Improved Phase Disposition SPWM Strategy for Cascaded Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Jinbang Xu

    2014-01-01

    Full Text Available The Carrier Phase Shifted (CPS strategy is conventional for cascaded multilevel inverter, because it can naturally ensure all cascaded cells to output balanced power. However, in point of spectra of the output line voltage, CPS is suboptimal to Phase Disposition (PD strategy, because the latter can not naturally ensure power balance. This paper presents an improved PD strategy, inspiration from the disposition of CPS strategy triangle carriers. Just reconstructing the triangle carriers of PD strategy, it can not only reserve the waveform quality of the line voltage to be optimal, but also naturally ensure the output power of each cascaded cells to be balanced.

  12. Probabilistic analysis of cascade failure dynamics in complex network

    Science.gov (United States)

    Zhang, Ding-Xue; Zhao, Dan; Guan, Zhi-Hong; Wu, Yonghong; Chi, Ming; Zheng, Gui-Lin

    2016-11-01

    The impact of initial load and tolerance parameter distribution on cascade failure is investigated. By using mean field theory, a probabilistic cascade failure model is established. Based on the model, the damage caused by certain attack size can be predicted, and the critical attack size is derived by the condition of cascade failure end, which ensures no collapse. The critical attack size is larger than the case of constant tolerance parameter for network of random distribution. Comparing three typical distributions, simulation results indicate that the network whose initial load and tolerance parameter both follow Weibull distribution performs better than others.

  13. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

  14. Cascade category-aware visual search.

    Science.gov (United States)

    Zhang, Shiliang; Tian, Qi; Huang, Qingming; Gao, Wen; Rui, Yong

    2014-06-01

    Incorporating image classification into image retrieval system brings many attractive advantages. For instance, the search space can be narrowed down by rejecting images in irrelevant categories of the query. The retrieved images can be more consistent in semantics by indexing and returning images in the relevant categories together. However, due to their different goals on recognition accuracy and retrieval scalability, it is hard to efficiently incorporate most image classification works into large-scale image search. To study this problem, we propose cascade category-aware visual search, which utilizes weak category clue to achieve better retrieval accuracy, efficiency, and memory consumption. To capture the category and visual clues of an image, we first learn category-visual words, which are discriminative and repeatable local features labeled with categories. By identifying category-visual words in database images, we are able to discard noisy local features and extract image visual and category clues, which are hence recorded in a hierarchical index structure. Our retrieval system narrows down the search space by: 1) filtering the noisy local features in query; 2) rejecting irrelevant categories in database; and 3) preforming discriminative visual search in relevant categories. The proposed algorithm is tested on object search, landmark search, and large-scale similar image search on the large-scale LSVRC10 data set. Although the category clue introduced is weak, our algorithm still shows substantial advantages in retrieval accuracy, efficiency, and memory consumption than the state-of-the-art.

  15. Probing the energy cascade of convective turbulence.

    Science.gov (United States)

    Kunnen, R P J; Clercx, H J H

    2014-12-01

    The existence of a buoyancy-dominated scaling range in convective turbulence is a longstanding open question. We investigate this issue by considering the scale-by-scale energy budget in direct numerical simulations of Rayleigh-Bénard convection. We try to minimize the so-called Bolgiano length scale, the length scale at which buoyancy becomes dominant for scaling. Therefore, we deliberately choose modest Rayleigh numbers Ra=2.5×10(6) and 2.5×10(7). The budget reveals that buoyant forcing, turbulent energy transfer, and dissipation are contributing significantly over a wide range of scales. Thereby neither Kolmogorov-like (balance of turbulent transfer and dissipation) nor Bolgiano-Obukhov-like scaling (balance of turbulent transfer and buoyancy) is expected in the structure functions, which indeed reveal inconclusive scaling behavior. Furthermore, we consider the calculation of the Bolgiano length scale. To account for correlations between the dissipation rates of kinetic energy and thermal variance we propose to average the Bolgiano length scale directly. This gives an estimate, which is one order of magnitude larger than the previous estimate, and actually larger than the domain itself. Rather than studying the scaling of structure functions, we propose that the use of scale-by-scale energy budgets resolving anisotropic contributions is appropriate to consider the energy cascade mechanisms in turbulent convection.

  16. Cascading reminiscence bumps in popular music.

    Science.gov (United States)

    Krumhansl, Carol Lynne; Zupnick, Justin Adam

    2013-10-01

    Autobiographical memories are disproportionately recalled for events in late adolescence and early adulthood, a phenomenon called the reminiscence bump. Previous studies on music have found autobiographical memories and life-long preferences for music from this period. In the present study, we probed young adults' personal memories associated with top hits over 5-and-a-half decades, as well as the context of their memories and their recognition of, preference for, quality judgments of, and emotional reactions to that music. All these measures showed the typical increase for music released during the two decades of their lives. Unexpectedly, we found that the same measures peaked for the music of participants' parents' generation. This finding points to the impact of music in childhood and suggests that these results reflect the prevalence of music in the home environment. An earlier peak occurred for 1960s music, which may be explained by its quality or by its transmission through two generations. We refer to this pattern of musical cultural transmission over generations as cascading reminiscence bumps.

  17. Optimization Issues in a Harmonic Cascade FEL

    CERN Document Server

    De Ninno, G

    2005-01-01

    Presently there is significant interest by multiple groups (e.g. BNL, ELETTRA, LBNL, BESSY, MIT) to reach short output wavelengths via a harmonic cascade FEL using an external seed laser. In a multistage device, there are a number of "free" parameters such as the nominal power of the input seed, the lengths of the individual modulator and radiator undulators, the strengths (i.e. the R56's) of the dispersive sections, the choice of the actual harmonic numbers to reach a given wavelength, etc., whose optimization is a non-trivial exercise. In particular, one can choose whether to operate predominantly in the "high gain" regime such as was proposed by Yu [1] in which case each radiator undulator is many gain lengths long or, alternatively, in the "low gain" regime in which case all undulators (except possibly the last radiator) are a couple gain lengths or less long and the output from each radiator essentially corresponds to coherent spontaneous emission from a pre-bunched beam. With particular emphasis upon th...

  18. Astronomical Forcing of Salt Marsh Biogeochemical Cascades

    Science.gov (United States)

    Morris, J. T.; Sundberg, K.

    2008-12-01

    Astronomically forced changes in the hydroperiod of a salt marsh affect the rate of marsh primary production leading to a biogeochemical cascade. For example, salt marsh primary production and biogeochemical cycles in coastal salt marshes are sensitive to the 18.6-year lunar nodal cycle, which alters the tidal amplitude by about 5 cm. For marshes that are perched high in the tidal frame, a relatively small increase in tidal amplitude and flooding lowers sediment salinity and stimulates primary production. Porewater sulfide concentrations are positively correlated with tidal amplitude and vary on the same cycle as primary production. Soluble reactive phosphate and ammonium concentrations in pore water also vary on this 18.6- year cycle. Phosphate likely responds to variation in the reaction of sulfide with iron-phosphate compounds, while the production of ammonium in sediments is coupled to the activity of diazotrophs that are carbon- limited and, therefore, are regulated by primary productivity. Ammonium also would accumulate when sulfides block nitrification. These dependencies work as a positive feedback between primary production and nutrient supply and are predictive of the near-term effects of sea-level rise.

  19. Quantum cascade laser Kerr frequency comb

    CERN Document Server

    Lecaplain, Caroline; Lucas, Erwan; Jost, John D; Kippenberg, Tobias J

    2015-01-01

    The mid-infrared (mid-IR) regime (typically the wavelength regime of $\\lambda \\sim 2.5-20 \\ \\mathrm{\\mu m}$) is an important spectral range for spectroscopy as many molecules have their fundamental rotational-vibrational absorption in this band. Recently optical frequency combs based on optical microresonators ("Kerr" combs) at the onset of the mid-IR region have been generated using crystalline resonators and integrated planar silicon micro-resonators. Here we extend for the first time Kerr combs deep into the mid-IR i.e. the 'molecular fingerprint' region. This is achieved by combining an ultra high quality (Q) factor mid-IR microresonator based on crystalline $\\mathrm{MgF_{2}}$ with the quantum cascade laser (QCL) technology. Using a tapered chalgogenide (ChG) fiber and a QCL continuous wave pump laser, frequency combs at $\\lambda\\sim 4.4\\ \\mathrm{\\mu m}$ (i.e. 2270cm$^{-1}$) are generated, that span over 600nm (i.e. 300cm$^{-1}$) in bandwidth, with a mode spacing of 14.3GHz (0.5cm$^{-1}$), corresponding t...

  20. Magnetic reconnection from a multiscale instability cascade.

    Science.gov (United States)

    Moser, Auna L; Bellan, Paul M

    2012-02-15

    Magnetic reconnection, the process whereby magnetic field lines break and then reconnect to form a different topology, underlies critical dynamics of magnetically confined plasmas in both nature and the laboratory. Magnetic reconnection involves localized diffusion of the magnetic field across plasma, yet observed reconnection rates are typically much higher than can be accounted for using classical electrical resistivity. It is generally proposed that the field diffusion underlying fast reconnection results instead from some combination of non-magnetohydrodynamic processes that become important on the 'microscopic' scale of the ion Larmor radius or the ion skin depth. A recent laboratory experiment demonstrated a transition from slow to fast magnetic reconnection when a current channel narrowed to a microscopic scale, but did not address how a macroscopic magnetohydrodynamic system accesses the microscale. Recent theoretical models and numerical simulations suggest that a macroscopic, two-dimensional magnetohydrodynamic current sheet might do this through a sequence of repetitive tearing and thinning into two-dimensional magnetized plasma structures having successively finer scales. Here we report observations demonstrating a cascade of instabilities from a distinct, macroscopic-scale magnetohydrodynamic instability to a distinct, microscopic-scale (ion skin depth) instability associated with fast magnetic reconnection. These observations resolve the full three-dimensional dynamics and give insight into the frequently impulsive nature of reconnection in space and laboratory plasmas.

  1. Compression-absorption cascade refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Sieres, Jaime; Vazquez, Manuel [Area de Maquinas y Motores Termicos, Escuela Tecnica Superior de Ingenieros Industriales, Universidade de Vigo, Campus Lagoas-Marcosende, 9, 36200 Vigo (Spain)

    2006-04-01

    This paper describes the study carried out to analyse a refrigeration system in cascade with a compression system at the low temperature stage and an absorption system at the high temperature stage to generate cooling at low temperatures, as well as the possibility of powering it by means of a cogeneration system. CO{sub 2} and NH{sub 3} have been considered as refrigerants in the compression stage and the pair NH{sub 3}-H{sub 2}O in the absorption stage. The analysis has been realized by means of a mathematical model of the refrigeration system implemented in a computer program and taking into account the characteristic operating conditions of a cogeneration system with gas engines. The paper presents the results obtained regarding the performance of the refrigeration system and the adaptability between the power requirements of the refrigeration system and the power supplied by the cogeneration system taking into account the present Spanish Regulations about the use of cogeneration systems. [Author].

  2. Cascading failures in local-world evolving networks

    Institute of Scientific and Technical Information of China (English)

    Zhe-jing BAO; Yi-jia CAO

    2008-01-01

    The local-world (LW) evolving network model shows a transition for the degree distribution between the exponential and power-law distributions, depending on the LW size. Cascading failures under intentional attacks in LW network models with different LW sizes were investigated using the cascading failures load model. We found that the LW size has a significant impact on the network's robustness against deliberate attacks. It is much easier to trigger cascading failures in LW evolving networks with a larger LW size. Therefore, to avoid cascading failures in real networks with local preferential attachment such as the Internet, the World Trade Web and the multi-agent system, the LW size should be as small as possible.

  3. Influence of Blade Chordwise Lean on Development of Cascade Losses

    Institute of Scientific and Technical Information of China (English)

    HanWanjin; HuangHongyan; 等

    1996-01-01

    An experimetal investigation was carried out on the effect of blade chordwise lean on the losse in highly loaded rectangular turbine cascades,Datailed measurements include 10 traverses from upstream to downstream of the cascades with five-hole spherical probes.Compared with the experimental data of the coventional Straight and pitchwise lean blades under the same conditions,it is shown that the effect of chordwise lean on the development of the cascade losses is similar to that of pitchwise lean.However,the chordwise lean produces smaller streamwise adverse pressure gradients near both endwalls and a smaller spanwise negative one starting from the actute angle side in the first part of the passages in chordwise lean cascade,thereby the saddle point separations and intensities of the passage vortices are weakened and the secondary vorte losses are cut down notably.

  4. Statistical analysis of cascading failures in power grids

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Pfitzner, Rene [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory

    2010-12-01

    We introduce a new microscopic model of cascading failures in transmission power grids. This model accounts for automatic response of the grid to load fluctuations that take place on the scale of minutes, when optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, caused by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systems consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascading outages over real-world power networks are discussed.

  5. Enantiomer separation in a cascaded micellar-enhanced ultrafiltration system

    NARCIS (Netherlands)

    Overdevest, P.E.M.; Hoenders, M.H.J.; Riet, van 't K.; Padt, van der A.; Keurentjes, J.T.F.

    2002-01-01

    The increasing demand for optically pure compounds (enantiomers) stimulates the development of new enantiomer separation processes on an industrial scale. The separation of enantiomers by ultrafiltration of enantioselective micelles was studied in a cascaded system. The feasibility of this separatio

  6. Terahertz Quantum Cascade Laser Based 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  7. Mutually independent cascades in anisotropic soap-film turbulence

    Science.gov (United States)

    Liu, Chien-Chia; Gioia, Gustavo; Chakraborty, Pinaki

    2015-03-01

    Computational, experimental and field data amassed to date indicate that in 2D turbulence the spectrum of longitudinal velocity fluctuations, E11 (k1) , and the spectrum of transverse velocity fluctuations, E22 (k1) , correspond always to the same cascade, consistent with isotropy, so that E11 (k1) ~k-α and E22 (k1) ~k-α , where the ``spectral exponent'' α is either 5/3 (for the inverse-energy cascade) or 3 (for the enstrophy cascade). Here, we carry out experiments on turbulent 2D soap-film flows in which E11 (k1) ~k - 5 / 3 and E22 (k1) ~k-3 , as if two mutually independent cascades were concurrently active within the same flow. To our knowledge, this species of spectrum has never been observed or predicted theoretically. Our finding might open up new vistas in the understanding of turbulence.

  8. Vulnerability and Cosusceptibility Determine the Size of Network Cascades

    Science.gov (United States)

    Yang, Yang; Nishikawa, Takashi; Motter, Adilson E.

    2017-01-01

    In a network, a local disturbance can propagate and eventually cause a substantial part of the system to fail in cascade events that are easy to conceptualize but extraordinarily difficult to predict. Here, we develop a statistical framework that can predict cascade size distributions by incorporating two ingredients only: the vulnerability of individual components and the cosusceptibility of groups of components (i.e., their tendency to fail together). Using cascades in power grids as a representative example, we show that correlations between component failures define structured and often surprisingly large groups of cosusceptible components. Aside from their implications for blackout studies, these results provide insights and a new modeling framework for understanding cascades in financial systems, food webs, and complex networks in general.

  9. Electron-positron cascades in multiple-laser optical traps

    Science.gov (United States)

    Vranic, Marija; Grismayer, Thomas; Fonseca, Ricardo A.; Silva, Luis O.

    2017-01-01

    We present an analytical and numerical study of multiple-laser QED cascades induced with linearly polarised laser pulses. We analyse different polarisation orientations and propose a configuration that maximises cascade multiplicity and favours laser absorption. We generalise the analytical estimate for the cascade growth rate previously calculated in the field of two colliding linearly polarised laser pulses and account for multiple laser interaction. The estimate is verified by a comprehensive numerical study of four-laser QED cascades across a range of different laser intensities with QED PIC module of OSIRIS. We show that by using four linearly polarised 30 fs laser pulses, one can convert more than 50% of the total energy to gamma-rays at laser intensity I≃ {{10}24}~\\text{W}~\\text{c}{{\\text{m}}-2} . In this configuration, the laser conversion efficiency is higher compared with the case with two colliding lasers.

  10. Cascade Structure of Digital Predistorter for Power Amplifier Linearization

    Directory of Open Access Journals (Sweden)

    E. B. Solovyeva

    2015-12-01

    Full Text Available In this paper, a cascade structure of nonlinear digital predistorter (DPD synthesized by the direct learning adaptive algorithm is represented. DPD is used for linearization of power amplifier (PA characteristic, namely for compensation of PA nonlinear distortion. Blocks of the cascade DPD are described by different models: the functional link artificial neural network (FLANN, the polynomial perceptron network (PPN and the radially pruned Volterra model (RPVM. At synthesis of the cascade DPD there is possibility to overcome the ill conditionality problem due to reducing the dimension of DPD nonlinear operator approximation. Results of compensating nonlinear distortion in Wiener–Hammerstein model of PA at the GSM–signal with four carriers are shown. The highest accuracy of PA linearization is produced by the cascade DPD containing PPN and RPVM.

  11. Noise properties and cascadability of SOA-EA regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne;

    2002-01-01

    We suggest and analyse a new device containing concatenated pairs of semiconductor optical amplifiers (SOAs) and electroabsorption modulators (EAs). The device has regenerative properties and improves the cascadability of optical fibre links....

  12. Dynamic Modeling of Cascading Failure in Power Systems

    CERN Document Server

    Song, Jiajia; Ghanavati, Goodarz; Hines, Paul D H

    2014-01-01

    The modeling of cascading failure in power systems is difficult because of the many different mechanisms involved; no single model captures all of these mechanisms. Understanding the relative importance of these different mechanisms is an important step in choosing which mechanisms need to be modeled for particular types of cascading failure analysis. This work presents a dynamic simulation model of both power networks and protection systems, which can simulate a wider variety of cascading outage mechanisms, relative to existing quasi-steady state (QSS) models. The model allows one to test the impact of different load models and protections on cascading outage sizes. This paper describes each module of the developed dynamic model and demonstrates how different mechanisms interact. In order to test the model we simulated a batch of randomly selected $N-2$ contingencies for several different static load configurations, and found that the distribution of blackout sizes and event lengths from the proposed dynamic...

  13. On periodic orbits in discrete-time cascade systems

    Directory of Open Access Journals (Sweden)

    Huimin Li

    2006-01-01

    Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.

  14. The biogeography of trophic cascades on US oyster reefs.

    Science.gov (United States)

    Kimbro, David L; Byers, James E; Grabowski, Jonathan H; Hughes, A Randall; Piehler, Michael F

    2014-07-01

    Predators can indirectly benefit prey populations by suppressing mid-trophic level consumers, but often the strength and outcome of trophic cascades are uncertain. We manipulated oyster reef communities to test the generality of potential causal factors across a 1000-km region. Densities of oyster consumers were weakly influenced by predators at all sites. In contrast, consumer foraging behaviour in the presence of predators varied considerably, and these behavioural effects altered the trophic cascade across space. Variability in the behavioural cascade was linked to regional gradients in oyster recruitment to and sediment accumulation on reefs. Specifically, asynchronous gradients in these factors influenced whether the benefits of suppressed consumer foraging on oyster recruits exceeded costs of sediment accumulation resulting from decreased consumer activity. Thus, although predation on consumers remains consistent, predator influences on behaviour do not; rather, they interact with environmental gradients to cause biogeographic variability in the net strength of trophic cascades.

  15. Electron - positron cascades in multiple-laser optical traps

    CERN Document Server

    Vranic, Marija; Fonseca, Ricardo A; Silva, Luis O

    2016-01-01

    We present an analytical and numerical study of multiple-laser QED cascades induced with linearly polarised laser pulses. We analyse different polarisation orientations and propose a configuration that maximises the cascade multiplicity and favours the laser absorption. We generalise the analytical estimate for the cascade growth rate previously calculated in the field of two colliding linearly polarised laser pulses and account for multiple laser interaction. The estimate is verified by a comprehensive numerical study of four-laser QED cascades across a range of different laser intensities with QED PIC module of OSIRIS. We show that by using four linearly polarised 30 fs laser pulses, one can convert more than 50 % of the total energy to gamma-rays already at laser intensity $I\\simeq10^{24}\\ \\mathrm{W/cm^2}$. In this configuration, the laser conversion efficiency is higher compared with the case with two colliding lasers.

  16. On the polar cap cascade pair multiplicity of young pulsars

    CERN Document Server

    Timokhin, A N

    2015-01-01

    We study the efficiency of pair production in polar caps of young pulsars under a variety of conditions to estimate the maximum possible multiplicity of pair plasma in pulsar magnetospheres. We develop a semi-analytic model for calculation of cascade multiplicity which allows efficient exploration of the parameter space and corroborate it with direct numerical simulations. Pair creation processes are considered separately from particle acceleration in order to assess different factors affecting cascade efficiency, with acceleration of primary particles described by recent self-consistent non-stationary model of pair cascades. We argue that the most efficient cascades operate in the curvature radiation/synchrotron regime, the maximum multiplicity of pair plasma in pulsar magnetospheres is ~few x 10^5. The multiplicity of pair plasma in magnetospheres of young energetic pulsars weakly depends on the strength of the magnetic field and the radius of curvature of magnetic field lines and has a stronger dependence ...

  17. Aeroelasticity in Turbomachines. Comparison of Theoretical and Experimental Cascade Results.

    Science.gov (United States)

    1986-01-01

    time: T = t/T o To period of a cycle s t time s v velocity m/s Vre f reference velocity for reduced frequency m/s Vref Y for compresor cascade Vref...or quasi- three-dimensional cascades. Such interesting phenomena as rotor-stator interactions, stalled flutter and fully three-dimensional effects... stall , choke, shockwaves, coupling effects between the steady and unsteady flow fields...). The distribution of the blade surface pressure difference

  18. The CCFM Monte Carlo generator CASCADE 2.2.0

    CERN Document Server

    Jung, H; Deak, M; Grebenyuk, A; Hautmann, F; Hentschinski, M; Knutsson, A; Kraemer, M; Kutak, K; Lipatov, A; Zotov, N

    2010-01-01

    CASCADE is a full hadron level Monte Carlo event generator for ep, \\gamma p and p\\bar{p} and pp processes, which uses the CCFM evolution equation for the initial state cascade in a backward evolution approach supplemented with off - shell matrix elements for the hard scattering. A detailed program description is given, with emphasis on parameters the user wants to change and variables which completely specify the generated events.

  19. Synthesis of Pyridoacridines through Anionic Cascade Ring Closure

    DEFF Research Database (Denmark)

    Petersen, I.N.; Kristensen, Jesper Langgaard

    2014-01-01

    A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin. © Georg Thieme Verlag.......A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin. © Georg Thieme Verlag....

  20. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  1. Hydrothermal monitoring data from the Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, Steven E.; Gelwick, Katrina D.; Randolph-Flagg, Noah G.; Crankshaw, Ilana M.; Lundstrom, Elizabeth A.; McCulloch, Callum L.; Murveit, Anna M.; Newman, Alice C.; Mariner, Robert H.; Bergfeld, D.; Tucker, Dave S.; Schmidt, Mariek E.; Spicer, Kurt R.; Mosbrucker, Adam; Evans, William C.

    2013-01-01

    This database serves as a repository for hydrothermal-monitoring data collected at 25 sites in the U.S. portion of the Cascade Range volcanic arc. These data are intended to quantify baseline hydrothermal variability at most (10 of 12) of the highest-risk volcanoes in the Cascades, as defined by the U.S. Geological Survey’s (USGS’) National Volcanic Early Warning System (NVEWS) report (Ewert and others, 2005).

  2. Linewidth and tuning characteristics of terahertz quantum cascade lasers.

    Science.gov (United States)

    Barkan, A; Tittel, F K; Mittleman, D M; Dengler, R; Siegel, P H; Scalari, G; Ajili, L; Faist, J; Beere, H E; Linfield, E H; Davies, A G; Ritchie, D A

    2004-03-15

    We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 kHz. Characteristics are also reported for frequency tuning as the injection current is varied.

  3. The cascade of HIV care in Russia, 2011–2013

    OpenAIRE

    Anastasia Pokrovskaya; Anna Popova; Natalia Ladnaya; Oleg Yurin

    2014-01-01

    Introduction: The cascade of HIV care is one of the main tools to assess the individual and public health benefits of antiretroviral therapy (ART) and identify barriers of treatment as prevention (TasP) concept realization. We aimed to characterize the changes in engagement of HIV-positive persons in care in Russia during three years (2011–2013). Methods: We defined seven steps in the cascade of care framework: HIV infected (estimation data), HIV diagnosed, linked to HIV care, retained in HIV...

  4. Longitudinal gradients along a reservoir cascade

    Science.gov (United States)

    Miranda, L.E.; Habrat, M.D.; Miyazono, S.

    2008-01-01

    Reservoirs have traditionally been regarded as spatially independent entities rather than as longitudinal segments of a river system that are connected upstream and downstream to the river and other reservoirs. This view has frustrated advancement in reservoir science by impeding adequate organization of available information and by hindering interchanges with allied disciplines that often consider impounded rivers at the basin scale. We analyzed reservoir morphology, water quality, and fish assemblage data collected in 24 reservoirs of the Tennessee River; we wanted to describe longitudinal changes occurring at the scale of the entire reservoir series (i.e., cascade) and to test the hypothesis that fish communities and environmental factors display predictable gradients like those recognized for unimpounded rivers. We used a data set collected over a 7-year period; over 3 million fish representing 94 species were included in the data set. Characteristics such as reservoir mean depth, relative size of the limnetic zone, water retention time, oxygen stratification, thermal stratification, substrate size, and water level fluctuations increased in upstream reservoirs. Conversely, reservoir area, extent of riverine and littoral zones, access to floodplains and associated wetlands, habitat diversity, and nutrient and sediment inputs increased in downstream reservoirs. Upstream reservoirs included few, largely lacustrine, ubiquitous fish taxa that were characteristic of the lentic upper reaches of the basin. Fish species richness increased in a downstream direction from 12 to 67 species/ reservoir as riverine species became more common. Considering impoundments at a basin scale by viewing them as sections in a river or links in a chain may generate insight that is not always available when the impoundments are viewed as isolated entities. Basin-scale variables are rarely controllable but constrain the expression of processes at smaller scales and can facilitate the

  5. Cascadable excitability in optically injected microdisks

    Science.gov (United States)

    Van Vaerenbergh, Thomas; Alexander, Koen; Fiers, Martin; Mechet, Pauline; Dambre, Joni; Bienstman, Peter

    2014-05-01

    All-optical spiking neural networks would allow high speed parallelized processing of time-encoded information, using the same energy efficient computational principles as our brain. As the neurons in these networks need to be able to process pulse trains, they should be excitable. Using simulations, we demonstrate Class 1 excitability in optically injected microdisk lasers, and propose a cascadable optical spiking neuron design. The neuron has a clear threshold and an integrating behavior. In addition, we show that the optical phase of the input pulses can be used to create inhibitory, as well as excitatory perturbations. Furthermore, we incorporate our optical neuron design in a topology that allows a disk to react on excitations from other disks. Phase tuning of the intermediate connections allows to control the disk response. Additionally, we investigate the sensitivity of the disk circuit to deviations in driving current and locking signal wavelength detuning. Using state-of-the-art fabrication techniques for microdisk laser, the standard deviation of the lasing wavelength is still about one order of magnitude too large. Finally, as the dynamical behavior of the microdisks is identical to the behavior in Semiconductor Ring Lasers (SRL), we compare the excitability mechanism due to optically injection with the previously proposed excitability due to asymmetry in the intermodal coupling in SRLs, as the latter mechanism can also be induced in disks due to, e.g., asymmetry in the external reaction. In both cases, the symmetry between the two counter-propagating modes of the cavity needs to be broken to prevent switching to the other mode, and allow the system to relax to its initial state after a perturbation. However, the asymmetry due to optical injection results in an integrating spiking neuron, whereas the asymmetry in the intermodal coupling is known to result in a resonating spiking neuron.

  6. Low power-consumption quantum cascade lasers

    Science.gov (United States)

    Katsuyama, Tsukuru; Hashimoto, Jun-ichi; Yoshinaga, Hiroyuki; Mori, Hiroki; Tsuji, Yukihiro; Murata, Makoto; Ekawa, Mitsuru; Tanahashi, Toshiyuki

    2015-01-01

    Quantum cascade lasers (QCLs) are promising light sources for real time high-sensitivity gas sensing in the mid-infrared region. For the practical use of QCLs as a compact and portable gas sensor, their power-consumption needs to be reduced. We report a successful operation of a low power-consumption distributed feedback (DFB) QCL. For the reduction of power consumption, we introduced a vertical-transition structure in a core region to improve carrier transition efficiency and reduced the core volume. DFB-QCL epitaxial structure was grown by low-pressure OMVPE. The core region consists of AlInAs/GaInAs superlattices lattice-matched to InP. A first-order Bragg-grating was formed near the core region to obtain a large coupling coefficiency. A mesa-strip was formed by reactive ion etching and a buried-heterostructure was fabricated by the regrowth of semi-insulating InP. High-reflective facet coatings were also performed to decrease the mirror loss for the reduction of the threshold current. A device (5x500μm) operated with a single mode in the wavelength region from 7.23μm to 7.27μm. The threshold current and threshold voltage under CW operation at 20 °C were 52mA and 8.4V respectively. A very low threshold power-consumption as low as 0.44 W was achieved, which is among the lowest values at room temperature to our knowledge.

  7. Modal character of atmospheric black carbon size distributions

    Science.gov (United States)

    Berner, A.; Sidla, S.; Galambos, Z.; Kruisz, C.; Hitzenberger, R.; ten Brink, H. M.; Kos, G. P. A.

    1996-08-01

    Samples of atmospheric aerosols, collected with cascade impactors in the urban area of Vienna (Austria) and at a coastal site on the North Sea, were investigated for black carbon (BC) as the main component of absorbing material and for mass. The size distributions are structured. The BC distributions of these samples show a predominant mode, the accumulation aerosol, in the upper submicron size range, a less distinct finer mode attributable to fresh emissions from combustion sources, and a distinct coarse mode of unclear origin. It is important to note that some parameters of the accumulation aerosol are related statistically, indicating the evolution of the atmospheric accumulation aerosol.

  8. Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Taubman, Matthew S.

    2013-06-04

    Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

  9. Forest Vegetation Monitoring Protocol for National Parks in the North Coast and Cascades Network

    Science.gov (United States)

    Woodward, Andrea; Hutten, Karen M.; Boetsch, John R.; Acker, Steven A.; Rochefort, Regina M.; Bivin, Mignonne M.; Kurth, Laurie L.

    2009-01-01

    Plant communities are the foundation for terrestrial trophic webs and animal habitat, and their structure and species composition are an integrated result of biological and physical drivers (Gates, 1993). Additionally, they have a major role in geologic, geomorphologic and soil development processes (Jenny, 1941; Stevens and Walker, 1970). Throughout most of the Pacific Northwest, environmental conditions support coniferous forests as the dominant vegetation type. In the face of anthropogenic climate change, forests have a global role as potential sinks for atmospheric carbon (Goodale and others, 2002). Consequently, knowledge of the status of forests in the three large parks of the NCCN [that is, Mount Rainier (MORA), North Cascades (NOCA), and Olympic (OLYM) National Parks] is fundamental to understanding the condition of Pacific Northwest ecosystems. Diverse climate and soil properties across the Pacific Northwest result in a variety of forest types (Franklin and Dyrness, 1973; Franklin and others, 1988; Henderson and others, 1989, 1992). The mountainous terrain of Mount Rainier, North Cascades, and Olympic National Parks create steep elevational and precipitation gradients within and among the parks: collectively, these parks span from sea level to more than 4,200 m; and include areas with precipitation from 90 to more than 500 cm. The resulting forests range from coastal rainforests with dense understories and massive trees draped with epiphytes; to areas with drought-adapted Ponderosa pines; to high-elevation subalpine fir forests interspersed with meadows just below treeline (table 1). These forests, in turn, are the foundation for other biotic communities constituting Pacific Northwest ecosystems.

  10. Atmosphere: Power, Critique, Politics

    DEFF Research Database (Denmark)

    Albertsen, Niels

    2016-01-01

    This paper hans three interrelated parts. First, atmosphere is approached through the concept of power. Atmospheres 'grip' us directly or mediate power indirectly by manipulating moods and evoking emotions. How does atmosphere relate to different conceptions of power? Second, atmospheric powers m...... be critiqued. Which conception of critique can be involved? Third, critiquing atmospheric powers can generate political conflict. How does atmospheric disputes relate to conceptions of politics and the political?...

  11. Cascaded systems analysis of photon counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Zbijewski, W.; Gang, G.; Stayman, J. W. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Taguchi, K.; Carrino, J. A. [Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Lundqvist, M.; Fredenberg, E. [Philips Healthcare, Solna 171 41 (Sweden); Siewerdsen, J. H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    2014-10-15

    Purpose: Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Methods: A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1–7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. Results: The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f{sub 50} (spatial

  12. Terahertz inverse synthetic aperture radar (ISAR) imaging with a quantum cascade laser transmitter.

    Science.gov (United States)

    Danylov, Andriy A; Goyette, Thomas M; Waldman, Jerry; Coulombe, Michael J; Gatesman, Andrew J; Giles, Robert H; Qian, Xifeng; Chandrayan, Neelima; Vangala, Shivashankar; Termkoa, Krongtip; Goodhue, William D; Nixon, William E

    2010-07-19

    A coherent transceiver using a THz quantum cascade (TQCL) laser as the transmitter and an optically pumped molecular laser as the local oscillator has been used, with a pair of Schottky diode mixers in the receiver and reference channels, to acquire high-resolution images of fully illuminated targets, including scale models and concealed objects. Phase stability of the received signal, sufficient to allow coherent image processing of the rotating target (in azimuth and elevation), was obtained by frequency-locking the TQCL to the free-running, highly stable optically pumped molecular laser. While the range to the target was limited by the available TQCL power (several hundred microwatts) and reasonably strong indoor atmospheric attenuation at 2.408 THz, the coherence length of the TQCL transmitter will allow coherent imaging over distances up to several hundred meters. Image data obtained with the system is presented.

  13. Measuring the Turbulent Cascade in the Solar Wind

    Science.gov (United States)

    MacBride, B. T.; Forman, M. A.; Smith, C. W.

    2006-12-01

    Kolmogorov's famous 4/5 law for the Navier-Stokes equation states that in isotropic hydrodynamic (HD) turbulence, the third moment of longitudinal velocity fluctuations at a spatial distance L is (4/5) ɛ ěrt L ěrt where ɛ is the turbulent energy cascade rate = heating rate per unit mass. A definite, signed, third moment is a fundamental property of the turbulent velocity fluctuations arising from the non-linear term in the Navier-Stokes equation, the only direct indicator that a cascade exists, the only measure of what direction that cascade takes (to smaller or larger spatial scales), and the truest indication of the cascade rate. The solar wind is MHD, however, and its turbulence is anisotropic. Dasso et al. (2005) perform a study on the anisotropy in the solar wind as a function of flow speed and find that there exists "quasi-two-dimensional" turbulence in low speed streams and a one dimensional "slab" structure in high speed flow. Politano and Pouquet (1998; PP) have derived an exact expression, valid in anisotropic situations, for the divergence with lag vector L of a certain vector third moment of the fluctuations in the Elsasser variables as a function of L. We perform an analysis of the third-order moment derived by PP. We use 8 years of ACE combine 64-s magnetic field and plasma measurements in variably defined subsets to compute the Elsasser variables in mean-field coordinates for different solar wind conditions (high/low wind speed, yearly, etc.). Most significantly, we attempt to separately resolve parallel and perpendicular cascades relative to the mean magnetic field. We find (1) the third moment structure functions are approximately proportional to lag as expected, (2) the inferred energy dissipation rate for outward-moving waves is larger than for inward-moving waves with many intervals showing evidence of an inverse cascade of the minority component, (3) the total energy-dissipation rate inferred by this method is frequently in disagreement

  14. Neutrino induced charged-current coherent $\\rho$ production

    CERN Document Server

    ,

    2013-01-01

    We present the latest results of coherent $\\rho$ (Coh$\\rho$) production using the large data set collected by the NOMAD detector in which the momenta, charges, and photons are precisely measured. We discuss the application of using Coh$\\rho$ process to constrain the neutrino flux with the proposed Long-Baseline Neutrino Experiment Near Detector, the high resolution Straw Tube Tracker.

  15. Neutrino induced showers from gamma-ray bursts

    NARCIS (Netherlands)

    Presani, E.

    2011-01-01

    Neutrino’s (ongeladen, elementaire deeltjes) komen voor in drie gedaantes. Elk van dit soort neutrino’s interageert op zijn eigen manier op de materie. Bij de interactie kan een geladen zwak boson worden uitgewisseld. De neutrino’s veranderen daarbij in hun geladen partner (muon-neutrino naar muon,

  16. Neutrino-induced upward stopping muons in Super-Kamiokande

    CERN Document Server

    Fukuda, Y; Itow, Y; Kajita, T; Kameda, J; Kasuga, S; Kobayashi, K; Kobayashi, Y; Koshio, Y; Miura, M; Nakahata, M; Nakayama, S; Obayashi, Y; Okada, A; Okumura, K; Sakurai, N; Shiozawa, M; Suzuki, Y; Takeuchi, H; Takeuchi, Y; Totsuka, Y; Yamada, S; Earl, M; Habig, A; Kearns, E; Messier, M D; Scholberg, K; Stone, J L; Sulak, L R; Walter, C W; Goldhaber, M; Barszczak, T; Casper, D; Gajewski, W; Kropp, W R; Mine, S; Price, L R; Smy, M B; Sobel, H W; Vagins, M R; Ganezer, K S; Keig, W E; Ellsworth, R W; Tasaka, S; Kibayashi, A; Learned, J G; Matsuno, S; Stenger, V J; Takemori, D; Ishii, T; Ishino, H; Kobayashi, T; Nakamura, K; Oyama, Y; Sakai, A; Sakuda, M; Sasaki, O; Echigo, S; Kohama, M; Suzuki, A T; Inagaki, T; Nishikawa, K; Haines, T J; Blaufuss, E; Kim, B K; Sanford, R; Svoboda, R; Chen, M L; Goodman, J A; Sullivan, G W; Hill, J; Jung, C K; Martens, K; Mauger, C; McGrew, C; Sharkey, E; Viren, B; Yanagisawa, C; Doki, W; Kirisawa, M; Inaba, S; Miyano, K; Okazawa, H; Saji, C; Takahashi, M; Takahata, M; Higuchi, K; Nagashima, Y; Takita, M; Yamaguchi, T; Yoshida, M; Kim, S B; Etoh, M; Hasegawa, A; Hasegawa, T; Hatakeyama, S; Inoue, K; Iwamoto, T; Koga, M; Maruyama, T; Ogawa, H; Shirai, J; Suzuki, A; Tsushima, F; Koshiba, M; Hatakeyama, Y; Koike, M; Nemoto, M; Nishijima, K; Fujiyasu, H; Futagami, T; Hayato, Y; Kanaya, Y; Kaneyuki, K; Watanabe, Y; Kielczewska, D; George, J S; Stachyra, A L; Wilkes, R J; Young, K K

    1999-01-01

    A total of 137 upward stopping muons of minimum energy 1.6 GeV are observed by Super-Kamiokande during 516 detector live days. The measured muon flux is 0.39+/-0.04(stat.)+/-0.02(syst.)x10^{-13}cm^{-2}s^{-1}sr^{-1} compared to an expected flux of 0.73+/-0.16(theo.)x10^{-13}cm^{-2}s^{-1}sr^{-1}. Using our previously-published measurement of the upward through-going muon flux, we calculate the stopping/through-going flux ratio R}, which has less theoretical uncertainty. The measured value of R=0.22+/-0.02(stat.)+/-0.01(syst.) is significantly smaller than the value 0.37^{+0.05}_{-0.04}(theo.) expected using the best theoretical information (the probability that the measured R is a statistical fluctuation below the expected value is 0.39%). A simultaneous fitting to zenith angle distributions of upward stopping and through-going muons gives a result which is consistent with the hypothesis of neutrino oscillations with the parameters sin^2 2\\theta >0.7 and 1.5x10^{-3} < \\Delta m^2 < 1.5x10^{-2} eV^2 at 90% ...

  17. Reconstruction of neutrino-induced showers with ANTARES

    NARCIS (Netherlands)

    Dorosti Hasankiadeh, Qader

    2013-01-01

    Op aarde zijn kosmische deeltjes gemeten met extreem hoge energieën. De bijbehorende bronnen we kennen niet, we weten zelfs niet of die misschien binnen ons melkwegstelsel liggen. Wel weten we dat in uitbarstingen van kosmische energie ook neutrino's worden geproduceerd. Boven alle andere deeltjes h

  18. Neutrino induced coherent single pion production at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Nahnhauer, R. (Institut fuer Hochenergiephysik, Zeuthen (Germany, F.R.))

    1991-04-01

    Available data about coherent single pion production in charged and neutral current reactions are reviewed and compared to the results of two corresponding models. A comparison of the axialvector-isovector coupling constant /{beta}/ derived in different experiments is given. Agreement is found between them and the prediction of the Standard Model. Possible new information from future analyses is mentioned. (orig.).

  19. Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependence

    Science.gov (United States)

    Korkali, Mert; Veneman, Jason G.; Tivnan, Brian F.; Bagrow, James P.; Hines, Paul D. H.

    2017-03-01

    Increased interconnection between critical infrastructure networks, such as electric power and communications systems, has important implications for infrastructure reliability and security. Others have shown that increased coupling between networks that are vulnerable to internetwork cascading failures can increase vulnerability. However, the mechanisms of cascading in these models differ from those in real systems and such models disregard new functions enabled by coupling, such as intelligent control during a cascade. This paper compares the robustness of simple topological network models to models that more accurately reflect the dynamics of cascading in a particular case of coupled infrastructures. First, we compare a topological contagion model to a power grid model. Second, we compare a percolation model of internetwork cascading to three models of interdependent power-communication systems. In both comparisons, the more detailed models suggest substantially different conclusions, relative to the simpler topological models. In all but the most extreme case, our model of a “smart” power network coupled to a communication system suggests that increased power-communication coupling decreases vulnerability, in contrast to the percolation model. Together, these results suggest that robustness can be enhanced by interconnecting networks with complementary capabilities if modes of internetwork failure propagation are constrained.

  20. TOPOLOGY AND CASCADING LINE OUTAGES IN POWER GRIDS

    Institute of Scientific and Technical Information of China (English)

    David L. PEPYNE

    2007-01-01

    Motivated by the small world network research of Watts & Strogatz, this paper studies relationships between topology and cascading line outages in electric power grids. Cascading line outages are a type of cascading collapse that can occur in power grids when the transmission network is congested. It is characterized by a self-sustaining sequence of line outages followed by grid breakup, which generally leads to widespread blackout. The main findings of this work are twofold: On one hand, the work suggests that topologies with more disorder in their interconnection topology tend to be robust with respect to cascading line outages in the sense of being able to support greater generation and demand levels than more regularly interconnected topologies. On the other hand, the work suggests that topologies with more disorder tend to be more fragile in that should a cascade get started, they tend to break apart after fewer outages than more regularly interconnected topologies. Thus, as has been observed in other complex networks, there appears to be a tradeoff between robustness and fragility.These results were established using synthetically generated power grid topologies and verified using the IEEE 57 bus and 188 bus power grid test cases.

  1. Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependence

    Science.gov (United States)

    Korkali, Mert; Veneman, Jason G.; Tivnan, Brian F.; Bagrow, James P.; Hines, Paul D. H.

    2017-01-01

    Increased interconnection between critical infrastructure networks, such as electric power and communications systems, has important implications for infrastructure reliability and security. Others have shown that increased coupling between networks that are vulnerable to internetwork cascading failures can increase vulnerability. However, the mechanisms of cascading in these models differ from those in real systems and such models disregard new functions enabled by coupling, such as intelligent control during a cascade. This paper compares the robustness of simple topological network models to models that more accurately reflect the dynamics of cascading in a particular case of coupled infrastructures. First, we compare a topological contagion model to a power grid model. Second, we compare a percolation model of internetwork cascading to three models of interdependent power-communication systems. In both comparisons, the more detailed models suggest substantially different conclusions, relative to the simpler topological models. In all but the most extreme case, our model of a “smart” power network coupled to a communication system suggests that increased power-communication coupling decreases vulnerability, in contrast to the percolation model. Together, these results suggest that robustness can be enhanced by interconnecting networks with complementary capabilities if modes of internetwork failure propagation are constrained. PMID:28317835

  2. Up and down cascades: three-dimensional magnetic field model.

    Science.gov (United States)

    Blanter, E M; Shnirman, M G; Le Mouël, J L

    2002-06-01

    In our previous works we already have proposed a two-dimensional model of geodynamo. Now we use the same approach to build a three-dimensional self-excited geodynamo model that generates a large scale magnetic field from whatever small initial field, using the up and down cascade effects of a multiscale turbulent system of cyclones. The multiscale system of turbulent cyclones evolves in six domains of an equatorial cylindrical layer of the core. The appearance of new cyclones is realized by two cascades: a turbulent direct cascade and an inverse cascade of coupling of similar cyclones. The interaction between the different domains is effected through a direct cascade parameter which is essential for the statistics of the long-life symmetry breaking. Generation of the secondary magnetic field results from the interaction of the components of the primary magnetic field with the turbulent cyclones. The amplification of the magnetic field is due to the transfer of energy from the turbulent helical motion to the generated magnetic field. The model demonstrates a phase transition through the parameter characterizing this energy transfer. In the supercritical domain we obtain long-term intervals of constant polarity (chrons) and quick reversals; relevant time constants agree with paleomagnetic observations. Possible application of the model to the study of the geometrical structure of the geomagnetic field (and briefly other planetary fields) is discussed.

  3. Critical assessment and ramifications of a purported marine trophic cascade

    Science.gov (United States)

    Grubbs, R. Dean; Carlson, John K; Romine, Jason G.; Curtis, Tobey H; McElroy, W. David; McCandless, Camilla T; Cotton, Charles F; Musick, John A.

    2016-01-01

    When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the “Save the Bay, Eat a Ray” fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.

  4. A Cascading Model Of An Active Magnetic Regenerator System

    DEFF Research Database (Denmark)

    Tahavori, M.; Filonenko, K.; Veje, C. T.;

    2016-01-01

    In recent years, significant amounts of studies have been done on modeling and analysis of active magnetic regenerators (AMRs). Depending on the AMR geometry and the magnetocaloric material being modeled, the AMR may not be able to provide the required performance demanded by practical applications....... Some AMR models in the literature predict high performance but with relatively low temperature spans at either end of the AMR. Therefore, they may not be sufficient for practical applications, such as providing the heat exchanger temperature spans required for residential and commercial space air...... conditioning. To remedy this, one solution is cascading of multiple single layer AMRs. In this work, a cascading AMR model is presented and studied. In a cascade configuration, N number of single layer AMRs are connected. The results show that higher hot and cold side temperature differences may be achieved...

  5. Robustness and perturbation in the modeled cascade heart rate variability

    Science.gov (United States)

    Lin, D. C.

    2003-03-01

    In this study, numerical experiments are conducted to examine the robustness of using cascade to describe the multifractal heart rate variability (HRV) by perturbing the hierarchical time scale structure and the multiplicative rule of the cascade. It is shown that a rigid structure of the multiple time scales is not essential for the multifractal scaling in healthy HRV. So long as there exists a tree structure for the multiplication to take place, a multifractal HRV and related properties can be captured by using the cascade. But the perturbation of the multiplicative rule can lead to a qualitative change. In particular, a multifractal to monofractal HRV transition can result after the product law is perturbed to an additive one at the fast time scale. We suggest that this explains the similar HRV scaling transition in the parasympathetic nervous system blockade.

  6. Robustness of Power-law Behavior in Cascading Failure Models

    CERN Document Server

    Sloothaak, F; Zwart, A P

    2016-01-01

    Inspired by reliability issues in electric transmission networks, we use a probabilistic approach to study the occurrence of large failures in a stylized cascading failure model. In this model, lines have random capacities that initially meet the load demands imposed on the network. Every single line failure changes the load distribution in the surviving network, possibly causing further lines to become overloaded and trip as well. An initial single line failure can therefore potentially trigger massive cascading effects, and in this paper we measure the risk of such cascading events by the probability that the number of failed lines exceeds a certain large threshold. Under particular critical conditions, the exceedance probability follows a power-law distribution, implying a significant risk of severe failures. We examine the robustness of the power-law behavior by exploring under which assumptions this behavior prevails.

  7. Irreversibility of the two-dimensional enstrophy cascade

    CERN Document Server

    Piretto,; Boffetta, G

    2016-01-01

    We study the time irreversibility of the direct cascade in two-dimensional turbulence by looking at the time derivative of the square vorticity along Lagrangian trajectories, a quantity which we call metenstrophy. By means of extensive numerical simulations we measure the time irreversibility from the asymmetry of the PDF of the metenstrophy and we find that it increases with the Reynolds number of the cascade, similarly to what found in three-dimensional turbulence. A detailed analysis of the different contributions to the enstrophy budget reveals a remarkable difference with respect to what observed for the direct cascade, in particular the role of the statistics of the forcing to determine the degree of irreversibility.

  8. Improving performance using cascade control and a Smith predictor.

    Science.gov (United States)

    Kaya, I

    2001-01-01

    Many investigations have been done on tuning proportional-integral-derivative (PID) controllers in single-input single-output (SISO) systems. However, only a few investigations have been carried out on tuning PID controllers in cascade control systems. In this paper, a new approach, namely the use of a Smith predictor in the outer loop of a cascade control system, is investigated. The method can be used in temperature control problems where the secondary part of the process (the inner loop) may have a negligible delay while the primary loop (the outer loop) has a time-delay. Two different approaches, including an autotuning method, to find the controller parameters are proposed. It is shown by some examples that the proposed structure as expected can provide better performance than conventional cascade control, a Smith predictor scheme or single feedback control system.

  9. Quasi-isotropic cascade in MHD turbulence with mean field

    CERN Document Server

    Grappin, Roland; Gürcan, Özgür

    2012-01-01

    We propose a phenomenological theory of incompressible magnetohydrodynamic turbulence in the presence of a strong large-scale magnetic field, which establishes a link between the known anisotropic models of strong and weak MHD turbulence We argue that the Iroshnikov-Kraichnan isotropic cascade develops naturally within the plane perpendicular to the mean field, while oblique-parallel cascades with weaker amplitudes can develop, triggered by the perpendicular cascade, with a reduced flux resulting from a quasi-resonance condition. The resulting energy spectrum $E(k_\\parallel,k_\\bot)$ has the same slope in all directions. The ratio between the extents of the inertial range in the parallel and perpendicular directions is equal to $b_{rms}/B_0$. These properties match those found in recent 3D MHD simulations with isotropic forcing reported in [R. Grappin and W.-C. M\\"uller, Phys. Rev. E \\textbf{82}, 26406 (2010)].

  10. Performance validation of a cascade control system through

    Directory of Open Access Journals (Sweden)

    A. Lakshmi Sangeetha

    2016-11-01

    Full Text Available The work analyzes the performance characteristics of a cascade control system when interconnected with various network architectures, such as Internet, mobile and wireless networks. The cascade control system consists of level and flow as primary and secondary variables, respectively. The web-enabled monitoring and control are realized using three techniques namely remote client–server, ActiveX-data socket and web publishing tool. Mobile network is established by interfacing the control system with a GSM modem which enables the monitoring of process parameters through mobile phones. The cascade control system is also monitored wirelessly from remote locations with advent of an indigenous wireless sensor node. The performance analysis proved that wireless monitoring may be considered as an effective alternate technique to the Internet-based communication especially for shorter distances.

  11. Cascaded Parametric Amplification for Highly Efficient Terahertz Generation

    CERN Document Server

    Ravi, Koustuban; Cirmi, Giovanni; Reichert, Fabian; Schimpf, Damian N; Muecke, Oliver D; Kaertner, Franz X

    2016-01-01

    A highly efficient, practical approach to high-energy terahertz (THz) generation based on spectrally cascaded optical parametric amplification (THz-COPA) is introduced. The THz wave initially generated by difference frequency generation between a strong narrowband optical pump and optical seed (0.1-10% of pump energy) kick-starts a repeated or cascaded energy down-conversion of pump photons. This helps to greatly surpass the quantum-defect efficiency and results in exponential growth of THz energy over crystal length. In cryogenically cooled periodically poled lithium niobate, energy conversion efficiencies >8% for 100 ps pulses are predicted. The calculations account for cascading effects, absorption, dispersion and laser-induced damage. Due to the coupled nonlinear interaction of multiple triplets of waves, THz-COPA exhibits physics distinct from conventional three-wave mixing parametric amplifiers. This in turn governs optimal phase-matching conditions, evolution of optical spectra as well as limitations o...

  12. Cascaded passive silicon microrings for large bandwidth slow light device

    Energy Technology Data Exchange (ETDEWEB)

    Li Yuntao; Hu Yingtao; Xiao Xi; Li Zhiyong; Yu Yude; Yu Jinzhong, E-mail: ytli@semi.ac.cn [State Key Laboratory of integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China)

    2011-02-01

    Slow light devices have important applications in the areas of data buffering, signal processing, and phased array antenna. Cascaded microring resonators structure can obtain large delay and also enhance the bandwidth, which was considered as a potential approach for future on-chip optical buffer. In this paper, we demonstrated a large bandwidth slow light device using cascaded Silicon-on-insulator (SOI) based microring resonators. With carefully designed the gap between the bus and the ring waveguides and the distances between the adjacent rings, a 57 ps group delay was observed and 83 Gbps maximum allowable bit rate is suggested according the measured 3 dB spectral bandwidth in the 8-stage cascaded microrings.

  13. Highly Loaded Fan by Using Tandem Cascade Rotor Blade

    Science.gov (United States)

    Hasegawa, Hiroaki; Suga, Shinya; Matsuoka, Akinori

    For axial flow compressors and fans in the aircraft engines higher pressure ratio is required in order to attain the high thrust engines. In this study, the fan with the tandem cascades was introduced to increase the fan pressure ratio. The use of tandem cascades in the fan allows savings in length and weight and therefore a compact fan could be built. The design of fan with tandem cascades and the fan testing were carried out to develop the high pressure ratio fan for the Air Turbo Ramjet (ATR) propulsion system. The ATR is a combined cycle engine which performs like a turbojet engine at subsonic speeds and a ramjet at supersonic speeds. In particular, high fan pressure ratio contributes to increase the engine thrust during subsonic flight at which the engine does not make use of ram effect. The results of the fan testing indicate that the pressure ratio of 2.2 is achieved in single stage fan.

  14. Cascaded VLSI Chips Help Neural Network To Learn

    Science.gov (United States)

    Duong, Tuan A.; Daud, Taher; Thakoor, Anilkumar P.

    1993-01-01

    Cascading provides 12-bit resolution needed for learning. Using conventional silicon chip fabrication technology of VLSI, fully connected architecture consisting of 32 wide-range, variable gain, sigmoidal neurons along one diagonal and 7-bit resolution, electrically programmable, synaptic 32 x 31 weight matrix implemented on neuron-synapse chip. To increase weight nominally from 7 to 13 bits, synapses on chip individually cascaded with respective synapses on another 32 x 32 matrix chip with 7-bit resolution synapses only (without neurons). Cascade correlation algorithm varies number of layers effectively connected into network; adds hidden layers one at a time during learning process in such way as to optimize overall number of neurons and complexity and configuration of network.

  15. Cascading failure analysis and restoration strategy in an interdependent network

    Science.gov (United States)

    Hong, Sheng; Lv, Chuan; Zhao, Tingdi; Wang, Baoqing; Wang, Jianghui; Zhu, Juxing

    2016-05-01

    In modern society, many infrastructures are interdependent owing to functional and logical relations among components in different systems. These networked infrastructures can be modeled as interdependent networks. In the real world, different networks carry different traffic loads whose values are dynamic and stem from the load redistribution in the same network and disturbance from the interdependent network. Interdependency makes interdependent networks so fragile that even a slight initial disturbance may lead to a cascading failure of the entire systems. In this paper, interdependencies among networks are modeled and a failure cascade process is studied considering their effects on failure propagation. Meanwhile, an in-process restoration strategy after the initial failure is investigated. The restoration effects depend strongly on the trigger timing, restoration probability and priority of the restoration actions along with the additional disturbances. Our findings highlight the necessity to decrease the large-scale cascading failure by structuring and managing an interdependent network reasonably.

  16. Bearing-Only Formation Control for Cascade Multirobots

    Directory of Open Access Journals (Sweden)

    Qing Han

    2016-01-01

    Full Text Available A new formation control method is proposed, which is used to queue multirobots in a single-direction cascade structure. In the cascade formation, each robot is a follower for the previous robot and a leader for the next robot, and the robots in the middle act as both leader and follower. The follower robot can only observe the bearing information of the leader robot. The observability of the cascade leader-follower formation is studied, which shows that the bearing-only observation meets the observability conditions required for the nonlinear system. Based on the bearing-only observations, the unscented Kalman filter (UKF is employed for the state estimation of the leader and the follower robots at all levels, which enables the real-time movement control of the follower robots via the input-output feedback control. Simulation results demonstrate that the proposed approach can efficiently control the formation of multirobots as desired.

  17. Cascaded effects of spatial adaptation in the early visual system.

    Science.gov (United States)

    Dhruv, Neel T; Carandini, Matteo

    2014-02-05

    Virtually all stages of the visual system exhibit adaptation: neurons adjust their responses based on the recent stimulus history. While some of these adjustments occur at specific stages, others may be inherited from earlier stages. How do adaptation effects cascade along the visual system? We measured spatially selective adaptation at two successive stages in the mouse visual system: visual thalamus (LGN) and primary visual cortex (V1). This form of adaptation affected both stages but in drastically different ways: in LGN it only changed response gain, while in V1 it also shifted spatial tuning away from the adaptor. These effects, however, are reconciled by a simple model whereby V1 neurons summate LGN inputs with a fixed, unadaptable weighting profile. These results indicate that adaptation effects cascade through the visual system, that this cascading can shape selectivity, and that the rules of integration from one stage to the next are not themselves adaptable.

  18. Measurement of the atmospheric nu (mu) energy spectrum from 100 GeV to 200 TeV with the ANTARES telescope

    NARCIS (Netherlands)

    Adrian-Martinez, S.; Albert, A.; Al Samarai, I.; Andre, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Astraatmadja, T.; Aubert, J. -J.; Baret, B.; Barrios-Marti, J.; Basa, S.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bogazzi, C.; Bouhou, B.; Bouwhuis, M.C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carloganu, C.; Carr, J.; Cecchini, S.; Charif, Z.; Charvis, Ph.; Chiarusi, T.; Circella, M.; Classen, F.; Core, L.; Costantini, H.; Coyle, P.; Creusot, A.; Curtil, C.; Dekeyser, I.; Deschamps, A.; De Bonis, G.; Decowski, M. P.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Dumas, A.; Eberl, T.; Emanuele, U.; Enzenhoefer, A.; Ernenwein, J. -P.; Escoffier, S.; Fehn, K.; Fermani, P.; Flaminio, V.; Folger, F.; Fritsch, U.; Fusco, L. A.; Galata, S.; Gay, P.; Geisselsoeder, S.; Geyer, K.; Giacomelli, G.; Giordano, V.; Gleixner, A.; Gomez-Gonzalez, J. P.; Graf, K.; Guillard, G.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernandez-Rey, J. J.; Herold, B.; Hoessl, J.; James, C. W.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kooijman, P.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lambard, E.; Lambard, G.; Larosa, G.; Lattuada, D.; Lefevre, D.; Leonora, E.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J. A.; Martini, S.; Michael, T.; Montaruli, T.; Morganti, M.; Motz, H.; Mueller, C.; Neff, M.; Nezri, E.; Palioselitis, D.; Pavalas, G. E.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Richter, R.; Riviere, C.; Robert, A.; Roensch, K.; Rostovtsev, A.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schmid, J.; Schnabel, J.; Schulte, S.; Schuessler, F.; Seitz, T.; Shanidze, R.; Sieger, C.; Simeone, F.; Spies, A.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Sanchez-Losa, A.; Taiuti, M.; Tamburini, C.; Tayalati, Y.; Trovato, A.; Vallage, B.; Vallee, C.; Van Elewyck, V.; Vernin, P.; Visser, E.; Wagner, S.; Wilms, J.; de Wolf, E.; Yatkin, K.; Yepes, H.; Zornoza, J. D.; Zuniga, J.

    2013-01-01

    Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In this paper, a measurement of the atmospheric energy spectrum in the energy range 0.1-200 TeV is presented, using data collected by the ANTARES underwater neutrino telescope from

  19. MATCASC: A tool to analyse cascading line outages in power grids

    CERN Document Server

    Koç, Yakup; Araujo, Nuno A M; Warnier, Martijn

    2013-01-01

    Blackouts in power grids typically result from cascading failures. The key importance of the electric power grid to society encourages further research into sustaining power system reliability and developing new methods to manage the risks of cascading blackouts. Adequate software tools are required to better analyze, understand, and assess the consequences of the cascading failures. This paper presents MATCASC, an open source MATLAB based tool to analyse cascading failures in power grids. Cascading effects due to line overload outages are considered. The applicability of the MATCASC tool is demonstrated by assessing the robustness of IEEE test systems and real-world power grids with respect to cascading failures.

  20. One-dimensional hydrodynamic model generating a turbulent cascade

    Science.gov (United States)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  1. Feigenbaum Cascade of Discrete Breathers in a Model of DNA

    CERN Document Server

    Maniadis, P; Bishop, A R; Rasmussen, K \\O

    2010-01-01

    We demonstrate that period-doubled discrete breathers appear from the anti-continuum limit of the driven Peyrard-Bishop-Dauxois model of DNA. These novel breathers result from a stability overlap between sub-harmonic solutions of the driven Morse oscillator. Sub-harmonic breathers exist whenever a stability overlap is present within the Feigenbaum cascade to chaos and therefore an entire cascade of such breathers exists. This phenomenon is present in any driven lattice where the on-site potential admits sub-harmonic solutions. In DNA these breathers may have ramifications for cellular gene expression.

  2. Cascade Control of Magnetic Levitation with Sliding Modes

    Directory of Open Access Journals (Sweden)

    Eroğlu Yakup

    2016-01-01

    Full Text Available The effectiveness and applicability of magnetic levitation systems need precise feedback control designs. A cascade control approach consisting of sliding mode control plus sliding mode control (SMC plus SMC is designed to solve position control problem and to provide a high control performance and robustness to the magnetic levitation plant. It is shown that the SMC plus SMC cascade controller is able to eliminate the effects of the inductance related uncertainties of the electromagnetic coil of the plant and achieve a robust and precise position control. Experimental and numerical results are provided to validate the effectiveness and feasibility of the method.

  3. Maximizing the Spread of Cascades Using Network Design

    CERN Document Server

    Sheldon, Daniel; Elmachtoub, Adam N; Finseth, Ryan; Sabharwal, Ashish; Conrad, Jon; Gomes, Carla P; Shmoys, David; Allen, William; Amundsen, Ole; Vaughan, William

    2012-01-01

    We introduce a new optimization framework to maximize the expected spread of cascades in networks. Our model allows a rich set of actions that directly manipulate cascade dy- namics by adding nodes or edges to the net- work. Our motivating application is one in spatial conservation planning, where a cas- cade models the dispersal of wild animals through a fragmented landscape. We propose a mixed integer programming (MIP) formu- lation that combines elements from network design and stochastic optimization. Our ap- proach results in solutions with stochastic op- timality guarantees and points to conserva- tion strategies that are fundamentally dier- ent from naive approaches.

  4. Spatial Organization of Enzyme Cascade on a DNA Origami Nanostructure.

    Science.gov (United States)

    Fu, Jinglin; Li, Tianran

    2017-01-01

    Self-assembled DNA nanostructures hold great promise to organize multi-enzyme systems with the precise control of the geometric arrangements. Enzymes modified with single-stranded DNA anchors are assembled onto the DNA origami tiles by hybridizing with the corresponding complementary strands displayed on the surface of the DNA nanostructures. Here, we describe a protocol of assembling a two-enzyme cascade on a discrete, rectangular DNA origami tile, where the distance between enzymes is precisely controlled for investigating the distance-dependent cascade activities.

  5. Aerodynamic Optimum Design of Transonic Turbine Cascades Using Genetic Algorithms

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    This paper presents an aerodynamic optimum design method for transonic turbine cascades based on the Genetic Algorithms coupled to the inviscid flow Euler Solver and the boundary-layer calculation.The Genetic Algorithms control the evolution of a population of cascades towards an optimum design.The fitness value of each string is evaluated using the flow solver.The design procedure has been developed and the behavior of the genetic algorithms has been tested.The objective functions of the design examples are the minimum mean-square deviation between the aimed pressure and computed pressure and the minimum amount of user expertise.

  6. Quantifying efficient information transduction of biochemical signaling cascades

    CERN Document Server

    Tsuruyama, Tatsuaki

    2016-01-01

    Cells can be considered as systems that utilize changes in thermodynamic entropy as information. Therefore, they serve as useful models for investigating the relationships between entropy production and information transmission, i.e., signal transduction. Based on the hypothesis that cells apply a chemical reaction cascade for the most efficient transduction of information, we adopted a coding design that minimizes the number of bits per concentration of molecules that are employed for information transduction. As a result, the average rate of entropy production is uniform across all cycles in a cascade reaction. Thus, the entropy production rate can be a valuable measure for the quantification of intracellular signal transduction.

  7. Protein-DNA computation by stochastic assembly cascade

    CERN Document Server

    Bar-Ziv, Roy; Libchaber, Albert; 10.1073/pnas.162369099

    2010-01-01

    The assembly of RecA on single-stranded DNA is measured and interpreted as a stochastic finite-state machine that is able to discriminate fine differences between sequences, a basic computational operation. RecA filaments efficiently scan DNA sequence through a cascade of random nucleation and disassembly events that is mechanistically similar to the dynamic instability of microtubules. This iterative cascade is a multistage kinetic proofreading process that amplifies minute differences, even a single base change. Our measurements suggest that this stochastic Turing-like machine can compute certain integral transforms.

  8. Analytic Approximation of Energy Resolution in Cascaded Gaseous Detectors

    Directory of Open Access Journals (Sweden)

    Dezső Varga

    2016-01-01

    Full Text Available An approximate formula has been derived for gain fluctuations in cascaded gaseous detectors such as Gas Electron Multipliers (GEMs, based on the assumption that the charge collection, avalanche formation, and extraction steps are independent cascaded processes. In order to test the approximation experimentally, a setup involving a standard GEM layer has been constructed to measure the energy resolution for 5.9 keV gamma particles. The formula reasonably traces both the charge collection and the extraction process dependence of the energy resolution. Such analytic approximation for gain fluctuations can be applied to multi-GEM detectors where it aids the interpretation of measurements as well as simulations.

  9. Coherent vortex structures and 3D enstrophy cascade

    CERN Document Server

    Dascaliuc, R

    2011-01-01

    Existence of 2D enstrophy cascade in a suitable mathematical setting, and under suitable conditions compatible with 2D turbulence phenomenology, is known both in the Fourier and in the physical scales. The goal of this paper is to show that the same geometric condition preventing the formation of singularities - 1/2-H\\"older coherence of the vorticity direction - coupled with a suitable condition on a modified Kraichnan scale, and under a certain modulation assumption on evolution of the vorticity, leads to existence of 3D enstrophy cascade in physical scales of the flow.

  10. Analytic approximation of energy resolution in cascaded gaseous detectors

    CERN Document Server

    Varga, Dezső

    2016-01-01

    An approximate formula has been derived for gain fluctuations in cascaded gaseous detectors such as GEM-s, based on the assumption that the charge collection, avalanche formation and extraction steps are independent cascaded processes. In order to test the approximation experimentally, a setup involving a standard GEM layer has been constructed to measure the energy resolution for 5.9 keV gamma particles. The formula reasonably traces both the charge collection as well as the extraction process dependence of the energy resolution. Such analytic approximation for gain fluctuations can be applied to multi-GEM detectors where it aids the interpretation of measurements as well as simulations.

  11. One-dimensional hydrodynamic model generating turbulent cascade

    CERN Document Server

    Matsumoto, Takeshi

    2016-01-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analogue (enstrophy) in the inviscid case. With a large-scale forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency and self-similarity in the dynamical system structure.

  12. Stability and Stabilization of Block-cascading Switched Linear Systems

    Institute of Scientific and Technical Information of China (English)

    Ya-Hong Zhu; Dai-Zhan Cheng

    2006-01-01

    The main purpose of this paper is to investigate the problem of quadratic stability and stabilization in switched linear systems using reducible Lie algebra. First, we investigate the structure of all real invariant subspaces for a given linear system. The result is then used to provide a comparable cascading form for switching models. Using the commoncascading form, a common quadratic Lyapunov function is (QLFs) is explored by finding common QLFs of diagonal blocks.In addition, a cascading Quaker Lemma is proved. Combining it with stability results, the problem of feedback stabilization for a class of switched linear systems is solved.

  13. Applications of absorption spectroscopy using quantum cascade lasers.

    Science.gov (United States)

    Zhang, Lizhu; Tian, Guang; Li, Jingsong; Yu, Benli

    2014-01-01

    Infrared laser absorption spectroscopy (LAS) is a promising modern technique for sensing trace gases with high sensitivity, selectivity, and high time resolution. Mid-infrared quantum cascade lasers, operating in a pulsed or continuous wave mode, have potential as spectroscopic sources because of their narrow linewidths, single mode operation, tunability, high output power, reliability, low power consumption, and compactness. This paper reviews some important developments in modern laser absorption spectroscopy based on the use of quantum cascade laser (QCL) sources. Among the various laser spectroscopic methods, this review is focused on selected absorption spectroscopy applications of QCLs, with particular emphasis on molecular spectroscopy, industrial process control, combustion diagnostics, and medical breath analysis.

  14. Seeded QED cascades in counter propagating laser pulses

    CERN Document Server

    Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo; Silva, Luís O

    2015-01-01

    The growth rates of seeded QED cascades in counter propagating lasers are calculated with 2D/3D QED-PIC simulations. The dependence of the growth rate on laser polarisation and intensity are compared with analytical models that support simulations results. The models provide an insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. The results suggest that relativistic pair plasmas and efficient conversion from laser photons to gamma rays can be created with the typical intensities planned to operate on future ultra-intense laser facilities such as ELI or VULCAN.

  15. Rate equation modelling and investigation of quantum cascade detector characteristics

    Science.gov (United States)

    Saha, Sumit; Kumar, Jitendra

    2016-10-01

    A simple precise transport model has been proposed using rate equation approach for the characterization of a quantum cascade detector. The resonant tunneling transport is incorporated in the rate equation model through a resonant tunneling current density term. All the major scattering processes are included in the rate equation model. The effect of temperature on the quantum cascade detector characteristics has been examined considering the temperature dependent band parameters and the carrier scattering processes. Incorporation of the resonant tunneling process in the rate equation model improves the detector performance appreciably and reproduces the detector characteristics within experimental accuracy.

  16. Cascade adaptive control of uncertain unified chaotic systems

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Li Dong-Hai; Wang Jing

    2011-01-01

    The chaos control of uncertain unified chaotic systems is considered. Cascade adaptive control approach with only one control input is presented to stabilize states of the uncertain unified chaotic system at the zero equilibrium point.Since an adaptive controller based on dynamic compensation mechanism is employed, the exact model of the unified chaotic system is not necessarily required.By choosing appropriate controller parameters, chaotic phenomenon can be suppressed and the response speed is tunable. Sufficient condition for the asymptotic stability of the approach is derived. Numerical simulation results confirm that the cascade adaptive control approach with only one control signal is valid in chaos control of uncertain unified chaotic systems.

  17. TEMPORAL OPTICAL SOLITONS VIA MULTISTEP x(2) CASCADING

    Institute of Scientific and Technical Information of China (English)

    HUANG GUO-XIANG

    2001-01-01

    We consider a multistep X(2) cascading for light pulses with the dispersion of the system taken into account. Using the method of multiple scales we derive a set of coupled envelope equations governing the nonlinear evolution of the fundamental, second and third harmonic waves involved simultaneously in two nonlinear optical processes, i.e. second harmonic generation and sum frequency mixing. We show that three-wave temporal optical solitons are possible in three- and four-step cascading in the presence of a group-velocity mismatch between different pulses.

  18. Cascading Failures in Networks: Inference, Intervention and Robustness to WMDs

    Science.gov (United States)

    2016-08-01

    8725 John J. Kingman Road, MS 6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-16-83 Cascading Failures in Networks ...aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services ...Austin   Project  Title:  Cascading  Failures  in   Networks :  Inference,  Intervention  and  Robustness  to   WMDs   What  are  the  major  goals  of

  19. Displacement cascades and defect annealing in tungsten, Part II: Object kinetic Monte Carlo simulation of tungsten cascade aging

    Energy Technology Data Exchange (ETDEWEB)

    Nandipati, Giridhar, E-mail: giridhar.nandipati@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States); Setyawan, Wahyu; Heinisch, Howard L. [Pacific Northwest National Laboratory, Richland, WA (United States); Roche, Kenneth J. [Pacific Northwest National Laboratory, Richland, WA (United States); Department of Physics, University of Washington, Seattle, WA 98195 (United States); Kurtz, Richard J. [Pacific Northwest National Laboratory, Richland, WA (United States); Wirth, Brian D. [University of Tennessee, Knoxville, TN (United States)

    2015-07-15

    The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.

  20. Displacement cascades and defect annealing in tungsten, Part II: Object kinetic Monte Carlo Simulation of Tungsten Cascade Aging

    Energy Technology Data Exchange (ETDEWEB)

    Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

    2015-07-01

    The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.

  1. Atmospheric composition change: Ecosystems-Atmosphere interactions

    NARCIS (Netherlands)

    Fowler, D.; Pilegaard, K.; Sutton, M.A.; Ambus, P.; Raivonen, M.; Duyzer, J.; Simpson, D.; Fagerli, H.; Fuzzi, S.; Schjoerring, J.K.; Granier, C.; Neftel, A.; Isaksen, I.S.A.; Laj, P.; Maione, M.; Monks, P.S.; Burkhardt, J.; Daemmgen, U.; Neirynck, J.; Personne, E.; Wichink Kruit, R.J.; Butterbach-Bahl, K.; Flechard, C.; Tuovinen, J.P.; Coyle, M.; Gerosa, G.; Loubet, B.; Altimir, N.; Gruenhage, L.; Ammann, C.; Cieslik, S.; Paoletti, E.; Mikkelsen, T.N.; Ro-Poulsen, H.; Cellier, P.; Cape, J.N.; Horvath, L.; Loreto, F.; Niinemets, U.; Palmer, P.I.; Rinne, J.; Misztal, P.; Nemitz, E.; Nilsson, D.; Pryor, S.; Gallagher, M.W.; Vesala, T.; Skiba, U.; Brueggemann, N.; Zechmeister-Boltenstern, S.; Williams, J.; O'Dowd, C.; Facchini, M.C.; Leeuw, de G.; Flossman, A.; Chaumerliac, N.; Erisman, J.W.

    2009-01-01

    Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O-3, CH4, N2O and particles i

  2. DNA binding properties of the small cascade subunit Csa5.

    Directory of Open Access Journals (Sweden)

    Michael Daume

    Full Text Available CRISPR-Cas systems provide immunity against viral attacks in archaeal and bacterial cells. Type I systems employ a Cas protein complex termed Cascade, which utilizes small CRISPR RNAs to detect and degrade the exogenic DNA. A small sequence motif, the PAM, marks the foreign substrates. Previously, a recombinant type I-A Cascade complex from the archaeon Thermoproteus tenax was shown to target and degrade DNA in vitro, dependent on a native PAM sequence. Here, we present the biochemical analysis of the small subunit, Csa5, of this Cascade complex. T. tenax Csa5 preferentially bound ssDNA and mutants that showed decreased ssDNA-binding and reduced Cascade-mediated DNA cleavage were identified. Csa5 oligomerization prevented DNA binding. Specific recognition of the PAM sequence was not observed. Phylogenetic analyses identified Csa5 as a universal member of type I-A systems and revealed three distinct groups. A potential role of Csa5 in R-loop stabilization is discussed.

  3. Chaotic Cascades for D-branes on Singularities

    CERN Document Server

    Franco, S; Herzog, C; Walcher, J; Franco, Sebastian; He, Yang-Hui; Herzog, Christopher; Walcher, Johannes

    2004-01-01

    We briefly review our work on the cascading renormalization group flows for gauge theories on D-branes probing Calabi-Yau singularities. Such RG flows are sometimes chaotic and exhibit duality walls. We construct supergravity solutions dual to logarithmic flows for these theories. We make new observations about a surface of conformal theories and more complicated supergravity solutions.

  4. Network protection against worms and cascading failures using modularity partitioning

    NARCIS (Netherlands)

    Omic, J.; Hernandez, J.M.; Van Mieghem, P.

    2010-01-01

    Communication networks are prone to virus and worms spreading and cascading failures. Recently, a number of social networking worms have spread over public Web sites. Another example is error propagation in routing tables, such as in BGP tables. The immunization and error curing applied to these sce

  5. Laser-Pulse-Shape Control of Seeded QED Cascades

    CERN Document Server

    Tamburini, Matteo; Keitel, Christoph H

    2015-01-01

    The emergence of electron-positron cascades via ultrastrong electromagnetic fields constitutes a prominent manifestation of the complex interplay between strong-field QED processes and multiparticle dynamics. Here the onset and development of electron-positron cascades are investigated in the head-on collision of two realistic tightly focused ultraintense optical laser pulses in a tenuous gas. As a consequence of the large ponderomotive forces expelling all electrons of the gas from the focal volume, we demonstrate that the onset of QED cascades may be prevented even at intensities around $10^{26}\\;\\text{W/cm$^2$}$ by focusing the laser energy almost down to the diffraction limit. Alternatively, a well controlled development of a QED cascade may be facilitated at laser intensities below $10^{24}\\;\\text{W/cm$^2$}$ per beam by enlarged focal areas and a rapid rise of the pulse or at total powers near $20\\;\\text{PW}$ by employing suitable high-$Z$ gases.

  6. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes....... Numerical results for the capacities are presented....

  7. Thresholds and Complex Dynamics of Interdependent Cascading Infrastructure Systems

    Science.gov (United States)

    Carreras, B. A.; Newman, D. E.; Dobson, I.; Lynch, V. E.; Gradney, Paul

    Critical infrastructures have a number of the characteristic properties of complex systems. Among these are infrequent large failures through cascading events. These events, though infrequent, often obey a power law distribution in their probability versus size which suggests that conventional risk analysis does not apply to these systems. Real infrastructure systems typically have an additional layer of complexity, namely the heterogeneous coupling to other infrastructure systems that can allow a failure in one system to propagate to the other system. Here, we model the infrastructure systems through a network with complex system dynamics. We use both mean field theory to get analytic results and a numerical complex systems model, Demon, for computational results. An isolated system has bifurcated fixed points and a cascading threshold which is the same as the bifurcation point. When systems are coupled, this is no longer true and the cascading threshold is different from the bifurcation point of the fixed point solutions. This change in the cascading threshold caused by the interdependence of the system can have an impact on the "safe operation" of interdependent infrastructure systems by changing the critical point and even the power law exponent.

  8. Cascading A*: a Parallel Approach to Approximate Heuristic Search

    OpenAIRE

    Gu, Yan

    2014-01-01

    In this paper, we proposed a new approximate heuristic search algorithm: Cascading A*, which is a two-phrase algorithm combining A* and IDA* by a new concept "envelope ball". The new algorithm CA* is efficient, able to generate approximate solution and any-time solution, and parallel friendly.

  9. A psychological cascade model for persisting voice problems in teachers

    NARCIS (Netherlands)

    de Jong, FICRS; Cornelis, BE; Wuyts, FL; Kooijman, PGC; Schutte, HK; Oudes, MJ; Graamans, K

    2003-01-01

    In 76 teachers with persisting voice problems, the maintaining factors and coping strategies were examined. Physical, functional, psychological and socioeconomic factors were assessed. A parallel was drawn to a psychological cascade model designed for patients with chronic back pain. The majority of

  10. On the cascade approach to the quantum multiscattering problem

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, L.L. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)

    2003-01-01

    The multiscattering problem is studied in the matrix density formalism. We study how to isolate the quasi-classical degrees of freedom in order to connect them with a cascade approach. The different problems that arise, as well as their possible solutions, are discussed and exemplified with a pion-nucleus model. (orig.)

  11. CASCADIC MULTIGRID FOR FINITE VOLUME METHODS FOR ELLIPTIC PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Zhong-ci Shi; Xue-jun Xu; Hong-ying Man

    2004-01-01

    In this paper, some effective cascadic multigrid methods are proposed for solving the large scale symmetric or nonsymmetric algebraic systems arising from the finite volumemethods for second order elliptic problems. Its is shown that these algorithms are optimal in both accuracy and computational complexity. Numerical expermients are repored to support out theory.

  12. Calculating Node Importance Considering Cascading Failure in Traffic Networks

    Directory of Open Access Journals (Sweden)

    Zhengwu Wang

    2013-01-01

    Full Text Available The traffic network is a scale-free network. In selective attack, invalidation of few key nodes may lead to network failure so it is important to find these key nodes. In this study, the key nodes are determined by establishing calculating methods of node importance based on cascading failure behaviors. First, a cascading failure model of traffic network is posed. Its differences from current models are as follows: 1 The upper travel network and lower road network are influenced each other, 2 Capacity of nodes and links are given at first but not in direct proportion to initial flow that is related to initial capacity, 3 Travel time is used to describe status of links, 4 Capacity of links may change. The evaluation method of node importance of traffic network considering cascading failure is proposed then based on node deletion. It uses congestion status of cascading failure network to describe the node importance and algorithm procedures are designed to estimate importance of all nodes. At the end, the experiment analysis shows that network structure and traveler behaviors have in significant influence on node importance.

  13. Optical Pulse Generation with Self-Cascaded Electroabsorption Modulator

    Institute of Scientific and Technical Information of China (English)

    WU Jian; QiU Ji-Fang; ZHOU Guang-Tao; XU Kun; LIN Jin-Tong

    2007-01-01

    A novel scheme for pulse generation with a self-cascaded electroabsorption modulator is presented and experi mentally demonstrated at 10 GHz.In the case of optimal tuning of time delay in the fibre loop,the improvement of 50% on pulsewidth with improved extinction ratio is obtained and the narrowest pulse generated with this method is about 11 ps.

  14. Cascades on a stochastic pulse-coupled network.

    Science.gov (United States)

    Wray, C M; Bishop, S R

    2014-09-12

    While much recent research has focused on understanding isolated cascades of networks, less attention has been given to dynamical processes on networks exhibiting repeated cascades of opposing influence. An example of this is the dynamic behaviour of financial markets where cascades of buying and selling can occur, even over short timescales. To model these phenomena, a stochastic pulse-coupled oscillator network with upper and lower thresholds is described and analysed. Numerical confirmation of asynchronous and synchronous regimes of the system is presented, along with analytical identification of the fixed point state vector of the asynchronous mean field system. A lower bound for the finite system mean field critical value of network coupling probability is found that separates the asynchronous and synchronous regimes. For the low-dimensional mean field system, a closed-form equation is found for cascade size, in terms of the network coupling probability. Finally, a description of how this model can be applied to interacting agents in a financial market is provided.

  15. Detecting Early Signatures of Persuasion in Information Cascades

    Science.gov (United States)

    2014-01-01

    ADDRESS. Indiana University at Bloomington Trustees of Indiana University 509 E 3RD ST Bloomington, IN 47401 -3654 Detecting Early Signatures of Persuasion ...SMISC  Project:   DESPIC:  Detecting  Early  Signatures  of   Persuasion  in  Information  Cascades     Teams:   Indiana

  16. Common features at the start of the neurodegeneration cascade

    OpenAIRE

    Rubén Hervás; Javier Oroz; Albert Galera-Prat; Oscar Goñi; Alejandro Valbuena; Andrés M Vera; Angel Gómez-Sicilia; Fernando Losada-Urzáiz; Uversky, Vladimir N.; Margarita Menéndez; Laurents, Douglas V.; Marta Bruix; Mariano Carrión-Vázquez

    2012-01-01

    Amyloidogenic neurodegenerative diseases are incurable conditions with high social impact that are typically caused by specific, largely disordered proteins. However, the underlying molecular mechanism remains elusive to established techniques. A favored hypothesis postulates that a critical conformational change in the monomer (an ideal therapeutic target) in these >neurotoxic proteins> triggers the pathogenic cascade. We use force spectroscopy and a novel methodology for unequivocal single-...

  17. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yang; Liu Yuan; Gao Dingshan, E-mail: dsgao@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-01

    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  18. Successful Treatment Of Homozygous Familial Hypercholesterolemia Using Cascade Filtration Plasmapheresis

    Directory of Open Access Journals (Sweden)

    Fatih Kardas

    2012-12-01

    Full Text Available OBJECTIVE: The aim of our study is to discuss the efficacy of low-density lipoprotein-cholesterol (LDL-C apheresis procedure using the cascade filtration system for pediatric patients with homozygous familial hypercholesterolemia (FH, and to clarify the adverse effects and difficulties. METHODS: LDL apheresis using the cascade filtration system was performed in 3 pediatric patients with homozygous FH. In total, 120 apheresis sessions were performed for all patients. RESULTS: Cascade filtration therapy significantly reduced the mean LDL-C values from 418 ± 62 mg/dl to 145 ± 43 mg/dl (p<0.05. We determined an acute mean reduction in the plasma levels of total cholesterol (57.9%, LDL cholesterol (70.8%, and high-density lipoprotein (HDL cholesterol (40.7%. Treatments were well tolerated. The most frequent clinical adverse effects were hypotension in 3 sessions (2.5%, chills/feeling cold (1.7% in 2 sessions, and nausea and vomiting in 3 sessions (2.5%. CONCLUSION: Our experience with three patients using the cascade filtration system were, good clinical outcomes, laboratory findings, safety of usage, minor adverse effects and technical problems.

  19. Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun

    in different power flow directions, a bidirectional impedance control method is also proposed to unify and improve the system stability. Control system type number is also analyzed in this thesis, then a symmetric proportional control method for the two stage cascaded converter is proposed to reduce the dc...

  20. Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    more uncertainty to the system stability. An investigation is performed here for showing that the forward and reverse interactions are prominently different in terms of dynamics and stability even though the cascaded converter control remains unchanged. An important guideline has been drawn...

  1. Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS

    Science.gov (United States)

    Archambault, S.; Archer, A.; Benbow, W.; Buchovecky, M.; Bugaev, V.; Cerruti, M.; Connolly, M. P.; Cui, W.; Falcone, A.; Fernández Alonso, M.; Finley, J. P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Griffin, S.; Hütten, M.; Hervet, O.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Lin, T. T. Y.; Maier, G.; McArthur, S.; Moriarty, P.; Nieto, D.; O’Brien, S.; Ong, R. A.; Otte, A. N.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rovero, A. C.; Sadeh, I.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tyler, J.; Wakely, S. P.; Weinstein, A.; Weisgarber, T.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

    2017-02-01

    We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron–positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron–positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10‑14 G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission.

  2. Dispersive waves in fs cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2009-01-01

    Dispersive waves are observed in simulations of cascaded (phase-mismatched) second-harmonic generation. When generating ultra-short fs compressed near-IR solitons the dispersive waves are strongly red-shifted, depending on the soliton wavelength. Semi-analytical calculations predict the wavelengths....

  3. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

    NARCIS (Netherlands)

    Reyes Reyes, A.; Hou, Z.; Van Mastrigt, E.; Horsten, R.C.; De Jongste, J.C.; Pijnenburg, M.W.; Urbach, H.P.; Bhattacharya, N.

    2014-01-01

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm−1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present

  4. Production and Searches for Cascade Baryons with CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Elton

    2010-01-01

    We present the results of photoproduction cross sections of the ground state cascade $\\Xi^-$ and the first excited state $\\Xi^{*-}(1530)$ measured with the CLAS detector. The photoproduction of the cascade resonances has been investigated in the reactions $\\gamma p \\rightarrow K^+K^+(X)$ and $\\gamma p \\rightarrow K^+K^+\\pi^-(X)$. The differential and total cross sections of the $\\Xi^{-}$ were determined for photon beam energies from 2.75 to 4.75 GeV and are consistent with a production mechanism of $Y^* \\rightarrow K^+ \\Xi^-$ through a t-channel process. The cross-section of the $\\Xi^{*-}(1530)$ has been determined for photon beam energies from 3.35 to 4.75 GeV. The reaction $\\gamma p \\rightarrow K^+K^+ \\pi^- (\\Xi^0)$ has also been investigated to search for excited cascade resonances decaying to $\\pi^- \\Xi^0$. No significant signal of excited cascade states other than the well-known $\\Xi^{*-}(1530)$ is observed. We also present the latest results of a search for the $\\Phi^{--}$(1862) exotic pentaquark state in a photoproduction experiment on a deuterium target. A high-statistics sample of $\\pi^-\\Xi^-$ events have been collected and analyzed. A preliminary invariant mass spectrum of the $\\pi^-\\Xi^-$ system is presented, which is used to set upper limits on the photoproduction of the $\\Phi^{--}$ pentaquark state.

  5. An Algebraic Approach to Signaling Cascades with n Layers

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Knudsen, Michael; Andersen, Lars Nørvang;

    2011-01-01

    Posttranslational modification of proteins is key in transmission of signals in cells. Many signaling pathways contain several layers of modification cycles that mediate and change the signal through the pathway. Here, we study a simple signaling cascade consisting of n layers of modification...

  6. Vortex merging and spectral cascade in two-dimensional flows

    DEFF Research Database (Denmark)

    Nielsen, A.H.; He, X.; Juul Rasmussen, J.;

    1996-01-01

    The merging of two identical vortices is studied numerically using a spectral code. It is noted that the enstrophy cascade is most active on the distorted vortex boundaries, with a Kolmogorov-like spectrum E(k) approximate to k(-alpha), alpha less than or equal to 4, developed at high wave numbers...

  7. Turbulence characteristics in a supersonic cascade wake flow

    Energy Technology Data Exchange (ETDEWEB)

    Andrew, P.L.; Ng, W.F. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1994-10-01

    The turbulent character of the supersonic wake of a linear cascade of fan airfoils has been studied using a two-component laser-doppler anemometer. The cascade was tested in the Virginia Polytechnic Institute and State University intermittent wind tunnel facility, where the Mach and Reynolds numbers were 2.36 and 4.8 [times] 10[sup 6], respectively. In addition to mean flow measurements, Reynolds normal and shear stresses were measured as functions of cascade incidence angle and streamwise locations spanning the near-wake and the far-wake. The extremities of profiles of both the mean and turbulent wake properties were found to be strongly influenced by upstream shock-boundary-layer interactions, the strength of which varied with cascade incidence. In contrast, the peak levels of turbulence properties within the shear layer were found to be largely independent of incidence, and could be characterized in terms of the streamwise position only. The velocity defect turbulence level was found to be 23%, and the generally accepted value of the turbulence structural coefficient of 0.30 was found to be valid for this flow. The degree of similarity of the mean flow wake profiles was established, and those profiles demonstrating the most similarity were found to approach a state of equilibrium between the mean and turbulent properties. In general, this wake flow may be described as a classical free shear flow, upon which the influence of upstream shock-boundary-layer interactions has been superimposed.

  8. Efficient Design of Multi-stage Cascade Waveband Separator

    Institute of Scientific and Technical Information of China (English)

    Samrat Ganguly; Rauf Izmailov; Nan Tu; Ting Wang

    2003-01-01

    We propose a cascade system of filters for realizing a non-uniform waveband separation for optical networks. The use of such separation is required at the DEMUX stage in a optical OXC switching wavebands. The design of the system is based on optimized balanced tree, which minimizes the overall optical loss.

  9. Emergence of a turbulent cascade in a quantum gas

    Science.gov (United States)

    Navon, Nir; Gaunt, Alexander L.; Smith, Robert P.; Hadzibabic, Zoran

    2016-11-01

    A central concept in the modern understanding of turbulence is the existence of cascades of excitations from large to small length scales, or vice versa. This concept was introduced in 1941 by Kolmogorov and Obukhov, and such cascades have since been observed in various systems, including interplanetary plasmas, supernovae, ocean waves and financial markets. Despite much progress, a quantitative understanding of turbulence remains a challenge, owing to the interplay between many length scales that makes theoretical simulations of realistic experimental conditions difficult. Here we observe the emergence of a turbulent cascade in a weakly interacting homogeneous Bose gas—a quantum fluid that can be theoretically described on all relevant length scales. We prepare a Bose-Einstein condensate in an optical box, drive it out of equilibrium with an oscillating force that pumps energy into the system at the largest length scale, study its nonlinear response to the periodic drive, and observe a gradual development of a cascade characterized by an isotropic power-law distribution in momentum space. We numerically model our experiments using the Gross-Pitaevskii equation and find excellent agreement with the measurements. Our experiments establish the uniform Bose gas as a promising new medium for investigating many aspects of turbulence, including the interplay between vortex and wave turbulence, and the relative importance of quantum and classical effects.

  10. Experimental investigation on a high subsonic compressor cascade flow

    Directory of Open Access Journals (Sweden)

    Zhang Haideng

    2015-08-01

    Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

  11. CASCADIC MULTIGRID METHOD FOR THE MORTAR ELEMENT METHOD FOR P1 NONCONFORMING ELEMENT

    Institute of Scientific and Technical Information of China (English)

    Chun-jia Bi; Dan-hui Hong

    2005-01-01

    In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optimal complexity.

  12. Hydrothermal heat discharge in the Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, S.E.; Mariner, R.H.

    2010-01-01

    Hydrothermal heat discharge in the Cascade Range includes the heat discharged by thermal springs, by "slightly thermal" springs that are only a few degrees warmer than ambient temperature, and by fumaroles. Thermal-spring heat discharge is calculated on the basis of chloride-flux measurements and geothermometer temperatures and totals ~ 240 MW in the U.S. part of the Cascade Range, excluding the transient post-1980 discharge at Mount St. Helens (~80 MW as of 2004-5). Heat discharge from "slightly thermal" springs is based on the degree of geothermal warming (after correction for gravitational potential energy effects) and totals ~. 660. MW. Fumarolic heat discharge is calculated by a variety of indirect and direct methods and totals ~160 MW, excluding the transient mid-1970s discharge at Mount Baker (~80 MW) and transient post-1980 discharge at Mount St. Helens (>. 230. MW as of 2005). Other than the pronounced transients at Mount St. Helens and Mount Baker, hydrothermal heat discharge in the Cascade Range appears to be fairly steady over a ~25-year period of measurement. Of the total of ~. 1050. MW of "steady" hydrothermal heat discharge identified in the U.S. part of the Cascade Range, less than 50. MW occurs north of latitude 45??15' N (~0.1 MW per km arc length from 45??15' to 49??N). Much greater rates of hydrothermal heat discharge south of 45??15'N (~1.7 MW per km arc length from 40?? to 45??15'N) may reflect the influence of Basin and Range-style extensional tectonics (faulting) that impinges on the Cascades as far north as Mount Jefferson but is not evident farther north. ?? 2010.

  13. Structure of the archaeal Cascade subunit Csa5

    Science.gov (United States)

    Reeks, Judith; Graham, Shirley; Anderson, Linzi; Liu, Huanting; White, Malcolm F.; Naismith, James H.

    2013-01-01

    The Cascade complex for CRISPR-mediated antiviral immunity uses CRISPR RNA (crRNA) to target invading DNA species from mobile elements such as viruses, leading to their destruction. The core of the Cascade effector complex consists of the Cas5 and Cas7 subunits, which are widely conserved in prokaryotes. Cas7 binds crRNA and forms the helical backbone of Cascade. Many archaea encode a version of the Cascade complex (denoted Type I-A) that includes a Csa5 (or small) subunit, which interacts weakly with the core proteins. Here, we report the crystal structure of the Csa5 protein from Sulfolobus solfataricus. Csa5 comprises a conserved α-helical domain with a small insertion consisting of a weakly conserved β-strand domain. In the crystal, the Csa5 monomers have multimerized into infinite helical threads. At each interface is a strictly conserved intersubunit salt bridge, deletion of which disrupts multimerization. Structural analysis indicates a shared evolutionary history among the small subunits of the CRISPR effector complexes. The same α-helical domain is found in the C-terminal domain of Cse2 (from Type I-E Cascade), while the N-terminal domain of Cse2 is found in Cmr5 of the CMR (Type III-B) effector complex. As Cmr5 shares no match with Csa5, two possibilities present themselves: selective domain loss from an ancestral Cse2 to create two new subfamilies or domain fusion of two separate families to create a new Cse2 family. A definitive answer awaits structural studies of further small subunits from other CRISPR effector complexes. PMID:23846216

  14. Nitric Oxide and Prostaglandins Potentiate the Liver Regeneration Cascade

    Directory of Open Access Journals (Sweden)

    Jodi M Schoen Smith

    2006-01-01

    Full Text Available The liver has the remarkable ability to regenerate following damage or surgical resection. Although this feature of the liver has been studied for over 100 years, the trigger of the liver regeneration cascade remains controversial. Recent experimental evidence supports the hypothesis that nitric oxide (NO and prostaglandins (PGs, released secondary to an increase in the blood flow-to-liver mass ratio following two-thirds partial hepatectomy (PHx, work synergistically to trigger liver regeneration. To extend this research, the hypothesis that NO and PGs are potential therapeutic targets to potentiate the liver regeneration cascade is tested. The NO donor s-nitroso-n-acetylpenicillamine, the phosphodiesterase V antagonist zaprinast (ZAP and PGI2 each potentiated c-fos messenger RNA expression, an index of initiation of the liver regeneration cascade, following PHx. Also, the triple combination of s-nitroso-n-acetylpenicillamine, ZAP and PGI2 potentiated c-fos messenger RNA expression. These results support the hypothesis that NO and PGs can potentiate initiation of the regeneration cascade. An additional index of liver weight restoration 48 h after PHx was also used to test the hypothesis, because this index encompasses the entire liver regeneration cascade. ZAP and 6-keto-PGF1α, a stable metabolite of PGI2, and the combination of ZAP and 6-keto-PGF1α, each potentiated liver weight restoration 48 h after PHx. These results also provide support for the hypothesis that NO and PGs are possible therapeutic targets to potentiate liver regeneration following surgical resection.

  15. A hidden feedback in signaling cascades is revealed.

    Directory of Open Access Journals (Sweden)

    Alejandra C Ventura

    2008-03-01

    Full Text Available Cycles involving covalent modification of proteins are key components of the intracellular signaling machinery. Each cycle is comprised of two interconvertable forms of a particular protein. A classic signaling pathway is structured by a chain or cascade of basic cycle units in such a way that the activated protein in one cycle promotes the activation of the next protein in the chain, and so on. Starting from a mechanistic kinetic description and using a careful perturbation analysis, we have derived, to our knowledge for the first time, a consistent approximation of the chain with one variable per cycle. The model we derive is distinct from the one that has been in use in the literature for several years, which is a phenomenological extension of the Goldbeter-Koshland biochemical switch. Even though much has been done regarding the mathematical modeling of these systems, our contribution fills a gap between existing models and, in doing so, we have unveiled critical new properties of this type of signaling cascades. A key feature of our new model is that a negative feedback emerges naturally, exerted between each cycle and its predecessor. Due to this negative feedback, the system displays damped temporal oscillations under constant stimulation and, most important, propagates perturbations both forwards and backwards. This last attribute challenges the widespread notion of unidirectionality in signaling cascades. Concrete examples of applications to MAPK cascades are discussed. All these properties are shared by the complete mechanistic description and our simplified model, but not by previously derived phenomenological models of signaling cascades.

  16. Human-induced trophic cascades along the fecal detritus pathway.

    Directory of Open Access Journals (Sweden)

    Elizabeth Nichols

    Full Text Available Human presence and activity in tropical forest is thought to exert top-down regulation over the various 'green-world' pathways of plant-based foodwebs. However, these effects have never been explored for the 'brown-world' pathways of fecal-detritus webs. The strong effects of humans on tropical game mammals are likely to indirectly influence fecal detritivores (including Scarabaeine dung beetles, with subsequent indirect impacts on detrivore-mediated and plant-facilitating detrital processes. Across a 380-km gradient of human influence in the western Brazilian Amazon, we conducted the first landscape-level assessment of human-induced cascade effects on the fecal detritus pathway, by coupling data on human impact, game mammal and detritivore community structure, and rate measurements of a key detritus process (i.e. dung beetle-mediated secondary seed dispersal. We found evidence that human impact indirectly influences both the diversity and biomass of fecal detritivores, but not detritivore-mediated processes. Cascade strength varied across detritivore groups defined by species' traits. We found smaller-bodied dung beetles were at higher risk of local decline in areas of human presence, and that body size was a better predictor of cascade structure than fecal resource manipulation strategy. Cascade strength was also stronger in upland, unflooded forests, than in seasonally flooded forests. Our results suggest that the impact of human activity in tropical forest on fecal-detritus food web structure is mediated by both species' traits and habitat type. Further research will be required to determine the conditions under which these cascade effects influence fecal-detritus web function.

  17. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    OpenAIRE

    Arash Toudeshki; Norman Mariun; Hashim Hizam; Noor Izzri Abdul Wahab

    2014-01-01

    For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

  18. Development of GaN/AlGaN Terahertz Quantum Cascade Laser

    Science.gov (United States)

    2008-11-19

    AFOSR-Taiwan Nanoscience Initiative Project Final Report Project Title Development of GaN /AlGaN Terahertz Quantum Cascade Laser...DATES COVERED 14-06-2007 to 13-06-2008 4. TITLE AND SUBTITLE Development of GaN -Based Terahertz Quantum Cascade Laser 5a. CONTRACT NUMBER...the GaN /AlGaN active region for terahertz quantum cascade lasers using MOCVD system based on the quantum cascade structure proposed by Prof. Greg Sun

  19. Obtaining statistics of cascading line outages spreading in an electric transmission network from standard utility data

    CERN Document Server

    Dobson, Ian

    2015-01-01

    We show how to use standard transmission line outage historical data to obtain the network topology in such a way that cascades of line outages can be easily located on the network. Then we obtain statistics quantifying how cascading outages typically spread on the network. Processing real outage data is fundamental for understanding cascading and for evaluating the validity of the many different models and simulations that have been proposed for cascading in power networks.

  20. Mirador - Atmospheric Composition

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. Atmospheric Composition is focused on the composition of Earth's atmosphere in relation to climate prediction, solar effects,...

  1. Planetary Atmospheric Electricity

    CERN Document Server

    Leblanc, F; Yair, Y; Harrison, R. G; Lebreton, J. P; Blanc, M

    2008-01-01

    This volume presents our contemporary understanding of atmospheric electricity at Earth and in other solar system atmospheres. It is written by experts in terrestrial atmospheric electricity and planetary scientists. Many of the key issues related to planetary atmospheric electricity are discussed. The physics presented in this book includes ionisation processes in planetary atmospheres, charge generation and separation, and a discussion of electromagnetic signatures of atmospheric discharges. The measurement of thunderstorms and lightning, including its effects and hazards, is highlighted by articles on ground and space based instrumentation, and new missions.Theory and modelling of planetary atmospheric electricity complete this review of the research that is undertaken in this exciting field of space science. This book is an essential research tool for space scientists and geoscientists interested in electrical effects in atmospheres and planetary systems. Graduate students and researchers who are new to t...

  2. Our shared atmosphere

    Science.gov (United States)

    Our atmosphere is a precious and fascinating resource, providing air to breath, shielding us from harmful ultraviolet radiation (UV), and maintaining a comfortable climate. Since the industrial revolution, people have significantly altered the composition of the atmosphere throu...

  3. Prediction and Control of Network Cascade: Example of Power Grid or Networking Adaptability from WMD Disruption and Cascading Failures

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory

    2012-07-24

    The goal of the DTRA project is to develop a mathematical framework that will provide the fundamental understanding of network survivability, algorithms for detecting/inferring pre-cursors of abnormal network behaviors, and methods for network adaptability and self-healing from cascading failures.

  4. DECREASING OF WATER TROPHY IN CASCADE SYSTEMS, ON EXAMPLE OF THE SOŁA RIVER DAM CASCADE (SOUTHERN POLAND

    Directory of Open Access Journals (Sweden)

    Ewa Jachniak

    2014-10-01

    Full Text Available In this thesis the subject of water self-purification in cascade systems of water reservoirs was engaged. The results of hydrobiological research of three dam reservoirs (Tresna, Porąbka and Czaniec, creating the Soła river dam cascade were presented. The trophic status of these reservoirs was defined on the grounds of the concentration of chlorophyll a, biomass of phytoplankton and occurrence of indicating species of planktonic algae. The results of research indicated on decreasing of water trophy in the layout from the highest into the lowest reservoir of the cascade. The average concentrations of chlorophyll a amounted appropriately 19,99 μg·dm-3, 8,74 μg·dm-3 and 4,29 μg·dm-3, instead the average biomass of phytoplankton amounted appropriately 4,1 mg·dm-3, 3,4 mg·dm-3 and 0,1 mg·dm-3. The observed species of algae confirmed occurrence of differences between reservoirs. In Tresna reservoir more species of phytoplankton indicating for eutrophy were thrived, instead in Porąbka and Czaniec reservoirs the species occurring in oligomesotrophic water thrived. Water self-purification in the Soła river dam cascade expressed decreasing of their fertility is important for water management of the region, because the Czaniec reservoir fulfill a function of water-supply reservoir.

  5. 77 FR 73651 - Cascade Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2012-12-11

    ... No. 14464-000] Cascade Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for..., Cascade Energy Storage, LLC, filed an application for a preliminary permit, pursuant to section 4(f) of... Executive Officer, Cascade Energy Storage, LLC, 1210 W. Franklin Street, Ste. 2, Boise, Idaho 83702;...

  6. Single phase cascaded H5 inverter with leakage current elimination for transformerless photovoltaic system

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Jia, X.; Lu, Z.;

    2016-01-01

    Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H...

  7. Interband cascade light emitting devices based on type-II quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q.; Lin, C.H.; Murry, S.J. [Univ. of Houston, TX (United States). Space Vacuum Epitaxy Center] [and others

    1997-06-01

    The authors discuss physical processes in the newly developed type-II interband cascade light emitting devices, and review their recent progress in the demonstration of the first type-II interband cascade lasers and the observation of interband cascade electroluminescence up to room temperature in a broad mid-infrared wavelength region (extended to 9 {mu}m).

  8. Experimental investigation of gas turbine airfoil aerodynamic performance without and with film cooling in an annular sector cascade

    Energy Technology Data Exchange (ETDEWEB)

    Wiers, S.H.

    2002-02-01

    The steady growing of industrialization, the densification of the anthroposphere, the increasing concern over the effects of gas turbine cruise emissions on the atmosphere threaten the growth of air transportation, and the perception about the possible climatic impact of CO{sub 2} emissions causes a public distinctive sense of responsibility. The conventional energy production techniques, which are based on fossil fuel, will keep its central importance within the global energy production. Forecasts about the increasing air transportation give duplication in the next 10-15 years. The optimization of the specific fuel consumption is necessary to decrease the running costs and the pollution emissions in the atmosphere, which makes an increased process efficiency of stationary turbines as well as of jet engines essential. This leads to the necessity of an increased thermodynamic efficiency of the overall process and the optimization of the aerodynamic components. Due to the necessity of more detailed three-dimensional data on the behavior of film cooled blades an annular sector cascade turbine test facility has gone into service. The annular sector cascade facility is a relative cost efficient solution compared to a full annular facility to investigate three-dimensional effects on a non cooled and cooled turbine blade. The aerodynamic investigations on the annular sector cascade facility are part of a broad perspective where experimental data from a hot annular sector cascade facility and the cold annular sector facility are used to verify, calibrate and understand the physics for both internal and external calculation methods for flow and heat transfer prediction. The objective of the present study is the design and validation of a cold flow annular sector cascade facility, which meets the flow conditions in a modem turbine as close as possible, with emphasis on achieving periodic flow conditions. The first part of this study gives the necessary background on this

  9. Atmospheric and accelerator neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yoichiro [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo Higashi-Mozumi, Kamioka, Hida-City, Gifu 506-1205 (Japan)

    2006-05-15

    Results from the atmospheric neutrino measurements are presented. Evidence for the {nu}{sub {tau}} appearance in the atmospheric neutrino events was shown by statistical methods. The long baseline oscillation experiment using man-made neutrinos has confirmed the atmospheric neutrino oscillation. The future accelerator experiments are briefly discussed.

  10. Atmospheric refraction : a history

    NARCIS (Netherlands)

    Lehn, WH; van der Werf, S

    2005-01-01

    We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of un

  11. Assessment on tracking error performance of Cascade P/PI, NPID and N-Cascade controller for precise positioning of xy table ballscrew drive system

    Science.gov (United States)

    Abdullah, L.; Jamaludin, Z.; Rafan, N. A.; Jamaludin, J.; Chiew, T. H.

    2013-12-01

    At present, positioning plants in machine tools are looking for high degree of accuracy and robustness attributes for the purpose of compensating various disturbance forces. The objective of this paper is to assess the tracking performance of Cascade P/PI, Nonlinear PID (NPID) and Nonlinear cascade (N-Cascade) controller with the existence of disturbance forces in the form of cutting forces. Cutting force characteristics at different cutting parameters; such as spindle speed rotations is analysed using Fast Fourier Transform. The tracking performance of a Nonlinear cascade controller in presence of these cutting forces is compared with NPID controller and Cascade P/PI controller. Robustness of these controllers in compensating different cutting characteristics is compared based on reduction in the amplitudes of cutting force harmonics using Fast Fourier Transform. It is found that the N-cascade controller performs better than both NPID controller and Cascade P/PI controller. The average percentage error reduction between N-cascade controller and Cascade P/PI controller is about 65% whereas the average percentage error reduction between cascade controller and NPID controller is about 82% at spindle speed of 3000 rpm spindle speed rotation. The finalized design of N-cascade controller could be utilized further for machining application such as milling process. The implementation of N-cascade in machine tools applications will increase the quality of the end product and the productivity in industry by saving the machining time. It is suggested that the range of the spindle speed could be made wider to accommodate the needs for high speed machining.

  12. Multi-species trace gas analysis with dual-wavelength quantum cascade laser

    Science.gov (United States)

    Jágerská, Jana; Tuzson, Béla; Looser, Herbert; Jouy, Pierre; Hugi, Andreas; Mangold, Markus; Soltic, Patrik; Faist, Jérôme; Emmenegger, Lukas

    2015-04-01

    Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly appealing for a large variety of applications ranging from air quality monitoring, medical breath analysis to industrial process control. However, state-of-the-art distributed-feedback (DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally leads to one-laser-one-compound measurement strategy. Thus, multi-species detection involves several lasers and elaborate beam combining solutions [1]. This makes them bulky, costly, and highly sensitive to optical alignment, which limits their field deployment. In this paper, we explore an alternative measurement concept based on a dual-wavelength quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct wavelengths using a succession of two DFB gratings with different periodicities and a common waveguide to produce one output beam. The laser design was optimized for NOx measurements and correspondingly emits single-mode at 5.26 and 6.25 μm. Electrical separation of the respective laser sections makes it possible to address each wavelength independently. Thereby, it is possible to detect NO and NO2 species with one laser using the same optical path, without any beam combining optics, i.e. in a compact and cost-efficient single-path optical setup. Operated in a time-division multiplexed mode, the spectrometer reaches detection limits at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system was validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as monitoring the pollution at a suburban site. [1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, and L. Emmenegger, 'Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy,' Atmospheric Measurement Techniques 6, 927-936 (2013

  13. Neutron Transport Associated with the Galactic Cosmic Ray Cascade

    Science.gov (United States)

    Singleterry, Robert Clay, Jr.

    Transport of low energy neutrons associated with the galactic cosmic ray cascade is analyzed in this dissertation. A benchmark quality analytical algorithm is demonstrated for use with B scRYNTRN, a computer program written by the High Energy Physics Division of N scASA Langley Research Center, which is used to design and analyze shielding against the radiation created by the cascade. B scRYNTRN uses numerical methods to solve the integral transport equations for baryons with the straight-ahead approximation, and numerical and empirical methods to generate the interaction probabilities. The straight-ahead approximation is adequate for charged particles, but not for neutrons. As N scASA Langley improves B scRYNTRN to include low energy neutrons, a benchmark quality solution is needed for comparison. The neutron transport algorithm demonstrated in this dissertation uses the closed-form Green's function solution to the galactic cosmic ray cascade transport equations to generate a source of neutrons. A basis function expansion for finite heterogeneous and semi-infinite homogeneous slabs with multiple energy groups and isotropic scattering is used to generate neutron fluxes resulting from the cascade. This method, called the F_{rm N} method, is used to solve the neutral particle linear Boltzmann transport equation. As a demonstration of the algorithm coded in the programs M scGSLAB and M scGSEMI, neutron and ion fluxes are shown for a beam of fluorine ions at 1000 MeV per nucleon incident on semi-infinite and finite aluminum slabs. Also, to demonstrate that the shielding effectiveness against the radiation from the galactic cosmic ray cascade is not directly proportional to shield thickness, a graph of transmitted total neutron scalar flux versus slab thickness is shown. A simple model based on the nuclear liquid drop assumption is used to generate cross sections for the galactic cosmic ray cascade. The E scNDF/B V database is used to generate the total and scattering

  14. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    Science.gov (United States)

    Yates, Jack S.; Palmer, Paul I.; Biller, Beth; Cockell, Charles S.

    2017-02-01

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μm spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 109 cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

  15. Development of a Quantum Cascade Laser-Based Detector for Ammonia and Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Zahniser, Mark S.; Nelson, David D.; McManus, J. Barry; Shorter, Joanne H.; Herndon, Scott C.; Jimenez, Rodrigo

    2005-12-31

    We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

  16. Theoretical comparison of subgrid turbulence in the atmosphere and ocean

    Directory of Open Access Journals (Sweden)

    V. Kitsios

    2015-12-01

    Full Text Available Due to the massive disparity between the largest and smallest eddies in the atmosphere and ocean, it is not possible to simulate these flows by explicitly resolving all scales on a computational grid. Instead the large scales are explicitly resolved, and the interactions between the unresolved subgrid turbulence and large resolved scales are parameterised. If these interactions are not properly represented then an increase in resolution will not necessarily improve the accuracy of the large scales. This has been a significant and long standing problem since the earliest climate simulations. Historically subgrid models for the atmosphere and ocean have been developed in isolation, with the structure of each motivated by different physical phenomena. Here we solve the turbulence closure problem by determining the parameterisation coefficients (eddy viscosities from the subgrid statistics of high resolution quasi-geostrophic atmospheric and oceanic simulations. These subgrid coefficients are characterised into a set of simple unifying scaling laws, for truncations made within the enstrophy cascading inertial range. The ocean additionally has an inverse energy cascading range, within which the subgrid model coefficients have alternative scaling properties. Simulations adopting these scaling laws are shown to reproduce the statistics of the reference benchmark simulations across resolved scales, with orders of magnitude improvement in computational efficiency. This reduction in both resolution dependence and computational effort will improve the efficiency and accuracy of geophysical research and operational activities that require data generated by general circulation models, including: weather, seasonal and climate prediction; transport studies; and understanding natural variability and extreme events.

  17. Enhanced Kerr electro-optic nonlinearity through cascaded Pockels effects

    CERN Document Server

    Li, Guang-Zhen; Jiang, Hao-Wei; Chen, Xian-Feng

    2015-01-01

    We demonstrated a large enhancement of Kerr electro-optic nonlinearity through cascaded Pockels effects in a domain inversion ferroelectric crystal. We designed a structure that can implement the cascaded Pockels effects and second-harmonic generation simultaneously. The energy coupling between the fundamental lights of different polarizations led to a large nonlinear phase shift, and thus an effective electro-optic nonlinear refractive index. The effective nonlinearity can be either positive or negative, causing the second-harmonic spectra to move towards the coupling center, which in turn, offered us a way to measure the effective electro-optic nonlinear refractive index. The corresponding enhanced Kerr electro-optic nonlinearity is more than three orders of magnitude higher than the intrinsic value. These results open a door to manipulate the nonlinear phase by applying external electric field instead of light intensity in noncentrosymmetric crystals.

  18. Optimized multibeam configuration for observation of QED cascades

    CERN Document Server

    Gelfer, E G; Fedotov, A M; Bashmakov, V F; Nerush, E N; Kostyukov, I Y; Narozhny, N B

    2015-01-01

    QED cascades in intense electromagnetic field can occur if the dynamical quantum parameter $\\chi$ of a seed electron, which in Compton units coincides with the electron proper acceleration, attains the order of unity. We derive general expression for $\\chi$ of an initially slow electron in an arbitrary electromagnetic field for a time range $t\\ll 1/\\omega$, where $\\omega$ is the field carrier frequency. Using this formula, we consider a special field configuration of multiple colliding focused laser beams and optimize it to provide cascade development at laser power below $10$ PW and intensity of the order of $10^{23}$W/cm$^2$. Such parameters of the beams will be obtained with a new generation of laser facilities, particularly the ELI Beamlines, in the coming years.

  19. EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TURBULENT AIR-CUSHION-CASCADE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Experimental and numerical studies of air-cushion-cascade were conducted and described. The SIMPLE algorithm combined with the normal k-ε turbulence model was adopted to simulate the air-phase flow. The experiment was carried out an IFA 300 anemometer. The flow field was measured for different ratios of main-stream velocity to jet velocity, different numbers of gaps and a couple of gap widths. The contur of the air-cushion was obtained, and the numerical calculations gave a closed-form result. The results show that the air-cushion thickness would increase with the increase of the jet volcoity, gap width and gap number mainly determined by the jet in the former half cascade. The possibility to achieve anti-erosion by the turbulent jet was examined and confirmed.

  20. Influence of the material parameters on quantum cascade devices

    Science.gov (United States)

    Benveniste, E.; Vasanelli, A.; Delteil, A.; Devenson, J.; Teissier, R.; Baranov, A.; Andrews, A. M.; Strasser, G.; Sagnes, I.; Sirtori, C.

    2008-09-01

    An experimental investigation on the influence of the material systems on the optical properties of quantum cascade structures is presented. Three electroluminescent quantum cascade devices have been grown using GaAs /AlGaAs, GaInAs /AlInAs, and InAs /AlSb heterostructures. The devices emit at 10μm and are based on a similar bandstructure design. Our results verify that the optical quantum efficiency has the predicted dependence on the electron effective mass. We also demonstrate that the shape of the electroluminescence spectra is independent from the particular material parameters and mainly depends on the tunnel coupling between the injector state and the upper state of the radiative transition.

  1. Emergence of a Turbulent Cascade in a Quantum Gas

    CERN Document Server

    Navon, Nir; Smith, Robert P; Hadzibabic, Zoran

    2016-01-01

    In the modern understanding of turbulence, a central concept is the existence of cascades of excitations from large to small lengthscales, or vice-versa. This concept was introduced in 1941 by Kolmogorov and Obukhov, and the phenomenon has since been observed in a variety of systems, including interplanetary plasmas, supernovae, ocean waves, and financial markets. Despite a lot of progress, quantitative understanding of turbulence remains a challenge due to the interplay of many lengthscales that usually thwarts theoretical simulations of realistic experimental conditions. Here we observe the emergence of a turbulent cascade in a weakly interacting homogeneous Bose gas, a quantum fluid that is amenable to a theoretical description on all relevant lengthscales. We prepare a Bose-Einstein condensate (BEC) in an optical box, drive it out of equilibrium with an oscillating force that pumps energy into the system at the largest lengthscale, study the BEC's nonlinear response to the periodic drive, and observe a gr...

  2. Cascaded forward Brillouin scattering to all Stokes orders

    CERN Document Server

    Wolff, Christian; Eggleton, Benjamin J; Steel, Michael J; Poulton, Christopher G

    2016-01-01

    Inelastic scattering processes such as Brillouin scattering can often function in cascaded regimes and this is likely to occur in certain integrated opto-acoustic devices. We develop a Hamiltonian formalism for cascaded Brillouin scattering valid for both quantum and classical regimes. By regarding Brillouin scattering as the interaction of a single acoustic envelope and a single optical envelope that covers all Stokes and anti-Stokes orders, we obtain a compact model that is well suited for numerical implementation, extension to include other optical nonlinearities or short pulses, and application in the quantum-optics domain. We then theoretically analyze intra-mode forward Brillouin scattering (FBS) for arbitrary waveguides with and without optical dispersion. In the absence of optical dispersion, we find an exact analytical solution. With a perturbative approach, we furthermore solve the case of weak optical dispersion. Our work leads to several key results on intra-mode FBS. For negligible dispersion, we...

  3. Zone 3 Relay Blocking Scheme to Prevent Cascaded Events

    Institute of Scientific and Technical Information of China (English)

    LIM Seong-Il

    2008-01-01

    Defense systems are needed to prevent catastrophic failures of a power grid due to cas- caded events. Cascaded events can be attributed to improper operations of protective relays. The most challenging problem for the design and implementation of a defense system is the perform- ance in accuracy and speed in a real time environment. Protective devices are normally designed to operate fast in order to isolate the fault(s). This paper proposes a new methodology to distin- guish line overloads from actual faults for distance relays. In order to distinguish between line flow transfers from a line outage and an actual fault, the line outage distribution factor (LODF) and gen-eration shift factor (GSF) based power flow estimation method, and a secure peer to peer (P2P) communication structure are adopted. Computer simulations of cascaded events for a 6-bus sys- tem and the Korean power grid have been performed to establish the feasibility of the proposed scheme.

  4. Multi Agent System Based Wide Area Protection against Cascading Events

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Liu, Leo;

    2012-01-01

    In this paper, a multi-agent system based wide area protection scheme is proposed in order to prevent long term voltage instability induced cascading events. The distributed relays and controllers work as a device agent which not only executes the normal function automatically but also can...... the effectiveness of proposed protection strategy. The simulation results indicate that the proposed multi agent control system can effectively coordinate the distributed relays and controllers to prevent the long term voltage instability induced cascading events....... be modified to fulfill the extra function according to external requirements. The control center is designed as a highest level agent in MAS to coordinate all the lower agents to prevent the system wide voltage disturbance. A hybrid simulation platform with MATLAB and RTDS is set up to demonstrate...

  5. Cascading failures in congested complex networks with feedback

    Institute of Scientific and Technical Information of China (English)

    Zheng Jian-Feng; Gao Zi-You; Fu Sai-Bai; Li Feng

    2009-01-01

    In this article, we investigate cascading failures in complex networks by introducing a feedback. To characterize the effect of the feedback, we define a procedure that involves a self-organization of trip distribution during the process of cascading failures. For this purpose, user equilibrium with variable demand is used as an alternative way to determine the traffic flow pattern throughout the network. Under the attack, cost function dynamics are introduced to discuss edge overload in complex networks, where each edge is assigned a finite capacity (controlled by parameter α). We find that scale-free networks without considering the effect of the feedback are expected to be very sensitive to a as compared with random networks, while this situation is largely improved after introducing the feedback.

  6. Molecular dynamics simulation of radiation damage cascades in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Buchan, J. T. [Department of Physics and Astronomy, Curtin University, Perth, Western Australia 6845 (Australia); Robinson, M. [Nanochemistry Research Institute, Curtin University, Perth, Western Australia 6845 (Australia); Christie, H. J.; Roach, D. L.; Ross, D. K. [Physics and Materials Research Centre, School of Computing, Science and Engineering, University of Salford, Salford, Greater Manchester M5 4WT (United Kingdom); Marks, N. A. [Department of Physics and Astronomy, Curtin University, Perth, Western Australia 6845 (Australia); Nanochemistry Research Institute, Curtin University, Perth, Western Australia 6845 (Australia)

    2015-06-28

    Radiation damage cascades in diamond are studied by molecular dynamics simulations employing the Environment Dependent Interaction Potential for carbon. Primary knock-on atom (PKA) energies up to 2.5 keV are considered and a uniformly distributed set of 25 initial PKA directions provide robust statistics. The simulations reveal the atomistic origins of radiation-resistance in diamond and provide a comprehensive computational analysis of cascade evolution and dynamics. As for the case of graphite, the atomic trajectories are found to have a fractal-like character, thermal spikes are absent and only isolated point defects are generated. Quantitative analysis shows that the instantaneous maximum kinetic energy decays exponentially with time, and that the timescale of the ballistic phase has a power-law dependence on PKA energy. Defect recombination is efficient and independent of PKA energy, with only 50% of displacements resulting in defects, superior to graphite where the same quantity is nearly 75%.

  7. Magnetohydrodynamic turbulent cascade of coronal loop magnetic fields.

    Science.gov (United States)

    Rappazzo, A F; Velli, M

    2011-06-01

    The Parker model for coronal heating is investigated through a high resolution simulation. An inertial range is resolved where fluctuating magnetic energy EMk[Please see symbol]) [Please see symbol] k[Please see symbol](-2.7) exceeds kinetic energy EK(k[Please see symbol])[Please see symbol]k[Please see symbol](-0.6). Increments scale as δbℓ ~/= ℓ(-0.85) and δuℓ ~/= ℓ(+0.2) with velocity increasing at small scales, indicating that magnetic reconnection plays a prime role in this turbulent system. We show that spectral energy transport is akin to standard magnetohydrodynamic (MHD) turbulence even for a system of reconnecting current sheets sustained by the boundary. In this new MHD turbulent cascade, kinetic energy flows are negligible while cross-field flows are enhanced, and through a series of "reflections" between the two fields, cascade more than half of the total spectral energy flow.

  8. Delay time calculation for dual-wavelength quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hamadou, A., E-mail: abd-hamado@yahoo.fr [Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université de Bordj Bou Arreridj 34000 (Algeria); Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Lamari, S. [Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 (Algeria); Thobel, J.-L. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR 8520, Université Lille1, Avenue Poincaré, BP 60069, 59652 Villeneuve d' Ascq Cédex (France)

    2013-11-28

    In this paper, we calculate the turn-on delay (t{sub th}) and buildup (Δt) times of a midinfrared quantum cascade laser operating simultaneously on two laser lines having a common upper level. The approach is based on the four-level rate equations model describing the variation of the electron number in the states and the photon number present within the cavity. We obtain simple analytical formulae for the turn-on delay and buildup times that determine the delay times and numerically apply our results to both the single and bimode states of a quantum cascade laser, in addition the effects of current injection on t{sub th} and Δt are explored.

  9. Contextual processing of structured data by recursive cascade correlation.

    Science.gov (United States)

    Micheli, Alessio; Sona, Diego; Sperduti, Alessandro

    2004-11-01

    This paper propose a first approach to deal with contextual information in structured domains by recursive neural networks. The proposed model, i.e., contextual recursive cascade correlation (CRCC), a generalization of the recursive cascade correlation (RCC) model, is able to partially remove the causality assumption by exploiting contextual information stored in frozen units. We formally characterize the properties of CRCC showing that it is able to compute contextual transductions and also some causal supersource transductions that RCC cannot compute. Experimental results on controlled sequences and on a real-world task involving chemical structures confirm the computational limitations of RCC, while assessing the efficiency and efficacy of CRCC in dealing both with pure causal and contextual prediction tasks. Moreover, results obtained for the real-world task show the superiority of the proposed approach versus RCC when exploring a task for which it is not known whether the structural causality assumption holds.

  10. InAs based terahertz quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Brandstetter, Martin, E-mail: martin.brandstetter@tuwien.ac.at; Kainz, Martin A.; Krall, Michael; Schönhuber, Sebastian; Unterrainer, Karl [Photonics Institute and Center for Micro- and Nanostructures, Technische Universität Wien, Gusshausstrasse 27-29, 1040 Vienna (Austria); Zederbauer, Tobias; Schrenk, Werner; Andrews, Aaron Maxwell; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Technische Universität Wien, Floragasse 7, 1040 Vienna (Austria); Detz, Hermann [Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Vienna (Austria)

    2016-01-04

    We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs{sub 0.16}Sb{sub 0.84} heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAs or InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonant phonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applying a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.

  11. Energy transfer and dual cascade in kinetic magnetized plasma turbulence.

    Science.gov (United States)

    Plunk, G G; Tatsuno, T

    2011-04-22

    The question of how nonlinear interactions redistribute the energy of fluctuations across available degrees of freedom is of fundamental importance in the study of turbulence and transport in magnetized weakly collisional plasmas, ranging from space settings to fusion devices. In this Letter, we present a theory for the dual cascade found in such plasmas, which predicts a range of new behavior that distinguishes this cascade from that of neutral fluid turbulence. These phenomena are explained in terms of the constrained nature of spectral transfer in nonlinear gyrokinetics. Accompanying this theory are the first observations of these phenomena, obtained via direct numerical simulations using the gyrokinetic code AstroGK. The basic mechanisms that are found provide a framework for understanding the turbulent energy transfer that couples scales both locally and nonlocally.

  12. Statistical Classification of Cascading Failures in Power Grids

    CERN Document Server

    Pfitzner, René; Chertkov, Michael

    2010-01-01

    We introduce a new microscopic model of the outages in transmission power grids. This model accounts for the automatic response of the grid to load fluctuations that take place on the scale of minutes, when the optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, initiated by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systems consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascadi...

  13. Laser absorption via QED cascades in counter propagating laser pulses

    CERN Document Server

    Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo A; Silva, Luis O

    2015-01-01

    A model for laser light absorption in electron-positron plasmas self-consistently created via QED cascades is described. The laser energy is mainly absorbed due to hard photon emission via nonlinear Compton scattering. The degree of absorption depends on the laser intensity and the pulse duration. The QED cascades are studied with multi-dimensional particle-in-cell simulations complemented by a QED module and a macro-particle merging algorithm that allows to handle the exponential growth of the number of particles. Results range from moderate-intensity regimes ($\\sim$ 10 PW) where the laser absorption is negligible, to extreme intensities (> 100 PW) where the degree of absorption reaches 80%. Our study demonstrates good agreement between the analytical model and simulations. The expected properties of the hard photon emission and the generated pair-plasma are investigated, and the experimental signatures for near-future laser facilities are discussed.

  14. A Theory of Unstaggered Airfoil Cascades in Compressible Flow

    Science.gov (United States)

    Spurr, Robert A.; Allen, H. Julian

    1947-01-01

    By use of the methods of thin airfoil theory, which include effects of compressibility, rela.tio^as are developed which permit the rapid determination of the pressure distribution over an unstaggered cascade of airfoils of a given profile, and the determination of the profile shape necessary to yield a given pressure distribution for small chord gap ratios, For incompressible flow the results of the theory are compared with available examples obtained by the more exact method of conformal transformation. Although the theory is developed for small chord/gap ratios, these comparisons show that it may be extended to chord/gap ratios of order unity, at least for low speed flows. Choking of cascades, a phenomenon of particular importance in compressor design, is considered.

  15. Cascade Apartments - Deep Energy Multifamily Retrofit , Kent, Washington (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  16. Rapid cascade condition assessment of ductwork via robot vision

    Science.gov (United States)

    Wang, Yongxiong; Su, Jianbo

    2012-02-01

    Automatic assessment of condition in ductwork is very desirable in applications. Presented is a visual condition diagnosis approach, which is capable of processing images rapidly and achieving high accuracy rates. A hierarchical coarse-to-fine image segmentation method is employed. False alarms could thus be progressively eliminated, which is robust in strongly noisy conditions. The simple classifiers combined in a cascade quickly classify the detected images and discard the uninterested (non-object) images, leaving more computation power on promising object-like regions. The features of each simple classifier are selected based on the Bhattacharyya distance. The cascade can be viewed as an object-specific focus-of-attention mechanism. Experimental results validate the effectiveness and rapidity of the proposed assessment method.

  17. PULSE MODULATION POWER AMPLIFIER WITH ENHANCED CASCADE CONTROL METHOD

    DEFF Research Database (Denmark)

    1998-01-01

    A digital switching power amplifier with Multivariable Enhanced Cascade Controlled (MECC) includes a modulator, a switching power stage and a low pass filter. In the first preferred embodiment an enhanced cascade control structure local to the switching power stage is added, characterised by having...... a single local feedback path A (7) with a lowpass characteristic and local forward blocks B¿1? or B (3, 4). The leads to a much improved system with a very low sensitivity to errors in the switching power stage. In the second preferred embodiment of the invention the control structure is extended...... by adding/removing simple local (3) or global (1) forward path blocks. A third embodiment of the invention is a controlled self-oscillating pulse modulator, characterised by first a non-hysteresis comparator as modulator and second by a higher order oscillating loop realised in both forward path B1...

  18. Forward design of a complex enzyme cascade reaction

    Science.gov (United States)

    Hold, Christoph; Billerbeck, Sonja; Panke, Sven

    2016-01-01

    Enzymatic reaction networks are unique in that one can operate a large number of reactions under the same set of conditions concomitantly in one pot, but the nonlinear kinetics of the enzymes and the resulting system complexity have so far defeated rational design processes for the construction of such complex cascade reactions. Here we demonstrate the forward design of an in vitro 10-membered system using enzymes from highly regulated biological processes such as glycolysis. For this, we adapt the characterization of the biochemical system to the needs of classical engineering systems theory: we combine online mass spectrometry and continuous system operation to apply standard system theory input functions and to use the detailed dynamic system responses to parameterize a model of sufficient quality for forward design. This allows the facile optimization of a 10-enzyme cascade reaction for fine chemical production purposes. PMID:27677244

  19. Heavy Flavour Cascade Production in a Beam Dump

    CERN Document Server

    2015-01-01

    SHiP will use a 400~GeV/c proton beam impinging on a several interaction length long Molybdenum target. Heavy flavour hadrons produced in the dump can decay semi-leptonically, which can produce both the Heavy Neutral Leptons as signal, but also potential background from muons and neutrinos. The absolute rate of heavy flavour production is taken from measurements. Pythia is used to predict the phase space distribution of the charm and beauty hadrons which are produced both in the primary interaction of the 400~GeV/c proton and in interactions of the secondaries produced in the cascade. The full cascade production of both HNL and background is compared to that reported in the SHiP Technical Proposal, where only the primary $pN$ interactions were taken into account.

  20. Ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation.

    Science.gov (United States)

    Guo, Changlei; Che, Kaijun; Cai, Zhiping; Liu, Shuai; Gu, Guoqiang; Chu, Chengxu; Zhang, Pan; Fu, Hongyan; Luo, Zhengqian; Xu, Huiying

    2015-11-01

    We experimentally demonstrate an ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation in a high-Q silica microsphere resonator. The threshold of the Brillouin microlaser is as low as 8 μW, which is close to the theoretical prediction. Moreover, the fifth-order Stokes line with a frequency shift up to 55 GHz is achieved with a coupled pump power of less than 0.6 mW. Benefiting from resonant wavelength shifts driven by thermal dynamics in the microsphere, we further realized tunable microwave signals with tuning ranges of 40 MHz at an 11 GHz band and 20 MHz at a 22 GHz band. To the best of our knowledge, it was the first attempt for tunable microwave source based on the whispering-gallery-mode Brillouin microlaser. Such a tunable microwave source from a cascaded Brillouin microlaser could find significant applications in aerospace, communication engineering, and metrology.

  1. Predictions via large {theta}{sub 13} from cascades

    Energy Technology Data Exchange (ETDEWEB)

    Haba, Naoyuki, E-mail: haba@phys.sci.osaka-u.ac.jp [Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Takahashi, Ryo, E-mail: ryo.takahashi@mpi-hd.mpg.de [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

    2011-08-26

    We investigate a relation among neutrino observables, three mixing angles and two mass squared differences, from a cascade texture of neutrino mass matrix. We show an allowed region of the correlation by use of current data of neutrino oscillation experiments. The relation predicts sharp correlations among neutrino mixing angles as 0.315{<=}sin{sup 2}{theta}{sub 12}{<=}0.332 and 0.480{<=}sin{sup 2}{theta}{sub 23}{<=}0.500 with a large {theta}{sub 13} (0.03cascade form.

  2. Damage production in atomic displacement cascades in beryllium

    Directory of Open Access Journals (Sweden)

    V.A. Borodin

    2016-12-01

    Full Text Available The paper presents the results of a molecular dynamics simulation of cascade damage production in beryllium caused by self-ion recoils in the energy range of 0.5–3keV. It is demonstrated that point defects are produced in Be preferentially in well-separated subcascades generated by secondary and higher order recoils. A linear dependence of the point defect number on the primary recoil energy is obtained with the slope that corresponds to formal atom displacement energy of ∼21eV. Most of the damage is created as single defects and the relatively high part of created point defects (∼50% survives the correlated recombination following the ballistic cascade stage and becomes freely-migrating.

  3. Cascade Protector for Hardening Electronic Devices against High Power Microwaves

    Directory of Open Access Journals (Sweden)

    Geng Yang

    2009-01-01

    Full Text Available Since the increasing front part of incident microwave pulses may pass through plasma limiter before it generates plasma (the breakdown time of low pressure Xe in plasma limiter is 10 ns, single plasma limiters are not adequate for protecting sensitive electronic components against high power microwaves (HPM. A cascade protector, which consists of a plasma limiter and a PIN limiter in waveguide, is proposed. The numerical results show that under HPM attack (10 GW, 1GHz, and 100 ns pulse width, the microwave power leakage through the cascade protector is about 0.4 W. In the same electromagnetic environment, the power leakage through single plasma limiter is approximate 347 W.Defence Science Journal, 2009, 59(1, pp.55-57, DOI:http://dx.doi.org/10.14429/dsj.59.1485

  4. Cascading Power Outages Propagate Locally in an Influence Graph that is not the Actual Grid Topology

    CERN Document Server

    Hines, Paul D H; Rezaei, Pooya

    2015-01-01

    In a cascading power transmission outage, component outages propagate non-locally; after one component outages, the next failure may be very distant, both topologically and geographically. As a result, simple models of topological contagion do not accurately represent the propagation of cascades in power systems. However, cascading power outages do follow patterns, some of which are useful in understanding and reducing blackout risk. This paper describes a method by which the data from many cascading failure simulations can be transformed into a graph-based model of influences that provides actionable information about the many ways that cascades propagate in a particular system. The resulting "influence graph" model is Markovian, since component outage probabilities depend only on the outages that occurred in the prior generation. To validate the model we compare the distribution of cascade sizes resulting from n-2 contingencies in a 2896 branch test case to cascade sizes in the influence graph. The two dist...

  5. The effects of self-interstitial clusters on cascade defect evolution beyond the primary damage state

    Energy Technology Data Exchange (ETDEWEB)

    Heinisch, H.L. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-04-01

    The intracascade evolution of the defect distributions of cascades in copper is investigated using stochastic annealing simulations applied to cascades generated with molecular dynamics (MD). The temperature and energy dependencies of annihilation, clustering and free defect production are determined for individual cascades. The annealing simulation results illustrate the strong influence on intracascade evolution of the defect configuration existing in the primary damage state. Another factor significantly affecting the evolution of the defect distribution is the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. This phenomenon introduces a cascade energy dependence of defect evolution that is apparent only beyond the primary damage state, amplifying the need for further study of the annealing phase of cascade evolution and for performing many more MD cascade simulations at higher energies.

  6. 2-μm switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect

    Science.gov (United States)

    Wang, Shun; Lu, Ping; Zhao, Shui; Liu, Deming; Yang, Wei; Zhang, Jiangshan

    2014-06-01

    We demonstrated a 2-μm switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect. Few-mode fiber-embedded Sagnac ring configuration and a Mach-Zehnder interferometer are cascaded to form a multiwavelength filter for our previous 2-μm fiber laser. By adopting suitable fiber length and adjusting the polarization controller, we obtained a 2-μm dual-wavelength fiber laser with switchable wavelength interval. Experimental results revealed that the proposed laser shows higher quality and better stability compared with our previous work and it has potential applications in the fields of atmospheric propagation and microwave photonics.

  7. A New Phase-Shifted Cascade High Voltage Inverter

    Institute of Scientific and Technical Information of China (English)

    Lau Eng Tin

    2005-01-01

    This paper presents a unique novel design of the phase-shifted cascade high voltage inverter. Thehigh voltage inverter utilizes fewer power switches and supplies a balance load. The usage of phase shifttransformer and phase shifting SPWM ensures that input and output harmonic wave content is low and outputvoltage change (du/dt) has a low rate, meeting all the requirements of the power authorities. The most out-standing feature is the energy saving with very fast cost recovery.

  8. SEWAGE SLUDGE COMBUSTION IN A SPOUTED BED CASCADE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Mirko Barz

    2003-01-01

    @@ In modern society, sewage is disposed of in a two-step process: it is first made into granules and the sewage sludge granules are then burned in an appropriate combustor. The present paper describes a spouted bed cascade system for sewage sludge combustion developed at the Technical University of Berlin at the turn of the present century. Combustion results in the recovery of the combustible matters of the sewage in the form of thermal energy.

  9. Involvement of the MAP kinase cascade in Xenopus mesoderm induction.

    OpenAIRE

    Gotoh, Y.; Masuyama, N; Suzuki, A.; Ueno, N; Nishida, E

    1995-01-01

    Mitogen-activated protein kinase (MAPK) is activated by MAPK kinase (MAPKK) in a variety of signaling pathways. This kinase cascade has been shown to function in cell proliferation and differentiation, but its role in early vertebrate development remains to be investigated. During early vertebrate embryogenesis, the induction and patterning of mesoderm are thought to be determined by signals from intercellular factors such as members of the fibroblast growth factor (FGF) family and members of...

  10. Network Adaptability from WMD Disruption and Cascading Failures

    Science.gov (United States)

    2016-04-01

    on the electric grid (or technical problems in a power plant). In this case, some of the network resources will consume electricity from generators...backbone networks due to several reasons among which the primary being the popularity of cloud services, smart devices, video applications, etc. On top of... Network Adaptability from WMD Disruption and Cascading Failures Distribution Statement A. Approved for public release; distribution is unlimited

  11. Unconditional preparation of entanglement between atoms in cascaded optical cavities.

    Science.gov (United States)

    Clark, Stephen; Peng, Amy; Gu, Mile; Parkins, Scott

    2003-10-24

    We propose a scheme to unconditionally entangle the internal states of atoms trapped in separate high-finesse optical cavities. The scheme uses the technique of quantum reservoir engineering in a cascaded cavity-QED setting, and for ideal (lossless) coupling between the cavities generates an entangled pure state. Highly entangled states are also shown to be possible for realizable cavity-QED parameters and with nonideal coupling.

  12. Research on Cascade Double Г-CL Resonant Inverter

    Institute of Scientific and Technical Information of China (English)

    ZhuJianhua; LuoFanglin

    2004-01-01

    A cascade double Г-CL current source resonant inverter (CSRI) is proposed in this paper, which overcomes the limitations of the conventional two or three energy-storage elements resonant inverters. Comparing with the counterparts, the novel inverter has larger current transfer gain with smooth waveforms. The simulation process is manipulated on the basis of the state-space averaging approach. The power transfer efficiency is studied in detail. Finally. the theoretical analysis is verified with the simulative and testing results.

  13. Efficient method for transport simulations in quantum cascade lasers

    Directory of Open Access Journals (Sweden)

    Maczka Mariusz

    2017-01-01

    Full Text Available An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green’s functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  14. Efficient method for transport simulations in quantum cascade lasers

    Science.gov (United States)

    Maczka, Mariusz; Pawlowski, Stanislaw

    2016-12-01

    An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green's functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  15. Terahertz Quantum-Cascade Transmission-Line Metamaterials

    OpenAIRE

    Tavallaee, Amir Ali

    2012-01-01

    Terahertz quantum-cascade (QC) lasers operating at 0.6 − 5 THz (λ ∼ 60 − 500 μm) are poised to become the dominant solid-state sources of continuous-wave (cw) far-infrared radiation enabling applications in terahertz spectroscopy, imaging, and sensing. QC-lasers are the longest wavelength semiconductor laser sources in which terahertz gain is obtained from electronic intersubband radiative transitions in GaAs/AlGaAs heterostructure quantum wells. Since their invent...

  16. Cascade upgrading of γ-valerolactone to biofuels.

    Science.gov (United States)

    Yan, Kai; Lafleur, Todd; Wu, Xu; Chai, Jiajue; Wu, Guosheng; Xie, Xianmei

    2015-04-25

    Cascade upgrading of γ-valerolactone (GVL), produced from renewable cellulosic biomass, with selective conversion to biofuels pentyl valerate (PV) and pentane in one pot using a bifunctional Pd/HY catalyst is described. Excellent catalytic performance (over 99% conversion of GVL, 60.6% yield of PV and 22.9% yield of pentane) was achieved in one step. These biofuels can be targeted for gasoline and jet fuel applications.

  17. Trophically Unique Species Are Vulnerable to Cascading Extinction

    OpenAIRE

    Petchey, Owen L.; Eklöf, Anna; Borrvall, Charlotte; Ebenman, Bo

    2008-01-01

    Understanding which species might become extinct and the consequences of such loss is critical. One consequence is a cascade of further, secondary extinctions. While a significant amount is known about the types of communities and species that suffer secondary extinctions, little is known about the consequences of secondary extinctions for biodiversity. Here we examine the effect of these secondary extinctions on trophic diversity, the range of trophic roles played by the species in a communi...

  18. PLAIN CASCADE RESEARCH ON A REVERSIBLE COMBINED BLADE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventilation. The optimal parameters such as overlap ratio and pitch ratio are determined through cascade experiment. Experiment results also show a big promotion of maximum lift coefficient Cl,max and stall attack angle (l,max compared to the existing bi-directional symmetry airfoils.

  19. Analysis of extrapolation cascadic multigrid method(EXCMG)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on an asymptotic expansion of finite element,a new extrapolation formula and extrapolation cascadic multigrid method(EXCMG)are proposed,in which the new extrapolation and quadratic interpolation are used to provide a better initial value on refined grid.In the case of triple grids,the error of the new initial value is analyzed in detail.A larger scale computation is completed in PC.

  20. Synchronization analysis on cascaded multilevel converters with distributed control

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cascaded multilevel converters built with integrated modules have many advantages such as increased power density,flexible distributed control, multi-functionality, increased reliability and short design cycles. However, the system performance will be affected due to the synchronization errors among each integrated modules. This paper analyzes the impact of the three kinds of synchronization errors on the whole system performance, as well as detailed synchronization implementation. Some valuable conclusions are derived from the theoretical analysis, simulations and experimental results.

  1. Null controllability of a cascade system of Schrodinger equations

    Directory of Open Access Journals (Sweden)

    Marcos Lopez-Garcia

    2016-03-01

    Full Text Available This article presents a control problem for a cascade system of two linear N-dimensional Schrodinger equations. We address the problem of null controllability by means of a control supported in a region not satisfying the classical geometrical control condition. The proof is based on the application of a Carleman estimate with degenerate weights to each one of the equations and a careful analysis of the system in order to prove null controllability with only one control force.

  2. Unconditional preparation of entanglement between atoms in cascaded optical cavities

    CERN Document Server

    Clark, S; Gu, M; Parkins, S; Clark, Stephen; Peng, Amy; Gu, Mile; Parkins, Scott

    2003-01-01

    We propose a scheme to unconditionally entangle the internal states of atoms trapped in separate high finesse optical cavities. The scheme uses the technique of quantum reservoir engineering in a cascaded cavity QED setting, and for ideal (lossless) coupling between the cavities generates an entangled pure state. Highly entangled states are also shown to be possible for realizable cavity QED parameters and with nonideal coupling.

  3. Aerodynamic Performance and Turbulence Measurements in a Turbine Vane Cascade

    Science.gov (United States)

    Boyle, Robert J.; Lucci, Barbara L.; Senyitko, Richard G.

    2002-01-01

    Turbine vane aerodynamics were measured in a three vane linear cascade. Surface pressures and blade row losses were obtained over a range of Reynolds and Mach number for three levels of turbulence. Comparisons are made with predictions using a quasi-3D Navier-Stokes analysis. Turbulence intensity measurement were made upstream and downstream of the vane. The purpose of the downstream measurements was to determine how the turbulence was affected by the strong contraction through 75 deg turning.

  4. Cascaded VLSI neural network architecture for on-line learning

    Science.gov (United States)

    Duong, Tuan A. (Inventor); Daud, Taher (Inventor); Thakoor, Anilkumar P. (Inventor)

    1995-01-01

    High-speed, analog, fully-parallel and asynchronous building blocks are cascaded for larger sizes and enhanced resolution. A hardware-compatible algorithm permits hardware-in-the-loop learning despite limited weight resolution. A comparison-intensive feature classification application has been demonstrated with this flexible hardware and new algorithm at high speed. This result indicates that these building block chips can be embedded as application-specific-coprocessors for solving real-world problems at extremely high data rates.

  5. Fibonacci order in the period-doubling cascade to chaos

    Energy Technology Data Exchange (ETDEWEB)

    Linage, G. [Facultad de Ciencias UAEM, Avenida Universidad 1001, Colonia Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Montoya, Fernando [Facultad de Ciencias UAEM, Avenida Universidad 1001, Colonia Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Sarmiento, A. [Instituto de Matematicas, UNAM, Colonia Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Showalter, K. [Department of Chemistry, West Virginia University, Morgantown, WV 26506-6045 (United States); Parmananda, P. [Facultad de Ciencias UAEM, Avenida Universidad 1001, Colonia Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico)]. E-mail: punit@servm.fc.uaem.mx

    2006-12-11

    In this contribution, we describe how the Fibonacci sequence appears within the Feigenbaum scaling of the period-doubling cascade to chaos. An important consequence of this discovery is that the ratio of successive Fibonacci numbers converges to the golden mean in every period-doubling sequence and therefore the convergence to {phi}, the most irrational number, occurs in concert with the onset of deterministic chaos.

  6. Multisensory perception and action in 3-ball cascade juggling

    OpenAIRE

    Sánchez García, Raúl; Hayes, S J; Williams, A M; Bennett, S. J.

    2013-01-01

    Multisensory perception and action in 3-ball cascade juggling was investigated in intermediate-skilled performers by manipulating vision (full or lower field restricted) or ball weight (equal or different). There were main effects for both independent variables but no interactions. Manipulation of ball weight had a more pervasive effect on performance outcome, as well as central tendency and dispersion of kinematic measures of the juggling action. A common finding to both manipulations was th...

  7. EXPERIMENTAL INVESTIGATION OF THE FAILURE OF CASCADE LANDSLIDE DAMS

    Institute of Scientific and Technical Information of China (English)

    NIU Zhi-pan; XU Wei-lin; LI Nai-wen; XUE Yang; CHEN Hua-yong

    2012-01-01

    This paper preseuts results of model tests for the landslide dam failure of a single dam and cascade dams in a sloping channel.The dams were designed to be regular trapezoid with fine sand.A new measuring method named the labeled line locating method was used to digitalize the captured instantaneous pictures.Under two differem inflow discharges,the morphological evolution and the flow patterns during one dam failure and the failure of cascade dams were investigated.The results indicate that when the inflow discharge is large,the deformation pattern of the downstream dam is similar to that of the upstream dam,and both dams are characterized with the overtopping scour throughout the dam failure process.When the inflow discharge is small,the upstream dam is scoured mainly through a sluice slot formed by the longitudinal incision,and the downstream dam is characterized with the overtopping scour.The data set presented in this paper can be used for the validation of numerical models and provide a reference for the flood risk management of cascade landslide dams.

  8. Cascading failures of interdependent modular small-world networks

    Science.gov (United States)

    Zhu, Guowei; Wang, Xianpei; Tian, Meng; Dai, Dangdang; Long, Jiachuan; Zhang, Qilin

    2016-07-01

    Much empirical evidence shows that many real-world networks fall into the broad class of small-world networks and have a modular structure. The modularity has been revealed to have an important effect on cascading failure in isolated networks. However, the corresponding results for interdependent modular small-world networks remain missing. In this paper, we investigate the relationship between cascading failures and the intra-modular rewiring probabilities and inter-modular connections under different coupling preferences, i.e. random coupling with modules (RCWM), assortative coupling in modules (ACIM) and assortative coupling with modules (ACWM). The size of the largest connected component is used to evaluate the robustness from global and local perspectives. Numerical results indicate that increasing intra-modular rewiring probabilities and inter-modular connections can improve the robustness of interdependent modular small-world networks under intra-attacks and inter-attacks. Meanwhile, experiments on three coupling strategies demonstrate that ACIM has a better effect on preventing the cascading failures compared with RCWM and ACWM. These results can be helpful to allocate and optimize the topological structure of interdependent modular small-world networks to improve the robustness of such networks.

  9. Optimization of Dynamic Range of Cascade Filter Realization

    Directory of Open Access Journals (Sweden)

    J. Hospodka

    2006-09-01

    Full Text Available This paper deals with a dynamic range optimization procedure for active filters based on the cascade realization. Dynamic characteristics of the cascade filter depend on many factors, mainly on pole-zero pairing, section ordering and gain assignment. Just the procedure for an optimal gain assignment for particular biquadratic sections is discussed in this paper. The input parameters of the procedure are parameters of particular biquads i.e. pole frequency ω0, quality factor Q, eventually zero frequency ωn for elliptic section and the transfer function type of the section. The gain is distributed so that output signal limitation of particular biquads occurs for the same level of the filter input signal. The procedure is versatile - can be used for analog as well as for digital filters with the cascade structure. The presented algorithm is fully universal (does not suppose any simplification. It has been used in Syntfil package for the filter design in the mathematical program Maple.

  10. CP-violation in cascade decays at the LHC

    CERN Document Server

    Tattersall, Jamie

    We study the potential to observe CP-violating effects in various supersymmetric cascade decay chains at the LHC. Asymmetries composed by triple products of momenta of the final state particles are sensitive to CP-violating effects. We analytically calculate the cascade decays including the relevant spin correlations to compute the parton level asymmetry. In addition, we use Monte Carlo simulations to estimate the sensitivity of the LHC to the CP-violating observables. Due to large boosts that dilute the asymmetries, these can be difficult to observe at the LHC. However, if all particle masses in a cascade decay are known, it may be possible to reconstruct all momenta in the decay chains. We can then recover the full asymmetry on an event-by-event basis even when we have missing momentum due to a stable lightest supersymmetric particle. After the reconstruction, the non-diluted CP-violating signal gets significantly enhanced so that an observation may become feasible. A fully hadronic study has also been co...

  11. THz quantum cascade lasers for standoff molecule detection.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wanke, Michael Clement; Lerttamrab, Maytee; Waldmueller, Ines

    2007-10-01

    Remote optical detection of molecules, agents, and energetic materials has many applications to national security interests. Currently there is significant interest in determining under what circumstances THz frequency coverage will aid in a complete sensing package. Sources of coherent THz frequency (i.e. 0.1 to 10 THz) electromagnetic radiation with requisite power levels, frequency agility, compactness and reliability represent the single greatest obstacle in establishing a THz technology base, but recent advances in semiconductor-based quantum cascade lasers (QCLs) offer huge improvements towards the ultimate THz source goals. This project advanced the development of narrow-linewidth THz quantum cascade lasers. We developed theoretical tools to guide the improvement of standard THz quantum cascade lasers, the investigation of nonlinear optics employing infrared QCLs, and the exploration of quantum coherence to improve QCL performance. The latter was aimed especially towards achieving high temperature operation. In addition we developed a computer algorithm capable of shifting the frequencies of an existing THz QCL to a different frequency and invented a new type of laser that may enable room temperature THz generation in a electrically driven solid-state source.

  12. Process Evaluation Tools for Enzymatic Cascades Welcome Message

    DEFF Research Database (Denmark)

    Abu, Rohana

    Biocatalysis is attracting significant attention from both academic and industrial scientists due to the excellent capability of enzyme to catalyse selective reactions. Recently, much interest has been shown in the application of enzymatic cascades as a useful tool in organic synthesis to synthes......Biocatalysis is attracting significant attention from both academic and industrial scientists due to the excellent capability of enzyme to catalyse selective reactions. Recently, much interest has been shown in the application of enzymatic cascades as a useful tool in organic synthesis...... improvement and implementation. Hence, the goal of this thesis is to evaluate the process concepts in enzymatic cascades in a systematic manner, using tools such as thermodynamic and kinetic analysis. Three relevant case studies have been used to exemplify the approach. In the first case study, thermodynamic...... the equilibrium positions in the main syntheses. In principle, this strategy could successfully achieve high conversion, using ammonia as the sole reagent used in excess to drive the conversion. The findings herein indicate that quantitatively the possibilities for improving the conversion of thermodynamically...

  13. US geothermal database and Oregon cascade thermal studies: (Final report)

    Energy Technology Data Exchange (ETDEWEB)

    Blackwell, D.D.; Steele, J.L.; Carter, L.

    1988-05-01

    This report describes two tasks of different nature. The first of these tasks was the preparation of a data base for heat flow and associated ancillary information for the United States. This data base is being used as the basis for preparation of the United States portion of a geothermal map of North America. The ''Geothermal Map of North America'' will be published as part of the Decade of North American Geology (DNAG) series of the Geological Society of America. The second of these tasks was to make a geothermal evaluation of holes drilled in the Cascade Range as part of a Department of Energy (DOE)/Industry co-sponsored deep drilling project. This second task involved field work, making temperature logs in the holes, and laboratory work, measuring thermal conductivity measurements on an extensive set of samples from these holes. The culmination of this task was an interpretation of heat flow values in terms of the regional thermal conditions; implications for geothermal systems in the Cascade Range; evaluation of the effect of groundwater flow on the depths that need to be drilled for successful measurements in the Cascade Range; and investigation of the nature of the surface groundwater effects on the temperature-depth curves. 40 refs., 7 figs., 7 tabs.

  14. Boolean Models of Biological Processes Explain Cascade-Like Behavior.

    Science.gov (United States)

    Chen, Hao; Wang, Guanyu; Simha, Rahul; Du, Chenghang; Zeng, Chen

    2016-01-29

    Biological networks play a key role in determining biological function and therefore, an understanding of their structure and dynamics is of central interest in systems biology. In Boolean models of such networks, the status of each molecule is either "on" or "off" and along with the molecules interact with each other, their individual status changes from "on" to "off" or vice-versa and the system of molecules in the network collectively go through a sequence of changes in state. This sequence of changes is termed a biological process. In this paper, we examine the common perception that events in biomolecular networks occur sequentially, in a cascade-like manner, and ask whether this is likely to be an inherent property. In further investigations of the budding and fission yeast cell-cycle, we identify two generic dynamical rules. A Boolean system that complies with these rules will automatically have a certain robustness. By considering the biological requirements in robustness and designability, we show that those Boolean dynamical systems, compared to an arbitrary dynamical system, statistically present the characteristics of cascadeness and sequentiality, as observed in the budding and fission yeast cell- cycle. These results suggest that cascade-like behavior might be an intrinsic property of biological processes.

  15. Unraveling high precision stereocontrol in a triple cascade organocatalytic reaction.

    Science.gov (United States)

    Shinisha, C B; Sunoj, Raghavan B

    2008-11-07

    The mechanism and stereoselectivity in an organocatalyzed triple cascade reaction between an aldehyde, electron deficient olefin and an alpha,beta-unsaturated aldehyde are investigated for the first time using density functional theory. The factors responsible for high levels of observed stereoselectivity (Enders et al., Nature, 2006, 441, 861) towards the generation of cyclohexene carbaldehyde with four contiguous stereocentres are unravelled. The triple cascade reaction, comprising a Michael, Michael and aldol sequence as the key elementary reactions, is studied by identifying the corresponding transition states for the stereoselective C-C bond-formation. In the first Michael addition step between the enamine (derived from the chiral catalyst and propanal) and nitrostyrene, energetically the most preferred mode of addition is found to be between the si-face of (E)-anti-enamine on the si-face of nitrostyrene. The addition of the si-face of the nitroalkane anion on the re-face of the iminium ion (formed between the enal and the catalyst) is the lowest energy pathway for the second Michael addition step. The high level of asymmetric induction is rationalized with the help of relative activation barriers associated with the competitive diastereomeric pathways. Interesting weak interactions, along with the steric effects offered by the bulky alpha-substituent on the pyrrolidine ring, are identified as critical to the stereoselectivity in this triple cascade reaction. The predicted stereoselectivities using computed energetics are found to be in perfect harmony with the experimental stereoselectivities.

  16. Cascades in the Threshold Model for varying system sizes

    Science.gov (United States)

    Karampourniotis, Panagiotis; Sreenivasan, Sameet; Szymanski, Boleslaw; Korniss, Gyorgy

    2015-03-01

    A classical model in opinion dynamics is the Threshold Model (TM) aiming to model the spread of a new opinion based on the social drive of peer pressure. Under the TM a node adopts a new opinion only when the fraction of its first neighbors possessing that opinion exceeds a pre-assigned threshold. Cascades in the TM depend on multiple parameters, such as the number and selection strategy of the initially active nodes (initiators), and the threshold distribution of the nodes. For a uniform threshold in the network there is a critical fraction of initiators for which a transition from small to large cascades occurs, which for ER graphs is largerly independent of the system size. Here, we study the spread contribution of each newly assigned initiator under the TM for different initiator selection strategies for synthetic graphs of various sizes. We observe that for ER graphs when large cascades occur, the spread contribution of the added initiator on the transition point is independent of the system size, while the contribution of the rest of the initiators converges to zero at infinite system size. This property is used for the identification of large transitions for various threshold distributions. Supported in part by ARL NS-CTA, ARO, ONR, and DARPA.

  17. Cascaded forward Brillouin scattering to all Stokes orders

    Science.gov (United States)

    Wolff, C.; Stiller, B.; Eggleton, B. J.; Steel, M. J.; Poulton, C. G.

    2017-02-01

    Inelastic scattering processes such as Brillouin scattering can often function in cascaded regimes and this is likely to occur in certain integrated opto-acoustic devices. We develop a Hamiltonian formalism for cascaded Brillouin scattering valid for both quantum and classical regimes. By regarding Brillouin scattering as the interaction of a single acoustic envelope and a single optical envelope that covers all Stokes and anti-Stokes orders, we obtain a compact model that is well suited for numerical implementation, extension to include other optical nonlinearities or short pulses, and application in the quantum-optics domain. We then theoretically analyze intra-mode forward Brillouin scattering (FBS) for arbitrary waveguides with and without optical dispersion. In the absence of optical dispersion, we find an exact analytical solution. With a perturbative approach, we furthermore solve the case of weak optical dispersion. Our work leads to several key results on intra-mode FBS. For negligible dispersion, we show that cascaded intra-mode FBS results in a pure phase modulation and discuss how this necessitates specific experimental methods for the observation of fiber-based and integrated FBS. Further, we discuss how the descriptions that have been established in these two classes of waveguides connect to each other and to the broader context of cavity opto-mechanics and Raman scattering. Finally, we draw an unexpected striking similarity between FBS and discrete diffraction phenomena in waveguide arrays, which makes FBS an interesting candidate for future research in quantum-optics.

  18. A cascaded three-phase symmetrical multistage voltage multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Shahid [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Singh, G K [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Besar, R [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Muhammad, G [Faculty of Information Science and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2006-10-15

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM.

  19. A New Perspective on Trapped Radiation Belts in Planetary Atmospheres

    Science.gov (United States)

    Diaz, A.; Lodhi, M. A. K.; Wilson, T. L.

    2005-01-01

    The charged particle fluxes trapped in the magnetic dipole fields of certain planets in our Solar System are interesting signatures of planetary properties in space physics. They also represent a source of potentially hazardous radiation to spacecraft during planetary and interplanetary exploration. The Earth s trapped radiation belts have been studied for years and the physical mechanisms by which primary radiation from the Sun and Galaxy is captured is well understood. The higher-energy particles collide with molecules in the planetary atmosphere and initiate large cascades of secondary radiation which itself becomes trapped by the magnetic dipole field of the planet. Some of it is even backscattered as albedo neutrons.

  20. Direct Measurements of the Surface-Atmosphere Exchange of Ammonia

    Science.gov (United States)

    Tevlin, A.; Murphy, J. G.; Wentworth, G.; Gregoire, P.

    2012-12-01

    As the dominant atmospheric base, ammonia plays an important role in the formation and growth of inorganic aerosols. Surface-atmosphere exchange of ammonia has been observed to occur as a bidirectional flux governed by the relative magnitudes of atmospheric gas phase concentration and a temperature-dependent surface compensation point. In order to better characterise the links between gas-particle and surface-atmosphere exchanges, more direct measurements of these exchanges are necessary. Eddy Covariance (EC) can provide the most direct surface-atmosphere flux measurements, but its requirement for high frequency data combined with the reactive nature of ammonia have limited its application for this species. In order to address this lack, an investigation into the instrumental sensitivity and time response requirements for EC ammonia flux measurements was carried out using a Quantum Cascade-Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) capable of measuring ammonia concentration at 10 Hz. Time response was additionally improved through the use of a heated sample line and custom glass inlet, and the system was deployed over a short grass field in rural Ontario. The ammonia measurements were used along with three dimensional sonic anemometer wind speed data to calculate EC ammonia fluxes. When combined with simultaneous measurements of the inorganic composition of gas and particle phases made by Ambient Ion Monitor - Ion Chromatography (AIM-IC), these flux measurements can provide insight into the links between gas-particle and surface-atmosphere exchange.