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Sample records for unit burst generator

  1. Leak rate and burst test data for McGuire Unit 1 steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Sherburne, P.A. [B& W Nuclear Service Co., Lynchburg, VA (United States); Frye, C.R. [Babcock & Wilcox Co., Lynchburg, VA (United States); Mayes, D.B. [Duke Power Co., Charlotte, NC (United States)

    1992-12-31

    To support the development of tube plugging criteria that would allow tubes with through-wall cracks to remain in service, sections of 12 tubes were removed from the McGuire Unit-1 steam generators. These tubes were sent to B&W Nuclear Service Company for metallographic examination and for determination of burst pressure and leak rate at both operating and faulted conditions. Primary water stress corrosion cracking (PWSCC) had degraded these tubes in the tube-to-tubesheet roll transitions. To measure primary-to-secondary leakage at pressures and temperatures equivalent to those in the McGuire Unit-1 steam generators, an autoclave-based test loop was designed and installed at the Babcock & Wilcox Lynchburg Research Center. Sections of the tube containing the roll transitions were then installed in the autoclave and actual primary- to-secondary leakage was measured at 288{degrees}C (550{degrees}F) and at 9 and 18.3 MPa (1300 and 2650 psi) pressure differentials. Following the leak test, the tubes were pressurized internally until the tube wall ruptured. Leak rate, burst pressure, and eddy-current information were then correlated with the through-wall crack lengths as determined by metallographic examination. Results confirm the ability to measure the crack length with eddy-current techniques. Results also support analytical and empirical models developed by the nuclear industry in calculating critical crack lengths in roll transitions.

  2. Generating Units

    Data.gov (United States)

    Department of Homeland Security — Generating Units are any combination of physically connected generators, reactors, boilers, combustion turbines, and other prime movers operated together to produce...

  3. United assembly algorithm for optical burst switching

    Institute of Scientific and Technical Information of China (English)

    Jinhui Yu(于金辉); Yijun Yang(杨教军); Yuehua Chen(陈月华); Ge Fan(范戈)

    2003-01-01

    Optical burst switching (OBS) is a promising optical switching technology. The burst assembly algorithm controls burst assembly, which significantly impacts performance of OBS network. This paper provides a new assembly algorithm, united assembly algorithm, which has more practicability than conventional algorithms. In addition, some factors impacting selections of parameters of this algorithm are discussed and the performance of this algorithm is studied by computer simulation.

  4. Space 'beachballs' generate pulsar bursts

    CERN Multimedia

    Wasowicz, L

    2003-01-01

    Researchers have analyzed radio emissions from a pulsar at the center of the Crab Nebula and have found 'subpulses' that last around 2 nanoseconds. They speculate this means the regions in which these ultra-short pulses are generated can be no larger than about 2 feet across - the distance light travels in 2 nanoseconds (2 pages).

  5. Syudy of Token Generation for Burst Traffic Shaping in Optical Burst Switching Networks

    Institute of Scientific and Technical Information of China (English)

    Tang Wan; So Won-ho; Lu Ji-guang; Kim Young-chon

    2004-01-01

    Traffic shaping is one of important control operation to guarantee the Quality of Service (QoS) in optical burst switching (OBS) networks. The efficiency of traffic shaping is mainly determined by token generation method. In this paper, token generation methods of traffic shaping are evaluated by using three kinds of probability distribution, and are analyzed in terms of burst blocking probability, throughput and correlation by simulation. The simulation results show that the token generation methods decrease the burst correlation of Label Switched Paths (LSPs), and solve traffic congestion as well. The different burst arrival processes have small impact on the blocking probability for OBS networks.

  6. Generation of burst time plans for the Intelsat TDMA system

    Science.gov (United States)

    Trusty, P. A.; King, C. A.; Roach, P. W.

    In the Intelsat time-division multiple-access (TDMA) system, the burst time plan (BTP) contains the assignments of traffic and reference bursts, common acquisition windows, and test slots to time slots within the TDMA frame for a given network. Generation of the BTP involves the processes of sub-burst formation, burst formation, reference burst assignments, and burst scheduling. BTP information is transferred to the individual reference and traffic stations in the form of a master time plan (MTP) and a condensed time plan (CTP). This paper describes algorithms which have been developed for each of the BTP generation processes, as well as those algorithms and procedures used to generate the MTPs and CTPs. A software system which implements these algorithms is also discussed.

  7. Dying Flow Bursts as Generators of the Substorm Current Wedge

    Science.gov (United States)

    Haerendel, Gerhard

    2016-07-01

    Many theories or conjectures exist on the driver of the substorm current wedge, e.g. rerouting of the tail current, current disruption, flow braking, vortex formation, and current sheet collapse. Magnitude, spatial scale, and temporal development of the related magnetic perturbations suggest that the generator is related to the interaction of the flow bursts with the dipolar magnetosphere after onset of reconnection in the near-Earth tail. The question remains whether it is the flow energy that feeds the wedge current or the internal energy of the arriving plasma. In this presentation I argue for the latter. The current generation is attributed to the force exerted by the dipolarized magnetic field of the flow bursts on the preceding layer of high-beta plasma after flow braking. The generator current is the grad-B current at the outer boundary of the compressed high-beta plasma layers. It needs the sequential arrival of several flow bursts to account for duration and magnitude of the ionospheric closure current.

  8. UNITED STABILIZING SCHEME FOR EDGE DELAY IN OPTICAL BURST SWITCHED NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel scheme, namely united stabilizing scheme for edge delay, is introduced in optical burst switched networks. In the scheme, the limits of burst length and assembly time are both set according to certain qualifications. For executing the scheme, the conception for unit input bit rate is introduced to improve universality, and the assembly algorithm with a buffer safety space under the self-similar traffic model at each ingress edge router is proposed. Then, the components of burst and packet delay are concluded, and the equations that limits of burst length and assembly time should satisfy to stabilize the burst edge delay under different buffer offered loads are educed. The simulation results show that united stabilizing scheme stabilizes both burst and packet edge delay to a great extent when buffer offered load changes from 0.1 to 1, and the edge delay of burst and packet are near the limit values under larger offered load, respectively.

  9. Research on Mechanism of Rock Burst Generation and Development for High Stress Rock Tunnels

    Institute of Scientific and Technical Information of China (English)

    高全臣; 赫建明; 王代华

    2001-01-01

    Through the investigation and analysis of high stress distribution in surrounding rock during the excavation of rock tunnels,the key factors to cause rock burst and the mechanism of rock burst generation and development are researched. The result shows that the scale and range of rock burst are related with elastic deformation energy storied in rock mass and the characteristics of unloading stress waves. The measures of preventing from rock burst for high stress rock tunnels are put forward.

  10. Generation of circular polarization of gamma ray bursts

    CERN Document Server

    Batebi, S; Ruffini, R; Tizchang, S; Xue, S S

    2016-01-01

    The generation of the circular polarization of Gamma Ray Burst (GRB) photons is discussed in this paper via their interactions with astroparticles in the presence or absence of background fields such as magnetic fields and non-commutative space time geometry. Solving quantum Boltzmann equation for GRB-photons as a photon ensemble, we discuss the generation of circular polarization (as Faraday conversion phase shift $\\Delta \\phi_{FC}$) of GRBs in the following cases: (i) intermediate interactions, i.e. the Compton scattering of GRBs in the galaxy cluster magnetic field and in the presence of non-commutative space time geometry, as well as the scattering of GRBs in cosmic neutrino background (CNB), and in cosmic microwave background (CMB); (ii) interactions with particles and fields in shock wave, i.e. the Compton scattering of GRBs with accelerated charged particles in the presence of magnetic fields. We found that (i) after shock wave crossing, the most contribution of $\\Delta \\phi_{FC}$ for energetic GRBs (i...

  11. Generation of circular polarization of gamma ray bursts

    Science.gov (United States)

    Batebi, S.; Mohammadi, R.; Ruffini, R.; Tizchang, S.; Xue, S.-S.

    2016-09-01

    The generation of the circular polarization of gamma ray burst (GRB) photons is discussed in this paper via their interactions with astroparticles in the presence or absence of background fields such as magnetic fields and noncommutative space-time geometry. Solving the quantum Boltzmann equation for GRB photons as a photon ensemble, we discuss the generation of circular polarization (as Faraday conversion phase shift Δ ϕFC) of GRBs in the following cases: (i) intermediate interactions, i.e., the Compton scattering of GRBs in the galaxy cluster magnetic field and in the presence of noncommutative space-time geometry, as well as the scattering of GRBs in the cosmic neutrino background (CNB) and cosmic microwave background (CMB); (ii) interactions with particles and fields in shockwaves, i.e., the Compton scattering of GRBs with accelerated charged particles in the presence of magnetic fields. We found that (i) after shockwave crossing, the greatest contribution of Δ ϕFC for energetic GRBs (of the order of GeV and larger) comes from GRB-CMB interactions, but for low-energy GRBs the contributions of the Compton scattering of GRBs in the galaxy cluster magnetic field dominate; (ii) in shockwave crossing, the magnetic field has significant effects on converting a GRB's linear polarization to a circular one, and this effect can be used to better understand the magnetic profile in shockwaves. The main aim of this work is to study and measure the circular polarization of GRBs for a better understanding of the physics and mechanism of the generation of GRBs and their interactions before reaching us.

  12. Monolithic fuel cell based power source for burst power generation

    Science.gov (United States)

    Fee, D. C.; Blackburn, P. E.; Busch, D. E.; Dees, D. W.; Dusek, J.; Easler, T. E.; Ellingson, W. A.; Flandermeyer, B. K.; Fousek, R. J.; Heiberger, J. J.

    A unique fuel cell coupled with a low power nuclear reactor presents an attractive approach for SDI burst power requirements. The monolithic fuel cell looks attractive for space applications and represents a quantum jump in fuel cell technology. Such a breakthrough in design is the enabling technology for lightweight, low volume power sources for space based pulse power systems. The monolith is unique among fuel cells in being an all solid state device. The capability for miniaturization, inherent in solid state devices, gives the low volume required for space missions. In addition, the solid oxide fuel cell technology employed in the monolith has high temperature reject heat and can be operated in either closed or open cycles. Both these features are attractive for integration into a burst power system.

  13. Tungsten dust nanoparticles generation from blistering bursts under hydrogen environment in microwave ECR discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ouaras, K., E-mail: ouaras@lspm.cnrs.fr; Hassouni, K.; Delacqua, L. Colina; Lombardi, G.; Vrel, D.; Bonnin, X.

    2015-11-15

    Blistering burst induced tungsten dust nanoparticles were observed for the first time when a tungsten sample is submitted to a hydrogen low-temperature discharge under low flux and low incident energy values (20, 120 and 220 eV) at a surface temperature of 500 K. Tungsten nanoparticles (∼50 nm) were organized in 2D domains with diameter that is well correlated to the blister volume losses by burst. These observations suggest that dust nanoparticles were generated from blistering burst.

  14. Spectral Structures and Their Generation Mechanisms for Solar Radio Type-I Bursts

    CERN Document Server

    Iwai, Kazumasa; Masuda, Satoshi; Tsuchiya, Fuminori; Morioka, Akira; Misawa, Hiroaki

    2014-01-01

    The fine spectral structures of solar radio type-I bursts were observed by the solar radio telescope AMATERAS. The spectral characteristics, such as the peak flux, duration, and bandwidth, of the individual burst elements were satisfactorily detected by the highly resolved spectral data of AMATEAS with the burst detection algorithm that is improved in this study. The peak flux of the type-I bursts followed a power-law distribution with a spectral index of 2.9-3.3, whereas their duration and bandwidth were distributed more exponentially. There were almost no correlations between the peak flux, duration, and bandwidth. That means there were no similarity shapes in the burst spectral structures. We defined the growth rate of a burst as the ratio between its peak flux and duration. There was a strong correlation between the growth rate and peak flux. These results suggest that the free energy of type-I bursts that is originally generated by non-thermal electrons is modulated in the subsequent stages of the genera...

  15. Ligament rupture and unstable burst behaviors of axial flaws in steam generator U-bends

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, Chi Bum, E-mail: bahn@pusan.ac.kr [Pusan National University, 2 Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Oh, Young-Jin [KEPCO Engineering & Construction Co. Inc., Seongnam 463-870 (Korea, Republic of); Majumdar, Saurin [Argonne National Laboratory, Lemont, IL 60439 (United States)

    2015-11-15

    Highlights: • Ligament rupture and unstable burst pressure tests were conducted with U-bends. • In general, U-bends showed higher ligament rupture and burst pressures than straight tubes. • U-bend test data was bounded by 90% lower limit of the probabilistic models for straight tubes. • Prediction models for straight tubes could be conservatively applied to U-bends. - Abstract: Incidents of U-bend cracking in steam generator (SG) tubes have been reported, some of which have led to tube rupture. Experimental and analytical modeling efforts to determine the failure criteria of flawed SG U-bends are limited. To evaluate structural integrity of flawed U-bends, ligament rupture and unstable burst pressure tests were conducted on 57 and 152 mm bend radius U-bends with axial electrical discharge machining notches. In general, the ligament rupture and burst pressures of the U-bends were higher than those of straight tubes with similar notches. To quantitatively address the test data scatter issue, probabilistic models were introduced. All ligament rupture and burst pressures of U-bends were bounded by 90% lower limits of the probabilistic models for straight tubes. It was concluded that the prediction models for straight tubes could be applied to U-bends to conservatively evaluate the ligament rupture and burst pressures of U-bends with axial flaws.

  16. Formation and characterization of the vortices generated by a DBD plasma actuator in burst mode

    Science.gov (United States)

    Mishra, Bal Krishan; Panigrahi, P. K.

    2017-02-01

    The present study reports the formation and evolution characteristics of the continuously generated vortical structure and resulting flow field in quiescent air induced by a dielectric-barrier-discharge (DBD) plasma actuator in burst mode operation. A starting vortex is formed during the initial actuation period, which disappears after a small time interval for continuous mode operation of the DBD plasma actuator. A burst input signal to the actuator generates a train of self-similar vortices. The behaviour of vortices and the average flow field induced by the actuator has been studied using high speed schlieren visualization and particle image velocimetry technique for different actuation amplitude and duty cycle parameters. These repeating vortices travel faster than the starting vortex, and the vortex core velocity of these repeating vortices increases with increase in duty cycle parameter. Fuller u-velocity profile, higher v-velocity near the edge of the outer shear layer region, and higher growth of the wall jet thickness is observed due to enhanced entrainment by repeating vortices for burst mode operation. The repeating vortices travel at an angle of 21° relative to the wall surface for duty cycle parameter of 90.9% in comparison to 31° for the starting vortex. Self-similarity of the velocity profile is delayed in the streamwise direction for burst mode operation in comparison to that for the continuous mode of operation. This can be attributed to delay in attaining the maximum velocity of the wall jet profile and presence of coherent structures for the burst mode operation. The non-dimensional vortex core location and size for repeating vortices follow power law fit similar to the starting vortex with difference in value of the power law exponent. The phase difference between the input voltage and current drawn is in the range of π/12 to π/9 (in radians) for both continuous and burst mode operation indicating identical electrical behaviour of the

  17. Generation of intense circularly polarized attosecond light bursts from relativistic laser plasmas

    CERN Document Server

    Ma, Guangjin; Yu, M Y; Shen, Baifei; Veisz, Laszlo

    2016-01-01

    We have investigated the polarization of attosecond light bursts generated by nanobunches of electrons from relativistic few-cycle laser pulse interaction with the surface of overdense plasmas. Particle-in-cell simulation shows that the polarization state of the generated attosecond burst depends on the incident-pulse polarization, duration, carrier envelope phase, as well as the plasma scale length. Through laser and plasma parameter control, without compromise of generation efficiency, a linearly polarized laser pulse with azimuth $\\theta^i=10^\\circ$ can generate an elliptically polarized attosecond burst with azimuth $|\\theta^r_{\\rm atto}|\\approx61^\\circ$ and ellipticity $\\sigma^r_{\\rm atto}\\approx0.27$; while an elliptically polarized laser pulse with $\\sigma^i\\approx0.36$ can generate an almost circularly polarized attosecond burst with $\\sigma^r_{\\rm atto}\\approx0.95$. The results propose a new way to a table-top circularly polarized XUV source as a probe with attosecond scale time resolution for many a...

  18. Burst-generating neurones in the dorsal horn in an in vitro preparation of the turtle spinal cord

    DEFF Research Database (Denmark)

    Russo, R E; Hounsgaard, J

    1996-01-01

    horn, was distinguished by the ability to generate a burst response following a hyperpolarization from rest or during a depolarization from a hyperpolarized holding potential. The burst response was inactivated at the resting membrane potential. 3. The burst response was mediated by a low threshold Ca2......+ spike assumed to be mediated by T-type Ca2+ channels since it resisted tetrodotoxin and was blocked by 3 mM Co2+ or 100-300 microM Ni2+ and resembled the low threshold spike (LTS) described elsewhere. 4. Some burst-generating cells also displayed plateau potentials mediated by L-type Ca2+ channels....... In these cells the burst following a hyperpolarizing current pulse, applied from the resting membrane potential, facilitated the activation of the plateau potential. Wind-up of the plateau potential was produced when the hyperpolarizing pulse generating the burst was repeated at 0.1-0.3 Hz or faster. 5...

  19. Asymmetry Factors Shaping Regular and Irregular Bursting Rhythms in Central Pattern Generators

    Science.gov (United States)

    Elices, Irene; Varona, Pablo

    2017-01-01

    Central Pattern Generator (CPG) circuits are neural networks that generate rhythmic motor patterns. These circuits are typically built of half-center oscillator subcircuits with reciprocally inhibitory connections. Another common property in many CPGs is the remarkable rich spiking-bursting dynamics of their constituent cells, which balance robustness and flexibility to generate their joint coordinated rhythms. In this paper, we use conductance-based models and realistic connection topologies inspired by the crustacean pyloric CPG to address the study of asymmetry factors shaping CPG bursting rhythms. In particular, we assess the role of asymmetric maximal synaptic conductances, time constants and gap-junction connectivity to establish the regularity of half-center oscillator based CPGs. We map and characterize the synaptic parameter space that lead to regular and irregular bursting activity in these networks. The analysis indicates that asymmetric configurations display robust regular rhythms and that large regions of both regular and irregular but coordinated rhythms exist as a function of the asymmetry in the circuit. Our results show that asymmetry both in the maximal conductances and in the temporal dynamics of mutually inhibitory neurons can synergistically contribute to shape wide regimes of regular spiking-bursting activity in CPGs. Finally, we discuss how a closed-loop protocol driven by a regularity goal can be used to find and characterize regular regimes when there is not time to perform an exhaustive search, as in most experimental studies. PMID:28261081

  20. Mechanisms underlying burst generation of the pyloric muscle in the mantis shrimp, Squilla oratoria.

    Science.gov (United States)

    Tazaki, K; Chiba, C

    1991-12-01

    The pyloric constrictor muscles of the stomach in Squilla can generate spikes by synaptic activation via the motor nerve from the stomatogastric ganglion. Spikes are followed by slow depolarizing afterpotentials (DAPs) which lead to sustained depolarization during a burst of spikes. 1. The frequency of rhythmic bursts induced by continuous depolarization is membrane voltage-dependent. A brief depolarizing or hyperpolarizing pulse can trigger or terminate bursts, respectively, in a threshold-dependent manner. 2. The conductance increases during the DAP response. The amplitude of DAP decreases by imposed depolarization, whereas it increases by hyperpolarization. DAPs from successive spikes sum to produce a sustained depolarizing potential capable of firing a burst. 3. The spike and DAP are reduced in amplitude by decreasing [Ca]o, enhanced by Sr2+ or Ba2+ substituted for Ca2+, and blocked by Co2+ or Mn2+. DAPs are selectively blocked by Ni2+, and the spike is followed by a hyperpolarizing afterpotential. 4. The spike and DAP are prolonged by intracellular injection of the Ca2+ chelator EGTA. A hyperpolarizing afterpotential is abolished by EGTA and enhanced by increasing [Ca]o. The DAP is diminished in Na(+)-free saline and reduced by tetrodotoxin. 5. It is concluded that the muscle fiber is endowed with endogenous oscillatory properties and that the oscillatory membrane events result from changes of a voltage- and time-dependent conductance to Ca2+ and Na+ and a Ca2+ activated conductance to K+.

  1. A Lognormal Recurrent Network Model for Burst Generation during Hippocampal Sharp Waves.

    Science.gov (United States)

    Omura, Yoshiyuki; Carvalho, Milena M; Inokuchi, Kaoru; Fukai, Tomoki

    2015-10-28

    The strength of cortical synapses distributes lognormally, with a long tail of strong synapses. Various properties of neuronal activity, such as the average firing rates of neurons, the rate and magnitude of spike bursts, the magnitude of population synchrony, and the correlations between presynaptic and postsynaptic spikes, also obey lognormal-like distributions reported in the rodent hippocampal CA1 and CA3 areas. Theoretical models have demonstrated how such a firing rate distribution emerges from neural network dynamics. However, how the other properties also display lognormal patterns remain unknown. Because these features are likely to originate from neural dynamics in CA3, we model a recurrent neural network with the weights of recurrent excitatory connections distributed lognormally to explore the underlying mechanisms and their functional implications. Using multi-timescale adaptive threshold neurons, we construct a low-frequency spontaneous firing state of bursty neurons. This state well replicates the observed statistical properties of population synchrony in hippocampal pyramidal cells. Our results show that the lognormal distribution of synaptic weights consistently accounts for the observed long-tailed features of hippocampal activity. Furthermore, our model demonstrates that bursts spread over the lognormal network much more effectively than single spikes, implying an advantage of spike bursts in information transfer. This efficiency in burst propagation is not found in neural network models with Gaussian-weighted recurrent excitatory synapses. Our model proposes a potential network mechanism to generate sharp waves in CA3 and associated ripples in CA1 because bursts occur in CA3 pyramidal neurons most frequently during sharp waves.

  2. Laboratory-generated primary marine aerosol via bubble-bursting and atomization

    Directory of Open Access Journals (Sweden)

    E. Fuentes

    2009-09-01

    Full Text Available A range of bubble and sea spray aerosol generators has been tested in the laboratory and compared with ocean measurements. We have shown that the method of generation has a significant influence on the properties of the aerosol particles produced. Hence, the validity of a generation system to mimic atmospheric aerosol is dependent on its capacity of generating bubbles and particulate in a realistic manner. A bubble-bursting aerosol generator consisting in the production of bubbles by the impingement of water jets on seawater was shown to best reproduce the real oceanic bubble and aerosol distributions signatures.

    Two aeration methods and a plunging-water jet system were tested as bubble-bursting aerosol generators for comparison with a standard nebulizer. The methods for aerosol production were evaluated by analysing the bubble spectrum generated by the bubble-bursting systems and the submicron size distribution, hygroscopicity and cloud condensation nucleus activity of the aerosols generated by the different techniques. Significant differences in the bubble spectrum and aerosol properties were observed when using different aerosol generators.

    The hygroscopicity and cloud condensation nucleus activity of aerosols generated by the different methods were similar when a sample of purely inorganic salts was used as a parent seawater solution; however, significant differences in the aerosol properties were found when biogenic organics were incorporated in the seawater samples. The presence of organics in the aerosol caused suppression of the growth factor at humidities above 75% RH and an increase in the critical supersaturation when compared with the case without organics. Unequal extent of these effects was observed for aerosols generated by the different methods of particle production. While the highest reductions of the growth factor were observed for the plunging-water jet aerosol, the largest effect on the critical

  3. Dopamine-deprived striatal GABAergic interneurons burst and generate repetitive gigantic IPSCs in medium spiny neurons.

    Science.gov (United States)

    Dehorter, Nathalie; Guigoni, Celine; Lopez, Catherine; Hirsch, June; Eusebio, Alexandre; Ben-Ari, Yehezkel; Hammond, Constance

    2009-06-17

    Striatal GABAergic microcircuits modulate cortical responses and movement execution in part by controlling the activity of medium spiny neurons (MSNs). How this is altered by chronic dopamine depletion, such as in Parkinson's disease, is not presently understood. We now report that, in dopamine-depleted slices of the striatum, MSNs generate giant spontaneous postsynaptic GABAergic currents (single or in bursts at 60 Hz) interspersed with silent episodes, rather than the continuous, low-frequency GABAergic drive (5 Hz) observed in control MSNs. This shift was observed in one-half of the MSN population, including both "D(1)-negative" and "D(1)-positive" MSNs. Single GABA and NMDA channel recordings revealed that the resting membrane potential and reversal potential of GABA were similar in control and dopamine-depleted MSNs, and depolarizing, but not excitatory, actions of GABA were observed. Glutamatergic and cholinergic antagonists did not block the GABAergic oscillations, suggesting that they were generated by GABAergic neurons. In support of this, cell-attached recordings revealed that a subpopulation of intrastriatal GABAergic interneurons generated bursts of spikes in dopamine-deprived conditions. This subpopulation included low-threshold spike interneurons but not fast-spiking interneurons, cholinergic interneurons, or MSNs. Therefore, a population of local GABAergic interneurons shifts from tonic to oscillatory mode when dopamine deprived and gives rise to spontaneous repetitive giant GABAergic currents in one-half the MSNs. We suggest that this may in turn alter integration of cortical signals by MSNs.

  4. Simultaneous ultrafast optical pulse train bursts generation and shaping based on Fourier series developments using superimposed fiber Bragg gratings.

    Science.gov (United States)

    García-Muñoz, Víctor; Preciado, Miguel A; Muriel, Miguel A

    2007-08-20

    We propose an all-fiber method for the generation of ultrafast shaped pulse train bursts from a single pulse based on Fourier Series Developments (FDSs). The implementation of the FSD based filter only requires the use of a very simple non apodized Superimposed Fiber Bragg Grating (S-FBG) for the generation of the Shaped Output Pulse Train Burst (SOPTB). In this approach, the shape, the period and the temporal length of the generated SOPTB have no dependency on the input pulse rate.

  5. PERFORMANCE ANALYSIS AND SIMULATION OF VARIOUS BURST TIME PLAN GENERATION METHODS IN BROADBAND SATELLITE MULTIMEDIA SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Feng Shaodong; Li Guangxia; Feng Qi

    2011-01-01

    The Burst Time Plan (BTP) generation is the key for resource allocation in Broadband Satellite Multimedia (BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service (QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation (P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation (O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation (A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite (DVB-RCS) system or IP onboard routing BSM system in the future.

  6. Generating units performances: power system requirements

    Energy Technology Data Exchange (ETDEWEB)

    Fourment, C.; Girard, N.; Lefebvre, H.

    1994-08-01

    The part of generating units within the power system is more than providing power and energy. Their performance are not only measured by their energy efficiency and availability. Namely, there is a strong interaction between the generating units and the power system. The units are essential components of the system: for a given load profile the frequency variation follows directly from the behaviour of the units and their ability to adapt their power output. In the same way, the voltage at the units terminals are the key points to which the voltage profile at each node of the network is linked through the active and especially the reactive power flows. Therefore, the customer will experience the frequency and voltage variations induced by the units behaviour. Moreover, in case of adverse conditions, if the units do not operate as well as expected or trip, a portion of the system, may be the whole system, may collapse. The limitation of the performance of a unit has two kinds of consequences. Firstly, it may result in an increased amount of not supplied energy or loss of load probability: for example if the primary reserve is not sufficient, a generator tripping may lead to an abnormal frequency deviation, and load may have to be shed to restore the balance. Secondly, the limitation of a unit performance results in an economic over-cost for the system: for instance, if not enough `cheap` units are able to load-following, other units with higher operating costs have to be started up. We would like to stress the interest for the operators and design teams of the units on the one hand, and the operators and design teams of the system on the other hand, of dialog and information exchange, in operation but also at the conception stage, in order to find a satisfactory compromise between the system requirements and the consequences for the generating units. (authors). 11 refs., 4 figs.

  7. Generation of femtosecond γ-ray bursts stimulated by laser-driven hosing evolution

    Science.gov (United States)

    Ma, Yong; Chen, Liming; Li, Dazhang; Yan, Wenchao; Huang, Kai; Chen, Min; Sheng, Zhengming; Nakajima, Kazuhisa; Tajima, Toshiki; Zhang, Jie

    2016-07-01

    The promising ability of a plasma wiggler based on laser wakefield acceleration to produce betatron X-rays with photon energies of a few keV to hundreds of keV and a peak brilliance of 1022-1023 photons/s/mm2/mrad2/0.1%BW has been demonstrated, providing an alternative to large-scale synchrotron light sources. Most methods for generating betatron radiation are based on two typical approaches, one relying on an inherent transverse focusing electrostatic field, which induces transverse oscillation, and the other relying on the electron beam catching up with the rear part of the laser pulse, which results in strong electron resonance. Here, we present a new regime of betatron γ-ray radiation generated by stimulating a large-amplitude transverse oscillation of a continuously injected electron bunch through the hosing of the bubble induced by the carrier envelope phase (CEP) effect of the self-steepened laser pulse. Our method increases the critical photon energy to the MeV level, according to the results of particle-in-cell (PIC) simulations. The highly collimated, energetic and femtosecond γ-ray bursts that are produced in this way may provide an interesting potential means of exploring nuclear physics in table top photo nuclear reactions.

  8. Key bifurcations of bursting polyrhythms in 3-cell central pattern generators.

    Directory of Open Access Journals (Sweden)

    Jeremy Wojcik

    Full Text Available We identify and describe the key qualitative rhythmic states in various 3-cell network motifs of a multifunctional central pattern generator (CPG. Such CPGs are neural microcircuits of cells whose synergetic interactions produce multiple states with distinct phase-locked patterns of bursting activity. To study biologically plausible CPG models, we develop a suite of computational tools that reduce the problem of stability and existence of rhythmic patterns in networks to the bifurcation analysis of fixed points and invariant curves of a Poincaré return maps for phase lags between cells. We explore different functional possibilities for motifs involving symmetry breaking and heterogeneity. This is achieved by varying coupling properties of the synapses between the cells and studying the qualitative changes in the structure of the corresponding return maps. Our findings provide a systematic basis for understanding plausible biophysical mechanisms for the regulation of rhythmic patterns generated by various CPGs in the context of motor control such as gait-switching in locomotion. Our analysis does not require knowledge of the equations modeling the system and provides a powerful qualitative approach to studying detailed models of rhythmic behavior. Thus, our approach is applicable to a wide range of biological phenomena beyond motor control.

  9. Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

    CERN Document Server

    Yuan, Weimin; Cannizzo, John K; Cordier, Bertrand; Gehrels, Neil; Ghirlanda, Giancarlo; Götz, Diego; Produit, Nicolas; Qiu, Yulei; Sun, Jianchao; Tanvir, Nial R; Wei, Jianyan; Zhang, Chen

    2016-01-01

    High-redshift Gamma-Ray Bursts (GRBs) beyond redshift $\\sim6$ are potentially powerful tools to probe the distant early Universe. Their detections in large numbers and at truly high redshifts call for the next generation of high-energy wide-field instruments with unprecedented sensitivity at least one order of magnitude higher than the ones currently in orbit. On the other hand, follow-up observations of the afterglows of high-redshift GRBs and identification of their host galaxies, which would be difficult for the currently operating telescopes, require new, extremely large facilities of at multi-wavelengths. This chapter describes future experiments that are expected to advance this exciting field, both being currently built and being proposed. The legacy of Swift will be continued by SVOM, which is equipped with a set of space-based multi-wavelength instruments as well as and a ground segment including a wide angle camera and two follow-up telescopes. The established Lobster-eye X-ray focusing optics provi...

  10. ZFP36L2 is required for self-renewal of early burst-forming unit erythroid progenitors.

    Science.gov (United States)

    Zhang, Lingbo; Prak, Lina; Rayon-Estrada, Violeta; Thiru, Prathapan; Flygare, Johan; Lim, Bing; Lodish, Harvey F

    2013-07-04

    Stem cells and progenitors in many lineages undergo self-renewing divisions, but the extracellular and intracellular proteins that regulate this process are largely unknown. Glucocorticoids stimulate red blood cell formation by promoting self-renewal of early burst-forming unit-erythroid (BFU-E) progenitors. Here we show that the RNA-binding protein ZFP36L2 is a transcriptional target of the glucocorticoid receptor (GR) in BFU-Es and is required for BFU-E self-renewal. ZFP36L2 is normally downregulated during erythroid differentiation from the BFU-E stage, but its expression is maintained by all tested GR agonists that stimulate BFU-E self-renewal, and the GR binds to several potential enhancer regions of ZFP36L2. Knockdown of ZFP36L2 in cultured BFU-E cells did not affect the rate of cell division but disrupted glucocorticoid-induced BFU-E self-renewal, and knockdown of ZFP36L2 in transplanted erythroid progenitors prevented expansion of erythroid lineage progenitors normally seen following induction of anaemia by phenylhydrazine treatment. ZFP36L2 preferentially binds to messenger RNAs that are induced or maintained at high expression levels during terminal erythroid differentiation and negatively regulates their expression levels. ZFP36L2 therefore functions as part of a molecular switch promoting BFU-E self-renewal and a subsequent increase in the total numbers of colony-forming unit-erythroid (CFU-E) progenitors and erythroid cells that are generated.

  11. Bursts from GS 1826-238 a clocked thermonuclear flashes generator

    CERN Document Server

    Ubertini, P; Cocchi, M; Natalucci, L; Heise, J; Müller, J M; in 't Zand, J J M

    1999-01-01

    The transient X-ray source GS 1826-238 was monitored during five different observing periods between August 1996 and October 1998 with the BeppoSAX Wide Field Camera instrument in the framework of a deep observation of the Galactic Center region. A first detection of X-ray bursts from this source occurred, ruling out its previously suggested black hole candidacy and strongly suggesting the compact object to be a weakly magnetized neutron star. During the 2.5 years of monitoring, corresponding to ~2.0 Ms observing time, 70 bursts were detected from the source. We here report a quasi-periodicity of 5.76 h in the burst occurrence time which is present during all observations. This is the first example of quasi-periodic bursting over a period of years. It is in line with the history of a rather constant flux since the turn on in 1988 and points to a very stable accretion.

  12. Geothermal power generation in United States

    Science.gov (United States)

    Braun, Gerald W.; McCluer, H. K.

    1993-03-01

    Geothermal energy is an indigenous environmentally benign heat source with the potential for 5000-10,000 GWe of power generation in the United States. Approximately 2535 MWe of installed capacity is currently operating in the U.S. with contracted power costs down to 4.6 cents/kWh. This paper summarizes: 1) types of geothermal resources; 2) power conversion systems used for geothermal power generation; 3) environmental aspects; 4) geothermal resource locations, potential, and current power plant development; 5) hurdles, bottlenecks, and risks of geothermal power production; 6) lessons learned; and 7) ongoing and future geothermal research programs.

  13. Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

    Science.gov (United States)

    Yuan, Weimin; Amati, Lorenzo; Cannizzo, John K.; Cordier, Bertrand; Gehrels, Neil; Ghirlanda, Giancarlo; Götz, Diego; Produit, Nicolas; Qiu, Yulei; Sun, Jianchao; Tanvir, Nial R.; Wei, Jianyan; Zhang, Chen

    2016-12-01

    High-redshift Gamma-Ray Bursts (GRBs) beyond redshift {˜}6 are potentially powerful tools to probe the distant early Universe. Their detections in large numbers and at truly high redshifts call for the next generation of high-energy wide-field instruments with unprecedented sensitivity at least one order of magnitude higher than the ones currently in orbit. On the other hand, follow-up observations of the afterglows of high-redshift GRBs and identification of their host galaxies, which would be difficult for the currently operating telescopes, require new, extremely large facilities of at multi-wavelengths. This chapter describes future experiments that are expected to advance this exciting field, both being currently built and being proposed. The legacy of Swift will be continued by SVOM, which is equipped with a set of space-based multi-wavelength instruments as well as and a ground segment including a wide angle camera and two follow-up telescopes. The established Lobster-eye X-ray focusing optics provides a promising technology for the detection of faint GRBs at very large distances, based on which the THESEUS, Einstein Probe and other mission concepts have been proposed. Follow-up observations and exploration of the reionization era will be enabled by large facilities such as SKA in the radio, the 30 m class telescopes in the optical/near-IR, and the space-borne WFIRST and JWST in the optical/near-IR/mid-IR. In addition, the X-ray and γ-ray polarization experiment POLAR is also introduced.

  14. Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

    Science.gov (United States)

    Yuan, Weimin; Amati, Lorenzo; Cannizzo, John K.; Cordier, Bertrand; Gehrels, Neil; Ghirlanda, Giancarlo; Götz, Diego; Produit, Nicolas; Qiu, Yulei; Sun, Jianchao; Tanvir, Nial R.; Wei, Jianyan; Zhang, Chen

    2016-07-01

    High-redshift Gamma-Ray Bursts (GRBs) beyond redshift {˜}6 are potentially powerful tools to probe the distant early Universe. Their detections in large numbers and at truly high redshifts call for the next generation of high-energy wide-field instruments with unprecedented sensitivity at least one order of magnitude higher than the ones currently in orbit. On the other hand, follow-up observations of the afterglows of high-redshift GRBs and identification of their host galaxies, which would be difficult for the currently operating telescopes, require new, extremely large facilities of at multi-wavelengths. This chapter describes future experiments that are expected to advance this exciting field, both being currently built and being proposed. The legacy of Swift will be continued by SVOM, which is equipped with a set of space-based multi-wavelength instruments as well as and a ground segment including a wide angle camera and two follow-up telescopes. The established Lobster-eye X-ray focusing optics provides a promising technology for the detection of faint GRBs at very large distances, based on which the THESEUS, Einstein Probe and other mission concepts have been proposed. Follow-up observations and exploration of the reionization era will be enabled by large facilities such as SKA in the radio, the 30 m class telescopes in the optical/near-IR, and the space-borne WFIRST and JWST in the optical/near-IR/mid-IR. In addition, the X-ray and γ-ray polarization experiment POLAR is also introduced.

  15. Interaction between cellular voltage-sensitive conductance and network parameters in a model of neocortex can generate epileptiform bursting.

    Energy Technology Data Exchange (ETDEWEB)

    van Drongelen, W.; Lee, H. C.; Koch, H.; Elsen, F.; Carroll, M. S.; Hereld, M.; Stevens, R. L.; Mathematics and Computer Science; Univ. of Chicago

    2004-01-01

    We examined the effects of both intrinsic neuronal membrane properties and network parameters on oscillatory activity in a model of neocortex. A scalable network model with six different cell types was built with the pGENESIS neural simulator. The neocortical network consisted of two types of pyramidal cells and four types of inhibitory interneurons. All cell types contained both fast sodium and delayed rectifier potassium channels for generation of action potentials. A subset of the pyramidal neurons contained an additional slow inactivating (persistent) sodium current (NaP). The neurons with the NaP current showed spontaneous bursting activity in the absence of external stimulation. The model also included a routine to calculate a simulated electroencephalogram (EEG) trace from the population activity. This revealed emergent network behavior which ranged from desynchronized activity to different types of seizure-like bursting patterns. At settings with weaker excitatory network effects, the propensity to generate seizure-like behavior increased. Strong excitatory network connectivity destroyed oscillatory behavior, whereas weak connectivity enhanced the relative importance of the spontaneously bursting cells. Our findings are in contradiction with the general opinion that strong excitatory synaptic and/or insufficient inhibition effects are associated with seizure initiation, but are in agreement with previously reported behavior in neocortex.

  16. Analysis on Operation Reliability of Generating Units in 2009

    Institute of Scientific and Technical Information of China (English)

    Zhou

    2010-01-01

    This paper presents the data on operation reliability indices and relevant analyses toward China's conventional power generating units in 2009. The units brought into the statistical analysis include 100-MW or above thermal generating units, 40-MW or above hydro generating units, and all nuclear generating units. The reliability indices embodied include utilization hours, times and hours of scheduled outages, times and hours of unscheduled outages, equivalent forced outage rate and equivalent availability factor.

  17. Up to 400 GHz burst-mode pulse generation from a hybrid harmonic mode-locked Er-doped fibre laser

    Science.gov (United States)

    Wang, Sheng-Min; Lai, Yinchieh

    2017-02-01

    By inserting a birefringence filter with FSR  =  100 GHz inside a hybrid mode-locked Er-doped fibre laser, we successfully generate ps to sub-ps optical burst pulses with the intra-burst pulse rate up to 400 GHz. Multiplication of the intra-burst pulse rate is attributed to a new effect analogous to rational harmonic mode-locking, which occurs due to the relative alignment of the cavity harmonic frequencies, the external phase modulation induced frequencies, and the filter-selected frequencies.

  18. Burst Mechanisms in Hydrodynamics

    CERN Document Server

    Knobloch, E

    1999-01-01

    Different mechanisms believed to be responsible for the generation of bursts in hydrodynamical systems are reviewed and a new mechanism capable of generating regular or irregular bursts of large dynamic range near threshold is described. The new mechanism is present in the interaction between oscillatory modes of odd and even parity in systems of large but finite aspect ratio, and provides an explanation for the bursting behavior observed in binary fluid convection. Additional applications of the new mechanism are proposed.

  19. FLARE-GENERATED TYPE II BURST WITHOUT ASSOCIATED CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Magdalenic, J.; Marque, C.; Zhukov, A. N. [Solar-Terrestrial Center of Excellence, SIDC, Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Brussels (Belgium); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, HR-10000 Zagreb (Croatia); Veronig, A., E-mail: Jasmina.Magdalenic@oma.be [IGAM/Kanzelhoehe Observatory, Institut of Physics, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

    2012-02-20

    We present a study of the solar coronal shock wave on 2005 November 14 associated with the GOES M3.9 flare that occurred close to the east limb (S06 Degree-Sign E60 Degree-Sign ). The shock signature, a type II radio burst, had an unusually high starting frequency of about 800 MHz, indicating that the shock was formed at a rather low height. The position of the radio source, the direction of the shock wave propagation, and the coronal electron density were estimated using Nancay Radioheliograph observations and the dynamic spectrum of the Green Bank Solar Radio Burst Spectrometer. The soft X-ray, H{alpha}, and Reuven Ramaty High Energy Solar Spectroscopic Imager observations show that the flare was compact, very impulsive, and of a rather high density and temperature, indicating a strong and impulsive increase of pressure in a small flare loop. The close association of the shock wave initiation with the impulsive energy release suggests that the impulsive increase of the pressure in the flare was the source of the shock wave. This is supported by the fact that, contrary to the majority of events studied previously, no coronal mass ejection was detected in association with the shock wave, although the corresponding flare occurred close to the limb.

  20. Polygenetic Aspect of Unit Theory Oil Generation

    Science.gov (United States)

    Galant, Yuri

    2015-04-01

    In the framework of a unified theory Oil Generation one of important moments is the consideration of the distribution of oil in the Earth's Crust. Analysis of the distribution of oil deposits in the Earth's Crust showed that oil distributed throughout the stratigraphic section from ancient to modern sediments and from a depth of 12 kilometers to the Earth's surface. The distribution of oil almost meets all stages of metamorphism of rocks. Correlation of the section of oil distribution to genetic types of ore deposits showed that each genetic type ore deposits has its analogue oil field . So it is possible to classify oil fields on 1) endogenous: the actual magmatic, post-magmatic, contact-metasomatic (skarn), hydrothermal, exhalation, carbonatite, pegmatite, 2) exogenous: weathering, oxidation, sedimentary,3) metamorphogenic: metamorphosed, metamorphic. Model of such distribution of oil deposits can be a process of successive formation of oil deposits of mantle degassing tube. Thus oil is polygenic by way of formation of deposits, but their source is united.

  1. Feasibility of a Small, Rapid Optical-to-IR Response, Next Generation Gamma Ray Burst Mission

    CERN Document Server

    Grossan, B; Bogomolov, V V; Svertilov, S I; Vedenkin, N N; Panasyuk, M; Goncharov, B; Rozhkov, G; Saleev, K; Grobovskoj, E; Krasnov, A S; Morozenko, V S; Osedlo, V I; Rogkov, E; Vachenko, T V; Linder, E V

    2013-01-01

    We present motivations for and study feasibility of a small, rapid optical to IR response gamma ray burst (GRB) space observatory. By analyzing existing GRB data, we give realistic detection rates for X-ray and optical/IR instruments of modest size under actual flight conditions. Given new capabilities of fast optical/IR response (about 1 s to target) and simultaneous multi-band imaging, such an observatory can have a reasonable event rate, likely leading to new science. Requiring a Swift-like orbit, duty cycle, and observing constraints, a Swift-BAT scaled down to 190 square cm of detector area would still detect and locate about 27 GRB per yr. for a trigger threshold of 6.5 sigma. About 23 percent of X-ray located GRB would be detected optically for a 10 cm diameter instrument (about 6 per yr. for the 6.5 sigma X-ray trigger).

  2. Intrinsic and synaptic dynamics interact to generate emergent patterns of rhythmic bursting in thalamocortical neurons.

    Science.gov (United States)

    Sohal, Vikaas S; Pangratz-Fuehrer, Susanne; Rudolph, Uwe; Huguenard, John R

    2006-04-19

    Rhythmic inhibition entrains the firing of excitatory neurons during oscillations throughout the brain. Previous work has suggested that the strength and duration of inhibitory input determines the synchrony and period, respectively, of these oscillations. In particular, sleep spindles result from a cycle of events including rhythmic inhibition and rebound bursts in thalamocortical (TC) neurons, and slowing and strengthening this inhibitory input may transform spindles into spike-wave discharges characteristic of absence epilepsy. Here, we used dynamic clamp to inject TC neurons with spindle-like trains of IPSCs and studied how modest changes in the amplitude and/or duration of these IPSCs affected the responses of the TC neurons. Contrary to our expectations, we found that prolonging IPSCs accelerates postinhibitory rebound (PIR) in TC neurons, and that increasing either the amplitude or duration of IPSCs desynchronizes PIR activity in a population of TC cells. Tonic injection of hyperpolarizing or depolarizing current dramatically alters the timing and synchrony of PIR. These results demonstrate that rhythmic PIR activity is an emergent property of interactions between intrinsic and synaptic currents, not just a passive reflection of incoming synaptic inhibition.

  3. Effects of bursting dynamic features on the generation of multi-clustered structure of neural network with symmetric spike-timing-dependent plasticity learning rule

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui; Song, Yongduan; Xue, Fangzheng; Li, Xiumin, E-mail: xmli@cqu.edu.cn [Key Laboratory of Dependable Service Computing in Cyber Physical Society of Ministry of Education, Chongqing University, Chongqing 400044 (China); College of Automation, Chongqing University, Chongqing 400044 (China)

    2015-11-15

    In this paper, the generation of multi-clustered structure of self-organized neural network with different neuronal firing patterns, i.e., bursting or spiking, has been investigated. The initially all-to-all-connected spiking neural network or bursting neural network can be self-organized into clustered structure through the symmetric spike-timing-dependent plasticity learning for both bursting and spiking neurons. However, the time consumption of this clustering procedure of the burst-based self-organized neural network (BSON) is much shorter than the spike-based self-organized neural network (SSON). Our results show that the BSON network has more obvious small-world properties, i.e., higher clustering coefficient and smaller shortest path length than the SSON network. Also, the results of larger structure entropy and activity entropy of the BSON network demonstrate that this network has higher topological complexity and dynamical diversity, which benefits for enhancing information transmission of neural circuits. Hence, we conclude that the burst firing can significantly enhance the efficiency of clustering procedure and the emergent clustered structure renders the whole network more synchronous and therefore more sensitive to weak input. This result is further confirmed from its improved performance on stochastic resonance. Therefore, we believe that the multi-clustered neural network which self-organized from the bursting dynamics has high efficiency in information processing.

  4. Effects of bursting dynamic features on the generation of multi-clustered structure of neural network with symmetric spike-timing-dependent plasticity learning rule

    Science.gov (United States)

    Liu, Hui; Song, Yongduan; Xue, Fangzheng; Li, Xiumin

    2015-11-01

    In this paper, the generation of multi-clustered structure of self-organized neural network with different neuronal firing patterns, i.e., bursting or spiking, has been investigated. The initially all-to-all-connected spiking neural network or bursting neural network can be self-organized into clustered structure through the symmetric spike-timing-dependent plasticity learning for both bursting and spiking neurons. However, the time consumption of this clustering procedure of the burst-based self-organized neural network (BSON) is much shorter than the spike-based self-organized neural network (SSON). Our results show that the BSON network has more obvious small-world properties, i.e., higher clustering coefficient and smaller shortest path length than the SSON network. Also, the results of larger structure entropy and activity entropy of the BSON network demonstrate that this network has higher topological complexity and dynamical diversity, which benefits for enhancing information transmission of neural circuits. Hence, we conclude that the burst firing can significantly enhance the efficiency of clustering procedure and the emergent clustered structure renders the whole network more synchronous and therefore more sensitive to weak input. This result is further confirmed from its improved performance on stochastic resonance. Therefore, we believe that the multi-clustered neural network which self-organized from the bursting dynamics has high efficiency in information processing.

  5. An improvement in perception of self-generated tactile stimuli following theta-burst stimulation of primary motor cortex

    Science.gov (United States)

    Voss, Martin; Bays, Paul M.; Rothwell, John C.; Wolpert, Daniel M.

    2007-01-01

    Recent studies have shown that self-generated tactile sensations are perceived as weaker than the same sensations externally generated. This has been linked to a central comparator mechanism that uses efference copy to attenuate the predictable component of sensory inputs arising from one's own actions in order to enhance the salience of external stimuli. To provide a quantitative measure of this attenuation, a force-matching task was developed in which subjects experience a force applied to their finger and are then required to match the perceived force by actively pushing on the finger using their other hand. The attenuation of predictable sensory input results in subjects producing a larger active force than was experienced passively. Here, we have examined the effects of a novel rTMS protocol, theta-burst stimulation (TBS), over primary motor cortex on this attenuation. TBS can alter the excitability of motor cortex to incoming activity. We show that application of a 20 s continuous train of TBS, that depresses motor cortex, significantly improves performance in a force-matching task. This suggests that the TBS intervention disturbed the predictive process that uses efference copy signals to attenuate predictable sensory input. A possible explanation for the effect is that TBS has a differential effect on the populations of neurones that generate motor output in M1 than on those neural structures that are involved in generating an efference copy of the motor command. PMID:17560617

  6. Generating Large Unit Staffs during Wartime Mobilization

    Science.gov (United States)

    2013-12-10

    Graham Cosmas, An Army for Empire: The United States Army in the Spanish-American War (Columbia, MO: University of Missouri Press, 1971), 195. 76 Ibid...100 Keast, The Procurement and Branch Distribution of Officers, 1. 101 Kent Greenfield, Robert Palmer, and Bell Wiley, The Army Ground Forces...A Gallant Little Army: The Mexico City Campaign, 84-85. 154 Graham Cosmas, An Army for Empire: The United States Army in the Spanish-American War

  7. Magnetar Bursts

    Science.gov (United States)

    Kouveliotou, Chryssa

    2014-01-01

    The Fermi/Gamma-ray Burst Monitor (GBM) was launched in June 2008. During the last five years the instrument has observed several hundreds of bursts from 8 confirmed magnetars and 19 events from unconfirmed sources. I will discuss the results of the GBM magnetar burst catalog, expand on the different properties of their diverse source population, and compare these results with the bursting activity of past sources. I will then conclude with thoughts of how these properties fit the magnetar theoretical models.

  8. Steam generator issues in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Strosnider, J.R. [NRC, Washington, DC (United States)

    1997-02-01

    Alloy 600 steam generator tubes in the US have exhibited degradation mechanisms similar to those observed in other countries. Effective programs have been implemented to address several degradation mechanisms including: wastage; mechanical wear; pitting; and fatigue. These degradation mechanisms are fairly well understood as indicated by the ability to effectively mitigate/manage them. Stress corrosion cracking (SCC) is the dominant degradation mechanism in the US. SCC poses significant inspection and management challenges to the industry and the regulators. The paper also addresses issues of research into SCC, inspection programs, plugging, repair strategies, water chemistry, and regulatory control. Emerging issues in the US include: parent tube cracking at sleeve joints; detection and repair of circumferential cracks; free span cracking; inspection and cracking of dented regions; and severe accident analysis.

  9. Thermomechanical Model and Bursting Tests to Evaluate the Risk of Swelling and Bursting of Modified 9Cr-1Mo Steel Steam Generator Tubes during a Sodium-Water Reaction Accident

    Directory of Open Access Journals (Sweden)

    C. Bertrand

    2014-01-01

    Full Text Available The MECTUB code was developed to evaluate the risk of swelling and bursting of Steam Generator (SG tubes. This code deals with the physic of intermediate steam-water leaks into sodium which induce a Sodium-Water Reaction (SWR. It is based on a one-dimensional calculation to describe the thermomechanical behavior of tubes under a high internal pressure and a fast external overheating. The mechanical model of MECTUB is strongly correlated with the kind of the material of the SG tubes. It has been developed and validated by using experiments performed on the alloy 800. A change to tubes made of Modified 9Cr-1Mo steel requires more knowledge of Modified 9Cr-1Mo steel behavior which influences the bursting time at high temperatures (up to 1200°C. Studies have been initiated to adapt the mechanical model and to qualify it for this material. The first part of this paper focuses on the mechanical law modelling (elasticity, plasticity, and creep for Modified 9Cr-1Mo steel and on overheating thermal data. In a second part, the results of bursting tests performed on Modified 9Cr-1Mo tubes in the SQUAT facility of CEA are used to validate the mechanical model of MECTUB for the Modified 9Cr-1Mo material.

  10. Only an early nitric oxide burst and the following wave of secondary nitric oxide generation enhanced effective defence responses of pelargonium to a necrotrophic pathogen.

    Science.gov (United States)

    Floryszak-Wieczorek, Jolanta; Arasimowicz, Magdalena; Milczarek, Grzegorz; Jelen, Henryk; Jackowiak, Hanna

    2007-01-01

    Participation of nitric oxide (NO) in cross-talk between ivy pelargonium (Pelargonium peltatum) leaves and Botrytis cinerea was investigated using electrochemical and biochemical approaches. In response to the necrotroph, leaves initiated a near-immediate NO burst, but the specificity of its generation was dependent on the genetic makeup of the host plant. In the resistant cultivar, a strong NO burst was followed by a wave of secondary NO generation, shown by bio-imaging with DAF-2DA. The epicentre of NO synthesis was located in targeted cells, which exhibited a TUNEL-positive reaction. Soon after the challenge, an elevated concentration of hydrogen peroxide (H(2)O(2)) was correlated with a reversible inhibition of catalase (CAT), ascorbate peroxidase (APX), and suppression of ethylene synthesis. The induced NO generation initially expanded and then gradually disappeared on successive days, provoking noncell-death-associated resistance with an enhanced pool of antioxidants, which finally favoured the maintenance of homeostasis of surrounding cells. By contrast, in the susceptible pelargonium, a weak NO burst was recorded and further NO generation increased only as the disease progressed, which was accompanied by very intensive H(2)O(2) and ethylene synthesis. The pathogen colonizing susceptible cells also acquired the ability to produce considerable amounts of NO and enhanced nitrosative and oxidative stress in host tissues.

  11. Generation unit selection via capital asset pricing model for generation planning

    Energy Technology Data Exchange (ETDEWEB)

    Romy Cahyadi; K. Jo Min; Chung-Hsiao Wang; Nick Abi-Samra [College of Engineering, Ames, IA (USA)

    2003-11-01

    The USA's electric power industry is undergoing substantial regulatory and organizational changes. Such changes introduce substantial financial risk in generation planning. In order to incorporate the financial risk into the capital investment decision process of generation planning, this paper develops and analyses a generation unit selection process via the capital asset pricing model (CAPM). In particular, utilizing realistic data on gas-fired, coal-fired, and wind power generation units, the authors show which and how concrete steps can be taken for generation planning purposes. It is hoped that the generation unit selection process will help utilities in the area of effective and efficient generation planning when financial risks are considered. 20 refs., 14 tabs.

  12. Generation unit selection via capital asset pricing model for generation planning

    Energy Technology Data Exchange (ETDEWEB)

    Cahyadi, Romy; Jo Min, K. [College of Engineering, Ames, IA (United States); Chunghsiao Wang [LG and E Energy Corp., Louisville, KY (United States); Abi-Samra, Nick [Electric Power Research Inst., Palo Alto, CA (United States)

    2003-07-01

    The electric power industry in many parts of U.S.A. is undergoing substantial regulatory and organizational changes. Such changes introduce substantial financial risk in generation planning. In order to incorporate the financial risk into the capital investment decision process of generation planning, in this paper, we develop and analyse a generation unit selection process via the capital asset pricing model (CAPM). In particular, utilizing realistic data on gas-fired, coal-fired, and wind power generation units, we show which and how concrete steps can be taken for generation planning purposes. It is hoped that the generation unit selection process developed in this paper will help utilities in the area of effective and efficient generation planning when financial risks are considered. (Author)

  13. Analysis on Operation Reliability of Generating Units in 2005

    Institute of Scientific and Technical Information of China (English)

    Zuo Xiaowen; Chu Xue

    2007-01-01

    @@ The weighted average equivalent availability factor of thermal power units in 2005 was 92.34%, an increase of 0.64 percentage points as compared to that in 2004. The average equivalent availability factor in 2005 was 92.22%, a decrease of 0.95 percentage points as compared to that in 2004. The nationwide operation reliability of generating units in 2005 was analyzed completely in this paper.

  14. Do Gamma-Ray Burst Sources Repeat?

    OpenAIRE

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb 1993; Wang and Lingenfelter 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al. 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and...

  15. Burst Suppression: A Review and New Insights

    Directory of Open Access Journals (Sweden)

    Jonathan Dillon Kenny

    2014-12-01

    Full Text Available Burst suppression is a pattern of brain electrical activity characterized by alternating periods of high-amplitude bursts and electrical silence. Burst suppression can arise from several different pathological conditions, as well as from general anesthesia. Here we review current algorithms that are used to quantify burst suppression, its various etiologies, and possible underlying mechanisms. We then review clinical applications of anesthetic-induced burst suppression. Finally, we report the results of our new study showing clear electrophysiological differences in burst suppression patterns induced by two common general anesthetics, sevoflurane and propofol. Our data suggest that the circuit mechanisms that generate burst suppression activity may differ between different general anesthetics.

  16. An Adaptive Multivariable Control System for Hydroelectric Generating Units

    Directory of Open Access Journals (Sweden)

    Gunne J. Hegglid

    1983-04-01

    Full Text Available This paper describes an adaptive multivariable control system for hydroelectric generating units. The system is based on a detailed mathematical model of the synchronous generator, the water turbine, the exiter system and turbine control servo. The models of the water penstock and the connected power system are static. These assumptions are not considered crucial. The system uses a Kalman filter for optimal estimation of the state variables and the parameters of the electric grid equivalent. The multivariable control law is computed from a Riccatti equation and is made adaptive to the generators running condition by means of a least square technique.

  17. Study on safety operation for large hydroelectric generator unit

    Science.gov (United States)

    Yan, Z. G.; Cui, T.; Zhou, L. J.; Zhi, F. L.; Wang, Z. W.

    2012-11-01

    Hydroelectric generator unit is a complex mechanical system which is composed of hydraulic turbine and electric generator. Rotary system is supported by the bearing bracket and the reinforced concrete structures, and vibration problem can't be avoided in the process of operating. Many large-scale hydroelectric units have been damaged because of the vibration problem in recent years. As the increase of the hydraulic turbine unit capacity and water head, the safe operation of hydraulic turbine has become a focus research in many countries. The operating characteristics of the hydraulic turbine have obvious differences at different working conditions. Based on the combination of field measurement and theoretical calculation, this paper shows a deep research on the safe operation of a large-scale Francis turbine unit. Firstly, the measurements of vibration, swing, pressure fluctuation and noise were carried out at 4 different heads. And also the relationships between vibrations and pressure fluctuations at different heads and working conditions were analysed deeply. Then the scientific prediction of safe operation for the unit at high head were done based on the CFD numerical calculation. Finally, this paper shows the division of the operating zone for the hydroelectric unit. According to the experimental results (vibrations, swings, pressure fluctuations and noise) as well as the theoretical results, the operating zone of the unit has been divided into three sections: prohibited operating zone, transition operating zone and safe operating zone. After this research was applied in the hydropower station, the security and economic efficiency of unit increased greatly, and enormous economic benefits and social benefits have been obtained.

  18. Generating unit maintenance scheduling under competitive market environments

    Energy Technology Data Exchange (ETDEWEB)

    Jin Ho Kim [Pusan National Univ. (Korea, Republic of). Dept. of Electrical and Communication Engineering; Jong Bae Park [Konkuk Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering; Jong Keun Park [Seoul National Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering; Yeung Han Chun [HongIlk Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering

    2005-03-01

    A novel approach to a generating unit maintenance scheduling problem in competitive electricity markets is presented in this paper. The objective is to develop a game-theoretic framework for analyzing strategic behaviors of generating companies (Gencos) from the standpoint of the generating unit maintenance scheduling (GMS) game and for obtaining the equilibrium solution for the GMS game. The GMS problem is formulated as a dynamic non-cooperative game with complete information. The players correspond to profit maximizing individual Gencos, and the payoff of each player is defined as the profits from the energy market. The optimal schedule is defined by Nash equilibrium (equilibriums) of the game. Numerical results for two-Genco system are used to demonstrate that the proposed framework can be successfully applied to analyzing the strategic behaviors of each Genco and to obtaining the corresponding Nash equilibrium. The result indicates that generating unit maintenance schedule is one of the major strategic behaviors whereby Genco maximize their profits in a competitive market environment. (author)

  19. Characterization of the Advanced Stirling Radioisotope Generator Engineering Unit 2

    Science.gov (United States)

    Lewandowski, Edward J.; Oriti, Salvatore M.; Schifer, Niholas A.

    2016-01-01

    Significant progress was made developing the Advanced Stirling Radioisotope Generator (ASRG) 140-W radioisotope power system. While the ASRG flight development project has ended, the hardware that was designed and built under the project is continuing to be tested to support future Stirling-based power system development. NASA Glenn Research Center recently completed the assembly of the ASRG Engineering Unit 2 (EU2). The ASRG EU2 consists of the first pair of Sunpower's Advanced Stirling Convertor E3 (ASC-E3) Stirling convertors mounted in an aluminum housing, and Lockheed Martin's Engineering Development Unit (EDU) 4 controller (a fourth-generation controller). The ASC-E3 convertors and Generator Housing Assembly (GHA) closely match the intended ASRG Qualification Unit flight design. A series of tests were conducted to characterize the EU2, its controller, and the convertors in the flight-like GHA. The GHA contained an argon cover gas for these tests. The tests included measurement of convertor, controller, and generator performance and efficiency; quantification of control authority of the controller; disturbance force measurement with varying piston phase and piston amplitude; and measurement of the effect of spacecraft direct current (DC) bus voltage on EU2 performance. The results of these tests are discussed and summarized, providing a basic understanding of EU2 characteristics and the performance and capability of the EDU 4 controller.

  20. UNIT 14A.4 Generation of Recombinant Vaccinia Viruses

    Science.gov (United States)

    Earl, Patricia L.; Moss, Bernard; Wyatt, Linda S.

    2016-01-01

    This unit describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector or PCR fragment to generate a recombinant virus. Selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses are described. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented. This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector or PCR fragment to generate a recombinant virus (see Basic Protocol 1). Also presented are selection and screening methods used to isolate recombinant viruses (see Basic Protocol 2) and a method for the amplification of recombinant viruses (see Basic Protocol 3). Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented (see Basic Protocol 4). HeLa S3 cells are recommended for large-scale growth of vaccinia virus. BS-C-1 cells may be used for xanthine-guanine phosphoribosyltransferase (XGPRT) and plaque size selection, fluorescent protein screening, transfection and determination of virus titer (UNIT 14A.3). For thymidine kinase (TK) selection, HuTK− 143B cells are used. With MVA, all steps are carried out in CEF or BHK-21 cells (UNIT 14A.3). CAUTION Proceed carefully and follow biosafety level 2 (BL-2) practices when working with standard vaccinia virus (see UNIT 14A.3 for safety precautions). [*Copy Editor: The original CPMB unit referenced CPMB Unit 16.15 for safety. The chapter editor asked that the authors include some of the safety information in the revised units – CPMB 16.16 and 16.17 – which are now CPMC Unit 14A.3 and 14A.4. As a result, the authors changed the safety citation here to “Unit 14A.3”, which doesn’t have nearly as much information as the original CPMB Unit 16.15. Perhaps the

  1. Fluorescent lamp unit with magnetic field generating means

    Science.gov (United States)

    Grossman, M.W.; George, W.A.

    1989-08-08

    A fluorescent lamp unit having a magnetic field generating means for improving the performance of the fluorescent lamp is disclosed. In a preferred embodiment the fluorescent lamp comprises four longitudinally extending leg portions disposed in substantially quadrangular columnar array and joined by three generally U-shaped portions disposed in different planes. In another embodiment of the invention the magnetic field generating means comprises a plurality of permanent magnets secured together to form a single columnar structure disposed within a centrally located region defined by the shape of lamp envelope. 4 figs.

  2. Single-unit pattern generators for quadruped locomotion

    DEFF Research Database (Denmark)

    Morse, Gregory; Risi, Sebastian; Snyder, Charles R;

    2013-01-01

    locomotion can generate oscillations through popular techniques such as continuous time recurrent neural networks (CTRNNs) or sinusoidal input, they typically face a challenge in maintaining long-term stability. The aim of this paper is to address this challenge by introducing an effective alternative based...... on a new type of neuron called a single-unit pattern generator (SUPG). The SUPG, which is indirectly encoded by a compositional pattern producing network (CPPN) evolved by HyperNEAT, produces a flexible temporal activation pattern that can be reset and repeated at any time through an explicit trigger input...

  3. Infinitesimal generators and quasi-units in potential theory.

    Science.gov (United States)

    Arsove, M; Leutwiler, H

    1975-07-01

    The underlying structure is taken as a strongly superharmonic cone [unk], defined as a partially ordered abelian semigroup with identity 0 which admits a multiplication by nonnegative scalars and satisfies two fundamental axioms of a potentialtheoretic character. In terms of a fixed nonzero element e there is introduced on [unk] a one-parameter family of nonlinear operators S(lambda) (lambda >/= 0) closely connected with the abstract theory of quasibounded and singular elements. The semigroup {S(lambda)} admits an infinitesimal generator A, and the elements invariant under A, called quasi-units, generalize the Yosida quasi-units in the theory of Riesz spaces. Quasi-units in [unk] are studied, both from a potentialtheoretic and a function-alanalytic viewpoint, culminating in a spectral representation theorem for quasi-bounded elements which extends the classical Freudenthal spectral theorem of Riesz space theory.

  4. 76 FR 32237 - Florida Power Corporation, Crystal River Unit 3 Nuclear Generating Plant; Notice of Availability...

    Science.gov (United States)

    2011-06-03

    ... COMMISSION Florida Power Corporation, Crystal River Unit 3 Nuclear Generating Plant; Notice of Availability... Plants and Public Meetings for the License Renewal of Crystal River Unit 3 Nuclear Generating Plant... operation for Crystal River Unit 3 Nuclear Generating Plant. Crystal River Unit 3 Nuclear Generating Plant...

  5. QUALITY EVALUATION OF THE TPP POWER GENERATING UNITS WEAR RECONDITIONING

    Directory of Open Access Journals (Sweden)

    E. M. Farhadzadeh

    2016-01-01

    Full Text Available Reconditioning of the power generating unit worn equipment and devices is conducted during the scheduled repair period. Quality of wear reconditioning is evaluated by technical state and repair work implementation. Quality of the repair work execution characterizes logistical activities of the power station and the repair services and is rated by a five-grade scale. There are three technical conditions: adequate, subject to reservations, falling short of the technical standard documentation requirements. In practical work these constraints give place to essential ambiguity of the decision. Further to regulating techniques by way of informational support, the authors propose conducting the wear-reconditioning quality evaluation (repair quality accordingly the technical-and-economic indexes pattern of change. The paper recommends applying similarly the fivegrade system in evaluating the power generating unit technical state and distinguishes intolerable, dissatisfactory, fair, good and model estimates. The study demonstrates the assessment criteria dependence on the character of reliability and economical efficiency of performance variation after the repair with increase or decrease of the technical-and-economic indexes in reference to their mean, minimum and maximum values before the repair. The cases ascribed to intolerable quality of the wear reconditioning are those with one or more technical-and-economic indexes that not only failed to improve their values but deteriorated, and at that they became the worst amongst observable values. The model quality estimate of the wear reconditioning is allotted under condition that the power unit technical-and-economic index valuations after the repair not merely improved but also exceeded the best among those under observation. The developed method and algorithm for quality evaluation of the scheduled repair implementation contribute to practical realization of the independent monitoring. This monitoring

  6. Loss Allocation in a Distribution System with Distributed Generation Units

    DEFF Research Database (Denmark)

    Lund, Torsten; Nielsen, Arne Hejde; Sørensen, Poul Ejnar

    2007-01-01

    In Denmark, a large part of the electricity is produced by wind turbines and combined heat and power plants (CHPs). Most of them are connected to the network through distribution systems. This paper presents a new algorithm for allocation of the losses in a distribution system with distributed...... generation. The algorithm is based on a reduced impedance matrix of the network and current injections from loads and production units. With the algorithm, the effect of the covariance between production and consumption can be evaluated. To verify the theoretical results, a model of the distribution system...

  7. BURSTING FAULT ANALYSIS OF PRESSURE GAUGE DASH UNIT%冷媒表阀组视窗爆裂事故分析

    Institute of Scientific and Technical Information of China (English)

    李东晖

    2013-01-01

      冷媒表阀组的视窗玻璃在进行空调维修的过程中发生爆裂,经过对事故中冷媒表阀组的宏观检查、示值试验、断口扫描电镜与能谱分析,发现维修人员超压处理措施不当是造成事故的主因。%  When the air conditioning was being repaired, The glass of the pressure gauge dash unit bursted. The fault analysis included macroanalysis, pressure test, fracture analysis and energy spectrum analysis. The maintenance man took the wrong measures to reduce the system pressure was the prime reason of this accident.

  8. Measures of coherence-generating power for quantum unital operations

    Science.gov (United States)

    Zanardi, Paolo; Styliaris, Georgios; Campos Venuti, Lorenzo

    2017-05-01

    Given an orthonormal basis B in a d -dimensional Hilbert space and a unital quantum operation E acting on it, one can define a nonlinear mapping that associates with E a d ×d real-valued matrix that we call the coherence matrix of E with respect to B . This is the Gram matrix of the coherent part of the basis projections of B under E . We show that one can use this coherence matrix to define vast families of measures of the coherence-generating power (CGP) of the operation. These measures have a natural geometrical interpretation as separation of E from the set of incoherent unital operations. The probabilistic approach to CGP discussed in P. Zanardi et al. [Phys. Rev. A 95, 052306 (2017)., 10.1103/PhysRevA.95.052306] can be reformulated and generalized, introducing, alongside the coherence matrix, another d ×d real-valued matrix, the simplex correlation matrix. This matrix describes the relevant statistical correlations in the input ensemble of incoherent states. Contracting these two matrices, one finds CGP measures associated with the process of preparing the given incoherent ensemble and processing it with the chosen unital operation. Finally, in the unitary case, we discuss how these concepts can be made compatible with an underlying tensor product structure by defining families of CGP measures that are additive.

  9. Effective results for unit equations over finitely generated domains

    CERN Document Server

    Evertse, Jan-Hendrik

    2011-01-01

    Let A be a commutative domain containing Z which is finitely generated as a Z-algebra, and let a,b,c be non-zero elements of A. It follows from work of Siegel, Mahler, Parry and Lang that the equation (*) ax+by=c has only finitely many solutions in elements x,y of the unit group A* of A, but the proof following from their arguments is ineffective. Using linear forms in logarithms estimates of Baker and Coates, in 1979 Gy\\H{o}ry gave an effective proof of this finiteness result, in the special case that A is the ring of S-integers of an algebraic number field. Some years later, Gy\\H{o}ry extended this to a restricted class of finitely generated domains A, containing transcendental elements. In the present paper, we give an effective finiteness proof for the number of solutions of (*) for arbitrary domains A finitely generated over Z. In fact, we give an explicit upper bound for the `sizes' of the solutions x,y, in terms of defining parameters for A,a,b,c. In our proof, we use already existing effective finiten...

  10. Spindle Bursts in Neonatal Rat Cerebral Cortex

    Directory of Open Access Journals (Sweden)

    Jenq-Wei Yang

    2016-01-01

    Full Text Available Spontaneous and sensory evoked spindle bursts represent a functional hallmark of the developing cerebral cortex in vitro and in vivo. They have been observed in various neocortical areas of numerous species, including newborn rodents and preterm human infants. Spindle bursts are generated in complex neocortical-subcortical circuits involving in many cases the participation of motor brain regions. Together with early gamma oscillations, spindle bursts synchronize the activity of a local neuronal network organized in a cortical column. Disturbances in spindle burst activity during corticogenesis may contribute to disorders in cortical architecture and in the activity-dependent control of programmed cell death. In this review we discuss (i the functional properties of spindle bursts, (ii the mechanisms underlying their generation, (iii the synchronous patterns and cortical networks associated with spindle bursts, and (iv the physiological and pathophysiological role of spindle bursts during early cortical development.

  11. Spindle Bursts in Neonatal Rat Cerebral Cortex.

    Science.gov (United States)

    Yang, Jenq-Wei; Reyes-Puerta, Vicente; Kilb, Werner; Luhmann, Heiko J

    2016-01-01

    Spontaneous and sensory evoked spindle bursts represent a functional hallmark of the developing cerebral cortex in vitro and in vivo. They have been observed in various neocortical areas of numerous species, including newborn rodents and preterm human infants. Spindle bursts are generated in complex neocortical-subcortical circuits involving in many cases the participation of motor brain regions. Together with early gamma oscillations, spindle bursts synchronize the activity of a local neuronal network organized in a cortical column. Disturbances in spindle burst activity during corticogenesis may contribute to disorders in cortical architecture and in the activity-dependent control of programmed cell death. In this review we discuss (i) the functional properties of spindle bursts, (ii) the mechanisms underlying their generation, (iii) the synchronous patterns and cortical networks associated with spindle bursts, and (iv) the physiological and pathophysiological role of spindle bursts during early cortical development.

  12. Evolving Distributed Generation Support Mechanisms: Case Studies from United States, Germany, United Kingdom, and Australia

    Energy Technology Data Exchange (ETDEWEB)

    Lowder, Travis [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhou, Ella [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tian, Tian [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-03-14

    This report expands on a previous National Renewable Energy Laboratory (NREL) technical report (Lowder et al. 2015) that focused on the United States' unique approach to distributed generation photovoltaics (DGPV) support policies and business models. While the focus of that report was largely historical (i.e., detailing the policies and market developments that led to the growth of DGPV in the United States), this report looks forward, narrating recent changes to laws and regulations as well as the ongoing dialogues over how to incorporate distributed generation (DG) resources onto the electric grid. This report also broadens the scope of Lowder et al. (2015) to include additional countries and technologies. DGPV and storage are the principal technologies under consideration (owing to market readiness and deployment volumes), but the report also contemplates any generation resource that is (1) on the customer side of the meter, (2) used to, at least partly, offset a host's energy consumption, and/or (3) potentially available to provide grid support (e.g., through peak shaving and load shifting, ancillary services, and other means).

  13. A Scientific Trigger Unit for Space-Based Real-Time Gamma Ray Burst Detection, II - Data Processing Model and Benchmarks

    CERN Document Server

    Provost, Hervé Le; Flouzat, Christophe; Kestener, Pierre; Chaminade, Thomas; Donati, Modeste; Château, Frédéric; Daly, François; Fontignie, Jean

    2014-01-01

    The Scientific Trigger Unit (UTS) is a satellite equipment designed to detect Gamma Ray Bursts (GRBs) observed by the onboard 6400 pixels camera ECLAIRs. It is foreseen to equip the low-Earth orbit French-Chinese satellite SVOM and acts as the GRB trigger unit for the mission. The UTS analyses in real-time and in great details the onboard camera data in order to select the GRBs, to trigger a spacecraft slew re-centering each GRB for the narrow field-of-view instruments, and to alert the ground telescope network for GRB follow-up observations. A few GRBs per week are expected to be observed by the camera; the UTS targets a close to 100% trigger efficiency, while being selective enough to avoid fake alerts. This is achieved by running the complex scientific algorithms on a radiation tolerant hardware, based on a FPGA data pre-processor and a CPU with a Real-Time Operating System. The UTS is a scientific software, firmware and hardware co-development. A Data Processing Model (DPM) has been developed to fully val...

  14. A key role for the caudoventral pontine tegmentum in the simultaneous generation of eye saccades in bursts and associated ponto-geniculo-occipital waves during paradoxical sleep in the cat.

    Science.gov (United States)

    Vanni-Mercier, G; Debilly, G

    1998-09-01

    frequency (number/min) of eye saccades in bursts directed contralaterally to the side of the injection (by 48-54%) and reduced the velocity of these saccades to that of isolated eye saccades. Atropine also significantly reduced the frequency (by 60%) of all types of bursts of ponto-geniculo-occipital waves, with a maximal effect (80% reduction) on long bursts of ponto-geniculo-occipital waves, while it increased the frequency of isolated ponto-geniculo-occipital waves. However, atropine did not change the value of intra-burst intervals. These findings support the hypothesis that eye saccades in bursts and associated ponto-geniculo-occipital waves are generated as a whole by a common structure and that this structure is at least partly defined by the caudoventral pontine tegmentum.

  15. AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XIV, UNDERSTANDING DC GENERATOR PRINCIPLES.

    Science.gov (United States)

    Human Engineering Inst., Cleveland, OH.

    THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATING PRINCIPLES OF DIRECT CURRENT GENERATORS USED ON DIESEL POWERED EQUIPMENT. TOPICS ARE (1) WHAT IS A GENERATOR AND ITS USE, (2) SHUNT GENERATOR PRINCIPLES, (3) POWER AND RATINGS OF A GENERATOR, (4) ARMATURE REACTION, (5) WHAT IS POLARITY, (6) TWO GENERATOR…

  16. Disinhibition Bursting of Dopaminergic Neurons

    Directory of Open Access Journals (Sweden)

    Collin J Lobb

    2011-05-01

    Full Text Available Substantia nigra pars compacta (SNpc dopaminergic neurons receive strong tonic inputs from GABAergic neurons in the substantia nigra pars reticulata (SNpr and globus pallidus (GP, and glutamatergic neurons in the subthalamic nucleus. The presence of these tonic inputs raises the possibility that phasic disinhibition may trigger phasic bursts in dopaminergic neurons. We first applied constant NMDA and GABAA conductances onto a two-compartment single cell model of the dopaminergic neuron (Kuznetsov et al., 2006. The model exhibited disinhibition bursting upon stepwise removal of inhibition. A further bifurcation analysis suggests that disinhibition may be more robust than excitation alone in that for most levels of NMDA conductance, the cell remains capable of bursting even after a complete removal of inhibition, whereas too much excitatory input will drive the cell into depolarization block. To investigate the network dynamics of disinhibition, we used a modified version of an integrate-and-fire based model of the basal ganglia (Humphries et al., 2006. Synaptic activity generated in the network was delivered to the two-compartment single cell dopaminergic neuron. Phasic activation of the D1-expressing medium spiny neurons in the striatum (D1STR produced disinhibition bursts in dopaminergic neurons through the direct pathway (D1STR to SNpr to SNpc. Anatomical studies have shown that D1STR neurons have collaterals that terminate in GP. Adding these collaterals to the model, we found that striatal activation increased the intra-burst firing frequency of the disinhibition burst as the weight of this connection was increased. Our studies suggest that striatal activation is a robust means by which disinhibition bursts can be generated by SNpc dopaminergic neurons, and that recruitment of the indirect pathway via collaterals may enhance disinhibition bursting.

  17. The Double Firing Burst

    Science.gov (United States)

    2008-09-01

    Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth. Uncovering the disc ESO PR Photo 28/08 A Gamma-Ray Burst with Two Jets Read more on this illuminating blast in the additional story. GRB 080319B was so intense that, despite happening halfway across the Universe, it could have been seen briefly with the unaided eye (ESO 08/08). In a paper to appear in the 11 September issue of Nature, Judith Racusin of Penn State University, Pennsylvania (USA), and a team of 92 co-authors report observations across the electromagnetic spectrum that began 30 minutes before the explosion and followed it for months afterwards. "We conclude that the burst's extraordinary brightness arose from a jet that shot material almost directly towards Earth at almost the speed of light - the difference is only 1 part in 20 000," says Guido Chincarini, a member of the team. Gamma-ray bursts are the Universe's most luminous explosions. Most occur when massive stars run out of fuel. As a star collapses, it creates a black hole or neutron star that, through processes not fully understood, drives powerful gas jets outward. As the jets shoot into space, they strike gas previously shed by the star and heat it, thereby generating bright afterglows. The team believes the jet directed toward Earth contained an ultra-fast component just 0.4 degrees across (this is slightly smaller than the apparent size of the Full Moon). This jet is contained within another slightly less energetic jet about 20 times wider. The broad component is more typical of other bursts. "Perhaps every gamma-ray burst has a narrow jet, but astronomers miss it most of the time," says team member Stefano Covino. "We happened to view this monster down the barrel of the very narrow and energetic jet, and the chance for

  18. A next generation Ultra-Fast Flash Observatory (UFFO-100) for IR/optical observations of the rise phase of gamma-ray bursts

    CERN Document Server

    Grossan, B; Ahmad, S; Ahn, K B; Barrillon, P; Brandt, S; Budtz-Jørgensen, C; Castro-Tirado, A J; Chen, P; Choi, H S; Choi, Y J; Connell, P; Dagoret-Campagne, S; De La Taille, C; Eyles, C; Hermann, I; Huang, M –H A; Jung, A; Jeong, S; Kim, J E; Kim, M; Kim, S -W; Kim, Y W; Lee, J; Lim, H; Linder, E V; Liu, T –C; Lund, N; Min, K W; Na, G W; Nam, J W; Panasyuk, M I; Ripa, J; Reglero, V; Rodrigo, J M; Smoot, G F; Suh, J E; Svertilov, S; Vedenkin, N; Wang, M –Z; Yashin, I; Zhao, M H

    2012-01-01

    The Swift Gamma-ray Burst (GRB) observatory responds to GRB triggers with optical observations in ~ 100 s, but cannot respond faster than ~ 60 s. While some ground-based telescopes respond quickly, the number of sub-60 s detections remains small. In 2013 June, the Ultra-Fast Flash Observatory-Pathfinder is to be launched on the Lomonosov spacecraft to investigate early optical GRB emission. This pathfinder mission is necessarily limited in sensitivity and event rate; here we discuss a next generation rapid-response space observatory. We list science topics motivating our instruments, those that require rapid optical-IR GRB response, including: A survey of GRB rise shapes/times, measurements of optical bulk Lorentz factors, investigation of magnetic dominated (vs. non-magnetic) jet models, internal vs. external shock origin of prompt optical emission, the use of GRBs for cosmology, and dust evaporation in the GRB environment. We also address the impacts of the characteristics of GRB observing on our instrument...

  19. 78 FR 285 - Supplemental Final Environmental Impact Statement for Healy Power Generation Unit #2, Healy, AK

    Science.gov (United States)

    2013-01-03

    ..., now known as Healy Unit 1. Healy Unit 1 is a 25 megawatt (MW) coal-fired boiler that has been owned...- fired steam generator owned by AIDEA, which underwent test operation for two years as part of...

  20. Gamma: A C++ Sound Synthesis Library Further Abstracting the Unit Generator

    DEFF Research Database (Denmark)

    Putnam, Lance Jonathan

    2014-01-01

    Gamma is a C++ library for sound synthesis that was created to address some of the limitations of existing sound synthesis libraries. The first limitation is that unit generators cannot easily be organized into separate sampling domains. This makes it difficult to use unit generators with differe....... Gamma makes explicit two novel abstractions---assignable sampling domains and algorithm Strategies---to help overcome these limitations and extend the application range of its unit generators....

  1. Generation of Nonlinear Electric Field Bursts in the Outer Radiation Belt through Electrons Trapping by Oblique Whistler Waves

    Science.gov (United States)

    Agapitov, Oleksiy; Drake, James; Mozer, Forrest

    2016-04-01

    Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. The parameters favorable for the generation of TDS were studied experimentally as well as making use of 2-D particle-in-cell (PIC) simulations for the system with inhomogeneous magnetic field. It is shown that an outward propagating front of whistlers and hot electrons amplifies oblique whistlers which collapse into regions of intense parallel electric field with properties consistent with recent observations of TDS from the Van Allen Probe satellites. Oblique whistlers seed the parallel electric fields that are driven by the beams. The resulting parallel electric fields trap and heat the precipitating electrons. These electrons drive spikes of intense parallel electric field with characteristics similar to the TDSs seen in the VAP data. The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system. These effects are observed by the Van Allen Probes in the radiation belts. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.

  2. A next generation Ultra-Fast Flash Observatory (UFFO-100) for IR/optical observations of the rise phase of gamma-ray bursts

    Science.gov (United States)

    Grossan, B.; Park, I. H.; Ahmad, S.; Ahn, K. B.; Barrillon, P.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Chen, P.; Choi, H. S.; Choi, Y. J.; Connell, P.; Dagoret-Campagne, S.; De La Taille, C.; Eyles, C.; Hermann, I.; Huang, M.-H. A.; Jung, A.; Jeong, S.; Kim, J. E.; Kim, M.; Kim, S.-W.; Kim, Y. W.; Lee, J.; Lim, H.; Linder, E. V.; Liu, T.-C.; Lund, N.; Min, K. W.; Na, G. W.; Nam, J. W.; Panasyuk, M. I.; Ripa, J.; Reglero, V.; Rodrigo, J. M.; Smoot, G. F.; Suh, J. E.; Svertilov, S.; Vedenkin, N.; Wang, M.-Z.; Yashin, I.; Zhao, M. H.

    2012-09-01

    The Swift Gamma-ray Burst (GRB) observatory responds to GRB triggers with optical observations in ~ 100 s, butcannot respond faster than ~ 60 s. While some rapid-response ground-based telescopes have responded quickly, thenumber of sub-60 s detections remains small. In 2013 June, the Ultra-Fast Flash Observatory-Pathfinder is expected tobe launched on the Lomonosov spacecraft to investigate early optical GRB emission. Though possessing uniquecapability for optical rapid-response, this pathfinder mission is necessarily limited in sensitivity and event rate; here wediscuss the next generation of rapid-response space observatory instruments. We list science topics motivating ourinstruments, those that require rapid optical-IR GRB response, including: A survey of GRB rise shapes/times,measurements of optical bulk Lorentz factors, investigation of magnetic dominated (vs. non-magnetic) jet models,internal vs. external shock origin of prompt optical emission, the use of GRBs for cosmology, and dust evaporation inthe GRB environment. We also address the impacts of the characteristics of GRB observing on our instrument andobservatory design. We describe our instrument designs and choices for a next generation space observatory as a secondinstrument on a low-earth orbit spacecraft, with a 120 kg instrument mass budget. Restricted to relatively modest mass,power, and launch resources, we find that a coded mask X-ray camera with 1024 cm2 of detector area could rapidlylocate about 64 GRB triggers/year. Responding to the locations from the X-ray camera, a 30 cm aperture telescope witha beam-steering system for rapid (~ 1 s) response and a near-IR camera should detect ~ 29 GRB, given Swift GRBproperties. The additional optical camera would permit the measurement of a broadband optical-IR slope, allowingbetter characterization of the emission, and dynamic measurement of dust extinction at the source, for the first time.

  3. Interleukin-10 inhibits burst-forming unit-erythroid growth by suppression of endogenous granulocyte-macrophage colony-stimulating factor production from T cells.

    Science.gov (United States)

    Oehler, L; Kollars, M; Bohle, B; Berer, A; Reiter, E; Lechner, K; Geissler, K

    1999-02-01

    Numerous cytokines released from accessory cells have been shown to exert either stimulatory or inhibitory growth signals on burst-forming unit-erythroid (BFU-E) growth. Because of its cytokine synthesis-inhibiting effects on T cells and monocytes, interleukin-10 (IL-10) may be a potential candidate for indirectly affecting erythropoiesis. We investigated the effects of IL-10 on BFU-E growth from normal human peripheral blood mononuclear cells (PBMC) using a clonogenic progenitor cell assay. The addition of recombinant human IL-10 to cultures containing recombinant human erythropoietin suppressed BFU-E growth in a dose-dependent manner (by 55.2%, range 47.3-63.3%, p cultivating highly enriched CD34+ cells. BFU-E growth from PBMC also was markedly suppressed in the presence of a neutralizing anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody (by 48.7%, range 32.9-61.2% inhibition,p < 0.01), but not by neutralizing antibodies against granulocyte colony-stimulating factor and interleukin-3. This suggests a stimulatory role of endogenously released GM-CSF on BFU-E formation. Also, the addition of exogenous GM-CSF completely restored IL-10-induced suppression of BFU-E growth. To determine the cellular source of GM-CSF production, we analyzed GM-CSF levels in suspension cultures containing PBMC that were either depleted of monocytes or T cells. Monocyte-depleted PBMC showed spontaneous production of increasing amounts of GM-CSF on days 3, 5, and 7, respectively, which could be suppressed by IL-10, whereas GM-CSF levels did not increase in cultures containing T-cell-depleted PBMC. Our data indicate that IL-10 inhibits the growth of erythroid progenitor cells in vitro, most likely by suppression of endogenous GM-CSF production from T cells.

  4. k-space drift due to the density variation as a cause of electromagnetic emission generation of type III solar radio bursts by a non-gyrotropic electron beam

    Science.gov (United States)

    Tsiklauri, David; Schmitz, Holger

    2013-04-01

    It is widely accepted that there is a correlation between super-thermal electron beams and type III solar radio bursts. Whilst the correlation is an established fact, the actual mechanism that generates the type III burst emission is not yet fully determined. The main source of the uncertainty is current inability to send in-situ probes at distances 0.15 - 1.5Rsun from the solar surface (photosphere). The most widely accepted mechanism, that historically appeared first is the plasma emission. In plasma emission mechanism quasilinear theory, kinetic Fokker-Planck type equation for describing the dynamics of an electron beam is used, in conjunction with the spectral energy density evolutionary equations for Langmuir and ion-sound waves. Further, non-linear wave-wave interactions between Langmuir, ion-acoustic and EM waves produce emission at electron plasma frequency, ?pe or the second harmonic, 2?pe. A variant of the plasma emission mechanism is the stochastic growth theory, where density irregularities produce a random growth, in such a way that Langmuir waves are generated stochastically and quasilinear interactions within the Langmuir clumps cause the beam to fluctuate about marginal stability. The latter models have been used for producing the solar type III burst observable parameters. Other possible mechanisms include: linear mode conversion, antenna radiation and non-gyrotropic electron beam emission [1]. Recent works [2,3] elucidated further the non-gyrotropic electron beam emission, first proposed in Ref.[1]. In particular, the effect of electron beam pitch angle and density gradient on solar type III radio bursts was studied [2] and the role of electron cyclotron maser (ECM) emission with a possible mode coupling to the z-mode was explored [3]. In this contribution and paper [4], using large-scale Particle-In-Cell simulations, we explore the non-gyrotropic electron beam emission mechanism by studying the effects of electron beam kinetics and k-space drift

  5. 78 FR 16302 - Crystal River Unit 3 Nuclear Generating Plant, Application for Amendment to Facility Operating...

    Science.gov (United States)

    2013-03-14

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Crystal River Unit 3 Nuclear Generating Plant, Application for Amendment to Facility Operating... Operating License No. DPR-72 for the Crystal River Unit 3 Nuclear Generating Plant (CR-3), located in...

  6. 76 FR 53972 - Florida Power Corporation, Crystal River Unit No. 3 Nuclear Generating Plant; Notice of...

    Science.gov (United States)

    2011-08-30

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Florida Power Corporation, Crystal River Unit No. 3 Nuclear Generating Plant; Notice of... Facility Operating License No. DPR-72 for Crystal River Unit 3 Nuclear generating Plant (CR-3), currently...

  7. Gamma: A C++ Sound Synthesis Library Further Abstracting the Unit Generator

    DEFF Research Database (Denmark)

    Putnam, Lance Jonathan

    2014-01-01

    sample rates and in other domains, namely the frequency domain. The second limitation is that certain internal unit generator algorithms, such as interpolation, cannot be customized. This tends to lead to closed architectures consisting of multiple unit generators with only slight algorithmic differences......Gamma is a C++ library for sound synthesis that was created to address some of the limitations of existing sound synthesis libraries. The first limitation is that unit generators cannot easily be organized into separate sampling domains. This makes it difficult to use unit generators with different....... Gamma makes explicit two novel abstractions---assignable sampling domains and algorithm Strategies---to help overcome these limitations and extend the application range of its unit generators....

  8. Grey extra-deleting theory-based governor control for hydro-generator unit

    Directory of Open Access Journals (Sweden)

    Ming-dong Wang

    2015-10-01

    Full Text Available The control effect by using the conventional method is not satisfied because of the grey character caused from time-variant parameters of hydro-generator units and its governor. The grey extra-deleting control theory is applied to the governor design of hydro-generator units in this paper. After the mathematic model of hydro-generator and its governor are founded, the grey extra-deleting controller is designed and its effect is studied compared with the conventional proportional–integral–derivative governor. The simulation results indicate that the grey extra-deleting controller can improve dynamic characteristic of hydro-generator units.

  9. A New Generation of Visible-Light Curing Units

    Science.gov (United States)

    1988-12-01

    OP50 , OPI01, OP300, OP400) Danbury...6.0 x 5.875 6.00 Yes 5. OP50 1.875 x 3.0 x 4.25 3.25 No 6. OP101 2.0 x 4.250 x 3.00 3.00 No 7. OP300 2.0 x 6.875 x 4.25 4.30 No 8. OP400 5.0 x 6.25 x...Unit to wand cord length 1. Trans 8𔃺" 7𔃺" 2. Visi 610" 710" 3. Helio 6𔄀" 5󈧷 4. Pris 7𔄃" 6𔄁" 5. OP50 919" 6󈧭 6. OP101 5𔄁" 5𔃺 7. OP300 5𔄂"

  10. Bright 30 THz Impulsive Solar Bursts

    CERN Document Server

    Kaufmann, P; Marcon, R; Kudaka, A S; Cabezas, D P; Cassiano, M M; Francile, C; Fernandes, L O T; Ramirez, R F Hidalgo; Luoni, M; Marun, A; Pereyra, P; de Souza, R V

    2015-01-01

    Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept. The most intense burst was observed together with a GOES X2 class event on October 27, 2014, also detected at two sub-THz frequencies, RHESSI X-rays and SDO/HMI and EUV. It exhibits strikingly good correlation in time and in space with white light flare emission. It is likely that this association may prove to be very common. All three 30 THz events recently observed exhibited intense fluxes in the range of 104 solar flux units, considerably larger than those measured for the same events at microwave and sub-mm wavelengths. The 30 THz burst emission might be part of the same spectral burst component found at sub-THz frequencies. The 30 THz solar bursts open a promising new window for the study of flares at their origin

  11. Column Generation for Transmission Switching of Electricity Networks with Unit Commitment

    DEFF Research Database (Denmark)

    Villumsen, Jonas Christoffer; Philpott, Andy B.

    2011-01-01

    This paper presents the problem of finding the minimum cost dispatch and commitment of power generation units in a transmission network with active switching.We use the term active switching to denote the use of switches to optimize network topology in an operational context. We propose a Dantzig......-Wolfe reformulation and a novel column generation framework to solve the problem efficiently. Preliminary results are presented for the IEEE-118 bus network with 19 generator units. Active switching is shown to reduce total cost by up to 15 % for a particular 24-hour period. Furthermore, the need for generator...

  12. ACO-Initialized Wavelet Neural Network for Vibration Fault Diagnosis of Hydroturbine Generating Unit

    Directory of Open Access Journals (Sweden)

    Zhihuai Xiao

    2015-01-01

    Full Text Available Considering the drawbacks of traditional wavelet neural network, such as low convergence speed and high sensitivity to initial parameters, an ant colony optimization- (ACO- initialized wavelet neural network is proposed in this paper for vibration fault diagnosis of a hydroturbine generating unit. In this method, parameters of the wavelet neural network are initialized by the ACO algorithm, and then the wavelet neural network is trained by the gradient descent algorithm. Amplitudes of the frequency components of the hydroturbine generating unit vibration signals are used as feature vectors for wavelet neural network training to realize mapping relationship from vibration features to fault types. A real vibration fault diagnosis case result of a hydroturbine generating unit shows that the proposed method has faster convergence speed and stronger generalization ability than the traditional wavelet neural network and ACO wavelet neural network. Thus it can provide an effective solution for online vibration fault diagnosis of a hydroturbine generating unit.

  13. ASP - Grid connections of large power generating units; ASP - Anslutning av stoerre produktionsanlaeggningar till elnaetet

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Aake; Larsson, Richard [Vattenfall Power Consultants, Stockholm (Sweden)

    2006-12-15

    Grid connections of large power generating units normally require more detailed studies compared to small single units. The required R and D-level depends on the specific characteristics of the production units and the connecting grid. An inquiry for a grid connection will raise questions for the grid owner regarding transmission capability, losses, fault currents, relay protection, dynamic stability etc. Then only a few larger wind farms have been built, the experiences from these types of grid connections are limited and for that reason it can be difficult to identify issues appropriate for further studies. To ensure that electric power generating units do not have unacceptable impact on the grid, directions from the Swedish TSO (Svenska Kraftnaet) have been stated. The directions deal, for example, with power generation in specific ranges of voltage level and frequency and the possibility to remain connected to the grid when different faults occur. The requirements and the consequences of these directions are illustrated. There are three main issues that should be considered: Influence on the power flow from generating units regarding voltage level, currents, losses etc.; Different types of electric systems in generating units contribute to different levels of fault currents. For that reason the resulting fault current levels have to be studied; It is required that generating units should remain connected to the grid at different modes of operation and faults. These modes have to be verified. Load flow and dynamic studies normally demand computer models. Comprehensive models, for instance of wind farms, can bee difficult to design and normally large computer capacity is required. Therefore simplified methods to perform relevant studies are described. How to model an electric power generating unit regarding fault currents and dynamic stability is described. An inquiry for a grid connection normally brings about a discussion concerning administration. To make it

  14. Stochastic Electric Power Generation Unit Commitment in Deregulated Power Market Environment

    Directory of Open Access Journals (Sweden)

    F. Gharehdaghi

    2012-03-01

    Full Text Available Utilities participating in deregulated markets observe increasing uncertainty in load (i.e., demand for electric power and prices for fuel and electricity on spot and contract markets. This study proposes a new formulation of the unit commitment problem of electric power generators in a restructured electricity market. Under these conditions, an electric power generation company will have the option to buy or sell from a power pool in addition to producing electricity on its own. The unit commitment problem is expressed as a stochastic optimization problem in which the objective is to maximize expected profits and the decisions are required to meet the standard operating constraints. Under the assumption of competitive market and price taking, it is depicted that the unit commitment schedule for a collection of N generation units can be solved by considering each unit separately. The volatility of the spot market price of electricity is represented by a stochastic model. This paper uses probabilistic dynamic programming to solve the stochastic optimization problem pertaining to unit commitment. It is shown that for a market of 150 units the proposed unit commitment can be accurately solved in a reasonable time by using the normal, Edgeworth, or Monte Carlo approximation methods.

  15. Power quality improvement of unbalanced power system with distributed generation units

    DEFF Research Database (Denmark)

    Hu, Y.; Chen, Zhe; Excell, P.

    2011-01-01

    This paper presents a power electronic system for improving the power quality of the unbalanced distributed generation units in three-phase four-wire system. In the system, small renewable power generation units, such as small PV generator, small wind turbines may be configured as single phase...... generation units. The random nature of renewable power sources may result in significant unbalance in the power network and affect the power quality. An electronic converter system is proposed to correct the system unbalance and harmonics so as to deal with the power quality problems. The operation...... and control of the converter are described. Simulation results have demonstrated that the system can effectively correct the unbalance and enhance the system power quality....

  16. Bursting neurons and ultrasound avoidance in crickets.

    Science.gov (United States)

    Marsat, Gary; Pollack, Gerald S

    2012-01-01

    Decision making in invertebrates often relies on simple neural circuits composed of only a few identified neurons. The relative simplicity of these circuits makes it possible to identify the key computation and neural properties underlying decisions. In this review, we summarize recent research on the neural basis of ultrasound avoidance in crickets, a response that allows escape from echolocating bats. The key neural property shaping behavioral output is high-frequency bursting of an identified interneuron, AN2, which carries information about ultrasound stimuli from receptor neurons to the brain. AN2's spike train consists of clusters of spikes - bursts - that may be interspersed with isolated, non-burst spikes. AN2 firing is necessary and sufficient to trigger avoidance steering but only high-rate firing, such as occurs in bursts, evokes this response. AN2 bursts are therefore at the core of the computation involved in deciding whether or not to steer away from ultrasound. Bursts in AN2 are triggered by synaptic input from nearly synchronous bursts in ultrasound receptors. Thus the population response at the very first stage of sensory processing - the auditory receptor - already differentiates the features of the stimulus that will trigger a behavioral response from those that will not. Adaptation, both intrinsic to AN2 and within ultrasound receptors, scales the burst-generating features according to the stimulus statistics, thus filtering out background noise and ensuring that bursts occur selectively in response to salient peaks in ultrasound intensity. Furthermore AN2's sensitivity to ultrasound varies adaptively with predation pressure, through both developmental and evolutionary mechanisms. We discuss how this key relationship between bursting and the triggering of avoidance behavior is also observed in other invertebrate systems such as the avoidance of looming visual stimuli in locusts or heat avoidance in beetles.

  17. Propeller tone bursts

    Science.gov (United States)

    Succi, G. P.; Munro, D. H.; Ingard, K. U.

    1983-01-01

    Intense high frequency (25-38 kHz) tone bursts have been observed in acoustic tests of a scale model of a general aviation propeller. The amplitude of the tone burst is approximately equal to the amplitude of the propeller noise signature. The conditions necessary for the production of these tone bursts are described. The experiments indicate that the origin of these bursts is a periodic flow oscillation on the suction surface of the propeller blade tips which may be due to the interaction between an oscillating shock wave and a laminar boundary layer.

  18. Steam generation unit in a simple version of biomass based small cogeneration unit

    Directory of Open Access Journals (Sweden)

    Sornek Krzysztof

    2014-01-01

    Full Text Available The organic Rankine cycle (ORC is a very promising process for the conversion of low or medium temperature heat to electricity in small and micro scale biomass powered systems. Classic ORC is analogous to Clausius–Rankine cycle in a steam power plant, but instead of water it uses low boiling, organic working fluids. Seeking energy and economical optimization of biomass-based ORC systems, we have proposed some modifications e.g. in low boiling fluid circuit construction. Due to the fact that the operation of a micro steam turbine is rather inefficient from the technical and economic point of view, a specially modified air compressor can be used as a steam piston engine. Such engine should be designed to work at low pressure of the working medium. Studies regarding the first version of the prototype installation were focused on the confirmation of applicability of a straw boiler in the prototype ORC power system. The results of the previous studies and the studies described in the paper (on the new cogeneration unit confirmed the high potential of the developed solution. Of course, many further studies have to be carried out.

  19. Bursts from the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Silk, J. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)]. E-mail: les@mppmu.mpg.de

    2006-07-27

    Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of pheno associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse.

  20. The design and practice of giant hydro-turbine generating units of Three Gorges Project%The design and practice of giant hydro-turbine generating units of Three Gorges Project

    Institute of Scientific and Technical Information of China (English)

    Shao Jianxiong; Liu Jingwang; Yuan Dafu

    2011-01-01

    The main technical problems that should be considered in the design of hydro-turbine generating units of Three Gorges Project (TGP) are analyzed;the key technical researches performed are summarized, and the parameters of hydro-turbine generating units are optimized through the study on key technical problems. The unit operation indicates that the performance of the hydro-turbine generating units is excellent, and the units can operate in a safe, stable and highly efficient mode for a long term. Therefore, it is verified effectively that the general technical design of units is scientific and rational.

  1. Coalition of distributed generation units to virtual power players - a game theory approach

    DEFF Research Database (Denmark)

    Morais, Hugo; Sousa, Tiago M; Santos, Gabriel

    2015-01-01

    of the classifications that were attributed by each VPP to the distributed generation units, as well as in the analysis of the previous established contracts by each player. The proposed classification model is based in fourteen parameters including technical, economical and behavioural ones. Depending of the VPP...... and the existence of new management players such as several types of aggregators. This paper proposes a methodology to facilitate the coalition between distributed generation units originating Virtual Power Players (VPP) considering a game theory approach. The proposed approach consists in the analysis...

  2. Feasibility Analysis of Liquefying Oxygen Generated from Water Electrolysis Units on Lunar Surface

    Science.gov (United States)

    Jeng, Frank F.

    2009-01-01

    Concepts for liquefying oxygen (O2) generated from water electrolysis subsystems on the Lunar surface were explored. Concepts for O2 liquefaction units capable of generating 1.38 lb/hr (0.63 kg/hr) liquid oxygen (LOX) were developed. Heat and mass balance calculations for the liquefaction concepts were conducted. Stream properties, duties of radiators, heat exchangers and compressors for the selected concepts were calculated and compared.

  3. Evolving Distributed Generation Support Mechanisms: Case Studies from United States, Germany, United Kingdom, and Australia (Chinese translation)

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengru [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lowder, Travis R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tian, Tian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-07

    This is the Chinese translation of NREL/TP-6A20-67613. This report expands on a previous National Renewable Energy Laboratory (NREL) technical report (Lowder et al. 2015) that focused on the United States' unique approach to distributed generation photovoltaics (DGPV) support policies and business models. While the focus of that report was largely historical (i.e., detailing the policies and market developments that led to the growth of DGPV in the United States), this report looks forward, narrating recent changes to laws and regulations as well as the ongoing dialogues over how to incorporate distributed generation (DG) resources onto the electric grid. This report also broadens the scope of Lowder et al. (2015) to include additional countries and technologies. DGPV and storage are the principal technologies under consideration (owing to market readiness and deployment volumes), but the report also contemplates any generation resource that is (1) on the customer side of the meter, (2) used to, at least partly, offset a host's energy consumption, and/or (3) potentially available to provide grid support (e.g., through peak shaving and load shifting, ancillary services, and other means).

  4. Bursting neurons and ultrasound avoidance in crickets

    Directory of Open Access Journals (Sweden)

    Gary eMarsat

    2012-07-01

    Full Text Available Decision making in invertebrates often relies on simple neural circuits composed of only a few identified neurons. The relative simplicity of these circuits makes it possible to identify the key computation and neural properties underlying decisions. In this review, we summarize recent research on the neural basis of ultrasound avoidance in crickets, a response that allows escape from echolocating bats. The key neural property shaping behavioral output is high-frequency bursting of an identified interneuron, AN2, which carries information about ultrasound stimuli from receptor neurons to the brain. AN2's spike train consists of clusters of spikes –bursts– that may be interspersed with isolated, non-burst spikes. AN2 firing is necessary and sufficient to trigger avoidance steering but only high-rate firing, such as occurs in bursts, evokes this response. AN2 bursts are therefore at the core of the computation involved in deciding whether or not to steer away from ultrasound. Bursts in AN2 are triggered by synaptic input from nearly synchronous bursts in ultrasound receptors. Thus the population response at the very first stage of sensory processing –the auditory receptor- already differentiates the features of the stimulus that will trigger a behavioral response from those that will not. Adaptation, both intrinsic to AN2 and within ultrasound receptors, scales the burst-generating features according to the stimulus statistics, thus filtering out background noise and ensuring that bursts occur selectively in response to salient peaks in ultrasound intensity. Furthermore AN2’s sensitivity to ultrasound varies adaptively with predation pressure, through both developmental and evolutionary mechanisms. We discuss how this key relationship between bursting and the triggering of avoidance behavior is also observed in other invertebrate systems such as the avoidance of looming visual stimuli in locusts or heat avoidance in beetles.

  5. First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corpuz, A.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalmus, P.; Kalogera, V.; Kamaretsos, I.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Loew, K.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Santamaria, L.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

    2016-11-01

    We present results from a search for gravitational-wave bursts coincident with two core-collapse supernovae observed optically in 2007 and 2011. We employ data from the Laser Interferometer Gravitational-wave Observatory (LIGO), the Virgo gravitational-wave observatory, and the GEO 600 gravitational-wave observatory. The targeted core-collapse supernovae were selected on the basis of (1) proximity (within approximately 15 Mpc), (2) tightness of observational constraints on the time of core collapse that defines the gravitational-wave search window, and (3) coincident operation of at least two interferometers at the time of core collapse. We find no plausible gravitational-wave candidates. We present the probability of detecting signals from both astrophysically well-motivated and more speculative gravitational-wave emission mechanisms as a function of distance from Earth, and discuss the implications for the detection of gravitational waves from core-collapse supernovae by the upgraded Advanced LIGO and Virgo detectors.

  6. A First Targeted Search for Gravitational-Wave Bursts from Core-Collapse Supernovae in Data of First-Generation Laser Interferometer Detectors

    CERN Document Server

    Abbott, B P; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Behnke, B; Bejger, M; Bell, A S; Bell, C J; Berger, B K; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bojtos, P; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Cahillane, C; Bustillo, J Calder'on; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Diaz, J Casanueva; Casentini, C; Caudill, S; Cavagli`a, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Baiardi, L Cerboni; Cerretani, G; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corpuz, A; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J -P; Countryman, S T; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dattilo, V; Dave, I; Daveloza, H P; Davier, M; Davies, G S; Daw, E J; Day, R; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Del'eglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; D'iaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dojcinoski, G; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fournier, J -D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; Gonz'alez, G; Castro, J M Gonzalez; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Holz, D E; Hopkins, P; Hosken, D J; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J -M; Isi, M; Islas, G; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jim'enez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalmus, P; Kalogera, V; Kamaretsos, I; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; K'ef'elian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalaidovski, A; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chunglee; Kim, J; Kim, K; Kim, Nam-Gyu; Kim, Namjun; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Kokeyama, K; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Kr'olak, A; Krueger, C; Kuehn, G; Kumar, P; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Levine, B M; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Loew, K; Logue, J; Lombardi, A L; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; L"uck, H; Lundgren, A P; Luo, J; Lynch, R; Ma, Y; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; na-Sandoval, F Maga; Magee, R M; Mageswaran, M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandel, I; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; M'arka, S; M'arka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martin, R M; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mendoza-Gandara, D; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, K N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nedkova, K; Nelemans, G; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ott, C D; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Pereira, R; Perreca, A; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S S; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; P"urrer, M; Qi, H; Qin, J; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Ricci, F; Riles, K; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosi'nska, D; Rowan, S; R"udiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Santamaria, L; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Sch"onbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sentenac, D; Sequino, V; Sergeev, A; Serna, G; Setyawati, Y; Sevigny, A; Shaddock, D A; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Simakov, D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sutton, P J; Swinkels, B L; Szczepa'nczyk, M J; Tacca, M; Talukder, D; Tanner, D B; T'apai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; T"oyr"a, D; Travasso, F; Traylor, G; Trifir`o, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; van Bakel, N; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Vass, S; Vas'uth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Vicer'e, A; Vinciguerra, S; Vine, D J; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Worden, J; Wright, J L; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yap, M J; Yu, H; Yvert, M; zny, A Zadro; Zangrando, L; Zanolin, M; Zendri, J -P; Zevin, M; Zhang, F; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J

    2016-01-01

    We present results from a search for gravitational-wave bursts coincident with a set of two core-collapse supernovae observed between 2007 and 2011. We employ data from the Laser Interferometer Gravitational-wave Observatory (LIGO), the Virgo gravitational-wave observatory, and the GEO 600 gravitational-wave observatory. The targeted core-collapse supernovae were selected on the basis of (1) proximity (within approximately 15 Mpc), (2) tightness of observational constraints on the time of core collapse that defines the gravitational-wave search window, and (3) coincident operation of at least two interferometers at the time of core collapse. We find no plausible gravitational-wave candidates. We present the probability of detecting signals from both astrophysically well-motivated and more speculative gravitational-wave emission mechanisms as a function of distance from Earth, and discuss the implications for the detection of gravitational waves from core-collapse supernovae by the upgraded Advanced LIGO and V...

  7. Bubble bursting as an aerosol generation mechanism during an oil spill in the deep-sea environment: laboratory experimental demonstration of the transport pathway.

    Science.gov (United States)

    Ehrenhauser, Franz S; Avij, Paria; Shu, Xin; Dugas, Victoria; Woodson, Isaiah; Liyana-Arachchi, Thilanga; Zhang, Zenghui; Hung, Francisco R; Valsaraj, Kalliat T

    2014-01-01

    Oil spills in the deep-sea environment such as the 2010 Deep Water Horizon oil spill in the Gulf of Mexico release vast quantities of crude oil into the sea-surface environment. Various investigators have discussed the marine transport and fate of the oil into different environmental compartments (air, water, sediment, and biota). The transport of the oil into the atmosphere in these previous investigations has been limited to only evaporation, a volatility dependent pathway. In this work, we studied the aerosolization of oil spill matter via bursting bubbles as they occur during whitecaps in a laboratory aerosolization reactor. By evaluating the alkane content in oil mousse, crude oil, the gas phase, and particulate matter we clearly demonstrate that aerosolization via bursting bubbles is a solubility and volatility independent transport pathway for alkanes. The signature of alkane fractions in the native oil and aerosolized matter matched well especially for the less volatile alkanes (C20-C29). Scanning electron microscope interfaced with energy dispersive X-ray images identified the carbon fractions associated with salt particles of aerosols. Theoretical molecular dynamics simulations in the accompanying paper lend support to the observed propensity for alkanes at air-salt water interfaces of breaking bubbles and the produced droplets. The presence of a dispersant in the aqueous phase increased the oil ejection rate at the surface especially for the C20-C29 alkanes. The information presented here emphasizes the need to further study sea-spray aerosols as a possible transport vector for spilled oil in the sea surface environment.

  8. Dynamic encoding of natural luminance sequences by LGN bursts.

    Directory of Open Access Journals (Sweden)

    Nicholas A Lesica

    2006-07-01

    Full Text Available In the lateral geniculate nucleus (LGN of the thalamus, visual stimulation produces two distinct types of responses known as tonic and burst. Due to the dynamics of the T-type Ca(2+ channels involved in burst generation, the type of response evoked by a particular stimulus depends on the resting membrane potential, which is controlled by a network of modulatory connections from other brain areas. In this study, we use simulated responses to natural scene movies to describe how modulatory and stimulus-driven changes in LGN membrane potential interact to determine the luminance sequences that trigger burst responses. We find that at low resting potentials, when the T channels are de-inactivated and bursts are relatively frequent, an excitatory stimulus transient alone is sufficient to evoke a burst. However, to evoke a burst at high resting potentials, when the T channels are inactivated and bursts are relatively rare, prolonged inhibitory stimulation followed by an excitatory transient is required. We also observe evidence of these effects in vivo, where analysis of experimental recordings demonstrates that the luminance sequences that trigger bursts can vary dramatically with the overall burst percentage of the response. To characterize the functional consequences of the effects of resting potential on burst generation, we simulate LGN responses to different luminance sequences at a range of resting potentials with and without a mechanism for generating bursts. Using analysis based on signal detection theory, we show that bursts enhance detection of specific luminance sequences, ranging from the onset of excitatory sequences at low resting potentials to the offset of inhibitory sequences at high resting potentials. These results suggest a dynamic role for burst responses during visual processing that may change according to behavioral state.

  9. Grandparents in the United States and the Republic of China: A Comparison of Generations and Cultures.

    Science.gov (United States)

    Strom, Robert D.; Strom, Shirley K.; Wang, Chih-Mei; Shen, Yuh-Ling; Griswold, Dianne; Chan, Hou-Sheng; Yang, Chu-Yin

    1999-01-01

    Examines grandparent behaviors in the United States and in the Republic of China to identify curriculum themes for helping them learn to adjust to their changing roles. Results revealed significant differences in perceptions about grandparents across cultures as well as between generations within cultures. Provides specific guidelines and…

  10. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  11. Enhanced Control for a Direct-driven Permanent Synchronous Generator Wind-power Generation System with Flywheel Energy Storage Unit Under Unbalanced Grid Fault

    DEFF Research Database (Denmark)

    Yao, Jun; Zhou, Te; Hu, Weihao;

    2015-01-01

    This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under......, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally......, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy...

  12. Graphic processing unit accelerated real-time partially coherent beam generator

    Science.gov (United States)

    Ni, Xiaolong; Liu, Zhi; Chen, Chunyi; Jiang, Huilin; Fang, Hanhan; Song, Lujun; Zhang, Su

    2016-07-01

    A method of using liquid-crystals (LCs) to generate a partially coherent beam in real-time is described. An expression for generating a partially coherent beam is given and calculated using a graphic processing unit (GPU), i.e., the GeForce GTX 680. A liquid-crystal on silicon (LCOS) with 256 × 256 pixels is used as the partially coherent beam generator (PCBG). An optimizing method with partition convolution is used to improve the generating speed of our LC PCBG. The total time needed to generate a random phase map with a coherence width range from 0.015 mm to 1.5 mm is less than 2.4 ms for calculation and readout with the GPU; adding the time needed for the CPU to read and send to LCOS with the response time of the LC PCBG, the real-time partially coherent beam (PCB) generation frequency of our LC PCBG is up to 312 Hz. To our knowledge, it is the first real-time partially coherent beam generator. A series of experiments based on double pinhole interference are performed. The result shows that to generate a laser beam with a coherence width of 0.9 mm and 1.5 mm, with a mean error of approximately 1%, the RMS values needed 0.021306 and 0.020883 and the PV values required 0.073576 and 0.072998, respectively.

  13. Dynamic Economic Dispatch Using Hybrid DE-SQP for Generating Units with Valve-Point Effects

    Directory of Open Access Journals (Sweden)

    A. M. Elaiw

    2012-01-01

    Full Text Available This paper presents hybrid differential evolution (DE and sequential quadratic programming (SQP for solving the dynamic economic dispatch (DED problem for generating units with valve-point effects. DE is used as a global optimizer and SQP is used as a fine tuning to determine the optimal solution at the final. The feasibility of the proposed method is validated with five-and ten-unit test systems. Results obtained by DE-SQP method are compared with other techniques in the literature.

  14. Fast high-resolution computer-generated hologram computation using multiple graphics processing unit cluster system.

    Science.gov (United States)

    Takada, Naoki; Shimobaba, Tomoyoshi; Nakayama, Hirotaka; Shiraki, Atsushi; Okada, Naohisa; Oikawa, Minoru; Masuda, Nobuyuki; Ito, Tomoyoshi

    2012-10-20

    To overcome the computational complexity of a computer-generated hologram (CGH), we implement an optimized CGH computation in our multi-graphics processing unit cluster system. Our system can calculate a CGH of 6,400×3,072 pixels from a three-dimensional (3D) object composed of 2,048 points in 55 ms. Furthermore, in the case of a 3D object composed of 4096 points, our system is 553 times faster than a conventional central processing unit (using eight threads).

  15. Fast Radio Bursts

    Indian Academy of Sciences (India)

    Akshaya Rane; Duncan Lorimer

    2017-09-01

    We summarize our current state of knowledge of fast radio bursts (FRBs) which were first discovered a decade ago. Following an introduction to radio transients in general, including pulsars and rotating radio transients, we discuss the discovery of FRBs. We then discuss FRB follow-up observations in the context of repeat bursts before moving on to review propagation effects on FRB signals, FRB progenitor models and an outlook on FRBs as potential cosmological tools.

  16. Intense generation of respirable metal nanoparticles from a low-power soldering unit

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, Virginia [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Irusta, Silvia [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain); Balas, Francisco [Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain); Instituto de Carboquímica – Consejo Superior de Investigaciones Científicas (ICB-CSIC), 50018 Zaragoza (Spain); Santamaria, Jesus, E-mail: Jesus.Santamaria@unizar.es [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain)

    2013-07-15

    Highlights: • Intense generation of nanoparticles in the breathing range from a flux-soldering unit is detected. • Coagulation in the aerosol phase leads to 200-nm respirable nanoparticles up to 30 min after operation. • Nanoparticle concentration in the working environment depends on the presence of ambient air. • Metal-containing nanoparticles are collected in TEM grids and filters in the hundreds of nanometer range. -- Abstract: Evidence of intense nanoparticle generation from a low power (45 W) flux soldering unit is presented. This is a familiar device often used in daily life, including home repairs and school electronic laboratories. We demonstrate that metal-containing nanoparticles may reach high concentrations (ca. 10{sup 6} particles/cm{sup 3}) within the breathing range of the operator, with initial size distributions centered at 35–60 nm The morphological and chemical analysis of nanoparticle agglomerates collected on TEM grids and filters confirms their multiparticle structure and the presence of metals.

  17. Automatic generation control with thyristor controlled series compensator including superconducting magnetic energy storage units

    Directory of Open Access Journals (Sweden)

    Saroj Padhan

    2014-09-01

    Full Text Available In the present work, an attempt has been made to understand the dynamic performance of Automatic Generation Control (AGC of multi-area multi-units thermal–thermal power system with the consideration of Reheat turbine, Generation Rate Constraint (GRC and Time delay. Initially, the gains of the fuzzy PID controller are optimized using Differential Evolution (DE algorithm. The superiority of DE is demonstrated by comparing the results with Genetic Algorithm (GA. After that performance of Thyristor Controlled Series Compensator (TCSC has been investigated. Further, a TCSC is placed in the tie-line and Superconducting Magnetic Energy Storage (SMES units are considered in both areas. Finally, sensitivity analysis is performed by varying the system parameters and operating load conditions from their nominal values. It is observed that the optimum gains of the proposed controller need not be reset even if the system is subjected to wide variation in loading condition and system parameters.

  18. The use of propeller turbines in low head stand alone micro hydro electric power generation units

    Energy Technology Data Exchange (ETDEWEB)

    Demetriades, G.M.; Williams, A.A.; Smith, N.P.A. [Nottingham Trent Univ. (United Kingdom). Dept. of Electrical Engineering

    1995-07-01

    The mountainous regions of developing countries offer a great potential for small scale hydroelectric schemes, running as stand alone units. Such schemes with power output less than 100 kW are usually referred to as micro-hydro power generation units. For low - head sites (available head less than 10 m), there is a vast number of suitable sites in countries with less mountainous areas and high rainfall, or extensive irrigation canals. The present paper introduces the design features of an appropriate propeller turbine design. The turbine will be directly coupled to an induction generator. The design requirements, materials selection and manufacturing processes are analysed with respect to experiences from pilot projects within the UK and abroad. (author)

  19. Advanced Stirling Radioisotope Generator Engineering Unit 2 (ASRG EU2) Final Assembly

    Science.gov (United States)

    Oriti, Salvatore M.

    2015-01-01

    NASA Glenn Research Center (GRC) has recently completed the assembly of a unique Stirling generator test article for laboratory experimentation. Under the Advanced Stirling Radioisotope Generator (ASRG) flight development contract, NASA GRC initiated a task to design and fabricate a flight-like generator for in-house testing. This test article was given the name ASRG Engineering Unit 2 (EU2) as it was effectively the second engineering unit to be built within the ASRG project. The intent of the test article was to duplicate Lockheed Martin's qualification unit ASRG design as much as possible to enable system-level tests not previously possible at GRC. After the cancellation of the ASRG flight development project, the decision was made to continue the EU2 build, and make use of a portion of the hardware from the flight development project. GRC and Lockheed Martin engineers collaborated to develop assembly procedures, leveraging the valuable knowledge gathered by Lockheed Martin during the ASRG development contract. The ASRG EU2 was then assembled per these procedures at GRC with Lockheed Martin engineers on site. The assembly was completed in August 2014. This paper details the components that were used for the assembly, and the assembly process itself.

  20. 78 FR 14842 - Crystal River Nuclear Generating Plant, Unit 3; Application for Renewal of License to Facility...

    Science.gov (United States)

    2013-03-07

    ... COMMISSION Crystal River Nuclear Generating Plant, Unit 3; Application for Renewal of License to Facility... operate the Crystal River Nuclear Generating Plant, Unit 3 (CR3), at 2609 megawatts thermal. The FPC... located near Crystal River, FL; the current operating license for the CR3 expires on December 3, 2016. The...

  1. The Relevance of Generation Interconnection Procedures to Feed-in Tariffs in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Sari [Exeter Associates, Inc., Columbia, MD (United States); Porter, Kevin [Exeter Associates, Inc., Columbia, MD (United States); Rogers, Jennifer [Exeter Associates, Inc., Columbia, MD (United States)

    2010-10-01

    Feed-in tariffs (FITs) have been used to promote renewable electricity development in over 40 countries throughout the past two decades. These policies generally provide guaranteed prices for the full system output from eligible generators for a fixed time period (typically 15–20 years). Due in part to the success of FIT policies in Europe, some jurisdictions in the United States are considering implementing similar policies, and a few have already put such policies in place. This report is intended to offer some guidance to policymakers and regulators on how generator interconnection procedures may affect the implementation of FITs and how state generator interconnection procedures can be formulated to support state renewable energy objectives. This report is based on a literature review of model interconnection procedures formulated by several organizations, as well as other documents that have reviewed, commented on, and in some cases, ranked state interconnection procedures.

  2. Relevance of Generation Interconnection Procedures to Feed-in Tariffs in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Fink, S.; Porter, K.; Rogers, J.

    2010-10-01

    Feed-in tariffs (FITs) have been used to promote renewable electricity development in over 40 countries throughout the past two decades. These policies generally provide guaranteed prices for the full system output from eligible generators for a fixed time period (typically 15-20 years). Due in part to the success of FIT policies in Europe, some jurisdictions in the United States are considering implementing similar policies, and a few have already put such policies in place. This report is intended to offer some guidance to policymakers and regulators on how generator interconnection procedures may affect the implementation of FITs and how state generator interconnection procedures can be formulated to support state renewable energy objectives. This report is based on a literature review of model interconnection procedures formulated by several organizations, as well as other documents that have reviewed, commented on, and in some cases, ranked state interconnection procedures.

  3. A simplified propeller turbine runner design for stand alone micro-hydro power generation units

    Energy Technology Data Exchange (ETDEWEB)

    Demetriades, G.M.; Williams, A.A.; Smith, N.P.A. [Nottingham Trent University (United Kingdom). Micro-Hydro Research Group

    1996-07-01

    In most developing countries, the vast majority of potential micro-hydro power generation sites, i.e. with power outputs up to 100 kW, are found in areas with high rainfall or extensive irrigation works with small canal drops. These sites, where the available head does not exceed 5 m, are usually referred to as low head sites. The present paper introduces a simplified design of a propeller turbine suitable for direct coupling to an induction generator. The use of such a unit is a promising technology for setting up low-head power generation schemes for village electrification in developing countries. Emphasis is given to the hydraulic design of the runner blades which are made of constant thickness sheets of metal. The use of such a shape is ideal for low cost manufacturing in developing countries as it enables local skills and materials to be used. (author)

  4. Interplanetary Type IV Bursts

    CERN Document Server

    Hillaris, Alexander; Nindos, Alexander

    2016-01-01

    In this work we study the characteristics of moving type IV radio bursts which extend to the hectometric wavelengths (interplanetary type IV or type IV IP bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprised 48 Interplanetary type IV bursts observed by the Wind/WAVES in the 13.825 MHz?20 KHz frequency range. The dynamic spec tra of the RSTN, DAM, ARTEMIS-IV, CULGOORA, Hiraiso and IZMIRAN Radio-spectrographs were used to track the evolution of the events in the low corona; these were supplemented with SXR ?ux recordings from GOES and CME data from LASCO. Positional information for the coronal bursts were obtained by the Nan\\c{c}ay radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs and SXR ?ares. The majority of the events (45) were characterized as compact; their duration was on average 106 min. This type of events were, mostly, associated with M and X class ?ares (40 out of 45) and fast CMEs; 32 of these events had CME...

  5. The Identification of Two Different Spectral Types of Pulses in Gamma-Ray Bursts

    Science.gov (United States)

    Pendleton, G. N. (Editor); Paciesas, W. S. (Editor); Briggs, M. S. (Editor); Preece, R. D. (Editor); Mallozzi, R. S. (Editor); Meegan, C. A. (Editor); Horack, J. M. (Editor); Fishman, G. J. (Editor); Band, D. L. (Editor); Matteson, J. L. (Editor); Skelton, R. T. (Editor); Hakkila, J. (Editor); Ford, L. A. (Editor); Kouveliotou, C. (Editor); Koshut, T. M. (Editor)

    1997-01-01

    It is shown in this study that two different types of spectral emission are generally produced in gamma-ray bursts. A subset of bursts is identified that exhibits a marked lack of fluence above 300 keV, and these bursts are shown to have luminosities about an order of magnitude lower than bursts with significant fluence above 300 keV. The bursts lacking emission above 300 keV exhibit an effectively homogeneous intensity distribution. In addition, it is shown that both types of emission are common in many bursts, demonstrating that a single source object is capable of generating both of them. These results strongly favor a gamma-ray burst source object that produces two different types of emission with varying degrees of superposition. The impact of this behavior is strong enough that it affects the properties of the burst intensity distribution, as well as the burst spectral characteristics.

  6. Development of hydraulic power unit and accumulator charging circuit for electricity generation, storage and distribution

    Institute of Scientific and Technical Information of China (English)

    C.N.Okoye; JIANG Ji-hai; LIU Hai-chang

    2008-01-01

    It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to induction motor to drive cylinder loads. During upstroke operation, the variable pump/motor (P/M) driven by both electric motor and the second (P/M) works as hydraulic pump and output flow to the cylinders which drive the load. During load deceleration, the cylinders work as pump while the operation of the two secondary units are reversed, the variable (P/M) works as a motor generating a torque with the electric motor to drive the other(P/M) which transforms mechanical energy to hydraulic energy that is saved in the accumulator. When the en-ergy storage capacity of the accumulator is attained as the operation continues, energy storage to the accumulator is thermostatically stopped while the induction motor begins to work as a generator and generates electricity that is stored in the power distribution unit. Simulations were performed using a limited PT2 Block, I.e. 2nd-ordertransfer function with limitation of slope and signal output to determine suitable velocity of the cylinder which will match high performance and system stability. A mathematical model suited to the simulation of the hydrau-lic accumulator both in an open-or close-loop system is presented. The quest for improvement of lower energy capacity storage, saving and re-utilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes necessitates this research. The outcome of the research appears to be very efficient for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.

  7. A Burst to See

    Science.gov (United States)

    2008-04-01

    On 19 March, Nature was particularly generous and provided astronomers with the wealth of four gamma-ray bursts on the same day. But that was not all: one of them is the most luminous object ever observed in the Universe. Despite being located in a distant galaxy, billions of light years away, it was so bright that it could have been seen, for a brief while, with the unaided eye. ESO PR Photo 08a/08 ESO PR Photo 08a/08 The REM Telescope and TORTORA Camera Gamma-ray bursts (GRBs) are short flashes of energetic gamma-rays lasting from less than a second to several minutes. They release a tremendous quantity of energy in this short time making them the most powerful events since the Big Bang. It is now widely accepted that the majority of the gamma-ray bursts signal the explosion of very massive, highly evolved stars that collapse into black holes. Gamma-ray bursts, which are invisible to our eyes, are discovered by telescopes in space. After releasing their intense burst of high-energy radiation, they become detectable for a short while in the optical and in the near-infrared. This 'afterglow' fades very rapidly, making detailed analysis possible for only a few hours after the gamma-ray detection. This analysis is important in particular in order to determine the GRB's distance and, hence, intrinsic brightness. The gamma-ray burst GRB 080319B was detected by the NASA/STFC/ASI Swift satellite. "It was so bright that it almost blinded the Swift instruments for a while," says Guido Chincarini, Italian principal investigator of the mission. A bright optical counterpart was soon identified in the Boötes Constellation (the "Bear Driver" or "Herdsman"). A host of ground-based telescopes reacted promptly to study this new object in the sky. In particular, the optical emission was detected by a few wide-field cameras on telescopes that constantly monitor a large fraction of the sky, including the TORTORA camera in symbiosis with the 0.6-m REM telescope located at La Silla

  8. Emissions Implications of Downscaled Electricity Generation Scenarios for the Western United States

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Gregory L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); O' Connell, Matthew [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nsanzineza, Rene [University of Colorado; Milford, Jana [University of Colorado

    2017-07-27

    This study explores how emissions from electricity generation in the Western Interconnection region of the U.S. might respond in circa 2030 to contrasting scenarios for fuel prices and greenhouse gas (GHG) emissions fees. We examine spatial and temporal variations in generation mix across the region and year using the PLEXOS unit commitment and dispatch model with a production cost model database adapted from the Western Electricity Coordinating Council. Emissions estimates are computed by combining the dispatch model results with unit-specific, emissions-load relationships. Wind energy displaces natural gas and coal in scenarios with relatively expensive natural gas or with GHG fees. Correspondingly, annual emissions of NOx, SO2, and CO2 are reduced by 20-40% in these cases. NOx emissions, which are a concern as a precursor of ground-level ozone, are relatively high and consistent across scenarios during summer, when peak electricity loads occur and wind resources in the region are comparatively weak. Accounting for the difference in start-up versus stabilized NOx emissions rates for natural gas plants had little impact on region-wide emissions estimates due to the dominant contribution from coal-fired plants, but would be more important in the vicinity of the natural gas units.

  9. Levelised unit electricity cost comparison of alternate technologies for baseload generation in Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Ayres, M.; McRae, M.; Stogran, M.

    2004-08-15

    This report provides a comparison of the lifetime cost of constructing, operating and decommissioning new generation suitable for supplying baseload power by early in the next decade. New baseload generation options in Ontario are nuclear, coal-fired steam turbines or combined cycle gas turbines (CCGT). Nuclear and coal-fired units are characterised by high capital costs and low operating costs. As such, they are candidates for baseload operation only. Gas-fired generation is characterised by lower capital costs and higher operating costs and thus may meet the requirements for operation as peaking and/or baseload generation. The comparison of baseload generating technologies is made by reference to the estimated levelised unit electricity cost (LUEC). The LUEC can be thought of as a 'supply cost', where the unit cost is the price needed to recover all costs over the period. It is determined by finding the price that sets the sum of all future discounted cash flows (net present value, or NPV) to zero. It can also be thought of as representing the constant real wholesale price of electricity that meets the financing cost, debt repayment, income tax and cash flow constraints associated with the construction operation and decommissioning of a generating plant. Levelised unit cost comparisons are usually made with different sets of financing assumptions. This report considers two base cases, which we describe as 'merchant' and 'public' financing. The term 'merchant plant' is used to refer to ones that are built and operated by private investors. These investors pay for their capital through debt and by raising equity, and thus pay return on equity and interest on debt throughout their lifetime. These projects include income taxes, both provincial and federal. Publicly financed projects typically are not subject to income taxes or to the same constraints on raising finance through issuing debt and equity. However, they are

  10. The Glast Burst Monitor

    Science.gov (United States)

    Meegan, Charles

    2000-01-01

    The Gamma-Ray Large Area Space Telescope (GLAST) will include a secondary instrument to augment the observatory's capabilities for GRB studies. The GLAST Burst Monitor (GBK is a collaboration between Marshall Space Flight Center, the University of Huntsville, Alabama, and the Max Plank Institute for Extraterrestrial Physics. The purpose of the GBM is to extend energy coverage below the main instrument's lower limit of about 20 MeV, and to provide an on-board burst trigger and approximate location. The instrument consists of twelve NaI detectors and two BGO detectors. This combination provides energy coverage from a few keV up to about 30 MeV.

  11. Interplanetary Type IV Bursts

    Science.gov (United States)

    Hillaris, A.; Bouratzis, C.; Nindos, A.

    2016-08-01

    We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal

  12. Analysis on Electrical Fast Transient/Burst Immunity of Merging Unit%合并单元的电快速瞬变脉冲群抗扰度分析

    Institute of Scientific and Technical Information of China (English)

    徐丽青; 丁泉; 史志伟; 余华武

    2014-01-01

    According to the problem of merging unit during the test on electrical fast transient/burst (EFT/B), the characteristics of the EFT/B are analyzed and the anti-interference methods for solving the EFT/B problem of the merging unit are proposed.The improved filter structure with metalized polyester film capacitors and transient voltage suppressor(TVS)is proposed to enhance high-frequency interference suppression.The wiring and layout of the mother PCB is optimized to reduce the impact of coupling between different circuits.The results of the test show that the improved merging unit is able to meet the requirements of EFT/B of grade 4.%针对合并单元在电快速瞬变脉冲群试验中出现的问题,分析了电快速瞬变脉冲群干扰的特点,提出一种适用于合并单元的电快速瞬变脉冲群的抗扰度措施。提出采用金属化聚酯薄膜电容和瞬态抑制二极管改进交流回路的滤波结构,增强对高频干扰的抑制能力。通过优化母板PCB布局和布线,减少各回路之间耦合的影响。试验结果表明,采用改进后的合并单元能通过电快速瞬变脉冲群4级的要求。

  13. Developing a tool to estimate water withdrawal and consumption in electricity generation in the United States.

    Energy Technology Data Exchange (ETDEWEB)

    Wu, M.; Peng, J. (Energy Systems); ( NE)

    2011-02-24

    Freshwater consumption for electricity generation is projected to increase dramatically in the next couple of decades in the United States. The increased demand is likely to further strain freshwater resources in regions where water has already become scarce. Meanwhile, the automotive industry has stepped up its research, development, and deployment efforts on electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs). Large-scale, escalated production of EVs and PHEVs nationwide would require increased electricity production, and so meeting the water demand becomes an even greater challenge. The goal of this study is to provide a baseline assessment of freshwater use in electricity generation in the United States and at the state level. Freshwater withdrawal and consumption requirements for power generated from fossil, nonfossil, and renewable sources via various technologies and by use of different cooling systems are examined. A data inventory has been developed that compiles data from government statistics, reports, and literature issued by major research institutes. A spreadsheet-based model has been developed to conduct the estimates by means of a transparent and interactive process. The model further allows us to project future water withdrawal and consumption in electricity production under the forecasted increases in demand. This tool is intended to provide decision makers with the means to make a quick comparison among various fuel, technology, and cooling system options. The model output can be used to address water resource sustainability when considering new projects or expansion of existing plants.

  14. Bio-inspired benchmark generator for extracellular multi-unit recordings

    Science.gov (United States)

    Mondragón-González, Sirenia Lizbeth; Burguière, Eric

    2017-01-01

    The analysis of multi-unit extracellular recordings of brain activity has led to the development of numerous tools, ranging from signal processing algorithms to electronic devices and applications. Currently, the evaluation and optimisation of these tools are hampered by the lack of ground-truth databases of neural signals. These databases must be parameterisable, easy to generate and bio-inspired, i.e. containing features encountered in real electrophysiological recording sessions. Towards that end, this article introduces an original computational approach to create fully annotated and parameterised benchmark datasets, generated from the summation of three components: neural signals from compartmental models and recorded extracellular spikes, non-stationary slow oscillations, and a variety of different types of artefacts. We present three application examples. (1) We reproduced in-vivo extracellular hippocampal multi-unit recordings from either tetrode or polytrode designs. (2) We simulated recordings in two different experimental conditions: anaesthetised and awake subjects. (3) Last, we also conducted a series of simulations to study the impact of different level of artefacts on extracellular recordings and their influence in the frequency domain. Beyond the results presented here, such a benchmark dataset generator has many applications such as calibration, evaluation and development of both hardware and software architectures. PMID:28233819

  15. Arc burst pattern analysis fault detection system

    Science.gov (United States)

    Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

    1997-01-01

    A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

  16. A next generation Ultra-Fast Flash Observatory (UFFO-100) for IR/optical observations of the rise phase of gamma-ray bursts

    DEFF Research Database (Denmark)

    Grossan, B.; Park, I.H.; Ahmad, S.

    2012-01-01

    generation of rapid-response space observatory instruments. We list science topics motivating ourinstruments, those that require rapid optical-IR GRB response, including: A survey of GRB rise shapes/times,measurements of optical bulk Lorentz factors, investigation of magnetic dominated (vs. non-magnetic) jet...... models,internal vs. external shock origin of prompt optical emission, the use of GRBs for cosmology, and dust evaporation inthe GRB environment. We also address the impacts of the characteristics of GRB observing on our instrument andobservatory design. We describe our instrument designs and choices...... for a next generation space observatory as a secondinstrument on a low-earth orbit spacecraft, with a 120 kg instrument mass budget. Restricted to relatively modest mass,power, and launch resources, we find that a coded mask X-ray camera with 1024 cm2 of detector area could rapidlylocate about 64...

  17. Graphics processing unit-based quantitative second-harmonic generation imaging.

    Science.gov (United States)

    Kabir, Mohammad Mahfuzul; Jonayat, A S M; Patel, Sanjay; Toussaint, Kimani C

    2014-09-01

    We adapt a graphics processing unit (GPU) to dynamic quantitative second-harmonic generation imaging. We demonstrate the temporal advantage of the GPU-based approach by computing the number of frames analyzed per second from SHG image videos showing varying fiber orientations. In comparison to our previously reported CPU-based approach, our GPU-based image analysis results in ∼10× improvement in computational time. This work can be adapted to other quantitative, nonlinear imaging techniques and provides a significant step toward obtaining quantitative information from fast in vivo biological processes.

  18. A Repeating Fast Radio Burst

    CERN Document Server

    Spitler, L G; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-01-01

    Fast Radio Bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measures (i.e. integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of the fast radio bursts has led several authors to hypothesise that they originate in cataclysmic astrophysical events. Here we report the detection of ten additional bursts from the direction of FRB121102, using the 305-m Arecibo telescope. These new bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and wh...

  19. Soft technologies as generating satisfaction in users of a Family Health Unit

    Directory of Open Access Journals (Sweden)

    Sonia Mara Neves Ferri

    2007-01-01

    Full Text Available This study had the purpose to evaluate the quality of the health service provided at a Family Health Unit (FHU, with emphasis on user satisfaction, based on soft technologies. Furthermore, this study also aimed to analyze the aspects of health care that generated user satisfaction or dissatisfaction regarding attachment, accountability, providing solutions, expectations, relationship, comfort, and access, and to identify recommendations for local interventions. The authors made a general characterization of the population seen at the studied service, and then selected the subjects. The study used a qualitative approach. Data were collected in semi-structured interviews, and ordered using the Collective Subject Discourse (CSD method. The analysis reveals the importance that service users assign to the soft technologies, but also shows the need to reduce the waiting time for medical consultations and referrals, and to obtain access to medication and dental care at the same location. These factors generated great dissatisfaction among users.

  20. Major design issues of molten carbonate fuel cell power generation unit

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.P.

    1996-04-01

    In addition to the stack, a fuel cell power generation unit requires fuel desulfurization and reforming, fuel and oxidant preheating, process heat removal, waste heat recovery, steam generation, oxidant supply, power conditioning, water supply and treatment, purge gas supply, instrument air supply, and system control. These support facilities add considerable cost and system complexity. Bechtel, as a system integrator of M-C Power`s molten carbonate fuel cell development team, has spent substantial effort to simplify and minimize these supporting facilities to meet cost and reliability goals for commercialization. Similiar to other fuels cells, MCFC faces design challenge of how to comply with codes and standards, achieve high efficiency and part load performance, and meanwhile minimize utility requirements, weight, plot area, and cost. However, MCFC has several unique design issues due to its high operating temperature, use of molten electrolyte, and the requirement of CO2 recycle.

  1. Optimal placement and sizing of multiple distributed generating units in distribution

    Directory of Open Access Journals (Sweden)

    D. Rama Prabha

    2016-06-01

    Full Text Available Distributed generation (DG is becoming more important due to the increase in the demands for electrical energy. DG plays a vital role in reducing real power losses, operating cost and enhancing the voltage stability which is the objective function in this problem. This paper proposes a multi-objective technique for optimally determining the location and sizing of multiple distributed generation (DG units in the distribution network with different load models. The loss sensitivity factor (LSF determines the optimal placement of DGs. Invasive weed optimization (IWO is a population based meta-heuristic algorithm based on the behavior of weeds. This algorithm is used to find optimal sizing of the DGs. The proposed method has been tested for different load models on IEEE-33 bus and 69 bus radial distribution systems. This method has been compared with other nature inspired optimization methods. The simulated results illustrate the good applicability and performance of the proposed method.

  2. 降压吹扫技术在某核电站二回路冲管中的应用%Application of Burst-blowing Technique in Pipe Flushing of Steam System Secondary Loop of Nuclear Power Units

    Institute of Scientific and Technical Information of China (English)

    俞长宏

    2016-01-01

    The paper describes the application procedures of burst-blowing technique in pipe flushing of secondary loopsteam system of nuclear power units. The steam pipe purging was analyzed in consideration of purging parameter selection, purging method determination, and preparation and precautions before purging. An idea was presented that the purging parameters could be selected through theoretical calculation, therefore to reduce steam consumption enhance purging efficiency. Check, for the future of such steam pipe blowing significance.%本文简述了降压吹扫技术在某核电机组二回路蒸汽系统冲管中的应用。从吹扫参数的计算、吹扫方法的选择、吹扫准备和吹扫时的有关注意事项等方面对蒸汽管道的吹扫进行了分析,提出通过理论计算作为确定吹扫参数的依据,以降低吹扫的蒸汽消耗量、提高吹扫效率,该蒸汽系统管道吹扫试验的成功对后续同类型核电站的蒸汽管道的吹扫具有借鉴意义。

  3. Taming desynchronized bursting with delays in the Macaque cortical network

    Institute of Scientific and Technical Information of China (English)

    Wang Qing-Yun; Murks Aleksandra; Perc Matja(z); Lu Qi-Shao

    2011-01-01

    Inhibitory coupled bursting Hindmarsh-Rose neurons are considered as constitutive units of the Macaque cortical network. In the absence of information transmission delay the bursting activity is desynchronized, giving rise to spatiotemporally disordered dynamics. This paper shows that the introduction of finite delays can lead to the synchroization of bursting and thus to the emergence of coherent propagating fronts of excitation in the space-time domain.Moreover, it shows that the type of synchronous bursting is uniquely determined by the delay length, with the transitions from one type to the other occurring in a step-like manner depending on the delay. Interestingly, as the delay is tuned close to the transition points, the synchronization deteriorates, which implies the coexistence of different bursting attractors. These phenomena can be observed be different but fixed coupling strengths, thus indicating a new role for information transmission delays in realistic neuronal networks.

  4. Regulation of secretory granule size by the precise generation and fusion of unit granules.

    Science.gov (United States)

    Hammel, Ilan; Lagunoff, David; Galli, Stephen J

    2010-07-01

    Morphometric evidence derived from studies of mast cells, pancreatic acinar cells and other cell types supports a model in which the post-Golgi processes that generate mature secretory granules can be resolved into three steps: (1) fusion of small, Golgi-derived progranules to produce immature secretory granules which have a highly constrained volume; (2) transformation of such immature granules into mature secretory granules, a process often associated with a reduction in the maturing granule's volume, as well as changes in the appearance of its content and (3) fusion of secretory granules of the smallest size, termed 'unit granules', forming granules whose volumes are multiples of the unit granule's volume. Mutations which perturb this process can cause significant pathology. For example, Chediak-Higashi syndrome / lysosomal trafficking regulator (CHS)/(Lyst) mutations result in giant secretory granules in a number of cell types in human beings with the Chediak-Higashi syndrome and in 'beige' (Lyst(bg)/Lyst(bg)) mice. Analysis of the secretory granules of mast cells and pancreatic acinar cells in Lyst-deficient beige mice suggests that beige mouse secretory granules retain the ability to fuse randomly with other secretory granules no matter what the size of the fusion partners. By contrast, in normal mice, the pattern of granule-granule fusion occurs exclusively by the addition of unit granules, either to each other or to larger granules. The normal pattern of fusion is termed unit addition and the fusion evident in cells with CHS/Lyst mutations is called random addition. The proposed model of secretory granule formation has several implications. For example, in neurosecretory cells, the secretion of small amounts of cargo in granules constrained to a very narrow size increases the precision of the information conveyed by secretion. By contrast, in pancreatic acinar cells and mast cells, large granules composed of multiple unit granules permit the cells to store

  5. Lab assessment of Bruce Unit 4 steam generator top-of-tubesheet cracking

    Energy Technology Data Exchange (ETDEWEB)

    Jevec, J.; Sarver, J. [Babcock and Wilcox Research Center (United States); King, P.; Yu, J. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Sedman, K.; Durance, D. [Bruce Power, Tiverton, Ontario (Canada)

    2009-07-01

    An increasing number of significant circumferential indications were detected at the roll transition zone (RTZ) of Bruce Power Unit 4 steam generator (SG) tubing (sensitized Alloy 600) during the 2006 and 2007 Spring outages. Metallurgical examination of removed tubes found significant IGA/SCC associated with these indications. However, no circumferential indications were detected on Unit 4 SG tubing during the subsequent Fall 2007 and Spring 2008 outages. Based on a review of outage layup conditions it was theorized that the observed degradation occurs during an outage when the steam generator is drained for maintenance in combination with the presence of detrimental contaminants such as sulfur and copper. This theory was tested in the laboratory using a series of electrochemical and simulated crevice exposure tests. The oxygen/hydrazine reaction at room temperature and the resultant effect on the electrochemical potential of the sensitized Alloy 600 tubing were also studied in this program. Results from this test program are presented in this paper. The results indicate that exposure of the solutions to air tends to keep the sample in the sludge at a more reducing condition as compared to the free span tubing above the sludge resulting in a larger driving force for corrosion of the sample in the sludge. The theory that the defects in the RTZ were caused during drain-down outage conditions was shown to be plausible. (author)

  6. Dynamic Model for Hydro-Turbine Generator Units Based on a Database Method for Guide Bearings

    Directory of Open Access Journals (Sweden)

    Yong Xu

    2013-01-01

    Full Text Available A suitable dynamic model of rotor system is of great significance not only for supplying knowledge of the fault mechanism, but also for assisting in machine health monitoring research. Many techniques have been developed for properly modeling the radial vibration of large hydro-turbine generator units. However, an applicable dynamic model has not yet been reported in literature due to the complexity of the boundary conditions and exciting forces. In this paper, a finite element (FE rotor dynamic model of radial vibration taking account of operating conditions is proposed. A brief and practical database method is employed to model the guide bearing. Taking advantage of the method, rotating speed and bearing clearance can be considered in the model. A novel algorithm, which can take account of both transient and steady-state analysis, is proposed to solve the model. Dynamic response for rotor model of 125 MW hydro-turbine generator units in Gezhouba Power Station is simulated. Field data from Optimal Maintenance Information System for Hydro power plants (HOMIS are analyzed compared with the simulation. Results illustrate the application value of the model in providing knowledge of the fault mechanism and in failure diagnosis.

  7. ANALISIS KEJADIAN STEAM GENERATOR TUBE RUPTURE (SGTR BERDASARKAN SKENARIO MIHAMA UNIT 2

    Directory of Open Access Journals (Sweden)

    Andi Sofrany Ekariansyah

    2015-03-01

    Full Text Available Pada tanggal 9 Februari 1991, terjadi kecelakaan putusnya pipa pemanas pembangkit uap (Steam Generator Tube Rupture/SGTR pada PLTN Mihama Unit 2. Dari kejadian tersebut, diperoleh catatan sekuensi kecelakaan berupa aktuasi sistem proteksi dan fitur keselamatan terekayasa dalam memitigasi kebocoran dari sistem primer ke sistem sekunder. Urutan sekuensi tersebut kemudian diterapkan pada PWR standar Jepang untuk disimulasikan menggunakan program perhitungan RELAP5/SCDAP/Mod3.2. Tujuannya untuk mengevaluasi konsekuensi yang terjadi bila kecelakaan tersebut terjadi pada PWR standar Jepang. Parameter yang dibandingkan adalah laju alir kebocoran, perubahan tekanan primer dan sekunder dan perubahan level di dalam pressurizer. Hasil simulasi menunjukkan perbedaan lama waktu kejadian SGTR hingga berhentinya kebocoran yang berlangsung lebih pendek pada PWR standar Jepang. Selain itu jumlah pendingin primer yang bocor dan jumlah uap yang terlepas dari MSRV tercatat lebih besar daripada PWR Mihama unit 2. Karakter aliran kebocoran, fluktuasi tekanan primer, dan level pressurizer sedikit berbeda pada tahap-tahap awal kejadian, namun relatif sama pada tahap akhir ketika aliran kebocoran dapat dihentikan. Hasil simulasi juga menunjukkan perlunya tindakan operator secara manual yang ditunjukkan dari isolasi sistem air umpan bantu (AFW pada pembangkit uap yang bocor, aktuasi katup pelepas uap (MSRV pada pembangkit uap yang utuh dan aktuasi auxiliary spray dan power operated relief valve (PORV pada pressurizer untuk mengantisipasi kejadian sebagai bagian dari prosedur operasi darurat. Kata kunci: SGTR, PWR Mihama Unit 2, PWR standar Jepang   On February 9,1991, a Steam Generator Tube Rupture (SGTR took place at the Mihama Unit No. 2. From that event, the accident sequence representing the actuation of protection system and engineered safety feature to mitigate the leak from primary system to secondary system is recorded. That sequence is then applied on the

  8. Inducement of IGA/SCC in Inconel 600 steam generator tubing during unit outages

    Energy Technology Data Exchange (ETDEWEB)

    Durance, D.; Sedman, K. [Bruce Power, Tiverton, Ontario (Canada); Roberts, J. [CANTECH Associates Ltd., Burlington, Ontario (Canada); King, P. [Babcock and Wilcox Canada, Cambridge, Ontario (Canada); Gorman, J. [Dominion Engineering, Reston, VA (United States); Allen, R. [Kinectrics, Inc., Toronto, Ontario (Canada)

    2008-07-01

    The degradation of Unit 4 SG tubing by IGA/SCC has limited both the operating period and end of life predictions for Unit 4 since restart in late 2003. The circumferential IGA/SCC has been most significant in SG4 with substantial increases in both initiation and growth rates from 2005 through the spring of 2007. A detailed review of the occurrence of circumferential OD IGA/SCC at the RTZ in the HL TTS region of Bruce 4 steam generator tubes has led a conclusion that it is probable that the IGA/SCC has been the result of attack by partially reduced sulfur species such as tetrathionates and thiosulfates during periods of low temperature exposure. It is believed that attack of this type has mostly likely occurred during startup evolutions following outages as the result the development of aggressive reduced sulfur species in the TTS region during periods when the boilers were fully drained for maintenance activities. The modification of outage practices to limit secondary side oxygen ingress in the spring of 2007 has apparently arrested the degradation and has had significant affects on the allowable operating interval and end of life predictions for the entire unit. (author)

  9. Multi-Objective Optimization Design for Cooling Unit of Automotive Exhaust-Based Thermoelectric Generators

    Science.gov (United States)

    Qiang, J. W.; Yu, C. G.; Deng, Y. D.; Su, C. Q.; Wang, Y. P.; Yuan, X. H.

    2016-03-01

    In order to improve the performance of cooling units for automotive thermoelectric generators, a study is carried out to optimize the cold side and the fin distributions arranged on its inner faces. Based on the experimental measurements and numerical simulations, a response surface model of different internal structures is built to analyze the heat transfer and pressure drop characteristics of fluid flow in the cooling unit. For the fin distributions, five independent variables including height, length, thickness, space and distance from walls are considered. An experimental study design incorporating the central composite design method is used to assess the influence of fin distributions on the temperature field and the pressure drop in the cooling units. The archive-based micro genetic algorithm (AMGA) is used for multi-objective optimization to analyze the sensitivity of the design variables and to build a database from which to construct the surrogate model. Finally, improvement measures are proposed for optimization of the cooling system and guidelines are provided for future research.

  10. Siddhartha: Domain-specific unit test generation for "low-testibility" programs

    Science.gov (United States)

    Reyes, Arthur Alexander

    This Dissertation validates the hypothesis that domain-specific language (DSL) methodology can provide essential automation support for specification-based testing (SBT) of computer program units expressed in difficult-to-test (i.e., "low-testability"), domain-specific design styles. This Dissertation presents Siddhartha, an extension to DSL methodology for development of program synthesizers to support SBT methods in novel application domains. Synthesizers map formal test data specifications (TestSpecs) into unit test driver procedures (Drivers). Both TestSpecs and Driver reference designs are represented via DSLs. Synthesizer development is iterative and example-driven. A Domain Designer applying the Siddhartha methodology in a novel application domain first selects a collection of general, example TestSpecs, then manually codes a collection of corresponding Drivers. Each Driver is expressed in a different reference design that specifically accommodates difficult-to-test, domain-specific program unit under test (UUT) design styles. After selecting the most promising Driver reference design, the set of (TestSpec, Driver) pairs become test cases for the synthesizer under development. The Domain Designer then designs a TestSpec→Driver translation function. The translation function maps TestSpecs to Driver kernels in the selected reference design. The translation function design simplifies DSL development by modularizing both TestSpec and Driver reference design DSLs into syntactic productions. This effectively optimizes DSL representations to support efficient TestSpec→Driver synthesis. This Dissertation validates the hypothesis by answering the question "What are the relative costs and benefits of applying DSL methods to generate requirements-based and regression Drivers for a flight control system expressed in Ada?" Costs and benefits are measured with respect to manually coded Drivers, which are arguably equivalent to Drivers generated by a general

  11. 77 FR 16278 - License Renewal Application for Indian Point Nuclear Generating Units 2 and 3; Entergy Nuclear...

    Science.gov (United States)

    2012-03-20

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION License Renewal Application for Indian Point Nuclear Generating Units 2 and 3; Entergy Nuclear Operations, Inc. AGENCY: Nuclear Regulatory Commission. ACTION: License renewal application; intent...

  12. High-Frequency Cutoff in Type III Bursts

    Science.gov (United States)

    Stanislavsky, A. A.; Konovalenko, A. A.; Volvach, Ya. S.; Koval, A. A.

    In this article we report about a group of solar bursts with high-frequency cutoff, observed on 19 August of 2012 near 8:23 UT, simultaneously by three different radio telescopes: the Ukrainian decameter radio telescope (8-33 MHz), the French Nancay Decametric Array (10-70 MHz) and the Italian San Vito Solar Observatory of RSTN (25-180 MHz). Morphologically the bursts are very similar to the type III bursts. The solar activity is connected with the emergency of a new group of solar spots on the far side of the Sun with respect to observers on Earth. The solar bursts accompany many moderate flares over eastern limb. The refraction of the behind-limb radio bursts towards the Earth is favorable, if CMEs generate low-density cavities in solar corona.

  13. Clinical use of new-generation pulse oximeters in the neonatal intensive care unit.

    Science.gov (United States)

    Workie, Fegegta A; Rais-Bahrami, K; Short, Billie L

    2005-10-01

    Continuous monitoring by pulse oximetry is a common practice for preterm and critically ill newborns. A new generation of motion-tolerant pulse oximeters have been designed for improved clinical performance with a substantial reduction in alarm frequency. However, little is known about the differences among these new-generation pulse oximeters in the neonatal intensive care unit (NICU). The purpose of this study is to assess the clinical performance of two new-generation pulse oximeters in the NICU. Two new-generation pulse oximeters were used simultaneously to monitor 36 patients in the NICU. The two devices studied were the Philips FAST and the Masimo SET. Patients were randomly assigned for their digit selection and data were collected only when waveforms were of good quality and/or the pulse oximeter's pulse rate (PR) correlated with the electrocardiogram heart rate (HR). The data for oxygen saturation measurements, number of true and false alarms, and number of dropouts as well as the duration of dropouts for each pulse oximeter were recorded by the primary investigator at 5-minute intervals for a period of 2 hours on each patient. Dropouts are instances when the pulse oximeter alarm sounds due to its inability to identify the arterial pulse and provide an oxygen saturation reading. The mean gestational age for the study group was 32 weeks (rang, 24 to 42 weeks). Repeated-measures analysis of variance indicated no difference between the two devices across all time measurements (p=0.357). In addition, paired t-tests for true alarms and false alarms were not significant, with p-values of 0.151 and 0.869, respectively. There was a difference in the number of data dropouts (pMasimo 38). The duration of dropouts was also significant; the Philips device had three times longer duration of dropouts. Physiologic monitoring in the critical care setting requires accurate data measurements. The two new-generation pulse oximeters, the Philips FAST and Masimo SET, are

  14. Accelerated Electromechanical Modeling of a Distributed Internal Combustion Engine Generator Unit

    Directory of Open Access Journals (Sweden)

    Serhiy V. Bozhko

    2012-07-01

    Full Text Available Distributed generation with a combustion engine prime mover is still widely used to supply electric power in a variety of applications. These applications range from backup power supply systems and combined wind-diesel generation to providing power in places where grid connection is either technically impractical or financially uneconomic. Modelling of such systems as a whole is extremely difficult due to the long-time load profiles needed and the computational difficulty of including small time-constant electrical dynamics with large time-constant mechanical dynamics. This paper presents the development of accelerated, reduced-order models of a distributed internal combustions engine generator unit. Overall these models are shown to achieve a massive improvement in the computational time required for long-time simulations while also achieving an extremely high level of dynamic accuracy. It is demonstrated how these models are derived, used and verified against benchmark models created using established techniques. Throughout the paper the modelling set as a whole, including multi level detail, is presented, detailed and finally summarised into a crucial tool for general system investigation and multiple target optimisation.

  15. User-generated online health content: a survey of Internet users in the United Kingdom.

    Science.gov (United States)

    O'Neill, Braden; Ziebland, Sue; Valderas, Jose; Lupiáñez-Villanueva, Francisco

    2014-04-30

    The production of health information has begun to shift from commercial organizations to health care users themselves. People increasingly go online to share their own health and illness experiences and to access information others have posted, but this behavior has not been investigated at a population level in the United Kingdom. This study aims to explore access and production of user-generated health content among UK Internet users and to investigate relationships between frequency of use and other variables. We undertook an online survey of 1000 UK Internet users. Descriptive and multivariate statistical analyses were used to interpret the data. Nearly one-quarter of respondents (23.7%, 237/1000) reported accessing and sharing user-generated health content online, whereas more than 20% (22.2%, 222/1000) were unaware that it was possible to do this. Respondents could be divided into 3 groups based on frequency of use: rare users (78.7%, 612/778) who accessed and shared content less than weekly, users (13.9%, 108/778) who did so weekly, and superusers (7.5%, 58/778) who did so on a daily basis. Superusers were more likely to be male (Ponline health content, only a minority of respondents reported doing so frequently. As this type of content proliferates, superusers are likely to shape the health information that others access. Further research should assess the effect of user-generated online content on health outcomes and use of health services by Internet users.

  16. Mexican Ancestry, Immigrant Generation, and Educational Attainment in the United States

    Directory of Open Access Journals (Sweden)

    Stephen L. Morgan

    2014-09-01

    Full Text Available After introducing alternative perspectives on assimilation and acculturation, we use the 2002-2012 waves of the Education Longitudinal Study to model differences in educational attainment for students sampled as high school sophomores in 2002. We focus on patterns observed for the growing Mexican immigrant population, analyzing separately the trajectories of 1st, 1.5th, 2nd, and 3rd+ generation Mexican immigrant students, in comparison to 3rd+ generation students who self-identify as non-Hispanic whites and students who self-identify as non-Hispanic blacks or African Americans. The results suggest that the dissonant acculturation mechanism associated with the segmented assimilation perspective is mostly unhelpful for explaining patterns of educational attainment, especially for the crucial groups of 1.5th and 2nd generation Mexican immigrant students. Instead, standard measures of family background can account for large portions of group differences in bachelor’s degree attainment, with or without additional adjustments for behavioral commitment to schooling, occupational plans, and educational expectations. The broad structure of inequality in the United States, as well as the rising costs of bachelor’s degrees, should be the primary source of concern when considering the prospects for the incorporation of the children of recent Mexican immigrants into the mainstream.

  17. Short Term Price Forecasting in Electricity Market Considering the Effect of Wind Units\\\\\\' Generation

    Directory of Open Access Journals (Sweden)

    H. Taherian

    2014-05-01

    Full Text Available The price signal in a competitive electricity market has a major importance in all planning and commissioning activities. Also, the electricity price has a non-deterministic nature and is affected by various parameters in short and long terms. Active players in electricity market need accurate and effective price forecasting for risk management. With the increased use of renewable energies, especially wind energy, the electricity price is being affected by this new parameter, as the intermittent nature of wind generation has further complicated the process of instantaneous balancing of power system demand against power generation. In this paper, using the Nord Pool electricity market data, the effect of wind units' generation on price forecasting is studied. The main idea is based on presenting an intelligent model for forecasting the Market Clearing Price through the use of a multilayer perceptron neural network based on hybrid genetic model and Imperialist Competitive algorithm. This hybrid model has a better accuracy, compared to the conventional neural networks (based on gradient-based optimization algorithms, and has the ability of converging towards the absolute optimum. The results verify the high accuracy of this model in short term electricity price forecasting.

  18. Vibration characteristics of a hydraulic generator unit rotor system with parallel misalignment and rub-impact

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhiwei; Zhou, Jianzhong; Yang, Mengqi; Zhang, Yongchuan [Huazhong University of Science and Technology, College of Hydraulic and Digitalization Engineering, Wuhan, Hubei Province (China)

    2011-07-15

    The object of this research aims at the hydraulic generator unit rotor system. According to fault problems of the generator rotor local rubbing caused by the parallel misalignment and mass eccentricity, a dynamic model for the rotor system coupled with misalignment and rub-impact is established. The dynamic behaviors of this system are investigated using numerical integral method, as the parallel misalignment, mass eccentricity and bearing stiffness vary. The nonlinear dynamic responses of the generator rotor and turbine rotor with coupling faults are analyzed by means of bifurcation diagrams, Poincare maps, axis orbits, time histories and amplitude spectrum diagrams. Various nonlinear phenomena in the system, such as periodic, three-periodic and quasi-periodic motions, are studied with the change of the parallel misalignment. The results reveal that vibration characteristics of the rotor system with coupling faults are extremely complex and there are some low frequencies with large amplitude in the 0.3-0.4 x components. As the increase in mass eccentricity, the interval of nonperiodic motions will be continuously moved forward. It suggests that the reduction in mass eccentricity or increase in bearing stiffness could preclude nonlinear vibration. These might provide some important theory references for safety operating and exact identification of the faults in rotating machinery. (orig.)

  19. Mood, anxiety, and personality disorders among first and second-generation immigrants to the United States.

    Science.gov (United States)

    Salas-Wright, Christopher P; Kagotho, Njeri; Vaughn, Michael G

    2014-12-30

    A careful examination of the multigenerational relationship between immigrant status and mental disorders can provide important information about the robustness and nature of the immigrant-mental health link. We examine immigrant status as a protective factor against mental illness, assess intergenerational effects, examine differences across race/ethnicity, and report the prevalence of mood, anxiety, and personality disorders of immigrants across major world regions. We employ data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and compare first (n=5363) and second-generation (n=4826) immigrants from Asia, Africa, Europe, and Latin America to native-born Americans (n=24,461) with respect to mental disorders. First-generation immigrants are significantly less likely than native-born Americans to be diagnosed with a mood, anxiety, or personality disorder, though the prevalence of mental health diagnoses increases among second generation immigrants. Similar results were observed for immigrants from major world regions as the prevalence of psychiatric morbidity was lower among immigrants from Africa, Latin America, Europe, and Asia compared to native-born Americans. Findings provide evidence in support of the notion that the immigrant paradox may be extended to include mood, anxiety, and personality disorders in the United States.

  20. Possible Mechanism for the Generation of a Fundamental Unit of Charge (long version)

    Energy Technology Data Exchange (ETDEWEB)

    Lestone, John Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-16

    Various methods for calculating particle-emission rates from hot systems are reviewed. Semi-classically derived photon-emission rates often contain the term exp(-ε/T) which needs to be replaced with the corresponding Planckian factor of [exp(-ε/T)-1]-1 to obtain the correct rate. This replacement is associated with the existence of stimulated emission. Simple arguments are used to demonstrate that black holes can also undergo stimulated emission, as previously determined by others. We extend these concepts to fundamental particles, and assume they can be stimulated to emit virtual photons with a cross section of πλ2, in the case of an isolated particle when the incident virtual-photon energy is < 2πmc2. Stimulated-virtual photons can be exchanged with other particles generating a force. With the inclusion of near-field effects, the model choices presented give a calculated fundamental unit of charge of 1.6022x10-19 C. If these choices are corroborated by detailed calculations then an understanding of the numerical value of the fine structure constant may emerge. The present study suggests charge might be an emergent property generated by a simple interaction mechanism between point-like particles and the electromagnetic vacuum, similar to the process that generates the Lamb shift.

  1. Comparison of the bonding strengths of second- and third-generation light-emitting diode light-curing units

    Science.gov (United States)

    Lee, Hee-Min; Kim, Sang-Cheol; Kang, Kyung-Hwa

    2016-01-01

    Objective With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. Methods In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers’ instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. Results The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. Conclusions The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit. PMID:27896210

  2. 78 FR 49305 - Luminant Generation Company LLC, Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2...

    Science.gov (United States)

    2013-08-13

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Luminant Generation Company LLC, Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2; Application... Nuclear Power Plant, Unit Nos. 1 and 2, respectively, located in Somervell County, Texas. The...

  3. 78 FR 14361 - In the Matter of Luminant Generation Company LLC, Comanche Peak Nuclear Power Plant, Units 1 and...

    Science.gov (United States)

    2013-03-05

    ... Luminant Generation Company LLC, Comanche Peak Nuclear Power Plant, Units 1 and 2; Order Approving the... authorizes the possession, use, and operation of the Comanche Peak Nuclear Power Plant, Units 1 and 2 (CPNPP... From the Federal Register Online via the Government Publishing Office NUCLEAR...

  4. 75 FR 4426 - Florida Power and Light Company; Turkey Point Nuclear Generating Units 3 and 4; Environmental...

    Science.gov (United States)

    2010-01-27

    ... the beltline region of the Turkey Point Units 3 and 4 reactor pressure vessels. Environmental Impacts... COMMISSION Florida Power and Light Company; Turkey Point Nuclear Generating Units 3 and 4; Environmental..., located in Miami, Florida. In accordance with 10 CFR 51.21, the NRC prepared an environmental assessment...

  5. 75 FR 14211 - Southern California Edison, San Onofre Nuclear Generating Station, Unit 2 and Unit 3; Exemption

    Science.gov (United States)

    2010-03-24

    ... (SONGS), Unit 2 and Unit 3, respectively. The licenses provide, among other things, that the facility is... March 27, 2009 (74 FR 13926), establish and update generically applicable security requirements similar... the June 4, 2009, letter. SONGS Schedule Exemption Request The licensee provided detailed...

  6. 75 FR 71152 - Southern California Edison; San Onofre Nuclear Generating Station, Unit 2 and Unit 3; Exemption

    Science.gov (United States)

    2010-11-22

    ... (SONGS), Unit 2 and Unit 3, respectively. The licenses provide, among other things, that the facility is... March 27, 2009 (74 FR 13926), establish and update generically applicable security requirements similar..., 2009, letter. SONGS Schedule Exemption Request The licensee provided detailed information in...

  7. Optimal Lead-lag Controller for Distributed Generation Unit in Island Mode Using Simulated Annealing

    Directory of Open Access Journals (Sweden)

    A. Akbarimajd

    2014-07-01

    Full Text Available Active and reactive power components of a Distributed Generation (DG is normally controlled by a conventional dq-current control strategy however, after islanding the dq-current which is not able to successfully complete the control task is disabled and a lead-lag control strategy based optimized by simulated annealing is proposed for control of DG unit in islanding mode. Integral of Time multiply by Absolute Error (ITEA criterion is used as cost function of simulated annealing in order to achieve smooth response and robust behavior. The proposed controller improved robust stability margins of the system. Simulations with different load and input operating conditions verify advantages of the proposed controller in comparison with a previously developed classic controller in terms of robustness and response time.

  8. SOFTWARE SOLUTIONS FOR MEASURING AND FORECASTING THE CASH GENERATING UNIT FLOWS RELATED TO INTANGIBLE ASSETS

    Directory of Open Access Journals (Sweden)

    Veronica R GROSU

    2016-08-01

    Full Text Available In light of the difficulties encountered in assessing the value of the CGU (Cash Generating Unit and of the cash flows associated with goodwill or other intangible assets of a company and after performing the impairment test as provided by the IAS 36-Intangibile Asset and the forecasts related to it, the aim of this paper is to identify and suggest software instruments that would assist in the measurement and forecasting of these elements. The employment of the SPSS and the NeuroShell programmes in analyzing and forecasting the changes in CGU and CGU flows has helped compare the results and the ensuing error margins, thus giving the business entity the possibility to select the best software option, depending on certain variables identified on a micro or a macroeconomic level that may affect the depreciation or the increases in value of the underlying assets for CGU or CGU flows.

  9. International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

    Science.gov (United States)

    Erickson, Robert J.; Howe, John, Jr.; Kulp, Galen W.; VanKeuren, Steven P.

    2008-01-01

    The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution.

  10. Conversion of an 800 MW oil fired generating unit to burn Orimulsion

    Energy Technology Data Exchange (ETDEWEB)

    Blum, J.; Halpin, M.; Morgan, D.; Alcantara, J.

    1998-07-01

    Florida Power and Light Company (FPL) is proposing to convert the two existing 800 megawatt (MW) residual oil fired generating units at its Manatee Plant located in Parrish, Florida, to burn Ormulsion. Ormulsion is the registered trademark name for a mixture of water and a naturally occurring heavy hydrocarbon known as bitumen. Orimulsion, which originates in Venezuela, will be shipped to Port Manatee in double-hulled vessels, stored at FPL's existing Port Manatee Terminal, and transported via FPL's existing fuel pipeline to the Manatee Plant. The proposed conversion involves modifications of the existing fuel handling facilities, enhancements of the boiler heat transfer surfaces and soot blowing system, and addition of new pollution control equipment. The Manatee Orimulsion conversion will result in overall environmental benefits and significant savings to FPL's customers. This paper summarizes the overall objectives of the project and briefly describes these modifications.

  11. Conversion of an 800 MW oil fired generating unit to burn Orimulsion

    Energy Technology Data Exchange (ETDEWEB)

    Blum, J.; Halpin, M.; Morgan, D.; Alcantara, J.

    1998-04-01

    Florida Power & Light Company (FPL) is proposing to convert the two existing 800 megawatt (MW) residual oil fired generating units at its Manatee Plant located in Parrish, Florida, to burn Orimulsion. Orimulsion is the registered trademark name for a mixture of water and a naturally occurring heavy hydrocarbon known as bitumen. Orimulsion, which originates in Venezuela, will be shipped to Port Manatee in double-hulled vessels, stored at FPL`s existing Port Manatee Terminal, and transported via FPL`s existing fuel pipeline to the Manatee Plant. The proposed conversion involves modifications of the existing fuel handling facilities, enhancements of the boiler heat transfer surfaces and soot blowing system, and addition of new pollution control equipment. The Manatee Orimulsion conversion will result in overall environmental benefits and significant savings to FPL`s customers. This paper summarizes the overall objectives of the project and briefly describes these modifications.

  12. Determination of Fuel Consumption Indexes of Co-generation Combined Cycle Steam and Gas Units with unfired waste heat boilers

    Directory of Open Access Journals (Sweden)

    S. A. Kachan

    2010-01-01

    Full Text Available The paper presents the developed methodology and the results of determination of fuel consumption indexes of co-generation combined cycle steam and gas units (PGU with unfired waste heat boilers apply to PGU-230 of 3-d co-generation power plant ofMinsk. 

  13. Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

    Directory of Open Access Journals (Sweden)

    Jörg Körner

    2015-12-01

    Full Text Available It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distributions within the burst by pre-shaping the seed pulse burst with a Pockels cell. Furthermore, this technique allows for the precompensation of any static modulations across the burst, which may be introduced during the subsequent amplification process. Therefore, a pulse burst with a uniform energy distribution can also be generated. The method is tested with an ultra-short pulse burst mode laser amplifier system producing bursts of a 1 ms duration with a pulse repetition rate of 1 MHz and a maximum output power of 800 W during the burst. Furthermore, a method to predict the influence of the amplifier on a non-uniformly shaped burst is presented and successfully tested to produce a pre-defined pulse shape after amplification.

  14. Ceruloplasmin decreases respiratory burst reaction during pregnancy.

    Science.gov (United States)

    Varfolomeeva, Elena Y; Semenova, Elena V; Sokolov, Alexey V; Aplin, Kirill D; Timofeeva, Kseniya E; Vasilyev, Vadim B; Filatov, Michael V

    2016-08-01

    Testing of pregnant women reveals weakening of neutrophil-mediated effector functions, such as reactive oxygen species generation. This study provides data confirming the phenomenon, gained through application of the flow cytometry technique. Key factors influencing neutrophil functional activity in blood plasma of pregnant women have not been detected so far. At the same time, concentration of ceruloplasmin - a copper-containing glycoprotein - is known to increase in blood significantly during pregnancy. We observed the negative correlation between ceruloplasmin concentration in blood plasma of pregnant women and the intensity of respiratory burst of neutrophils. Fractionation of plasma using gel-filtration revealed that ceruloplasmin-containing fraction demonstrated suppression of the respiratory burst reaction. Partial elimination of ceruloplasmin from the blood of pregnant women, performed with the help of specific antibodies and followed by immunoprecipitation, leads to an increased respiratory burst reaction. On the contrary, addition of ceruloplasmin to blood samples of healthy donors noticeably decreases the respiratory burst reaction. The results presented prove that change in ceruloplasmin level in plasma is necessary and sufficient for modulating the ability of neutrophils to produce reactive oxygen species during pregnancy.

  15. Acoustic characteristics of bubble bursting at the surface of a high-viscosity liquid

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Bo; Zhang Jian-Run; Li Pu

    2012-01-01

    An acoustic pressure model of bubble bursting is proposed.An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported.It is found that the sudden bursting of a bubble at the high-viscosity liquid surface generates N-shape wave at first,then it transforms into a jet wave.The fundamental frequency of the acoustic signal caused by the bursting bubble decreases linearly as the bubble size increases.The results of the investigation can be used to understand the acoustic characteristics of bubble bursting.

  16. Understanding Neutron Stars using Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, S.

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star = EOS model of high density cold matter in the neutron star cores. Extensive observation and analysis of the data from the rising portions of the bursts = modeling of burst oscillations and thermonuclear flame spreading. Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  17. Neutron Stars and Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, Sudip

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star approaching EOS model of high density cold matter in the neutron star cores. +k Extensive observation and analysis of the data from the rising portions of the bursts - modeling of burst oscillations and thermonuclear flame spreading. +k Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  18. Next-generation sequencing for diagnosis of rare diseases in the neonatal intensive care unit

    Science.gov (United States)

    Daoud, Hussein; Luco, Stephanie M.; Li, Rui; Bareke, Eric; Beaulieu, Chandree; Jarinova, Olga; Carson, Nancy; Nikkel, Sarah M.; Graham, Gail E.; Richer, Julie; Armour, Christine; Bulman, Dennis E.; Chakraborty, Pranesh; Geraghty, Michael; Lines, Matthew A.; Lacaze-Masmonteil, Thierry; Majewski, Jacek; Boycott, Kym M.; Dyment, David A.

    2016-01-01

    Background: Rare diseases often present in the first days and weeks of life and may require complex management in the setting of a neonatal intensive care unit (NICU). Exhaustive consultations and traditional genetic or metabolic investigations are costly and often fail to arrive at a final diagnosis when no recognizable syndrome is suspected. For this pilot project, we assessed the feasibility of next-generation sequencing as a tool to improve the diagnosis of rare diseases in newborns in the NICU. Methods: We retrospectively identified and prospectively recruited newborns and infants admitted to the NICU of the Children’s Hospital of Eastern Ontario and the Ottawa Hospital, General Campus, who had been referred to the medical genetics or metabolics inpatient consult service and had features suggesting an underlying genetic or metabolic condition. DNA from the newborns and parents was enriched for a panel of clinically relevant genes and sequenced on a MiSeq sequencing platform (Illumina Inc.). The data were interpreted with a standard informatics pipeline and reported to care providers, who assessed the importance of genotype–phenotype correlations. Results: Of 20 newborns studied, 8 received a diagnosis on the basis of next-generation sequencing (diagnostic rate 40%). The diagnoses were renal tubular dysgenesis, SCN1A-related encephalopathy syndrome, myotubular myopathy, FTO deficiency syndrome, cranioectodermal dysplasia, congenital myasthenic syndrome, autosomal dominant intellectual disability syndrome type 7 and Denys–Drash syndrome. Interpretation: This pilot study highlighted the potential of next-generation sequencing to deliver molecular diagnoses rapidly with a high success rate. With broader use, this approach has the potential to alter health care delivery in the NICU. PMID:27241786

  19. Climate Change Impacts on Rivers and Implications for Electricity Generation in the United States

    Science.gov (United States)

    Miara, A.; Vorosmarty, C. J.; Macknick, J.; Corsi, F.; Cohen, S. M.; Tidwell, V. C.; Newmark, R. L.; Prousevitch, A.

    2015-12-01

    The contemporary power sector in the United States is heavily reliant on water resources to provide cooling water for thermoelectric generation. Efficient thermoelectric plant operations require large volumes of water at sufficiently cool temperatures for their cooling process. The total amount of water that is withdrawn or consumed for cooling and any potential declines in efficiencies are determined by the sector's fuel mix and cooling technologies. As such, the impact of climate change, and the extent of impact, on the power sector is shaped by the choice of electricity generation technologies that will be built over the coming decades. In this study, we model potential changes in river discharge and temperature in the contiguous US under a set of climate scenarios to year 2050 using the Water Balance Model-Thermoelectric Power and Thermal Pollution Model (WBM-TP2M). Together, these models quantify, in high-resolution (3-min), river temperatures, discharge and power plant efficiency losses associated with changes in available cooling water that incorporates climate, hydrology, river network dynamics and multi-plant impacts, on both single power plant and regional scales. Results are used to assess the aptness and vulnerability of contemporary and alternative electricity generation pathways to changes in climate and water availability for cooling purposes, and the concomitant impacts on power plant operating efficiencies. We assess the potential impacts by comparing six regions (Northeast, Southeast, Midwest, Great Plains, Southwest, Northwest as in the National Climate Assessment (2014)) across the US. These experiments allow us to assess tradeoffs among electricity-water-climate to provide useful insight for decision-makers managing regional power production and aquatic environments.

  20. Substance Use Disorders Among First- and Second-Generation Immigrant Adults in the United States: Evidence of an Immigrant Paradox?

    Science.gov (United States)

    Salas-Wright, Christopher P; Vaughn, Michael G; Clark, Trenette T; Terzis, Lauren D; Córdova, David

    2014-01-01

    Objective: A growing number of studies have examined the “immigrant paradox” with respect to the use of licit and illicit substances in the United States. However, there remains a need for a comprehensive examination of the multigenerational and global links between immigration and substance use disorders among adults in the United States. Method: The present study, using data from the National Epidemiologic Survey on Alcohol and Related Conditions, aimed to address these gaps by comparing the prevalence of substance use disorders of first-generation (n = 3,338) and second-generation (n = 2,515) immigrants with native-born American adults (n = 15,733) in the United States. We also examined the prevalence of substance use disorders among first-generation emigrants from Asia, Africa, Europe, and Latin America in contrast to second-generation and native-born Americans. Results: The prevalence of substance use disorders was highest among native-born Americans, slightly lower among second-generation immigrants, and markedly lower among first-generation immigrants. Adjusted risk ratios were largest among individuals who immigrated during adolescence (ages 12–17 years) and adulthood (age 18 years or older). Results were consistent among emigrants from major world regions. Conclusions: Consistent with a broad body of literature examining the links between the immigrant paradox and health outcomes, results suggest that nativity and age at arrival are significant factors related to substance use disorders among first- and second-generation immigrants in the United States. PMID:25343653

  1. Solar Partial N-burst

    Institute of Scientific and Technical Information of China (English)

    Zong-Jun Ning; Yu-Ying Liu; Qi-Jun Fu; Fu-Ying Xu

    2003-01-01

    We present a new sub-class of type III solar radio burst at the highfrequencies around 6.0 GHz. In addition to a descending and an ascending branchon the dynamic spectrum, it has an inverted morphology different from the simpletype U-burst. We call it "partial N-burst" because it is interpreted as the knownN-burst minus its first branch. The partial N-burst presented here was detectedamong a reverse slope type III (RS-III) burst group prior to the type V solar radiocontinuum and was simultaneously recorded by two spectrometers at the NationalAstronomical Observatories, Chinese Academy of Sciences (NAOC, 5.20-7.60 GHz)and at Purple Mountain Observatory (PMO, 4.50-7.50 GHz) on 1999 August 25.After the N-burst and M-burst, the partial N-burst is a third piece of evidence for amagnetic mirror effect in solar radio observation, when the same electron is reflectedat a pinched foot of a flare loop.

  2. Gamma-ray burst spectra

    Science.gov (United States)

    Teegarden, B. J.

    1982-01-01

    A review of recent results in gamma-ray burst spectroscopy is given. Particular attention is paid to the recent discovery of emission and absorption features in the burst spectra. These lines represent the strongest evidence to date that gamma-ray bursts originate on or near neutron stars. Line parameters give information on the temperature, magnetic field and possibly the gravitational potential of the neutron star. The behavior of the continuum spectrum is also discussed. A remarkably good fit to nearly all bursts is obtained with a thermal-bremsstrahlung-like continuum. Significant evolution is observed of both the continuum and line features within most events.

  3. Determination of ejection velocity of rock fragments during rock burst in consideration of damage

    Institute of Scientific and Technical Information of China (English)

    ZUO Yu-jun; LI Xi-bing; ZHOU Zi-long

    2005-01-01

    The ejection velocity of rock fragments during rock burst, one of the important indexes representing the rock burst strength, is used most conveniently in the supporting design of tunnel with rock burst tendency and is often determined by means of observation devices. In order to calculate the average ejection velocity of rock fragments theoretically, the energy of rock burst was divided into damage consuming energy and kinetic energy gained by unit volume of rock firstly, and then the rock burst kinetic proportional coefficient η was brought up which could be determined according to the rock-burst damage energy index WD , at last the expression of the average ejection velocity of rock fragments during rock burst was obtained and one deep level underground tunnel was researched using the mentioned method. The results show that the calculation method is valid with or without considering the tectonic stress of tunnels, and that the method can be a reference for supporting design of deep mining.

  4. Rock burst laws in deep mines based on combined model of membership function and dominance-based rough set

    Institute of Scientific and Technical Information of China (English)

    刘浪; 陈忠强; 王李管

    2015-01-01

    Rock bursts are spontaneous, violent fracture of rock that can occur in deep mines, and the likelihood of rock bursts occurring increases as depth of the mine increases. Rock bursts are also affected by the compressive strength, tensile strength, tangential strength, elastic energy index, etc. of rock, and the relationship between these factors and rock bursts in deep mines is difficult to analyze from quantitative point. Typical rock burst instances as a sample set were collected, and membership function was introduced to process the discrete values of these factors with the discrete factors as condition attributes and rock burst situations as decision attributes. Dominance-based rough set theory was used to generate preference rules of rock burst, and eventually rock burst laws analysis in deep mines with preference relation was taken. The results show that this model for rock burst laws analysis in deep mines is more reasonable and feasible, and the prediction results are more scientific.

  5. Extracellular calcium modulates persistent sodium current-dependent burst-firing in hippocampal pyramidal neurons.

    Science.gov (United States)

    Su, H; Alroy, G; Kirson, E D; Yaari, Y

    2001-06-15

    The generation of high-frequency spike bursts ("complex spikes"), either spontaneously or in response to depolarizing stimuli applied to the soma, is a notable feature in intracellular recordings from hippocampal CA1 pyramidal cells (PCs) in vivo. There is compelling evidence that the bursts are intrinsically generated by summation of large spike afterdepolarizations (ADPs). Using intracellular recordings in adult rat hippocampal slices, we show that intrinsic burst-firing in CA1 PCs is strongly dependent on the extracellular concentration of Ca(2+) ([Ca(2+)](o)). Thus, lowering [Ca(2+)](o) (by equimolar substitution with Mn(2+) or Mg(2+)) induced intrinsic bursting in nonbursters, whereas raising [Ca(2+)](o) suppressed intrinsic bursting in native bursters. The induction of intrinsic bursting by low [Ca(2+)](o) was associated with enlargement of the spike ADP. Low [Ca(2+)](o)-induced intrinsic bursts and their underlying ADPs were suppressed by drugs that reduce the persistent Na(+) current (I(NaP)), indicating that this current mediates the slow burst depolarization. Blocking Ca(2+)-activated K(+) currents with extracellular Ni(2+) or intracellular chelation of Ca(2+) did not induce intrinsic bursting. This and other evidence suggest that lowering [Ca(2+)](o) may induce intrinsic bursting by augmenting I(NaP). Because repetitive neuronal activity in the hippocampus is associated with marked decreases in [Ca(2+)](o), the regulation of intrinsic bursting by extracellular Ca(2+) may provide a mechanism for preferential recruitment of this firing mode during certain forms of hippocampal activation.

  6. Generation of co-culture spheroids as vascularisation units for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    R Walser

    2013-11-01

    Full Text Available Cell spheroids represent attractive building units for bone tissue engineering, because they provide a three-dimensional environment with intensive direct cell-cell contacts. Moreover, they allow for co-culture of both osteoblasts and vessel-forming cells, which may markedly increase their survival and vascularisation after transplantation. To test this hypothesis, we generated co-culture spheroids by aggregating different combinations of primary human osteoblasts (HOB, human dermal microvascular endothelial cells (HDMEC and normal human dermal fibroblasts (NHDF using the liquid overlay technique. Mono-culture spheroids consisting either of HOB or HDMEC served as controls. After in vitro characterisation, the different spheroids were transplanted into dorsal skinfold chambers of CD1 nu/nu mice to study in vivo their viability and vascularisation over a 2-week observation period by means of repetitive intravital fluorescence microscopy and immunohistochemistry. In vitro, co-culture spheroids containing HDMEC rapidly formed dense tubular vessel-like networks within 72 h and exhibited a significantly decreased rate of apoptotic cell death when compared to mono-culture HDMEC spheroids. After transplantation, these networks interconnected to the host microvasculature by external inosculation. Of interest, this process was most pronounced in HOB-HDMEC spheroids and could not further be improved by the addition of NHDF. Accordingly, HOB-HDMEC spheroids were larger when compared to the other spheroid types. These findings indicate that HOB-HDMEC spheroids exhibit excellent properties to preserve viability and to promote proliferation and vascularisation. Therefore, they may be used as functional vascularisation units in bone tissue engineering for the seeding of scaffolds or for the vitalisation of non-healing large bone defects.

  7. Four Generations of Maintenance Resource Management Programs in the United States: An Analysis of the Past, Present, and Future

    Science.gov (United States)

    Taylor, James C.; Patankar, Manoj S.

    2001-01-01

    This paper analyzes four generations of Maintenance Resource Management (MRM) programs implemented by aviation maintenance organizations in the United States. Data collected from over ten years of survey research and field observations are used for this analysis; they are presented in a case-study format. The first three generations of MRM programs were episodic efforts to increase safety through teamwork, focus group discussions, and awareness courses, respectively. Now, the fourth generation programs, characterized by a commitment to long-term communication and behavioral changes in maintenance, are set to build on those earlier generations, toward a culture of mutual trust between mechanics, their managers, and regulators.

  8. Manifestation of peripherial coding in the effect of increasing loudness and enhanced discrimination of the intensity of tone bursts before and after tone burst noise

    Science.gov (United States)

    Rimskaya-Korsavkova, L. K.

    2017-07-01

    To find the possible reasons for the midlevel elevation of the Weber fraction in intensity discrimination of a tone burst, a comparison was performed for the complementary distributions of spike activity of an ensemble of space nerves, such as the distribution of time instants when spikes occur, the distribution of interspike intervals, and the autocorrelation function. The distribution properties were detected in a poststimulus histogram, an interspike interval histogram, and an autocorrelation histogram—all obtained from the reaction of an ensemble of model space nerves in response to an auditory noise burst-useful tone burst complex. Two configurations were used: in the first, the peak amplitude of the tone burst was varied and the noise amplitude was fixed; in the other, the tone burst amplitude was fixed and the noise amplitude was varied. Noise could precede or follow the tone burst. The noise and tone burst durations, as well as the interval between them, was 4 kHz and corresponded to the characteristic frequencies of the model space nerves. The profiles of all the mentioned histograms had two maxima. The values and the positions of the maxima in the poststimulus histogram corresponded to the amplitudes and mutual time position of the noise and the tone burst. The maximum that occurred in response to the tone burst action could be a basis for the formation of the loudness of the latter (explicit loudness). However, the positions of the maxima in the other two histograms did not depend on the positions of tone bursts and noise in the combinations. The first maximum fell in short intervals and united intervals corresponding to the noise and tone burst durations. The second maximum fell in intervals corresponding to a tone burst delay with respect to noise, and its value was proportional to the noise amplitude or tone burst amplitude that was smaller in the complex. An increase in tone burst or noise amplitudes was caused by nonlinear variations in the two

  9. Dark Gamma Ray Bursts

    CERN Document Server

    Brdar, Vedran; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p-wave process than for s-wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to Standard Model particles later, the annihilation bu...

  10. Powerful Radio Burst Indicates New Astronomical Phenomenon

    Science.gov (United States)

    2007-09-01

    . "It was a bit of luck that the survey included some observations of the sky surrounding the clouds," Narkevic said. It was from those "flanking" observations that the mysterious radio burst appeared in the data. The burst of radio waves was strong by astronomical standards, but lasted less than five milliseconds. The signal was spread out, with higher frequencies arriving at the telescope before the lower frequencies. This effect, called dispersion, is caused by the signal passing through ionized gas in interstellar and intergalactic space. The amount of this dispersion, the astronomers said, indicates that the signal likely originated about three billion light-years from Earth. No previously-detected cosmic radio burst has the same set of characteristics. "This burst represents an entirely new astronomical phenomenon," Bailes said. The astronomers estimate on the basis of their results that hundreds of similar events should occur over the sky each day. "Few radio surveys have the necessary sensitivity to such short-duration bursts, which makes them notoriously difficult to detect with current instruments," added Crawford. The next generation of radio telescopes currently under development should be able to detect many of these bursts across the sky. Although the nature of the mysterious new object is unclear, the astronomers have some ideas of what may cause such a burst. One idea is that it may be part of the energy released when a pair of superdense neutron stars collide and merge. Such an event is thought by some scientists to be the cause of one type of gamma-ray burst, but the only radio emission seen so far from these has been from the long-lived "afterglow" that follows the original burst. Another, more exotic, candidate is a burst of energy from an evaporating black hole. Black holes, concentrations of mass so dense that not even light can escape their powerful gravity, can lose mass and energy through a process proposed by famed British physicist Stephen

  11. Radio fiber bursts and fast magnetoacoustic wave trains

    CERN Document Server

    Karlický, M; Jelínek, P

    2012-01-01

    We present a model for dm-fiber bursts that is based on assuming fast sausage magnetoacoustic wave trains that propagate along a dense vertical filament or current sheet. Eight groups of dm-fiber bursts that were observed during solar flares were selected and analyzed by the wavelet analysis method. To model these fiber bursts we built a semi-empirical model. We also did magnetohydrodynamic simulations of a propagation of the magnetoacoustic wave train in a vertical and gravitationally stratified current sheet. In the wavelet spectra of the fiber bursts computed at different radio frequencies we found the wavelet tadpoles, whose head maxima have the same frequency drift as the drift of fiber bursts. It indicates that the drift of these fiber bursts can be explained by the propagating fast sausage magnetoacoustic wave train. Using new semi-empirical and magnetohydrodynamic models with a simple radio emission model we generated the artificial radio spectra of the fiber bursts, which are similar to the observed ...

  12. NUMERICAL RESEARCH ON WATER GUIDE BEARING OF HYDRO-GENERATOR UNIT USING FINITE VOLUME METHOD

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the consideration of the geometry of tilting pad journal bearing, a new form of the Reynolds equation was derived in this article. The film thickness, the squeeze motion of the journal and the rotation motion of the pad were explicitly contained in the equation. Based on this equation, together with the equilibrium equation of pad pivot, the water guide bearing used in the Gezhouba 10 F hydro-generator unit was numerically researched. The new Reynolds equation for the lubricating film was solved using Finite Volume (FV) discretization, Successive Over-Relaxation (SOR) iteration method and C++ code are included. According to the numerical solution, and the stability of the film and the influences of the film thickness, the journal squeeze effect and the pad rotation effect on film force were discussed. The results indicate that the squeeze effect can not be neglected, although the rotation effect is negligible for both low-speed and high-speed bearings, so the computing time could be greatly reduced.

  13. Role of design complexity in forecasting reliability and availability for electric-power-generating units. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Berkey, D.M.; Balaban, H.S.

    1982-10-01

    This report examines the relationship between design complexity and reliability and availability performance for fossil-fueled electric-power-generating units. Multivariate regression analysis was applied to design complexity and reliability and availability performance data gathered from a representative sample of electric-power-generating units. Twelve predictive relationships or equations were developed as a result of employing this statistical procedure. Each equation was verified and assessed. Guidelines for applying the predictive relationships, including confidence limits, were also developed and are presented in this report. A major result of this examination is a quantitative predictive tool that should be useful to the electric-power industry.

  14. ESTIMATION OF BURSTS LENGTH AND DESIGN OF A FIBER DELAY LINE BASED OBS ROUTER

    Directory of Open Access Journals (Sweden)

    RICHA AWASTHI

    2017-03-01

    Full Text Available The demand for higher bandwidth is increasing day by day and this ever growing demand cannot be catered to with current electronic technology. Thus new communication technology like optical communication needs to be used. In the similar context OBS (optical burst switching is considered as next generation data transfer technology. In OBS information is transmitted in forms of optical bursts of variable lengths. However, contention among the bursts is a major problem in OBS system, and for contention resolution defection routing is mostly preferred. However, deflection routing increases delay. In this paper, it is shown that the arrival of very large bursts is rare event, and for moderate burst length the buffering of contending burst can provide very effective solution. However, in case of arrival of large bursts deflection can be used.

  15. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

    After a short review of gamma ray bursts (GRBs), we discuss the physical implications of strong statistical correlations seen among some of the parameters of short duration bursts (90 < 2 s). Finally, we conclude with a brief sketch of a new unified model for long and short GRBs.

  16. Solar cosmic ray bursts and solar neutrino fluxes

    Science.gov (United States)

    Basilevakaya, G. A.; Nikolsky, S. I.; Stozhkov, Y. I.; Charakhchyan, T. N.

    1985-01-01

    The neutrino flux detected in the C1-Ar experiment seems to respond to the powerful solar cosmic ray bursts. The ground-based detectors, the balloons and the satellites detect about 50% of the bursts of soalr cosmic ray generated on the Sun's visible side. As a rule, such bursts originate from the Western side of the visible solar disk. Since the solar cosmic ray bursts are in opposite phase withthe 11-year galactic cosmic ray cycle which also seems to be reflected by neutrino experiment. The neutrino generation in the bursts will flatten the possible 11-year behavior of the AR-37 production rate, Q, in the Cl-Ar experiment. The detection of solar-flare-generated gamma-quanta with energies above tens of Mev is indicative of the generation of high-energy particles which in turn may produce neutrinos. Thus, the increased Q during the runs, when the flare-generated high energy gamma-quanta have been registered, may be regarded as additional evidence for neutrino geneation in the solar flare processes.

  17. 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.

  18. Bursts de raios gama

    Science.gov (United States)

    Braga, J.

    2003-02-01

    Nos últimos anos, graças principalmente aos dados obtidos pelo Compton Gamma-Ray Observatory e pelo satélite ítalo-holandês BeppoSAX, grandes avanços foram obtidos no nosso conhecimento sobre os fascinantes e enigmáticos fenômenos conhecidos por "bursts"de raios gama. Neste trabalho é feita uma revisão sobre a fenomenologia desses misteriosos objetos e são apresentados os desenvolvimentos recentes nessa área palpitante da astrofísica moderna, ressaltando tanto os resultados observacionais obtidos até o momento quanto os modelos teóricos propostos para explixá-los.

  19. Tool for Generation of MAC/GMC Representative Unit Cell for CMC/PMC Analysis

    Science.gov (United States)

    Murthy, Pappu L. N.; Pineda, Evan J.

    2016-01-01

    This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) 4.0. This tool is especially useful in analyzing ceramic matrix composites (CMCs), where higher fidelity with improved accuracy of local response is needed. The tool, however, can be used for analyzing polymer matrix composites (PMCs) as well. MAC/GMC 4.0 is a composite material and laminate analysis software developed at NASA Glenn Research Center. The software package has been built around the concept of the generalized method of cells (GMC). The computer code is developed with a user friendly framework, along with a library of local inelastic, damage, and failure models. Further, application of simulated thermomechanical loading, generation of output results, and selection of architectures to represent the composite material have been automated to increase the user friendliness, as well as to make it more robust in terms of input preparation and code execution. Finally, classical lamination theory has been implemented within the software, wherein GMC is used to model the composite material response of each ply. Thus, the full range of GMC composite material capabilities is available for analysis of arbitrary laminate configurations as well. The primary focus of the current effort is to provide a graphical user interface (GUI) capability that generates a number of different user-defined repeating unit cells (RUCs). In addition, the code has provisions for generation of a MAC/GMC-compatible input text file that can be merged with any MAC/GMC input file tailored to analyze composite materials. Although the primary intention was to address the three different constituents and phases that are usually present in CMCs-namely, fibers, matrix, and interphase-it can be easily modified to address two-phase polymer matrix composite (PMC) materials where an interphase is absent. Currently, the

  20. Quantum Key Based Burst Confidentiality in Optical Burst Switched Networks

    Directory of Open Access Journals (Sweden)

    A. M. Balamurugan

    2014-01-01

    Full Text Available The optical burst switching (OBS is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS. This paper deals with employing RC4 (stream cipher to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks.

  1. Quantum key based burst confidentiality in optical burst switched networks.

    Science.gov (United States)

    Balamurugan, A M; Sivasubramanian, A

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS). This paper deals with employing RC4 (stream cipher) to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks.

  2. Self-similar traffic analysis in optical burst assembly

    Institute of Scientific and Technical Information of China (English)

    Sui Zhicheng; Zeng Qingji; Xiao Shilin

    2005-01-01

    This paper investigates the traffic properties before and after assembly at edge node of Ethernet over optical burst switching (OBS) network for the first time. Burst and inter-arrival time distributions are simulated under time-based and length-based assembly schemes. Self-similar traffic Hurst parameter is compared through R/S and V/T plot. Finally three self-similar traffic generating methods are given. Simulation results demonstrate that, multi-source traffic increases self-similar degree, however after assembly, time-based scheme can decrease self-similar degree, and aggregated burst size is close to Gaussian distribution. Length-based method has no effects on the self-similarity of input traffic. RMD is fit for study of burst network with large self-similarity.

  3. The technology of the bearings used in the nuclear power generation system turbine generator units; Technologie des paliers equipant les groupes turbo-alternateurs du parc nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Vialettes, J.M.; Rossato, M. [Service Ensembles de Production, Departement Machines, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)

    1997-01-01

    A bearing consists of all the stationary part which allow the relative motion in rotation or in translation, of a shaft line. Inside the bearing there is a journal bearing with a metallic anti-friction coating (the babbitt metal). The high power turbine generator unit rotors are supported by smooth transversal journal bearings fed with oil which fills the empty space and runs along the shaft. The technologies used for the bearings and the thrust bearings of the turbine generator units and the various shaft lines of the French CP0/CP1- and CP2/1300 MW-type nuclear power plants are described. The experience feedback is then discussed in terms of the dynamics of the shaft line, i.e. vibrational problems, the influence of the alignment and the babbitt metal incidents. (author) 4 refs., 11 figs.

  4. Observing a Burst with Sunglasses

    Science.gov (United States)

    2003-11-01

    polarisation properties of the afterglow of GRB 030329 as it developed after the explosion. Hypernovae, the source of GRBs, are indeed so far away that they can only be seen as unresolved points of light. To probe their spatial structure, astronomers have thus to rely on a trick: polarimetry (see ESO PR 23/03). Polarimetry works as follows: light is composed of electromagnetic waves which oscillate in certain directions (planes). Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflecting off a pond. The radiation in a gamma-ray burst is generated in an ordered magnetic field, as so-called synchrotron radiation [3]. If the hypernova is spherically symmetric, all orientations of the electromagnetic waves will be present equally and will average out, so there will be no net polarisation. If, however, the gas is not ejected symmetrically, but into a jet, a slight net polarisation will be imprinted on the light. This net polarisation will change with time since the opening angle of the jet widens with time, and we see a different fraction of the emission cone. Studying the polarisation properties of the afterglow of a gamma-ray burst thus allows to gain knowledge about the underlying spatial structures and the strength and orientation of the magnetic field in the region where the radiation is generated. " And doing this over a long period of time, as the afterglow fades and evolves, provides us with a unique diagnostic tool for gamma-ray burst studies ", says Jochen Greiner . Although previous single measurements of the polarisation of GRB's optical afterglow exist, no detailed study has ever been done of the evolution of polarisation with time. This is indeed a very demanding task, only possible with an extremely stable instrument on the largest telescope... and a sufficient bright optical afterglow. As soon as GRB 030329 was detected, the team of

  5. On the Complex Oscillation of Differential Polynomials Generated by Meromorphic Solutions of Differential Equations in the Unit Disc

    Indian Academy of Sciences (India)

    Ting-Bin Cao; Hong-Yan Xu; Chuan-Xi Zhu

    2010-09-01

    In this paper, we investigate the complex oscillation of differential polynomials generated by meromorphic solutions of differential equations $$f^{(k)}+A(z)f=0,\\quad k≥ 2,$$ where the coefficient is meromorphic in the unit disc $\\mathbb{D}=\\{z:|z| < 1\\}$.

  6. 78 FR 45987 - Vogtle Electric Generating Station, Units 3 and 4; Southern Nuclear Operating Company; Change to...

    Science.gov (United States)

    2013-07-30

    ... COMMISSION Vogtle Electric Generating Station, Units 3 and 4; Southern Nuclear Operating Company; Change to... COLs were issued to Southern Nuclear Operating Company, Inc., and Georgia Power Company, Oglethorpe... Search.'' For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff...

  7. 78 FR 45989 - Vogtle Electric Generating Station, Units 3 and 4; Southern Nuclear Operating Company; Change to...

    Science.gov (United States)

    2013-07-30

    ... COMMISSION Vogtle Electric Generating Station, Units 3 and 4; Southern Nuclear Operating Company; Change to... COLs were issued to Southern Nuclear Operating Company, Inc., and Georgia Power Company, Oglethorpe..., select ``ADAMS Public Documents'' and then select ``Begin Web-based ADAMS Search.'' For problems...

  8. Reinforcement Learning Approach to Generate Goal-directed Locomotion of a Snake-Like Robot with Screw-Drive Units

    DEFF Research Database (Denmark)

    Chatterjee, Sromona; Nachstedt, Timo; Tamosiunaite, Minija

    2014-01-01

    Abstract—In this paper we apply a policy improvement algorithm called Policy Improvement using Path Integrals (PI2) to generate goal-directed locomotion of a complex snake-like robot with screw-drive units. PI2 is numerically simple and has an ability to deal with high dimensional systems. Here...

  9. 77 FR 49463 - Southern California Edison, San Onofre Nuclear Generating Station, Units 2 and 3; Application and...

    Science.gov (United States)

    2012-08-16

    ... Edison Company (SCE, the licensee) for operation of the San Onofre Nuclear Generating Station (SONGS... request (LAR) for SONGS, Units 2 and 3, dated July 29, 2011, requesting approval to convert the Current... Technical Specifications (STS) for Combustion Engineering Plants, NUREG-1432. In 1996, SONGS was the...

  10. Autonomous control of inverter-interfaced Distributed Generation units for harmonic current filtering and resonance damping in an islanded microgrid

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    Harmonic current filtering and resonance damping have become important concerns on the control of an islanded microgrids. To address these challenges, this paper proposes a control method of inverter-interfaced Distributed Generation (DG) units, which can autonomously share harmonic currents and ...

  11. Autonomous Control of Inverter-Interfaced Distributed Generation Units for Harmonic Current Filtering and Resonance Damping in an Islanded Microgrid

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2014-01-01

    Harmonic current filtering and resonance damping have become important concerns in the operation and control of the islanded microgrids. To address these challenges, this paper proposes a control method for the inverter-interfaced Distributed Generation (DG) units, which can autonomously share th...

  12. 78 FR 79709 - Duke Energy Florida, Inc., Crystal River Unit 3 Nuclear Generating Plant Post-Shutdown...

    Science.gov (United States)

    2013-12-31

    ...] [FR Doc No: 2013-31317] NUCLEAR REGULATORY COMMISSION [Docket No. 50-302; NRC-2013-0283] Duke Energy Florida, Inc., Crystal River Unit 3 Nuclear Generating Plant Post-Shutdown Decommissioning Activities Report AGENCY: Nuclear Regulatory Commission (NRC). ACTION: Notice of receipt; availability; public...

  13. 76 FR 29277 - Exelon Generation Company, LLC; Peach Bottom Atomic Power Station Unit Nos. 2 and 3...

    Science.gov (United States)

    2011-05-20

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY... Assessment and Finding of No Significant Impact The U.S. Nuclear Regulatory Commission (NRC) is considering... waste (LLRW), from Exelon's Limerick Generating Station, Units 1 and 2 (LGS). The LLRW will be stored in...

  14. Decameter type III bursts with positive and negative frequency drift rates

    Science.gov (United States)

    Melnik, V. N.; Brazhenko, A. I.; Konovalenko, A. A.; Briand, C.; Dorovskyy, V. V.; Zarka, P.; Frantzusenko, A. V.; Rucker, H. O.; Rutkevych, B. P.; Panchenko, M.; Zaqarashvili, T.; Shergelashvili, B.

    2013-09-01

    We report about observations of decameter type III bursts whose frequency drift rates vary their signs from negative to positive. Moreover drift rates of some bursts vary the sign some times. Positive drift rates for some bursts are changed from 0.44 MHz/s to 12 MHz/s. At the same time the negative drift rates of these bursts are standard values for decameter type III bursts. A possible interpretation of such phenomenon on the base of plasma mechanism of type III burst generation is discussed. The sense of this interpretation is that group velocity of type III electromagnetic waves generated by fast electrons at some conditions can be smaller than velocity of these electrons.

  15. Application of Super-Synchronization Speed Control Technology in Two 80 MVA Motor-Generator Units of HL-2A

    Science.gov (United States)

    Li, Huajun; Du, Chang; Xuan, Weiming; Pen, Jianfei; Hu, Haotian; Liu, Lin; Kang, Li; Xu, Lirong; Huang, Zhaorong; Wang, Fen; Wang, Xiaoping

    2007-04-01

    Two sets of super-synchronization speed control assemblies for two 80 MVA motor-generator units have been developed successfully in order to satisfy the demand of the toroidal field system in the HL-2A tokamak. Based on the three-phase logical no-circumfluence a.c./a.c. cycloconverter, the speeds of two 2500 kW double fed drive motors have been regulated by means of the vector control technology. The maximum operating speed of each motor- generator unit has been raised from 1488 rpm (revolutions per minute) to 1650 rpm and the released energy of each unit during a pulsed discharge can reach 500 MJ. As a result, the toroidal field system has the capacity to provide 2.8 tesla (T) in HL-2A experiments.

  16. Effect of deflecting ring on noise generated by outdoor set of a split-unit air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Junwei; Ding, Guoliang [Institute of Refrigeration and Cryogenics, Shanghai JiaoTong University, Shanghai 200030 (China)

    2006-05-15

    In order to analyze the influence of the deflecting ring on the noise generated by the outdoor set of a split-unit air conditioner, the flow field in the outdoor set is simulated with the CFD software STAR-CD, the relative turbulent intensities are computed and the influence of the width and contoured duct of the deflecting ring on the noise generated by the outdoor set is analyzed. The results of computation and experiment show that there is an optimal width of the deflecting ring, corresponding to the minimum noise generated by the outdoor set. In addition, the influence of the contoured duct of the deflecting ring on the noise generated by the outdoor set is analyzed and a double contoured duct is designed. The results of computation and experiment verify that the deflecting ring with double contoured duct can improve the aerodynamic performance and reduce the noise generated by the outdoor set. (author)

  17. The GLAST Burst Monitor (GBM)

    OpenAIRE

    Lichti, G. G.; Briggs, M.S.; Diehl, R.; Fishman, G.; Georgii, R.; Kippen, R. M.; Kouveliotou, C.; Meegan, C.; Paciesas, W.; Preece, R.; Schoenfelder, V.; von Kienlin, A.

    2001-01-01

    The selection of the GLAST burst monitor (GBM) by NASA will allow the investigation of the relation between the keV and the MeV-GeV emission from gamma-ray bursts. The GBM consists of 12 NaI and 2 BGO crystals allowing a continuous measurement of the energy spectra of gamma-ray bursts from ~5 keV to \\~30 MeV. One feature of the GBM is its high time resolution for time-resolved gamma-ray spectroscopy. Moreover the arrangement of the NaI crystals allows a rapid on-board location (

  18. Concept for LEU Burst Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kimpland, Robert Herbert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-07

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

  19. Interim report on the performance of 400-megawatt and larger nuclear and coal-fired generating units: performance through 1976

    Energy Technology Data Exchange (ETDEWEB)

    1979-11-01

    This report is an update of DOE/ERA-0007, Interim Report on the Performance of 400 Megawatt and Larger Nuclear and Coal-Fired Generating Units - Performance Through 1975. The most recent EEI data for nuclear units and for coal units less than 600 MW(e) and having at least one full year of commercial operation are included in this analysis. The analyses cover the following: coal and nuclear units, 400-MW nameplate and larger; historical data through 1976; four industry-recognized performance indices (capacity factor, availability factor, equivalent availability, and forced outage rate); four types of geographical analysis (national, individual, individual utilities, and individual utilities by states); and rankings of states and utilities by performance indices. (MCW)

  20. Identifying crucial parameter correlations maintaining bursting activity.

    Directory of Open Access Journals (Sweden)

    Anca Doloc-Mihu

    2014-06-01

    Full Text Available Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA to each of these four groups. PCA identified a set of three maximal conductances (leak current, [Formula: see text]Leak; a persistent K current, [Formula: see text]K2; and of a persistent Na+ current, [Formula: see text]P that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of [Formula: see text]Leak, [Formula: see text]K2, and [Formula: see text]P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained.

  1. Gamma-Ray Bursts Above 1 GeV

    CERN Document Server

    Baring, M G

    1997-01-01

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between sou...

  2. Observation of a Metric Type N Solar Radio Burst

    CERN Document Server

    Kong, Xiangliang; Feng, Shiwei; Du, Guohui; Li, Chuanyang; Koval, Artem; Vasanth, V; Wang, Bing; Guo, Fan; Li, Gang

    2016-01-01

    Type III and type-III-like radio bursts are produced by energetic electron beams guided along coronal magnetic fields. As a variant of type III bursts, Type N bursts appear as the letter "N" in the radio dynamic spectrum and reveal a magnetic mirror effect in coronal loops. Here, we report a well-observed N-shaped burst consisting of three successive branches at metric wavelength with both fundamental and harmonic components and a high brightness temperature ($>$10$^9$ K). We verify the burst as a true type N burst generated by the same electron beam from three aspects of the data. First, durations of the three branches at a given frequency increase gradually, may due to the dispersion of the beam along its path. Second, the flare site, as the only possible source of non-thermal electrons, is near the western feet of large-scale closed loops. Third, the first branch and the following two branches are localized at different legs of the loops with opposite sense of polarization. We also find that the sense of p...

  3. 30 CFR 57.3461 - Rock bursts.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  4. Types and analysis of defects in welding junctions of the header to steam generator shells on power-generating units with VVER-1000

    Science.gov (United States)

    Ozhigov, L. S.; Voevodin, V. N.; Mitrofanov, A. S.; Vasilenko, R. L.

    2016-10-01

    Investigation objects were metal templates, which were cut during the repair of welding junction no. 111 (header to the steam generator shell) on a power-generating unit with VVER-1000 of the South-Ukraine NPP, and substances of mud depositions collected from walls of this junction. Investigations were carried out using metallography, optical microscopy, and scanning electron microscopy with energy dispersion microanalysis by an MMO-1600-AT metallurgical microscope and a JEOL JSM-7001F scanning electron microscope with the Shottky cathode. As a result of investigations in corrosion pits and mud depositions in the area of welding junction no. 111, iron and copper-enriched particles were revealed. It is shown that, when contacting with the steel header surface, these particles can form microgalvanic cells causing reactions of iron dissolution and the pit corrosion of metal. Nearby corrosion pits in metal are microcracks, which can be effect of the stress state of metal under corrosion pits along with revealed effects of twinning. The hypothesis is expressed that pitting corrosion of metal occurred during the first operation period of the power-generating unit in the ammonia water chemistry conditions (WCC). The formation of corrosion pits and nucleating cracks from them was stopped with the further operation under morpholine WCC. The absence of macrocracks in metal of templates verifies that, during operation, welding junction no. 111 operated under load conditions not exceeding the permissible ones by design requirements. The durability of the welding junction of the header to the steam generator shell significantly depends on the technological schedule of chemical cleaning and steam generator shut-down cooling.

  5. Gamma-ray burst models.

    Science.gov (United States)

    King, Andrew

    2007-05-15

    I consider various possibilities for making gamma-ray bursts, particularly from close binaries. In addition to the much-studied neutron star+neutron star and black hole+neutron star cases usually considered good candidates for short-duration bursts, there are also other possibilities. In particular, neutron star+massive white dwarf has several desirable features. These systems are likely to produce long-duration gamma-ray bursts (GRBs), in some cases definitely without an accompanying supernova, as observed recently. This class of burst would have a strong correlation with star formation and occur close to the host galaxy. However, rare members of the class need not be near star-forming regions and could have any type of host galaxy. Thus, a long-duration burst far from any star-forming region would also be a signature of this class. Estimates based on the existence of a known progenitor suggest that this type of GRB may be quite common, in agreement with the fact that the absence of a supernova can only be established in nearby bursts.

  6. Dynamics Analysis and Transition Mechanism of Bursting Calcium Oscillations in Non-Excitable Cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; LU Qi-Shao; DUAN Li-Xia

    2007-01-01

    A one-pool model with Ca2+-activated inositol-trisphosphate-concentration degradation is considered.For complex bursting Ca2+ oscillation,point-cycle bursting of subHopf-subHopf type is found to be in the intermediate state from quasi-periodic bursting to Point-point bursting of subHopf-subHopf type.The fast-slow burster analysis is used to study the transition mechanisms among simple periodic oscillation,quasi-periodic bursting,point-point and point-cycle burstings.The dynamics analysis of different oscillations provides better insight into the generation and transition mechanisms of complex intra- and inter-cellular Ca2+signalling.

  7. Morphological topology generation of a digital fluid power displacement unit using Chebychev-Grübler-Kutzbach constraint

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.

    2015-01-01

    piston topologies. The morphological approach is combined with the Chebychev- Grübler-Kutzbach criterion, a fully rotatable shaft condition and a straight line path generation condition in order to obtain one degree of freedom single closed chain mechanisms applicable for wind turbines and wave energy...... converters. In conclusion it follows, that six single closed chain planar, one degree of freedom, mechanisms are suitable for digital fluid power displacement units in wind and wave energy applications....

  8. Developing the concept of maintenance and repairs in projects of power units for new-generation nuclear power stations

    Science.gov (United States)

    Gurinovich, V. D.; Yanchenko, Yu. A.

    2012-05-01

    Results from conceptual elaboration of individual requirements for the system of maintenance and repairs that must be implemented in the projects of new-generation nuclear power stations are presented taking as an example the power unit project for a nuclear power station equipped with a standard optimized VVER reactor with enhanced information support (the so-called VVER TOI reactor). Implementation of these concepts will help to achieve competitiveness of such nuclear power stations in the domestic and international markets.

  9. $\\gamma$-ray bursts as the birth-cries of black holes

    CERN Document Server

    Joshi, P; Maartens, R; Joshi, Pankaj; Dadhich, Naresh; Maartens, Roy

    2000-01-01

    The origin of cosmic gamma-ray bursts remains one of the most intriguing puzzles in astronomy. We suggest that purely general relativistic effects in the collapse of massive stars could account for these bursts. The late formation of closed trapped surfaces can occur naturally, allowing the escape of huge energy from curvature-generated fireballs, before these are hidden within a black hole.

  10. Dendritic calcium activity precedes inspiratory bursts in preBotzinger complex neurons

    DEFF Research Database (Denmark)

    Del Negro, Christopher A; Hayes, John A; Rekling, Jens C

    2011-01-01

    to evoke a Ca(2+)-activated inward current that contributes to inspiratory burst generation. We measured Ca(2+) transients by two-photon imaging dendrites while recording neuronal somata electrophysiologically. Dendritic Ca(2+) accumulation frequently precedes inspiratory bursts, particularly at recording...

  11. Application of Super-Synchronization Speed Control Technology in Two 80 MVA Motor-Generator Units of HL-2A

    Institute of Scientific and Technical Information of China (English)

    LI Huajun; WANG Fen; WANG Xiaoping; DU Chang; XUAN Weiming; PEN Jianfei; HU Haotian; LIU Lin; KANG Li; XU Lirong; HUANG Zhaorong

    2007-01-01

    Two sets of super-synchronization speed control assemblies for two 80 MVA motorgenerator units have been developed successfully in order to satisfy the demand of the toroidal field system in the HL-2A tokamak.Based on the three-phase logical no-circumfluence a.c./a.c.cycloconverter,the speeds of two 2500 kW double fed drive motors have been regulated by means of the vector control technology.The maximum operating speed of each motor- generator unit has been raised from 1488 rpm (revolutions per minute) to 1650 rpm and the released energy of each unit during a pulsed discharge can reach 500 MJ.As a result,the toroidal field system has the capacity to provide 2.8 tesla (T) in HL-2A experiments.

  12. Nutrient generation at dairies and feedlots in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of nitrogen and phosphorus generated by cattle at dairies and feedlots...

  13. Availability of own electricity generation in processing units of small wood

    Directory of Open Access Journals (Sweden)

    R. M. Nogueira

    2014-03-01

    Full Text Available The self power generation can be an alternative, to the industries, in view of the low quality of energy supply by conventional network, especially in industries that generate waste with energy potential. Thus, the objective of this study was to compare, economically, self power generating using wood waste as fuel, with the receipt of electricity by conventional network in a small timber industry. It was determined the values of energy consumption by each equipment that is a part of industry and, based on encountered values, it was determined the actual cost of its generation, comparing its values with the prices of energy by conventional network. Based on these results can be noted that the purchase of electricity by conventional network is the most economically advantageous when compared with self power generation under the conditions studied in this work, however, even with the economic advantage of obtaining energy from the network, the generation itself becomes a sustainable alternative from the environmental and social standpoint.

  14. Ethnic Identity Development in Schools among First Generation Immigrants in the United States

    Science.gov (United States)

    Acar, Erkan; Yigit, Mehmet Fatih; Aslan, Dolgun

    2016-01-01

    Today, Americans are increasingly concerned about the matter of immigration in the United States. A growing number believe that immigrants are a burden to the country, taking jobs and housing and creating strains on the health care system. Many Americans are also worried about the cultural impact of the expanding number of newcomers to the U.S.…

  15. Dynamic Agricultural Land Unit Profile Database Generation using Landsat Time Series Images

    Science.gov (United States)

    Torres-Rua, A. F.; McKee, M.

    2012-12-01

    Agriculture requires continuous supply of inputs to production, while providing final or intermediate outputs or products (food, forage, industrial uses, etc.). Government and other economic agents are interested in the continuity of this process and make decisions based on the available information about current conditions within the agriculture area. From a government point of view, it is important that the input-output chain in agriculture for a given area be enhanced in time, while any possible abrupt disruption be minimized or be constrained within the variation tolerance of the input-output chain. The stability of the exchange of inputs and outputs becomes of even more important in disaster-affected zones, where government programs will look for restoring the area to equal or enhanced social and economical conditions before the occurrence of the disaster. From an economical perspective, potential and existing input providers require up-to-date, precise information of the agriculture area to determine present and future inputs and stock amounts. From another side, agriculture output acquirers might want to apply their own criteria to sort out present and future providers (farmers or irrigators) based on the management done during the irrigation season. In the last 20 years geospatial information has become available for large areas in the globe, providing accurate, unbiased historical records of actual agriculture conditions at individual land units for small and large agricultural areas. This data, adequately processed and stored in any database format, can provide invaluable information for government and economic interests. Despite the availability of the geospatial imagery records, limited or no geospatial-based information about past and current farming conditions at the level of individual land units exists for many agricultural areas in the world. The absence of this information challenges the work of policy makers to evaluate previous or current

  16. The Mature Imagination and Consumption Strategies: Age & Generation in the Development of a United Kingdom Baby Boomer Identity

    Directory of Open Access Journals (Sweden)

    Simon Biggs

    2008-04-01

    Full Text Available Baby boomers have been credited with an essentially ‘youthful’ approach to themselves, to consumption and to life-style. As they enter midlife and older age they are also faced with the challenges of a mature identity. This paper critically examines the strategies that baby boomers in the United Kingdom use to manage identity as they grow older. Specifically, questions concerning attitudes to cohort labels, personal ageing and other generations are compared to the consumption choices that are made in areas considered to be key to an ageing identity, including: appearance, clothing and bodily maintenance. Boomers identify with succeeding rather than preceding generations. While they claim not to be concerned with bodily ageing as such, their strategies are aimed at maintaining a balance between youthful and mature identities. Priority was given to blurring the boundaries between themselves and younger adult generations. The implications for the relationship between adult ageing and patterns of consumption are explored.

  17. Broadband Spectral Study of Magnetar Bursts

    Science.gov (United States)

    Kirmizibayrak, Demet; Gogus, Ersin; Sasmaz Mus, Sinem; Kaneko, Yuki

    2016-07-01

    Magnetar bursts occur sporadically on random occasions, and every burst-active episode carries unique information about the bursting magnetar. Therefore, in-depth spectral and temporal analyses of each of the magnetar bursts provide new insights into the bursting and radiation mechanisms. There have been a number of studies over the last decade, investigating the spectral and temporal properties of magnetar bursts. The spectra of typical magnetar bursts were generally described with the Comptonized model or the sum of two blackbody functions. However, it was recently shown that the actual spectral nature of these bursts can be conclusively determined if the spectral analysis is performed on a wide energy coverage. We present the results of in-depth systematic broadband (2 - 250 keV) spectral analysis of a large number of bursts originated from three magnetars: SGR 1806-20, SGR 1900+14, and SGR J1550-5418, observed with the Rossi X-ray Timing Explorer.

  18. Amplitude-Modulated Bursting: A Novel Class of Bursting Rhythms

    Science.gov (United States)

    Vo, Theodore; Kramer, Mark A.; Kaper, Tasso J.

    2016-12-01

    We report on the discovery of a novel class of bursting rhythms, called amplitude-modulated bursting (AMB), in a model for intracellular calcium dynamics. We find that these rhythms are robust and exist on open parameter sets. We develop a new mathematical framework with broad applicability to detect, classify, and rigorously analyze AMB. Here we illustrate this framework in the context of AMB in a model of intracellular calcium dynamics. In the process, we discover a novel family of singularities, called toral folded singularities, which are the organizing centers for the amplitude modulation and exist generically in slow-fast systems with two or more slow variables.

  19. Investigation of a catalytic gas generator for the Space Shuttle APU. [hydrazine Auxiliary Propulsion Unit

    Science.gov (United States)

    Emmons, D. L.; Huxtable, D. D.; Blevins, D. R.

    1974-01-01

    An investigation was conducted to establish the capability of a monopropellant hydrazine catalytic gas generator to meet the requirements specified for the Space Shuttle APU. Detailed analytical and experimental studies were conducted on potential problem areas including long-term nitriding effects on materials, design variables affecting catalyst life, vehicle vibration effects, and catalyst oxidation/contamination. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The objective of the first test series was to demonstrate the capability of the gas generator to successfully complete 20 simulated Space Shuttle missions in steady-state operation. The gas generator was then refurbished and subjected to a second series of tests to demonstrate the pulse-mode capability of the gas generator during 20 simulated missions. The third series of tests was conducted with a refurbished reactor to further demonstrate pulse-mode capability with a modified catalyst bed.

  20. Nonlinear electronic circuit with neuron like bursting and spiking dynamics.

    Science.gov (United States)

    Savino, Guillermo V; Formigli, Carlos M

    2009-07-01

    It is difficult to design electronic nonlinear devices capable of reproducing complex oscillations because of the lack of general constructive rules, and because of stability problems related to the dynamical robustness of the circuits. This is particularly true for current analog electronic circuits that implement mathematical models of bursting and spiking neurons. Here we describe a novel, four-dimensional and dynamically robust nonlinear analog electronic circuit that is intrinsic excitable, and that displays frequency adaptation bursting and spiking oscillations. Despite differences from the classical Hodgkin-Huxley (HH) neuron model, its bifurcation sequences and dynamical properties are preserved, validating the circuit as a neuron model. The circuit's performance is based on a nonlinear interaction of fast-slow circuit blocks that can be clearly dissected, elucidating burst's starting, sustaining and stopping mechanisms, which may also operate in real neurons. Our analog circuit unit is easily linked and may be useful in building networks that perform in real-time.

  1. EDGE: explorer of diffuse emission and gamma-ray burst

    NARCIS (Netherlands)

    Piro, L.; den Herder, J.W.A.; Hermsen, W.; Hoevers, H.F.C.; in 't Zand, J.J.M.; Méndez, M.; Vink, J.

    2008-01-01

    How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysical cosmology. EDGE (Piro et al., 2007) will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions,

  2. Generator, mechanical, smoke: For dual-purpose unit, XM56, Yuma Proving Ground, Yuma, Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Driver, C.J.; Ligotke, M.W.; Moore, E.B. Jr. (Pacific Northwest Lab., Richland, WA (United States)); Bowers, J.F. (Dugway Proving Ground, UT (United States))

    1991-10-01

    The US Army Chemical Research, Development and Engineering Center (CRDEC) is planning to perform a field test of the XM56 smoke generator at the US Army Yuma Proving Ground (YPG), Arizona. The XM56, enabling the use of fog oil in combination with other materials, such as graphite flakes, is part of an effort to improve the efficiency of smoke generation and to extend the effectiveness of the resulting obscurant cloud to include the infrared spectrum. The plan field operation includes a road test and concurrent smoke- generation trials. Three M1037 vehicles with operation XM56 generators will be road-tested for 100 h. Smoke will be generated for 30 min from a single stationary XM56 four times during the road test, resulting in a total of 120 min of smoke generation. The total aerial release of obscurant materials during this test is expected to be 556 kg (1,220 lb) of fog oil and 547 kg (1,200 lb) of graphite flakes. This environmental assessment has evaluated the consequences of the proposed action. Air concentrations and surface deposition levels were estimated using an atmospheric dispersion model. Degradation of fog oil and incorporation of graphite in the soil column will limit the residual impacts of the planned action. No significant impacts to air, water, and soil quality are anticipated. risks to the environment posed by the proposed action were determined to be minimal or below levels previously found to pose measurable impacts. Cultural resources are present on YPG and have been identified in adjacent areas; therefore, off-road activities should be preceded by a cultural resource survey. A Finding of No Significant Impact is recommended. 61 refs., 1 fig.

  3. Unit commitment with wind power generation: integrating wind forecast uncertainty and stochastic programming.

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, E. M.; Zavala, V. M.; Rocklin, M.; Lee, S.; Anitescu, M. (Mathematics and Computer Science); (Univ. of Chicago); (New York Univ.)

    2009-10-09

    We present a computational framework for integrating the state-of-the-art Weather Research and Forecasting (WRF) model in stochastic unit commitment/energy dispatch formulations that account for wind power uncertainty. We first enhance the WRF model with adjoint sensitivity analysis capabilities and a sampling technique implemented in a distributed-memory parallel computing architecture. We use these capabilities through an ensemble approach to model the uncertainty of the forecast errors. The wind power realizations are exploited through a closed-loop stochastic unit commitment/energy dispatch formulation. We discuss computational issues arising in the implementation of the framework. In addition, we validate the framework using real wind speed data obtained from a set of meteorological stations. We also build a simulated power system to demonstrate the developments.

  4. Bursts in intermittent aeolian saltation

    CERN Document Server

    Carneiro, M V; Herrmann, H J

    2014-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of intermittent flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the critical Shields number $\\theta_c$. The time delay between each burst decreases on average with the increase of the Shields number until saltation becomes non-intermittent and the sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain intermittent flux even below the threshold $\\theta_c$ for natural saltation initiation.

  5. The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts

    CERN Document Server

    Evans, P A; Osborne, J P; O'Brien, P T; Page, K L; Markwardt, C B; Barthelmy, S D; Beardmore, A P; Burrows, D N; Pagani, C; Starling, R L C; Romano, P

    2010-01-01

    Context: Gamma Ray Burst models predict the broadband spectral evolution and the temporal evolution of the energy flux. In contrast, standard data analysis tools and data repositories provide count-rate data, or use single flux conversion factors for all of the data, neglecting spectral evolution. Aims: To produce Swift BAT and XRT light curves in flux units, where the spectral evolution is accounted for. Methods: We have developed software to use the hardness ratio information to track spectral evolution of GRBs, and thus to convert the count-rate light curves from the BAT and XRT instruments on Swift into accurate, evolution-aware flux light curves. Results: The Swift Burst Analyser website (http://www.swift.ac.uk/burst_analyser) contains BAT, XRT and combined BAT-XRT flux light curves in three energy regimes for all GRBs observed by the Swift satellite. These light curves are automatically built and updated when data become available, are presented in graphical and plain-text format, and are available for ...

  6. Generations.

    Science.gov (United States)

    Chambers, David W

    2005-01-01

    Groups naturally promote their strengths and prefer values and rules that give them an identity and an advantage. This shows up as generational tensions across cohorts who share common experiences, including common elders. Dramatic cultural events in America since 1925 can help create an understanding of the differing value structures of the Silents, the Boomers, Gen Xers, and the Millennials. Differences in how these generations see motivation and values, fundamental reality, relations with others, and work are presented, as are some applications of these differences to the dental profession.

  7. Transfer of the Kenyan Kikuyu Male Circumcision Ritual to Future Generations Living in the United States

    Science.gov (United States)

    Mbito, Michael N.; Malia, Julia A.

    2009-01-01

    This phenomenological research report from analysis of interviews with 18 participants focuses on the theme of transferring an age-old initiation-into-manhood circumcision ritual to future generations of Kenyan Kikuyu who are living in the US. We identified three subthemes and found a strong indication that, while personally meaningful to the…

  8. Quantity, Quality, and Availability of Waste Heat from United States Thermal Power Generation.

    Science.gov (United States)

    Gingerich, Daniel B; Mauter, Meagan S

    2015-07-21

    Secondary application of unconverted heat produced during electric power generation has the potential to improve the life-cycle fuel efficiency of the electric power industry and the sectors it serves. This work quantifies the residual heat (also known as waste heat) generated by U.S. thermal power plants and assesses the intermittency and transport issues that must be considered when planning to utilize this heat. Combining Energy Information Administration plant-level data with literature-reported process efficiency data, we develop estimates of the unconverted heat flux from individual U.S. thermal power plants in 2012. Together these power plants discharged an estimated 18.9 billion GJ(th) of residual heat in 2012, 4% of which was discharged at temperatures greater than 90 °C. We also characterize the temperature, spatial distribution, and temporal availability of this residual heat at the plant level and model the implications for the technical and economic feasibility of its end use. Increased implementation of flue gas desulfurization technologies at coal-fired facilities and the higher quality heat generated in the exhaust of natural gas fuel cycles are expected to increase the availability of residual heat generated by 10.6% in 2040.

  9. An Instability-driven Dynamo for $\\gamma$ Ray Bursts

    CERN Document Server

    Araya-Gochez, R A

    2000-01-01

    We show that an MHD-instability driven dynamo (IDD) operating in a hot accretion disk is capable of generating energetically adequate magnetic flux deposition rates above and below a mildly advective accretion disk structure. The dynamo is driven by the magnetorotational instability (MRI) of a toroidal field in a shear flow and is limited by the buoyancy of `horizontal' flux and by reconnection in the turbulent medium. The efficiency of magnetic energy deposition is estimated to be comparable to the neutrino losses although an MHD collimation mechanism may deem this process a more viable alternative to neutrino-burst-driven models of gamma ray bursts.

  10. Gamma-ray bursts and terrestrial planetary atmospheres

    CERN Document Server

    Thomas, B C; Thomas, Brian C.; Melott, Adrian L.

    2006-01-01

    We describe results of modeling the effects of gamma-ray bursts (GRBs) within a few kiloparsecs of an Earth-like planet. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone depletion leads to an increase in solar UVB radiation at the surface, enhancing DNA damage, particularly in marine microorganisms such as phytoplankton. In addition, we expect increased atmospheric opacity due to buildup of nitrogen dioxide produced by the burst and enhanced precipitation of nitric acid. We review here previous work on this subject and discuss recent developments.

  11. Development and field tests of a damping controller to mitigate electromechanical oscillations on large diesel generating units

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Fabricio G.; Barreiros, Jose A.L.; Barra, Walter Jr.; Costa, Carlos T. Jr. [Universidade Federal do Para (UFPA), Instituto de Tecnologia, Faculdade de Engenharia Eletrica, Campus Universitario do Guama, CEP: 66075-900, Belem (Brazil); Ferreira, Andre M.D. [Instituto Federal de Educacao, Ciencia e Tecnologia do Para (IFPA), Campus Belem, Departamento de Controle e Processos Industriais, Av. Almirante Barroso, 1155 (Marco), CEP: 66093-020, Belem (Brazil)

    2011-02-15

    This paper presents the development and field tests of a digital damping controller designed to mitigate intra-plant electromechanical oscillations via the speed governor system of fast acting units. The controller performance is assessed on an 18-MVA diesel generating unit, at Santana Power Plant (Amapa State, Amazon Region at Northern Brazil). In order to design the damping control law, a set of parametric ARX models representing the plant dynamics at several load conditions, are previously identified from data collected on field tests. The damping controller gains are calculated by using the identified ARX models parameters as inputs to a discrete-time pole-placement design method (pole-shifting) and then embedded on a DSP based microcontroller digital system, for field tests assessment. The digital damping controller modulates the diesel engine inlet valve position according to the observed oscillation on the measured electric power, using a PWM device, which is specially developed to this application. The experimental results shown the good performance of the developed controller on damping efficiently the electromechanical oscillations observed between generating units at Santana Power Plant. (author)

  12. High Redshift Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil

    2012-01-01

    The Swift Observatory has been detecting 100 gamma-ray bursts per year for 7 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from 1 minute after the burst, continuing for days. GRBs are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=9.4 giving information on metallicity, star formation rate and reionization. The talk will present the latest results.

  13. A Multi-Objective Unit Commitment Model for Setting Carbon Tax to Reduce CO2 Emission: Thailand's Electricity Generation Case

    Directory of Open Access Journals (Sweden)

    Nuchjarin Intalar

    2015-07-01

    Full Text Available Carbon tax policy is a cost-effective instrument for emission reduction. However, setting the carbon tax is one of the challenging task for policy makers as it will lead to higher price of emission-intensive sources especially the utility price. In a large-scale power generation system, minimizing the operational cost and the environmental impact are conflicting objectives and it is difficult to find the compromise solution. This paper proposes a methodology of finding a feasible carbon tax rate on strategic level using the operational unit commitment model. We present a multi-objective mixed integer linear programming model to solve the unit commitment problem and consider the environmental impacts. The methodology of analyzing of the effect of carbon tax rates on the power generation, operating cost, and CO2 emission is also provided. The trade-off relationship between total operating cost and total CO2 emission is presented in the Pareto-optimal curve to analyze the feasible carbon tax rate that is influencing on electricity operating cost. The significant outcome of this paper is a modeling framework for the policy makers to determine the possible carbon tax that can be imposed on the electricity generation.

  14. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    Science.gov (United States)

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  15. Optimal placement of distributed generation units in distribution systems via an enhanced multi-objective particle swarm optimization algorithm

    Institute of Scientific and Technical Information of China (English)

    Shan CHENG; Min-you CHEN; Rong-jong WAI; Fang-zong WANG

    2014-01-01

    This paper deals with the optimal placement of distributed generation (DG) units in distribution systems via an enhanced multi-objective particle swarm optimization (EMOPSO) algorithm. To pursue a better simulation of the reality and provide the designer with diverse alternative options, a multi-objective optimization model with technical and operational con-straints is constructed to minimize the total power loss and the voltage fluctuation of the power system simultaneously. To enhance the convergence of MOPSO, special techniques including a dynamic inertia weight and acceleration coefficients have been inte-grated as well as a mutation operator. Besides, to promote the diversity of Pareto-optimal solutions, an improved non-dominated crowding distance sorting technique has been introduced and applied to the selection of particles for the next iteration. After verifying its effectiveness and competitiveness with a set of well-known benchmark functions, the EMOPSO algorithm is em-ployed to achieve the optimal placement of DG units in the IEEE 33-bus system. Simulation results indicate that the EMOPSO algorithm enables the identification of a set of Pareto-optimal solutions with good tradeoff between power loss and voltage sta-bility. Compared with other representative methods, the present results reveal the advantages of optimizing capacities and loca-tions of DG units simultaneously, and exemplify the validity of the EMOPSO algorithm applied for optimally placing DG units.

  16. The United States Particle Accelerator School: Educating the next generation of accelerator scientists and engineers

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, William A.; /MIT

    2008-09-01

    Only a handful of universities in the US offer any formal training in accelerator science. The United States Particle Accelerator School (USPAS) is National Graduate Educational Program that has developed a highly successful educational paradigm that, over the past twenty-years, has granted more university credit in accelerator / beam science and technology than any university in the world. Sessions are held twice annually, hosted by major US research universities that approve course credit, certify the USPAS faculty, and grant course credit. The USPAS paradigm is readily extensible to other rapidly developing, crossdisciplinary research areas such as high energy density physics.

  17. Ethical Audit Practice in Hospital Units – the Pillar of the Third Generation of Ethics

    Directory of Open Access Journals (Sweden)

    Daniela Tatiana AGHEORGHIESEI CORODEANU

    2016-12-01

    Full Text Available This article represents a manifest point of view with regard to the need to adopt the ethical audit in assessing the performance of the hospital unit in Romania, in the context of the accreditation and of the increasing pressure of the internal and external stakeholders for transparency, ethical and responsible behavior in assuming and fulfilling the mission. In support of the arguments, there is an overview of the opinions of several authors found in the profile specialty literature, but also of the research carried out at international and national level on this topic.

  18. Bursting Ca2+ Oscillations and Synchronization in Coupled Cells

    Institute of Scientific and Technical Information of China (English)

    JI Quan-Bao; LU Qi-Shao; Yang Zhuo-Qin; Duan Li-Xia

    2008-01-01

    A mathematical model proposed by Grubelnk et al. [Biophys. Chem. 94 (2001) 59] is employed to study the physiological role of mitochondria and the cytosolic proteins in generating complex Ca2+ oscillations. Intracellular bursting calcium oscillations of point-point, point cycle and two-folded limit cycle types are observed and explanations are given based on the fast/slow dynamical analysis, especially for point-cycle and two-folded limit cycle types, which have not been reported before. Furthermore, synchronization of coupled bursters of Ca2+oscillations via gap junctions and the effect of bursting types on synchronization of coupled cells are studied. It is argued that bursting oscillations of point-point type may be superior to achieve synchronization than that of point-cycle type.

  19. Thalamic neuron models encode stimulus information by burst-size modulation

    Directory of Open Access Journals (Sweden)

    Daniel Henry Elijah

    2015-09-01

    Full Text Available Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of

  20. Thalamic neuron models encode stimulus information by burst-size modulation.

    Science.gov (United States)

    Elijah, Daniel H; Samengo, Inés; Montemurro, Marcelo A

    2015-01-01

    Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here, we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of thalamic neurons.

  1. Fast and slow frequency-drifting millisecond bursts in Jovian decametric radio emissions

    Science.gov (United States)

    Ryabov, V. B.; Zarka, P.; Hess, S.; Konovalenko, A.; Litvinenko, G.; Zakharenko, V.; Shevchenko, V. A.; Cecconi, B.

    2014-08-01

    We present an analysis of several Jovian Io-related decametric radio storms recorded in 2004-2012 at the Ukrainian array UTR-2 using the new generation of baseband digital receivers. Continuous baseband sampling within sessions lasting for several hours enabled us to study the evolution of multiscale spectral patterns during the whole storm at varying time and frequency resolutions and trace the temporal transformation of burst structures in unprecedented detail. In addition to the well-known frequency drifting millisecond patterns known as S bursts we detected two other classes of events that often look like S bursts at low resolution but reveal a more complicated structure in high resolution dynamic spectra. The emissions of the first type (LS bursts, superposition of L and S type emissions) have a much lower frequency drift rate than the usual quasi linearly drifting S bursts (QS) and often occur within a frequency band where L emission is simultaneously present, suggesting that both LS and at least part of L emissions may come from the same source. The bursts of the second type (modulated S bursts called MS) are formed by a wideband frequency-modulated envelope that can mimic S bursts with very steep negative (or even positive) drift rates. Observed with insufficient time-frequency resolution, MS look like S bursts with complex shapes and varying drifts; MS patterns often occur in association with (i) narrowband emission; (ii) S burst trains; or (iii) sequences of fast drift shadow events. We propose a phenomenological description for various types of S emissions, that should include at least three components: high- and low-frequency limitation of the overall frequency band of the emission, fast frequency modulation of emission structures within this band, and emergence of elementary S burst substructures, that we call "forking" structures. All together, these three components can produce most of the observed spectral structures, including S bursts with

  2. Eccentric gravitational wave bursts in the post-Newtonian formalism

    Science.gov (United States)

    Loutrel, Nicholas; Yunes, Nicolás

    2017-07-01

    The detection of GW150914 by ground based gravitational wave observatories has brought about a new era in astrophysics. At optimal sensitivity, these observatories are expected to detect several events each year, with one or two of these occurring with non-negligible eccentricity. Such eccentric binaries will emit bursts of gravitational radiation during every pericenter passage, where orbital velocities can reach greater than ten percent the speed of light. As a result, such binaries may prove to be powerful probes of extreme gravitational physics and astrophysics. A promising method of achieving detection of such binaries is through power stacking, where the power in each burst is added up in time-frequency space. This detection strategy requires a theoretical prior of where the bursts will occur in time and frequency so that one knows where to search for successive bursts. We here present a generic post-Newtonian formalism for constructing such time-frequency model priors at generic post-Newtonian order. We apply our formalism to generate a burst model at third post-Newtonian order, making it potentially the most accurate, fully analytic model to date.

  3. Emergent synchronous bursting of oxytocin neuronal network.

    Directory of Open Access Journals (Sweden)

    Enrico Rossoni

    Full Text Available When young suckle, they are rewarded intermittently with a let-down of milk that results from reflex secretion of the hormone oxytocin; without oxytocin, newly born young will die unless they are fostered. Oxytocin is made by magnocellular hypothalamic neurons, and is secreted from their nerve endings in the pituitary in response to action potentials (spikes that are generated in the cell bodies and which are propagated down their axons to the nerve endings. Normally, oxytocin cells discharge asynchronously at 1-3 spikes/s, but during suckling, every 5 min or so, each discharges a brief, intense burst of spikes that release a pulse of oxytocin into the circulation. This reflex was the first, and is perhaps the best, example of a physiological role for peptide-mediated communication within the brain: it is coordinated by the release of oxytocin from the dendrites of oxytocin cells; it can be facilitated by injection of tiny amounts of oxytocin into the hypothalamus, and it can be blocked by injection of tiny amounts of oxytocin antagonist. Here we show how synchronized bursting can arise in a neuronal network model that incorporates basic observations of the physiology of oxytocin cells. In our model, bursting is an emergent behaviour of a complex system, involving both positive and negative feedbacks, between many sparsely connected cells. The oxytocin cells are regulated by independent afferent inputs, but they interact by local release of oxytocin and endocannabinoids. Oxytocin released from the dendrites of these cells has a positive-feedback effect, while endocannabinoids have an inhibitory effect by suppressing the afferent input to the cells.

  4. Near-Range Receiver Unit of Next Generation PollyXT Used with Koldeway Aerosol Raman Lidar in Arctic

    Directory of Open Access Journals (Sweden)

    Stachlewska Iwona S.

    2016-01-01

    Full Text Available The Near-range Aerosol Raman lidar (NARLa receiver unit, that was designed to enhance the detection range of the NeXT generation PollyXT Aerosol-Depolarization-Raman (ADR lidar of the University of Warsaw, was employed next the Koldeway Aerosol Raman Lidar (KARL at the AWI-IPEV German-French station in Arctic during Spring 2015. Here we introduce shortly design of both lidars, the scheme of their installation next to each other, and preliminary results of observations aiming at arctic haze investigation by the lidars and the iCAP a set of particle counter and aethalometer installed under a tethered balloon.

  5. The micro-generation installations in the United Kingdom; Les installations de microgeneration au Royaume-Uni

    Energy Technology Data Exchange (ETDEWEB)

    Thierry, X

    2007-02-15

    In the framework of the greenhouse effect gases emission fight, the United Kingdom decided to favor the development of the renewable energies and the energy efficiency. As the buildings represents 50% of the energy consumption, it was fundamental to implement programs aiming the energy control in buildings. In the possible solutions the use of microsystems of energy production is poorly represented. So the government is developing measures and research programs to promote an efficient use of the micro-generation. The document presents this program. (A.L.B.)

  6. A Comprehensive Design Approach of Power Electronic-Based Distributed Generation Units Focused on Power Quality Improvement

    DEFF Research Database (Denmark)

    Esparza, Miguel; Segundo-Ramirez, Juan; Nunez, Ciro

    2017-01-01

    The undesirable harmonic distortion produced by distributed generation units (DGUs) based on power electronic inverters presents operating and power quality challenges in electric systems. ‡e level of distortion depends on the internal elements of the DGUs as well as on the characteristics...... of the grid, loads, controls, among others. ‡is paper presents a comprehensive method, focused on power quality indexes and e�ciency for the design of micro-grids with multiple DGUs interconnected to the AC grid through three phase multi-Megawatt medium-voltage PWM voltage source inverters (PWM-VSI). ‡e...

  7. Structure formation of aerated concrete containing waste coal combustion products generated in the thermal vortex power units

    Science.gov (United States)

    Ivanov, A. I.; Stolboushkin, A. Yu; Temlyanstev, M. V.; Syromyasov, V. A.; Fomina, O. A.

    2016-10-01

    The results of fly ash research, generated in the process of waste coal combustion in the thermal vortex power units and used as an aggregate in aerated concrete, are provided. It is established that fly ash can be used in the production of cement or concrete with low loss on ignition (LOI). The permitted value of LOI in fly ash, affecting the structure formation and operational properties of aerated concrete, are defined. During non-autoclaved hardening of aerated concrete with fly ash aggregate and LOI not higher than 2%, the formation of acicular crystals of ettringite, reinforcing interporous partitions, takes place.

  8. Detection of artifacts from high energy bursts in neonatal EEG.

    Science.gov (United States)

    Bhattacharyya, Sourya; Biswas, Arunava; Mukherjee, Jayanta; Majumdar, Arun Kumar; Majumdar, Bandana; Mukherjee, Suchandra; Singh, Arun Kumar

    2013-11-01

    Detection of non-cerebral activities or artifacts, intermixed within the background EEG, is essential to discard them from subsequent pattern analysis. The problem is much harder in neonatal EEG, where the background EEG contains spikes, waves, and rapid fluctuations in amplitude and frequency. Existing artifact detection methods are mostly limited to detect only a subset of artifacts such as ocular, muscle or power line artifacts. Few methods integrate different modules, each for detection of one specific category of artifact. Furthermore, most of the reference approaches are implemented and tested on adult EEG recordings. Direct application of those methods on neonatal EEG causes performance deterioration, due to greater pattern variation and inherent complexity. A method for detection of a wide range of artifact categories in neonatal EEG is thus required. At the same time, the method should be specific enough to preserve the background EEG information. The current study describes a feature based classification approach to detect both repetitive (generated from ECG, EMG, pulse, respiration, etc.) and transient (generated from eye blinking, eye movement, patient movement, etc.) artifacts. It focuses on artifact detection within high energy burst patterns, instead of detecting artifacts within the complete background EEG with wide pattern variation. The objective is to find true burst patterns, which can later be used to identify the Burst-Suppression (BS) pattern, which is commonly observed during newborn seizure. Such selective artifact detection is proven to be more sensitive to artifacts and specific to bursts, compared to the existing artifact detection approaches applied on the complete background EEG. Several time domain, frequency domain, statistical features, and features generated by wavelet decomposition are analyzed to model the proposed bi-classification between burst and artifact segments. A feature selection method is also applied to select the

  9. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  10. Symmetry of oculomotor burst neuron coordinates about Listing's plane.

    Science.gov (United States)

    Crawford, J D; Vilis, T

    1992-08-01

    1. The purpose of this investigation was to determine the axes of eye rotation generated by oculomotor burst neuron populations and the coordinate system that they collectively define. In particular, we asked if such coordinates might be related to constraints in the emergent behavior, i.e., Listing's law for saccades. 2. The mesencephalic rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) was identified in four monkeys with the use of single-unit recording, and then explored with the use of electrical microstimulation and pharmacological inactivation with the inhibitory gamma-aminobutyric acid (GABA) agonist muscimol. Three-dimensional (3-D) eye positions and velocities were recorded in one or both eyes while alert animals made eye movements in response to visual stimuli and head rotation. 3. Unilateral stimulation of the riMLF (20 microA, 200 Hz, 300-600 ms) produced conjugate, constant velocity eye rotations, which then stopped abruptly and held their final positions. This is expected if the riMLF produces phasic signals upstream from the oculomotor integrator. 4. Units that burst before upward or downward saccades were recorded intermingled in each side of the riMLF. Unilateral stimulation of the same riMLF sites produced eye rotations about primarily torsional axes, clockwise (CW) during right riMLF stimulation and counterclockwise (CCW) during left stimulation. Only small and inconsistent vertical components were observed, supporting the view that the riMLF carries intermingled up and down signals. 5. The torsional axes of eye rotation produced by riMLF stimulation did not correlate to external anatomic landmarks. Instead, stimulation axes from both riMLF sides aligned with the primary gaze direction orthogonal to Listing's plane of eye positions recorded during saccades. 6. Injection of muscimol into one side of the riMLF produced a conjugate deficit in saccades and quick phases, including a 50% reduction in all vertical velocities

  11. FERMIGBRST - Fermi GBM Burst Catalog

    Data.gov (United States)

    National Aeronautics and Space Administration — This table lists all of the triggers observed by a subset of the 14 GBM detectors (12 NaI and 2 BGO) which have been classified as gamma-ray bursts (GRBs). Note that...

  12. Neutrino clustering and the Z-burst model

    OpenAIRE

    McKellar, B. H. J.; Garbutt, M.; Stephenson Jr., G. J.; T. Goldman

    2001-01-01

    The possibility that the observed Ultra High Energy Cosmic Rays are generated by high energy neutrinos creating "Z-bursts" in resonant interactions with the background neutrinos has been proposed, but there are difficulties in generating enough events with reasonable incident neutrino fluxes. We point out that this difficulty is overcome if the background neutrinos have coalesced into "neutrino clouds" --- a possibility previously suggested by some of us in another context. The limitations th...

  13. Next Generation Attenuation Relationships for the Eastern United States (NGA-East)

    Energy Technology Data Exchange (ETDEWEB)

    Mahin, Stephen [Univ. of California, Berkeley, CA (United States); Bozorgnia, Yousef [Univ. of California, Berkeley, CA (United States)

    2016-04-11

    This is a progress report to DOE for project Next Generation Attenuation for Central & Eastern US (NGA-East).This progress report consists of numerous monthly progress segments starting June 1, 2010 until December 31, 2015. Please note: the December 2015 progress report was issued in January 2016 due to the final university financial reporting at the end of this project. For each month, there is a technical progress list, and an update on the financial progress of the project. As you know, this project is jointly funded by the DOE, US Nuclear Regulatory Commission (NRC) and Electric Power Research Institute (EPRI). Thus, each segment includes financial progress for these three funding agencies.

  14. Microscopic characteristics of burst coal seams

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.; Wang, C. [Shandong University of Science and Technology (China)

    2000-08-01

    Based on the analytical results of coal samples with microscope and scanning electron microscope, the paper explains the petrographic characteristics and microscopic depredation of burst coal. Quantitative analysis on the components and microstructures of the burst coal is conducted. The influence of the microscopic characteristics on coal burst is discussed. For coal seams with burst tendency, it has provided the necessary forecasting parameters. 2 refs., 1 fig., 2 tabs.

  15. Millisecond extragalactic radio bursts as magnetar flares

    CERN Document Server

    Popov, S B

    2013-01-01

    Properties of the population of millisecond extragalactic radio bursts discovered by Thornton et al. (2013) are in good correspondence with the hypothesis that such events are related to hyperflares of magnetars, as was proposed by us after the first observation of an extragalactic millisecond radio burst by Lorimer et al. (2007). We also point that some of multiple millisecond radio bursts from M31 discovered by Rubio-Herrera et al. (2013) also can be related to weaker magnetar bursts.

  16. Modularized architecture of address generation units suitable for real-time processing MR data on an FPGA.

    Science.gov (United States)

    Li, Limin; Wyrwicz, Alice M

    2016-06-01

    In this paper, we describe a modular approach to the design of an Address Generation Unit (AGU). The approach consists of development of a generic Address Generation Core (AGC) as a basic building block and the construction of an AGU from the AGCs. We illustrate this concept with AGUs capable of handling 2D- and 3D-structured data, and as well as their setup for executing 2D and 3D FFT algorithms on a Field Programmable Gate Array (FPGA). The AGUs developed using our proposed method are simple and easily expandable. Furthermore, they can potentially support irregularly structured data which are often generated from the wide variety of pulse sequences in magnetic resonance imaging. Our experimental results show that these AGUs are capable of generating addresses with a user-predefined pattern automatically at the speed of one address per clock cycle and operate at clock rates up to 80 MHz. They can operate concurrently with other processes and thus do not introduce additional operation latencies. Although we focus on applying the developed AGUs to executing 2D and 3D FFT, we expect that the modular design method should have much wider applications.

  17. Modularized architecture of address generation units suitable for real-time processing MR data on an FPGA

    Science.gov (United States)

    Li, Limin; Wyrwicz, Alice M.

    2016-06-01

    In this paper, we describe a modular approach to the design of an Address Generation Unit (AGU). The approach consists of development of a generic Address Generation Core (AGC) as a basic building block and the construction of an AGU from the AGCs. We illustrate this concept with AGUs capable of handling 2D- and 3D-structured data, and as well as their setup for executing 2D and 3D FFT algorithms on a Field Programmable Gate Array (FPGA). The AGUs developed using our proposed method are simple and easily expandable. Furthermore, they can potentially support irregularly structured data which are often generated from the wide variety of pulse sequences in magnetic resonance imaging. Our experimental results show that these AGUs are capable of generating addresses with a user-predefined pattern automatically at the speed of one address per clock cycle and operate at clock rates up to 80 MHz. They can operate concurrently with other processes and thus do not introduce additional operation latencies. Although we focus on applying the developed AGUs to executing 2D and 3D FFT, we expect that the modular design method should have much wider applications.

  18. Summary of three regional assessment studies of solar electric generation opportunities in the Southwest, Southeast, and Northeast United States

    Energy Technology Data Exchange (ETDEWEB)

    Watts, R.L.; Harty, H.

    1981-02-01

    Market opportunities for solar generation of electricity for utility and for residential/commercial/industrial applications in the Northeast, Southeast, and Southwest regions of the United States were evaluated in three studies (JBF 1979, Stone and Webster 1979a, 1979b) and are summarized. The evaluations were based on both economic analyses and user perception of what they would require to select or approve the use of solar electric generation for themselves or for their employers. Over 30 utilities and several industrial and commercial firms and homeowners were involved. Solar electric technologies considered included biomass, hybrid retrofit, OTEC, photovoltaic, solar thermal, and wind. The studies projected that solar electric technologies could account for several percent of the forecast generation in year 2000 in the Southeast and Southwest regions,and up to 10 to 20% in the Northeast region. No single solar electric technology or application (for utility or industrial/commercial/residential use) arrived earlier at economic breakeven than other technologies in the Southeast region, but wind generation for both utility and industrial applications predominated in the Northeast region. The Southwest region, in which only utility applications were considered, showed wind energy and retrofit hybrid (a solar adjunct to an existing fossil-fueled plant) to be the most likely early applications.

  19. Unit Sizing and Cost Analysis of Renewable Energy based Hybrid Power Generation System - A Case Study

    Directory of Open Access Journals (Sweden)

    Nitin AGARWAL

    2014-01-01

    Full Text Available A simulation model is developed for optimal sizing and analysis of a PV-diesel-battery based hybrid power generation system with the objectives to minimize life cycle cost and CO2 emission, while maintaining the desired system autonomy. A case study of a boy’s hostel in Moradabad district is taken for analysis purposes. It has 91 rooms with a capacity of 3 boys in each room. The decision variables included in the optimization methodology are total PV area, number of PV modules of 600 Wp, diesel generator power, fuel consumption per year and number of 24 V and 150 Ah batteries. The simulation result shows that the PV percentage of 86 % and diesel penetration of 14 % gives the most optimized solution with minimum LCC of $110,547 and average CO2 emission of 28 kg/day. The developed model has been validated by comparing its results with earlier research work.doi:10.14456/WJST.2014.24

  20. L-calcium channel involving the generation and maintenance of bursting firing in rat substantia nigra pars compacta dopaminergic neurons%L-钙离子通道参与大鼠黑质致密部多巴胺能神经元暴发式放电模式产生和维持的机制

    Institute of Scientific and Technical Information of China (English)

    薛伟宁; 王元; 李志方; 孙彬彬; 刘力学; 张乐石; 樊双义

    2015-01-01

    Objective To evaluate the role of calcium channel in the mechanism of the generation and maintenance of bursting firing of substantia nigra pars compacta (SNc) dopaminergic neurons in rats.Methods Using the patch clamp technique,we observed the firing pattern switching features after adding 10 μmol/L N-methyl-D-aspartic acid (NMDA),compared the changes of whole-calcium current and L-type calcium current with or without NMDA,and analyzed the correlation between the generation of burst firing and L-type calcium channel activation.Results After NMDA treatment,the firing pattern of SNc dopaminergic neurons changed to burst firing,which was compromised by a charastistic high plateau potential and series of action potential on it.The current density of L-type calcium current increased significantly after adding NMDA,which,from (2.86 ±0.26) pA/pF (n =28),significantly increased to (3.75 ± 0.18) pA/pF (n =34 ; t =7.52,P =0.002 8).The high plateau potential was almost abolished with the application of verapamil,a specific antagonist of L-type calcium channel.Consiusion NMDA could induce the firing pattern changed to burst firing in SNc dopaminergic neurons,while L-type calcium channel contributes to the process of generation and maintenance of burst firing.%目的 研究钙离子通道对大鼠黑质致密部(SNc)多巴胺能神经元暴发式放电模式产生和维持的机制.方法 应用全细胞膜片钳的方法,施加N-甲基-D-天冬氨酸(NMDA)诱导神经元放电模式转变,观察并记录其相应放电模式的特点,记录并比较加入10 μmol/L NMDA前后全钙离子流和L-钙电流的变化情况,通过外液加入河豚毒素、维拉帕米、氯化镍后,分析暴发式放电产生和维持与L-钙通道激活之间的联系.结果 加入NMDA后神经元放电模式转变为暴发式放电,该暴发式放电为平台电位及其上的动作电位构成;L-钙通道电流密度峰值在加入NMDA后明显增加,从(2.86±0.26) pA/pF(n =28)增加到(3

  1. Gamma-ray bursts and collisionless shocks

    CERN Document Server

    Waxman, E

    2006-01-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from few GeV to >10^{20} eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of gamma-ray burst (GRB) "afterglows" provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars, and their "afterglows," delayed low energy emission following the prompt burst of gamma-rays, are produced by relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Some of the striking characteristics of these shocks include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ...

  2. Optimization of Cooling Unit Design for Automotive Exhaust-Based Thermoelectric Generators

    Science.gov (United States)

    Su, C. Q.; Xu, M.; Wang, W. S.; Deng, Y. D.; Liu, X.; Tang, Z. B.

    2015-06-01

    Integrating a thermoelectric cooler (TEC) into the engine cooling system has various advantages including reducing additional mechanical parts, and saving energy and space for automotive applications. Based on performance parameters of the engine and thermoelectric modules, three different TEC configurations called plate-shape, stripe-shape, and diamond-shape are constructed with development of simulations of the different TECs and the performance of the circulating coolant. Based on these simulations, the velocity, pressure, and temperature fields of the coolant are obtained for further research. Besides, the temperature of the TEC and the output power of the thermoelectric generator (TEG) are acquired experimentally. Comparing the working performance of the different TECs, the simulation and experimental results show that the TEG using the diamond-shaped TEC achieves a relatively ideal performance. Finally, some measures are proposed to improve the cooling system, providing guidelines for future research.

  3. Dynamic Placement of Wind Power Distributed Generation Units in Distribution Power Systems

    DEFF Research Database (Denmark)

    Hajizadeh, Amin; Baghayipour, Mohammad Reza

    2017-01-01

    process. Thereby, an accurate dynamic model of the active and reactive powers injected by Wind DG to the system is employed in which the interactions between the Wind DG and the distribution network are well regarded. Finally, simulation results are given to show the capability of proposed approach......The placement problem of Distributed Generators (DGs) in distribution networks becomes much more complicated in the case of using the DGs with renewable energy resources, due to several causes like their intermittent output powers, the interactions between DGs and the rest of distribution network......, and other involved uncertainties. This paper develops a new approach for optimal placement of Wind DGs in which all of such influences are perfectly handled. This method simultaneously considers the time variations of dynamic nodal demands, nodal voltage magnitudes, and wind speed in the Wind DG placement...

  4. Research on a Power Management System for Thermoelectric Generators to Drive Wireless Sensors on a Spindle Unit

    Directory of Open Access Journals (Sweden)

    Sheng Li

    2014-07-01

    Full Text Available Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

  5. Research on a power management system for thermoelectric generators to drive wireless sensors on a spindle unit.

    Science.gov (United States)

    Li, Sheng; Yao, Xinhua; Fu, Jianzhong

    2014-07-16

    Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

  6. Clinical fit of all-ceramic three-unit fixed partial dentures, generated with three different CAD/CAM systems.

    Science.gov (United States)

    Reich, Sven; Wichmann, Manfred; Nkenke, Emeka; Proeschel, Peter

    2005-04-01

    In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal-ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 microm for DIGI, 65 microm for LAVA and INLA and 54 microm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use.

  7. Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions.

    Science.gov (United States)

    Tetzlaff, D; Birkel, C; Dick, J; Geris, J; Soulsby, C

    2014-02-01

    We examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment. The units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone. The peaty gleys and peats remained saturated throughout the year, while the podzols showed distinct wetting and drying cycles. In this region, most precipitation events are 80% of flow, even in large events, reflecting the displacement of water from the riparian soils that has been stored in the catchment for >2 years. These riparian areas are the key zone where different source waters mix. Our study is novel in showing that they act as "isostats," not only regulating the isotopic composition of stream water, but also integrating the transit time distribution for the catchment. Hillslope connectivity is controlled by small storage changes in soil unitsDifferent catchment source waters mix in large riparian wetland storageIsotopes show riparian wetlands set the catchment transit time distribution.

  8. The development of close relationships in Japan and the United States: paths of symbiotic harmony and generative tension.

    Science.gov (United States)

    Rothbaum, F; Pott, M; Azuma, H; Miyake, K; Weisz, J

    2000-01-01

    Findings from research on parent-child and adult mate relationships suggest that there are different paths of development in Japan and the United States. In Japan, the path is one of symbiotic harmony, as seen in the emphasis on union in infancy, others' expectations in childhood, the stability of relationships with parents and peers in adolescence, and assurance about the mate relationship in adulthood. In the United States, the path is one of generative tension, as seen in the tug between separation and reunion in infancy, the emphasis on personal preferences in childhood, the transfer of closeness from parents to peers in adolescence, and the emphasis on trust-a faith and hope in new relationships-in adulthood. The notion that there are different paths of development challenges Western investigators' presumption that certain processes-separation-individuation, use of the relational partner as a secure base for exploration, and conflict between partners-are central in all relationships. The notion of different paths also challenges the assumption of many cross-cultural investigators that relationships in the United States are less valued or weaker than those in Japan; this article highlights cultural differences in the meaning and dynamics, as opposed to the importance and strength, of relationships. The model suggests a need to investigate the processes underlying, and the adaptive consequences of, these two alternative paths.

  9. Teaching Generative Reading Via Recombination of Minimal Textual Units: A Legacy of Verbal Behavior to Children in Brazil

    Science.gov (United States)

    de Souza, Deisy G.; de Rose, Julio C.; Faleiros, Thais C.; Bortoloti, Renato; Hanna, Elenice Seixas; McIlvane, William J.

    2009-01-01

    This paper reports results of two studies that sought to teach generative reading skills to a large group of Brazilian children who were exhibiting protracted failure in school. Inspired by Skinner’s analysis of verbal relations and minimal verbal units, the methodology took advantage of certain characteristics of Portuguese. Many words in this language are comprised of two-letter syllabic units (e.g., BO+LA= ball, CA+BO= handle, LA+TA= can) that can be recombined to form new words (e.g., BOCA= mouth, BOTA= boot), thus establishing a route to generative reading via recombinative generalization. Such syllabic units were incorporated within curricular framework that used matching-to-sample and learning by exclusion methods to teach matching relations involving pictures, printed and spoken words, and printed and spoken syllables. Study 1 was conducted within a university-based learning center that maintained certain aspects of laboratory conditions. It showed that teaching textual relations between dictated and printed syllables could control procedurally the inter- and intra-participant variability observed in past studies that lacked this feature -resulting in virtually universally positive teaching outcomes. Study 2 was conducted in a public school programs that applied the same basic training methodology. Positive training outcomes in an experimental group were approximately 3–5 times greater than that in a placebo control group. Together, these studies illustrate that the functional analysis in Verbal Behavior is having a direct impact in educational science in Brazil. It has led to procedures that can be effectively translated from the laboratory to the community via delivery systems that can be implemented in the developing world. PMID:19960112

  10. Updated greenhouse gas and criteria air pollutant emission factors and their probability distribution functions for electricity generating units

    Energy Technology Data Exchange (ETDEWEB)

    Cai, H.; Wang, M.; Elgowainy, A.; Han, J. (Energy Systems)

    2012-07-06

    Greenhouse gas (CO{sub 2}, CH{sub 4} and N{sub 2}O, hereinafter GHG) and criteria air pollutant (CO, NO{sub x}, VOC, PM{sub 10}, PM{sub 2.5} and SO{sub x}, hereinafter CAP) emission factors for various types of power plants burning various fuels with different technologies are important upstream parameters for estimating life-cycle emissions associated with alternative vehicle/fuel systems in the transportation sector, especially electric vehicles. The emission factors are typically expressed in grams of GHG or CAP per kWh of electricity generated by a specific power generation technology. This document describes our approach for updating and expanding GHG and CAP emission factors in the GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model developed at Argonne National Laboratory (see Wang 1999 and the GREET website at http://greet.es.anl.gov/main) for various power generation technologies. These GHG and CAP emissions are used to estimate the impact of electricity use by stationary and transportation applications on their fuel-cycle emissions. The electricity generation mixes and the fuel shares attributable to various combustion technologies at the national, regional and state levels are also updated in this document. The energy conversion efficiencies of electric generating units (EGUs) by fuel type and combustion technology are calculated on the basis of the lower heating values of each fuel, to be consistent with the basis used in GREET for transportation fuels. On the basis of the updated GHG and CAP emission factors and energy efficiencies of EGUs, the probability distribution functions (PDFs), which are functions that describe the relative likelihood for the emission factors and energy efficiencies as random variables to take on a given value by the integral of their own probability distributions, are updated using best-fit statistical curves to characterize the uncertainties associated with GHG and CAP emissions in life

  11. Updated greenhouse gas and criteria air pollutant emission factors and their probability distribution functions for electricity generating units

    Energy Technology Data Exchange (ETDEWEB)

    Cai, H.; Wang, M.; Elgowainy, A.; Han, J. (Energy Systems)

    2012-07-06

    Greenhouse gas (CO{sub 2}, CH{sub 4} and N{sub 2}O, hereinafter GHG) and criteria air pollutant (CO, NO{sub x}, VOC, PM{sub 10}, PM{sub 2.5} and SO{sub x}, hereinafter CAP) emission factors for various types of power plants burning various fuels with different technologies are important upstream parameters for estimating life-cycle emissions associated with alternative vehicle/fuel systems in the transportation sector, especially electric vehicles. The emission factors are typically expressed in grams of GHG or CAP per kWh of electricity generated by a specific power generation technology. This document describes our approach for updating and expanding GHG and CAP emission factors in the GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model developed at Argonne National Laboratory (see Wang 1999 and the GREET website at http://greet.es.anl.gov/main) for various power generation technologies. These GHG and CAP emissions are used to estimate the impact of electricity use by stationary and transportation applications on their fuel-cycle emissions. The electricity generation mixes and the fuel shares attributable to various combustion technologies at the national, regional and state levels are also updated in this document. The energy conversion efficiencies of electric generating units (EGUs) by fuel type and combustion technology are calculated on the basis of the lower heating values of each fuel, to be consistent with the basis used in GREET for transportation fuels. On the basis of the updated GHG and CAP emission factors and energy efficiencies of EGUs, the probability distribution functions (PDFs), which are functions that describe the relative likelihood for the emission factors and energy efficiencies as random variables to take on a given value by the integral of their own probability distributions, are updated using best-fit statistical curves to characterize the uncertainties associated with GHG and CAP emissions in life

  12. Posttranslationally caused bioluminescence burst of the Escherichia coli luciferase reporter strain.

    Science.gov (United States)

    Ideguchi, Yamato; Oshikoshi, Yuta; Ryo, Masashi; Motoki, Shogo; Kuwano, Takashi; Tezuka, Takafumi; Aoki, Setsuyuki

    2016-01-01

    We continuously monitored bioluminescence from a wild-type reporter strain of Escherichia coli (lacp::luc+/WT), which carries the promoter of the lac operon (lacp) fused with the firefly luciferase gene (luc+). This strain showed a bioluminescence burst when shifted into the stationary growth phase. Bioluminescence profiles of other wild-type reporter strains (rpsPp::luc+ and argAp::luc+) and gene-deletion reporter strains (lacp::luc+/crp- and lacp::luc+/lacI-) indicate that transcriptional regulation is not responsible for generation of the burst. Consistently, changes in the luciferase protein levels did not recapitulate the profile of the burst. On the other hand, dissolved oxygen levels increased over the period across the burst, suggesting that the burst is, at least partially, caused by an increase in intracellular oxygen levels. We discuss limits of the firefly luciferase when used as a reporter for gene expression and its potential utility for monitoring metabolic changes in cells.

  13. Gamma-ray bursts as the death throes of massive binary stars

    CERN Document Server

    Narayan, R; Piran, T

    1992-01-01

    It is proposed that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Bursts with complex profiles and relatively long durations are the result of magnetic flares generated by the Parker instability in a post-merger differentially-rotating disk. Some bursts may also be produced through neutrino-antineutrino annihilation into electrons and positrons. In both cases, an optically thick fireball of size $\\sles\\ 100$ km is initially created, which expands ultrarelativistically to large radii before radiating. Several previous objections to the cosmological merger model are eliminated. It is predicted that $\\gamma$-ray bursts will be accompanied by a burst of gravitational radiation from the spiraling-in binary which could be detected by LIGO.

  14. BudBurst Buddies: Introducing Young Citizen Scientists to Plants and Environmental Change

    Science.gov (United States)

    Ward, D.; Gardiner, L. S.; Henderson, S.

    2011-12-01

    As part of Project BudBurst, the BudBurst Buddies recently moved to the National Ecological Network (NEON) as part of its Education and Public Engagement efforts. The BudBurst Buddies (www.budburstbuddies.org) were created to engage elementary school age children in the science of observing plants and the timing of phenological (life cycle) events. BudBurst Buddies is a part of the Project BudBurst national citizen science initiative (www.budburst.org), which allows individuals to engage in the scientific process, contributing to a better understanding of climate change while increasing public awareness of phenology and the impacts of climate change on plants. As a first step towards engaging the next generation of citizen scientists, BudBurst Buddies provides the opportunity for children to gain experience with scientific research and increases awareness of how plants change throughout the year. Hundreds of young students have participated in the inaugural year of BudBurst Buddies. Children can participate in BudBurst Buddies on their own, with their families, or in formal or informal education settings. The program was recently highlighted by education staff at the New York Hall of Science and numerous classrooms have been implementing this resource as part of their curriculum. Each child who participates creates a journal about a plant of his or her choosing, makes observations of the plant over the growing season and submits findings online, earning an official BudBurst Buddies certificate. An online storybook for kids tells how two children, Lily and Sage, observed plants in their neighborhood and became BudBurst Buddies. This presentation will provide an overview of the BudBurst Buddies resources including a new implementation guide and will also share feedback from the first year of implementation.

  15. Phase-locking of bursting neuronal firing to dominant LFP frequency components.

    Science.gov (United States)

    Constantinou, Maria; Elijah, Daniel H; Squirrell, Daniel; Gigg, John; Montemurro, Marcelo A

    2015-10-01

    Neuronal firing in the hippocampal formation relative to the phase of local field potentials (LFP) has a key role in memory processing and spatial navigation. Firing can be in either tonic or burst mode. Although bursting neurons are common in the hippocampal formation, the characteristics of their locking to LFP phase are not completely understood. We investigated phase-locking properties of bursting neurons using simulations generated by a dual compartmental model of a pyramidal neuron adapted to match the bursting activity in the subiculum of a rat. The model was driven with stochastic input signals containing a power spectral profile consistent with physiologically relevant frequencies observed in LFP. The single spikes and spike bursts fired by the model were locked to a preferred phase of the predominant frequency band where there was a peak in the power of the driving signal. Moreover, the preferred phase of locking shifted with increasing burst size, providing evidence that LFP phase can be encoded by burst size. We also provide initial support for the model results by analysing example data of spontaneous LFP and spiking activity recorded from the subiculum of a single urethane-anaesthetised rat. Subicular neurons fired single spikes, two-spike bursts and larger bursts that locked to a preferred phase of either dominant slow oscillations or theta rhythms within the LFP, according to the model prediction. Both power-modulated phase-locking and gradual shift in the preferred phase of locking as a function of burst size suggest that neurons can use bursts to encode timing information contained in LFP phase into a spike-count code.

  16. Expected ozone benefits of reducing nitrogen oxide (NOx) emissions from coal-fired electricity generating units in the eastern United States.

    Science.gov (United States)

    Vinciguerra, Timothy; Bull, Emily; Canty, Timothy; He, Hao; Zalewsky, Eric; Woodman, Michael; Aburn, George; Ehrman, Sheryl; Dickerson, Russell R

    2017-03-01

    On hot summer days in the eastern United States, electricity demand rises, mainly because of increased use of air conditioning. Power plants must provide this additional energy, emitting additional pollutants when meteorological conditions are primed for poor air quality. To evaluate the impact of summertime NOx emissions from coal-fired electricity generating units (EGUs) on surface ozone formation, we performed a series of sensitivity modeling forecast scenarios utilizing EPA 2018 version 6.0 emissions (2011 base year) and CMAQ v5.0.2. Coal-fired EGU NOx emissions were adjusted to match the lowest NOx rates observed during the ozone seasons (April 1-October 31) of 2005-2012 (Scenario A), where ozone decreased by 3-4 ppb in affected areas. When compared to the highest emissions rates during the same time period (Scenario B), ozone increased ∼4-7 ppb. NOx emission rates adjusted to match the observed rates from 2011 (Scenario C) increased ozone by ∼4-5 ppb. Finally in Scenario D, the impact of additional NOx reductions was determined by assuming installation of selective catalytic reduction (SCR) controls on all units lacking postcombustion controls; this decreased ozone by an additional 2-4 ppb relative to Scenario A. Following the announcement of a stricter 8-hour ozone standard, this analysis outlines a strategy that would help bring coastal areas in the mid-Atlantic region closer to attainment, and would also provide profound benefits for upwind states where most of the regional EGU NOx originates, even if additional capital investments are not made (Scenario A). With the 8-hr maximum ozone National Ambient Air Quality Standard (NAAQS) decreasing from 75 to 70 ppb, modeling results indicate that use of postcombustion controls on coal-fired power plants in 2018 could help keep regions in attainment. By operating already existing nitrogen oxide (NOx) removal devices to their full potential, ozone could be significantly curtailed, achieving ozone reductions by

  17. Multiple conductances cooperatively regulate spontaneous bursting in mouse olfactory bulb external tufted cells.

    Science.gov (United States)

    Liu, Shaolin; Shipley, Michael T

    2008-02-13

    External tufted (ET) cells are juxtaglomerular neurons that spontaneously generate bursts of action potentials, which persist when fast synaptic transmission is blocked. The intrinsic mechanism of this autonomous bursting is unknown. We identified a set of voltage-dependent conductances that cooperatively regulate spontaneous bursting: hyperpolarization-activated inward current (I(h)), persistent Na+ current (I(NaP)), low-voltage-activated calcium current (I(L/T)) mediated by T- and/or L-type Ca2+ channels, and large-conductance Ca2+-dependent K+ current (I(BK)). I(h) is important in setting membrane potential and depolarizes the cell toward the threshold of I(NaP) and I(T/L), which are essential to generate the depolarizing envelope that is crowned by a burst of action potentials. Action potentials depolarize the membrane and induce Ca2+ influx via high-voltage-activated Ca2+ channels (I(HVA)). The combined depolarization and increased intracellular Ca2+ activates I(BK), which terminates the burst by hyperpolarizing the membrane. Hyperpolarization activates I(h) and the cycle is regenerated. A novel finding is the role of L-type Ca2+ channels in autonomous ET cells bursting. A second novel feature is the role of BK channels, which regulate burst duration. I(L) and I(BK) may go hand-in-hand, the slow inactivation of I(L) requiring I(BK)-dependent hyperpolarization to deactivate inward conductances and terminate the burst. ET cells receive monosynaptic olfactory nerve input and drive the major inhibitory interneurons of the glomerular circuit. Modulation of the conductances identified here can regulate burst frequency, duration, and spikes per burst in ET cells and thus significantly shape the impact of glomerular circuits on mitral and tufted cells, the output channels of the olfactory bulb.

  18. Black Holes, Supernovae and Gamma Ray Bursts

    CERN Document Server

    Ruffini, Remo

    2013-01-01

    We review recent progress in our understanding of the nature of gamma ray bursts (GRBs) and in particular, of the relationship between short GRBs and long GRBs. The first example of a short GRB is described. The coincidental occurrence of a GRB with a supernova (SN) is explained within the induced gravitational collapse (IGC) paradigm, following the sequence: 1) an initial binary system consists of a compact carbon-oxygen (CO) core star and a neutron star (NS); 2) the CO core explodes as a SN, and part of the SN ejecta accretes onto the NS which reaches its critical mass and collapses to a black hole (BH) giving rise to a GRB; 3) a new NS is generated by the SN as a remnant. The observational consequences of this scenario are outlined.

  19. On hydrologic similarity: A dimensionless flood frequency model using a generalized geomorphologic unit hydrograph and partial area runoff generation

    Science.gov (United States)

    Sivapalan, Murugesu; Wood, Eric F.; Beven, Keith J.

    1993-01-01

    One of the shortcomings of the original theory of the geomorphologic unit hydrograph (GUH) is that it assumes that runoff is generated uniformly from the entire catchment area. It is now recognized that in many catchments much of the runoff during storm events is produced on partial areas which usually form on narrow bands along the stream network. A storm response model that includes runoff generation on partial areas by both Hortonian and Dunne mechanisms was recently developed by the authors. In this paper a methodology for integrating this partial area runoff generation model with the GUH-based runoff routing model is presented; this leads to a generalized GUH. The generalized GUH and the storm response model are then used to estimate physically based flood frequency distributions. In most previous work the initial moisture state of the catchment had been assumed to be constant for all the storms. In this paper we relax this assumption and allow the initial moisture conditions to vary between storms. The resulting flood frequency distributions are cast in a scaled dimensionless framework where issues such as catchment scale and similarity can be conveniently addressed. A number of experiments are performed to study the sensitivity of the flood frequency response to some of the 'similarity' parameters identified in this formulation. The results indicate that one of the most important components of the derived flood frequency model relates to the specification of processes within the runoff generation model; specifically the inclusion of both saturation excess and Horton infiltration excess runoff production mechanisms. The dominance of these mechanisms over different return periods of the flood frequency distribution can significantly affect the distributional shape and confidence limits about the distribution. Comparisons with observed flood distributions seem to indicate that such mixed runoff production mechanisms influence flood distribution shape. The

  20. Critical evaluation of the nonradiological environmental technical specifications. Volume 4. San Onofre Nuclear Generating Station, Unit 1

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.M.; Cunningham, P.A.; Gray, D.D.; Kumar, K.D.

    1976-08-10

    A comprehensive study of the data collected as part of the environmental Technical Specifications program for Unit 1 of the San Onofre Nuclear Generating Station (SONGS 1) was conducted for the Office of Nuclear Regulatory Research of the U.S. Nuclear Regulatory Commission. The program included an analysis of the hydrothermal and ecological monitoring data collected during 1975. The hydrothermal analysis includes a discussion of models used in plume predictions prior to plant operation and an evaluation of the present hydrothermal monitoring program. The ecological evaluation was directed toward reviewing the strengths and weaknesses of the various sampling programs designed to monitor the planktonic, benthic, and nektonic communities inhabiting the inshore coastal area in the vicinity of San Onofre.

  1. Reliability of hydroelectric generation components, systems and units; Confiabilidad de componentes, sistemas y unidades de generacion hidroelectrica

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Sanchez, Ramon; Torres Toledano, Gerardo; Franco Nava, Jose Manuel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    This article presents a methodology for the calculation of the reliability of components, systems and hydroelectric generating units, as well as the scope of a computational system for the evaluation of such reliability. In the case of the reliability calculation of components and systems, the computer programs is not limited to hydro stations and can be used in other type of systems. [Espanol] En este articulo se presenta una metodologia para calcular la confiabilidad de componentes, sistemas y unidades de generacion hidroelectrica, asi como el alcance de un sistema computacional para evaluar dicha confiabilidad. En el caso del calculo de confiabilidad de componentes y sistemas, el programa de computo no se limita a centrales hidroelectricas y puede utilizarse en otro tipo de sistemas.

  2. Seismic structural fragility investigation for the San Onofre Nuclear Generating Station, Unit 1 (Project I); SONGS-1 AFWS Project

    Energy Technology Data Exchange (ETDEWEB)

    Wesley, D.A.; Hashimoto, P.S.

    1982-04-01

    An evaluation of the seismic capacities of several of the San Onofre Nuclear Generating Station, Unit 1 (SONGS-1) structures was conducted to determine input to the overall probabilistic methodology developed by Lawrence Livermore National Laboratory. Seismic structural fragilities to be used as input consist of median seismic capacities and their variabilities due to randomness and uncertainty. Potential failure modes were identified for each of the SONGS-1 structures included in this study by establishing the seismic load-paths and comparing expected load distributions to available capacities for the elements of each load-path. Particular attention was given to possible weak links and details. The more likely failure modes were screened for more detailed investigation.

  3. Subsea thermoelectric generators. 1- 10-watt peltier effect prototypes - a step towards autonomous electrical control units at subsea wellheads

    Energy Technology Data Exchange (ETDEWEB)

    Weid, J.P. von der; Silva, J.A.P. da; Gama, A.L.; Sant' Anna, A.C.

    1994-05-01

    Offshore oil production activities require the operation of underwater hydraulic or electric equipment. The high cost of acquisition and installation of umbilical cables to supply power is leading to the development of independently powered cableless equipment, connected to the surface by the transmission and reception of control signals through the water. As a first step toward these autonomous wellhead control systems, the authors designed and successfully tested in laboratory conditions a thermoelectric generator able to supply at least 10 watts of electric power, extracting it from the temperature difference between the oil and the surrounding water. Hydraulic pumps and pressure accumulators, control electronics, and valve actuators for wellhead control units are all technically solved problems, even for seafloors as deep as 1,000 meters. However, an autonomous underwater wellhead control unit can only be conceived if an energy source is available at the seafloor. The development of a reliable and compact power source is indeed a fundamental step towards autonomous wet Christmas tree valve actuators.

  4. Determining hydrodynamic forces in bursting bubbles using DNA nanotube mechanics

    Science.gov (United States)

    Hariadi, Rizal F.; Winfree, Erik; Yurke, Bernard

    2015-01-01

    Quantifying the mechanical forces produced by fluid flows within the ocean is critical to understanding the ocean’s environmental phenomena. Such forces may have been instrumental in the origin of life by driving a primitive form of self-replication through fragmentation. Among the intense sources of hydrodynamic shear encountered in the ocean are breaking waves and the bursting bubbles produced by such waves. On a microscopic scale, one expects the surface-tension–driven flows produced during bubble rupture to exhibit particularly high velocity gradients due to the small size scales and masses involved. However, little work has examined the strength of shear flow rates in commonly encountered ocean conditions. By using DNA nanotubes as a novel fluid flow sensor, we investigate the elongational rates generated in bursting films within aqueous bubble foams using both laboratory buffer and ocean water. To characterize the elongational rate distribution associated with a bursting bubble, we introduce the concept of a fragmentation volume and measure its form as a function of elongational flow rate. We find that substantial volumes experience surprisingly large flow rates: during the bursting of a bubble having an air volume of 10 mm3, elongational rates at least as large as ϵ˙=1.0×108 s−1 are generated in a fragmentation volume of ∼2×10−6 μL. The determination of the elongational strain rate distribution is essential for assessing how effectively fluid motion within bursting bubbles at the ocean surface can shear microscopic particles and microorganisms, and could have driven the self-replication of a protobiont. PMID:26504222

  5. Wind Energy in the United Kingdom: Modelling the Effect of Increases in Installed Capacity on Generation Efficiency

    CERN Document Server

    Stephens, Anthony D

    2016-01-01

    The decision by the United Kingdom (UK) government in 2007 that the country should build a 33GW wind fleet, capable of generating 25 percent of the UK electricity requirement, was controversial. Proponents argued that it was the most attractive means of lowering the UK greenhouse gas emissions, whereas opponents noted that it would result in an unnecessary and burdensome additional expense to industry and households. Subsequently there have been calls for the wind fleet target to be further increased to perhaps 50 percent of demand. Although the National Grid has had little difficulty in accommodating the current output of about 10 percent of the total demand on the grid, this will not be the case for a substantially larger wind fleet. When the wind blows strongly, turbines shed wind which is surplus to demand, leading to significant reductions in generating efficiency. The purpose of the research described in this paper has been to develop a method for investigating the likely performance of future large win...

  6. The excitation system of 727.5 MVA synchronous generator of the unit B1 in TPP 'Nikola Tesla B'

    Directory of Open Access Journals (Sweden)

    Ćirić Zoran

    2013-01-01

    Full Text Available This paper presents a technical solution for the replacement of the excitation system of the unit B1 in TPP 'Nikola Tesla B' as a part of the maintenance service in 2012. Since the generators of TPP 'Nikola Tesla B' have the greatest power in the power system of Serbia, it was necessary to achieve high reliability of the excitation system so that the process of producing electricity is not endangered Considering this, the implemented excitation system uses modern technology with redundancy both in the power and control blocks, which resulted in an increase in the hot reserve by 100%. In addition, it was necessary to adjust the excitation system to increased generator power and performance from 618MW to 667.5MW. In this paper, the main parameters of the excitation system are given: the power, the excitation system control, the thyristor ignition system, the event recorder system, the digital relay protection, as well as the measuring and signaling functions.

  7. DO THE FERMI GAMMA-RAY BURST MONITOR AND SWIFT BURST ALERT TELESCOPE SEE THE SAME SHORT GAMMA-RAY BURSTS?

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Eric; Briggs, Michael S. [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Connaughton, Valerie [Universities Space Research Association, Science and Technology Institute, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Lien, Amy [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Goldstein, Adam [NASA Postdoctoral Program, Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pelassa, Veronique [Smithsonian Astrophysical Observatory, P.O. Box 97, Amado, AZ 85645 (United States); Troja, Eleonora, E-mail: eb0016@uah.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-02-20

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  8. Does Twitter trigger bursts in signature collections?

    Directory of Open Access Journals (Sweden)

    Rui Yamaguchi

    Full Text Available INTRODUCTION: The quantification of social media impacts on societal and political events is a difficult undertaking. The Japanese Society of Oriental Medicine started a signature-collecting campaign to oppose a medical policy of the Government Revitalization Unit to exclude a traditional Japanese medicine, "Kampo," from the public insurance system. The signature count showed a series of aberrant bursts from November 26 to 29, 2009. In the same interval, the number of messages on Twitter including the keywords "Signature" and "Kampo," increased abruptly. Moreover, the number of messages on an Internet forum that discussed the policy and called for signatures showed a train of spikes. METHODS AND FINDINGS: In order to estimate the contributions of social media, we developed a statistical model with state-space modeling framework that distinguishes the contributions of multiple social media in time-series of collected public opinions. We applied the model to the time-series of signature counts of the campaign and quantified contributions of two social media, i.e., Twitter and an Internet forum, by the estimation. We found that a considerable portion (78% of the signatures was affected from either of the social media throughout the campaign and the Twitter effect (26% was smaller than the Forum effect (52% in total, although Twitter probably triggered the initial two bursts of signatures. Comparisons of the estimated profiles of the both effects suggested distinctions between the social media in terms of sustainable impact of messages or tweets. Twitter shows messages on various topics on a time-line; newer messages push out older ones. Twitter may diminish the impact of messages that are tweeted intermittently. CONCLUSIONS: The quantification of social media impacts is beneficial to better understand people's tendency and may promote developing strategies to engage public opinions effectively. Our proposed method is a promising tool to explore

  9. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    CERN Document Server

    Mingarelli, Chiara M F; Lazio, T Joseph W

    2015-01-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS--BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is $20\\%-80\\%$ as luminous, given 0.5~ms timing resolution. The main burst is from the peak luminosity before merger. The post-merger burst follows from the NS magnetic ...

  10. Models for Gamma-Ray Bursts and Diverse Transients

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, S.E.; /UC, Santa Cruz; Zhang, Weiqun; /KIPAC, Menlo Park

    2007-01-17

    The observational diversity of ''gamma-ray bursts'' (GRBs) has been increasing, and the natural inclination is a proliferation of models. We explore the possibility that at least part of this diversity is a consequence of a single basic model for the central engine operating in a massive star of variable mass, differential rotation rate, and mass loss rate. Whatever that central engine may be--and here the collapsar is used as a reference point--it must be capable of generating both a narrowly collimated, highly relativistic jet to make the GRB, and a wide angle, sub-relativistic outflow responsible for exploding the star and making the supernova bright. To some extent, the two components may vary independently, so it is possible to produce a variety of jet energies and supernova luminosities. We explore, in particular, the production of low energy bursts and find a lower limit, {approx} 10{sup 48} erg s{sup -1} to the power required for a jet to escape a massive star before that star either explodes or is accreted. Lower energy bursts and ''suffocated'' bursts may be particularly prevalent when the metallicity is high, i.e., in the modern universe at low redshift.

  11. Burst conditions of explosive volcanic eruptions recorded on microbarographs

    Science.gov (United States)

    Morrissey, M.M.; Chouet, B.A.

    1997-01-01

    Explosive volcanic eruptions generate pressure disturbances in the atmosphere that propagate away either as acoustic or as shock waves, depending on the explosivity of the eruption. Both types of waves are recorded on microbarographs as 1- to 0.1-hertz N-shaped signals followed by a longer period coda. These waveforms can be used to estimate burst pressures end gas concentrations in explosive volcanic eruptions and provide estimates of eruption magnitudes.

  12. Physics of gamma-ray bursts

    Science.gov (United States)

    Lamb, D. Q.

    1984-01-01

    Attention is given to the accumulating evidence for the view that gamma-ray bursts come from strongly magnetic neutron stars, discussing the physical properties of the emission region and the radiation processes expected in strong magnetic fields, and emphasizing that the observed burst spectra require that the emission region be optically thin. This entails that the energy of the emitting plasma and/or the plasma itself be continuously replenished during a burst, and that the cooling time scale of the emitting plasma be much shorter than the observed duration of the bursts. This characteristic of the cooling time scale implies that the burst intensity and spectrum can vary on extremely short time scales, and that the burst duration must have a separate explanation. It is emphasized that synchrotron emission is favored as the gamma-ray production mechanism; it is the only mechanism capable of satisfying the optical thinness constraint while producing the observed luminosity.

  13. Statistics of gamma ray burst temporal asymmetry

    CERN Document Server

    Link, B; Link, Bennett; Epstein, Richard

    1996-01-01

    We study the temporal asymmetry of over 600 bursts from the BATSE 3B catalog, encompassing a 200-fold range in peak flux. By comparing the rates of rise and fall of the flux near the highest burst peak, we find that about two-thirds of the bursts exhibit a preferred asymmetry in the sense that the flux rises more rapidly than it falls, confirming the conclusions of previous studies employing smaller databases. The statistical significance of the average time asymmetry of the sample is >99.999\\%; therefore, models that predict time symmetry of the burst profile are ruled out. We find no statistically significant correlation between burst temporal asymmetry and peak. This result is consistent with both cosmological and local interpretations of the gamma ray burst phenomenon.

  14. Stirling Colgate and Gamma-Ray Bursts

    Science.gov (United States)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  15. Hardness/intensity correlations among BATSE bursts

    Science.gov (United States)

    Paciesas, William S.; Pendleton, Geoffrey N.; Kouveliotou, Chryssa; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1992-01-01

    Conclusions about the nature of gamma-ray bursts derived from the size-frequency distribution may be altered if a significant correlation exists between burst intensity and spectral shape. Moreover, if gamma-ray bursts have a cosmological origin, such a correlation may be expected to result from the expansion of the universe. We have performed a rudimentary search of the BATSE bursts for hardness/intensity correlations. The range of spectral shapes was determined for each burst by computing the ratio of the intensity in the range 100-300 keV to that in 55-300 keV. We find weak evidence for the existence of a correlation, the strongest effect being present when comparing the maximum hardness ratio for each burst with its maximum rate.

  16. Three types of $\\gamma$-ray bursts

    CERN Document Server

    Mukherjee, S; Babu, G J; Murtagh, F; Fraley, C; Raftery, A E; Mukherjee, Soma; Feigelson, Eric D.; Babu, Gutti Jogesh; Murtagh, Fionn; Fraley, Chris; Raftery, Adrian

    1998-01-01

    A multivariate analysis of gamma-ray burst (GRB) bulk properties is presented to discriminate between distinct classes of GRBs. Several variables representing burst duration, fluence and spectral hardness are considered. Two multivariate clustering procedures are used on a sample of 797 bursts from the Third BATSE Catalog: a nonparametric average linkage hierarchical agglomerative clustering procedure validated with Wilks' $\\Lambda^*$ and other MANOVA tests; and a parametric maximum likelihood model-based clustering procedure assuming multinormal populations calculated with the EM Algorithm and validated with the Bayesian Information Criterion. The two methods yield very similar results. The BATSE GRB population consists of three classes with the following Duration/Fluence/Spectrum bulk properties: Class I with long/bright/intermediate bursts, Class II with short/hard/faint bursts, and Class III with intermediate/intermediate/soft bursts. One outlier with poor data is also present. Classes I and II correspond...

  17. Pulse Phase Dependence of the Magnetar Bursts

    Indian Academy of Sciences (India)

    Chetana Jain; Anjan Dutta; Biswajit Paul

    2007-12-01

    We report here results from a study of X-ray bursts from 3 magnetar candidates (SGR 1806–20, SGR 1900+14 and AXP 1E 2259+586). We have searched for a pulse phase dependence of the X-ray burst rate from these sources. X-ray light curves were obtained with the Proportional Counter Array on-board the Rossi X-ray Timing Explorer during the periods of intense burst activity in these sources. On detailed analysis of the three sources, we found a very significant burst rate for all pulsar phases. However, some locations appear to produce bursts slightly more often, rendering the non-isotropic distribution. Only in the case of SGR 1900+14, there is a clear pulse phase dependence of burst rate.

  18. BudBurst Buddies: A New Tool for Engaging the Youngest Citizen Scientists

    Science.gov (United States)

    Gardiner, L. S.; Henderson, S.; Ward, D.

    2010-12-01

    BudBurst Buddies (www.budburstbuddies.org) introduces elementary school age children to the science of observing plants and the timing of phenological (life cycle) events. BudBurst Buddies is a new part of the Project BudBurst national citizen science initiative (www.budburst.org), which allows individuals to engage in the scientific process, contributing to a better understanding of climate change while increasing public awareness of phenology and the impacts of climate change on plants. As a first step towards engaging the next generation of citizen scientists, BudBurst Buddies provides the opportunity for children to gain experience with scientific research and increases awareness of how plants change throughout the year. Children can participate in BudBurst Buddies on their own, with their families, or in formal or informal education settings. Each child who participates creates a journal about a plant of his or her choosing, makes observations of the plant over the growing season and submits findings online, earning an official BudBurst Buddies certificate. An online storybook for kids tells how two children, Lily and Sage, observed plants in their neighborhood and became BudBurst Buddies. This presentation will provide an overview of the BudBurst Buddies newly developed resources. BudBurst Buddies is a part of Project BudBurst, a national citizen science program coordinated by the National Ecological Observatory Network (NEON) and the Chicago Botanic Garden. Funding for this resource was provided by NEON, NSF, NASA, and the National Geographic Education Foundation.

  19. Ballerina - pirouettes in search of gamma bursts

    Science.gov (United States)

    Brandt, S.; Lund, N.; Pedersen, H.; Hjorth, J.; BALLERINA Collaboration

    1999-09-01

    The cosmological origin of gamma ray bursts has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX.

  20. Fast Radio Burst/Gamma-Ray Burst Cosmography

    Science.gov (United States)

    Gao, He; Li, Zhuo; Zhang, Bing

    2014-06-01

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM_{IGM} as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value \\lt {DM_IGM} (z)\\gt and luminosity distance (D L(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate \\lt {DM_IGM} (z)\\gt using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  1. Fast radio burst/gamma-ray burst cosmography

    Energy Technology Data Exchange (ETDEWEB)

    Gao, He; Zhang, Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States); Li, Zhuo, E-mail: gaohe@physics.unlv.edu, E-mail: zhang@physics.unlv.edu, E-mail: zhuo.li@pku.edu.cn [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)

    2014-06-20

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM{sub IGM} as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D {sub L}(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  2. Bubble bursting as an aerosol generation mechanism during an oil spill in the deep-sea environment: molecular dynamics simulations of oil alkanes and dispersants in atmospheric air/salt water interfaces.

    Science.gov (United States)

    Liyana-Arachchi, Thilanga P; Zhang, Zenghui; Ehrenhauser, Franz S; Avij, Paria; Valsaraj, Kalliat T; Hung, Francisco R

    2014-01-01

    Potential of mean force (PMF) calculations and molecular dynamics (MD) simulations were performed to investigate the properties of oil n-alkanes [i.e., n-pentadecane (C15), n-icosane (C20) and n-triacontane (C30)], as well as several surfactant species [i.e., the standard anionic surfactant sodium dodecyl sulfate (SDS), and three model dispersants similar to the Tween and Span species present in Corexit 9500A] at air/salt water interfaces. This study was motivated by the 2010 Deepwater Horizon (DWH) oil spill, and our simulation results show that, from the thermodynamic point of view, the n-alkanes and the model dispersants have a strong preference to remain at the air/salt water interface, as indicated by the presence of deep free energy minima at these interfaces. The free energy minimum of these n-alkanes becomes deeper as their chain length increases, and as the concentration of surfactant species at the interface increases. The n-alkanes tend to adopt a flat orientation and form aggregates at the bare air/salt water interface. When this interface is coated with surfactants, the n-alkanes tend to adopt more tilted orientations with respect to the vector normal to the interface. These simulation results are consistent with the experimental findings reported in the accompanying paper [Ehrenhauser et al., Environ. Sci.: Processes Impacts 2013, in press, (DOI: 10.1039/c3em00390f)]. The fact that these long-chain n-alkanes show a strong thermodynamic preference to remain at the air/salt water interfaces, especially if these interfaces are coated with surfactants, makes these species very likely to adsorb at the surface of bubbles or droplets and be ejected to the atmosphere by sea surface processes such as whitecaps (breaking waves) and bubble bursting. Finally, the experimental finding that more oil hydrocarbons are ejected when Corexit 9500A is present in the system is consistent with the deeper free energy minima observed for the n-alkanes at the air/salt water

  3. Inhibitory activity of lipid fractions myobacterium avium complex against macrophage respiratory burst

    OpenAIRE

    Shimizu, Toshiaki; 冨岡, 治明

    1998-01-01

    To explore possible mechanisms of the resistance of Mycobacterium avium complex (MAC) intracellular parasites to the antimicrobial activity of macrophages (MΦs), effects of the lipid components of these parasites on the MΦ respiratory burst were investigated. In this study, the MΦ respiratory burst was measured by luminoldependent chemiluminescence generated through the peroxidase-mediated halogenation reaction in murine peritoneal MΦs in response to phorbol myristate acetate (PMA) triggering...

  4. All Sky Search for Gravitational-Wave Bursts in the Second Joint LIGO-Virgo Run

    Science.gov (United States)

    Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Ceron, E. Amador; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. A.; Araya, M. C.; Aylott, B. E.; Blackburn, L.; Camp, J. B.; Cannizzo, J.

    2012-01-01

    We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration approx. sky search for generic gravitational-wave bursts and synthesizes the results achieved by the initial generation of interferometric detectors.

  5. Two classes of gamma-ray bursts

    CERN Document Server

    Katz, J I

    1995-01-01

    Data from the 3B Catalogue suggest that short and long GRB are the results of different classes of events, rather than different parameter values within a single class: Short bursts have harder spectra in the BATSE bands, but chiefly long bursts are detected at photon energies over 1 MeV, implying that their hard photons are radiated by a process not found in short bursts. The values of \\langle V/V_{max} \\rangle for short and long bursts differ by 4.3 \\sigma, implying different spatial distributions. Only the soft gamma-ray radiation mechanisms are the same in both classes.

  6. Bubble burst as jamming phase transition

    CERN Document Server

    Nishinari, Katsuhiro; Saito, Yukiko Umeno; Watanabe, Tsutomu

    2010-01-01

    Recently research on bubble and its burst attract much interest of researchers in various field such as economics and physics. Economists have been regarding bubble as a disorder in prices. However, this research strategy has overlooked an importance of the volume of transactions. In this paper, we have proposed a bubble burst model by focusing the transactions incorporating a traffic model that represents spontaneous traffic jam. We find that the phenomenon of bubble burst shares many similar properties with traffic jam formation by comparing data taken from US housing market. Our result suggests that the transaction could be a driving force of bursting phenomenon.

  7. Analysis of historic bursts and burst detection in water supply areas of different size

    NARCIS (Netherlands)

    Bakker, M.; Trietsch, E.A.; Vreeburg, J.H.G.; Rietveld, L.C.

    2014-01-01

    Pipe bursts in water distribution networks lead to water losses and a risk of damaging the urban environment. We studied hydraulic data and customer contact records of 44 real bursts for a better understanding of the phenomena. We found that most bursts were reported to the water company shortly aft

  8. Recent results of zebra patterns in solar radio bursts

    Institute of Scientific and Technical Information of China (English)

    Gennady P.Chernov

    2010-01-01

    This review covers the most recent experimental results and theoretical research on zebra patterns(ZPs)in solar radio bursts.The basic attention is given to events with new peculiar elements of zebra patterns received over the last few years.All new properties are considered in light of both what was known earlier and new theoretical models.Large-scale ZPs consisting of small-scale fiber bursts could be explained by simultaneous inclusion of two mechanisms when whistler waves"highlight"the levels of double plasma resonance(DPR).A unique fine structure was observed in the event on 2006 December 13: spikes in absorption formed dark ZP stripes against the absorptive type Ⅲ-like bursts.The spikes in absorption can appear in accordance with well known mechanisms of absorptive bursts.The additional injection of fast particles filled the loss-cone(breaking the loss-cone distribution),and the generation of the continuum was quenched at these moments.The maximum absorptive effect occurs at the DPR levels.The parameters of millisecond spikes are determined by small dimensions of the particle beams and local scale heights in the radio source.Thus,the DPR model helps to understand several aspects of unusual elements of ZPs.However,the simultaneous existence of several tens of the DPR levels in the corona is impossible for any realistic profile of the plasma density and magnetic field.Three new theories of ZPs are examined.The formation of eigenmodes of transparency and opacity during the propagation of radio waves through regular coronal inhomogeneities is the most natural and promising mechanism.Two other models(nonlinear periodic space-charge waves and scattering of fast protons on ion-sound harmonics)could happen in large radio bursts.

  9. A non-Mendelian MAPK-generated hereditary unit controlled by a second MAPK pathway in Podospora anserina.

    Science.gov (United States)

    Lalucque, Hervé; Malagnac, Fabienne; Brun, Sylvain; Kicka, Sébastien; Silar, Philippe

    2012-06-01

    The Podospora anserina PaMpk1 MAP kinase (MAPK) signaling pathway can generate a cytoplasmic and infectious element resembling prions. When present in the cells, this C element causes the crippled growth (CG) cell degeneration. CG results from the inappropriate autocatalytic activation of the PaMpk1 MAPK pathway during growth, whereas this cascade normally signals stationary phase. Little is known about the control of such prion-like hereditary units involved in regulatory inheritance. Here, we show that another MAPK pathway, PaMpk2, is crucial at every stage of the fungus life cycle, in particular those controlled by PaMpk1 during stationary phase, which includes the generation of C. Inactivation of the third P. anserina MAPK pathway, PaMpk3, has no effect on the development of the fungus. Mutants of MAPK, MAPK kinase, and MAPK kinase kinase of the PaMpk2 pathway are unable to present CG. This inability likely relies upon an incorrect activation of PaMpk1, although this MAPK is normally phosphorylated in the mutants. In PaMpk2 null mutants, hyphae are abnormal and PaMpk1 is mislocalized. Correspondingly, stationary phase differentiations controlled by PaMpk1 are defective in the mutants of the PaMpk2 cascade. Constitutive activation of the PaMpk2 pathway mimics in many ways its inactivation, including an effect on PaMpk1 localization. Analysis of double and triple mutants inactivated for two or all three MAPK genes undercover new growth and differentiation phenotypes, suggesting overlapping roles. Our data underscore the complex regulation of a prion-like element in a model organism.

  10. Magnetars and Gamma Ray Bursts

    CERN Document Server

    Bucciantini, N

    2012-01-01

    In the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I will review here the key aspects of the {\\it millisecond magnetar} model for Long Duration Gamma Ray Bursts (LGRBs). I will briefly describe what constraints, present observations put on any engine model, both in term of energetic, outflow properties, and the relation with the associated Supernova (SN). For each of these I will show how the millisecond magnetar model satisfies the requirements, what are the limits of the model, how can it be further tested, and what observations might be used to discriminate against it. I will also discuss numerical results that show the importance of the confinement by the progenitor star in explaining the formation of a collimated outflow, how a detailed model for the evolution of the central engine can be built, and show that a wide varie...

  11. Coronal magnetic fields from multiple type II bursts

    Science.gov (United States)

    Honnappa, Vijayakumar; Raveesha, K. H.; Subramanian, K. R.

    Coronal magnetic fields from multiple type II bursts Vijayakumar H Doddamani1*, Raveesha K H2 and Subramanian3 1Bangalore University, Bangalore, Karnataka state, India 2CMR Institute of Technology, Bangalore, Karnataka state, India 3 Retd, Indian Institute of Astrophysics, Bangalore, Karnataka state, India Abstract Magnetic fields play an important role in the astrophysical processes occurring in solar corona. In the solar atmosphere, magnetic field interacts with the plasma, producing abundant eruptive activities. They are considered to be the main factors for coronal heating, particle acceleration and the formation of structures like prominences, flares and Coronal Mass Ejections. The magnetic field in solar atmosphere in the range of 1.1-3 Rsun is especially important as an interface between the photospheric magnetic field and the solar wind. Its structure and time dependent change affects space weather by modifying solar wind conditions, Cho (2000). Type II doublet bursts can be used for the estimation of the strength of the magnetic field at two different heights. Two type II bursts occur sometimes in sequence. By relating the speed of the type II radio burst to Alfven Mach Number, the Alfven speed of the shock wave generating type II radio burst can be calculated. Using the relation between the Alfven speed and the mean frequency of emission, the magnetic field strength can be determined at a particular height. We have used the relative bandwidth and drift rate properties of multiple type II radio bursts to derive magnetic field strengths at two different heights and also the gradient of the magnetic field in the outer corona. The magnetic field strength has been derived for different density factors. It varied from 1.2 to 2.5 gauss at a solar height of 1.4 Rsun. The empirical relation of the variation of the magnetic field with height is found to be of the form B(R) = In the present case the power law index ‘γ’ varied from -3 to -2 for variation of

  12. Dependence of X-Ray Burst Models on Nuclear Reaction Rates

    Science.gov (United States)

    Cyburt, R. H.; Amthor, A. M.; Heger, A.; Johnson, E.; Keek, L.; Meisel, Z.; Schatz, H.; Smith, K.

    2016-10-01

    X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars, and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence of X-ray burst models on uncertainties in (p, γ), (α, γ), and (α, p) nuclear reaction rates using fully self-consistent burst models that account for the feedbacks between changes in nuclear energy generation and changes in astrophysical conditions. A two-step approach first identified sensitive nuclear reaction rates in a single-zone model with ignition conditions chosen to match calculations with a state-of-the-art 1D multi-zone model based on the Kepler stellar evolution code. All relevant reaction rates on neutron-deficient isotopes up to mass 106 were individually varied by a factor of 100 up and down. Calculations of the 84 changes in reaction rate with the highest impact were then repeated in the 1D multi-zone model. We find a number of uncertain reaction rates that affect predictions of light curves and burst ashes significantly. The results provide insights into the nuclear processes that shape observables from X-ray bursts, and guidance for future nuclear physics work to reduce nuclear uncertainties in X-ray burst models.

  13. Blueshifting may explain the gamma ray bursts

    CERN Document Server

    Krasiński, Andrzej

    2015-01-01

    It is shown that the basic observed properties of the gamma-ray bursts (GRBs) are accounted for if one assumes that the GRBs arise by blueshifting the emission radiation of hydrogen and helium generated during the last scattering epoch. The blueshift generator for a single GRB is a Lema\\^{\\i}tre -- Tolman (L--T) region with a nonconstant bang-time function $t_B(r)$ matched into a Friedmann background. Blueshift visible to the observer arises \\textit{only on radial rays} that are emitted in the L--T region. The paper presents three L--T models with different Big Bang profiles, adapted for the highest and the lowest end of the GRB frequency range. The models account for: (1) The observed frequency range of the GRBs; (2) Their limited duration; (3) The afterglows; (4) Their hypothetical collimation into narrow jets; (5) The large distances to their sources; (6) The multitude of the observed GRBs. Properties (2), (3) and (6) are accounted for only qualitatively. With a small correction of the parameters of the mo...

  14. Do the Fermi Gamma-Ray Burst Monitor and Swift Burst Alert Telescope see the Same Short Gamma-Ray Bursts?

    CERN Document Server

    Burns, Eric; Zhang, Bin-Bin; Lien, Amy; Briggs, Michael S; Goldstein, Adam; Pelassa, Veronique; Troja, Eleonora

    2015-01-01

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field-of-view, and that the Fermi GBM SGRB detection threshold remains flatter across its field-of-view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and...

  15. 76 FR 24064 - Arizona Public Service Company, Palo Verde Nuclear Generating Station, Units 1, 2, and 3, Notice...

    Science.gov (United States)

    2011-04-29

    ... supercritical coal-fired generation; natural gas combined-cycle generation; new nuclear generation; a... water reactors located in Maricopa County, Arizona. The application for the renewed licenses complied...

  16. Composition Modeling and Equivalence of an Integrated Power Generation System of Wind, Photovoltaic and Energy Storage Unit

    Institute of Scientific and Technical Information of China (English)

    WANG Haohuai; TANG Yong; HOU Junxian; ZOU Jiangfeng; LIANGShuang; SU Feng

    2011-01-01

    The characteristic of wind and solar generation is random and fluctuant. In order to improve their generation performance, the integrated power generation of wind, photovoltaic (PV) and energy storage is a focus in the study. In this paper,

  17. Coronal Magnetic Field Lines and Electrons Associated with Type III–V Radio Bursts in a Solar Flare

    Indian Academy of Sciences (India)

    P. Kishore; C. Kathiravan; R. Ramesh; E. Ebenezer

    2017-06-01

    We recently investigated some of the hitherto unreported observational characteristics of the low frequency (85–35 MHz) type III–V bursts from the Sun using radio spectropolarimeter observations. The quantitative estimates of the velocities of the electron streams associated with the above two types of bursts indicate that they are in the range ${\\gtrsim }0.13c–0.02c$ for the type V bursts, and nearly constant (${\\approx }0.4c$) for the type III bursts. We also find that the degree of circular polarization of the type V bursts vary gradually with frequency/heliocentric distance as compared to the relatively steeper variation exhibited by the preceding type III bursts. These imply that the longer duration of the type V bursts at any given frequency (as compared to the preceding type III bursts) which is its defining feature, is due to the combined effect of the lower velocities of the electron streams that generate type V bursts, spread in the velocity spectrum, and the curvature of the magnetic field lines along which they travel.

  18. Coding Bounds for Multiple Phased-Burst Correction and Single Burst Correction Codes

    CERN Document Server

    Fong, Wai Han

    2011-01-01

    In this paper, two upper bounds on the achievable code rate of linear block codes for multiple phased-burst correction (MPBC) are presented. One bound is constrained to a maximum correctable cyclic burst length within every subblock, or equivalently a constraint on the minimum error free length or gap within every phased-burst. This bound, when reduced to the special case of a bound for single burst correction (SBC), is shown to be the Abramson bound when the cyclic burst length is less than half the block length. The second MPBC bound is developed without the minimum error free gap constraint and is used as a comparison to the first bound.

  19. Coupling and noise induced spiking-bursting transition in a parabolic bursting model.

    Science.gov (United States)

    Ji, Lin; Zhang, Jia; Lang, Xiufeng; Zhang, Xiuhui

    2013-03-01

    The transition from tonic spiking to bursting is an important dynamic process that carry physiologically relevant information. In this work, coupling and noise induced spiking-bursting transition is investigated in a parabolic bursting model with specific discussion on their cooperation effects. Fast/slow analysis shows that weak coupling may help to induce the bursting by changing the geometric property of the fast subsystem so that the original unstable periodical solution are stabilized. It turned out that noise can play the similar stabilization role and induce bursting at appropriate moderate intensity. However, their cooperation may either strengthen or weaken the overall effect depending on the choice of noise level.

  20. Using temporal bursts for query modeling

    NARCIS (Netherlands)

    Peetz, M.H.; Meij, E.; de Rijke, M.

    2014-01-01

    We present an approach to query modeling that leverages the temporal distribution of documents in an initially retrieved set of documents. In news-related document collections such distributions tend to exhibit bursts. Here, we define a burst to be a time period where unusually many documents are pu

  1. Photospheric radius expansion during magnetar bursts

    NARCIS (Netherlands)

    A.L. Watts; C. Kouveliotou; A.J. van der Horst; E. Göğüş; Y. Kaneko; M. van der Klis; R.A.M.J. Wijers; A.K. Harding; M.G. Baring

    2010-01-01

    On 2008 August 24 the new magnetar SGR 0501+4516 (discovered by Swift) emitted a bright burst with a pronounced double-peaked structure in hard X-rays, reminiscent of the double-peaked temporal structure seen in some bright thermonuclear bursts on accreting neutron stars. In the latter case this is

  2. Astronomy: Radio burst caught red-handed

    Science.gov (United States)

    Falcke, Heino

    2017-01-01

    For almost a decade, astronomers have observed intense bursts of radio waves from the distant cosmos whose origins were unknown. The source of one such burst has now been identified, but this has only deepened the mystery. See Letter p.58

  3. IMAGING DIAGNOSIS OF THORACOLUMBAR BURST FRACTURES

    Institute of Scientific and Technical Information of China (English)

    Li-yang Dai

    2004-01-01

    Objective To review imaging use in the diagnosis ofthoracolumbar burst fractures and to determine the diagnostic value of different imaging methods.Methods One hundred and fourteen patients with 120 thoracolumbar burst fractures were retrospectively reviewed. Plain radiographs were available in all cases; CT scans and MRI were obtained in 96 and 74 cases, respectively.Results A total of 27 burst fractures were misdiagnosed as other types of fractures on radiographs alone, and accounted for 22.5% of all fractures. The results indicated that plain radiographs often fail to delineate the pathological features of thoracolumbar burst fractures, leading to delay in diagnosis.Conclusion In regard to thoracolumbar injury diagnosis, burst fractures should be differentiated from compression fractures. CT should be routinely indicated and MRI examination, when necessary, may be simultaneously considered.

  4. FRBCAT: The Fast Radio Burst Catalogue

    Science.gov (United States)

    Petroff, E.; Barr, E. D.; Jameson, A.; Keane, E. F.; Bailes, M.; Kramer, M.; Morello, V.; Tabbara, D.; van Straten, W.

    2016-09-01

    Here, we present a catalogue of known Fast Radio Burst sources in the form of an online catalogue, FRBCAT. The catalogue includes information about the instrumentation used for the observations for each detected burst, the measured quantities from each observation, and model-dependent quantities derived from observed quantities. To aid in consistent comparisons of burst properties such as width and signal-to-noise ratios, we have re-processed all the bursts for which we have access to the raw data, with software which we make available. The originally derived properties are also listed for comparison. The catalogue is hosted online as a Mysql database which can also be downloaded in tabular or plain text format for off-line use. This database will be maintained for use by the community for studies of the Fast Radio Burst population as it grows.

  5. 78 FR 63506 - Exelon Generation Company, LLC; Peach Bottom Atomic Power Station, Units 2 and 3; Proposed...

    Science.gov (United States)

    2013-10-24

    .... Units 2 and 3 at PBAPS have a common once-through heat dissipation system that draws water from and..., and as a source of public water. Units 2 and 3 use six circulating water pumps (three per unit), each... canal. Three adjustable discharge gates at the end of the discharge canal control the flow to Conowingo...

  6. Methods of rock burst prediction

    Energy Technology Data Exchange (ETDEWEB)

    Genkin, V.A.; Minin, Yu.Ya.; Morozov, G.D.; Proskuryakov, V.M.; Cmirnov, V.A.

    1979-07-01

    Some methods of predicting rock bursts in underground coal and iron ore mines are evaluated: using BP-18 indenters and the MGD indenter with automatic recording; seismic method consisting in measuring the speed of shock waves travelling through various layers (apparatus SB-20 is designed for use in coal mines); electrometric method (measuring resistance between two electrodes when electric currents flow through coal and rocks). The design of the AEhSSh-1 measuring instrument, used in the electrometric method in coal mines is also described. Each of the methods is described and mathematical fomulae used as their theoretical basis are presented. The calculating process is explained and brief information on the design and use of the measuring instrument is given. The methods are evaluated from the viewpoint of precision. (In Russian)

  7. Fast Mapping of Terahertz Bursting Thresholds and Characteristics at Synchrotron Light Sources

    CERN Document Server

    Brosi, Miriam; Blomley, Edmund; Bründermann, Erik; Caselle, Michele; Hiller, Nicole; Kehrer, Benjamin; Nasse, Michael J; Rota, Lorenzo; Schedler, Manuel; Schönfeldt, Patrik; Schuh, Marcel; Schwarz, Markus; Weber, Marc; Müller, Anke-Susanne

    2016-01-01

    Dedicated optics with extremely short electron bunches enable synchrotron light sources to generate intense coherent THz radiation. The high degree of spatial compression in this so-called low-alpha optics entails a complex longitudinal dynamics of the electron bunches, which can be probed studying the fluctuations in the emitted terahertz radiation caused by the micro-bunching instability ("bursting"). This article presents a "quasi-instantaneous" method for measuring the bursting characteristics by simultaneously collecting and evaluating the information from all bunches in a multi-bunch fill, reducing the measurement time from hours to seconds. This speed-up allows systematic studies of the bursting characteristics for various accelerator settings within a single fill of the machine, enabling a comprehensive comparison of the measured bursting thresholds with theoretical predictions by the bunched-beam theory. This paper introduces the method and presents first results obtained at the ANKA synchrotron radi...

  8. Research and implementation of the burst-mode optical signal bit-error test

    Science.gov (United States)

    Huang, Qiu-yuan; Ma, Chao; Shi, Wei; Chen, Wei

    2009-08-01

    On the basis of the characteristic of TDMA uplink optical signal of PON system, this article puts forward a method of high-speed optical burst bit-error rate testing based on FPGA. The article proposes a new method of generating the burst signal pattern include user-defined pattern and pseudo-random pattern, realizes the slip synchronization, self-synchronization of error detection using data decomposition technique and the traditional irrigation code synchronization technology, completes high-speed burst signal clock synchronization using the rapid synchronization technology of phase-locked loop delay in the external circuit and finishes the bit-error rate test of high-speed burst optical signal.

  9. Rupture pressure of wear degraded alloy 600 steam generator tubings

    Science.gov (United States)

    Hwang, Seong Sik; Namgung, Chan; Jung, Man Kyo; Kim, Hong Pyo; Kim, Joung Soo

    2008-02-01

    Fretting/wear degradation at the tube support in the U-bend region of a steam generator (SG) of a pressurized water reactor (PWR) has been reported. Simulated fretted flaws were machined on SG tubes of 195 mm in length. A pressure test was carried out with the tubes at room temperature by using a high pressure test facility which consisted of a water pressurizing pump, a test specimen section and a control unit. Water leak rates just after a ligament rupture or a burst were measured. Tubes degraded by up to 70% of the tube wall thickness (TW) showed a high safety margin in terms of the burst pressure during normal operating conditions. Tubes degraded by up to 50% of the TW did not show burst. Burst pressure depended on the defect depths rather than on the wrap angles. The tube with a wrap angle of 0° showed a fish mouth fracture, whereas the tube with a 45° wrap angle showed a three way fracture.

  10. Energy consumption and distribution of 1 000 MW coal-fired power generating unit%1000MW燃煤机组能耗及其分布

    Institute of Scientific and Technical Information of China (English)

    杨志平; 杨勇平

    2012-01-01

    目前火力发电机组的性能分析方法仍基于热力学第一定律与第二定律,应用基于热力学第一定律的热量法和基于热力学第二定律的单耗分析法,以1 000 MW机组为研究对象,以机组设计参数进行建模分析,确定机组在不同工况下的发电煤耗及其在各个环节中的附加煤耗分布,并对评价方法进行比较,进而从设计层面分析机组的节能方向和潜力.%The current performance analysis method is still based on the first law and second law of thermodynamics a-bout Thermal power generating units. This paper used heat balance method based the first law of thermodynamics and the specific consumption analysis method based the second law of thermodynamics to analyze 1000MW power generating unit. Math model to the unit design parameters was established. Coal consumption and distribution in the different conditions and all aspects of the unit were determined. Compared with the evaluation methods, then the energy-saving direction and potentials of coal-fired generating unit from the design level was analyzed.

  11. The Complex Life Experience of First-Generation College Students Who Are Working Adults in the Appalachian Region of the United States: A Phenomenological Study

    Science.gov (United States)

    Thurman, Deborah Elizabeth

    2016-01-01

    The purpose of this transcendental phenomenological study was to describe and understand the complexity of life experiences for first-generation college students or recent graduates who are working adults in the Central and South-Central Appalachian region of the United States in light of the construct resilience and how purposefully selected…

  12. Modeling and Maximum Power Point Tracking Control of Wind Generating Units Equipped with Permanent Magnet Synchronous Generators in Presence of Losses

    Directory of Open Access Journals (Sweden)

    Andrea Bonfiglio

    2017-01-01

    Full Text Available This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results is proposed. Moreover, some analytical assessments are detailed on typical control schemes for fully rated wind turbine generators, thereby highlighting how active power losses play a fundamental role in the effectiveness of the wind generator control algorithm. Finally, the paper proposes analytical criteria to design the structure and the parameters of the regulators of the wind generator control scheme. Simulations performed with Digsilent Power Factory validated the proposed procedure, highlighting the impact of active power losses on the characterization of the initial steady state and that the simplifying assumptions done in order to synthesize the controllers are consistent with the complete modeling performed by the aforementioned power system simulator.

  13. Observational properties of decameter type IV bursts

    Science.gov (United States)

    Melnik, Valentin; Brazhenko, Anatoly; Rucker, Helmut; Konovalenko, Alexander; Briand, Carine; Dorovskyy, Vladimir; Zarka, Philippe; Frantzusenko, Anatoly; Panchenko, Michael; Poedts, Stefan; Zaqarashvili, Teimuraz; Shergelashvili, Bidzina

    2013-04-01

    Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated with CMEs. The largest periods of oscillations P were some tens of minutes. There were some modes of long periods of oscillations simultaneously. Periods of oscillations in flux and in polarization profiles were close. Detailed properties of oscillations at different frequencies were analyzed on the example of two type IV bursts. One of them was observed on April 7, 2011 when a CME happened. Another one (August 1, 2011) was registered without any CME. The 7 April type IV burst had two periods in the frames 75-85 and 35-85 minutes. Interesting feature of these oscillations is decreasing periods with time. The observed decreasing rates dP/dt equaled 0.03-0.07. Concerning type IV burst observed on August 1, 2011 the period of its oscillations increases from 17 min. at 30 MHz to 44 min. at 10 MHz. Connection of type IV burst oscillations with oscillations of magnetic arches and CMEs at corresponding altitudes are discussed. The work is fulfilled in the frame of FP7 project "SOLSPANET".

  14. Geothermal energy in the western United States and Hawaii: Resources and projected electricity generation supplies. [Contains glossary and address list of geothermal project developers and owners

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    Geothermal energy comes from the internal heat of the Earth, and has been continuously exploited for the production of electricity in the United States since 1960. Currently, geothermal power is one of the ready-to-use baseload electricity generating technologies that is competing in the western United States with fossil fuel, nuclear and hydroelectric generation technologies to provide utilities and their customers with a reliable and economic source of electric power. Furthermore, the development of domestic geothermal resources, as an alternative to fossil fuel combustion technologies, has a number of associated environmental benefits. This report serves two functions. First, it provides a description of geothermal technology and a progress report on the commercial status of geothermal electric power generation. Second, it addresses the question of how much electricity might be competitively produced from the geothermal resource base. 19 figs., 15 tabs.

  15. The Arecibo Fast Radio Burst: Dense Circum-burst Medium

    CERN Document Server

    Kulkarni, S R; Neill, J D

    2015-01-01

    The nature of fast radio bursts (FRB) has been extensively debated. Here we investigate FRB121102, detected at Arecibo telescope and remarkable for its unusually large spectral index. After extensive study we conclude that the spectral index is caused by a nebula with free-free absorption. We find that putative nebula must lie beyond the Milky Way. We conclude that FRBs are of extra-galactic origin and that they arise in dense star-forming regions. The challenge with extra-galactic models is the the high volumetric rate of FRBs. This high rate allows us to eliminate all models of catastrophic stellar deaths. Hyper-giant flares from young magnetars emerge as the most likely progenitors. Some of the consequences are: (i) Intergalactic FRB models can be safely ignored. (ii) The rich ISM environment of young magnetars can result in significant contribution to DM, Rotation Measure (RM) and in some cases to significant free-free optical depth. (iii) The star-forming regions in the host galaxies can contribute signi...

  16. Ballerina - pirouettes in search of gamma bursts

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik

    1999-01-01

    The cosmological origin of gamma ray bursts has now been established with reasonable certainty, Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are propo...... are proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX....

  17. 76 FR 388 - Southern Nuclear Operating Company; Vogtle Electric Generating Plant, Unit Nos. 1 and 2; Notice...

    Science.gov (United States)

    2011-01-04

    .... The resulting bending action constrains the tubes in the tubesheet thereby restricting primary- to... tube below the top of the steam generator tubesheet from periodic steam generator tube inspections for..., ``Steam Generator Tube lnspection Report'' to remove reference to previous interim alternate repair...

  18. Burst firing in a motion-sensitive neural pathway correlates with expansion properties of looming objects that evoke avoidance behaviours

    Directory of Open Access Journals (Sweden)

    Glyn Allan McMillan

    2015-12-01

    Full Text Available The locust visual system contains a well-defined motion-sensitive pathway that transfers visual input to motor centers involved in predator evasion and collision avoidance. One interneuron in this pathway, the descending contralateral movement detector (DCMD, is typically described as using rate coding; edge expansion of approaching objects causes an increased rate of neuronal firing that peaks after a certain retinal threshold angle is exceeded. However, evidence of intrinsic DCMD bursting properties combined with observable oscillations in mean firing rates and tight clustering of spikes in raw traces, suggest that bursting may be important for motion detection. Sensory neuron bursting provides important timing information about dynamic stimuli in many model systems, yet no studies have rigorously investigated if bursting occurs in the locust DCMD during object approach. We presented repetitions of 30 looming stimuli known to generate behavioural responses to each of 20 locusts in order to identify and quantify putative bursting activity in the DCMD. Overall, we found a bimodal distribution of inter-spike intervals (ISI with peaks of more frequent and shorter ISIs occurring from 1-8 ms and longer less frequent ISIs occurring from 40-50 ms. Subsequent analysis identified bursts and isolated single spikes from the responses. Bursting frequency increased in the latter phase of an approach and peaked at the time of collision, while isolated spiking was predominant during the beginning of stimulus approach. We also found that the majority of inter-burst intervals occurred at 40-50 ms (or 20-25 bursts/s. Bursting also occurred across varied stimulus parameters and suggests that burst timing may be a key component of looming detection. Our findings suggest that the DCMD uses two modes of coding to transmit information about looming stimuli and that these modes change dynamically with a changing stimulus at a behaviourally-relevant time.

  19. Turbulence comes in bursts in stably stratified flows

    CERN Document Server

    Rorai, C; Pouquet, A

    2013-01-01

    There is a clear distinction between simple laminar and complex turbulent fluids. But in some cases, as for the nocturnal planetary boundary layer, a stable and well-ordered flow can develop intense and sporadic bursts of turbulent activity which disappear slowly in time. This phenomenon is ill-understood and poorly modeled; and yet, it is central to our understanding of weather and climate dynamics. We present here a simple model which shows that in stably stratified turbulence, the stronger bursts can occur when the flow is expected to be more stable. The bursts are generated by a rapid non-linear amplification of energy stored in waves, and are associated with energetic interchanges between vertical velocity and temperature (or density) fluctuations. Direct numerical simulations on grids of 2048^3 points confirm this somewhat paradoxical result of measurably stronger events for more stable flows, displayed not only in the temperature and vertical velocity derivatives, but also in the amplitude of the field...

  20. TORTORA discovery of Naked-Eye Burst fast optical variability

    Science.gov (United States)

    Beskin, Grigory; Karpov, Sergey; Bondar, Sergey; Greco, Giuseppe; Guarnieri, Adriano; Bartolini, Corrado; Piccioni, Adalberto; Molinari, Emilio; Chincarini, Guido

    2008-10-01

    Features characterizing gamma-ray bursts in the different spectral bands may be a clue for the nature of their inner engine. Up to now, only several bursts have been observed in optical band during the gamma activity, and the only one-GRB080319B-was covered from rise till fall with high temporal resolution. Here we discuss these data, acquired with TORTORA fast wide-field monitoring optical camera, as well as results of its analysis. The camera observed the position of Naked-Eye Burst, GRB080318B, before, during and after the trigger. It detected the fast rise of optical emission, which reached the peak of V 5.3 at the eighteenth second, had a complex evolution till T+43s and monotonously faded then. The brightest part of the light curve contains two 15-20 s segments with different fluxes, each having two clearly-seen peaks of 5-8 s duration; all four peaks look quasi-periodic with separation of 9 s. There is no clear evidence of any sub-second variability. However, there are signs of quasi-periodic variability on 1s time scale at around the last peak (T+40 till T+50). The general properties of the optical light curve and its variability time scales look similar to the gamma one, but there is no clear correlation between them. This raises serious problems in interpretation of mechanisms generating such variability.

  1. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    Science.gov (United States)

    Mingarelli, Chiara; Levin, Janna; Lazio, Joseph

    2016-03-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs), NS-BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak. The main burst is from the peak luminosity before merger, while the post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS-BH pairs are desirable for ground-based gravitational wave (GW) observatories since the pair might not be detected any other way, with EM counterparts augmenting the scientific leverage beyond the GW signal. Valuably, EM signal can break degeneracies in the parameters encoded in the GW as well as probe the NS magnetic field strength, yielding insights into open problems in NS magnetic field decay.

  2. Intermittent bursts induced by double tearing mode reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Lai; Wang, Zheng-Xiong, E-mail: zxwang@dlut.edu.cn [Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2014-06-15

    Reversed magnetic shear (RMS) configuration is assumed to be the steady-state operation scenario for the future advanced tokamaks like International Thermonuclear Experimental Reactor. In this work, we numerically discover a phenomenon of violent intermittent bursts induced by self-organized double tearing mode (DTM) reconnection in the RMS configuration during the very long evolution, which may continuously lead to annular sawtooth crashes and thus badly impact the desired steady-state operation of the future advanced RMS tokamaks. The key process of the intermittent bursts in the off-axis region is similar to that of the typical sawtooth relaxation oscillation in the positive magnetic shear configuration. It is interestingly found that in the decay phase of the DTM reconnection, the zonal field significantly counteracts equilibrium field to make the magnetic shear between the two rational surfaces so weak that the residual self-generated vortices of the previous DTM burst are able to trigger a reverse DTM reconnection by curling the field lines.

  3. ESTIMATE OF BURSTING PRESSURE OF MILD STEEL PRESSURE VESSEL AND PRESENTATION OF BURSTING FORMULA

    Institute of Scientific and Technical Information of China (English)

    ZHENG Chuanxiang

    2006-01-01

    In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235(Gr.D) and 20R(1020) are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness.Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.

  4. Evolution of the bursting-layer wave during a Type 1 X-ray burst

    CERN Document Server

    Berkhout, R G

    2007-01-01

    In a popular scenario due to Heyl, quasi periodic oscillations (QPOs) which are seen during type 1 X-ray bursts are produced by giant travelling waves in neutron-star oceans. Piro and Bildsten have proposed that during the burst cooling the wave in the bursting layer may convert into a deep crustal interface wave, which would cut off the visible QPOs. This cut-off would help explain the magnitude of the QPO frequency drift, which is otherwise overpredicted by a factor of several in Heyl's scenario. In this paper, we study the coupling between the bursting layer and the deep ocean. The coupling turns out to be weak and only a small fraction of the surface-wave energy gets transferred to that of the crustal-interface wave during the burst. Thus the crustal-interface wave plays no dynamical role during the burst, and no early QPO cut-off should occur.

  5. Methodology and measures for preventing unacceptable flow-accelerated corrosion thinning of pipelines and equipment of NPP power generating units

    Science.gov (United States)

    Tomarov, G. V.; Shipkov, A. A.; Lovchev, V. N.; Gutsev, D. F.

    2016-10-01

    Problems of metal flow-accelerated corrosion (FAC) in the pipelines and equipment of the condensate- feeding and wet-steam paths of NPP power-generating units (PGU) are examined. Goals, objectives, and main principles of the methodology for the implementation of an integrated program of AO Concern Rosenergoatom for the prevention of unacceptable FAC thinning and for increasing operational flow-accelerated corrosion resistance of NPP EaP are worded (further the Program). A role is determined and potentialities are shown for the use of Russian software packages in the evaluation and prediction of FAC rate upon solving practical problems for the timely detection of unacceptable FAC thinning in the elements of pipelines and equipment (EaP) of the secondary circuit of NPP PGU. Information is given concerning the structure, properties, and functions of the software systems for plant personnel support in the monitoring and planning of the inservice inspection of FAC thinning elements of pipelines and equipment of the secondary circuit of NPP PGUs, which are created and implemented at some Russian NPPs equipped with VVER-1000, VVER-440, and BN-600 reactors. It is noted that one of the most important practical results of software packages for supporting NPP personnel concerning the issue of flow-accelerated corrosion consists in revealing elements under a hazard of intense local FAC thinning. Examples are given for successful practice at some Russian NPP concerning the use of software systems for supporting the personnel in early detection of secondary-circuit pipeline elements with FAC thinning close to an unacceptable level. Intermediate results of working on the Program are presented and new tasks set in 2012 as a part of the updated program are denoted. The prospects of the developed methods and tools in the scope of the Program measures at the stages of design and construction of NPP PGU are discussed. The main directions of the work on solving the problems of flow

  6. Gamma-Ray Burst Progenitors

    Science.gov (United States)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

  7. On Gamma-Ray Bursts

    CERN Document Server

    Ruffini, Remo; Bianco, Carlo Luciano; Caito, Letizia; Chardonnet, Pascal; Cherubini, Christian; Dainotti, Maria Giovanna; Fraschetti, Federico; Geralico, Andrea; Guida, Roberto; Patricelli, Barbara; Rotondo, Michael; Hernandez, Jorge Armando Rueda; Vereshchagin, Gregory; Xue, She-Sheng

    2008-01-01

    (Shortened) We show by example how the uncoding of Gamma-Ray Bursts (GRBs) offers unprecedented possibilities to foster new knowledge in fundamental physics and in astrophysics. After recalling some of the classic work on vacuum polarization in uniform electric fields by Klein, Sauter, Heisenberg, Euler and Schwinger, we summarize some of the efforts to observe these effects in heavy ions and high energy ion collisions. We then turn to the theory of vacuum polarization around a Kerr-Newman black hole, leading to the extraction of the blackholic energy, to the concept of dyadosphere and dyadotorus, and to the creation of an electron-positron-photon plasma. We then present a new theoretical approach encompassing the physics of neutron stars and heavy nuclei. It is shown that configurations of nuclear matter in bulk with global charge neutrality can exist on macroscopic scales and with electric fields close to the critical value near their surfaces. These configurations may represent an initial condition for the...

  8. Gamma-ray burst progenitors

    CERN Document Server

    Levan, Andrew; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-01-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; i) direct observations of GRBs and their host galaxies, ii) parameters derived from modeling, both via population synthesis and direct numerical simulation and iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous an...

  9. Gamma-ray Burst Cosmology

    CERN Document Server

    Wang, F Y; Liang, E W

    2015-01-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it...

  10. Bursting Smoke as an Infrared Countermeasure

    National Research Council Canada - National Science Library

    Amarjit Singh; P. J. Kamale; S. A. Joshi; L. K. Bankar

    1998-01-01

    ...) using cadmium-mercury-telluride (CMI) detector cooled by liquid nitrogen. The particle size and shape of the powders used in the bursting smokes were determined microscopically using Carl Zeiss Jena Neophot- 21...

  11. Expected Performance of the GLAST Burst Monitor

    Science.gov (United States)

    Meegan, Charles; Fishman, Gerald; Kouveliotou, Chryssa; Wilson-Hodge, Colleen; Paciesas, William; Preece, Robert; Briggs, Michael; Bhat, Narayana; Connaughton, Valerie; Greiner, Jochen; vonKienlin, Andreas; Diehl, Roland; Steinle, Helmut; Bissaldi, Elisabetta; Kippen, R. Marc

    2007-01-01

    The GLAST Burst Monitor (GBM) will enhance LAT observations of GRBs by extending the spectral coverage from the LAT threshold down to approx. 8 kev, and will provide a trigger for re-orienting the spacecraft to observe delayed emission from selected bursts outside the LAT field of view. GBM consists of twelve NaI scintillation detectors operating in the 8 kev to 1 MeV energy range and two BGO scintillation detectors operating in the 150 keV to 30 MeV energy range. Detector resolution, effective area, and angular response have been determined by calibrations. Analyses indicate that the on-board burst threshold will be approx. 0.7 photon/cm2/s and the on-board burst localization accuracy will typically be better than 8 degrees.

  12. Plasma Bursts in Deep Penetration Laser Welding

    Science.gov (United States)

    Mrňa, L.; Šarbort, M.

    We present an experimental study of the deep penetration laser welding process which aims to analyze the plasma plume oscillations on a short time scale. Using the high-speed camera we show that the plasma comes out of the keyhole in the form of short bursts rather than the continuous flow. We detect these bursts as the short-time intensity oscillations of light emissions coming from the plasma plume. We determine the period of bursts using the statistical signal processing methods and the short-time frequency analysis. Finally, we compare the characteristics of plasma bursts and the geometry of resulting welds carried out on a 2 kW Yb:YAG laser welding machine for the steel workpiece and various welding parameters settings.

  13. Long Burst Error Correcting Codes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long burst error mitigation is an enabling technology for the use of Ka band for high rate commercial and government users. Multiple NASA, government, and commercial...

  14. GLAST Burst Monitor Trigger Classification Algorithm

    Science.gov (United States)

    Perrin, D. J.; Sidman, E. D.; Meegan, C. A.; Briggs, M. S.; Connaughton, V.

    2004-01-01

    The Gamma Ray Large Area Space Telescope (GLAST), currently set for launch in the first quarter of 2007, will consist of two instruments, the GLAST Burst Monitor (GBM) and the Large Area Telescope (LAT). One of the goals of the GBM is to identify and locate gamma-ray bursts using on-board software. The GLAST observatory can then be re-oriented to allow observations by the LAT. A Bayesian analysis will be used to distinguish gamma-ray bursts from other triggering events, such as solar flares, magnetospheric particle precipitation, soft gamma repeaters (SGRs), and Cygnus X-1 flaring. The trigger parameters used in the analysis are the burst celestial coordinates, angle from the Earth's horizon, spectral hardness, and the spacecraft geomagnetic latitude. The algorithm will be described and the results of testing will be presented.

  15. FRBCAT: The Fast Radio Burst Catalogue

    CERN Document Server

    Petroff, E; Jameson, A; Keane, E F; Bailes, M; Kramer, M; Morello, V; Tabbara, D; van Straten, W

    2016-01-01

    Here we present a catalogue of known Fast Radio Burst (FRB) sources in the form of an online catalogue, FRBCAT. The catalogue includes information about the instrumentation used for the observations for each detected burst, the measured quantities from each observation, and model-dependent quantities derived from observed quantities. To aid in consistent comparisons of burst properties such as width and signal-to-noise ratios we have reprocessed all the bursts for which we have access to the raw data, with software which we make available. The originally derived properties are also listed for comparison. The catalogue is hosted online as a MySQL database which can also be downloaded in tabular or plain text format for off-line use. This database will be maintained for use by the community for studies of the FRB population as it grows.

  16. CMEs and frequency cutoff of solar bursts

    Science.gov (United States)

    Stanislavsky, Al.; Konovalenko, Al.; Koval, Ar.; Volvach, Y.; Zarka, P.

    2016-05-01

    Radio observations of solar bursts with high-frequency cutoff by the radio telescope UTR-2 (near Kharkiv, Ukraine) at 8-33 MHz on 17-19 August 2012 are presented. Such cutoff may be attributed to the emergence of the burst sources behind limb of the Sun with respect to an observer on the Earth. The events are strongly associated with solar eruptions occurred in a new active region. Ray tracing simulations show that the CMEs play a constructive role for the behind-limb bursts to be detected in ground-based observations. Likely, due to tunnel-like cavities with low density in CMEs, the radio emission of behind-limb solar bursts can be directed towards the Earth.

  17. Solar Micro-Type III Burst Storms and Long Dipolar Magnetic Field in the Outer Corona

    Science.gov (United States)

    Morioka, A.; Miyoshi, Y.; Iwai, K.; Kasaba, Y.; Masuda, S.; Misawa, H.; Obara, T.

    2015-08-01

    Solar micro-type III radio bursts are elements of the so-called type III storms and are characterized by short-lived, continuous, and weak emissions. Their frequency of occurrence with respect to radiation power is quite different from that of ordinary type III bursts, suggesting that the generation process is not flare-related, but due to some recurrent acceleration processes around the active region. We examine the relationship of micro-type III radio bursts with coronal streamers. We also explore the propagation channel of bursts in the outer corona, the acceleration process, and the escape route of electron beams. It is observationally confirmed that micro-type III bursts occur near the edge of coronal streamers. The magnetic field line of the escaping electron beams is tracked on the basis of the frequency drift rate of micro-type III bursts and the electron density distribution model. The results demonstrate that electron beams are trapped along closed dipolar field lines in the outer coronal region, which arise from the interface region between the active region and the coronal hole. A 22 year statistical study reveals that the apex altitude of the magnetic loop ranges from 15 to 50 RS. The distribution of the apex altitude has a sharp upper limit around 50 RS suggesting that an unknown but universal condition regulates the upper boundary of the streamer dipolar field.

  18. Research on experiment and calculation of foam bursting device

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This research presents experimental data on mechanical foam bursting device, based on the high speed of air fluid impinging insidethe foam bursting device, foam bubbles disrupted as a consequence of pressures changed very quickly as shear force and their impact forces. Experimental data on foam-bursting capacity have been presented. Designed device can provide effective foam bursting on collapse foam.

  19. The Five Year Fermi/GBM Magnetar Burst Catalog

    NARCIS (Netherlands)

    A.C. Collazzi; C. Kouveliotou; A.J. van der Horst; G.A. Younes; Y. Kaneko; E. Göğüş; L. Lin; J. Granot; M.H. Finger; V.L. Chaplin; D. Huppenkothen; A.L. Watts; A. von Kienlin; M.G. Baring; D. Gruber; P.N. Bhat; M.H. Gibby; N. Gehrels; J. Mcenery; M. van der Klis; R.A.M.J. Wijers

    2015-01-01

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here, we present

  20. Optimal Codes for the Burst Erasure Channel

    Science.gov (United States)

    Hamkins, Jon

    2010-01-01

    Deep space communications over noisy channels lead to certain packets that are not decodable. These packets leave gaps, or bursts of erasures, in the data stream. Burst erasure correcting codes overcome this problem. These are forward erasure correcting codes that allow one to recover the missing gaps of data. Much of the recent work on this topic concentrated on Low-Density Parity-Check (LDPC) codes. These are more complicated to encode and decode than Single Parity Check (SPC) codes or Reed-Solomon (RS) codes, and so far have not been able to achieve the theoretical limit for burst erasure protection. A block interleaved maximum distance separable (MDS) code (e.g., an SPC or RS code) offers near-optimal burst erasure protection, in the sense that no other scheme of equal total transmission length and code rate could improve the guaranteed correctible burst erasure length by more than one symbol. The optimality does not depend on the length of the code, i.e., a short MDS code block interleaved to a given length would perform as well as a longer MDS code interleaved to the same overall length. As a result, this approach offers lower decoding complexity with better burst erasure protection compared to other recent designs for the burst erasure channel (e.g., LDPC codes). A limitation of the design is its lack of robustness to channels that have impairments other than burst erasures (e.g., additive white Gaussian noise), making its application best suited for correcting data erasures in layers above the physical layer. The efficiency of a burst erasure code is the length of its burst erasure correction capability divided by the theoretical upper limit on this length. The inefficiency is one minus the efficiency. The illustration compares the inefficiency of interleaved RS codes to Quasi-Cyclic (QC) LDPC codes, Euclidean Geometry (EG) LDPC codes, extended Irregular Repeat Accumulate (eIRA) codes, array codes, and random LDPC codes previously proposed for burst erasure

  1. QoS-guaranteed burst transmission for VoIP service over optical burst switching networks

    Science.gov (United States)

    Tachibana, Takuji; Kasahara, Shoji

    2007-08-01

    We propose a burst transmission method that guarantees the voice over Internet protocol (VoIP) service. The proposed method consists of three techniques: round-robin burst assembly with slotted scheduling, priority control with void filling, and hop-based preemption. Each technique is utilized so that the burst loss probability and the burst transmission delay satisfy VoIP quality of service (QoS). We evaluate by simulation the performance of the proposed method in NSFNET with 14 nodes. Numerical examples show that our proposed method is effective for guaranteeing the VoIP QoS while accommodating a large number of VoIP users.

  2. Gamma-Ray Burst Class Properties

    Science.gov (United States)

    Hakkila, Jon; Haglin, David J.; Pendleton, Geoffrey N.; Mallozzi, Robert S.; Meegan, Charles A.; Roiger, Richard J.

    2000-01-01

    Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the Burst and Transient Source Experiment (BATSE) instrument, we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 (high fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E (sub peak) alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram.

  3. Phase analysis method for burst onset prediction

    Science.gov (United States)

    Stellino, Flavio; Mazzoni, Alberto; Storace, Marco

    2017-02-01

    The response of bursting neurons to fluctuating inputs is usually hard to predict, due to their strong nonlinearity. For the same reason, decoding the injected stimulus from the activity of a bursting neuron is generally difficult. In this paper we propose a method describing (for neuron models) a mechanism of phase coding relating the burst onsets with the phase profile of the input current. This relation suggests that burst onset may provide a way for postsynaptic neurons to track the input phase. Moreover, we define a method of phase decoding to solve the inverse problem and estimate the likelihood of burst onset given the input state. Both methods are presented here in a unified framework, describing a complete coding-decoding procedure. This procedure is tested by using different neuron models, stimulated with different inputs (stochastic, sinusoidal, up, and down states). The results obtained show the efficacy and broad range of application of the proposed methods. Possible applications range from the study of sensory information processing, in which phase-of-firing codes are known to play a crucial role, to clinical applications such as deep brain stimulation, helping to design stimuli in order to trigger or prevent neural bursting.

  4. Burst-suppression is reactive to photic stimulation in comatose children with acquired brain injury

    DEFF Research Database (Denmark)

    Nita, Dragos A.; Moldovan, Mihai; Sharma, Roy

    2016-01-01

    -suppression in children with acquired brain injury. Methods: Intensive care unit electroencephalographic monitoring recordings containing burst-suppression were obtained from 5 comatose children with acquired brain injury of various etiologies. Intermittent photic stimulation was performed at 1 Hz for 1 min to assess...

  5. Time Resolved Spectroscopy of SGR J1550-5418 Bursts Detected with Fermi/Gamma-Ray Burst Monitor

    NARCIS (Netherlands)

    Younes, G.; Kouveliotou, C.; van der Horst, A.J.; Baring, M.G.; Granot, J.; Watts, A.L.; Bhat, P.N.; Collazzi, A.; Gehrels, N.; Gorgone, N.; Göğüş, E.; Gruber, D.; Grunblatt, S.; Huppenkothen, D.; Kaneko, Y.; von Kienlin, A.; van der Klis, M.; Lin, L.; Mcenery, J.; van Putten, T.; Wijers, R.A.M.J.

    2014-01-01

    We report on a time-resolved spectroscopy of the 63 brightest bursts of SGR J1550-5418, detected with the Fermi/Gamma-ray Burst Monitor during its 2008-2009 intense bursting episode. We performed spectral analysis down to 4 ms timescales to characterize the spectral evolution of the bursts. Using a

  6. GRIPS - Gamma-Ray Burst Investigation via Polarimetry and Spectroscopy

    CERN Document Server

    Greiner, J

    2008-01-01

    The primary scientific goal of the GRIPS mission is to revolutionize our understanding of the early universe using gamma-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of gamma-ray energies (200 keV--50 MeV) and of polarimetry (200--1000 keV). Secondary goals achievable by this mission include direct measurements of supernova interiors through gamma-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near compact stars, interstellar shocks, and clusters of galaxies.

  7. Gamma-Ray Bursts as Sources of Strong Magnetic Fields

    CERN Document Server

    Granot, Jonathan; Bromberg, Omer; Racusin, Judith L; Daigne, Frédéric

    2015-01-01

    Gamma-Ray Bursts (GRBs) are the strongest explosions in the Universe, which due to their extreme character likely involve some of the strongest magnetic fields in nature. This review discusses the possible roles of magnetic fields in GRBs, from their central engines, through the launching, acceleration and collimation of their ultra-relativistic jets, to the dissipation and particle acceleration that power their $\\gamma$-ray emission, and the powerful blast wave they drive into the surrounding medium that generates their long-lived afterglow emission. An emphasis is put on particular areas in which there have been interesting developments in recent years.

  8. Search for neutrinos from gamma-ray bursts with ANTARES

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Julia [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics (ECAP), Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Collaboration: ANTARES Collaboration

    2014-11-18

    ANTARES is the largest high-energy neutrino telescope in the Northern Hemisphere. A search for neutrinos in coincidence with gamma-ray bursts using ANTARES data from late 2007 to 2011 is presented here. An extended maximum likelihood ratio search was employed to optimise the discovery potential for a neutrino signal as predicted by a second-generation numerical model. No significant excess was found, so 90% confidence upper limits on the fluences as expected from analytically approximated neutrino-emission models as well as on up-to-date numerical predictions were placed.

  9. Polarization in Gamma-Ray Bursts Produced by Pinch Discharge

    Institute of Scientific and Technical Information of China (English)

    Mei Wu; Li Chen; Ti-Pei Li

    2005-01-01

    Large-voltage, high-temperature plasma columns produced by pinch discharge can generate γ-ray flashes with energy spectra and spectral evolution consistent with what are observed in γ-ray bursts (GRBs), and the inverse Compton scattering (ICS) during the discharge process can produce high linear polarization. Our calculation indicates that the observed polarization depends on the angle between the line-of-sight to the GRB and the direction of the pinch discharge, but only weakly depends on observed γ-ray energy.

  10. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  11. Diversity of neural signals mediated by multiple, burst-firing mechanisms in rat olfactory tubercle neurons.

    Science.gov (United States)

    Chiang, Elizabeth; Strowbridge, Ben W

    2007-11-01

    Olfactory information is processed by a diverse group of interconnected forebrain regions. Most efforts to define the cellular mechanisms involved in processing olfactory information have been focused on understanding the function of the olfactory bulb, the primary second-order olfactory region, and its principal target, the piriform cortex. However, the olfactory bulb also projects to other targets, including the rarely studied olfactory tubercle, a ventral brain region recently implicated in regulating cocaine-related reward behavior. We used whole cell patch-clamp recordings from rat tubercle slices to define the intrinsic properties of neurons in the dense and multiform cell layers. We find three common firing modes of tubercle neurons: regular-spiking, intermittent-discharging, and bursting. Regular-spiking neurons are typically spiny-dense-cell-layer cells with pyramidal-shaped, dendritic arborizations. Intermittently discharging and bursting neurons comprise the majority of the deeper multiform layer and share a common morphology: multipolar, sparsely spiny cells. Rather than generating all-or-none stereotyped discharges, as observed in many brain areas, bursting cells in the tubercle generate depolarizing plateau potentials that trigger graded but time-limited discharges. We find two distinct subclasses of bursting cells that respond similarly to step stimuli but differ in the role transmembrane Ca currents play in their intrinsic behavior. Calcium currents amplify depolarizing inputs and enhance excitability in regenerative bursting cells, whereas the primary action of Ca in nonregenerative bursting tubercle neurons appears to be to decrease excitability by triggering Ca-activated K currents. Nonregenerative bursting cells exhibit a prolonged refractory period after even short discharges suggesting that they may function to detect transient events.

  12. NEXT GENERATION SOLVENT-MATERIALS COMPATIBILITY WITH POLYMER COMPONENTS WITHIN MODULAR CAUSTIC-SIDE SOLVENT EXTRACTION UNIT (FINAL REPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.; Peters, T.; Fink, S.

    2012-01-17

    The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The first deployment target for the technology is within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with organic polymers used in the facility. This report provides the data from exposing these polymers to the Next Generation Solvent (NGS). The test was conducted over six months. An assessment of the dimensional stability of polymers present in MCU (i.e., PEEK, Grafoil, Tefzel and Isolast) in the modified NGS (where the concentration of LIX{reg_sign}79 and MaxCalix was varied systematically) showed that LIX{reg_sign}79 selectively affected Tefzel and its different grades (by an increase in size and lowering its density). The copolymer structure of Tefzel and possibly its porosity allows for the easier diffusion of LIX{reg_sign}79. Tefzel is used as the seat material in some of the valves at MCU. Long term exposure to LIX{reg_sign}79, may make the valves hard to operate over time due to the seat material (Tefzel) increasing in size. However, since the physical changes of Tefzel in the improved solvent are comparable to the changes in the CSSX baseline solvent, no design changes are needed with respect to the Tefzel seating material. PEEK, Grafoil and Isolast were not affected by LIX{reg_sign}79 and MaxCalix within six months of exposure. The initial rapid weight gain observed in every polymer is assigned to the finite and

  13. Angular Study of the III Type Solar Bursts by Ukrainian Decameter Heliograph of UTR-2

    Science.gov (United States)

    Koval, Artem; Stanislavsky, Aleksander; Konovalenko, Aleksander

    2014-05-01

    Solar radio bursts are attractive manifestations of solar activity. They contain useful information about physical processes in solar corona. The type III radio bursts are the most frequent events among many different types of solar bursts studied since middle of the last century. The type III bursts are generated by beams of fast electrons (beams velocity ~ 0.3c) ejected into the corona and propagated through coronal plasma to interplanetary medium. It is assumed that such an electron beam passing coronal plasma generates plasma waves that converse to electromagnetic waves registered as type III radio bursts. They are observed in a wide frequency range from 1 GHz to tens kHz. In particular, the decameter emission (10-30 MHz) of III type bursts arises at heights about 2-3 solar radii from the center of the Sun. In the last decades the various ground-based, satellite and spacecraft observations have provided detailed information about features of the bursts. Due to non-thermal emission mechanism their intensity can be very high that allows ones to record the bursts even by amateur radio astronomers with help of elementary antennas (for example, half-wave dipole) and simple radio equipment. At dynamic spectra the type III radio bursts are characterized by very fast frequency drifts. Usually, the analysis of such two-dimensional spectrograms reveals also duration and intensity of the events in time and frequency; if the antenna facilities permit, as well as degree of polarization. It should be noticed that the observations of angular three-dimensional structure of the burst source are also of great interest. Our knowledge about angular structure of type III radio bursts in decameter wavelengths was very restricted because of the absence of appropriate radio astronomy instruments. Recently, the difficulty has been overcome by means of the UTR-2 radio telescope (Kharkiv, Ukraine) in heliographic modes. It was successfully used for heliographic observations of solar

  14. Conglutinin exhibits a complement-dependent enhancement of the respiratory burst of phagocytes stimulated by E. coli

    DEFF Research Database (Denmark)

    Friis, P; Svehag, S E; Andersen, Ove

    1991-01-01

    . Conglutinin enhances, in a dose-dependent manner, the respiratory burst of spleen cells stimulated with serum-opsonized Escherichia coli. The enhancement was only demonstrable in the presence of a functional complement system. The conglutinin-mediated enhancement of the respiratory burst was inhibited......Conglutinin is a mammalian C-type lectin which shows anti-bacterial activity when tested in vivo and in vitro. This study concerns the effect of conglutinin on the respiratory burst of murine spleen cells, using a chemiluminescence assay for measurement of generated reactive oxygen metabolites...

  15. Investigating the Conditions of the Formation of a Type II Radio Burst on 2014 January 8

    Science.gov (United States)

    Su, W.; Cheng, X.; Ding, M. D.; Chen, P. F.; Ning, Z. J.; Ji, H. S.

    2016-10-01

    It is believed that type II radio bursts are generated by shock waves. In order to understand the generation conditions of type II radio bursts, we analyze the physical parameters of a shock front. The type II radio burst we selected was observed by the Siberian Solar Radio Telescope (SSRT) and Learmonth radio station and was associated with a limb coronal mass ejection (CME) occurring on 2014 January 8 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The evolution of the CME in the inner corona presents a double-layered structure that propagates outward. We fit the outer layer (OL) of the structure with a partial circle and divide it into seven directions from ‑45° to 45° with an angular separation of 15°. We measure the OL speed along the seven directions and find that the speed in the direction of ‑15° with respect to the central direction is the fastest. We use the differential emission measure method to calculate the physical parameters at the OL at the moment when the type II radio burst was initiated, including the temperature (T), emission measure (EM), temperature ratio ({T}d/{T}{{u}}), compression ratio (X), and Alfvén Mach number (M A). We compare the quantities X and M A to those obtained from band-splitting in the radio spectrum, and find that this type II radio burst is generated at a small region of the OL that is located at the sector in the 45° direction. The results suggest that the generation of type II radio bursts (shocks) requires larger values of X and M A rather than simply a higher speed of the disturbance.

  16. ASKAP Joins the Hunt for Mysterious Bursts

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    A new telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), has joined the search for energetic and elusive fast radio bursts. And in just a few days of looking, its already had success!Elusive TransientsThe Parkes radio telescope, which has detected all but five of the fast radio bursts published to date, has a very narrow field of view. [CSIRO]Fast radio bursts are mysterious millisecond-duration radio pulses that were first discovered around a decade ago. Since that time particularly in recent years weve made some progress toward the goal of localizing them. Were now fairly convinced that fast radio bursts come from outside of the galaxy, and yet theyre enormously bright orders of magnitude more luminous than any pulse seen from the Milky Way.Better identification of where these mysterious bursts come from would help us to determine what they are. But so far, weve discovered only around 30 such bursts, despite the fact that theyre estimated to occur at a rate of 3,000 events per day across the whole sky.Why are they so hard to find? Due to their short duration, effective detection would require instantaneous coverage of a very large fraction of the sky. The Parkes radio telescope which has detected all but five of the fast radio bursts published to date has a field of view spanning less than a square degree,significantly limiting our ability to rapidly survey for these transients.FRB 170107s band-averaged pulse (top) and dynamic spectrum (bottom). [Bannister et al. 2017]A New Array in TownA new player is now on the scene, however, and its already had huge success. ASKAP is a wide-field radio telescope made up of an array of 12-meter antennas. Using phased-array-feed technology, ASKAP is able to instantaneously observe an effective area of 160 square degrees an enormous field compared to Parkes 0.6 square degrees! This capability significantly increases our chances of being able to detect fast radio bursts.In a new study led by Keith Bannister

  17. Quantifying the Opportunity Space for Future Electricity Generation: An Application to Offshore Wind Energy in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Marcy, Cara [National Renewable Energy Lab. (NREL), Golden, CO (United States); Beiter, Philipp [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-09-01

    This report provides a high-level indicator of the future electricity demand for additional electric power generation that is not met by existing generation sources between 2015 and 2050. The indicator is applied to coastal regions, including the Great Lakes, to assess the regional opportunity space for offshore wind. An assessment of opportunity space can be a first step in determining the prospects and the system value of a technology. The metric provides the maximal amount of additional generation that is likely required to satisfy load in future years.

  18. Method and apparatus for coherent burst ranging

    Science.gov (United States)

    Wachter, E.A.; Fisher, W.G.

    1998-04-28

    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time. 12 figs.

  19. Efficient inhibition of bursts by bursts in the auditory system of crickets.

    Science.gov (United States)

    Marsat, G; Pollack, G S

    2007-06-01

    In crickets, auditory information about ultrasound is carried bilaterally to the brain by the AN2 neurons. The ON1 neuron provides contralateral inhibitory input to AN2, thereby enhancing bilateral contrast between the left and right AN2s, an important cue for sound localization. We examine how the structures of the spike trains of these neurons affect this inhibitory interaction. As previously shown for AN2, ON1 responds to salient peaks in stimulus amplitude with bursts of spikes. Spike bursts, but not isolated spikes, reliably signal the occurrence of specific features of the stimulus. ON1 and AN2 burst at similar times relative to the amplitude envelope of the stimulus, and bursts are more tightly time-locked to stimulus feature than the isolated spikes. As a consequence, spikes that, in the absence of contralateral inhibition, would occur within AN2 bursts are more likely to be preceded by spikes in ON1 (mainly also in bursts) than are isolated AN2 spikes. This leads to a large decrease in the burst rate of the inhibited AN2. We conclude that the match in coding properties of ON1 and AN2 allows contralateral inhibition to be most efficient for those portions of the response that carry the behaviourally relevant information, i.e. for bursts.

  20. Nutrient generation at dairies and feedlots in the United States Pacific Northwest for 2002 summarized for NHDPlus v2 catchments

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of nitrogen and phosphorus generated by cattle at dairies and feedlots...

  1. Long-term outbreak of Klebsiella pneumoniae& third generation cephalosporin use in a neonatal intensive care unit in north India

    Directory of Open Access Journals (Sweden)

    Tuhina Banerjee

    2016-01-01

    Interpretation & conclusions: The study indicates that empirical use of third generation cephalosporins may promote the emergence, persistence, and dissemination of resistant isolates in the hospital environment. Periodic review of antibiotic policy is necessary for rationalized use of antibiotics.

  2. Application of phosphorus generated by non-cattle livestock to pasture land in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of phosphorus generated by pastured, non-cattle livestock that was...

  3. Application of nitrogen generated by non-cattle livestock to pasture land in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of nitrogen generated by pastured, non-cattle livestock that was...

  4. Application of nitrogen generated by grazing cattle to range land in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of nitrogen generated by grazing cattle that was applied to range land...

  5. Application of phosphorus generated by grazing cattle to range land in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of phosphorus generated by grazing cattle that was applied to range...

  6. A new burst assembly technique for supporting QoS in optical burst switching networks

    Institute of Scientific and Technical Information of China (English)

    Xiaolong Yang(阳小龙); Mingrui Dang(党明瑞); Youju Mao(毛幼菊); Lemin Li(李乐民)

    2003-01-01

    This letter proposes a new burst assembly technique for supporting QoS in optical burst switching (OBS)networks. It consists of the adaptive-threshold burst assembly mechanism and QoS-based random offset-time scheme. The assembly mechanism, which is fit well to multi-class burst assembly, not only matcheswith IP QoS mechanism based on packet classification, and also utilizes fairly and efficiently assemblycapacity. Based on token-bucket model and burst segment selective discard (BSSD), the offset-time schemecan smooth the traffic to support OBS QoS. The simulation results show that the technique can improvethe performance in terms of packet loss probability (PLP).

  7. An Intelligent Segmented Burst Assembly Mechanism in Optical Burst Switching Networks

    Institute of Scientific and Technical Information of China (English)

    XIE Yi-Yuan; ZHANG Jian-Guo

    2008-01-01

    We focus on the burst assembly mechanism and propose a new intelligent method in which the burst is assembled from several internet protocol (IP) packets in which the number of IP packets is changed according to the traffic load and the burst is segmented into several parts, called the ISOBS mechanism. The average burst assembly time of the ISOBS mechanism decreases as compared with the fixed-assembly-time and fixed-assembly-time-and-length mechanisms. The loss ratio decreases 50% as compared with the general optical burst switching (OBS) mechanism. The last segment can carry high quality of service (QOS) information. We can achieve that the loss ratio of the last segment is almost zero when the traffic load is less than 0.05. When the traffic load is 0.9, the loss ratio of the last segment is 0.0041. The ISOBS can support to transmit different QOS data.

  8. In vitro reinforcement of hippocampal bursting: a search for Skinner's atoms of behavior.

    OpenAIRE

    Stein, L; Xue, B G; Belluzzi, J D

    1994-01-01

    A novel "in vitro reinforcement" paradigm was used to investigate Skinner's (1953) hypotheses (a) that operant behavior is made up of infinitesimal "response elements" or "behavioral atoms" and (b) that these very small units, and not whole responses, are the functional units of reinforcement. Our tests are based on the assumption that behavioral atoms may plausibly be represented at the neural level by individual cellular responses. As a first approach, we attempted to reinforce the bursting...

  9. Intelligent Distributed Generation and Storage Units for DC Microgrids - A New Concept on Cooperative Control without Communications Beyond Droop Control

    DEFF Research Database (Denmark)

    Aldana, Nelson Leonardo Diaz; Dragicevic, Tomislav; Vasquez, Juan Carlos;

    2014-01-01

    . Typically, voltage droop loops are used for interconnecting several different units in parallel to a microgrid. This paper proposes a new decentralized strategy based on fuzzy logic that ensures stored energy balance, for a low voltage DC microgrid with distributed battery energy storage systems...

  10. 75 FR 53985 - Arizona Public Service Company, et al., Palo Verde Nuclear Generating Station, Unit 3; Temporary...

    Science.gov (United States)

    2010-09-02

    ..., core physics, and neutronic capability of the NGF LFAs in the PVNGS, Unit 3 reactor core. The thermal...-coolant accident (LOCA) and non-LOCA criteria, mechanical design, thermal hydraulic, seismic, core physics..., which the licensee commits to being due October 30, 2010, shall include thermal hydraulic...

  11. Powerplant Productivity Improvement Study: historic performance of Illinois investor-owned electrical-generating units. Final report, Project 2, Task 1

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-05-04

    In this task the historical performance of powerplants in Illinois was examined and the opportunities for improved powerplant productivity in Illinois was determined. The four utilities considered were the major investor-owned electric generating utilities in Illinois, i.e., Central Illinois Light Co., (CILCO), Central Illinois Public Service (CIPS), Commonwealth Edison (CECO), and Illinois Power (IP). The major findings are: (1) for evaluation purposes, the equivalent availability was judged to be the most-appropriate measure; (2) in terms of powerplant productivity, IP is among the best in the nation and, in terms of productivity from large coal units, it ranks in the top five nationally; (3) in general, the performance of coal-fired units of CILCO and CECO have been below national averages and in some cases, significantly below; (4) a review of the trends in production of all Illinois units reveals that Illinois units as a group have been generally below national averages for the respective unit classes; (5) as noted in this and other studies, productivities of the nuclear plants in Illinois have been below the national average for all comparable nuclear plants; and (6) this analysis should be updated when national 1977 and 1978 Edison Electric Institute data become publicly available.

  12. Effect of the air outlet louver on the noise generated by the outdoor set of a split-unit air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Junwei; Ding, Guoliang [Department of Power and Energy Engineering, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030 (China)

    2006-10-15

    In order to analyze the influence of the air outlet louver on the noise generated by the outdoor set of a split-unit air conditioner, the flow field in the outdoor set is simulated with the CFD software STAR-CD. The relative turbulent intensities are computed and the influence of the shape and the steel wire diameter of the air outlet louver on the noise generated by the outdoor set is analyzed. The results of computation and experiment show that the circular shape of air outlet louver gives benefit of noise decrease. An air outlet louver with different diameters of steel wires is designed on the basis of analysis of the influence of the steel wire diameter of the air outlet louver on the noise. The computation and experiment validate that the air outlet louver with different diameters of steel wires can improve the aerodynamic performance and reduce the noise generated by the outdoor set. (author)

  13. α-Calcium calmodulin kinase II modulates the temporal structure of hippocampal bursting patterns.

    Directory of Open Access Journals (Sweden)

    Jeiwon Cho

    Full Text Available The alpha calcium calmodulin kinase II (α-CaMKII is known to play a key role in CA1/CA3 synaptic plasticity, hippocampal place cell stability and spatial learning. Additionally, there is evidence from hippocampal electrophysiological slice studies that this kinase has a role in regulating ion channels that control neuronal excitability. Here, we report in vivo single unit studies, with α-CaMKII mutant mice, in which threonine 305 was replaced with an aspartate (α-CaMKII(T305D mutants, that indicate that this kinase modulates spike patterns in hippocampal pyramidal neurons. Previous studies showed that α-CaMKII(T305D mutants have abnormalities in both hippocampal LTP and hippocampal-dependent learning. We found that besides decreased place cell stability, which could be caused by their LTP impairments, the hippocampal CA1 spike patterns of α-CaMKII(T305D mutants were profoundly abnormal. Although overall firing rate, and overall burst frequency were not significantly altered in these mutants, inter-burst intervals, mean number of intra-burst spikes, ratio of intra-burst spikes to total spikes, and mean intra-burst intervals were significantly altered. In particular, the intra burst intervals of place cells in α-CaMKII(T305D mutants showed higher variability than controls. These results provide in vivo evidence that besides its well-known function in synaptic plasticity, α-CaMKII, and in particular its inhibitory phosphorylation at threonine 305, also have a role in shaping the temporal structure of hippocampal burst patterns. These results suggest that some of the molecular processes involved in acquiring information may also shape the patterns used to encode this information.

  14. Ground shock from multiple earth penetrator bursts: Effects for hexagonal weapon arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kmetyk, L.N.; Yarrington, P.

    1990-08-01

    Calculations have been performed with the HULL hydrocode to study ground shock effects for multiple earth penetrator weapon (EPW) bursts in hexagonal-close-packed (HCP) arrays. Several different calculational approaches were used to treat this problem. The first simulations involved two-dimensional (2D) calculations, where the hexagonal cross-section of a unit-cell in an effectively-infinite HCP array was approximated by an inscribed cylinder. Those calculations showed substantial ground shock enhancement below the center of the array. To refine the analysis, 3D unit-cell calculations were done where the actual hexagonal cross-section of the HCP array was modelled. Results of those calculations also suggested that the multiburst array would enhance ground shock effects over those for a single burst of comparable yield. Finally, 3D calculations were run in which an HCP array of seven bursts was modelled explicitly. In addition, the effects of non-simultaneity were investigated. Results of the seven-burst HCP array calculations were consistent with the unit-cell results and, in addition, provided information on the 3D lethal contour produced by such an array.

  15. Bursting synchronization in clustered neuronal networks

    Institute of Scientific and Technical Information of China (English)

    Yu Hai-Tao; Wang Jiang; Deng Bin; Wei Xi-Le

    2013-01-01

    Neuronal networks in the brain exhibit the modular (clustered) property,i.e.,they are composed of certain subnetworks with differential internal and external connectivity.We investigate bursting synchronization in a clustered neuronal network.A transition to mutual-phase synchronization takes place on the bursting time scale of coupled neurons,while on the spiking time scale,they behave asynchronously.This synchronization transition can be induced by the variations of inter-and intracoupling strengths,as well as the probability of random links between different subnetworks.Considering that some pathological conditions are related with the synchronization of bursting neurons in the brain,we analyze the control of bursting synchronization by using a time-periodic external signal in the clustered neuronal network.Simulation results show a frequency locking tongue in the driving parameter plane,where bursting synchronization is maintained,even in the presence of external driving.Hence,effective synchronization suppression can be realized with the driving parameters outside the frequency locking region.

  16. Diagnostics From Three Rising Submillimeter Bursts

    CERN Document Server

    Zhou, Ai-Hua; Wang, Xin-Dong

    2015-01-01

    In the paper we investigate three novel rising submillimeter (THz) bursts occurred sequentially in a super-Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu/GHz (corresponding spectral index $\\alpha$ of 1.6) for the THz spectral components of 2003 October 28 and November 4 bursts, while it can attain values of 235 sfu/GHz ($\\alpha$=4.8) for 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of high relativistic electrons with a low-energy cutoff of 1 MeV , while it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than that in microwave (MW) one. It is interesting that the THz source radius decreased by 20--50$\\%$ during the decay phase for the three events, but the MW one increased by 28$\\%$ for the 2003 Novemb...

  17. Olivary subthreshold oscillations and burst activity revisited

    Directory of Open Access Journals (Sweden)

    Paolo eBazzigaluppi

    2012-11-01

    Full Text Available The inferior olive forms one of the major gateways for information that travels to the cerebellar cortex. Olivary neurons process sensory and motor signals that are subsequently relayed to Purkinje cells. The intrinsic subthreshold membrane potential oscillations of the olivary neurons are thought to be important for gating this flow of information. In vitro studies have revealed that the phase of the subthreshold oscillation determines the size of the olivary burst and may gate the information flow or encode the temporal state of the olivary network. Here, we investigated whether the same phenomenon occurred in murine olivary cells in an intact olivocerebellar system using the in vivo whole-cell recording technique. Our in vivo findings revealed that the number of wavelets within the olivary burst did not encode the timing of the spike relative to the phase of the oscillation but was related to the amplitude of the oscillation. Manipulating the oscillation amplitude by applying Harmaline confirmed the inverse relationship between the amplitude of oscillation and the number of wavelets within the olivary burst. Furthermore, we demonstrated that electrotonic coupling between olivary neurons affect this modulation of the olivary burst size. Based on these results, we suggest that the olivary burst size might reflect the expectancy of a spike to occur rather than the spike timing, and that this process requires the presence of gap junction coupling.

  18. The Cosmic Gamma-Ray Bursts

    CERN Document Server

    Djorgovski, S G; Kulkarni, S R; Sari, R; Bloom, J S; Galama, T J; Harrison, F A; Price, P A; Fox, D; Reichart, D; Yost, S; Berger, E; Diercks, A H; Goodrich, R; Chaffee, F H

    2001-01-01

    Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean gamma-ray energies after the beaming corrections are ~ 10^51 erg. Bursts are associated with faint ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host gal...

  19. Meteor burst in the post 2000 era

    Science.gov (United States)

    Marriott, C.; Oduol, V.; Ghosh, A.; Tailor, B.

    In recent years a renewed interest has been shown in the possibility of using meteor burst links in tactical communications, both for networking and covert operations. Some of the applications that recent performance improvements would permit are evaluated. In evaluating the feasibility of a meteor burst implementation, certain technical and physical limitations are addressed. For the success of these applications, interoperability with other communication systems is necessary. The level of interoperability with other media, and the standards necessary to assure this interoperability are examined. Methods of minimizing and combating jamming are proposed. Meteor burst systems can be used in a large number of applications within a tactical environment. The principal disadvantage of the meteor burst medium is the problem of interference to other spectrum users from the probe end, and the interference from other users at the receiver end. The low throughput characteristic of meteor burst compares with some of the channel capacities used in other systems. Interoperability with other networks or communications links is relatively easy if certain straightforward protocols and standards are established.

  20. GRB Catalog: Bursts from Vela to Swift

    Science.gov (United States)

    Angelini, L.

    2008-01-01

    Gamma ray burst (GRB) astronomy started when the first event was recorded on July 2, 1967 by Vela 4a and 4b. Since then many missions have flown experiments capable of detecting GRBs. The events collected by these older experiments are mostly available in paper copy, each containing a few ten to a few hundred bursts. No systematic effort in cataloging of these bursts has been available. In some cases the information is unpublished and in others difficult to retrieve. The first major GRB catalog was obtained by GRO with the BATSE experiment. It contains more than 2000 bursts and includes homogeneous information for each of the bursts. With the launch of Swift, the first Gamma-ray/X-ray mission dedicated to the study of GRBs and their afterglows, a wealth of information is collected by the Swift instrument as well as from ground-based telescopes. This talk will describe the efforts to create a comprehensive GRBCAT and its current status and future prospective.

  1. Fast Plasma Investigation for MMS: Simulation of the Burst Triggering System

    Science.gov (United States)

    Barrie, A. C.; Dorelli, J. C.; Winkert, G. E.; Lobell, J. V.; Holland, M. P.; Adrian, M. L.; Pollock, C. J.

    2011-01-01

    The Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 degree x 180 degree fields-of-view (FOV) are set 90 degrees apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 degree x 180 degree fan about the its nominal viewing (0 deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb (raised dot) per second of electron data while the DIS generates 1.1-Mb (raised dot) per second of ion data yielding an FPI total data rate of 6.6-Mb (raised dot) per second. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. This requires a data ranking process known as the burst trigger system. The burst trigger system uses pseudo physical quantities to approximate the local plasma environments. As each pseudo quantity will have a different value, a set of two scaling factors is employed for each pseudo term. These pseudo

  2. Fast Plasma Investigation for MMS: Simulation of the Burst Triggering System

    Science.gov (United States)

    Barrie, A.; Dorelli, J.; Adrian, M. L.; Paterson, W. R.; Pollock, C. J.

    2011-12-01

    The Magnetospheric MultiScale (MMS) mission will enable the study of small-scale magnetic reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors, eight (8) identical half top-hat ion sensors, and an Instrument Data Processing Unit (IDPU) on each of the four (4) MMS spacecraft. The sensors are packaged into pairs (DES & DIS) whose 90° x 180° (with electostatic deflection) fields-of-view (FOV) are placed at 90° intervals around the spacecraft periphery. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° x 180° fan about the its nominal viewing (0° deflection) direction. The combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30ms (electrons) and 150ms (ions), respectively. To probe the diffusion regions of reconnection events, the highest temporal/spatial resolution mode of FPI results in the DES complement of each spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 7.6-Mb s-1 for each of the 4 MMS spacecraft. The FPI electron and ion data is collected by the IDPU and transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Owing to limitations in downlink band width, only data sequences that contain the greatest potential for reconnection science may be down-linked by the spacecraft. This requires a data ranking process implemented as part of a burst trigger system. The FPI burst trigger system uses count rate sums representing pseudo physical quantities to approximate the local plasma environments. As each pseudo quantity will have a different value, a set of two scaling factors is employed for each pseudo term

  3. Impact of Dendritic Size and Dendritic Topology on Burst Firing in Pyramidal Cells

    NARCIS (Netherlands)

    van Elburg, Ronald A. J.; van Ooyen, Arjen

    2010-01-01

    Neurons display a wide range of intrinsic firing patterns. A particularly relevant pattern for neuronal signaling and synaptic plasticity is burst firing, the generation of clusters of action potentials with short interspike intervals. Besides ion-channel composition, dendritic morphology appears to

  4. EDGE: explorer of diffuse emission and gamma-ray burst explosions

    NARCIS (Netherlands)

    den Herder, J.W.; Piro, L.; Ohashi, T.; Amati, L.; Atteia, J.; Barthelmy, S.D.; Barbera, M.; Barret, D.; Basso, S.; de Boer, M.; Borgani, S.; Boyarskiy, O.; Branchini, E.; Branduardi-Raymont, G.; Briggs, M.; Brunetti, G.; Budtz-Jorgensenf, C.; Burrows, D.N.; Campana, S.; Caroli, E.; Chincarini, G.; Christensen, F.; Cocchi, M.; Comastri, A.; Corsi, A.; Cotroneo, V.; Conconi, P.; Colasanti, L.; Cusamano, G.; Rosa, A.; Del Santo, M.; Ettori, S.; Ezoe, Y.; Ferrari, L.; Feroci, M.; Finger, M.; Fishman, G.; Fujimoto, R.; Galeazzi, M.; Galli, A.; Gatti, F.; Gehrels, N.; Gendre, B.; Ghirlanda, G.; Ghisellini, G.; Giommi, P.; Girardi, M.; Guzzo, L.; Haardt, F.; Hepburn, I.; Hermsen, W.; Hoevers, H.; Holland, A.; in 't Zand, J.J.M.; Ishisaki, Y.; Kawahara, H.; Kawai, N.; Kaastra, J.; Kippen, M.; de Korte, P.A.J.; Kouveliotou, C.; Kusenko, A.; Labanti, C.; Lieu, R.; Macculi, C.; Makishima, K.; Matt, G.; Mazotta, P.; McCammon, D.; Méndez, M.; Mineo, T.; Mitchell, S.; Mitsuda, K.; Molendi, S.; Moscardini, L.; Mushotzky, R.; Natalucci, L.; Nicastro, F.; O'Brien, P.; Osborne, J.; Paerels, F.; Page, M.; Paltani, S.; Pareschi, G.; Perinati, E.; Perola, C.; Ponman, T.; Rasmussen, A.; Roncarelli, M.; Rosati, P.; Ruchayskiy, O.; Quadrini, E.; Sakurai, I.; Salvaterra, R.; Sasaki, S.; Wijers, R.; et al., [Unknown

    2007-01-01

    How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysics. EDGE will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions, through the period of galaxy cl

  5. Bursting and large-scale intermittency in turbulent convection with differential rotation

    DEFF Research Database (Denmark)

    Garcia, O.E.; Bian, N.H.

    2003-01-01

    The tilting mechanism, which generates differential rotation in two-dimensional turbulent convection, is shown to produce relaxation oscillations in the mean flow energy integral and bursts in the global fluctuation level, akin to Lotka-Volterra oscillations. The basic reason for such behavior...

  6. Generating units in operation. National electrical system (Public service) 2002; Unidades generadoras en operacion. Sistema electrico nacional (Servicio publico) 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-03-15

    The information regarding the generation effective capacity updated to December 31, 2002 is presented. A detailed description of the effective capacity by generation region, control area, generation type and federal entity is presented. Also graphs are shown with the energy balance of the National Electrical System of Comision Federal de Electricidad and Luz y Fuerza del Centro. [Spanish] Se presenta la informacion relativa a la capacidad efectiva de generacion actualizada al 31 de diciembre de 2002. Se hace una descripcion detallada de la capacidad efectiva por region de generacion, por area de control, por tipo de generacion y por entidad federativa. Tambien se presentan unas graficas con el balance de energia del Sistema Electrico Nacional de la Comision Federal de Electricidad y de Luz y Fuerza del Centro.

  7. Decentralized Voltage Control Coordination of On-Load Tap Changer Transformers, Distributed Generation Units and Flexible Loads

    DEFF Research Database (Denmark)

    Romani Dalmau, Aina; Martinez Perez, David; Diaz de Cerio Mendaza, Iker

    2015-01-01

    . Under low penetration levels, several voltage regulation elements have been efficiently employed up to now. However, under large distributed generation levels, the traditional techniques have to be coordinated with new upcoming solutions, such us demand response. In this paper a simple and decentralized......The increase of distributed generation is expected to generate instabilities, such as power imbalances or voltage deviations in the power system. At the distribution level, maintaining the bus voltages within the stipulated limits is one of the major challenges for the distribution system operator...... approach is introduced in order to coordinate the voltage control capability from different assets in medium voltage networks. In this sense, the on-load tap changer strategy of the primary substation and the power factor control of wind turbines and combined heat and power plants are combined...

  8. The Impact of a Supernova Remnant on Fast Radio Bursts

    CERN Document Server

    Piro, Anthony L

    2016-01-01

    Fast radio bursts (FRBs) are millisecond bursts of radio radiation that appear to come from cosmological distances. Although their progenitors remain mysterious, the timescales and energetics of the events have lead to many theories associating FRBs with young neutron stars. Motivated by this, I explore the interaction of FRBs with young supernova remnants (SNRs), and I discuss the potential observational consequences and constraints of such a scenario. As the SN ejecta plows into the interstellar medium (ISM), a reverse shock is generated that passes back through the material and ionizes it. This leads to a dispersion measure (DM) associated with the SNR as well as a time derivative for DM. Times when DM is high are generally overshadowed by free-free absorption, which, depending on the mass of the ejecta and the density of the ISM, may be probed at frequencies of $400\\,{\\rm MHz}$ to $1.4\\,{\\rm GHz}$ on timescales of $\\sim100-500\\,{\\rm yrs}$ after the SN. Magnetic fields generated at the reverse shock may be...

  9. Rotational IMRT delivery using a digital linear accelerator in very high dose rate 'burst mode'

    Science.gov (United States)

    Salter, Bill J.; Sarkar, Vikren; Wang, Brian; Shukla, Himanshu; Szegedi, Martin; Rassiah-Szegedi, Prema

    2011-04-01

    Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units per minute (MU min-1) high dose rate bursts of dose are facilitated by a flattening-filter-free treatment beam on a Siemens Artiste (Oncology Care Systems, Siemens Medical Solutions, Concord, CA, USA) digital linear accelerator in a non-clinical configuration. Burst mode delivery differs from continuous mode delivery, used by Elekta's VMAT (Elekta Ltd, Crawley, UK) and Varian's RapidArc (Varian Medical Systems, Palo Alto, CA, USA) implementations, in that dose is not delivered while MLC leaves are moving. Instead, dose is delivered in bursts over very short arc angles and only after an MLC segment shape has been completely formed and verified by the controller. The new system was confirmed to be capable of delivering a wide array of clinically relevant treatment plans, without machine fault or other delivery anomalies. Dosimetric accuracy of the modulated arc platform, as well as the Prowess (Prowess Inc., Concord, CA, USA) prototype treatment planning version utilized here, was quantified and confirmed, and delivery times were measured as significantly brief, even with large hypofractionated doses. The burst mode modulated arc approach evaluated here appears to represent a capable, accurate and efficient delivery approach.

  10. X-ray bursts observed with JEM-X

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Chenevez, Jérôme; Lund, Niels;

    2006-01-01

    We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found.......We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found....

  11. A mechanism for fast radio bursts

    CERN Document Server

    Romero, Gustavo E; Vieyro, Florencia L

    2015-01-01

    Fast radio bursts are mysterious transient sources likely located at cosmological distances. The derived brightness temperatures exceed by many orders of magnitude the self-absorption limit of incoherent synchrotron radiation, implying the operation of a coherent emission process. We propose a radiation mechanism for fast radio bursts where the emission arises from collisionless Bremsstrahlung in strong plasma turbulence excited by relativistic electron beams. We discuss possible astrophysical scenarios in which this process might operate. The emitting region is a turbulent plasma hit by a relativistic jet, where Langmuir plasma waves produce a concentration of intense electrostatic soliton-like regions (cavitons). The resulting radiation is coherent and, under some physical conditions, can be polarised and have a power-law distribution in energy. We obtain radio luminosities in agreement with the inferred values for fast radio bursts. The timescale of the radio flare in some cases can be extremely fast, of t...

  12. Study on fault induced rock bursts

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-hua; DOU Lin-ming; LU Cai-ping; MU Zong-long; CAO An-ye

    2008-01-01

    In order to study the rules of rock bursts caused by faults by means of mechanical analysis of a roof rock-mass balanced structure and numerical simulation about fault slip destabilization, the effect of coal mining operation on fault plane stresses and slip displacement were studied. The results indicate that the slip displacement sharply increases due to the decrease of normal stress and the increase of shear stress at the fault plane when the working face advances from the footwall to the fault itself, which may induce a fault rock burst. However, this slip displacement will be very small due to the increase of normal stress and the decrease of shear stress when the working face advances from the hanging wall to the fault itself, which results in a very small risk of a fault rock burst.

  13. On the bursting of gene products

    CERN Document Server

    Yvinec, Romain

    2011-01-01

    In this article we demonstrate that the so-called bursting production of molecular species during gene expression may be an artifact caused by low time resolution in experimental data collection and not an actual burst in production. We reach this conclusion through an analysis of a two-stage and binary model for gene expression, and demonstrate that in the limit when mRNA degradation is much faster than protein degradation they are equivalent. The negative binomial distribution is shown to be a limiting case of the binary model for fast "on to off" state transitions and high values of the ratio between protein synthesis and degradation rates. The gene products population increases by unity but multiple times in a time interval orders of magnitude smaller than protein half-life or the precision of the experimental apparatus employed in its detection. This rare-and-fast one-by-one protein synthesis has been interpreted as bursting.

  14. Variable protostellar accretion with episodic bursts

    CERN Document Server

    Vorobyov, Eduard I

    2015-01-01

    We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model with improved disk thermal balance and star-disk interaction, we computed the evolution of protostellar disks formed from the gravitational collapse of prestellar cores. In agreement with our previous studies, we find that cores of higher initial mass and angular momentum produce disks that are more favorable to gravitational instability and fragmentation, while a higher background irradiation and magnetic fields moderate the disk tendency to fragment. The protostellar accretion in our models is time-variable, thanks to the nonlinear interaction between different spiral modes in the gravitationally unstable disk, and can undergo episodic bursts when fragments migrate onto the star owing to the gravitational interaction with other fragments or spiral arms. Most bursts occur...

  15. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra

    2016-01-01

    Full Text Available Gamma-ray bursts (GRBs are extremely energetic events at cosmological distances. They provide unique laboratory to investigate fundamental physical processes under extreme conditions. Due to extreme luminosities, GRBs are detectable at very high redshifts and potential tracers of cosmic star formation rate at early epoch. While the launch of Swift and Fermi has increased our understanding of GRBs tremendously, many new questions have opened up. Radio observations of GRBs uniquely probe the energetics and environments of the explosion. However, currently only 30% of the bursts are detected in radio bands. Radio observations with upcoming sensitive telescopes will potentially increase the sample size significantly and allow one to follow the individual bursts for a much longer duration and be able to answer some of the important issues related to true calorimetry, reverse shock emission, and environments around the massive stars exploding as GRBs in the early Universe.

  16. Bursting activity spreading through asymmetric interactions

    CERN Document Server

    Onaga, Tomokatsu

    2014-01-01

    People communicate with those who have the same background or share a common interest by using a social networking service (SNS). News or messages propagate through inhomogeneous connections in an SNS by sharing or facilitating additional comments. Such human activity is known to lead to endogenous bursting in the rate of message occurrences. We analyze a multi-dimensional self-exciting process to reveal dependence of the bursting activity on the topology of connections and the distribution of interaction strength on the connections. We determine the critical conditions for the cases where interaction strength is regulated at either the point of input or output for each person. In the input regulation condition, the network may exhibit bursting with infinitesimal interaction strength, if the dispersion of the degrees diverges as in the scale-free networks. In contrast, in the output regulation condition, the critical value of interaction strength, represented by the average number of events added by a single ...

  17. The ocean response to operational westerly wind bursts during the 1991 - 1992 El Nino

    Science.gov (United States)

    Kindle, John C.; Phoebus, Patricia A.

    1995-01-01

    Numerical simulations of the remotely forced ocean response to westerly wind bursts prior to and during the 1991 - 1992 El Nino are examined; the models are forced by wind stress from the U.S. Navy's atmospheric global operational analysis/forecast system. The study focuses on (1) the relative response of the first and second internal modes to a single episode of westerly bursts; (2) the role of westerly bursts in producing the eastern Pacific sea level variations from October 1990 to February 1992; and (3) the relative importance of the remotely forced sea level responses generated by central and western Pacific wind anomalies. The simulation use the Naval Research Laboratory global multilayer formulation; the suite of experiments includes hydrodynamic simulations that use both one- and three- active-layer reduced gravity models as well as an experiment that also includes thermodynamic effects. The models are executed from January 1, 1990, to March 1, 1992, a period that includes 10 significant westerly wind bursts or burst clusters and the 1991 - 1992 El Nino event. The numerical experiments reveal an ability to accurately simulate the eastern Pacific sea level variations during this period. In response to a single burst, the three-layer hydrodynamic simulation reveals that the second internal mode Kelvin wave yields a sea level change at the eastern boundary that is approximately one third that of the first mode and a surface velocity signature that is equivalent to the first mode. During the onset of the El Nino event the inclusion of higher modes also produces a more realistic representation of the observed eastern boundary sea level signal. Furthermore, by comparing the model response to particular wind bursts with the observed sea level at Baltra, Galapagos, a value of 2.5 - 2.6 m/s is suggested as the most appropriate mean speed for the first internal mode Kelvin wave during the onset phase. A scenario for the onset of the 1991 - 1992 El Nino is given.

  18. A compact terahertz burst emission system driven with 1 μm fiber laser

    Science.gov (United States)

    Adamonis, Juozas; Rusteika, Nerijus; Danilevičius, Rokas; Krotkus, Arūnas

    2013-04-01

    In this work we propose a compact, easily tunable terahertz burst generation system based on the mixing of two linearly chirped optical pulses in the Michelson interferometer. The use of linearly chirped optical pulses ejected straight from the fiber laser enabled us to avoid bulky external optical pulse stretching schemes. Even for non-compensated third and higher order dispersion that is taking place in the optical fiber terahertz bursts of relatively narrow bandwidth of 55 GHz were registered. The system operation range determined from the power measurements reached 2 THz.

  19. Synthesis of Variable Harmonic Impedance in Inverter-Interfaced Distributed Generation Unit for Harmonic Damping Throughout a Distribution Network

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverters in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective harmonic load current feedforward loop ba...

  20. Synthesis of variable harmonic impedance in inverter-interfaced distributed generation unit for harmonic damping throughout a distribution network

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverter in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective load harmonic current feedforward loop bas...

  1. Spikes and bursts in two types of thalamic projection neurons differentially shape sleep patterns and auditory responses in a songbird.

    Science.gov (United States)

    Hahnloser, Richard H R; Wang, Claude Z-H; Nager, Aymeric; Naie, Katja

    2008-05-07

    In mammals, the thalamus plays important roles for cortical processing, such as relay of sensory information and induction of rhythmical firing during sleep. In neurons of the avian cerebrum, in analogy with cortical up and down states, complex patterns of regular-spiking and dense-bursting modes are frequently observed during sleep. However, the roles of thalamic inputs for shaping these firing modes are largely unknown. A suspected key player is the avian thalamic nucleus uvaeformis (Uva). Uva is innervated by polysensory input, receives indirect cerebral feedback via the midbrain, and projects to the cerebrum via two distinct pathways. Using pharmacological manipulation, electrical stimulation, and extracellular recordings of Uva projection neurons, we study the involvement of Uva in zebra finches for the generation of spontaneous activity and auditory responses in premotor area HVC (used as a proper name) and the downstream robust nucleus of the arcopallium (RA). In awake and sleeping birds, we find that single Uva spikes suppress and spike bursts enhance spontaneous and auditory-evoked bursts in HVC and RA neurons. Strong burst suppression is mediated mainly via tonically firing HVC-projecting Uva neurons, whereas a fast burst drive is mediated indirectly via Uva neurons projecting to the nucleus interface of the nidopallium. Our results reveal that cerebral sleep-burst epochs and arousal-related burst suppression are both shaped by sophisticated polysynaptic thalamic mechanisms.

  2. Gamma-Ray Burst Early Afterglows

    CERN Document Server

    Zhang, B

    2005-01-01

    The successful launch and operation of NASA's Swift Gamma-Ray Burst Explorer open a new era for the multi-wavelength study of the very early afterglow phase of gamma-ray bursts (GRBs). GRB early afterglow information is essential to explore the unknown physical composition of GRB jets, the link between the prompt gamma-ray emission and the afterglow emission, the GRB central engine activity, as well as the immediate GRB environment. Here I review some of the recent theoretical efforts to address these problems and describe how the latest Swift data give answers to these outstanding questions.

  3. Distribution of whistler mode bursts at Venus

    Science.gov (United States)

    Scarf, F. L.; Jordan, K. F.; Russell, C. T.

    1987-01-01

    Several thousand impulsive whistler mode noise bursts were detected by the Pioneer Venus wave instrument during the first 10 seasons with nightside traversals at low altitudes. The altitude distribution for these events shows that essentially all of the bursts were detected when the orbiter was less than 2000 km above the planet, suggesting that the varying plasma conditions could not maintain coherent whistler mode field-aligned guidance over greater distances. Within the 2000-km range, the distribution of the number of events versus altitude shows that there are two distinct subregions. These results are interpreted in terms of two types of whistler mode propagation from sources below the ionosphere.

  4. A Burst Chasing X-ray Polarimeter

    Science.gov (United States)

    Hill, Joanne

    2007-01-01

    This viewgraph presentation reviews the rationale, design, and importance of an X-Ray Polarimeter. There is a brief discussion of Gamma Ray Bursts, followed by a review of the theories of Gamma-Ray Bursts Polarization. This leads to the question of "How do we measure the polarization?" and a discussion of the GRB x-ray emission, the photoelectric effect and photoelectric polarimetry. The requirements for the work, can only be approached using a gas detector. This leads to a discussion of a Micropattern Gas Polarimeter, and the Time-Projection Chamber (TPC) X-ray Polarimeter.

  5. The Integral Burst Alert System (IBAS)

    CERN Document Server

    Mereghetti, S; Borkowski, J J; Walter, R; Pedersen, H

    2003-01-01

    We describe the INTEGRAL Burst Alert System (IBAS): the automatic software for the rapid distribution of the coordinates of the Gamma-Ray Bursts detected by INTEGRAL. IBAS is implemented as a ground based system, working on the near-real time telemetry stream. During the first six months of operations, six GRB have been detected in the field of view of the INTEGRAL instruments and localized by IBAS. Positions with an accuracy of a few arcminutes are currently distributed by IBAS to the community for follow-up observations within a few tens of seconds of the event.

  6. Supernovae and Gamma-Ray Bursts

    Science.gov (United States)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  7. First generation TREN dendrimers functionalized with naphthyl and/or dansyl units. Ground and excited state electronic interactions and protonation effects.

    Science.gov (United States)

    Passaniti, Paolo; Maestri, Mauro; Ceroni, Paola; Bergamini, Giacomo; Vögtle, Fritz; Fakhrnabavi, Hassan; Lukin, Oleg

    2007-04-01

    We report the photophysical properties (absorption and emission spectra, quantum yield, and lifetime) of five dendrimers of first generation based on a TREN (tris(2-aminoethyl)amine) skeleton functionalized at the periphery with naphthyl and/or 5-dimethylamino-1-naphthalenesulfonamide (hereafter called dansyl) chromophores. Each dendrimer comprises one tertiary amine unit in the core and three branches carrying a sulfonimido unit at the periphery, each one substituted by two identical or different moieties. In particular, TD6 and TN6 contain dansyl (D) or naphthyl (N) units, respectively, while TD3B3, TN3B3 and TN3D3 contain dansyl, naphthyl or benzyl (B) units at the periphery. The spectroscopic behaviour of these dendrimers has been investigated in acetonitrile solution and compared with that of reference compounds. For all dendrimers the absorption bands are red shifted compared to those of monomeric naphthyl and dansyl reference compounds. Moreover, the intense naphthyl and dansyl fluorescence is greatly quenched because of strong interactions between the two aromatic moieties linked by a sulfonimido unit. Protonation of the amine units of the dendrimers by addition of CF(3)SO(3)H (triflic) acid causes a decrease in intensity of the luminescence and a change in the shape of the emission bands. The shapes of the titration curves depend on the dendrimer, but in any case the effect of acid can be fully reversed by successive addition of base (tributylamine). The obtained results reveal that among the intradendrimer interactions the most important one is that taking place (via mesomeric interaction) between the various chromophores and a pair of sulfonimido groups.

  8. Phantom bursting is highly sensitive to noise and unlikely to account for slow bursting in beta-cells

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram

    2007-01-01

    Pancreatic beta-cells show bursting electrical activity with a wide range of burst periods ranging from a few seconds, often seen in isolated cells, over tens of seconds (medium bursting), usually observed in intact islets, to several minutes. The phantom burster model [Bertram, R., Previte, J...... and lowers the burst period dramatically in phantom bursters. It is therefore unlikely that slow bursting in single cells is driven by the slow phantom bursting mechanism, but could instead be driven by oscillations in glycolysis, which we show are stable to random ion channel fluctuations. Moreover, so...

  9. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    Energy Technology Data Exchange (ETDEWEB)

    Capozziello, S., E-mail: capozziello@na.infn.it [Dipartimento di Fisica, Universitá di Napoli “Federico II”, Via Cinthia, I-80126, Napoli (Italy); INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli (Italy); Gran Sasso Science Institute (INFN), Via F. Crispi 7, I-67100, L' Aquila (Italy); Lambiase, G. [Dipartimento di Fisica “E.R. Caianiello”, Universitá di Salerno, I-84084, Fisciano (Italy); INFN – Gruppo Collegato di Salerno (Italy)

    2015-11-12

    The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesic motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events. Possible applications to cosmology are discussed.

  10. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    Directory of Open Access Journals (Sweden)

    S. Capozziello

    2015-11-01

    Full Text Available The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesic motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events. Possible applications to cosmology are discussed.

  11. Fast mapping of terahertz bursting thresholds and characteristics at synchrotron light sources

    Directory of Open Access Journals (Sweden)

    Miriam Brosi

    2016-11-01

    Full Text Available Dedicated optics with extremely short electron bunches enable synchrotron light sources to generate intense coherent THz radiation. The high degree of spatial compression in this so-called low-α_{c} optics entails a complex longitudinal dynamics of the electron bunches, which can be probed studying the fluctuations in the emitted terahertz radiation caused by the microbunching instability (“bursting”. This article presents a “quasi-instantaneous” method for measuring the bursting characteristics by simultaneously collecting and evaluating the information from all bunches in a multibunch fill, reducing the measurement time from hours to seconds. This speed-up allows systematic studies of the bursting characteristics for various accelerator settings within a single fill of the machine, enabling a comprehensive comparison of the measured bursting thresholds with theoretical predictions by the bunched-beam theory. This paper introduces the method and presents first results obtained at the ANKA synchrotron radiation facility.

  12. AD 775 Pulse of Cosmogenic Radionuclides Production as Imprint of a Galactic Gamma-Ray Burst

    CERN Document Server

    Pavlov, A K; Konstantinov, A N; Ostryakov, V M; Vasilyev, G I; Vdovina, M A; Volkov, P A

    2013-01-01

    We suggest an explanation of a sharp increase in the abundance of cosmogenic radiocarbon found in tree rings dated AD 775. The increase could originate from high-energy irradiation of the atmosphere by a galactic gamma-ray burst. We argue that, unlike a cosmic ray event, a gamma-ray burst does not necessarily result in a substantial increase in long-lived 10Be atmospheric production. At the same time, the 36Cl nuclide would be generated in the amounts detectable in the corresponding ice core samples from Greenland and Antarctica. These peculiar features allow experimental discrimination of nuclide effects caused by gamma-ray bursts and by powerful proton events.

  13. Advanced waveforms and frequency with spinal cord stimulation: burst and high-frequency energy delivery.

    Science.gov (United States)

    Pope, Jason E; Falowski, Steven; Deer, Tim R

    2015-07-01

    In recent years, software development has been key to the next generation of neuromodulation devices. In this review, we will describe the new strategies for electrical waveform delivery for spinal cord stimulation. A systematic literature review was performed using bibliographic databases, limited to the English language and human data, between 2010 and 2014. The literature search yielded three articles on burst stimulation and four articles on high-frequency stimulation. High-frequency and burst stimulation may offer advantages over tonic stimulation, as data suggest improved patient tolerance, comparable increase in function and possible success with a subset of patients refractory to tonic spinal cord stimulation. High-frequency and burst stimulation are new ways to deliver energy to the spinal cord that may offer advantages over tonic stimulation. These may offer new salvage strategies to mitigate spinal cord stimulation failure and improve cost-effectiveness by reducing explant rate.

  14. INDUCED SCATTERING LIMITS ON FAST RADIO BURSTS FROM STELLAR CORONAE

    Energy Technology Data Exchange (ETDEWEB)

    Lyubarsky, Yuri [Physics Department, Ben-Gurion University, P.O.B. 653, Beer-Sheva 84105 (Israel); Ostrovska, Sofiya [Department of Mathematics, Atilim University, Incek 06836, Ankara (Turkey)

    2016-02-10

    The origin of fast radio bursts remains a puzzle. Suggestions have been made that they are produced within the Earth’s atmosphere, in stellar coronae, in other galaxies, or at cosmological distances. If they are extraterrestrial, the implied brightness temperature is very high, and therefore the induced scattering places constraints on possible models. In this paper, constraints are obtained on flares from coronae of nearby stars. It is shown that the radio pulses with the observed power could not be generated if the plasma density within and in the nearest vicinity of the source is as high as is necessary to provide the observed dispersion measure. However, one cannot exclude the possibility that the pulses are generated within a bubble with a very low density and pass through the dense plasma only in the outer corona.

  15. X-ray Burst Oscillations: From Flame Spreading to the Cooling Wake

    CERN Document Server

    Mahmoodifar, Simin

    2015-01-01

    Type I X-ray bursts are thermonuclear flashes observed from the surface of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but to date there haven't been any quantitative studies that consistently track the oscillation amplitude both during the rise and decay (tail) of bursts. Here we compute the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. We present results for two such "cooling wake" models, a "canonical" cooling model where each patch on the neutron star surface heats and cools identically, and an "asymmetric" model where parts of the star cool at different rates. We show that while canonical cooling models can generate oscillations in the tails of bursts, they cannot easily produce the highest observed modulation amplitudes. Alternative...

  16. Network burst dynamics under heterogeneous cholinergic modulation of neural firing properties and heterogeneous synaptic connectivity.

    Science.gov (United States)

    Knudstrup, Scott; Zochowski, Michal; Booth, Victoria

    2016-05-01

    The characteristics of neural network activity depend on intrinsic neural properties and synaptic connectivity in the network. In brain networks, both of these properties are critically affected by the type and levels of neuromodulators present. The expression of many of the most powerful neuromodulators, including acetylcholine (ACh), varies tonically and phasically with behavioural state, leading to dynamic, heterogeneous changes in intrinsic neural properties and synaptic connectivity properties. Namely, ACh significantly alters neural firing properties as measured by the phase response curve in a manner that has been shown to alter the propensity for network synchronization. The aim of this simulation study was to build an understanding of how heterogeneity in cholinergic modulation of neural firing properties and heterogeneity in synaptic connectivity affect the initiation and maintenance of synchronous network bursting in excitatory networks. We show that cells that display different levels of ACh modulation have differential roles in generating network activity: weakly modulated cells are necessary for burst initiation and provide synchronizing drive to the rest of the network, whereas strongly modulated cells provide the overall activity level necessary to sustain burst firing. By applying several quantitative measures of network activity, we further show that the existence of network bursting and its characteristics, such as burst duration and intraburst synchrony, are dependent on the fraction of cell types providing the synaptic connections in the network. These results suggest mechanisms underlying ACh modulation of brain oscillations and the modulation of seizure activity during sleep states.

  17. Heat and Mass Transfer during Hydrogen Generation in an Array of Fuel Bars of a BWR Using a Periodic Unit Cell

    Directory of Open Access Journals (Sweden)

    H. Romero-Paredes

    2012-01-01

    Full Text Available This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations.

  18. Southeast Regional Assessment Study: an assessment of the opportunities of solar electric power generation in the Southeastern United States

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-07-01

    The objective of this study was to identify and assess opportunities for demonstration and large scale deployment of solar electric facilities in the southeast region and to define the technical, economic, and institutional factors that can contribute to an accelerated use of solar energy for electric power generation. Graphs and tables are presented indicating the solar resource potential, siting opportunities, energy generation and use, and socioeconomic factors of the region by state. Solar electric technologies considered include both central station and dispersed solar electric generating facilities. Central stations studied include solar thermal electric, wind, photovoltaic, ocean thermal gradient, and biomass; dispersed facilities include solar thermal total energy systems, wind, and photovoltaic. The value of solar electric facilities is determined in terms of the value of conventional facilities and the use of conventional fuels which the solar facilities can replace. Suitable cost and risk sharing mechanisms to accelerate the commercialization of solar electric technologies in the Southeast are identified. The major regulatory and legal factors which could impact on the commercialization of solar facilities are reviewed. The most important factors which affect market penetration are reviewed, ways to accelerate the implementation of these technologies are identified, and market entry paths are identified. Conclusions and recommendations are presented. (WHK)

  19. Southeast Regional Assessment Study: an assessment of the opportunities of solar electric power generation in the Southeastern United States

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-07-01

    The objective of this study was to identify and assess opportunities for demonstration and large scale deployment of solar electric facilities in the southeast region and to define the technical, economic, and institutional factors that can contribute to an accelerated use of solar energy for electric power generation. Graphs and tables are presented indicating the solar resource potential, siting opportunities, energy generation and use, and socioeconomic factors of the region by state. Solar electric technologies considered include both central station and dispersed solar electric generating facilities. Central stations studied include solar thermal electric, wind, photovoltaic, ocean thermal gradient, and biomass; dispersed facilities include solar thermal total energy systems, wind, and photovoltaic. The value of solar electric facilities is determined in terms of the value of conventional facilities and the use of conventional fuels which the solar facilities can replace. Suitable cost and risk sharing mechanisms to accelerate the commercialization of solar electric technologies in the Southeast are identified. The major regulatory and legal factors which could impact on the commercialization of solar facilities are reviewed. The most important factors which affect market penetration are reviewed, ways to accelerate the implementation of these technologies are identified, and market entry paths are identified. Conclusions and recommendations are presented. (WHK)

  20. Operación eficiente de los bloques generador-transformadores en las unidades de generación distribuida; Efcient operation of generator-transformers blocks in distributed generations units

    Directory of Open Access Journals (Sweden)

    Marcos A. de Armas Teyra

    2012-11-01

    Full Text Available Este trabajo determinó la operación más eficiente de los bloques generador-transformador que entregan la energía eléctrica generada a una red de tensión superior. Hasta el momento la mayoría de los estudios realizados en este campo se basan en un análisis de la eficiencia relacionado con elestado de carga del conjunto. Este artículo propone un método para evaluar la eficiencia desde un espacio tridimensional que arroja una mejor solución al considerar el factor de potencia en el sistema. La optimización se realiza mediante la técnica de inteligencia artificial denominada enjambre departículas. El método propuesto puede emplearse para efectuar la compra o la selección del transformador más apropiado y para lograr la operación de estas unidades de la forma más eficiente y económica posible. Se muestra su aplicación a una unidad de 1150 kVA en la Provincia de Cienfuegos, Cuba.  In this paper was determined the most efficient operation of generator-transformers blocks of distributed generation unites that are operating to serve the electric power to a higher voltage grid. For this purpose, a tridimensional model of efficiency with better results is proposed taking into account the combined losses of the generator and transformer, the load level and the power factor of the system. In the optimization process a Particle Swarm algorithm was employed. The developed method can beused to select the transformer and to obtain the most efficient operation of these power plants as it is possible in field conditions. As an example its application to a 1150 kVA generation unite of Cienfuegos´s Province is shown.

  1. Power Enhancement Cavity for Burst-Mode Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yun [ORNL

    2015-01-01

    We demonstrate a novel optical cavity scheme and locking method that can realize the power enhancement of picosecond UV laser pulses operating at a burst mode with arbitrary burst (macropulse) lengths and repetition rates.

  2. THE FIVE YEAR FERMI/GBM MAGNETAR BURST CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Collazzi, A. C. [SciTec, Inc., 100 Wall Street, Princeton, NJ 08540 (United States); Kouveliotou, C.; Horst, A. J. van der; Younes, G. A. [Department of Physics, The George Washington University, 725 21st Street NW, Washington, DC 20052 (United States); Kaneko, Y.; Göğüş, E. [Sabancı University, Orhanlı-Tuzla, İstanbul 34956 (Turkey); Lin, L. [François Arago Centre, APC, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris (France); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Raanana 43537 (Israel); Finger, M. H. [Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Chaplin, V. L. [School of Medicine, Vanderbilt University, 1161 21st Avenue S, Nashville, TN 37232 (United States); Huppenkothen, D. [Center for Data Science, New York University, 726 Broadway, 7th Floor, New York, NY 10003 (United States); Watts, A. L. [Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Kienlin, A. von [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H., E-mail: acollazzi@scitec.com [Jacobs Technology, Inc., Huntsville, AL (United States); and others

    2015-05-15

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here, we present the Fermi/GBM magnetar catalog, providing the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from 2008 July to 2013 June. We provide durations, spectral parameters for various models, fluences, and peak fluxes for all the bursts, as well as a detailed temporal analysis for SGR J1550–5418 bursts. Finally, we suggest that some of the bursts of unknown origin are associated with the newly discovered magnetar 3XMM J185246.6+0033.7.

  3. Fast point-based method of a computer-generated hologram for a triangle-patch model by using a graphics processing unit.

    Science.gov (United States)

    Sugawara, Takuya; Ogihara, Yuki; Sakamoto, Yuji

    2016-01-20

    The point-based method and fast-Fourier-transform-based method are commonly used for calculation methods of computer-generation holograms. This paper proposes a novel fast calculation method for a patch model, which uses the point-based method. The method provides a calculation time that is proportional to the number of patches but not to that of the point light sources. This means that the method is suitable for calculating a wide area covered by patches quickly. Experiments using a graphics processing unit indicated that the proposed method is about 8 times or more faster than the ordinary point-based method.

  4. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    R.A.M.J. Wijers

    1999-01-01

    Gamma-ray bursts are much brighter than supernovae, and could therefore possibly probe the Universe to high redshift. The presently established GRB redshifts range from 0.83 to 5, and quite possibly even beyond that. Since most proposed mechanisms for GRB link them closely to deaths of massive stars

  5. Fast Radio Bursts: Searches, Sensitivities & Implications

    CERN Document Server

    Keane, E F

    2016-01-01

    Fast radio bursts (FRBs) are millisecond-duration transient signals discovered over the past decade. Here we describe the scientific usefulness of FRBs, consider ongoing work at the Parkes telescope, and examine some relevant search sensitivity and completeness considerations. We also look ahead to the results from ongoing and future planned studies in the field.

  6. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1999-01-01

    Gamma-ray bursts are much brighter than supernovae, and could therefore possibly probe the Universe to high redshift. The presently established GRB redshifts range from 0.83 to 5, and quite possibly even beyond that. Since most proposed mechanisms for GRB link them closely to deaths of massive stars

  7. IPN localizations of Konus short gamma-ray bursts

    CERN Document Server

    Pal'shin, V D; Svinkin, D S; Aptekar, R L; Golenetskii, S V; Frederiks, D D; Mazets, E P; Oleynik, P P; Ulanov, M V; Cline, T; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Boynton, W; Fellows, C; Harshman, K; Trombka, J; McClanahan, T; Starr, R; Goldsten, J; Gold, R; Rau, A; von Kienlin, A; Savchenko, V; Smith, D M; Hajdas, W; Barthelmy, S D; Cummings, J; Gehrels, N; Krimm, H; Palmer, D; Yamaoka, K; Ohno, M; Fukazawa, Y; Hanabata, Y; Takahashi, T; Tashiro, M; Terada, Y; Murakami, T; Makishima, K; Briggs, M S; Kippen, R M; Kouveliotou, C; Meegan, C; Fishman, G; Connaughton, V; Boer, M; Guidorzi, C; Frontera, F; Montanari, E; Rossi, F; Feroci, M; Amati, L; Nicastro, L; Orlandini, M; Monte, Del; Costa, E; Donnarumma, I; Evangelista, Y; Lapshov, I; Lazzarotto, F; Pacciani, L; Rapisarda, M; Soffitta, P; Di Cocco, G; Fuschino, F; Galli, M; Labanti, C; Marisaldi, M; Atteia, J -L; Vanderspek, R; Ricker, G

    2013-01-01

    Between the launch of the GGS Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 314 short-duration gamma-ray bursts (including 24 bursts which can be classified as short bursts with extended emission). During this period, the IPN consisted of up to eleven spacecraft, and using triangulation, the localizations of 276 bursts were obtained. We present the IPN localization data on these events.

  8. Important Developments in STEM Education in the United States: Next Generation Science Standards and Classroom Representations of Localized Scientific Activity

    Directory of Open Access Journals (Sweden)

    Todd Campbell

    2016-10-01

    Full Text Available This paper examines important recent developments in STEM education, especially related to science education in the United States (U.S.. This examination begins with an abbreviated introduction of the newest science standards documents in the U.S., with a specific focus on the structure and main priorities of these documents. This is followed by an explanation of why priority in the standards is given to teachers engaging students in science and engineering practices to use disciplinary scientific ideas in explaining phenomena and solving problems. Finally, attention is briefly given to how these standards documents hold promise for acting as leverage points within the complex U.S. educational system for positively influencing the disconcerting issues consistently reported in national studies of U.S. classrooms.

  9. BurstMem: A High-Performance Burst Buffer System for Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Teng [Auburn University, Auburn, Alabama; Oral, H Sarp [ORNL; Wang, Yandong [Auburn University, Auburn, Alabama; Settlemyer, Bradley W [ORNL; Atchley, Scott [ORNL; Yu, Weikuan [Auburn University, Auburn, Alabama

    2014-01-01

    The growth of computing power on large-scale sys- tems requires commensurate high-bandwidth I/O system. Many parallel file systems are designed to provide fast sustainable I/O in response to applications soaring requirements. To meet this need, a novel system is imperative to temporarily buffer the bursty I/O and gradually flush datasets to long-term parallel file systems. In this paper, we introduce the design of BurstMem, a high- performance burst buffer system. BurstMem provides a storage framework with efficient storage and communication manage- ment strategies. Our experiments demonstrate that BurstMem is able to speed up the I/O performance of scientific applications by up to 8.5 on leadership computer systems.

  10. Coordination Between Wind Power, Hydro Storage Facility and Conventional Generating Units According to the Annual Growth Load

    Directory of Open Access Journals (Sweden)

    Shahrokh Shojaeean

    2013-04-01

    Full Text Available Considering the growing trend of the consumption of the electric power and the global tendency to substitute new renewable sources of energy, this paper proposes a Monte Carlo based method to determine an optimal level of this change. Considering the limitation of the wind farms in continuous supply of electric power, hydrostatic power storage facilities are used beside wind farms so that the electric power could be stored and fed in a continuous flow into power systems. Due to the gradual exclusion of conventional generators and 5 percent annual load increments, LOLE index was used in order to calculate the amount of the wind power and the capacity of the necessary power storage facility. To this end, LOLE index was calculated for the first year as the reference index for the estimation of the amount of wind power and the capacity of the storage facility in consequent years. For the upcoming years, calculations have been made to account for the gradual exclusion of conventional generators in proportion to load increments. The proposed method has been implemented and simulated on IEEE-RTS test system.

  11. Detecting Pipe Bursts Using Heuristic and CUSUM Methods

    NARCIS (Netherlands)

    Bakker, M.; Jung, D.; Vreeburg, J.; Van de Roer, M.; Lansey, K.; Rierveld, L.

    2014-01-01

    Pipe bursts in a drinking water distribution system lead to water losses, interruption of supply, and damage to streets and houses due to the uncontrolled water flow. To minimize the negative consequences of pipe bursts, an early detection is necessary. This paper describes a heuristic burst detecti

  12. IGR J17254-3257, a new bursting neutron star

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Falanga, M.; Kuulkers, E.

    2007-01-01

    Aims. The study of the observational properties of uncommonly long bursts from low luminosity sources is important when investigating the transition from a hydrogen - rich bursting regime to a pure helium regime and from helium burning to carbon burning as predicted by current burst theories. On ...

  13. 46 CFR 154.554 - Cargo hose: Bursting pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure of...

  14. Thalamic Bursts Down-regulate Cortical Theta and Nociceptive Behavior.

    Science.gov (United States)

    LeBlanc, Brian W; Cross, Brent; Smith, Kelsey A; Roach, Catherine; Xia, Jimmy; Chao, Yu-Chieh; Levitt, Joshua; Koyama, Suguru; Moore, Christopher I; Saab, Carl Y

    2017-05-30

    We tested the relation between pain behavior, theta (4-8 Hz) oscillations in somatosensory cortex and burst firing in thalamic neurons in vivo. Optically-induced thalamic bursts attenuated cortical theta and mechanical allodynia. It is proposed that thalamic bursts are an adaptive response to pain that de-synchronizes cortical theta and decreases sensory salience.

  15. ESA's Integral detects closest cosmic gamma-ray burst

    Science.gov (United States)

    2004-08-01

    over 170 wafer-thin cylindrical mirrors spread over three telescopes. Its orbit takes it almost a third of the way to the Moon, so that astronomers can enjoy long, uninterrupted views of celestial objects. For more information about XMM-Newton please see: http://www.esa.int/esaSC/spk.html More about Chandra NASA's Marshall Space Flight Center, Huntsville, Alabama, manages the Chandra programme for the Office of Space Science, NASA Headquarters, Washington DC, USA. Northrop Grumman of Redondo Beach, California, formerly TRW Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Massachusetts. For more information about Chandra please see: http://chandra.harvard.edu/about More about the Very Large Array The Very Large Array (VLA) is a research facility of the United States National Science Foundation. With 27 dish antennas, each 25 metres in diameter, working together as a single imaging instrument, it is the most versatile and most widely used radio telescope in the world. Dedicated in 1980, the VLA has been used by thousands of scientists and has contributed valuable new information to nearly every specialty within astronomy. In 1997, the VLA made the first-ever detection of a gamma-ray burst afterglow at radio wavelengths, and has been at the forefront of gamma-ray burst afterglow research since.

  16. A codimension-2 bifurcation controlling endogenous bursting activity and pulse-triggered responses of a neuron model.

    Directory of Open Access Journals (Sweden)

    William H Barnett

    Full Text Available The dynamics of individual neurons are crucial for producing functional activity in neuronal networks. An open question is how temporal characteristics can be controlled in bursting activity and in transient neuronal responses to synaptic input. Bifurcation theory provides a framework to discover generic mechanisms addressing this question. We present a family of mechanisms organized around a global codimension-2 bifurcation. The cornerstone bifurcation is located at the intersection of the border between bursting and spiking and the border between bursting and silence. These borders correspond to the blue sky catastrophe bifurcation and the saddle-node bifurcation on an invariant circle (SNIC curves, respectively. The cornerstone bifurcation satisfies the conditions for both the blue sky catastrophe and SNIC. The burst duration and interburst interval increase as the inverse of the square root of the difference between the corresponding bifurcation parameter and its bifurcation value. For a given set of burst duration and interburst interval, one can find the parameter values supporting these temporal characteristics. The cornerstone bifurcation also determines the responses of silent and spiking neurons. In a silent neuron with parameters close to the SNIC, a pulse of current triggers a single burst. In a spiking neuron with parameters close to the blue sky catastrophe, a pulse of current temporarily silences the neuron. These responses are stereotypical: the durations of the transient intervals-the duration of the burst and the duration of latency to spiking-are governed by the inverse-square-root laws. The mechanisms described here could be used to coordinate neuromuscular control in central pattern generators. As proof of principle, we construct small networks that control metachronal-wave motor pattern exhibited in locomotion. This pattern is determined by the phase relations of bursting neurons in a simple central pattern generator

  17. Investigation of Primordial Black Hole Bursts using Interplanetary Network Gamma-ray Bursts

    CERN Document Server

    Ukwatta, T N; MacGibbon, J H; Svinkin, D S; Aptekar, R L; Golenetskii, S V; Frederiks, D D; Pal'shin, V D; Goldsten, J; Boynton, W; Fellows, C; Harshman, K; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Rau, A; Kienlin, A; Zhang, X; Briggs, M S; Connaughton, V; Meegan, C; Yamaoka, K; Fukazawa, Y; Ohno, M; Ohmori, N; Takahashi, T; Tashiro, M; Terada, Y; Murakami, T; Makishima, K; Feroci, M; Frontera, F; Guidorzi, C; Barthelmy, S; Cline, T; Gehrels, N; Cummings, J; Krimm, H A; Smith, D M; McTiernan, J

    2015-01-01

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating Primordial Black Holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the minimum distance to gamma-ray bursts using detections from widely separated spacecraft. We applied this method to constrain distances to a sample of 36 short duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 10^13-10^18 cm (7-10^5 AU) range, consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Assuming these bursts are real PBH events, we estimate for the first time lower limits ...

  18. Models for Gamma-Ray Bursts and Diverse Transients

    CERN Document Server

    Woosley, S E; 10.1098/rsta.2006.1997

    2008-01-01

    The observational diversity of ``gamma-ray bursts'' (GRBs) has been increasing, and the natural inclination is a proliferation of models. We explore the possibility that at least part of this diversity is a consequence of a single basic model for the central engine operating in a massive star of variable mass, differential rotation rate, and mass loss rate. Whatever that central engine may be - and here the collapsar is used as a reference point - it must be capable of generating both a narrowly collimated, highly relativistic jet to make the GRB, and a wide angle, sub-relativistic outflow responsible for exploding the star and making the supernova bright. To some extent, the two components may vary independently, so it is possible to produce a variety of jet energies and supernova luminosities. We explore, in particular, the production of low energy bursts and find a lower limit, $\\sim10^{48}$ erg s$^{-1}$ to the power required for a jet to escape a massive star before that star either explodes or is accrete...

  19. THE FIRST FERMI-LAT GAMMA-RAY BURST CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Asano, K. [Interactive Research Center of Science, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551 (Japan); Axelsson, M. [Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bechtol, K.; Bloom, E. D. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bhat, P. N. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Bissaldi, E. [Institut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck (Austria); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bonnell, J.; Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bouvier, A., E-mail: nicola.omodei@stanford.edu, E-mail: giacomov@slac.stanford.edu [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); and others

    2013-11-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (∼> 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ∼20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  20. Thermonuclear burst oscillations: where firestorms meet fundamental physics.

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Neutron stars offer a unique environment in which to develop and test theories of the strong force. Densities in neutron star cores can reach up to ten times the density of a normal atomic nucleus, and the stabilising effect of gravitational confinement permits long-timescale weak interactions. This generates matter that is neutron-rich, and opens up the possibility of stable states of strange matter, something that can only exist in neutron stars. Strong force physics is encoded in the Equation of State (EOS), the pressure-density relation, which links to macroscopic observables such as mass M and radius R via the stellar structure equations. By measuring and inverting the M-R relation we can recover the EOS and diagnose the underlying dense matter physics. One very promising technique for simultaneous measurement of M and R exploits hotspots (burst oscillations) that form on the neutron star surface when material accreted from a companion star undergoes a thermonuclear explosion (a Type I X-ray burst). As ...

  1. The First Fermi-LAT Gamma-Ray Burst Catalog

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Dingus, B. L.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Ferrara, E. C.; Fitzpatrick, G.; Foley, S.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Grenier, I. A.; Grove, J. E.; Gruber, D.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Murgia, S.; Nemmen, R.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Pelassa, V.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romoli, C.; Roth, M.; Ryde, F.; Saz Parkinson, P. M.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tierney, D.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vianello, G.; Vitale, V.; von Kienlin, A.; Winer, B. L.; Wood, K. S.; Wood, M.; Xiong, S.; Yang, Z.

    2013-11-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ~20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  2. The First FERMI-LAT Gamma-Ray Burst Catalog

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Ferrara, E. C.; Gehrels, N.; Guiriec, S.; McEnery, J. E.; Nemmen, R.; Perkins, J. S.; Racusin, J. L.; Thompson, D. J.; Kouveliotou, C.

    2013-01-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy great than (20 MeV) gamma-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above approximately 20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  3. Observations of Traveling Ionospheric Disturbances (TIDs) Over the United States Associated With the Tsunami Generated by the 2011 Tohoku Earthquake

    Science.gov (United States)

    Duly, T. M.; Azeem, I.; Crowley, G.; Vadas, S.; Makela, J. J.; Reynolds, A.

    2015-12-01

    The March 11, 2011 Tohoku earthquake generated a massive tsunami off the Pacific coast of Japan which in turn forced intense atmospheric gravity waves (AGW) that were seen in GPS Total Electron Content (TEC) data and airglow measurements as traveling ionospheric disturbance (TID) signatures as far away as Hawaii. What is unknown is how far these TIDs traveled after being launched by the tsunami and the role of the underlying neutral atmosphere on their propagation characteristics. For the first time, we show that TIDs associated with the Tohoku tsunami were observed in GPS TEC data for several hours over the west coast of the US and as far inland as Colorado. The results presented here show a range of TIDs generated by gravity wave packets propagating into the ionosphere from below. We present results indicating the presence of TIDs with periods ranging from 15 to 30 minutes, and horizontal wavelengths from 150 km to 400 km. The azimuth of the observed TID wave train was 121.8 ± 1.8° (angle measured in degrees east of north), which matches the azimuth of the tsunami near the Pacific coast of the US. The observed period of the TIDs was one of the spectral components of the tsunami wave packet as it approached the Pacific coast of the US. These results suggest that the tsunami was the source of the TIDs over the US. Additionally, the TID periods and horizontal wavelengths clearly vary in longitude. These variations agree with theoretical gravity wave results concerning propagation and dissipation in the thermosphere.

  4. The underestimated challenges of burst-mode WDM transmission in TWDM-PON

    Science.gov (United States)

    Bonk, R.; Poehlmann, W.; van Veen, D.; Galaro, J.; Farah, R.; Schmuck, H.; Pfeiffer, Th.

    2015-12-01

    In this paper, the underestimated challenges of the burst-mode operation in the upstream path of time-and-wavelength-division-multiplexed passive optical networks are analyzed. Various challenges are disclosed, the influence of the associated physical effects on the signal quality is discussed and mitigation proposals are described: Intra-channel cross-talk can arise from optical network units induced background amplified-spontaneous emission noise and inter-channel cross-talk can be caused by non-ideal filter suppression between wavelength channels at the optical line termination receivers. Such cross-talk effects can be counteracted by reducing the laser burst-signal output power as well as its rival noise power simultaneously, i.e. by applying power leveling. A fast frequency drift in burst-mode operation is inherent to directly modulated lasers, but depends on the specific laser design, the laser output power and the burst length. Mitigation mechanisms are an optimized non-standard laser design or a specific mode of operation, e.g. an increase of the frequency drift during the preamble of the burst. The power dynamic range an optical pre-amplifier as part of the upstream signal receivers needs to handle can be in range of up to 40 dB, because of the multi-wavelength channel operation and of the optical distribution network differential path loss. This power dynamic faced at the receiver can not only cause challenges for the optical amplifier, but also for the burst-mode receivers. Additionally, the physical layer operation and maintenance of the upstream path is challenging too. Each optical network unit laser needs to be either wavelength pre-calibrated, which adds undesired costs or cross-channel synchronization of ranging windows has to be ensured. Otherwise rogue optical network unit behavior in wavelength and time domain will deteriorate system performance with every new optical network unit entering the network. Further, the operation of the optical

  5. Healthcare reform and the next generation: United States medical student attitudes toward the Patient Protection and Affordable Care Act.

    Directory of Open Access Journals (Sweden)

    Kristin M Huntoon

    Full Text Available CONTEXT: Over one year after passage of the Patient Protection and Affordable Care Act (PPACA, legislators, healthcare experts, physicians, and the general public continue to debate the implications of the law and its repeal. The PPACA will have a significant impact on future physicians, yet medical student perspectives on the legislation have not been well documented. OBJECTIVE: To evaluate medical students' understanding of and attitudes toward healthcare reform and the PPACA including issues of quality, access and cost. DESIGN, SETTING, AND PARTICIPANTS: An anonymous electronic survey was sent to medical students at 10 medical schools (total of 6982 students between October-December 2010, with 1232 students responding and a response rate of 18%. MAIN OUTCOME MEASURES: Medical students' views and attitudes regarding the PPACA and related topics, measured with Likert scale and open response items. RESULTS: Of medical students surveyed, 94.8% agreed that the existing United States healthcare system needs to be reformed, 31.4% believed the PPACA will improve healthcare quality, while 20.9% disagreed and almost half (47.7% were unsure if quality will be improved. Two thirds (67.6% believed that the PPACA will increase access, 6.5% disagreed and the remaining 25.9% were unsure. With regard to containing healthcare costs, 45.4% of participants indicated that they are unsure if the provisions of the PPACA will do so. Overall, 80.1% of respondents indicated that they support the PPACA, and 78.3% also indicated that they did not feel that reform efforts had gone far enough. A majority of respondents (58.8% opposed repeal of the PPACA, while 15.0% supported repeal, and 26.1% were undecided. CONCLUSION: The overwhelming majority of medical students recognized healthcare reform is needed and expressed support for the PPACA but echoed concerns about whether it will address issues of quality or cost containment.

  6. Time dynamics of burst-train filamentation assisted femtosecond laser machining in glasses.

    Science.gov (United States)

    Esser, Dagmar; Rezaei, Saeid; Li, Jianzhao; Herman, Peter R; Gottmann, Jens

    2011-12-05

    Bursts of femtosecond laser pulses with a repetition rate of f = 38.5MHz were created using a purpose-built optical resonator. Single Ti:Sapphire laser pulses, trapped inside a resonator and released into controllable burst profiles by computer generated trigger delays to a fast Pockels cell switch, drove filamentation-assisted laser machining of high aspect ratio holes deep into transparent glasses. The time dynamics of the hole formation and ablation plume physics on 2-ns to 400-ms time scales were examined in time-resolved side-view images recorded with an intensified-CCD camera during the laser machining process. Transient effects of photoluminescence and ablation plume emissions confirm the build-up of heat accumulation effects during the burst train, the formation of laser-generated filaments and plume-shielding effects inside the deeply etched vias. The small time interval between the pulses in the present burst train enabled a more gentle modification in the laser interaction volume that mitigated shock-induced microcracks compared with single pulses.

  7. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Pal' shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Cline, T.; Trombka, J.; McClanahan, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Boynton, W.; Fellows, C.; Harshman, K., E-mail: val@mail.ioffe.ru [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); and others

    2013-08-15

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  8. An Analysis of Burst Disc Pressure Instability

    Energy Technology Data Exchange (ETDEWEB)

    S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

    2000-06-01

    During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation

  9. Small disturbances stability analysis applied in a radial distribution system with distributed generation units; Analise de estabilidade a pequenos disturbios aplicada em um sistema de distribuicao radial com unidades de geracao distribuida

    Energy Technology Data Exchange (ETDEWEB)

    Dorca, Daniel Azevedo; Camacho, Jose Roberto [Universidade Federal de Uberlandia (UFU), MG (Brazil). Curso de Mestrado em Engenharia Eletrica

    2008-07-01

    This work investigates the small-disturbance stability of a 30 bus radial distribution system with distributed generation units. This work is realized through the time domain simulations and through the eigenvalue analysis and participation factors. The eigenvalue analysis show that is possible to predict a possible system instability face to a disturbance. The development of this work was stimulated by the increasing of the distributed generation units in the distribution networks. (author)

  10. HUBBLE STAYS ON TRAIL OF FADING GAMMA-RAY BURST FIREBALL

    Science.gov (United States)

    2002-01-01

    A Hubble Space Telescope image of the fading fireball from one of the universe's most mysterious phenomena, a gamma-ray burst. Though the visible component has faded to 1/500th its brightness (27.7 magnitude) from the time it was first discovered by ground- based telescopes last March (the actual gamma-ray burst took place on February 28), Hubble continues to clearly see the fireball and discriminated a surrounding nebulosity (at 25th magnitude) which is considered a host galaxy. The continued visibility of the burst, and the rate of its fading, support theories that the light from a gamma-ray burst is an expanding relativistic (moving near the speed of light) fireball, possibly produced by the collision of two dense objects, such as an orbiting pair of neutron stars. If the burst happened nearby, within our own galaxy, the resulting fireball should have had only enough energy to propel it into space for a month. The fact that this fireball is still visible after six months means the explosion was truly titanic and, to match the observed brightness, must have happened at the vast distances of galaxies. The energy released in a burst, which can last from a fraction of a second to a few hundred seconds, is equal to all of the Sun's energy generated over its 10 billion year lifetime. The false-color image was taken Sept. 5, 1997 with the Space Telescope Imaging Spectrograph. Credit: Andrew Fruchter (STScI), Elena Pian (ITSRE-CNR), and NASA

  11. Information-theoretic approach to the gravitational-wave burst detection problem

    Science.gov (United States)

    Lynch, Ryan; Vitale, Salvatore; Essick, Reed; Katsavounidis, Erik; Robinet, Florent

    2017-05-01

    The observational era of gravitational-wave astronomy began in the fall of 2015 with the detection of GW150914. One potential type of detectable gravitational wave is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a detection algorithm for such burst events—oLIB—that can be used in low latency to identify gravitational-wave transients. This algorithm consists of (1) an excess-power event generator based on the Q transform—Omicron—, (2) coincidence of these events across a detector network, and (3) an analysis of the coincident events using a Markov chain Monte Carlo Bayesian evidence calculator—LALInferenceBurst. These steps compress the full data streams into a set of Bayes factors for each event. Through this process, we use elements from information theory to minimize the amount of information regarding the signal-versus-noise hypothesis that is lost. We optimally extract this information using a likelihood-ratio test to estimate a detection significance for each event. Using representative archival LIGO data across different burst waveform morphologies, we show that the algorithm can detect gravitational-wave burst events of astrophysical strength in realistic instrumental noise. We also demonstrate that the combination of Bayes factors by means of a likelihood-ratio test can improve the detection efficiency of a gravitational-wave burst search. Finally, we show that oLIB's performance is robust against the choice of gravitational-wave populations used to model the likelihood-ratio test likelihoods.

  12. GridSample: an R package to generate household survey primary sampling units (PSUs) from gridded population data.

    Science.gov (United States)

    Thomson, Dana R; Stevens, Forrest R; Ruktanonchai, Nick W; Tatem, Andrew J; Castro, Marcia C

    2017-07-19

    Household survey data are collected by governments, international organizations, and companies to prioritize policies and allocate billions of dollars. Surveys are typically selected from recent census data; however, census data are often outdated or inaccurate. This paper describes how gridded population data might instead be used as a sample frame, and introduces the R GridSample algorithm for selecting primary sampling units (PSU) for complex household surveys with gridded population data. With a gridded population dataset and geographic boundary of the study area, GridSample allows a two-step process to sample "seed" cells with probability proportionate to estimated population size, then "grows" PSUs until a minimum population is achieved in each PSU. The algorithm permits stratification and oversampling of urban or rural areas. The approximately uniform size and shape of grid cells allows for spatial oversampling, not possible in typical surveys, possibly improving small area estimates with survey results. We replicated the 2010 Rwanda Demographic and Health Survey (DHS) in GridSample by sampling the WorldPop 2010 UN-adjusted 100 m × 100 m gridded population dataset, stratifying by Rwanda's 30 districts, and oversampling in urban areas. The 2010 Rwanda DHS had 79 urban PSUs, 413 rural PSUs, with an average PSU population of 610 people. An equivalent sample in GridSample had 75 urban PSUs, 405 rural PSUs, and a median PSU population of 612 people. The number of PSUs differed because DHS added urban PSUs from specific districts while GridSample reallocated rural-to-urban PSUs across all districts. Gridded population sampling is a promising alternative to typical census-based sampling when census data are moderately outdated or inaccurate. Four approaches to implementation have been tried: (1) using gridded PSU boundaries produced by GridSample, (2) manually segmenting gridded PSU using satellite imagery, (3) non-probability sampling (e.g. random-walk, "spin

  13. Electricity Generation, Electricity Consumption, and Energy Efficiency in the United States: A Dual Climatic-Behavioral Approach

    Science.gov (United States)

    Craig, Christopher Alan

    Much of the United States (US) has seen an increase in warm days, decrease in cool days, and increase in extreme weather events. These trends are projected to continue across much of the US and in turn increase the demand for electricity and subsequent greenhouse gas emissions. Ambitious energy efficiency (EE) programs are used across the US by energy utility organizations to reduce electricity demand and emissions. This study examined the impact of climatic variability on electricity consumption, as well as how pro-conservation interventions such as EE programs and experiential learning can be utilized to mitigate residential electricity consumption and emissions. Chapter 2 of this study examined the impact of EE programs on residential electricity consumption taking into account climatic indicators across the contiguous US. A state-by-state analysis suggested that climatic indicators were more explanatory of residential consumption than energy utility organization EE efforts at the state-level. Chapter 3 examined residential electricity consumption for heating and cooling applications explained by energy utility organization EE efforts and climatic indicators in the Southeast US. Indirect spending on EE programs was significantly related to heating and cooling applications and heating degree days, a climatic indicator for number of days over a certain temperature, were significantly related to cooling equipment applications. A survey of 2,450 residential electricity consumers was analyzed. Residents who were aware of EE programs and participated in EE programs were significantly more likely than those who were not to support energy utility organization use of clean energy and government subsidies for EE programs. Chapter 4 provided case study in a Southeast US state where a pro-conservation behavioral intervention was deployed in an elementary school. This chapter utilized a longitudinal design and mixed methodology to assess the effect of curriculum

  14. On the Implementation of Variable Speed in Pump-Turbine Units Providing Primary and Secondary Load-Frequency Control in Generating Mode

    Directory of Open Access Journals (Sweden)

    José Ignacio Sarasúa

    2015-12-01

    Full Text Available This paper analyses different control strategies for the speed control loop of a variable-speed pump-turbine unit equipped with a doubly fed induction generator, operating in generating mode in an isolated power system with high penetration of intermittent renewable energy. The control strategies are evaluated and compared to each other in terms of the amount of water discharged through the pump-turbine and of the wicket gates fatigue while providing primary and secondary load-frequency control. The influence of the penstock length and the initial operating point on the performance of each control strategy is studied in detail. For these purposes, several simulations have been performed with a suitable dynamic model of the pumped-storage hydropower plant and the power system. The results of the paper indicate that a proper control strategy would consist in updating the reference speed according to the power generation schedule and keeping it constant within each scheduling period (typically 1 h.

  15. A Strange Supernova with a Gamma-Ray Burst

    Science.gov (United States)

    1998-10-01

    1998bw is obviously an unusual supernova. It is therefore of particular significance that a Gamma-Ray Burst was observed from the same sky region just before it was discovered in optical light. It is very unlikely that these two very rare events would happen in the same region of the sky without being somehow related. Most astronomers therefore tend to believe that the gamma-rays do indeed originate in the supernova explosion. But can a single supernova be sufficiently energetic to produce a powerful Gamma-Ray Burst? New theoretical calculations, also published today in Nature, indicate that this may be so. Moreover, if the Gamma-Ray Burst observed on April 25 did originate in this supernova that is located in a relatively nearby galaxy, it was intrinsically much fainter than some of the other Gamma-Ray Bursts that are known to have taken place in extremely distant galaxies. The main idea is that while the centres of most other supernovae collapse into neutron stars at the moment of explosion, a black hole was created in a very massive star consisting mostly of carbon and oxygen. If so, a very strong shockwave may be produced that is capable of generating the observed gamma rays. A comparison of synthetic spectra from such a supernova model, based on a new spectrum-modelling technique developed by Leon Lucy at the ESA/ESO Space Telescope/European Coordinating Facility (ST/ECF), with the spectra of SN 1998bw observed at La Silla, show good agreement, thus lending credibility to the new models. Future work Much data has already been collected at ESO on the strange supernova SN 1998bw . More observations will be obtained by the astronomers at the ESO observatories in the future during a long-term monitoring programme of SN 1998bw . There is a good chance that this effort will ultimately provide fundamental information on the explosion mechanism and the nature of the progenitor star of this exceptional object. This supernova's connection with a Gamma-Ray Burst will

  16. On associating Fast Radio Bursts with afterglows

    CERN Document Server

    Vedantham, H K; Mooley, K; Frail, D; Hallinan, G; Kulkarni, S R

    2016-01-01

    A radio source that faded over 6 days, with a redshift $z\\approx0.5$ host, has been identified by Keane et al. (2016) as the transient afterglow to a Fast Radio Burst (FRB 150418). We report follow-up radio and optical observations of the afterglow candidate, and find a source that is consistent with an active galactic nucleus (AGN). If the afterglow-candidate is nonetheless a prototypical FRB afterglow, existing surveys limit the fraction of FRBs that produce afterglows to 0.25 for modulation-index $m=\\Delta S/\\bar{S}\\geq0.7$, and 0.07 for $m\\geq1$, at 95\\% confidence. Afterglow associations with the barrage of bursts expected from future FRB surveys must satisfy constraints on the afterglow rate set by state of the art slow-transient surveys.

  17. PQMon: a powerful veto for burst events

    Science.gov (United States)

    Kötter, K.; Heng, I. S.; Hewitson, M.; Strain, K. A.; Woan, G.; Ward, H.

    2003-09-01

    Data taken by the gravitational wave detector GEO 600 (Danzmann K et al 1994 GEO 600—Proposal for a 600m Laser-Interferometric Gravitational Wave Antenna (Garching: MPQ)) during the science run 'S1' contain a large number of transients. In order to reduce the false-alarm rate of burst gravitational wave search algorithms it is desirable to veto all those transients that are clearly not of gravitational wave origin. This paper presents a method of vetoing transients by looking at the 'in-phase' (P) and 'quadrature' (Q) channels of the demodulated interferometer output signal. By taking advantage of the fact that the P-channel and the Q-channel have different sensitivities to gravitational wave burst events, this method can veto transients that have a power distribution different from the signature of a signal induced by a gravitational wave.

  18. Burst Detector X-Ray IIR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The Burst Detector X-Ray (BDX) instrument for the Block IIR series of Global Positioning System satellites is described. The BDX instrument can locate and characterize exoatmospheric nuclear detonations by using four sensors consisting of sets of filters over silicon diodes to detect x rays of various energies from the burst. On the BDX-IIR, a fifth sensor with a response spanning those of the other sensors confirms coincidences among the four main channels. The mechanical and electronic features of the BDX-IIR and its sensors are described. The calibrations and the system tests used in flight are presented. The commands for the BDX-IIR are given. The messages sent from the BDX-IIR are described in detail.

  19. Coherence resonance in bursting neural networks.

    Science.gov (United States)

    Kim, June Hoan; Lee, Ho Jun; Min, Cheol Hong; Lee, Kyoung J

    2015-10-01

    Synchronized neural bursts are one of the most noticeable dynamic features of neural networks, being essential for various phenomena in neuroscience, yet their complex dynamics are not well understood. With extrinsic electrical and optical manipulations on cultured neural networks, we demonstrate that the regularity (or randomness) of burst sequences is in many cases determined by a (few) low-dimensional attractor(s) working under strong neural noise. Moreover, there is an optimal level of noise strength at which the regularity of the interburst interval sequence becomes maximal-a phenomenon of coherence resonance. The experimental observations are successfully reproduced through computer simulations on a well-established neural network model, suggesting that the same phenomena may occur in many in vivo as well as in vitro neural networks.

  20. Are gamma-ray bursts cosmological?

    CERN Document Server

    Horvath, I

    2015-01-01

    Gamma-ray burst sources are distributed with a high level of isotropy, which is compatible with either a cosmological origin or an extended Galactic halo origin. The brightness distribution is another indicator used to characterize the spatial distribution in distance. In this paper the author discusses detailed fits of the BATSE gamma-ray burst peak-flux distributions with Friedmann models taking into account possible density evolution and standard candle luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and the author derives the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable