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Sample records for extremely high current

  1. High latitude equivalent current systems during extremely quiet times

    NASA Technical Reports Server (NTRS)

    Rostoker, G.; Chen, A. J.; Yasuhara, F.; Akasofu, S.-I.; Kawasaki, K.

    1974-01-01

    The magnetic perturbation patterns in the polar cap and auroral zone regions are obtained for extremely quiet days using two different techniques. It is shown that the form of the equivalent current flow pattern is extremely sensitive to the level of quietness, and that even so-called quiet days are at times disturbed by substorm activity. Certain characteristic equivalent flow not typically observed during substorms is noted in the polar cap, and this flow appears to be associated with effects of polar cap perturbations discussed by Svalgaard (1973). A region of equatorward flow at high latitudes near the dawn meridian, appears to be Hall current driven by an eastward electric field. The dayside sub-auroral zone is dominated by the Sq-current system, while the nightside shows no significant current flow in the absence of substorm activity.

  2. Extremely High Current, High-Brightness Energy Recovery Linac

    SciTech Connect

    I. Ben-Zvi; D.S. Barton; D.B. Beavis; M. Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X.Y. Chang; R. Connolly; D.M. Gassner; J.G. Grimes; H. Hahn; A. Hershcovitch; H.-C. Hseuh; P.D.J. Johnson; D. Kayran; J. Kewisch; R.F. Lambiase; V. Litvinenko; G.T. McIntyre; W. Meng; T.C.N. Nehring; T. Nicoletti; B. Oerter; D. Pate; J. Rank; T. Rao; T. Roser; T. Russo; J. Scaduto; Z. Segalov; K. Smith; N.W.W. Williams; K.-C. Wu; V. Yakimenko; K. Yip; A. Zaltsman; Y. Zhao; H. Bluem; A. Burger; M.D. Cole; A.J. Favale; D. Holmes; J. Rathke; T. Schultheiss; A.M.M. Todd; J.R. Delayen; L. W. Funk; P. Kneisel; H.L. Phillips; J.P. Preble

    2005-05-16

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  3. Regional-Scale High-Latitude Extreme Geoelectric Fields Pertaining to Geomagnetically Induced Currents

    NASA Technical Reports Server (NTRS)

    Pulkkinen, Antti; Bernabeu, Emanuel; Eichner, Jan; Viljanen, Ari; Ngwira, Chigomezyo

    2015-01-01

    Motivated by the needs of the high-voltage power transmission industry, we use data from the high-latitude IMAGE magnetometer array to study characteristics of extreme geoelectric fields at regional scales. We use 10-s resolution data for years 1993-2013, and the fields are characterized using average horizontal geoelectric field amplitudes taken over station groups that span about 500-km distance. We show that geoelectric field structures associated with localized extremes at single stations can be greatly different from structures associated with regionally uniform geoelectric fields, which are well represented by spatial averages over single stations. Visual extrapolation and rigorous extreme value analysis of spatially averaged fields indicate that the expected range for 1-in-100-year extreme events are 3-8 V/km and 3.4-7.1 V/km, respectively. The Quebec reference ground model is used in the calculations.

  4. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    NASA Astrophysics Data System (ADS)

    Hirano, Y.; Kiyama, S.; Fujiwara, Y.; Koguchi, H.; Sakakita, H.

    2015-11-01

    A high current density (≈3 mA/cm2) hydrogen ion beam source operating in an extremely low-energy region (Eib ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when Eib is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  5. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region.

    PubMed

    Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

    2015-11-01

    A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge. PMID:26628125

  6. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    SciTech Connect

    Hirano, Y. E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp; Kiyama, S.; Koguchi, H.; Fujiwara, Y.; Sakakita, H.

    2015-11-15

    A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  7. High Resolution Simulation of a Colorado Rockies Extreme Snow and Rain Event in both a Current and Future Climate

    NASA Astrophysics Data System (ADS)

    Rasmussen, Roy; Ikeda, Kyoko; Liu, Changhai; Gutmann, Ethan; Gochis, David

    2016-04-01

    Modeling of extreme weather events often require very finely resolved treatment of atmospheric circulation structures in order to produce and localize the large moisture fluxes that result in extreme precipitation. This is particularly true for cool season orographic precipitation processes where the representation of the landform can significantly impact vertical velocity profiles and cloud moisture entrainment rates. This study presents results for high resolution regional climate modeling study of the Colorado Headwaters region using an updated version of the Weather Research and Forecasting (WRF) model run at 4 km horizontal resolution and a hydrological extension package called WRF-Hydro. Previous work has shown that the WRF modeling system can produce credible depictions of winter orographic precipitation over the Colorado Rockies if run at horizontal resolutions < 6 km. Here we present results from a detailed study of an extreme springtime snowfall event that occurred along the Colorado Front Range in March 2003. Results from the impact of warming on total precipitation, snow-rain partitioning and surface hydrological fluxes (evapotranspiration and runoff) will be discussed in the context of how potential changes in temperature impact the amount of precipitation, the phase of precipitation (rain vs. snow) and the timing and amplitude of streamflow responses. The results show using the Pseudo Global Warming technique that intense precipitation rates significantly increased during the event and a significant fraction of the snowfall converts to rain which significantly amplifies the runoff response from one where runoff is produced gradually to one in which runoff is rapidly translated into streamflow values that approach significant flooding risks. Results from a new, CONUS scale high resolution climate simulation of extreme events in a current and future climate will be presented as time permits.

  8. High frequencies of elevated alkaline phosphatase activity and rickets exist in extremely low birth weight infants despite current nutritional support

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osteopenia and rickets are common among extremely low birth weight infants (ELBW, <1000 g birth weight) despite current practices of vitamin and mineral supplementation. Few data are available evaluating the usual course of markers of mineral status in this population. Our objectives in this study w...

  9. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm-2

    NASA Astrophysics Data System (ADS)

    Tian, Pengfei; Althumali, Ahmad; Gu, Erdan; Watson, Ian M.; Dawson, Martin D.; Liu, Ran

    2016-04-01

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm-2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC.

  10. Left-Wing Extremism: The Current Threat

    SciTech Connect

    Karl A. Seger

    2001-04-30

    Left-wing extremism is ''alive and well'' both in the US and internationally. Although the current domestic terrorist threat within the U. S. is focused on right-wing extremists, left-wing extremists are also active and have several objectives. Leftist extremists also pose an espionage threat to U.S. interests. While the threat to the U.S. government from leftist extremists has decreased in the past decade, it has not disappeared. There are individuals and organizations within the U.S. who maintain the same ideology that resulted in the growth of left-wing terrorism in this country in the 1970s and 1980s. Some of the leaders from that era are still communicating from Cuba with their followers in the U.S., and new leaders and groups are emerging.

  11. High performance x-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Moet, Date; van der Steen, Jan Laurens; van Breemen, Albert; Shanmugam, Santhosh; Gilot, Jan; Andriessen, Ronn; Simon, Matthias; Ruetten, Walter; Douglas, Alexander; Raaijmakers, Rob; Malinowski, Pawel E.; Myny, Kris; Gelinck, Gerwin

    2015-10-01

    High performance X-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current Abhishek Kumara, Date Moeta, Albert van Breemena, Santhosh Shanmugama, Jan-Laurens van der Steena, Jan Gilota, Ronn Andriessena, Matthias Simonb, Walter Ruettenb, Alexander U. Douglasb, Rob Raaijmakersc, Pawel E. Malinowskid, Kris Mynyd and Gerwin H. Gelincka,e a. Holst Centre/TNO, High Tech Campus 31, Eindhoven 5656 AE, The Netherlands b. Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands c. Philips Healthcare, Veenpluis 6-8, 5684 PC Best, The Netherlands d. Department of Large Area Electronics, imec vzw, Kapeldreef 75, Leuven B3001, Belgium e. Applied Physics Department, TU Eindhoven, Eindhoven, The Netherlands We demonstrate high performance X-ray imaging detectors on foil suitable for medical grade X-ray imaging applications. The detectors are based on solution-processed organic photodiodes forming bulk-heterojunctions from photovoltaic donor and acceptor blend. The organic photodiodes are deposited using an industrially compatible slot die coating technique with end of line processing temperature below 100°C. These photodiodes have extremely low dark leakage current density of 10-7 mA/cm2 at -2V bias with very high yield and have peak absorption around 550 nm wavelength. We combine these organic photodiodes with high mobility metal oxide semiconductor based thin film transistor arrays with high pixel resolution of 200ppi on thin plastic substrate. When combined with a typical CsI(TI) scintillator material on top, they are well suited for low dose X-ray imaging applications. The optical crosstalk is insignificant upto resolution of 200 ppi despite the fact that the photodiode layer is one continuous layer and is non-pixelated. Low processing temperatures are another key advantage since they can be fabricated on plastic substrate. This implies that we can make X-ray detectors on flexible foil. Those

  12. Extremely high frequency RF effects on electronics.

    SciTech Connect

    Loubriel, Guillermo Manuel; Vigliano, David; Coleman, Phillip Dale; Williams, Jeffery Thomas; Wouters, Gregg A.; Bacon, Larry Donald; Mar, Alan

    2012-01-01

    The objective of this work was to understand the fundamental physics of extremely high frequency RF effects on electronics. To accomplish this objective, we produced models, conducted simulations, and performed measurements to identify the mechanisms of effects as frequency increases into the millimeter-wave regime. Our purpose was to answer the questions, 'What are the tradeoffs between coupling, transmission losses, and device responses as frequency increases?', and, 'How high in frequency do effects on electronic systems continue to occur?' Using full wave electromagnetics codes and a transmission-line/circuit code, we investigated how extremely high-frequency RF propagates on wires and printed circuit board traces. We investigated both field-to-wire coupling and direct illumination of printed circuit boards to determine the significant mechanisms for inducing currents at device terminals. We measured coupling to wires and attenuation along wires for comparison to the simulations, looking at plane-wave coupling as it launches modes onto single and multiconductor structures. We simulated the response of discrete and integrated circuit semiconductor devices to those high-frequency currents and voltages, using SGFramework, the open-source General-purpose Semiconductor Simulator (gss), and Sandia's Charon semiconductor device physics codes. This report documents our findings.

  13. Extreme Consumption Drinking Gaming and Prepartying among High School Students

    ERIC Educational Resources Information Center

    Tomaso, Cara C.; Zamboanga, Byron L.; Haas, Amie L.; Kenney, Shannon R.; Ham, Lindsay S.; Borsari, Brian

    2016-01-01

    Drinking games and prepartying (i.e., drinking before going to a social gathering/event) have emerged as high-risk drinking behaviors in high school students. The present study examines the current prepartying behaviors of high school students who report current participation in extreme-consumption games (e.g., chugging) with those who do not.…

  14. Extremely high current density over 1000 A/cm2 operation in M-GaN LEDs on bulk GaN substrates with low-efficiency droop

    NASA Astrophysics Data System (ADS)

    Yokogawa, Toshiya; Inoue, Akira

    2014-02-01

    A high current density over 1000 A/cm2 operation in small chip size m-plane GaN-LED has been successfully demonstrated. The LED with chip size 450 × 450 μm2 has emitted 1353 mW in light output power and 39.2% in external quantum efficiency (EQE) at 1000 A/cm2 (1134 mA). The m-plane GaN-LED has showed asymmetric radiation characteristics. The radiation patterns are controlled by the surface of LED package, the height of LED chip, and striped texture on top m-plane surface.

  15. Joint probability of extreme waves and currents on Norwegian shelf--

    SciTech Connect

    Heideman, J.C. ); Hagen, O. )

    1989-07-01

    Simultaneous wave and current measurements on the Norwegian Shelf were used to estimate the appropriate current to associate with extreme waves in platform design. The primary data consisted of seven years of measurements at Tromsoflaket (71{degrees}30'N, 19{degrees}E, 230 m depth), including 38 storms with peak significant wave heights above 7 m. The maximum wave height and maximum current occurred simultaneously in only one of the 38 storms. The wave and current time-series data were used to calculate the time series of drag load on a simple structure and statistics of wave height and drag load were developed. The data showed that the in-line current that must be added to extreme waves in order to preserve the extreme loads approaches 25 cm/s asymptotically as storm severity increases. Sensitivity studies suggest that this limit is largely insensitive to reasonable variations in current profile, wave kinematics theory, structure geometry, tidal current removal, length of data base, or site location. These results show that the current specified by Norwegian regulatory authorities is conservative, and provide a basis for reducing the design hydrodynamic loads on drag-dominated offshore structures on the Norwegian shelf.

  16. High PRF high current switch

    DOEpatents

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

  17. Extremely high energy neutrinos from cosmic strings

    SciTech Connect

    Berezinsky, Veniamin; Sabancilar, Eray; Vilenkin, Alexander

    2011-10-15

    Superstring theory and other supersymmetric theories predict the existence of relatively light, weakly interacting scalar particles, called moduli, with a universal form of coupling to matter. Such particles can be emitted from cusps of cosmic strings, where extremely large Lorentz factors are achieved momentarily. Highly boosted modulus bursts emanating from cusps subsequently decay into gluons; they generate parton cascades which in turn produce large numbers of pions and then neutrinos. Because of very large Lorentz factors, extremely high energy neutrinos, up to the Planck scale and above, are produced. For some model parameters, the predicted flux of neutrinos with energies > or approx. 10{sup 21} eV is observable by JEM-EUSO and by the future large radio detectors LOFAR and SKA.

  18. Extreme Transients in the High Energy Universe

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa

    2013-01-01

    The High Energy Universe is rich in diverse populations of objects spanning the entire cosmological (time)scale, from our own present-day Milky Way to the re-ionization epoch. Several of these are associated with extreme conditions irreproducible in laboratories on Earth. Their study thus sheds light on the behavior of matter under extreme conditions, such as super-strong magnetic fields (in excess of 10^14 G), high gravitational potentials (e.g., Super Massive Black Holes), very energetic collimated explosions resulting in relativistic jet flows (e.g., Gamma Ray Bursts, exceeding 10^53 ergs). In the last thirty years, my work has been mostly focused on two apparently different but potentially linked populations of such transients: magnetars (highly magnetized neutron stars) and Gamma Ray Bursts (strongly beamed emission from relativistic jets), two populations that constitute unique astrophysical laboratories, while also giving us the tools to probe matter conditions in the Universe to redshifts beyond z=10, when the first stars and galaxies were assembled. I did not make this journey alone I have either led or participated in several international collaborations studying these phenomena in multi-wavelength observations; solitary perfection is not sufficient anymore in the world of High Energy Astrophysics. I will describe this journey, present crucial observational breakthroughs, discuss key results and muse on the future of this field.

  19. Extremely compliant and highly stretchable patterned graphene

    NASA Astrophysics Data System (ADS)

    Zhu, Shuze; Huang, Yinjun; Li, Teng

    2014-04-01

    Graphene is intrinsically ultra-stiff in its plane. Its huge mechanical mismatch when interfacing with ultra-compliant biological tissues and elastomers (7-9 orders of magnitude difference in stiffness) poses significant challenge in its application to functional devices such as epidermal electronics and sensing prosthesis. We offer a feasible and promising solution to this significant challenge by suitably patterning graphene into a nanomesh. Through systematic coarse-grained simulations, we show that graphene nanomesh can be made extremely compliant with nearly zero stiffness up to about 20% elongation and then remain highly compliant up to about 50% elongation.

  20. High resolution extremity CT for biomechanics modeling

    SciTech Connect

    Ashby, A.E.; Brand, H.; Hollerbach, K.; Logan, C.M.; Martz, H.E.

    1995-09-23

    With the advent of ever more powerful computing and finite element analysis (FEA) capabilities, the bone and joint geometry detail available from either commercial surface definitions or from medical CT scans is inadequate. For dynamic FEA modeling of joints, precise articular contours are necessary to get appropriate contact definition. In this project, a fresh cadaver extremity was suspended in parafin in a lucite cylinder and then scanned with an industrial CT system to generate a high resolution data set for use in biomechanics modeling.

  1. Mitochondrial function at extreme high altitude.

    PubMed

    Murray, Andrew J; Horscroft, James A

    2016-03-01

    At high altitude, barometric pressure falls and with it inspired P(O2), potentially compromising O2 delivery to the tissues. With sufficient acclimatisation, the erythropoietic response increases red cell mass such that arterial O2 content (C(aO2)) is restored; however arterial P(O2)(P(aO2)) remains low, and the diffusion of O2 from capillary to mitochondrion is impaired. Mitochondrial respiration and aerobic capacity are thus limited, whilst reactive oxygen species (ROS) production increases. Restoration of P(aO2) with supplementary O2 does not fully restore aerobic capacity in acclimatised individuals, possibly indicating a peripheral impairment. With prolonged exposure to extreme high altitude (>5500 m), muscle mitochondrial volume density falls, with a particular loss of the subsarcolemmal population. It is not clear whether this represents acclimatisation or deterioration, but it does appear to be regulated, with levels of the mitochondrial biogenesis factor PGC-1α falling, and shows similarities to adapted Tibetan highlanders. Qualitative changes in mitochondrial function also occur, and do so at more moderate high altitudes with shorter periods of exposure. Electron transport chain complexes are downregulated, possibly mitigating the increase in ROS production. Fatty acid oxidation capacity is decreased and there may be improvements in biochemical coupling at the mitochondrial inner membrane that enhance O2 efficiency. Creatine kinase expression falls, possibly impairing high-energy phosphate transfer from the mitochondria to myofibrils. In climbers returning from the summit of Everest, cardiac energetic reserve (phosphocreatine/ATP) falls, but skeletal muscle energetics are well preserved, possibly supporting the notion that mitochondrial remodelling is a core feature of acclimatisation to extreme high altitude. PMID:26033622

  2. A Road Map to Extreme High Vacuum

    SciTech Connect

    Myneni, Ganapati Rao

    2007-06-20

    Ultimate pressure of a well-designed vacuum system very much depends on pretreatments, processing and the procedures [1,2]. Until now much attention has been paid in minimizing hydrogen outgassing from the chamber material. However, procedures and processing deserves further scrutiny than hitherto given so far. For reducing the gas load, high sensitivity helium leak detection techniques with sensitivities better than 1× 10-12 Torr l/sec need to be used. Effects that are induced by vacuum instrumentation need to be reduced in order to obtain accurate pressure measurements. This presentation will discuss: clean assembly procedures, metal sponges for cryosorption pumping of hydrogen to extreme high vacuum, low cost surface diffusion barriers for reducing the hydrogen gas load, cascade pumping, sensitive helium leak detection techniques and the use of modified extractor and residual gas analyzers. Further, alternative back up pumping systems based on active NEG’s [3] for turbo molecular pumps will be presented.

  3. Resuscitation of extremely preterm infants - controversies and current evidence

    PubMed Central

    Patel, Pooja N; Banerjee, Jayanta; Godambe, Sunit V

    2016-01-01

    Despite significant advances in perinatal medicine, the management of extremely preterm infants in the delivery room remains a challenge. There is an increasing evidence for improved outcomes regarding the resuscitation and stabilisation of extremely preterm infants but there is a lack of evidence in the periviable (gestational age 23-25 wk) preterm subgroup. Presence of an experienced team during the delivery of extremely preterm infant to improve outcome is reviewed. Adaptation from foetal to neonatal cardiorespiratory haemodynamics is dependent on establishing an optimal functional residual capacity in the extremely preterm infants, thus enabling adequate gas exchange. There is sufficient evidence for a gentle approach to stabilisation of these fragile infants in the delivery room. Evidence for antenatal steroids especially in the periviable infants, delayed cord clamping, strategies to establish optimal functional residual capacity, importance of temperature control and oxygenation in delivery room in extremely premature infants is reviewed in this article. PMID:27170925

  4. Resuscitation of extremely preterm infants - controversies and current evidence.

    PubMed

    Patel, Pooja N; Banerjee, Jayanta; Godambe, Sunit V

    2016-05-01

    Despite significant advances in perinatal medicine, the management of extremely preterm infants in the delivery room remains a challenge. There is an increasing evidence for improved outcomes regarding the resuscitation and stabilisation of extremely preterm infants but there is a lack of evidence in the periviable (gestational age 23-25 wk) preterm subgroup. Presence of an experienced team during the delivery of extremely preterm infant to improve outcome is reviewed. Adaptation from foetal to neonatal cardiorespiratory haemodynamics is dependent on establishing an optimal functional residual capacity in the extremely preterm infants, thus enabling adequate gas exchange. There is sufficient evidence for a gentle approach to stabilisation of these fragile infants in the delivery room. Evidence for antenatal steroids especially in the periviable infants, delayed cord clamping, strategies to establish optimal functional residual capacity, importance of temperature control and oxygenation in delivery room in extremely premature infants is reviewed in this article. PMID:27170925

  5. Extreme Precipitation and High-Impact Landslides

    NASA Technical Reports Server (NTRS)

    Kirschbaum, Dalia; Adler, Robert; Huffman, George; Peters-Lidard, Christa

    2012-01-01

    It is well known that extreme or prolonged rainfall is the dominant trigger of landslides; however, there remain large uncertainties in characterizing the distribution of these hazards and meteorological triggers at the global scale. Researchers have evaluated the spatiotemporal distribution of extreme rainfall and landslides at local and regional scale primarily using in situ data, yet few studies have mapped rainfall-triggered landslide distribution globally due to the dearth of landslide data and consistent precipitation information. This research uses a newly developed Global Landslide Catalog (GLC) and a 13-year satellite-based precipitation record from Tropical Rainfall Measuring Mission (TRMM) data. For the first time, these two unique products provide the foundation to quantitatively evaluate the co-occurence of precipitation and rainfall-triggered landslides globally. The GLC, available from 2007 to the present, contains information on reported rainfall-triggered landslide events around the world using online media reports, disaster databases, etc. When evaluating this database, we observed that 2010 had a large number of high-impact landslide events relative to previous years. This study considers how variations in extreme and prolonged satellite-based rainfall are related to the distribution of landslides over the same time scales for three active landslide areas: Central America, the Himalayan Arc, and central-eastern China. Several test statistics confirm that TRMM rainfall generally scales with the observed increase in landslide reports and fatal events for 2010 and previous years over each region. These findings suggest that the co-occurrence of satellite precipitation and landslide reports may serve as a valuable indicator for characterizing the spatiotemporal distribution of landslide-prone areas in order to establish a global rainfall-triggered landslide climatology. This research also considers the sources for this extreme rainfall, citing

  6. MAGNETIC RECONNECTION IN THE SOLAR WIND AT CURRENT SHEETS ASSOCIATED WITH EXTREMELY SMALL FIELD SHEAR ANGLES

    SciTech Connect

    Gosling, J. T.; Phan, T. D.

    2013-02-01

    Using Wind 3 s plasma and magnetic field data, we have identified nine reconnection exhausts within a solar wind disturbance on 1998 October 18-20 driven by a moderately fast interplanetary coronal mass ejection (ICME). Three of the exhausts within the ICME were associated with current sheets having local field shear angles, {theta}, ranging from 4 Degree-Sign to 9 Degree-Sign , the smallest reported values of {theta} yet associated with reconnection exhausts in a space plasma. They were observed in plasma characterized by extremely low (0.02-0.04) plasma {beta}, and very high (281-383 km s{sup -1}) Alfven speed, V{sub A}. Low {beta} allows reconnection to occur at small {theta} and high V{sub A} leads to exhaust jets that are fast enough relative to the surrounding solar wind to be readily identified. Very small-{theta} current sheets are common in the solar wind at 1 AU, but typically are not associated with particularly low plasma {beta} or high V{sub A}. On the other hand, small-{theta} current sheets should be common in the lower solar corona, a plasma regime of extremely low {beta} and extremely high V{sub A}. Our observations lend credence to models that predict that reconnection at small-{theta} current sheets is primarily responsible for coronal heating.

  7. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications

    NASA Astrophysics Data System (ADS)

    Ngwira, Chigomezyo M.; Pulkkinen, Antti; Wilder, Frederick D.; Crowley, Geoffrey

    2013-03-01

    Geomagnetically induced currents (GIC) flowing in man-made ground technological systems are a direct manifestation of adverse space weather. Today, there is great concern over possible geomagnetically induced current effects on power transmission networks that can result from extreme space weather events. The threat of severe societal consequences has accelerated recent interest in extreme geomagnetic storm impacts on high-voltage power transmission systems. As a result, extreme geomagnetic event characterization is of fundamental importance for quantifying the technological impacts and societal consequences of extreme space weather. This article reports on the global behavior of the horizontal geomagnetic field and the induced geoelectric field fluctuations during severe/extreme geomagnetic events. This includes (1) an investigation of the latitude threshold boundary, (2) the local time dependency of the maximum induced geoelectric field, and (3) the influence of the equatorial electrojet (EEJ) current on the occurrence of enhanced induced geoelectric fields over ground stations located near the dip equator. Using ground-based and satellite-borne Defense Meteorological Satellite Program measurements, this article confirms that the latitude threshold boundary is associated with the movements of the auroral oval and the corresponding auroral electrojet current system, which is the main driver of the largest perturbations of the ground geomagnetic field at high latitudes. In addition, we show that the enhancement of the EEJ is driven by the penetration of high-latitude electric fields and that the induced geoelectric fields at stations within the EEJ belt can be an order of magnitude larger than that at stations outside the belt. This has important implications for power networks located around the electrojet belt and confirms that earlier observations by Pulkkinen et al. (2012) were not isolated incidences but rather cases that can occur during certain severe

  8. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  9. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current application

    NASA Astrophysics Data System (ADS)

    Ngwira, C. M.; Pulkkinen, A.; Wilder, F. D.; Crowley, G.

    2012-12-01

    Geomagnetically induced currents (GIC) flowing in man-made ground technological systems are a direct manifestation of adverse space weather. Today there is great concern over possible GIC effects on power transmission networks that can result from extreme space weather events. The threat of severe societal consequences has accelerated recent interest in extreme geomagnetic storm impact on high-voltage power transmission systems. As a result, extreme geomagnetic event characterization is of fundamental importance for quantifying the technological impacts and societal consequences of extreme space weather. This paper reports on the global behavior of the horizontal geomagnetic field and the induced geoelectric field fluctuations during severe/extreme geomagnetic events. This includes: (1) an investigation of the latitude threshold boundary, (2) the local time dependency of the maximum geoelectric field, and (3) the influence of the equatorial electrojet (EEJ) on the occurrence of enhanced geoelectric fields over ground stations located near the dip equator. Using ground-based and satellite borne DMSP measurements, this paper confirms that the latitude threshold boundary is associated with the movements of the auroral oval and the associated auroral electrojet current system, which is the main driver of the largest perturbations of the ground geomagnetic field at high-latitudes. In addition, we show that the enhancement of the EEJ is associated with the penetration of high-latitude electric fields, and that the geoelectric fields around the EEJ belt can be an order of magnitude larger than stations outside the belt. This has important implications for power networks located around the electrojet belt, and confirms that earlier observations by Pulkkinen et al., (2012) were not isolated incidences, but rather cases that can occur during certain severe geomagnetic storm events.

  10. Anaerobic Life at Extremely High Temperatures

    NASA Astrophysics Data System (ADS)

    Stetter, Karl O.

    1984-12-01

    Continental and submarine solfataric fields turned out to contain various extremely thermophilic anaerobic organisms which all belong to the archaebacteria. They are living autotrophically on sulphur, hydrogen and CO2 or by methanogenesis or heterotrophically on different organic substrates by sulphur respiration or, less frequently, by fermentation. The most extremely thermophilic isolates are growing between 80 and 110°C with an optimum around 105°C.

  11. Survival in extreme environments - on the current knowledge of adaptations in tardigrades.

    PubMed

    Møbjerg, N; Halberg, K A; Jørgensen, A; Persson, D; Bjørn, M; Ramløv, H; Kristensen, R M

    2011-07-01

    Tardigrades are microscopic animals found worldwide in aquatic as well as terrestrial ecosystems. They belong to the invertebrate superclade Ecdysozoa, as do the two major invertebrate model organisms: Caenorhabditis elegans and Drosophila melanogaster. We present a brief description of the tardigrades and highlight species that are currently used as models for physiological and molecular investigations. Tardigrades are uniquely adapted to a range of environmental extremes. Cryptobiosis, currently referred to as a reversible ametabolic state induced by e.g. desiccation, is common especially among limno-terrestrial species. It has been shown that the entry and exit of cryptobiosis may involve synthesis of bioprotectants in the form of selective carbohydrates and proteins as well as high levels of antioxidant enzymes and other free radical scavengers. However, at present a general scheme of mechanisms explaining this phenomenon is lacking. Importantly, recent research has shown that tardigrades even in their active states may be extremely tolerant to environmental stress, handling extreme levels of ionizing radiation, large fluctuation in external salinity and avoiding freezing by supercooling to below -20 °C, presumably relying on efficient DNA repair mechanisms and osmoregulation. This review summarizes the current knowledge on adaptations found among tardigrades, and presents new data on tardigrade cell numbers and osmoregulation. PMID:21251237

  12. High temperature current mirror amplifier

    DOEpatents

    Patterson, R.B. III.

    1984-05-22

    Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

  13. Scanning tunnelling microscopy in extreme fields: very low temperature, high magnetic field, and extreme high vacuum

    NASA Astrophysics Data System (ADS)

    Sagisaka, Keisuke; Kitahara, Masayo; Fujita, Daisuke; Kido, Giyuu; Koguchi, Nobuyuki

    2004-06-01

    We present the performance of our newly developed very-low-temperature scanning tunnelling microscope (VLT-STM). This system can operate with high spatial and energy resolution at temperatures down to 350 mK, and in a magnetic field up to 11 T. The uniqueness of our VLT-STM is that the system possesses extreme-high-vacuum chambers (XHV) ({\\sim } 10^{-10} Pa). System operation ranges from sample preparation, such as cleaning and deposition, to observations in an extremely clean environment. XHV will have a significant impact within material sciences, particularly when treating a semiconductor surface. Test results have revealed STM images obtained below 1 K and with atomic resolution of highly oriented pyrolytic graphite (HOPG), Si(100) dimers, and Au(111) surfaces. Our Si(100) experiments are the first atomically-resolved STM images of the semiconductor surface obtained below 1 K. The results of those tests have conclusively determined its true ground state structure—a subject under debate for many years. Some of the STM images acquired in a high magnetic field are included in this paper. The XHV-VLT-STM system is state-of-the-art and a very powerful instrument for exploration of the nano-sciences.

  14. Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light

    NASA Astrophysics Data System (ADS)

    Turgut, Emrah

    Next-generation magnetic-memory devices and heat-assisted magnetic-recording applications will require a better understanding of magnetic multilayers and their interactions with optical-laser pulses. In this thesis, by combining the advantages of ultrabroad-band extreme-ultraviolet light including ultrafast time resolution, element selectivity and tabletop easy access, I report three findings in the study of ultrafast magnetization dynamics in itinerant ferromagnets. First, I experimentally prove that the transverse magneto-optical Kerr response with extreme-ultraviolet light has a purely magnetic origin and that our experimental technique is an artifact-free ultrafast magnetic probe. Second, I demonstrate the first ultrafast magnetization enhancement driven by ultrafast spin currents in Ni/Ru/Fe multilayers. Third, I engineer the sample system by choosing either insulating or spin-scattering spacer layers between the Ni and Fe magnetic layers and by structural ordering. Then, I control the competition between ultrafast spin-flip scattering and superdiffusive spin-current mechanisms; either of these processes may to be the dominant mechanism in ultrafast demagnetization. Finally, I report two continuing experiments that are promising for future ultrafast magnetization studies with extreme-ultraviolet sources. These experiments are resonant-magnetic small-angle-scattering and the generation of bright circularly polarized high harmonics accompanied by a demonstration of the first x-ray magnetic circular dichroism with a tabletop system.

  15. Extreme Environment Simulation - Current and New Capabilities to Simulate Venus and Other Planetary Bodies

    NASA Technical Reports Server (NTRS)

    Kremic, Tibor; Vento, Dan; Lalli, Nick; Palinski, Timothy

    2014-01-01

    Science, technology, and planetary mission communities have a growing interest in components and systems that are capable of working in extreme (high) temperature and pressure conditions. Terrestrial applications range from scientific research, aerospace, defense, automotive systems, energy storage and power distribution, deep mining and others. As the target environments get increasingly extreme, capabilities to develop and test the sensors and systems designed to operate in such environments will be required. An application of particular importance to the planetary science community is the ability for a robotic lander to survive on the Venus surface where pressures are nearly 100 times that of Earth and temperatures approach 500C. The scientific importance and relevance of Venus missions are stated in the current Planetary Decadal Survey. Further, several missions to Venus were proposed in the most recent Discovery call. Despite this interest, the ability to accurately simulate Venus conditions at a scale that can test and validate instruments and spacecraft systems and accurately simulate the Venus atmosphere has been lacking. This paper discusses and compares the capabilities that are known to exist within and outside the United States to simulate the extreme environmental conditions found in terrestrial or planetary surfaces including the Venus atmosphere and surface. The paper then focuses on discussing the recent additional capability found in the NASA Glenn Extreme Environment Rig (GEER). The GEER, located at the NASA Glenn Research Center in Cleveland, Ohio, is designed to simulate not only the temperature and pressure extremes described, but can also accurately reproduce the atmospheric compositions of bodies in the solar system including those with acidic and hazardous elements. GEER capabilities and characteristics are described along with operational considerations relevant to potential users. The paper presents initial operating results and concludes

  16. High current, high bandwidth laser diode current driver

    NASA Technical Reports Server (NTRS)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  17. Jets in AGN at extremely high redshifts

    NASA Astrophysics Data System (ADS)

    Gurvits, Leonid I.; Frey, Sándor; Paragi, Zsolt

    2015-03-01

    The jet phenomenon is a trademark of active galactic nuclei (AGN). In most general terms, the current understanding of this phenomenon explains the jet appearance by effects of relativistic plasma physics. The fundamental source of energy that feeds the plasma flow is believed to be the gravitational field of a central supermassive black hole. While the mechanism of energy transfer and a multitude of effects controlling the plasma flow are yet to be understood, major properties of jets are strikingly similar in a broad range of scales from stellar to galactic. They are supposed to be controlled by a limited number of physical parameters, such as the mass of a central black hole and its spin, magnetic field induction and accretion rate. In a very simplified sense, these parameters define the formation of a typical core-jet structure observed at radio wavelengths in the region of the innermost central tens of parsecs in AGN. These core-jet structures are studied in the radio domain by Very Long Baseline Interferometry (VLBI) with milli- and sub-milliarcsecond angular resolution. Such structures are detectable at a broad range of redshifts. If observed at a fixed wavelength, a typical core-jet AGN morphology would appear as having a steep-spectrum jet fading away with the increasing redshift while a flat-spectrum core becoming more dominant. If core-jet AGN constitute the same population of objects throughout the redshift space, the apparent ``prominence'' of jets at higher redshifts must decrease (Gurvits 1999): well pronounced jets at high z must appear less frequent than at low z.

  18. Towards High Accuracy Reflectometry for Extreme-Ultraviolet Lithography

    PubMed Central

    Tarrio, Charles; Grantham, Steven; Squires, Matthew B.; Vest, Robert E.; Lucatorto, Thomas B.

    2003-01-01

    Currently the most demanding application of extreme ultraviolet optics is connected with the development of extreme ultraviolet lithography. Not only does each of the Mo/Si multilayer extreme-ultraviolet stepper mirrors require the highest attainable reflectivity at 13 nm (nearly 70 %), but the central wavelength of the reflectivity of these mirrors must be measured with a wavelength repeatability of 0.001 nm and the peak reflectivity of the reflective masks with a repeatability of 0.12 %. We report on two upgrades of our NIST/DARPA Reflectometry Facility that have given us the ability to achieve 0.1 % repeatability and 0.3 % absolute uncertainty in our reflectivity measurements. A third upgrade, a monochromator with thermal and mechanical stability for improved wavelength repeatability, is currently in the design phase.

  19. HIGH VOLTAGE, HIGH CURRENT SPARK GAP SWITCH

    DOEpatents

    Dike, R.S.; Lier, D.W.; Schofield, A.E.; Tuck, J.L.

    1962-04-17

    A high voltage and current spark gap switch comprising two main electrodes insulatingly supported in opposed spaced relationship and a middle electrode supported medially between the main electrodes and symmetrically about the median line of the main electrodes is described. The middle electrode has a perforation aligned with the median line and an irradiation electrode insulatingly supported in the body of the middle electrode normal to the median line and protruding into the perforation. (AEC)

  20. High-current, high-frequency capacitors

    NASA Technical Reports Server (NTRS)

    Renz, D. D.

    1983-01-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  1. High current high accuracy IGBT pulse generator

    SciTech Connect

    Nesterov, V.V.; Donaldson, A.R.

    1995-05-01

    A solid state pulse generator capable of delivering high current triangular or trapezoidal pulses into an inductive load has been developed at SLAC. Energy stored in a capacitor bank of the pulse generator is switched to the load through a pair of insulated gate bipolar transistors (IGBT). The circuit can then recover the remaining energy and transfer it back to the capacitor bank without reversing the capacitor voltage. A third IGBT device is employed to control the initial charge to the capacitor bank, a command charging technique, and to compensate for pulse to pulse power losses. The rack mounted pulse generator contains a 525 {mu}F capacitor bank. It can deliver 500 A at 900V into inductive loads up to 3 mH. The current amplitude and discharge time are controlled to 0.02% accuracy by a precision controller through the SLAC central computer system. This pulse generator drives a series pair of extraction dipoles.

  2. HIGH CURRENT COAXIAL PHOTOMULTIPLIER TUBE

    DOEpatents

    Glass, N.W.

    1960-01-19

    A medium-gain photomultiplier tube having high current output, fast rise- time, and matched output impedance was developed. The photomultiplier tube comprises an elongated cylindrical envelope, a cylindrical anode supported at the axis of the envelope, a plurality of elongated spaced opaque areas on the envelope, and a plurality of light admitting windows. A photo-cathode is supported adjacent to each of the windows, and a plurality of secondary emissive dynodes are arranged in two types of radial arrays which are alternately positioned to fill the annular space between the anode and the envelope. The dynodes are in an array being radially staggered with respect to the dynodes in the adjacent array, the dynodes each having a portion arranged at an angle with respect to the electron path, such that electrons emitted by each cathode undergo multiplication upon impingement on a dynode and redirected flight to the next adjacent dynode.

  3. High current capacity electrical connector

    DOEpatents

    Bettis, Edward S.; Watts, Harry L.

    1976-01-13

    An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the busses along major surfaces thereof clamped between two stainless steel backing plates. The conductor plate is provided with a plurality of contact buttons affixed therein in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors.

  4. Extreme Events: low and high total ozone over Arosa, Switzerland

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Staehelin, J.; Maeder, J. A.; Ribatet, M.; Stübi, R.; Weihs, P.; Holawe, F.; Peter, T.; Davison, A. C.

    2009-04-01

    The frequency distribution of days with extreme low (termed ELOs) and high (termed EHOs) total ozone is analyzed for the world's longest total ozone record (Arosa, Switzerland - for details see Staehelin et al.,1998a,b), with new tools from extreme value theory (e.g. Coles, 2001; Ribatet, 2007). A heavy-tail focused approach is used through the fitting of the Generalized Pareto Distribution (GPD) to the Arosa time series. Asymptotic arguments (Pickands, 1975) justify the use of the GPD for modeling exceedances over a high (or below a low) enough threshold (Coles, 2001). The analysis shows that the GPD is appropriate for modeling the frequency distribution in total ozone above or below a mathematically well-defined threshold. While previous studies focused on so termed ozone mini-holes and mini-highs (e.g. Bojkov and Balis, 2001, Koch et al., 2005), this study is the first to present a mathematical description of extreme events in low and high total ozone for a northern mid-latitudes site (Rieder et al., 2009). The results show (a) an increase in days with extreme low (ELOs) and (b) a decrease in days with extreme high total ozone (EHOs) during the last decades, (c) that the general trend in total ozone is strongly determined by these extreme events and (d) that fitting the GPD is an appropriate method for the estimation of the frequency distribution of so-called ozone mini-holes. Furthermore, this concept allows one to separate the effect of Arctic ozone depletion from that of in situ mid-latitude ozone loss. As shown by this study, ELOs and EHOs have a strong influence on mean values in total ozone and the "extremes concept" could be further used also for validation of Chemistry-Climate-Models (CCMs) within the scientific community. References: Bojkov, R. D., and Balis, D.S.: Characteristics of episodes with extremely low ozone values in the northern middle latitudes 1975-2000, Ann. Geophys., 19, 797-807, 2001. Coles, S.: An Introduction to Statistical Modeling of

  5. Is Extremely High Life Satisfaction during Adolescence Advantageous?

    ERIC Educational Resources Information Center

    Suldo, Shannon M.; Huebner, E. Scott

    2006-01-01

    This study examined whether extremely high life satisfaction was associated with adaptive functioning or maladaptive functioning. Six hundred ninety-eight secondary level students completed the Students' Life Satisfaction Scale [Huebner, 1991a, School Psychology International, 12, pp. 231-240], Youth Self-Report of the Child Behavior Checklist…

  6. Extreme high-head portables provide more pumping options

    SciTech Connect

    Fiscor, S.

    2006-10-15

    Three years ago, Godwin Pumps, one of the largest manufacturers of portable pumps, introduced its Extreme Duty High Lift (HL) series of pumps and more mines are finding unique applications for these pumps. The Extreme HL series is a range single-stage Dri-Prime pumps with heads up to 600 feet and flows up to 5,000 gallons per minute. The American Coal Co.'s Galatia mine, an underground longwall mine in southern Illinois, used an HL 160 to replace a multiple-staged centrifugal pump. It provided Galatia with 1,500 gpm at 465 ft. 3 photos.

  7. Extreme ultraviolet high-harmonic spectroscopy of solids

    NASA Astrophysics Data System (ADS)

    Luu, T. T.; Garg, M.; Kruchinin, S. Yu.; Moulet, A.; Hassan, M. Th.; Goulielmakis, E.

    2015-05-01

    Extreme ultraviolet (EUV) high-harmonic radiation emerging from laser-driven atoms, molecules or plasmas underlies powerful attosecond spectroscopy techniques and provides insight into fundamental structural and dynamic properties of matter. The advancement of these spectroscopy techniques to study strong-field electron dynamics in condensed matter calls for the generation and manipulation of EUV radiation in bulk solids, but this capability has remained beyond the reach of optical sciences. Recent experiments and theoretical predictions paved the way to strong-field physics in solids by demonstrating the generation and optical control of deep ultraviolet radiation in bulk semiconductors, driven by femtosecond mid-infrared fields or the coherent up-conversion of terahertz fields to multi-octave spectra in the mid-infrared and optical frequencies. Here we demonstrate that thin films of SiO2 exposed to intense, few-cycle to sub-cycle pulses give rise to wideband coherent EUV radiation extending in energy to about 40 electronvolts. Our study indicates the association of the emitted EUV radiation with intraband currents of multi-petahertz frequency, induced in the lowest conduction band of SiO2. To demonstrate the applicability of high-harmonic spectroscopy to solids, we exploit the EUV spectra to gain access to fine details of the energy dispersion profile of the conduction band that are as yet inaccessible by photoemission spectroscopy in wide-bandgap dielectrics. In addition, we use the EUV spectra to trace the attosecond control of the intraband electron motion induced by synthesized optical transients. Our work advances lightwave electronics in condensed matter into the realm of multi-petahertz frequencies and their attosecond control, and marks the advent of solid-state EUV photonics.

  8. High resolution modelling of extreme precipitation events in urban areas

    NASA Astrophysics Data System (ADS)

    Siemerink, Martijn; Volp, Nicolette; Schuurmans, Wytze; Deckers, Dave

    2015-04-01

    The present day society needs to adjust to the effects of climate change. More extreme weather conditions are expected, which can lead to longer periods of drought, but also to more extreme precipitation events. Urban water systems are not designed for such extreme events. Most sewer systems are not able to drain the excessive storm water, causing urban flooding. This leads to high economic damage. In order to take appropriate measures against extreme urban storms, detailed knowledge about the behaviour of the urban water system above and below the streets is required. To investigate the behaviour of urban water systems during extreme precipitation events new assessment tools are necessary. These tools should provide a detailed and integral description of the flow in the full domain of overland runoff, sewer flow, surface water flow and groundwater flow. We developed a new assessment tool, called 3Di, which provides detailed insight in the urban water system. This tool is based on a new numerical methodology that can accurately deal with the interaction between overland runoff, sewer flow and surface water flow. A one-dimensional model for the sewer system and open channel flow is fully coupled to a two-dimensional depth-averaged model that simulates the overland flow. The tool uses a subgrid-based approach in order to take high resolution information of the sewer system and of the terrain into account [1, 2]. The combination of using the high resolution information and the subgrid based approach results in an accurate and efficient modelling tool. It is now possible to simulate entire urban water systems using extreme high resolution (0.5m x 0.5m) terrain data in combination with a detailed sewer and surface water network representation. The new tool has been tested in several Dutch cities, such as Rotterdam, Amsterdam and The Hague. We will present the results of an extreme precipitation event in the city of Schiedam (The Netherlands). This city deals with

  9. Comparative Analysis of Stormtime Ring Currents Under Extreme Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Liemohn, M. W.; Thomsen, M. F.; Borovsky, J. E.; Hairston, M. R.; Ridley, A. J.

    2001-12-01

    Several recent magnetic superstorms (6 April 2000, 15 July 2000 and 31 March 2001) are numerically and observationally analyzed to understand the response of the ring current to extreme values of southward IMF Bz. Simulations of these events were carried out using the Michigan ring current drift-loss model (RAM) driven by dynamical fluxes at the nightside outer boundary based on observations. Plasma sheet distributions measured by satellites were used to specify the ring current source population and its variation during the events. Plasma sheet densities were elevated for all three events but reached their most extreme value (near 10 cm-3) during the March 2001 superstorm which also had the largest ěrtminimum Dst*ěrt. Convection electric fields within the inner magnetosphere were specified based on the McIlwain (1986) model scaled by the polar-cap potential (PCP) derived from DMSP observations. Shielding in the McIlwain model was parametrized based on the DMSP auroral boundary index (MBI). Maximum values of the DMSP PCP were < 250 kV for July 2000 and March 2001 compared to peak values near 600 kV predicted by linear parametrizations based on more moderate storms. It is clear that the relationship between the PCP and solar wind Ey changes dramatically during extreme events and this will have a major impact on ring current energization. We examine the relationship between convection strength (polar cap potential), ion source intensity (near-Earth plasma sheet flux), and ion source composition (H+ versus O+) to understand ring current dynamics and evolution during each of these events. Finally, we compare the differences and similarities in the magnetospheric responses to the three selected intervals of extreme solar wind conditions.

  10. High current gain transistor laser.

    PubMed

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  11. High current gain transistor laser

    NASA Astrophysics Data System (ADS)

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  12. High current gain transistor laser

    PubMed Central

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  13. Method for synthesizing extremely high-temperature melting materials

    SciTech Connect

    Saboungi, Marie-Louise; Glorieux, Benoit

    2007-11-06

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as carbides and transition-metal, lanthanide and actinide oxides, using an aerodynamic levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  14. Method For Synthesizing Extremely High-Temperature Melting Materials

    SciTech Connect

    Saboungi, Marie-Louise; Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  15. High critical current superconducting tapes

    DOEpatents

    Holesinger, Terry G.; Jia, Quanxi; Foltyn, Stephen R.

    2003-09-23

    Improvements in critical current capacity for superconducting film structures are disclosed and include the use of a superconducting RE-BCO layer including a mixture of rare earth metals, e.g., yttrium and europium, where the ratio of yttrium to europium in the RE-BCO layer ranges from about 3 to 1 to from about 1.5 to 1.

  16. Characteristics of extreme ultraviolet emission from high-Z plasmas

    NASA Astrophysics Data System (ADS)

    Ohashi, H.; Higashiguchi, T.; Suzuki, Y.; Kawasaki, M.; Suzuki, C.; Tomita, K.; Nishikino, M.; Fujioka, S.; Endo, A.; Li, B.; Otsuka, T.; Dunne, P.; O'Sullivan, G.

    2016-03-01

    We demonstrate the extreme ultraviolet (EUV) and soft x-ray sources in the 2 to 7 nm spectral region related to the beyond EUV (BEUV) question at 6.x nm and the water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs), extending below the carbon K edge (4.37 nm). An outline of a microscope design for single-shot live cell imaging is proposed based on high-Z plasma UTA source, coupled to multilayer mirror optics.

  17. Current and future U.S. weather extremes and El Niño

    NASA Astrophysics Data System (ADS)

    Meehl, Gerald A.; Tebaldi, Claudia; Teng, Haiyan; Peterson, Thomas C.

    2007-10-01

    A global coupled climate model representative of the current generation of models is shown to simulate most first order aspects of El Niño events, their teleconnections over North America, and the associated observed patterns of extremes in present-day climate. Future El Niño teleconnection patterns over the U.S. are projected to shift eastward and northward due in part to the different midlatitude base state atmospheric circulation in a warmer climate. Consequently, projections for the changes in the patterns of extremes over the U.S. during future El Niño events include: decreases of frost days over the southwestern U.S expand northward and eastward; increases in intense precipitation in the SW U.S. expands eastward and areas in the SE U.S. become stronger; and decreases of heat wave intensity over much of the southern tier of states turn to increases.

  18. Solidification at the High and Low Rate Extreme

    SciTech Connect

    Halim Meco

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  19. ELECTROMIGRATION ISSUES IN HIGH CURRENT HORN.

    SciTech Connect

    ZHANG, S.Y.; BELLAVIA, S.; SANDBERG, J.; ET AL.

    2005-05-16

    The secondary particle focusing horn for the AGS neutrino experiment proposal is a high current and high current density device. The peak current of horn is 300 kA. At the smallest area of horn, the current density is near 8 kA/mm{sup 2}. At very high current density, a few kA/mm{sup 2}, the electromigration phenomena will occur. Momentum transfer between electrons and metal atoms at high current density causes electromigration. The reliability and lifetime of focusing horn can be severely reduced by electromigration. In this paper, we discuss issues such as device reliability model, incubation time of electromigration, and lifetime of horn.

  20. High-resolution stochastic generation of extreme rainfall intensity for urban drainage modelling applications

    NASA Astrophysics Data System (ADS)

    Peleg, Nadav; Blumensaat, Frank; Molnar, Peter; Fatichi, Simone; Burlando, Paolo

    2016-04-01

    Urban drainage response is highly dependent on the spatial and temporal structure of rainfall. Therefore, measuring and simulating rainfall at a high spatial and temporal resolution is a fundamental step to fully assess urban drainage system reliability and related uncertainties. This is even more relevant when considering extreme rainfall events. However, the current space-time rainfall models have limitations in capturing extreme rainfall intensity statistics for short durations. Here, we use the STREAP (Space-Time Realizations of Areal Precipitation) model, which is a novel stochastic rainfall generator for simulating high-resolution rainfall fields that preserve the spatio-temporal structure of rainfall and its statistical characteristics. The model enables a generation of rain fields at 102 m and minute scales in a fast and computer-efficient way matching the requirements for hydrological analysis of urban drainage systems. The STREAP model was applied successfully in the past to generate high-resolution extreme rainfall intensities over a small domain. A sub-catchment in the city of Luzern (Switzerland) was chosen as a case study to: (i) evaluate the ability of STREAP to disaggregate extreme rainfall intensities for urban drainage applications; (ii) assessing the role of stochastic climate variability of rainfall in flow response and (iii) evaluate the degree of non-linearity between extreme rainfall intensity and system response (i.e. flow) for a small urban catchment. The channel flow at the catchment outlet is simulated by means of a calibrated hydrodynamic sewer model.

  1. High temperature superconductor current leads

    DOEpatents

    Hull, J.R.; Poeppel, R.B.

    1995-06-20

    An electrical lead is disclosed having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths. 9 figs.

  2. High temperature superconductor current leads

    DOEpatents

    Hull, John R.; Poeppel, Roger B.

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  3. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements

    NASA Astrophysics Data System (ADS)

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6Hzto1.4MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems.

  4. Studying and applying channeling at extremely high bunch charges

    SciTech Connect

    Carrigan, R.A.; /Fermilab

    2005-01-01

    The potentially high plasma densities possible in solids might produce extremely high acceleration gradients. However solid-state plasmas could pose daunting challenges. Crystal channeling has been suggested as a mechanism to ameliorate these problems. A high-density plasma in a crystal lattice could quench the channeling process. There is no experimental or theoretical guidance on channeling for intense charged particle beams. An experiment has been carried out at the Fermilab A0 photoinjector to observe electron channeling radiation at high bunch charges. An electron beam with up to 8 nC per electron bunch was used to investigate the electron-crystal interaction. No evidence was found of quenching of channeling at charge densities two orders of magnitude larger than in earlier experiments. Possible new channeling experiments are discussed for the much higher bunch charge densities and shorter times required to probe channeling breakdown and plasma behavior.

  5. High numerical aperture projection system for extreme ultraviolet projection lithography

    DOEpatents

    Hudyma, Russell M.

    2000-01-01

    An optical system is described that is compatible with extreme ultraviolet radiation and comprises five reflective elements for projecting a mask image onto a substrate. The five optical elements are characterized in order from object to image as concave, convex, concave, convex, and concave mirrors. The optical system is particularly suited for ring field, step and scan lithography methods. The invention uses aspheric mirrors to minimize static distortion and balance the static distortion across the ring field width which effectively minimizes dynamic distortion. The present invention allows for higher device density because the optical system has improved resolution that results from the high numerical aperture, which is at least 0.14.

  6. Pregnancy and Beyond Part II: Temperature Extremes and High Altitude

    PubMed Central

    Borkenhagen, Rainer H.

    1988-01-01

    Over the last 35 years, transport technology has created new environmental frontiers in which family physicians are, and will continue to be, involved both in research and in administering patient care. Some frontiers address basic physiological problems that cross over into others. In a series of four articles, the author describes six of these frontiers with specific emphasis on pregnancy, from hyperbarism (undersea physiology) to microgravity (space physiology), and the problems, and linkages where evident. This second article explores the effects of temperature extremes and high altitude on the well-being of pregnant women. PMID:21253103

  7. High temperature superconducting fault current limiter

    DOEpatents

    Hull, J.R.

    1997-02-04

    A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

  8. High temperature superconducting fault current limiter

    DOEpatents

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  9. Relative importance of ring and tail currents to Dst under extremely disturbed conditions

    NASA Astrophysics Data System (ADS)

    Kalegaev, V. V.; Makarenkov, E. V.

    2008-02-01

    Relative ring current (RC) and tail current (TC) contributions to Dst were investigated on the basis of the statistical study of 70 magnetic storms of different intensities. Special attention was paid to the extremely disturbed conditions during magnetic storms in October-November 2003. Variations of the magnetic field produced by magnetospheric currents on the Earth's surface were calculated using paraboloid model of the magnetosphere A2000 [Alexeev, I.I., Belenkaya, E.S., Kalegaev, V.V., Feldstein, Y.I., Grafe, A., 1996. Journal of Geophysical Research 101,7737; Alexeev, I.I., Kalegaev, V.V., Belenkaya, E.S., Bobrovnikov, S.Yu., Feldstein, Ya.I., Gromova, L.I., 2001. Journal of Geophysical Research 106, 25683], taking into account the effect of terrestrial induced currents. For each magnetic storm we calculated Dst and contributions produced by large-scale magnetospheric current systems. The relative RC and TC contributions for each event at the storm maximum were examined in relationship to the peak pressure-corrected Dst value. Analysis of Dst sources confirms the conclusions of Kalegaev and Ganushkina [2005. In: Pulkkinen, T., Tsyganenko, N.A., Friedel, R.H.W. (Eds.), Physics and Modeling of the Inner Magnetosphere, AGU Geophysical Monograph 155. AGU, Washington, DC, p. 293] and Kalegaev and Makarenkov [2006. Geomagnetism and Aeronomy 46, 570] about saturation of the TC effect under extremely disturbed conditions. The RC becomes the dominant Dst source during severe magnetic storms, but during moderate storms its contribution to Dst is comparable with TC's contribution. The RC injection amplitude increases with the growth of magnetospheric disturbance level.

  10. Apparatus for measuring high frequency currents

    NASA Technical Reports Server (NTRS)

    Hagmann, Mark J. (Inventor); Sutton, John F. (Inventor)

    2003-01-01

    An apparatus for measuring high frequency currents includes a non-ferrous core current probe that is coupled to a wide-band transimpedance amplifier. The current probe has a secondary winding with a winding resistance that is substantially smaller than the reactance of the winding. The sensitivity of the current probe is substantially flat over a wide band of frequencies. The apparatus is particularly useful for measuring exposure of humans to radio frequency currents.

  11. Numerical study of induced current perturbations in the vicinity of excitable cells exposed to extremely low frequency magnetic fields

    NASA Astrophysics Data System (ADS)

    Hassan, Noha; Chatterjee, Indira; Publicover, Nelson G.; Craviso, Gale L.

    2003-10-01

    Realistic three-dimensional cell morphologies were modelled to determine the current density induced in excitable cell culture preparations exposed to 60 Hz magnetic fields and to identify important factors that can influence the responses of cells to these fields. Cell morphologies representing single spherical adrenal chromaffin cells, single elongated smooth muscle cells and chromaffin cell aggregates in a Petri dish containing culture medium were modelled using the finite element method. The computations for a spherical cell revealed alterations in the magnitude and spatial distribution of the induced current density in the immediate vicinity of the cell. Maxima occurred at the equatorial sides and minima at the poles. Proximity of cells to each other as well as cell aggregate shape, size and orientation with respect to the induced current influenced the magnitude and spatial distribution of the induced current density. For an elongated cell, effects on the induced current density were highly dependent on cell orientation with respect to the direction of the induced current. These results provide novel insights into the perturbations in induced current that occur in excitable cell culture preparations and lay a foundation for understanding the mechanisms of interaction with extremely low frequency magnetic fields at the tissue level.

  12. High Temperature Polyimide Materials in Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; Gates, Thomas S.

    2001-01-01

    At the end of the NASA High Speed Research (HSR) Program, NASA Langley Research Center (LaRC) began a program to screen the high-temperature Polymeric Composite Materials (PMCs) characterized by the HSR Durability Program for possible use in Reusable Launch Vehicles (RLVs) operating under extreme temperature conditions. The HSR Program focused on developing material-related technologies to enable a High Speed Civil Transport (HSCT) capable of operating temperatures ranging from 54 C (-65 F) to 177 C (350 F). A high-temperature polymeric resin, PETI-5 was used in the HSR Program to satisfy the requirements for performance and durability for a PMC. For RLVs, it was anticipated that this high temperature material would contribute to reducing the overall weight of a vehicle by eliminating or reducing the thermal protection required to protect the internal structural elements of the vehicle and increasing the structural strain limits. The tests were performed to determine temperature-dependent mechanical and physical proper-ties of IM7/PETI-5 composite over a temperature range from cryogenic temperature -253 C (-423F) to the material's maximum use temperature of 230 C (450 F). This paper presents results from the test program for the temperature-dependent mechanical and physical properties of IM7/PETI-5 composite in the temperature range from -253 C (-423 F) to 27 C (80 F).

  13. Ptychographic hyperspectral spectromicroscopy with an extreme ultraviolet high harmonic comb.

    PubMed

    Zhang, Bosheng; Gardner, Dennis F; Seaberg, Matthew H; Shanblatt, Elisabeth R; Porter, Christina L; Karl, Robert; Mancuso, Christopher A; Kapteyn, Henry C; Murnane, Margaret M; Adams, Daniel E

    2016-08-01

    We report a proof-of-principle demonstration of a new scheme of spectromicroscopy in the extreme ultraviolet (EUV) spectral range, where the spectral response of the sample at different wavelengths is imaged simultaneously. This scheme is enabled by combining ptychographic information multiplexing (PIM) with a tabletop EUV source based on high harmonic generation, where four spectrally narrow harmonics near 30 nm form a spectral comb structure. Extending PIM from previously demonstrated visible wavelengths to the EUV/X-ray wavelengths promises much higher spatial resolution and a more powerful spectral contrast mechanism, making PIM an attractive spectromicroscopy method in both microscopy and spectroscopy aspects. In addition to spectromicroscopy, this method images the multicolor EUV beam in situ, making this a powerful beam characterization technique. In contrast to other methods, the techniques described here use no hardware to separate wavelengths, leading to efficient use of the EUV radiation. PMID:27505837

  14. Extreme ultraviolet spectra of highly ionized oxygen and fluorine

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Griffin, P. M.; Haselton, H. H.; Laubert, R.; Mowat, J. R.; Thoe, R. S.; Peterson, R. S.; Sellin, I. A.

    1974-01-01

    The foil-excitation method has been used to study the extreme ultraviolet spectra of highly ionized oxygen and fluorine. Several previously unreported lines in heliumlike fluorine are reported and other newly reported lines in heliumlike oxygen have been measured to higher accuracy. Included in the measurements are certain heliumlike oxygen transitions of significance in interpretation of solar-flare spectral observations. The wavelength determinations are usually in good agreement with calculated results which includes relativistic corrections, but discrepancies arise when nonrelativistic calculations are used. A comparison of the present results and those recently obtained by theta-pinch and laser-induced plasma sources is made for both heliumlike and lithiumlike ions; a few discrepancies occur, with results in most cases in better agreement with relativistically corrected calculations. Certain unidentified lines in the spectra may be attributable to radiative transitions between quartet states of lithiumlike ions.

  15. Hybrid high direct current circuit interrupter

    DOEpatents

    Rockot, Joseph H.; Mikesell, Harvey E.; Jha, Kamal N.

    1998-01-01

    A device and a method for interrupting very high direct currents (greater than 100,000 amperes) and simultaneously blocking high voltages (greater than 600 volts). The device utilizes a mechanical switch to carry very high currents continuously with low loss and a silicon controlled rectifier (SCR) to bypass the current around the mechanical switch while its contacts are separating. A commutation circuit, connected in parallel with the SCR, turns off the SCR by utilizing a resonant circuit to divert the SCR current after the switch opens.

  16. Hybrid high direct current circuit interrupter

    DOEpatents

    Rockot, J.H.; Mikesell, H.E.; Jha, K.N.

    1998-08-11

    A device and a method are disclosed for interrupting very high direct currents (greater than 100,000 amperes) and simultaneously blocking high voltages (greater than 600 volts). The device utilizes a mechanical switch to carry very high currents continuously with low loss and a silicon controlled rectifier (SCR) to bypass the current around the mechanical switch while its contacts are separating. A commutation circuit, connected in parallel with the SCR, turns off the SCR by utilizing a resonant circuit to divert the SCR current after the switch opens. 7 figs.

  17. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.

    PubMed

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6 Hz to 1.4 MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems. PMID:17902966

  18. Proton delocalization under extreme conditions of high pressure and temperature

    SciTech Connect

    Goncharov, Alexander F.; Crowhurst, Jonathan

    2008-10-02

    Knowledge of the behaviour of light hydrogen-containing molecules under extreme conditions of high pressure and temperature is crucial to a comprehensive understanding of the fundamental physics and chemistry that is relevant under such conditions. It is also vital for interpreting the results of planetary observations, in particular those of the gas giants, and also for various materials science applications. On a fundamental level, increasing pressure causes the redistribution of the electronic density, which results in a modification of the interatomic potentials followed by a consequent qualitative change in the character of the associated bonding. Ultimately, at sufficiently high pressure, one may anticipate a transformation to a homogeneously bonded material possessing unusual physical properties (e.g. a quantum fluid). As temperature increases so does the concentration of ionised species leading ultimately to a plasma. Considerable improvements have recently been made in both the corresponding experimental and theoretical investigations. Here we review recent results for hydrogen and water that reveal unexpected routes of transformation to nonmolecular materials. We stress the importance of quantum effects, which remain significant even at high temperatures.

  19. Nitrogen Accumulation and Partitioning in High Arctic Tundra from Extreme Atmospheric N Deposition Events

    NASA Astrophysics Data System (ADS)

    Phoenix, G. K.; Osborn, A.; Blaud, A.; Press, M. C.; Choudhary, S.

    2013-12-01

    Arctic ecosystems are threatened by pollution from extreme atmospheric nitrogen (N) deposition events. These events occur from the long-range transport of reactive N from pollution sources at lower latitudes and can deposit up to 80% of the annual N deposition in just a few days. To date, the fate and impacts of these extreme pollutant events has remained unknown. Using a field simulation study, we undertook the first assessment of the fate of acutely deposited N on arctic tundra. Extreme N deposition events were simulated on field plots at Ny-Ålesund, Svalbard (79oN) at rates of 0, 0.04, 0.4 and 1.2 g N m-2 yr-1 applied as NH4NO3 solution over 4 days, with 15N tracers used in the second year to quantify the fate of the deposited N in the plant, soil, microbial and leachate pools. Separate applications of 15NO3- and 15NH4+ were also made to determine the importance of N form in the fate of N. Recovery of the 15N tracer at the end of the first growing season approached 100% of the 15N applied irrespective of treatment level, demonstrating the considerable capacity of High Arctic tundra to capture pollutant N from extreme deposition events. Most incorporation of the 15N was found in bryophytes, followed by the dominant vascular plant (Salix polaris) and the microbial biomass of the soil organic layer. Total recovery remained high in the second growing season (average of 90%), indicating highly conservative N retention. Between the two N forms, recovery of 15NO3- and 15NH4+ were equal in the non-vascular plants, whereas in the vascular plants (particularly Salix polaris) recovery of 15NO3- was four times higher than of 15NH4+. Overall, these findings show that High Arctic tundra has considerable capacity to capture and retain the pollutant N deposited in acute extreme deposition events. Given they can represent much of the annual N deposition, extreme deposition events may be more important than increased chronic N deposition as a pollution source. Furthermore

  20. Extremely high-frequency micro-Doppler measurements of humans

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Silvious, Jerry L.; Dietlein, Charles R.; Green, Jeremy A.; Wikner, David A.

    2014-05-01

    The development of sensors that are capable of penetrating smoke, dust, fog, clouds, and rain is critical for maintaining situational awareness in degraded visual environments and for providing support to the Warfighter. Atmospheric penetration properties, the ability to form high-resolution imagery with modest apertures, and available source power make the extremely high-frequency (EHF) portion of the spectrum promising for the development of radio frequency (RF) sensors capable of penetrating visual obscurants. Comprehensive phenomenology studies including polarization and backscatter properties of relevant targets are lacking at these frequencies. The Army Research Laboratory (ARL) is developing a fully-polarimetric frequency-modulated continuous-wave (FMCW) instrumentation radar to explore polarization and backscatter properties of in-situ rain, scattering from natural and man-made surfaces, and the radar cross section and micro-Doppler signatures of humans at EHF frequencies, specifically, around the 220 GHz atmospheric window. This work presents an overview of the design and construction of the radar system, hardware performance, data acquisition software, and initial results including an analysis of human micro-Doppler signatures.

  1. Extreme-ultraviolet ultrafast ARPES at high repetition rates

    NASA Astrophysics Data System (ADS)

    Buss, Jan; Wang, He; Xu, Yiming; Stoll, Sebastian; Zeng, Lingkun; Ulonska, Stefan; Denlinger, Jonathan; Hussain, Zahid; Jozwiak, Chris; Lanzara, Alessandra; Kaindl, Robert

    Time- and angle-resolved photoemission spectroscopy (trARPES) represents a powerful approach to resolve the electronic structure and quasiparticle dynamics in complex materials, yet is often limited in either momentum space (incident photon energy), probe sensitivity (pulse repetition rate), or energy resolution. We demonstrate a novel table-top trARPES setup that combines a bright 50-kHz source of narrowband, extreme ultraviolet (XUV) pulses at 22.3 eV with UHV photoemission instrumentation to sensitively access dynamics for a large momentum space. The output of a high-power Ti:sapphire amplifier is split to provide the XUV probe and intense photoexcitation (up to mJ/cm2) . A vacuum beamline delivers spectral and flux characterization, differential pumping, as well as XUV beam steering and toroidal refocusing onto the sample with high incident flux of 3x1011 ph/s. Photoemission studies are carried out in a customized UHV chamber equipped with a hemispherical analyzer (R4000), six-axis sample cryostat, and side chambers for sample loading, storage and preparation. An ARPES energy resolution down to 70 meV with the direct XUV output is demonstrated. We will discuss initial applications of this setup including Fermi surface mapping and trARPES of complex materials.

  2. High current ion beam transport using solenoids

    SciTech Connect

    Hollinger, R.; Spaedtke, P.

    2008-02-15

    In the framework of the future project FAIR several upgrade programs and construction of new facilities are in progress such as the U{sup 4+} upgrade for the existing high current injector and the new 70 MeV proton injector. For both injectors solenoids in the low energy beam transport section are foreseen to inject the beam into the following rf accelerator. The paper presents beam quality measurements of high current ion beams behind a solenoid using a slit-grid emittance measurement device, viewing targets, and a pepper pot measurement device at the high current test bench at GSI.

  3. High pressure, high current, low inductance, high reliability sealed terminals

    DOEpatents

    Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

    2010-03-23

    The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

  4. AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

    NASA Astrophysics Data System (ADS)

    Yadav, Amit; Titkov, Ilya E.; Sokolovskii, Grigorii S.; Karpov, Sergey Y.; Dudelev, Vladislav V.; Soboleva, Ksenya K.; Strassburg, Martin; Pietzonka, Ines; Lugauer, Hans-Juergen; Rafailov, Edik U.

    2016-03-01

    Efficiency of commercial 620 nm AlGaInP Golden Dragon-cased high-power LEDs has been studied under extremely high pump current density up to 4.5 kA/cm2 and pulse duration from microsecond down to sub-nanosecond range. To understand the nature of LED efficiency decrease with current, pulse width variation is used. Analysis of the pulse-duration dependence of the LED efficiency and emission spectrum suggests the active region overheating to be the major factor controlling the LED efficiency reduction at CW and sub-microsecond pumping. The overheating can be effectively avoided by the use of sub-nanosecond current pulses. A direct correlation between the onset of the efficiency decrease and LED overheating is demonstrated.

  5. Organometallic carboxylate resists for extreme ultraviolet with high sensitivity

    NASA Astrophysics Data System (ADS)

    Passarelli, James; Murphy, Michael; Re, Ryan Del; Sortland, Miriam; Hotalen, Jodi; Dousharm, Levi; Fallica, Roberto; Ekinci, Yasin; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-10-01

    We have developed organometallic carboxylate compounds [RnM)] capable of acting as negative-tone extreme ultraviolet (EUV) resists. The most sensitive of these resists contain antimony, three R-groups and two carboxylate groups, and carboxylate groups with polymerizable olefins (e.g., acrylate, methacrylate, or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of the molecules of the type RnM) where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O2CR‧). The sensitivity of these resists was evaluated using Emax or dose to maximum resist thickness after exposure and development. We found that the greatest predictor of sensitivity of the RnSb) resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins versus the number of nonhydrogen atoms. Linear and log plots of Emax versus POL for a variety of molecules of the type R3Sb) lend insight into the behavior of these resists.

  6. Extremely high-dimensional feature selection via feature generating samplings.

    PubMed

    Li, Shutao; Wei, Dan

    2014-06-01

    To select informative features on extremely high-dimensional problems, in this paper, a sampling scheme is proposed to enhance the efficiency of recently developed feature generating machines (FGMs). Note that in FGMs O(mlogr) time complexity should be taken to order the features by their scores; the entire computational cost of feature ordering will become unbearable when m is very large, for example, m > 10(11) , where m is the feature dimensionality and r is the size of the selected feature subset. To solve this problem, in this paper, we propose a feature generating sampling method, which can reduce this computational complexity to O(Gslog(G)+G(G+log(G))) while preserving the most informative features in a feature buffer, where Gs is the maximum number of nonzero features for each instance and G is the buffer size. Moreover, we show that our proposed sampling scheme can be deemed as the birth-death process based on random processes theory, which guarantees to include most of the informative features for feature selections. Empirical studies on real-world datasets show the effectiveness of the proposed sampling method. PMID:23864272

  7. Scour Caused by Extreme Waves and Currents near Offshore Gravitational Platforms

    NASA Astrophysics Data System (ADS)

    Shchemelinin, Leonid; Belyaev, Nikolay; Lebedev, Vladimir; Nudner, Igor; Semenov, Konstantin; Pelinovsky, Efim; Maximov, Vasily

    2014-05-01

    A soil scour problem is very important by operation of the gravity based structures (GBS). Strong scour may lead to loss of stability of the structure and cause technological disaster. In connection with this, it is necessary to assess and minimize the possibility of scour. Here we present the results of physical modeling of bed scour near the GBS with flat bottoms, close to the square and rectangular. The results of measurements of the bottom deformation caused by extreme waves and currents are given. The experiments were conducted in enclosure of model basin (40 x 6.2 m), within the work area (12x 6.2 m) with the model bottom and GBS. The work area was a broad crested weir. The bottom was formed by fine sand with a mean particle diameter of 0.22 mm. The wind waves were created by portable beam-type wave maker (the length of the beam was 6.1 m) mounted on the bottom of the basin. The modeling of the current was performed using standard centrifugal pump through pipes and valves. The wave impact was carried out using a single stationary vacuum wavemaker. The soil scour modeling was performed according to Froude number in the self-similar area of the Reynolds numbers. The modeling scale was 1:60. The optical measurements system of the surfaces (OMSS) was used to evaluate the bed deformation. The 3-D maps of the bottom after the end of the tests and drying of the model were given using the OMSS. The contactless acoustic measurement system has been applied for measuring of the bottom change during the large-amplitude wave action on the GBS model at discrete points. The results are used for the preparation of recommendations for the protection against scour.

  8. A compact submicrosecond, high current generator

    NASA Astrophysics Data System (ADS)

    Kovalchuk, B. M.; Kharlov, A. V.; Zorin, V. B.; Zherlitsyn, A. A.

    2009-08-01

    Pulsed current generator was developed for experiments with current carrying pulsed plasma. Main parts of the generator are capacitor bank, low inductive current driving lines, and central load part. Generator consists of four identical sections, connected in parallel to one load. Capacitor bank is assembled from 24 capacitor blocks (100 kV, 80 nF), connected in parallel. It stores 9.6 kJ at 100 kV charging voltage. Each capacitor block incorporates a multigap spark switch, which is able to commute by six parallel channels. Switches operate in dry air at atmospheric pressure. The generator was tested with an inductive load and a liner load. At 17.5 nH inductive load and 100 kV of charging voltage it provides 650 kA of current amplitude with 390 ns rise time with 0.6 Ω damping resistors in discharge circuit of each capacitor block. The net generator inductance without a load was optimized to be as low as 15 nH, which results in extremely low impedance of the generator (˜0.08 Ω). It ensures effective energy coupling with a low impedance load such as Z pinch. The generator operates reliably without any adjustments in 70-100 kV range of charging voltage. Jitter in delay between output pulse and triggering pulse is less than 5 ns at 70-100 kV charging voltage. Operation and handling are very simple, because no oil or purified gases are required for the generator. The generator has dimensions 5.24×1.2×0.18 m3 and total weight about 1400 kg, thus manifesting itself as simple, robust, and cost effective apparatus.

  9. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events.

    PubMed

    Choudhary, Sonal; Blaud, Aimeric; Osborn, A Mark; Press, Malcolm C; Phoenix, Gareth K

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem (15)N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g Nm(-2)yr(-1), applied as (15)NH4(15)NO3 in Svalbard (79(°)N), during the summer. Separate applications of (15)NO3(-) and (15)NH4(+) were also made to determine the importance of N form in their retention. More than 95% of the total (15)N applied was recovered after one growing season (~90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants>vascular plants>organic soil>litter>mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of (15)N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater (15)NO3(-) than (15)NH4(+), suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events may represent a major source of eutrophication. PMID:26956177

  10. A New High-Current Proton Accelerator

    SciTech Connect

    Cleland, M. R.; Galloway, R. A.; DeSanto, L.; Jongen, Y.

    2009-03-10

    A high-current (>20 mA) dc proton accelerator is being developed for applications such as boron neutron capture therapy (BNCT) and the detection of explosive materials by nuclear resonance absorption (NRA) of gamma radiation. The high-voltage dc accelerator (adjustable between 1.4 and 2.8 MeV) will be a single-ended industrial Dynamitron registered system equipped with a compact high-current, microwave-driven proton source. A magnetic mass analyzer inserted between the ion source and the acceleration tube will select the protons and reject heavier ions. A sorption pump near the ion source will minimize the flow of neutral hydrogen gas into the acceleration tube. For BNCT, a lithium target for generating epithermal neutrons is being developed that will be capable of dissipating the high power (>40 kW) of the proton beam. For NRA, special targets will be used to generate gamma rays with suitable energies for exciting nuclides typically present in explosive materials. Proton accelerators with such high-current and high-power capabilities in this energy range have not been developed previously.

  11. A New High-Current Proton Accelerator

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Galloway, R. A.; DeSanto, L.; Jongen, Y.

    2009-03-01

    A high-current (>20 mA) dc proton accelerator is being developed for applications such as boron neutron capture therapy (BNCT) and the detection of explosive materials by nuclear resonance absorption (NRA) of gamma radiation. The high-voltage dc accelerator (adjustable between 1.4 and 2.8 MeV) will be a single-ended industrial Dynamitron® system equipped with a compact high-current, microwave-driven proton source. A magnetic mass analyzer inserted between the ion source and the acceleration tube will select the protons and reject heavier ions. A sorption pump near the ion source will minimize the flow of neutral hydrogen gas into the acceleration tube. For BNCT, a lithium target for generating epithermal neutrons is being developed that will be capable of dissipating the high power (>40 kW) of the proton beam. For NRA, special targets will be used to generate gamma rays with suitable energies for exciting nuclides typically present in explosive materials. Proton accelerators with such high-current and high-power capabilities in this energy range have not been developed previously.

  12. High Temperature Extremes - Will They Transform Structure of Avian Assemblages in the Desert Southwest?

    NASA Astrophysics Data System (ADS)

    Mutiibwa, D.; Albright, T. P.; Wolf, B. O.; Mckechnie, A. E.; Gerson, A. R.; Talbot, W. A.; Sadoti, G.; O'Neill, J.; Smith, E.

    2014-12-01

    Extreme weather events can alter ecosystem structure and function and have caused mass mortality events in animals. With climate change, high temperature extremes are increasing in frequency and magnitude. To better understand the consequences of climate change, scientists have frequently employed correlative models based on species occurrence records. However, these approaches may be of limited utility in the context of extremes, as these are often outside historical ranges and may involve strong non-linear responses. Here we describe work linking physiological response informed by experimental data to geospatial climate datasets in order to mechanistically model the dynamics of dehydration risk to dessert passerine birds. Specifically, we modeled and mapped the occurrence of current (1980-2013) high temperature extremes and evaporative water loss rates for eight species of passerine birds ranging in size from 6.5-75g in the US Southwest portion of their range. We then explored the implications of a 4° C warming scenario. Evaporative water loss (EWL) across a range of high temperatures was measured in heat-acclimated birds captured in the field. We used the North American Land Data Assimilation System 2 dataset to obtain hourly estimates of EWL with a 14-km spatial grain. Assuming lethal dehydration occurs when water loss reaches 15% of body weight, we then produced maps of total daily EWL and time to lethal dehydration based on both current data and future scenarios. We found that milder events capable of producing dehydration in passerine birds over four or more hours were not uncommon over the Southwest, but rapid dehydration conditions (<3 hours) were rare. Under the warming scenario, the frequency and extent of dehydration events expanded greatly, often affecting areas several times larger than in present-day climate. Dehydration risk was especially high among smaller bodied passerines due to their higher mass-specific rates of water loss. Even after

  13. Extreme light. An intense pursuit of fundamental high energy physics

    NASA Astrophysics Data System (ADS)

    Mourou, Gérard; Wheeler, Jonathan A.; Tajima, Toshiki

    2015-09-01

    By the compression of petawatt pulses to multi-exawatt, a new route for the generation of Schwinger intensities capable of producing highenergy radiation and particle beams with extremely short time structure down to the attosecond-zeptosecond regime is being presented. Far from the traditional laser investigation in the eV regime, this laser-based approach offers a new paradigm to investigate the structure of vacuum and applications to subatomic physics.

  14. The Current State of Head and Neck Injuries in Extreme Sports

    PubMed Central

    Sharma, Vinay K.; Rango, Juan; Connaughton, Alexander J.; Lombardo, Daniel J.; Sabesan, Vani J.

    2015-01-01

    Background: Since their conception during the mid-1970s, international participation in extreme sports has grown rapidly. The recent death of extreme snowmobiler Caleb Moore at the 2013 Winter X Games has demonstrated the serious risks associated with these sports. Purpose: To examine the incidence and prevalence of head and neck injuries (HNIs) in extreme sports. Study Design: Descriptive epidemiological study. Methods: The National Electronic Injury Surveillance System (NEISS) was used to acquire data from 7 sports (2000-2011) that were included in the Winter and Summer X Games. Data from the NEISS database were collected for each individual sport per year and type of HNI. Cumulative data for overall incidence and injuries over the entire 11-year period were calculated. National estimates were determined using NEISS-weighted calculations. Incidence rates were calculated for extreme sports using data from Outdoor Foundation Participation Reports. Results: Over 4 million injuries were reported between 2000 and 2011, of which 11.3% were HNIs. Of all HNIs, 83% were head injuries and 17% neck injuries. The 4 sports with the highest total incidence of HNI were skateboarding (129,600), snowboarding (97,527), skiing (83,313), and motocross (78,236). Severe HNI (cervical or skull fracture) accounted for 2.5% of extreme sports HNIs. Of these, skateboarding had the highest percentage of severe HNIs. Conclusion: The number of serious injuries suffered in extreme sports has increased as participation in the sports continues to grow. A greater awareness of the dangers associated with these sports offers an opportunity for sports medicine and orthopaedic physicians to advocate for safer equipment, improved on-site medical care, and further research regarding extreme sports injuries. PMID:26535369

  15. Extreme degree of ionization in homogenous micro-capillary plasma columns heated by ultrafast current pulses.

    PubMed

    Avaria, G; Grisham, M; Li, J; Tomasel, F G; Shlyaptsev, V N; Busquet, M; Woolston, M; Rocca, J J

    2015-03-01

    Homogeneous plasma columns with ionization levels typical of megaampere discharges are created by rapidly heating gas-filled 520-μm-diameter channels with nanosecond rise time current pulses of 40 kA. Current densities of up to 0.3  GA cm^{-2} greatly increase Joule heating with respect to conventional capillary discharge Z pinches, reaching unprecedented degrees of ionization for a high-Z plasma column heated by a current pulse of remarkably low amplitude. Dense xenon plasmas are ionized to Xe^{28+}, while xenon impurities in hydrogen discharges reach Xe^{30+}. The unique characteristics of these hot, ∼300:1 length-to-diameter aspect ratio plasmas allow the observation of unexpected spectroscopic phenomena. Axial spectra show the unusual dominance of the intercombination line over the resonance line of He-like Al by nearly an order of magnitude, caused by differences in opacities in the axial and radial directions. These plasma columns could enable the development of sub-10-nm x-ray lasers. PMID:25793819

  16. Extreme Degree of Ionization in Homogenous Micro-Capillary Plasma Columns Heated by Ultrafast Current Pulses

    NASA Astrophysics Data System (ADS)

    Avaria, G.; Grisham, M.; Li, J.; Tomasel, F. G.; Shlyaptsev, V. N.; Busquet, M.; Woolston, M.; Rocca, J. J.

    2015-03-01

    Homogeneous plasma columns with ionization levels typical of megaampere discharges are created by rapidly heating gas-filled 520 -μ m -diameter channels with nanosecond rise time current pulses of 40 kA. Current densities of up to 0.3 GA cm-2 greatly increase Joule heating with respect to conventional capillary discharge Z pinches, reaching unprecedented degrees of ionization for a high-Z plasma column heated by a current pulse of remarkably low amplitude. Dense xenon plasmas are ionized to Xe28 + , while xenon impurities in hydrogen discharges reach Xe30 + . The unique characteristics of these hot, ˜300 :1 length-to-diameter aspect ratio plasmas allow the observation of unexpected spectroscopic phenomena. Axial spectra show the unusual dominance of the intercombination line over the resonance line of He-like Al by nearly an order of magnitude, caused by differences in opacities in the axial and radial directions. These plasma columns could enable the development of sub-10-nm x-ray lasers.

  17. The Influence of Solar Extreme Ultraviolet Radiation on Ring Current Ion Composition: Polar and CRRES Observations

    NASA Astrophysics Data System (ADS)

    Roeder, J. L.; Fennell, J. F.; Pulkkinen, T. I.; Turner, N. E.; Grande, M.

    2001-05-01

    The ion composition observations by the Polar spacecraft from the last solar minimum to the present are compared to similar observations by CRRES in the previous cycle. The Magnetospheric Ion Composition Spectrometer (MICS) was onboard CRRES and is part of the Polar CAMMICE experiment. The MICS sensor provided mass and charge state composition data for the energetic (1-425 keV/q) ions including H+, He+, He++, and O+. The 5-minute average number densities for each species are computed by mapping the MICS fluxes down to the magnetic equator using the measured pitch angle distributions and integrating the equatorial spectrum over the energy range 1-200 keV/q. Approximately 3.5 years of the Polar mission in the rising part of the solar cycle are used for the database. The densities are analyzed statistically with the solar EUV index F10.7 and various geomagnetic indices such as Kp and Dst. The results are compared with a similar study of the ion composition in the energy range 0.9-15.9 keV/q measured by the GEOS 2 satellite during geomagnetically quiet periods [Young et al., 1982], and with the recent survey of the relative composition measured by Polar averaged over all times [Pulkkinen et al., 2000]. It is found that ion densities at L ~ 6-7 during relatively quiet intervals show correlations to the EUV and geomagnetic activity similar to the results of Young et al. [1992]. At lower L the correlation of the ion density with the EUV and activity levels increases substantially, due in part to the extremely low energetic ion densities during the quiet intervals of solar minimum. This may be interpreted as a combination of the solar cycle effects on 1) the ring current source population; and 2) the processes which transport the ions to lower L. The behavior of the ion composition during geomagnetic stormtime is also investigated by restricting the density database to those intervals with the Dst index below a threshold value. Paradoxically, the Polar data shows that the

  18. Reliability of High I/O High Density CCGA Interconnect Electronic Packages under Extreme Thermal Environment

    NASA Technical Reports Server (NTRS)

    Ramesham, Rajeshuni

    2012-01-01

    This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions. Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performances, compatibility with standard surface-mount packaging assembly processes, and so on. CCGA packages are used in space applications such as in logic and microprocessor functions, telecommunications, payload electronics, and flight avionics. As these packages tend to have less solder joint strain relief than leaded packages or more strain relief over lead-less chip carrier packages, the reliability of CCGA packages is very important for short-term and long-term deep space missions. We have employed high density CCGA 1152 and 1272 daisy chained electronic packages in this preliminary reliability study. Each package is divided into several daisy-chained sections. The physical dimensions of CCGA1152 package is 35 mm x 35 mm with a 34 x 34 array of columns with a 1 mm pitch. The dimension of the CCGA1272 package is 37.5 mm x 37.5 mm with a 36 x 36 array with a 1 mm pitch. The columns are made up of 80% Pb/20%Sn material. CCGA interconnect electronic package printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging techniques. The assembled CCGA boards were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space missions. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling. This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non

  19. Simultaneous radio and satellite optical measurements of high-altitude sprite current and lightning continuing current

    NASA Astrophysics Data System (ADS)

    Cummer, Steven A.; Frey, Harald U.; Mende, Stephen B.; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred B.; Fukunishi, Hiroshi; Takahashi, Yukihiro

    2006-10-01

    We report coordinated measurements of lightning and resulting sprites using ground-level magnetic field sensors (<0.1 Hz to 30 kHz bandwidth) and the ISUAL instrument on the FORMOSAT-2 satellite. These measurements demonstrate two distinct elements of the connection between the radio and optical emissions. First, the quasi-static magnetic field signature is tightly correlated with the low-altitude optical emissions from the lightning flash, indicating that this radio signature is produced by continuing lightning current. Second, in two events with strong postreturn stroke extremely low frequency (ELF) magnetic pulses, the optical emissions demonstrate that there are no observable intensifications of low-altitude optical emissions associated with those pulses. If they were produced by a lightning process, such as an M-component, the connection between optical emissions and current seen in the return stroke and the continuing current suggests they should be visible. However, as has been observed previously, the bright, high-altitude optical emissions associated with the sprite are simultaneous with the ELF pulse. This is strong evidence that these ELF pulses originate in high-altitude electric current in the sprite itself and are not produced by a low-altitude lightning process.

  20. An extremely high altitude plume seen at Mars morning terminator

    NASA Astrophysics Data System (ADS)

    Sanchez-Lavega, Agustin; Garcia-Muñoz, Antonio; Garcia-Melendo, Enrique; Perez-Hoyos, Santiago; Gomez-Forrellad, Josep M.; Pellier, Christophe; Delcroix, Marc; Lopez-Valverde, Miguel Angel; Gonzalez-Galindo, Francisco; Jaeschke, Wayne; Parker, Donald C.; Phillips, James H.; Peach, Damian

    2014-11-01

    We report the occurrence in March and April 2012 of two bright very high altitude plumes at the Martian terminator at 250 km or more above the surface, thus well into the ionosphere and bordering on the exosphere. They were located at about 195 deg West longitude and -45 deg latitude (at Terra Cimmeria) and lasted for about 10 days. The features showed day-to-day variability, and were seen at the morning terminator but not at the evening limb, which indicates rapid evolution in less than 10 hours and a cyclic behavior. Photometric measurements are used to explore two possible scenarios to explain their nature. If the phenomenon is due to suspended particles (dust, CO2 or H2O ice clouds) reflecting solar radiation, the mean size is about 0.1 microns with a nadir optical depth > 0.06. Alternatively, the plume could be auroral emission above a region with a strong magnetic anomaly and where aurora has previously been detected. Importantly, both explanations defy our current understanding of the Mars upper atmosphere.AcknowledgementsThis work was supported by the Spanish MINECO projects AYA2012-36666 with FEDER support, CONSOLIDER program ASTROMOL CSD2009-00038 and AYA2011-30613-CO2-1. Grupos Gobierno Vasco IT765-13 and UPV/EHU UFI11/55.

  1. Identification of Extremely Premature Infants at High Risk of Rehospitalization

    PubMed Central

    Carlo, Waldemar A.; McDonald, Scott A.; Yao, Qing; Das, Abhik; Higgins, Rosemary D.

    2011-01-01

    OBJECTIVE: Extremely low birth weight infants often require rehospitalization during infancy. Our objective was to identify at the time of discharge which extremely low birth weight infants are at higher risk for rehospitalization. METHODS: Data from extremely low birth weight infants in Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network centers from 2002–2005 were analyzed. The primary outcome was rehospitalization by the 18- to 22-month follow-up, and secondary outcome was rehospitalization for respiratory causes in the first year. Using variables and odds ratios identified by stepwise logistic regression, scoring systems were developed with scores proportional to odds ratios. Classification and regression-tree analysis was performed by recursive partitioning and automatic selection of optimal cutoff points of variables. RESULTS: A total of 3787 infants were evaluated (mean ± SD birth weight: 787 ± 136 g; gestational age: 26 ± 2 weeks; 48% male, 42% black). Forty-five percent of the infants were rehospitalized by 18 to 22 months; 14.7% were rehospitalized for respiratory causes in the first year. Both regression models (area under the curve: 0.63) and classification and regression-tree models (mean misclassification rate: 40%–42%) were moderately accurate. Predictors for the primary outcome by regression were shunt surgery for hydrocephalus, hospital stay of >120 days for pulmonary reasons, necrotizing enterocolitis stage II or higher or spontaneous gastrointestinal perforation, higher fraction of inspired oxygen at 36 weeks, and male gender. By classification and regression-tree analysis, infants with hospital stays of >120 days for pulmonary reasons had a 66% rehospitalization rate compared with 42% without such a stay. CONCLUSIONS: The scoring systems and classification and regression-tree analysis models identified infants at higher risk of rehospitalization and might assist planning for care after

  2. Current endovascular therapy for lower extremity peripheral arterial disease: indications, outcomes and modalities

    PubMed Central

    Yan, B P; Kiernan, T J; Lam, Y-Y; Yu, C-M

    2009-01-01

    Atherosclerosis of the lower extremities frequently leads to lifestyle-restricting claudication and can cause critical limb ischaemia (rest pain, non-healing ulcer, or gangrene). The prevalence of peripheral arterial disease (PAD) is rising in line with an ageing population. In the USA, PAD affects 8–10 million people (approximately 12% of the adult population). There is a strong association with concomitant coronary artery and cerebral vascular disease in these patients, which represents a significant cause of mortality and morbidity in patients with PAD. Disease affecting the lower extremity peripheral vessels is most aggressive in smokers and diabetics.

  3. Ring current development during high speed streams

    NASA Astrophysics Data System (ADS)

    Jordanova, V. K.; Matsui, H.; Puhl-Quinn, P. A.; Thomsen, M. F.; Mursula, K.; Holappa, L.

    2009-07-01

    Episodes of southward (Bz<0) interplanetary magnetic field (IMF) which lead to disturbed geomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We simulate ring current evolution during a HSS-driven storm that occurred during 24-26 October 2002 and compare its dynamics with a CME-driven storm of similar strength during 22-23 April 2001. We use our kinetic ring current-atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. Ring current evolution depends on the interplay of time-dependent inflow of plasma from the magnetotail, particle acceleration and loss (mainly due to charge exchange) along adiabatic drift paths, and outflow of plasma from the dayside magnetopause; all of these processes are incorporated in our model. We compare results from simulations using a newly developed, Cluster data based, University of New Hampshire inner magnetospheric electric field (UNH-IMEF) convection model with simulations using a Volland-Stern (V-S) type convection model. We find that, first, periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. Second, during the HSS-driven storm the convection potential from UNH-IMEF model is highly variable and causes sporadic shallow injections resulting in a weak ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ion injection penetrating to lower L shells and stronger ring current buildup. V-S model predicts larger ring current injection during both storms. Third, the RAM driven by either convection model underestimates the total ring current energy during the recovery phase of the HSS storm

  4. COMPILATION OF CURRENT HIGH ENERGY PHYSICS EXPERIMENTS

    SciTech Connect

    Wohl, C.G.; Kelly, R.L.; Armstrong, F.E.; Horne, C.P.; Hutchinson, M.S.; Rittenberg, A.; Trippe, T.G.; Yost, G.P.; Addis, L.; Ward, C.E.W.; Baggett, N.; Goldschmidt-Clermong, Y.; Joos, P.; Gelfand, N.; Oyanagi, Y.; Grudtsin, S.N.; Ryabov, Yu.G.

    1981-05-01

    This is the fourth edition of our compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about April 1981, and (2) had not completed taking of data by 1 January 1977. We emphasize that only approved experiments are included.

  5. Phthalocyanine dye as an extremely photostable and highly fluorescent near-infrared labeling reagent

    NASA Astrophysics Data System (ADS)

    Peng, Xinzhan; Draney, Daniel R.; Volcheck, William M.; Bashford, Gregory R.; Lamb, Donald T.; Grone, Daniel L.; Zhang, Yonghong; Johnson, Craig M.

    2006-02-01

    Current organic fluorophores used as labeling reagents for biomolecule conjugation have significant limitations in photostability. This compromises their performance in applications that require a photostable fluorescent reporting group. For example, in molecular imaging and single molecule microscopy, photostable fluorescent labels are important for observing and tracking individual molecular events over extended period of time. We report in this paper an extremely photostable and highly fluorescent phthalocyanine dye, IRDye TM 700DX, as a near-infrared fluorescence labeling reagent to conjugate with biomolecules. This novel water-soluble silicon phthalocyanine dye has an isomericly pure chemical structure. The dye is about 45 to 128 times more photostable than current near-IR fluorophores, e.g. Alexa Fluor"R"680, Cy TM 5.5, Cy TM 7 and IRDye TM 800CW dyes; and about 27 times more photostable than tetramethylrhodamine (TMR), one of the most photostable organic dyes. This dye also meets all the other stringent requirements as an ideal fluorophore for biomolecules labeling such as excellent water solubility, no aggregation in high ionic strength buffer, large extinction coefficient and high fluorescent quantum yield. Antibodies conjugated with IRDye TM 700DX at high D/P ratio exist as monomeric species in high ionic buffer and have bright fluorescence. The IRDye TM 700DX conjugated antibodies generate sensitive, highly specific detection with very low background in Western blot and cytoblot assays.

  6. Magnetic relaxation, current sheets, and structure formation in an extremely Tenuous fluid medium

    SciTech Connect

    Bajer, K.; Moffatt, H. K.

    2013-12-20

    The process of relaxation of a unidirectional magnetic field in a highly conducting tenuous fluid medium is considered. Null points of the field play a critical role in this process. During an initial stage of relaxation, variations in magnetic pressure are eliminated, and current sheets build up in the immediate neighborhood of null points. This initial phase is followed by a long diffusive phase of slow algebraic decay of the field, during which fluid is continuously sucked into the current sheets, leading to exponential growth of fluid density and concentration of mass around the null points, which show a tendency to cluster. Ultimately, this second phase of algebraic decay gives way to a final period of exponential decay of the field. The peaks of density at the null points survive as a fossil relic of the decay process. Numerical solution of the governing equations provides convincing confirmation of this three-stage scenario. Generalizations to two- and three-dimensional fields are briefly considered.

  7. A Robust High Current Density Electron Gun

    NASA Astrophysics Data System (ADS)

    Mako, F.; Peter, W.; Shiloh, J.; Len, L. K.

    1996-11-01

    Proof-of-principle experiments are proposed to validate a new concept for a robust, high-current density Pierce electron gun (RPG) for use in klystrons and high brightness electron sources for accelerators. This rugged, long-life electron gun avoids the difficulties associated with plasma cathodes, thermionic emitters, and field emission cathodes. The RPG concept employs the emission of secondary electrons in a transmission mode as opposed to the conventional mode of reflection, i.e., electrons exit from the back face of a thin negative electron affinity (NEA) material, and in the same direction as the incident beam. Current amplification through one stage of a NEA material could be over 50 times. The amplification is accomplished in one or more stages consisting of one primary emitter and one or more secondary emitters. The primary emitter is a low current density robust emitter (e.g., thoriated tungsten). The secondary emitters are thin NEA electrodes which emit secondary electrons in the same direction as the incident beam. Specific application is targeted for a klystron gun to be used by SLAC with a cold cathode at 30-40 amps/cm^2 output from the secondary emission stage, a ~2 μs pulse length, and ~200 pulses/second.

  8. Corrosion resistant pipe with extremely high impact resistance

    SciTech Connect

    Drake, S.

    1999-11-01

    The next generation of fiberglass pipe, which combines outstanding corrosion resistance to an extremely wide range of industrial chemicals with impact resistance more than 100 times better than existing fiberglass pipe, is introduced. This pipe is initially rated for operating pressures of 150 psi (10 Bar) at up to 225 F (107 C), and has corrosion resistance that generally is as good or better than traditional vinyl ester or epoxy resins. Its resistance to halogens such as chlorine and bromine is especially outstanding. These properties are achieved with the use of a new type of DUCTILE thermosetting resin. Included is a discussion of the resin system and data comparing the properties of this new piping system with traditional epoxy and vinyl ester piping.

  9. Versatile high current metal ion implantation facility

    SciTech Connect

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1991-06-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multi-cathode, broad beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion-charge state multiplicity, and with a beam current of up to several amperes peak pulsed and several tens of mA time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. 28 refs., 5 figs.

  10. Fast high-temperature superconductor switch for high current applications

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Li, Qiang

    2013-07-01

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity.

  11. HIGH CURRENT RADIO FREQUENCY ION SOURCE

    DOEpatents

    Abdelaziz, M.E.

    1963-04-01

    This patent relates to a high current radio frequency ion source. A cylindrical plasma container has a coil disposed around the exterior surface thereof along the longitudinal axis. Means are provided for the injection of an unionized gas into the container and for applying a radio frequency signal to the coil whereby a radio frequency field is generated within the container parallel to the longitudinal axis thereof to ionize the injected gas. Cathode and anode means are provided for extracting transverse to the radio frequency field from an area midway between the ends of the container along the longitudinal axis thereof the ions created by said radio frequency field. (AEC)

  12. Extremely short impulse eddy current system for titanium and inconel samples testing

    SciTech Connect

    Chady, T.; Frankowski, P.

    2011-06-23

    This paper presents a new system for eddy current testing. The system enables tests with very short current impulses. Therefore, the frequency spectrum of the excitation signal is very wide. In this paper, a study of eddy current differential transducer for testing titanium element is also presented.

  13. Desformylgramicidin: a model channel with an extremely high water permeability.

    PubMed Central

    Saparov, S M; Antonenko, Y N; Koeppe, R E; Pohl, P

    2000-01-01

    The water conductivity of desformylgramicidin exceeds the permeability of gramicidin A by two orders of magnitude. With respect to its single channel hydraulic permeability coefficient of 1.1.10(-12) cm(3) s(-1), desformylgramicidin may serve as a model for extremely permeable aquaporin water channel proteins (AQP4 and AQPZ). This osmotic permeability exceeds the conductivity that is predicted by the theory of single-file transport. It was derived from the concentration distributions of both pore-impermeable and -permeable cations that were simultaneously measured by double barreled microelectrodes in the immediate vicinity of a planar bilayer. From solvent drag experiments, approximately five water molecules were found to be transported by a single-file process along with one ion through the channel. The single channel proton, potassium, and sodium conductivities were determined to be equal to 17 pS (pH 2.5), 7 and 3 pS, respectively. Under any conditions, the desformyl-channel remains at least 10 times longer in its open state than gramicidin A. PMID:11053127

  14. High-current SRF cavity design

    NASA Astrophysics Data System (ADS)

    Meidlinger, D.; Grimm, T. L.; Hartung, W.

    2006-07-01

    For high current applications, it is desirable for the cavity shape to have a low longitudinal loss factor and to have a high beam-breakup threshold current. This paper briefly describes three different cavities designed for this purpose: a six-cell elliptical cavity for particles traveling at the speed of light, a two-cell elliptical cavity for subluminal particle speeds, and a single cell cavity which uses the TM012 mode for acceleration. SUPERFISH simulations predict the peak fields in both of the elliptical cavities will not exceed the TeSLA values by more than 10% but both will have 28.7% larger apertures. The elliptical designs assume the bunch frequency equals the accelerating mode frequency. The beam pipe radius is chosen so that the cutoff frequency is less than twice that of the accelerating mode. Hence all of the monopole and dipole higher-order modes (HOMs) that can be driven by the beam have low loaded Q values. This simplifies the problem of HOM damping. The TM012 cavity is predicted to have much higher peak fields than a π-mode elliptical cavity, but offers potential advantages from its simplified shape; it is essentially a circular waveguide with curved end plates. This basic shape results in easier fabrication and simplified tuning.

  15. Extremely high energy cosmic neutrinos and relic neutrinos

    SciTech Connect

    Quigg, Chris; /Fermilab /CERN

    2006-03-01

    I review the essentials of ultrahigh-energy neutrino interactions, show how neutral-current detection and flavor tagging can enhance the scientific potential of neutrino telescopes, and sketch new studies on neutrino encounters with dark matter relics and on gravitational lensing of neutrinos.

  16. Reliability of high I/O high density CCGA interconnect electronic packages under extreme thermal environments

    NASA Astrophysics Data System (ADS)

    Ramesham, Rajeshuni

    2012-03-01

    Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performances, compatibility with standard surfacemount packaging assembly processes, and so on. CCGA packages are used in space applications such as in logic and microprocessor functions, telecommunications, payload electronics, and flight avionics. As these packages tend to have less solder joint strain relief than leaded packages or more strain relief over lead-less chip carrier packages, the reliability of CCGA packages is very important for short-term and long-term deep space missions. We have employed high density CCGA 1152 and 1272 daisy chained electronic packages in this preliminary reliability study. Each package is divided into several daisy-chained sections. The physical dimensions of CCGA1152 package is 35 mm x 35 mm with a 34 x 34 array of columns with a 1 mm pitch. The dimension of the CCGA1272 package is 37.5 mm x 37.5 mm with a 36 x 36 array with a 1 mm pitch. The columns are made up of 80% Pb/20%Sn material. CCGA interconnect electronic package printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging techniques. The assembled CCGA boards were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space missions. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling. This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions.

  17. High Accuracy Temperature Measurements Using RTDs with Current Loop Conditioning

    NASA Technical Reports Server (NTRS)

    Hill, Gerald M.

    1997-01-01

    To measure temperatures with a greater degree of accuracy than is possible with thermocouples, RTDs (Resistive Temperature Detectors) are typically used. Calibration standards use specialized high precision RTD probes with accuracies approaching 0.001 F. These are extremely delicate devices, and far too costly to be used in test facility instrumentation. Less costly sensors which are designed for aeronautical wind tunnel testing are available and can be readily adapted to probes, rakes, and test rigs. With proper signal conditioning of the sensor, temperature accuracies of 0.1 F is obtainable. For reasons that will be explored in this paper, the Anderson current loop is the preferred method used for signal conditioning. This scheme has been used in NASA Lewis Research Center's 9 x 15 Low Speed Wind Tunnel, and is detailed.

  18. Resection and reconstruction of pelvic and extremity soft tissue sarcomas with major vascular involvement: Current concepts.

    PubMed

    McGoldrick, Niall P; Butler, Joseph S; Lavelle, Maire; Sheehan, Stephen; Dudeney, Sean; O'Toole, Gary C

    2016-05-18

    Soft tissue sarcoma accounts for approximately 1% of all cancers diagnosed annually in the United States. When these rare malignant mesodermal tumours arise in the pelvis and extremities, they may potentially encase or invade large calibre vascular structures. This presents a major challenge in terms of safe excision while also leaving acceptable surgical margins. In recent times, the trend has been towards limb salvage with vascular reconstruction in preference to amputation. Newer orthopaedic and vascular reconstructive techniques including both synthetic and autogenous graft reconstruction have made complex limb-salvage surgery feasible. Despite this, limb-salvage surgery with concomitant vascular reconstruction remains associated with higher rates of post-operative complications including infection and amputation. In this review we describe the initial presentation and investigation of patients presenting with soft tissue sarcomas in the pelvis and extremities, which involve vascular structures. We further discuss the key surgical reconstructive principles and techniques available for the management of these complex tumours, drawn from our institution's experience as a national tertiary referral sarcoma service. PMID:27190757

  19. Resection and reconstruction of pelvic and extremity soft tissue sarcomas with major vascular involvement: Current concepts

    PubMed Central

    McGoldrick, Niall P; Butler, Joseph S; Lavelle, Maire; Sheehan, Stephen; Dudeney, Sean; O'Toole, Gary C

    2016-01-01

    Soft tissue sarcoma accounts for approximately 1% of all cancers diagnosed annually in the United States. When these rare malignant mesodermal tumours arise in the pelvis and extremities, they may potentially encase or invade large calibre vascular structures. This presents a major challenge in terms of safe excision while also leaving acceptable surgical margins. In recent times, the trend has been towards limb salvage with vascular reconstruction in preference to amputation. Newer orthopaedic and vascular reconstructive techniques including both synthetic and autogenous graft reconstruction have made complex limb-salvage surgery feasible. Despite this, limb-salvage surgery with concomitant vascular reconstruction remains associated with higher rates of post-operative complications including infection and amputation. In this review we describe the initial presentation and investigation of patients presenting with soft tissue sarcomas in the pelvis and extremities, which involve vascular structures. We further discuss the key surgical reconstructive principles and techniques available for the management of these complex tumours, drawn from our institution’s experience as a national tertiary referral sarcoma service. PMID:27190757

  20. Cesium telluride cathodes for the next generation of high-average current high-brightness photoinjectors

    SciTech Connect

    Filippetto, D. Qian, H.; Sannibale, F.

    2015-07-27

    We report on the performances of a Cs{sub 2}Te photocathode under extreme conditions of high peak time-dependent accelerating fields, continuous wave operations, and MHz pulse extraction with up to 0.3 mA average current. The measurements, performed in a normal conducting cavity, show extended lifetime and robustness, elucidate the main mechanisms for cathode degradation, and set the required system vacuum performance for compatibility with the operations of a high average power X-ray free electron laser user facility, opening the doors to the next generation of MHz-scale ultrafast scientific instruments.

  1. Estimation of friction velocity from the wind-wave spectrum at extremely high wind speeds

    NASA Astrophysics Data System (ADS)

    Takagaki, N.; Komori, S.; Suzuki, N.

    2016-05-01

    The equilibrium range of wind-waves at normal and extremely high wind speeds was investigated experimentally using a high-speed wind-wave tank together with field measurements at normal wind speeds. Water level fluctuations at normal and extremely high wind speeds were measured with resistance-type wave gauges, and the wind-wave spectrum and significant phase velocity were calculated. The equilibrium range constant was estimated from the wind-wave spectrum and showed the strong relationship with inverse wave age at normal and extremely high wind speeds. Using the strong relation between the equilibrium range constant and inverse wave age, a new method for estimating the wind speed at 10-m height (U 10) and friction velocity (u*) was proposed. The results suggest that U 10 and u* can be estimated from wave measurements alone at extremely high wind speeds in oceans under tropical cyclones.

  2. Absolute intensity calibration of the Wendelstein 7-X high efficiency extreme ultraviolet overview spectrometer system

    NASA Astrophysics Data System (ADS)

    Greiche, Albert; Biel, Wolfgang; Marchuk, Oleksandr; Burhenn, Rainer

    2008-09-01

    The new high effiency extreme ultraviolet overview spectrometer (HEXOS) system for the stellarator Wendelstein 7-X is now mounted for testing and adjustment at the tokamak experiment for technology oriented research (TEXTOR). One part of the testing phase was the intensity calibration of the two double spectrometers which in total cover a spectral range from 2.5 to 160.0 nm with overlap. This work presents the current intensity calibration curves for HEXOS and describes the method of calibration. The calibration was implemented with calibrated lines of a hollow cathode light source and the branching ratio technique. The hollow cathode light source provides calibrated lines from 16 up to 147 nm. We could extend the calibrated region in the spectrometers down to 2.8 nm by using the branching line pairs emitted by an uncalibrated pinch extreme ultraviolet light source as well as emission lines from boron and carbon in TEXTOR plasmas. In total HEXOS is calibrated from 2.8 up to 147 nm, which covers most of the observable wavelength region. The approximate density of carbon in the range of the minor radius from 18 to 35 cm in a TEXTOR plasma determined by simulating calibrated vacuum ultraviolet emission lines with a transport code was 5.5×1017 m-3 which corresponds to a local carbon concentration of 2%.

  3. High Intensive Processes and Extreme States of Matter: Achievements and Problems

    SciTech Connect

    Simonenko, V. A.

    2006-08-03

    The paper briefly presents some main highlights of High Energy Density Physics (HEDP) achievements starting from its origin in the 1940s to the current time. A decisive role of high explosives (HE) is emphasized in studying high intensive processes and high energy density states of matter. Mechanisms of detonation and kinetics of energy release still remain acute in the HE studying. Research and scientific applications of nuclear explosions opened a new stage in HEDP development. They provided a million-fold increase of energy density if compared to that of high explosives. High intensive heat waves and strong shock waves were studied and used to measure dense plasma opacities and matter properties under extreme conditions. This data remains important for the development of theoretical models of matter. Powerful pulsed facilities (lasers, electric explosion installations, and charged particle accelerators) were constructed to extend opportunities for the HEDP research. One of their main goals is to study inertial confinement fusion. HEDP technologies and results are very useful in space and astrophysical research, and on the contrary, astrophysical studies enrich HEDP with new models, problems and solutions.

  4. High Current Energy Recovery Linac at BNL

    SciTech Connect

    Vladimir N. Litvinenko; Donald Barton; D. Beavis; Ilan Ben-Zvi; Michael Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X. Chang; Roger Connolly; D. Gassner; H. Hahn; A. Hershcovitch; H.C. Hseuh; P. Johnson; D. Kayran; J. Kewisch; R. Lambiase; G. McIntyre; W. Meng; T. C. Nehring; A. Nicoletti; D. Pate; J. Rank; T. Roser; T. Russo; J. Scaduto; K. Smith; T. Srinivasan-Rao; N. Williams; K.-C. Wu; Vitaly Yakimenko; K. Yip; A. Zaltsman; Y. Zhao; H. Bluem; A. Burger; Mike Cole; A. Favale; D. Holmes; John Rathke; Tom Schultheiss; A. Todd; J. Delayen; W. Funk; L. Phillips; Joe Preble

    2004-08-01

    We present the design, the parameters of a small test Energy Recovery Linac (ERL) facility, which is under construction at Collider-Accelerator Department, BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. A possibility for future up-grade to a two-pass ERL is considered. The heart of the facility is a 5-cell 700 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. ERL is also perfectly suited for a far-IR FEL. We present the status and our plans for construction and commissioning of this facility.

  5. HIGH CURRENT ENERGY RECOVERY LINAC AT BNL.

    SciTech Connect

    LITVINENKO,V.N.; BEN-ZVI,I.; BARTON,D.S.; ET AL.

    2005-05-16

    We present the design and parameters of an energy recovery linac (ERL) facility, which is under construction in the Collider-Accelerator Department at BNL. This R&D facility has the goal of demonstrating CW operation of an ERL with an average beam current in the range of 0.1-1 ampere and with very high efficiency of energy recovery. The possibility of a future upgrade to a two-pass ERL is also being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with strong Higher Order Mode (HOM) damping. The flexible lattice of the ERL provides a test-bed for exploring issues of transverse and longitudinal instabilities and diagnostics of intense CW electron beams. This ERL is also perfectly suited for a far-IR FEL. We present the status and plans for construction and commissioning of this facility.

  6. Impact of urban WWTP and CSO fluxes on river peak flow extremes under current and future climate conditions.

    PubMed

    Keupers, Ingrid; Willems, Patrick

    2013-01-01

    The impact of urban water fluxes on the river system outflow of the Grote Nete catchment (Belgium) was studied. First the impact of the Waste Water Treatment Plant (WWTP) and the Combined Sewer Overflow (CSO) outflows on the river system for the current climatic conditions was determined by simulating the urban fluxes as point sources in a detailed, hydrodynamic river model. Comparison was made of the simulation results on peak flow extremes with and without the urban point sources. In a second step, the impact of climate change scenarios on the urban fluxes and the consequent impacts on the river flow extremes were studied. It is shown that the change in the 10-year return period hourly peak flow discharge due to climate change (-14% to +45%) was in the same order of magnitude as the change due to the urban fluxes (+5%) in current climate conditions. Different climate change scenarios do not change the impact of the urban fluxes much except for the climate scenario that involves a strong increase in rainfall extremes in summer. This scenario leads to a strong increase of the impact of the urban fluxes on the river system. PMID:23787302

  7. The 1859 Solar-Terrestrial Disturbance And the Current Limits of Extreme Space Weather Activity

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Svalgaard, L.

    2004-10-01

    It is generally appreciated that the September 1859 solar-terrestrial disturbance, the first recognized space weather event, was exceptionally large. How large and how exceptional? To answer these questions, we compiled rank order lists of the various measures of solar-induced disturbance for events from 1859 to the present. The parameters considered included: magnetic crochet amplitude, solar energetic proton fluence (McCracken et al., 2001a), Sun-Earth disturbance transit time, geomagnetic storm intensity, and low-latitude auroral extent. While the 1859 event has close rivals or superiors in each of the above categories of space weather activity, it is the only documented event of the last ˜150 years that appears at or near the top of all of the lists. Taken together, the top-ranking events in each of the disturbance categories comprise a set of benchmarks for extreme space weather activity.

  8. The high current experiment: First results

    SciTech Connect

    Seidl, Peter A.; Baca, D.; Bieniosek, F.M.; Faltens, A.; Lund, S.M.; Molvik, A.W.; Prost, L.R.; Waldron, W.L.

    2002-05-26

    The High Current Experiment (HCX) is being assembled at Lawrence Berkeley National Laboratory as part of the US program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge dominated heavy-ion beams at high spacecharge intensity (line-charge density {approx} 0.2 {micro}C/m) over long pulse durations (>4 {micro}s). This machine will test transport issues at a driver-relevant scale resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, lost-particle induced electron effects, and longitudinal bunch control. We present the first experimental results carried out with the coasting K{sup +} ion beam transported through the first 10 electrostatic transport quadrupoles and associated diagnostics. Later phases of the experiment will include more electrostatic lattice periods to allow more sensitive tests of emittance growth, and also magnetic quadrupoles to explore similar issues in magnetic channels with a full driver scale beam.

  9. The high current experiment: First results

    NASA Astrophysics Data System (ADS)

    Seidl, P. A.; Baca, D.; Bieniosek, F. M.; Faltens, A.; Lund, S. M.; Molvik, A. W.; Prost, L. R.; Waldron, W. L.

    2002-07-01

    The High Current Experiment (HCX) is being assembled at Lawrence Berkeley National Laboratory as part of the U.S. program to explore heavy ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge dominated heavy ion beams at high space-charge intensity (line-charge density [similar] 0.2 [mu]C/m) over long pulse durations (>4 [mu]s). This machine will test transport issues at a driver-relevant scale resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, lost-particle induced electron effects, and longitudinal bunch control. We present the first experimental results carried out with the coasting K+ ion beam transported through the first 10 electrostatic transport quadrupoles and associated diagnostics. Later phases of the experiment will include more electrostatic lattice periods to allow more sensitive tests of emittance growth, and also magnetic quadrupoles to explore similar issues in magnetic channels with a full driver scale beam.

  10. Metronidazole as a protector of cells from electromagnetic radiation of extremely high frequencies

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Pavel E.; Malinina, Ulia A.; Popyhova, Era B.; Rogacheva, Svetlana M.; Somov, Alexander U.

    2006-08-01

    It is well known that weak electromagnetic fields of extremely high frequencies cause significant modification of the functional status of biological objects of different levels of organization. The aim of the work was to study the combinatory effect of metronidazole - the drug form of 1-(2'hydroxiethil)-2-methil-5-nitroimidazole - and electromagnetic radiation of extremely high frequencies (52...75 GHz) on the hemolytic stability of erythrocytes and hemotaxis activity of Infusoria Paramecium caudatum.

  11. High voltage compliance constant current ballast

    NASA Technical Reports Server (NTRS)

    Rosenthal, L. A.

    1976-01-01

    A ballast circuit employing a constant current diode and a vacuum tube that can provide a constant current over a voltage range of 1000 volts. The simple circuit can prove useful in studying voltage breakdown characteristics.

  12. Equiatomic CoPt thin films with extremely high coercivity

    SciTech Connect

    Varghese, Binni; Piramanayagam, S. N. Yang, Yi; Kai Wong, Seng; Khume Tan, Hang; Kiat Lee, Wee; Okamoto, Iwao

    2014-05-07

    In this paper, magnetic and structural properties of near-equiatomic CoPt thin films, which exhibited a high coercivity in the film-normal direction—suitable for perpendicular magnetic recording media applications—are reported. The films exhibited a larger coercivity of about 6.5 kOe at 8 nm. The coercivity showed a monotonous decrease as the film thickness was increased. The transmission electron microscopy images indicated that the as fabricated CoPt film generally consists of a stack of magnetically hard hexagonal-close-packed phase, followed by stacking faults and face-centred-cubic phase. The thickness dependent magnetic properties are explained on the basis of exchange-coupled composite media. Epitaxial growth on Ru layers is a possible factor leading to the unusual observation of magnetically hard hcp-phase at high concentrations of Pt.

  13. Extremely high negative electron affinity of diamond via magnesium adsorption

    NASA Astrophysics Data System (ADS)

    O'Donnell, K. M.; Edmonds, M. T.; Tadich, A.; Thomsen, L.; Stacey, A.; Schenk, A.; Pakes, C. I.; Ley, L.

    2015-07-01

    We report large negative electron affinity (NEA) on diamond (100) using magnesium adsorption on a previously oxygen-terminated surface. The measured NEA is up to (-2.01 ±0.05 ) eV, the largest reported negative electron affinity to date. Despite the expected close relationship between the surface chemistry of Mg and Li species on oxygen-terminated diamond, we observe differences in the adsorption properties between the two. Most importantly, a high-temperature annealing step is not required to activate the Mg-adsorbed surface to a state of negative electron affinity. Diamond surfaces prepared by this procedure continue to possess negative electron affinity after exposure to high temperatures, air, and even immersion in water.

  14. Effect of High Temperature on Extreme Substrate Acidification by Geranium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cause of sudden substrate pH decline by geranium is unknown and it may be due to high temperature and/or low P. ‘Designer Dark Red’ Geraniums were grown in two experiments and the first tested the effect of four temperatures (57/50, 64/57, 72/64 and 79/72º F day/night) on substrate acidificatio...

  15. Adaptation potential of naturally ventilated barns to high temperature extremes: The OptiBarn project

    NASA Astrophysics Data System (ADS)

    Menz, Christoph

    2016-04-01

    Climate change interferes with various aspects of the socio-economic system. One important aspect is its influence on animal husbandry, especially dairy faming. Dairy cows are usually kept in naturally ventilated barns (NVBs) which are particular vulnerable to extreme events due to their low adaptation capabilities. An effective adaptation to high outdoor temperatures for example, is only possible under certain wind and humidity conditions. High temperature extremes are expected to increase in number and strength under climate change. To assess the impact of this change on NVBs and dairy cows also the changes in wind and humidity needs to be considered. Hence we need to consider the multivariate structure of future temperature extremes. The OptiBarn project aims to develop sustainable adaptation strategies for dairy housings under climate change for Europe, by considering the multivariate structure of high temperature extremes. In a first step we identify various multivariate high temperature extremes for three core regions in Europe. With respect to dairy cows in NVBs we will focus on the wind and humidity field during high temperature events. In a second step we will use the CORDEX-EUR-11 ensemble to evaluate the capability of the RCMs to model such events and assess their future change potential. By transferring the outdoor conditions to indoor climate and animal wellbeing the results of this assessment can be used to develop technical, architectural and animal specific adaptation strategies for high temperature extremes.

  16. Field aligned current study during the solar declining- extreme minimum of 23 solar cycle

    NASA Astrophysics Data System (ADS)

    Nepolian, Jeni Victor; Kumar, Anil; C, Panneerselvam

    Field Aligned Current (FAC) density study has been carried out during the solar declining phase from 2004 to 2006 of the 23rd solar cycle and the ambient terrestrial magnetic field of the extended minimum period of 2008 and 2009. We mainly depended on CHAMP satellite data (http://isdc.gfz-potsdam.de/) for computing the FAC density with backup of IGRF-10 model. The study indicates that, the FAC is controlled by quasi-viscous processes occurring at the flank of the earth’s magnetosphere. The dawn-dusk conventional pattern enhanced during disturbed days. The intensity of R1 current system is higher than the R2 current system. Detailed results will be discussed in the conference.

  17. Extremely high electron mobility in a phonon-glass semimetal.

    PubMed

    Ishiwata, S; Shiomi, Y; Lee, J S; Bahramy, M S; Suzuki, T; Uchida, M; Arita, R; Taguchi, Y; Tokura, Y

    2013-06-01

    The electron mobility is one of the key parameters that characterize the charge-carrier transport properties of materials, as exemplified by the quantum Hall effect as well as high-efficiency thermoelectric and solar energy conversions. For thermoelectric applications, introduction of chemical disorder is an important strategy for reducing the phonon-mediated thermal conduction, but is usually accompanied by mobility degradation. Here, we show a multilayered semimetal β-CuAgSe overcoming such a trade-off between disorder and mobility. The polycrystalline ingot shows a giant positive magnetoresistance and Shubnikov de Haas oscillations, indicative of a high-mobility small electron pocket derived from the Ag s-electron band. Ni doping, which introduces chemical and lattice disorder, further enhances the electron mobility up to 90,000 cm(2) V(-1) s(-1) at 10 K, leading not only to a larger magnetoresistance but also a better thermoelectric figure of merit. This Ag-based layered semimetal with a glassy lattice is a new type of promising thermoelectric material suitable for chemical engineering. PMID:23603851

  18. In-vehicle extremity injuries from improvised explosive devices: current and future foci

    PubMed Central

    Ramasamy, Arul; Masouros, Spyros D.; Newell, Nicolas; Hill, Adam M.; Proud, William G.; Brown, Katherine A.; Bull, Anthony M. J.; Clasper, Jon C.

    2011-01-01

    The conflicts in Iraq and Afghanistan have been epitomized by the insurgents' use of the improvised explosive device against vehicle-borne security forces. These weapons, capable of causing multiple severely injured casualties in a single incident, pose the most prevalent single threat to Coalition troops operating in the region. Improvements in personal protection and medical care have resulted in increasing numbers of casualties surviving with complex lower limb injuries, often leading to long-term disability. Thus, there exists an urgent requirement to investigate and mitigate against the mechanism of extremity injury caused by these devices. This will necessitate an ontological approach, linking molecular, cellular and tissue interaction to physiological dysfunction. This can only be achieved via a collaborative approach between clinicians, natural scientists and engineers, combining physical and numerical modelling tools with clinical data from the battlefield. In this article, we compile existing knowledge on the effects of explosions on skeletal injury, review and critique relevant experimental and computational research related to lower limb injury and damage and propose research foci required to drive the development of future mitigation technologies. PMID:21149353

  19. In-vehicle extremity injuries from improvised explosive devices: current and future foci.

    PubMed

    Ramasamy, Arul; Masouros, Spyros D; Newell, Nicolas; Hill, Adam M; Proud, William G; Brown, Katherine A; Bull, Anthony M J; Clasper, Jon C

    2011-01-27

    The conflicts in Iraq and Afghanistan have been epitomized by the insurgents' use of the improvised explosive device against vehicle-borne security forces. These weapons, capable of causing multiple severely injured casualties in a single incident, pose the most prevalent single threat to Coalition troops operating in the region. Improvements in personal protection and medical care have resulted in increasing numbers of casualties surviving with complex lower limb injuries, often leading to long-term disability. Thus, there exists an urgent requirement to investigate and mitigate against the mechanism of extremity injury caused by these devices. This will necessitate an ontological approach, linking molecular, cellular and tissue interaction to physiological dysfunction. This can only be achieved via a collaborative approach between clinicians, natural scientists and engineers, combining physical and numerical modelling tools with clinical data from the battlefield. In this article, we compile existing knowledge on the effects of explosions on skeletal injury, review and critique relevant experimental and computational research related to lower limb injury and damage and propose research foci required to drive the development of future mitigation technologies. PMID:21149353

  20. High Performance Multivariate Visual Data Exploration for Extremely Large Data

    SciTech Connect

    Rubel, Oliver; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Ahern, Sean; Weber, Gunther H.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes; Prabhat,

    2008-08-22

    One of the central challenges in modern science is the need to quickly derive knowledge and understanding from large, complex collections of data. We present a new approach that deals with this challenge by combining and extending techniques from high performance visual data analysis and scientific data management. This approach is demonstrated within the context of gaining insight from complex, time-varying datasets produced by a laser wakefield accelerator simulation. Our approach leverages histogram-based parallel coordinates for both visual information display as well as a vehicle for guiding a data mining operation. Data extraction and subsetting are implemented with state-of-the-art index/query technology. This approach, while applied here to accelerator science, is generally applicable to a broad set of science applications, and is implemented in a production-quality visual data analysis infrastructure. We conduct a detailed performance analysis and demonstrate good scalability on a distributed memory Cray XT4 system.

  1. MACHINE PROTECTION FOR HIGH AVERAGE CURRENT LINACS

    SciTech Connect

    Jordan, Kevin; Allison, Trent; Evans, Richard; Coleman, James; Grippo, Albert

    2003-05-01

    A fully integrated Machine Protection System (MPS) is critical to efficient commissioning and safe operation of all high current accelerators. The Jefferson Lab FEL [1,2] has multiple electron beam paths and many different types of diagnostic insertion devices. The MPS [3] needs to monitor both the status of these devices and the magnet settings which define the beam path. The matrix of these devices and beam paths are programmed into gate arrays, the output of the matrix is an allowable maximum average power limit. This power limit is enforced by the drive laser for the photocathode gun. The Beam Loss Monitors (BLMs), RF status, and laser safety system status are also inputs to the control matrix. There are 8 Machine Modes (electron path) and 8 Beam Modes (average power limits) that define the safe operating limits for the FEL. Combinations outside of this matrix are unsafe and the beam is inhibited. The power limits range from no beam to 2 megawatts of electron beam power.

  2. High Current Hollow Cathode Plasma Plume Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Kamhawi, Hani; Williams, George J., Jr.

    2014-01-01

    Plasma plume measurements are reported for a hollow cathode assembly (HCA) operated at discharge currents of 50, 70, and 100 A at xenon flow rates between 19 - 46 standard cubic centimeter per minute. The HCA was centrally mounted in the NASA-300MS Hall Thruster and was operated in the "spot" and "plume" modes with additional data taken with an applied magnetic field. Langmuir probes, retarding potential analyzers, and optical emission spectroscopy were employed to measure plasma properties near the orifice of the HCA and to assess the charge state of the near-field plasma. Electron temperatures (2-6 electron volt) and plasma potentials are consistent with probe-measured values in previous investigations. Operation with an applied-field yields higher discharge voltages, increased Xe III production, and increased signals from the 833.5 nm C I line. While operating in plume mode and with an applied field, ion energy distribution measurements yield ions with energies significantly exceeding the applied discharge voltage. These findings are correlated with high-frequency oscillations associated with each mode.

  3. High Current Hollow Cathode Plasma Plume Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Kamhawi, Hani; Williams, George J., Jr.

    2013-01-01

    Plasma plume measurements are reported for a hollow cathode assembly (HCA) oper-ated at discharge currents of 50, 70, and 100 A at xenon ow rates between 19 - 46 sccm.The HCA was centrally mounted in the annulus of the NASA-300MS Hall Thruster andwas operated in the spot and plume modes with additional data taken with an appliedmagnetic eld. Langmuir probes, retarding potential analyzers, and optical emission spec-troscopy were employed to measure plasma properties near the orice of the HCA and toassess the charge state of the near-eld plasma. Electron temperatures (2-6 eV) and plasmapotentials are consistent with probe-measured values in previous investigations. Operationwith an applied-eld yields higher discharge voltages, increased Xe III production, andincreased signals from the 833.5 nm C I line. While operating in plume mode and with anapplied eld, ion energy distribution measurements yield ions with energies signicantlyexceeding the applied discharge voltage. These ndings are correlated with high-frequencyoscillations associated with each mode.

  4. Interannual to millennial variability of climate extreme indices over Europe: evidence from high resolution proxy data

    NASA Astrophysics Data System (ADS)

    Rimbu, Norel; Ionita, Monica; Lohmann, Gerrit

    2016-04-01

    Interannual to millennial time scale variability of precipitation (R20mm, Rx5day, R95pTOT), cold (TN10p, CSDI and CFD), heat (TX90p and WSDI) and drought (CDD) extreme climate indices is investigated using long-term observational and proxy records. We detect significant correlations between these indices and various high resolution proxy records like lake sediments from southern Germany, stable oxygen isotopes from Greenland ice cores and stable oxygen isotopes from Red Sea corals during observational period. The analysis of long-term reanalysis data in combination with extreme climate indices and proxy data reveals that distinct atmospheric circulation patterns explain most of the identified relationships. In particular, we show that a sediment record from southern Germany (lake Ammersee), which records flood frequency of River Ammer during the last 5500 years, is related to a wave-train atmospheric circulation pattern with a pronounced negative center over western Europe. We show that high frequency of River Ammer floods is related not only to high frequency of extreme precipitation events (R95p) in the Ammer region but also with significant positive anomalies of various extreme temperature indices (TX90p and TXx) over northeastern Europe. Such extreme temperatures are forced by cloudiness anomaly pattern associated with flood related atmospheric circulation pattern. Based on this record we discuss possible interannual to millennial scale variations of extreme precipitation and temperature indices over Europe during the last 5500 years. Coherent variations of extreme precipitation and temperature indices over Europe and stable oxygen isotopes from Greenland ice cores and northern Red Sea corals during observational period are related to atmospheric blocking variability in the North Atlantic region. Possible variations of climate extreme indices during different time slices of the Holocene period and their implications for future extreme climate variability are

  5. A high-energy, high-current ion implantation system

    NASA Astrophysics Data System (ADS)

    Rose, Peter H.; Faretra, Ronald; Ryding, Geoffery

    1985-01-01

    High current (Pre-DepTM) ion implanters, operating at 80 keV, have met a need in the semiconductor industry. For certain processes, higher energies are required, either to penetrate a surface layer or to place the dopant ion at a greater depth. The Eaton/Nova Model NV10-160 Pre-DepTM Ion Implanter has been developed to meet those special needs. Beam currents as high as 10.0 mA are available at energies up to 160 keV for routine production applications. The system has also been qualified for low current, low dose operation (1011 ions cm-2) and this unique versatility provides the Process and Equipment Engineers with a powerful new tool. The Model NV10-160 also utilizes the Nova-designed, double disk interchange processing system to minimize inactive beam time so that wafer throughputs, up to 300 wafers/h, are achievable on a routine basis. DatalockTM, a computer driven implant monitoring system and AT-4, the Nova cassette-to-cassette wafer loader, are available as standard options. As a production machine, the Model NV10-160 with its high throughput capability, will reduce the implant cost per wafer significantly for doses above 10 × 1015 ions/cm2. Performance patterns are now emerging as some twenty-five systems have now been shipped. This paper summarizes the more important characteristics and reviews the major design features of the NV10-160.

  6. Weak Line Quasars at High Redshift: Extremely High Accretion Rate Sources?

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad

    2011-10-01

    The Sloan Digital Sky Survey has recently discovered a remarkable group of ~80 quasars at z=2.2-5.9 with extremely weak emission lines in their rest-frame UV spectra. We propose to extend our XMM-Newton observations of such sources and obtain imaging spectroscopy of four quasars of this class with a total exposure time of 165 ks, providing ~1000 photons per source. This will enable an accurate measurement of the hard-X-ray photon index required for a robust determination of the accretion rate in each source. Steep spectral slopes will indicate that high accretion rates may be responsible for the intrinsic weakness of the UV emission lines. The proposed observations will lead to new insights about the accretion process and broad emission line formation in all active galactic nuclei.

  7. Weak Line Quasars at High Redshift: Extremely High Accretion Rate Sources?

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad

    2010-10-01

    The Sloan Digital Sky Survey has recently discovered a remarkable group of ~80 quasars at z=2.2-5.9 with extremely weak emission lines in their rest-frame UV spectra. We propose to extend our XMM-Newton observations of such sources and obtain imaging spectroscopy of four quasars of this class with a total exposure time of 165 ks, providing ~1000 photons per source. This will enable an accurate measurement of the hard-X-ray photon index required for a robust determination of the accretion rate in each source. Steep spectral slopes will indicate that high accretion rates may be responsible for the intrinsic weakness of the UV emission lines. The proposed observations will lead to new insights about the accretion process and broad emission line formation in all active galactic nuclei.

  8. Weak Line Quasars at High Redshift: Extremely High Accretion Rate Sources?

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad

    2013-10-01

    The Sloan Digital Sky Survey has discovered a remarkable group of ~100 quasars with extremely weak emission lines in their rest-frame optical-UV spectra. We propose to extend our XMM-Newton observations of such sources and obtain imaging spectroscopy of six quasars of this class with a total exposure time of 128 ks, providing ~1000 photons per source. This will enable an accurate measurement of the hard-X-ray photon index required for a robust determination of the accretion rate in each source. Steep spectral slopes will indicate that high accretion rates may be responsible for the intrinsic weakness of the optical-UV emission lines. The proposed observations will lead to new insights about the accretion process and broad emission line formation in all active galactic nuclei.

  9. Combining hydraulic and granular flow extremes for density currents by depth averaging two phase flow equations.

    NASA Astrophysics Data System (ADS)

    Cordoba, G. A.; Sheridan, M.; Pitman, B.

    2009-05-01

    Ground-hugging particle-laden flows constitute some of the most dangerous natural phenomena on Earth. Such currents, in the form of snow avalanches, pyroclastic flows, debris flows, lahars, and landslides, are among the most destructive processes in nature. Humans tend to settle in areas near rich soils, volcanoes, or watercourses, all of which could be strongly affected by these dangerous flows. In order to improve risk preparedness and site management in the affected zones, an appropriate knowledge of these natural hazardous phenomena is required. Their evolution in time, flow dynamics and run out distance are key aspects that help in the planning for hazardous events, development of hazardous regions and design of management policy to prepare in advance of potential natural disasters. This paper describes a depth-averaged model for two phase flows that is currently in develop at the University at Buffalo. It is presently implemented within the TITAN2D framework to improve the version that currently simulates dry geophysical mass flows over natural-scale terrains. The initial TITAN2D code was developed to simulate granular flow. But because the introduction of an interstitial fluid strongly modifies the dynamics of the flow, a new, more general, two-phase model was developed to account for a broad range in volume fraction of solids. The proposed mathematical model depth-integrates the Navier-Stokes equations for each phase, solid and fluid. The solid phase is modeled assuming a Coulomb constitutive behavior (at the theoretical limit of pure solids), whereas the fluid phase conforms to a typical hydraulic approach (at the limit of pure fluid). The linkage for compositions between the pure end-member phases is accommodated by the inclusion of a phenomenological-based drag coefficient. The model is capable of simulating particle volumetric fractions as dilute as 0.001 and as concentrated as 0.55.

  10. Extreme gamma-ray outburst during the current Crab Nebula flare

    NASA Astrophysics Data System (ADS)

    Hays, E.; Buehler, R.; D'Ammand, F.

    2011-04-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, previously reported a new gamma-ray flare from the direction of the Crab Nebula beginning on the 9th of April (ATel #3276). The increased emission was afterwards confirmed by the AGILE satellite (ATel #3282).The Crab Nebula is currently also being monitored by Chandra, which observed a bright knot east of the pulsar (ATel #3283), similar to previous observations in the September 2010 flare.

  11. Single-growth embedded epitaxy AlGaAs injection lasers with extremely low threshold currents

    SciTech Connect

    Katz, J.; Margalit, S.; Wilt, D.; Chen, P.C.; Yariv, A.

    1980-12-01

    A new type of strip-geometry AlGaAs double-heterostructure laser with an embedded optical waveguide has been developed. The new structure is fabricated using a single step of epitaxial growth. Lasers with threshold currents as low as 9.5 mA (150 ..mu..m long) were obtained. These lasers exhibit operation in a single spatial and longitudinal mode, have differential quantum efficiencies exceeding 45%, and a characteristic temperature of 175/sup 0/ C. They emit more than 12 mW/facet of optical power without any kinks.

  12. Assessing the variability in extreme high water levels and the implications for coastal flood risk

    NASA Astrophysics Data System (ADS)

    Quinn, Niall; Lewis, Matthew; Wadey, Matthew; Haigh, Ivan

    2014-05-01

    Assessing the variability in extreme high water levels and the implications for coastal flood risk In this research we assess the temporal variability in the time-series of extreme water levels at 44 A- Class tide gauges around the UK. Extreme (> 99th percentile) storm tide events, sampled from water level measurements taken every 15 minutes between 1993 and 2012, were analysed at each site, and the variability in elevation relative to a given event storm tide peak was quantified. The magnitude of the variability in the time-series was found to be both spatially variable across the UK, and temporally variable relative to the time of the high water. Boundary water levels associated with a range of event magnitudes at case study locations around the UK were used to force two-dimensional hydrodynamic models to examine the importance of storm tide time-series uncertainty to flood risk predictions. The comparison of inundation extent, depth, and number of buildings affected demonstrated the importance of accurately defining the duration and magnitude of defence exceedance. For example, given a current 1 in 200 year event magnitude at Portsmouth (UK), the predicted number of buildings inundated differed by more than 30% when contrasting simulations forced with the 5th percentile time-series relative to those forced with the 95th percentile time-series. The results clearly indicate that variability in the time-series of the storm tide can have considerable influence upon the duration and magnitude by which defences are exceeded, hence with implications for coastal flood risk assessments. Therefore, further evaluating and representing this uncertainty in future flood risk assessments is vital, while the 5th and 95th percentile time-series defined in this research provide a tool for coastal flood modellers. Only defence overflow-induced inundation was examined in this research. However, it is expected that variability in storm tide time-series will also have important

  13. Extremely Large Diamagnetic Cavities Observed In The Dayside High-altitute Cusps

    NASA Astrophysics Data System (ADS)

    Chen, Jiasheng; Fritz, Theodore A.

    Some extremely large diamagnetic cavities have been observed in April, 1999 when the POLAR spacecraft was crossing through the dayside high-altitude cusp regions. These diamagnetic cavities were associated with strong magnetic field turbulence. Some of the diamagnetic cavities were independent of the IMF directions, which is unexpected by the current MHD models, suggesting that the diamagnetic cavities are different from the magnetospheric sash. The size of the cavities were found to be as large as 6 Re. Associated with these cavities are ions with energies from 40 keV up to 8 MeV that are more typical of the trapped ring current and radiation belt populations than the solar wind. The intensities of the energetic ions were observed to increase by as large as four orders of the magnitudes during the cavity crossings, indicating the dayside high-altitude cusp diamagnetic cavity is a key region for transferring the solar wind energy, mass, and momentum into the Earth's magnetosphere. The charge state distribution of these cusp cavity ions was indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. By their geometry cusp mag- netic field lines are connected to all of the magnetopause boundary layers and these cavity charged particles will form an energetic particle layer on the magnetopause. These energetic particles in the cusp diamagnetic cavity together with the cusp's con- nectivity have significant global impacts on the geospace environment research and will be shedding light on the long-standing unsolved fundamental issue about the ori- gins of the energetic particles in the ring current and in upstream ion events.

  14. Characterization of high-current, high-temperature superconductor current lead elements

    SciTech Connect

    Niemann, R.C.; Evans, D.J.; Fisher, B.L.; Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J.

    1996-08-01

    The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures.

  15. Lightweight, High-Current Welding Gun

    NASA Technical Reports Server (NTRS)

    Starck, Thomas F.; Brennan, Andrew D.

    1989-01-01

    Lighweight resistance-welding, hand-held gun supplies alternating or direct current over range of 600 to 4,000 A and applies forces from 40 to 60 lb during welding. Used to weld metal sheets in multilayered stacks.

  16. Statistical coupling between solar wind conditions and extreme geomagnetically induced current events

    NASA Astrophysics Data System (ADS)

    Pulkkinen, A. A.; Pirjola, R.; Viljanen, A.

    2007-12-01

    Recent advances in global MHD-based modeling of geomagnetically induced currents (GIC) from upstream solar wind (L1 observations) to the ground have opened new avenues for physics-based space weather forecasting. More specifically, Pulkkinen et al . (2007, Annales Geophysicae) showed that global MHD was able to generate realistic, in terms of spatiotemporal structure, GIC fluctuations having amplitudes comparable to the observed values. However, the situation is significantly more demanding if heliospheric models instead of L1 observations are used to generate the magnetospheric/GIC activity. Although current MHD-based solar wind models are capable of producing realistic large-scale behavior of the solar wind, for example, the turbulent interplanetary magnetic field (IMF) fluctuations are missing to a large degree. This obviously poses a problem for GIC modeling as the turbulent nature of IMF is possibly one of the main sources for large GIC. In this work a model for statistical coupling between hourly solar wind parameters and maximum GIC values observed on the ground is constructed. OMNI and IMAGE magnetometer array data from 1995-2006 are facilitated in the construction of the model. It is shown that there is a clear statistical coupling between the solar wind parameters, most importantly solar wind convective electric field and maximum GIC. The established connection between GIC and large-scale solar wind features enables new strategies for GIC forecasting even in the (partial) absence of information about turbulent IMF. In one possible strategy one would use heliospheric MHD models to generate large-scale solar wind features at L1, which would then be used to generate statistical estimate for GIC. In this paper the generation and the usage of the statistics in space weather forecasting and in other contexts is discussed.

  17. Developing high brightness and high current beams for HIF injectors

    SciTech Connect

    Ahle, Larry; Grote, Dave; Kwan, Joe

    2002-05-24

    The US Heavy Ion Fusion Virtual National Laboratory is continuing research into ion sources and injectors that simultaneously provide high current (0.5-1.0 Amps) and high brightness (normalized emittance better than 1.0 {pi}-mm-mr). The central issue of focus is whether to continue pursuing the traditional approach of large surface ionization sources or to adopt a multiaperture approach that transports many smaller ''beamlets'' separately at low energies before allowing them to merge. For the large surface source concept, the recent commissioning of the 2-MeV injector for the High Current eXperiment has increased our understanding of the beam quality limitations for these sources. We have also improved our techniques for fabricating large diameter aluminosilicate sources to improve lifetime and emission uniformity. For the multiaperture approach, we are continuing to study the feasibility of small surface sources and a RF induced plasma source in preparation for beamlet merging experiments, while continuing to run computer simulations for better understanding of this alternate concept. Experiments into both architectures will be performed on a newly commissioned ion source test stand at LLNL called STS-500. This stand test provides a platform for testing a variety of ion sources and accelerating structures with 500 kV, 17-microsecond pulses. Recent progress in these areas will be discussed as well as plans for future experiments.

  18. High pressure research at the Partnership for eXtreme Xtallography (PX^2) Project

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Dera, P.; Zhang, J.; Eng, P. J.; Stubbs, J.; Prakapenka, V.; Rivers, M. L.

    2015-12-01

    The Partnership for eXtreme Xtallography (PX^2) project is a collaboration between the University of Hawaii and GeoSoilEnviroCARS (GSECARS), located at the Advanced Photon Source (APS) experimental station 13-BM-C. PX^2 is providing new capabilities for high-pressure diamond anvil cell research at the GSECARS APS beamline. This beamline provides focused x-rays at two fixed energies: 15 and 29 keV, and a unique 6-circle heavy duty diffractometer, optimized for a variety of advanced crystallography experiments including interface studies, powder and single crystal structure determination, equation of state studies and thermal diffuse scattering. Currently we support high pressure and temperature experiments using resistively heated diamond anvil cells, and have achieved P-T conditions of 100 GPa and 1000 K. Results of multiple recent experiments, including powder and single crystal diffraction over a range of P-T conditions, equations of state and thermal diffuse scattering will be presented to demonstrate the experimental capabilities. These new capabilities are available to all researchers interested in studying deep earth materials through the APS General User Proposal system.

  19. Modular High Current Test Facility at LLNL

    SciTech Connect

    Tully, L K; Goerz, D A; Speer, R D; Ferriera, T J

    2008-05-20

    This paper describes the 1 MA, 225 kJ test facility in operation at Lawrence Livermore National Laboratory (LLNL). The capacitor bank is constructed from three parallel 1.5 mF modules. The modules are capable of switching simultaneously or sequentially via solid dielectric puncture switches. The bank nominally operates up to 10 kV and reaches peak current with all three cabled modules in approximately 30 {micro}s. Parallel output plates from the bank allow for cable or busbar interfacing to the load. This versatile bank is currently in use for code validation experiments, railgun related activities, switch testing, and diagnostic development.

  20. How extreme are extremes?

    NASA Astrophysics Data System (ADS)

    Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

    2016-04-01

    High temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. Heat-wave indicators have been mainly developed with the aim of capturing the potential impacts on specific sectors (agriculture, health, wildfires, transport, power generation and distribution). However, the ability to capture the occurrence of extreme temperature events is an essential property of a multi-hazard extreme climate indicator. Aim of this study is to develop a standardized heat-wave indicator, that can be combined with other indices in order to describe multiple hazards in a single indicator. The proposed approach can be used in order to have a quantified indicator of the strenght of a certain extreme. As a matter of fact, extremes are usually distributed in exponential or exponential-exponential functions and it is difficult to quickly asses how strong was an extreme events considering only its magnitude. The proposed approach simplify the quantitative and qualitative communication of extreme magnitude

  1. High-current ion-ring accelerator

    SciTech Connect

    Sudan, R.N. )

    1993-03-15

    An accelerator concept is outlined which enables 10[sup 15] to 10[sup 18] ions in the form of a charge neutralized ion ring to be accelerated to GeV energies. A repetition rate of 10 Hz will deliver an average current in the range of 0.1 A.

  2. Weak Line Quasars at High Redshift: Extremely High Accretion Rates or Anemic Broad-line Regions?

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad; Trakhtenbrot, Benny; Anderson, Scott F.; Brandt, W. N.; Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Lira, Paulina; Netzer, Hagai; Plotkin, Richard M.; Richards, Gordon T.; Schneider, Donald P.; Strauss, Michael A.

    2010-10-01

    We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDSS J114153.34+021924.3 at z = 3.55 and SDSS J123743.08+630144.9 at z = 3.49. In both sources, we detect an unusually weak broad Hβ line and place tight upper limits on the strengths of their [O III] lines. Virial, Hβ-based black hole mass determinations indicate normalized accretion rates of L/L Edd=0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of Γ = 1.91+0.24 -0.22, which supports the virial L/L Edd determination in this source. Our results suggest that the weakness of the broad emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad emission line region properties.

  3. WEAK LINE QUASARS AT HIGH REDSHIFT: EXTREMELY HIGH ACCRETION RATES OR ANEMIC BROAD-LINE REGIONS?

    SciTech Connect

    Shemmer, Ohad; Trakhtenbrot, Benny; Netzer, Hagai; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Lira, Paulina; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

    2010-10-20

    We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDSS J114153.34+021924.3 at z = 3.55 and SDSS J123743.08+630144.9 at z = 3.49. In both sources, we detect an unusually weak broad H{beta} line and place tight upper limits on the strengths of their [O III] lines. Virial, H{beta}-based black hole mass determinations indicate normalized accretion rates of L/L {sub Edd}=0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of {Gamma} = 1.91{sup +0.24} {sub -0.22}, which supports the virial L/L {sub Edd} determination in this source. Our results suggest that the weakness of the broad emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad emission line region properties.

  4. Extreme High and Low Temperature Operation of the Silicon-On-Insulator Type CHT-OPA Operational Amplifier

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    A new operational amplifier chip based on silicon-on-insulator technology was evaluated for potential use in extreme temperature environments. The CHT-OPA device is a low power, precision operational amplifier with rail-to-rail output swing capability, and it is rated for operation between -55 C and +225 C. A unity gain inverting circuit was constructed utilizing the CHT-OPA chip and a few passive components. The circuit was evaluated in the temperature range from -190 C to +200 C in terms of signal gain and phase shift, and supply current. The investigations were carried out to determine suitability of this device for use in space exploration missions and aeronautic applications under wide temperature incursion. Re-restart capability at extreme temperatures, i.e. power switched on while the device was soaked at extreme temperatures, was also investigated. In addition, the effects of thermal cycling under a wide temperature range on the operation of this high performance amplifier were determined. The results from this work indicate that this silicon-on-insulator amplifier chip maintained very good operation between +200 C and -190 C. The limited thermal cycling had no effect on the performance of the amplifier, and it was able to re-start at both -190 C and +200 C. In addition, no physical degradation or packaging damage was introduced due to either extreme temperature exposure or thermal cycling. The good performance demonstrated by this silicon-on-insulator operational amplifier renders it a potential candidate for use in space exploration missions or other environments under extreme temperatures. Additional and more comprehensive characterization is, however, required to establish the reliability and suitability of such devices for long term use in extreme temperature applications.

  5. Insulator damage in high current discharges

    NASA Astrophysics Data System (ADS)

    Ranon, P. M.; Kristiansen, M.; Lehr, F. M.; Hatfield, L. L.

    1986-11-01

    The degradation of the hold-off voltage capability of several composite candidates for railgun insulators was studied experimentally. The materials examined were BN, alumina (Coor's ceramic), and two types of laminated fiberglass/epoxy (FGE I and FGE II). Sample 1 cm thick plates of the insulators were inserted into a surface discharge switch (SDS) with a gap of 1.6 in., i.e., an initial hold-off voltage of 40 kV. FGE I retained the hold-off voltage for more than 10,000 shots at a current of 1 kA maximum, but degraded significantly after 50 shots at currents over 200 kA. BN shattered when the repetition rate exceeded 1 pulse/sec.

  6. A high performance current source inverter

    SciTech Connect

    Joos, G.; Moschopoulos, G.; Ziogas, P.D.

    1993-10-01

    A recent innovation in current source inverter (CSI) drives has been the introduction of pulsewidth modulation (PWM) for the purpose of improving the quality of the load currents and voltages. However, the typical six switch CSI circuit is not compatible with all standard PWM techniques thus limiting the number of schemes that can be used. The modified CSI circuit discussed in this paper removes most of the restrictions at the ``cost`` of an extra switch. Additional advantages include faster response times through modulation index control and higher efficiency. This paper includes a detailed steady-state analysis and design procedure. The feasibility and performance of the modified CSI are verified by simulation and experimental implementation on a 5 kVA converter.

  7. Architecture for high critical current superconducting tapes

    DOEpatents

    Jia, Quanxi; Foltyn, Stephen R.

    2002-01-01

    Improvements in critical current capacity for superconducting film structures are disclosed and include the use of, e.g., multilayer YBCO structures where individual YBCO layers are separated by a layer of an insulating material such as CeO.sub.2 and the like, a layer of a conducting material such as strontium ruthenium oxide and the like or by a second superconducting material such as SmBCO and the like.

  8. Wave-mixing with high-order harmonics in extreme ultraviolet region

    SciTech Connect

    Dao, Lap Van; Dinh, Khuong Ba; Le, Hoang Vu; Gaffney, Naylyn; Hannaford, Peter

    2015-01-12

    We report studies of the wave-mixing process in the extreme ultraviolet region with two near-infrared driving and controlling pulses with incommensurate frequencies (at 1400 nm and 800 nm). A non-collinear scheme for the two beams is used in order to spatially separate and to characterise the properties of the high-order wave-mixing field. We show that the extreme ultraviolet frequency mixing can be treated by perturbative, very high-order nonlinear optics; the modification of the wave-packet of the free electron needs to be considered in this process.

  9. Continuous and discrete extreme climatic events affecting the dynamics of a high-arctic reindeer population.

    PubMed

    Chan, Kung-Sik; Mysterud, Atle; Øritsland, Nils Are; Severinsen, Torbjørn; Stenseth, Nils Chr

    2005-10-01

    Climate at northern latitudes are currently changing both with regard to the mean and the temporal variability at any given site, increasing the frequency of extreme events such as cold and warm spells. Here we use a conceptually new modelling approach with two different dynamic terms of the climatic effects on a Svalbard reindeer population (the Brøggerhalvøya population) which underwent an extreme icing event ("locked pastures") with 80% reduction in population size during one winter (1993/94). One term captures the continuous and linear effect depending upon the Arctic Oscillation and another the discrete (rare) "event" process. The introduction of an "event" parameter describing the discrete extreme winter resulted in a more parsimonious model. Such an approach may be useful in strongly age-structured ungulate populations, with young and very old individuals being particularly prone to mortality factors during adverse conditions (resulting in a population structure that differs before and after extreme climatic events). A simulation study demonstrates that our approach is able to properly detect the ecological effects of such extreme climate events. PMID:16010537

  10. Nitrogen-enriched carbon with extremely high mesoporosity and tunable mesopore size for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoqing; Li, Chengfei; Fu, Ruowen

    2016-07-01

    As one of the most potential electrode materials for supercapacitors, nitrogen-enriched nanocarbons are still facing challenge of constructing developed mesoporosity for rapid mass transportation and tailoring their pore size for performance optimization and expanding their application scopes. Herein we develop a series of nitrogen-enriched mesoporous carbon (NMC) with extremely high mesoporosity and tunable mesopore size by a two-step method using silica gel as template. In our approach, mesopore size can be easily tailored from 4.7 to 35 nm by increasing the HF/TEOS volume ratio from 1/100 to 1/4. The NMC with mesopores of 6.2 nm presents the largest mesopore volume, surface area and mesopore ratio of 2.56 cm3 g-1, 1003 m2 g-1 and 97.7%, respectively. As a result, the highest specific capacitance of 325 F g-1 can be obtained at the current density of 0.1 A g-1, which can stay over 88% (286 F g-1) as the current density increases by 100 times (10 A g-1). This approach may open the doors for preparation of nitrogen-enriched nanocarbons with desired nanostructure for numerous applications.

  11. W(310) cold-field emission characteristics reflecting the vacuum states of an extreme high vacuum electron gun

    SciTech Connect

    Cho, Boklae; Shigeru, Kokubo; Oshima, Chuhei

    2013-01-15

    An extremely high vacuum cold-field electron emission (CFE) gun operating at pressures ranging from {approx}10{sup -8} Pa to {approx}10{sup -10} Pa was constructed. Only the CFE current emitting from W(310) surfaces revealed the existence of a 'stable region' with high current angular density just after tip flash heating. In the 'stable region,' the CFE current was damped very slowly. The presence of non-hydrogen gas eliminated this region from the plot. Improvement of the vacuum prolonged the 90% damping time of the CFE current from {approx}10 min to 800 min. The current angular density I{sup Prime} of CFE current was 60 and 250 {mu}A/sr in the 'stable region' for total CFE currents of 10 and 50 {mu}A, respectively. These results were about three times larger than I{sup Prime} when measured after the complete damping of the CFE current. The CFE gun generated bright scanning transmission electron microscopy images of a carbon nanotube at 30 kV.

  12. High-current density coils for high-radiation environments

    SciTech Connect

    Harvey, A.

    1981-01-01

    This paper concentrates on the problems of providing normal (that is, nonsuperconducting) magnet coils for present and short-term-future requirements where significant radiation doses are involved. Projects such as 100-mA deuteron accelerators and bundle diverter coils for TOKAMAKS are typical of applications where conventional organic insulation limited to 10/sup 10/ rads makes epoxy-based systems unacceptable. Moreover, even in present-day accelerators, radiation levels can be high enough to give rise to problems with oxidation of copper conductors if water is used in direct contact with the copper. The radiolytic oxygen, being formed in situ, cannot be controlled by external deoxygenators. An acceptable insulation for such environments has been described previously, and is being employed where radiation is expected to be a problem. Being a compacted magnesium oxide powder, the insulation has advantages. Analysis of constraints on maximum current densities achievable in such a coil construction, using computer codes, leads to coil configurations that operate at higher current densities than are usually found in directly cooled coils. An example of the thermal analysis of one coil configuration is given. The problems are addressed here.

  13. High-current plasma contactor neutralizer system

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Williamson, W. S.; Matossian, J. N.; Vourgourakis, E. J.; Burch, J. L.

    1989-01-01

    A plasma-contactor neutralizer system is described, for the stabilizing the Orbiter's potential during flights of the Atmospheric Laboratory for Applications and Science missions. The plasma contactor neutralizer will include a Xe plasma source that can provide steady-state ion-emission currents of up to 1.5 A. The Orbiter's potential will be maintained near that of the surrounding space plasma during electron-beam accelerator firings through a combination of ion emission from the Xe plasma source and electron collection from the ambient space plasma. Configuration diagrams and block diagrams are presented along with the performance characteristics of the system.

  14. High aspect ratio tungsten grating on ultrathin Si membranes for extreme UV lithography.

    PubMed

    Peng, Xinsheng; Ying, Yulong

    2016-09-01

    Extreme ultraviolet lithography is one of the modern lithography tools for high-volume manufacturing with 22 nm resolution and beyond. But critical challenges exist to the design and fabrication of large-scale and highly efficient diffraction transmission gratings, significantly reducing the feature sizes down to 22 nm and beyond. To achieve such a grating, the surface flatness, the line edge roughness, the transmission efficiency and aspect ratio should be improved significantly. Delachat et al (2015 Nanotechnology 26 108262) develop a full process to fabricate a tungsten diffraction grating on an ultrathin silicon membrane with higher aspect ratio up to 8.75 that met all the aforementioned requirements for extreme ultraviolet lithography. This process is fully compatible with standard industrial extreme ultraviolet lithography. PMID:27458188

  15. High aspect ratio tungsten grating on ultrathin Si membranes for extreme UV lithography

    NASA Astrophysics Data System (ADS)

    Peng, Xinsheng; Ying, Yulong

    2016-09-01

    Extreme ultraviolet lithography is one of the modern lithography tools for high-volume manufacturing with 22 nm resolution and beyond. But critical challenges exist to the design and fabrication of large-scale and highly efficient diffraction transmission gratings, significantly reducing the feature sizes down to 22 nm and beyond. To achieve such a grating, the surface flatness, the line edge roughness, the transmission efficiency and aspect ratio should be improved significantly. Delachat et al (2015 Nanotechnology 26 108262) develop a full process to fabricate a tungsten diffraction grating on an ultrathin silicon membrane with higher aspect ratio up to 8.75 that met all the aforementioned requirements for extreme ultraviolet lithography. This process is fully compatible with standard industrial extreme ultraviolet lithography.

  16. Recent temperature extremes at high northern latitudes unprecedented in the past 600 years.

    PubMed

    Tingley, Martin P; Huybers, Peter

    2013-04-11

    Recently observed extreme temperatures at high northern latitudes are rare by definition, making the longer time span afforded by climate proxies important for assessing how the frequency of such extremes may be changing. Previous reconstructions of past temperature variability have demonstrated that recent warmth is anomalous relative to preceding centuries or millennia, but extreme events can be more thoroughly evaluated using a spatially resolved approach that provides an ensemble of possible temperature histories. Here, using a hierarchical Bayesian analysis of instrumental, tree-ring, ice-core and lake-sediment records, we show that the magnitude and frequency of recent warm temperature extremes at high northern latitudes are unprecedented in the past 600 years. The summers of 2005, 2007, 2010 and 2011 were warmer than those of all prior years back to 1400 (probability P > 0.95), in terms of the spatial average. The summer of 2010 was the warmest in the previous 600 years in western Russia (P > 0.99) and probably the warmest in western Greenland and the Canadian Arctic as well (P > 0.90). These and other recent extremes greatly exceed those expected from a stationary climate, but can be understood as resulting from constant space-time variability about an increased mean temperature. PMID:23579678

  17. A genome-wide analysis of putative functional and exonic variation associated with extremely high intelligence

    PubMed Central

    Kadeva, Neli; Miller, Mike B.; Iacono, William G.; McGue, Matt; Stergiakouli, Evie; Davey Smith, George; Putallaz, Martha; Lubinski, David; Meaburn, Emma L.; Plomin, Robert; Simpson, Michael A.

    2015-01-01

    Although individual differences in intelligence (general cognitive ability) are highly heritable, molecular genetic analyses to date have had limited success in identifying specific loci responsible for its heritability. The present study is the first to investigate exome variation in individuals of extremely high intelligence. Under the quantitative genetic model, sampling from the high extreme of the distribution should provide increased power to detect associations. We therefore performed a case-control association analysis with 1 409 individuals drawn from the top 0.0003 (IQ > 170) of the population distribution of intelligence and 3 253 unselected population-based controls. Our analysis focused on putative functional exonic variants assayed on the Illumina Human Exome BeadChip. We did not observe any individual protein-altering variants that are reproducibly associated with extremely high intelligence and within the entire distribution of intelligence. Moreover, no significant associations were found for multiple rare alleles within individual genes. However, analyses using genome-wide similarity between unrelated individuals (Genome-wide Complex Trait Analysis) indicate that the genotyped functional protein-altering variation yields a heritability estimate of 17.4% (SE 1.7%) based on a liability model. In addition, investigation of nominally significant associations revealed fewer rare alleles associated with extremely high intelligence than would be expected under the null hypothesis. This observation is consistent with the hypothesis that rare functional alleles are more frequently detrimental than beneficial to intelligence. PMID:26239293

  18. A genome-wide analysis of putative functional and exonic variation associated with extremely high intelligence.

    PubMed

    Spain, S L; Pedroso, I; Kadeva, N; Miller, M B; Iacono, W G; McGue, M; Stergiakouli, E; Smith, G D; Putallaz, M; Lubinski, D; Meaburn, E L; Plomin, R; Simpson, M A

    2016-08-01

    Although individual differences in intelligence (general cognitive ability) are highly heritable, molecular genetic analyses to date have had limited success in identifying specific loci responsible for its heritability. This study is the first to investigate exome variation in individuals of extremely high intelligence. Under the quantitative genetic model, sampling from the high extreme of the distribution should provide increased power to detect associations. We therefore performed a case-control association analysis with 1409 individuals drawn from the top 0.0003 (IQ >170) of the population distribution of intelligence and 3253 unselected population-based controls. Our analysis focused on putative functional exonic variants assayed on the Illumina HumanExome BeadChip. We did not observe any individual protein-altering variants that are reproducibly associated with extremely high intelligence and within the entire distribution of intelligence. Moreover, no significant associations were found for multiple rare alleles within individual genes. However, analyses using genome-wide similarity between unrelated individuals (genome-wide complex trait analysis) indicate that the genotyped functional protein-altering variation yields a heritability estimate of 17.4% (s.e. 1.7%) based on a liability model. In addition, investigation of nominally significant associations revealed fewer rare alleles associated with extremely high intelligence than would be expected under the null hypothesis. This observation is consistent with the hypothesis that rare functional alleles are more frequently detrimental than beneficial to intelligence. PMID:26239293

  19. Extremely high energy neutrinos in six years of IceCube data

    NASA Astrophysics Data System (ADS)

    Ishihara, Aya; IceCube Collaboration

    2016-05-01

    The IceCube neutrino observatory is capable of detecting ultra-high-energy cosmic neutrinos even above PeV - EeV energies. These extremely high energy (EHE) neutrinos (≥ 10 PeV) are produced from interactions of the most energetic cosmic rays (≥ 1 EeV) and ambient photons/matter in the sources or diffuse photon fields such as the cosmic microwave background. Therefore, observations of these EHE neutrinos can be used to probe the origin of the highest energy cosmic rays with energies extending up to 100 EeV. We present the results of an updated analysis of the EHE neutrino sample with energies greater than ~ 1 PeV in 6 years of IceCube data (3 years of partially completed IceCube data (2008-2011) and 3 years of completed IceCube data (2011-2014)). While one event depositing an energy of 770±200 TeV was observed, it is incompatible with a hypothesis of cosmogenic origin. The resultant improvement in the upper limit corresponds to a factor of more than 2.5 from the previous study of two years of data from the nearly completed IceCube detector. Our limits disfavor the parameter space of sources of ultra-high-energy cosmic rays for which the cosmological evolution is stronger than the star formation rate, where the source candidate classes of active galactic nuclei (AGN) and gamma-ray bursts (GRB) belong, assuming the cosmic-ray composition is proton dominated. Results from a 7-year data analysis by adding another year’s worth of data to the current sample are also anticipated soon.

  20. Current Perspectives in High Energy Astrophysics

    NASA Technical Reports Server (NTRS)

    Ormes, Jonathan F. (Editor)

    1996-01-01

    High energy astrophysics is a space-age discipline that has taken a quantum leap forward in the 1990s. The observables are photons and particles that are unable to penetrate the atmosphere and can only be observed from space or very high altitude balloons. The lectures presented as chapters of this book are based on the results from the Compton Gamma-Ray Observatory (CGRO) and Advanced Satellite for Cosmology and Astrophysics (ASCA) missions to which the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center made significant hardware contributions. These missions study emissions from very hot plasmas, nuclear processes, and high energy particle interactions in space. Results to be discussed include gamma-ray beaming from active galactic nuclei (AGN), gamma-ray emission from pulsars, radioactive elements in the interstellar medium, X-ray emission from clusters of galaxies, and the progress being made to unravel the gamma-ray burst mystery. The recently launched X-ray Timing Explorer (XTE) and prospects for upcoming Astro-E and Advanced X-ray Astronomy Satellite (AXAF) missions are also discussed.

  1. High-resolution analysis of 1 day extreme precipitation in Sicily

    NASA Astrophysics Data System (ADS)

    Maugeri, M.; Brunetti, M.; Garzoglio, M.; Simolo, C.

    2015-04-01

    Sicily, the major Mediterranean island, experienced several exceptional precipitation episodes and floods during the last century, with dramatic consequences on human life and environment. A long term, rational planning of urban development is mandatory for protecting population and avoiding huge economic losses in the future. This requires a deep knowledge of the distributional features of extreme precipitation over the complex territory of Sicily. In the present study, we address this issue, and attempt a detailed investigation of observed 1-day precipitation extremes and their frequency distribution, based on a dense data-set of high-quality, homogenized station records in 1921-2005. We extrapolate very high quantiles (return levels) corresponding to 10-, 50- and 100-year return periods, as predicted by a generalized extreme value distribution. Return level estimates are produced on a regular high-resolution grid (30 arcsec) using a variant of regional frequency analysis combined with regression techniques. Results clearly reflect the complexity of this region, and make evident the high vulnerability of its eastern and northeastern parts as those prone to the most intense and potentially damaging events. This analysis thus provides an operational tool for extreme precipitation risk assessment and, at the same time, is an useful basis for validation and downscaling of regional climate models.

  2. Design, fabrication, and characterization of high-efficiency extreme ultraviolet diffusers

    SciTech Connect

    Naulleau, Patrick P.; Liddle, J. Alexander; Salmassi, Farhad; Anderson, Erik H.; Gullikson, Eric M.

    2004-02-19

    As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such example is the diffuser often implemented with ordinary ground glass in the visible light regime. Here we demonstrate the fabrication of reflective EUV diffusers with high efficiency within a controllable bandwidth. Using these techniques we have fabricated diffusers with efficiencies exceeding 10% within a moderate angular single-sided bandwidth of approximately 0.06 radians.

  3. High current density cathode for electrorefining in molten electrolyte

    DOEpatents

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  4. Observation of extreme ultraviolet transitions in highly charged Ba16+ to Ba23+ ions with electron beam ion trap

    NASA Astrophysics Data System (ADS)

    Ali, S.; Shimizu, E.; Nakamura, N.

    2016-03-01

    We have investigated extreme ultraviolet emission from highly charged barium using a compact electron beam ion trap at the Tokyo EBIT laboratory. The spectra were recorded for several beam energies ranging from 440 to 740 eV, while keeping the electron beam current constant at 10 mA. Radiation from charge states Zr-like Ba16+ to As-like Ba23+ were recorded and identified by varying the electron beam energy across the ionization thresholds and comparing with calculated results. The calculations were performed with a detailed relativistic configuration interaction approach using the Flexible Atomic Code. Several new lines belonging to electric dipole transitions were observed and identified.

  5. High-resolution Sonographic Measurements of Lower Extremity Bursae in Chinese Healthy Young Men

    PubMed Central

    Gao, Yong-Yan; Wu, Chi-Qiu; Liu, Wei-Xing; Zhang, Lei; Li, Chun-Ling

    2016-01-01

    Background: Lower extremity bursae are very vulnerable to injury during strenuous physical exercises. Understanding the imaging characteristics of normal bursae is essential for early diagnosis of morphological abnormalities. Therefore, we evaluated the normal range of lower extremity bursae in healthy young men using high-resolution ultrasound (HR-US) imaging. Methods: Bursae in the lower extremities were examined by HR-US in 290 Chinese healthy young men with a median age of 18 years (range, 18–23 years). The bilateral suprapatellar bursa (SPB), deep infrapatellar bursa (DIPB), popliteal bursa (PB), and retrocalcaneal bursa (RCB) were imaged and measured for analysis. Results: The HR-US identification rates of the SPB, DIPB, PB, and RCB were 89.0% (517/580), 55.0% (319/580), 29.4% (171/580), and 49.5% (287/580), respectively. With the assumption that the bursae were normal in 95% of the study participants, the length and width values at the maximal cross-section of the SPB, DIPB, PB, and RCB were ≤18.00 and 6.09 mm, 8.10 and 2.11 mm, 7.67 and 3.93 mm, and 7.82 and 2.04 mm, respectively. Conclusions: Using HR-US imaging, we were able to analyze lower extremity bursae with high detection rates in healthy young men. The normal ranges of lower extremity bursa dimensions in healthy young men measured by HR-US in this study could be used as reference values for evaluation of bursa abnormalities in the lower extremity. PMID:26831233

  6. Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation.

    PubMed

    Plötzing, M; Adam, R; Weier, C; Plucinski, L; Eich, S; Emmerich, S; Rollinger, M; Aeschlimann, M; Mathias, S; Schneider, C M

    2016-04-01

    The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales. PMID:27131684

  7. XMM-Newton analysis of a newly discovered, extremely X-ray luminous galaxy cluster at high redshift

    NASA Astrophysics Data System (ADS)

    Thoelken, S.; Schrabback, T.

    2016-06-01

    Galaxy clusters, the largest virialized structures in the universe, provide an excellent method to test cosmology on large scales. The galaxy cluster mass function as a function of redshift is a key tool to determine the fundamental cosmological parameters and especially measurements at high redshifts can e.g. provide constraints on dark energy. The fgas test as a direct cosmological probe is of special importance. Therefore, relaxed galaxy clusters at high redshifts are needed but these objects are considered to be extremely rare in current structure formation models. Here we present first results from an XMM-Newton analysis of an extremely X-ray luminous, newly discovered and potentially cool core cluster at a redshift of z=0.9. We carefully account for background emission and PSF effects and model the cluster emission in three radial bins. Our preliminary results suggest that this cluster is indeed a good candidate for a cool core cluster and thus potentially of extreme value for cosmology.

  8. Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation

    NASA Astrophysics Data System (ADS)

    Plötzing, M.; Adam, R.; Weier, C.; Plucinski, L.; Eich, S.; Emmerich, S.; Rollinger, M.; Aeschlimann, M.; Mathias, S.; Schneider, C. M.

    2016-04-01

    The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.

  9. An extremely high-altitude plume seen at Mars' morning terminator

    NASA Astrophysics Data System (ADS)

    Sánchez-Lavega, A.; García Muñoz, A.; García-Melendo, E.; Pérez-Hoyos, S.; Gómez-Forrellad, J. M.; Pellier, C.; Delcroix, M.; López-Valverde, M. A.; González-Galindo, F.; Jaeschke, W.; Parker, D.; Phillips, J.; Peach, D.

    2015-02-01

    The Martian limb (that is, the observed `edge' of the planet) represents a unique window into the complex atmospheric phenomena occurring there. Clouds of ice crystals (CO2 ice or H2O ice) have been observed numerous times by spacecraft and ground-based telescopes, showing that clouds are typically layered and always confined below an altitude of 100 kilometres suspended dust has also been detected at altitudes up to 60 kilometres during major dust storms. Highly concentrated and localized patches of auroral emission controlled by magnetic field anomalies in the crust have been observed at an altitude of 130 kilometres. Here we report the occurrence in March and April 2012 of two bright, extremely high-altitude plumes at the Martian terminator (the day-night boundary) at 200 to 250 kilometres or more above the surface, and thus well into the ionosphere and the exosphere. They were spotted at a longitude of about 195° west, a latitude of about -45° (at Terra Cimmeria), extended about 500 to 1,000 kilometres in both the north-south and east-west directions, and lasted for about 10 days. The features exhibited day-to-day variability, and were seen at the morning terminator but not at the evening limb, which indicates rapid evolution in less than 10 hours and a cyclic behaviour. We used photometric measurements to explore two possible scenarios and investigate their nature. For particles reflecting solar radiation, clouds of CO2-ice or H2O-ice particles with an effective radius of 0.1 micrometres are favoured over dust. Alternatively, the plume could arise from auroral emission, of a brightness more than 1,000 times that of the Earth's aurora, over a region with a strong magnetic anomaly where aurorae have previously been detected. Importantly, both explanations defy our current understanding of Mars' upper atmosphere.

  10. Parasitic slow extraction of extremely weak beam from a high-intensity proton rapid cycling synchrotron

    NASA Astrophysics Data System (ADS)

    Zou, Ye; Tang, Jingyu; Yang, Zheng; Jing, Hantao

    2014-02-01

    This paper proposes a novel method to extract extremely weak beam from a high-intensity proton rapid cycling synchrotron (RCS) in the parasitic mode, while maintaining the normal fast extraction. The usual slow extraction method from a synchrotron by employing third-order resonance cannot be applied in a high-intensity RCS due to a very short flat-top at the extraction energy and the strict control on beam loss. The proposed parasitic slow extraction method moves the beam to scrape a scattering foil prior to the fast beam extraction by employing either a local orbit bump or momentum deviation or their combination, so that the halo part of the beam will be scattered. A part of the scattered particles will be extracted from the RCS and guided to the experimental area. The slow extraction process can last about a few milliseconds before the beam is extracted by the fast extraction system. The method has been applied to the RCS of China Spallation Neutron Source. With 1.6 GeV in the extraction energy, 62.5 μA in the average current and 25 Hz in the repetition rate for the RCS, the proton intensity by the slow extraction method can be up to 2×104 protons per cycle or 5×105 protons per second. The extracted beam has also a good time structure of approximately uniform in a spill which is required for many applications such as detector tests. Detailed studies including the scattering effect in the foil, the local orbit bump by the bump magnets and dispersive orbit bump by modifying the RF pattern, the multi-particle simulations by ORBIT and TURTLE codes, and some technical features for the extraction magnets are presented.

  11. An extremely high-altitude plume seen at Mars' morning terminator.

    PubMed

    Sánchez-Lavega, A; Muñoz, A García; García-Melendo, E; Pérez-Hoyos, S; Gómez-Forrellad, J M; Pellier, C; Delcroix, M; López-Valverde, M A; González-Galindo, F; Jaeschke, W; Parker, D; Phillips, J; Peach, D

    2015-02-26

    The Martian limb (that is, the observed 'edge' of the planet) represents a unique window into the complex atmospheric phenomena occurring there. Clouds of ice crystals (CO2 ice or H2O ice) have been observed numerous times by spacecraft and ground-based telescopes, showing that clouds are typically layered and always confined below an altitude of 100 kilometres; suspended dust has also been detected at altitudes up to 60 kilometres during major dust storms. Highly concentrated and localized patches of auroral emission controlled by magnetic field anomalies in the crust have been observed at an altitude of 130 kilometres. Here we report the occurrence in March and April 2012 of two bright, extremely high-altitude plumes at the Martian terminator (the day-night boundary) at 200 to 250 kilometres or more above the surface, and thus well into the ionosphere and the exosphere. They were spotted at a longitude of about 195° west, a latitude of about -45° (at Terra Cimmeria), extended about 500 to 1,000 kilometres in both the north-south and east-west directions, and lasted for about 10 days. The features exhibited day-to-day variability, and were seen at the morning terminator but not at the evening limb, which indicates rapid evolution in less than 10 hours and a cyclic behaviour. We used photometric measurements to explore two possible scenarios and investigate their nature. For particles reflecting solar radiation, clouds of CO2-ice or H2O-ice particles with an effective radius of 0.1 micrometres are favoured over dust. Alternatively, the plume could arise from auroral emission, of a brightness more than 1,000 times that of the Earth's aurora, over a region with a strong magnetic anomaly where aurorae have previously been detected. Importantly, both explanations defy our current understanding of Mars' upper atmosphere. PMID:25686601

  12. Very high speed optoelectronic functions for extremely high data rate communications between satellites

    NASA Astrophysics Data System (ADS)

    Folcke, Georges; Defrancq, Jean-Marc; Geffroy, Dominique; Roy, Bernard

    1998-05-01

    High data rate communications between satellites request to develop very specific electronic circuits. Very high speed, high current (more than 500 mA peak to peak) and low power consumption laser driver was realized and integrated into a specific low volume and low mass hybrid design. This paper reports also the realization of a complete receiver based on the integration of an Avalanche Photodiode (APD) into a very low noise preamplifier followed by an other hybrid module including a limiter amplifier, a clock recovery and decision circuit. The high voltage DC/DC convertor for the APD is also presented as a third hybrid circuit. Full bit rate is in the range of 622 Mbps. For the receiver, the sensitivity obtained is very closed to the theoretical possibilities. The opto- electronic modules under realization (or realized) are fiber pigtailed, with a single mode fiber on the transmitter side and a multimode fiber on the receiver side which allow their integration into the communication boxes. The present paper gives an overview of the modules development, including the main results, and situates these activities in a more complete realization of optical communication boxes.

  13. Compact submicrosecond, high current generator for wire explosion experiments

    NASA Astrophysics Data System (ADS)

    Aranchuk, L. E.; Chuvatin, A. S.; Larour, J.

    2004-01-01

    The PIAF generator was designed for low total energy and high energy density experiments with liners, X-pinch or fiber Z-pinch loads. These studies are of interest for such applications as surface and material science, microscopy of biological specimens, lithography of x-ray sensitive resists, and x-ray backlighting of pulsed-power plasmas. The generator is based on an RLC circuit that includes six NWL 180 nF-50 kV capacitors that store up to 1.3 kJ. The capacitors are connected in parallel to a single multispark switch designed to operate at atmospheric pressure. The switch allows reaching a time delay between the trigger pulse and the current pulse of less than 80 ns and has jitter of 6 ns. The total inductance without a load compartment was optimized to be as low as 16 nH, which leads to extremely low impedance of ˜0.12 Ω. A 40 kV initial voltage provides 250 kA maximum current in a 6 nH inductive load with a 180 ns current rise time. PIAF has dimensions of 660×660×490 mm and weight of less than 100 kg, thus manifesting itself as robust, simple to operate, and cost effective. A description of the PIAF generator and the initial experimental results on PIAF with an X-pinch type load are reported. The generator was demonstrated to operate successfully with an X-pinch type load. The experiments first started with investigation of the previously unexplored X-pinch conduction time range, 100 ns-1 μs. A single short radiation pulse was obtained that came from a small, point-like plasma. The following x-ray source characteristics were achieved: typical hot spot size of 50-100 μm, radiation pulse duration of 1.5-2 ns, and radiation yield of about 250-500 mJ in the softer spectral range (hν⩾700 eV) and 50-100 mJ in the harder one (hν⩾1 keV). These results provide the potential for further application of this source, such as use as a backlight diagnostic tool.

  14. REVIEW OF VARIOUS APPROACHES TO ADDRESS HIGH CURRENTS IN SRF ELECTRON LINACS.

    SciTech Connect

    BEN-ZVI, I.

    2005-07-10

    The combination of high-brightness electron sources and high-current SRF Energy Recovery Linacs (ERL) leads to a new emerging technology: High-power, high-brightness electron beams. This technology enables extremely high average power Free-Electron Lasers, a new generation of extreme brightness light sources, electron coolers of high-energy hadron storage rings, polarized electron-hadron colliders of very high luminosity, compact Thomson scattering X-ray sources, terahertz radiation generators and much more. What is typical for many of these applications is the need for very high current, defined here as over 100 mA average current, and high brightness, which is charge dependant, but needs to be in the range of between sub micron up to perhaps 50 microns, usually the lower--the better. Suffice it to say that while there are a number of projects aiming at this level of performance, none is anywhere near it. This work will review the problems associated with the achievement of such performance and the various approaches taken in a number of laboratories around the world to address the issues.

  15. HIGH DYNAMIC-RANGE HIGH SPEED LINAC CURRENT MEASUREMENTS

    SciTech Connect

    Deibele, Craig Edmond; Curry, Douglas E; Dickson, Richard W

    2012-01-01

    It is desired to measure the linac current of a charged particle beam with a consistent accuracy over a dynamic range of over 120 dB. Conventional current transformers suffer from droop, can be susceptible to electromagnetic interference (EMI), and can be bandwidth limited. A novel detector and electronics were designed to maximize dynamic range of about 120 dB and measure rise-times on the order of 10 nanoseconds.

  16. Modeling of high-current devices with explosive electron emission

    NASA Astrophysics Data System (ADS)

    Anishchenko, S. V.; Gurinovich, A. A.

    2014-01-01

    Based on a detailed analysis of explosive electron emission in high-current electronic devices, we formulate a system of equations that describes the expansion of cathode plasma and the generation of high-current electron beams. The system underlies the numerical algorithm for the hybrid code which enables the simulation of the charged particles’ dynamics in high-current vircators with open resonators. Using the Gabor-Morlet transform, we perform a time-frequency analysis of vircator radiation.

  17. Stable superconducting magnet. [high current levels below critical temperature

    NASA Technical Reports Server (NTRS)

    Boom, R. W. (Inventor)

    1967-01-01

    Operation of a superconducting magnet is considered. A method is described for; (1) obtaining a relatively high current in a superconducting magnet positioned in a bath of a gas refrigerant; (2) operating a superconducting magnet at a relatively high current level without training; and (3) operating a superconducting magnet containing a plurality of turns of a niobium zirconium wire at a relatively high current level without training.

  18. Extreme Precipitation: Resolving the Added Value of High-Resolution Physical and Statistical Modeling

    NASA Astrophysics Data System (ADS)

    Hayhoe, K.; Stoner, A. M. K.; Wang, J.; Scott-Fleming, I.; Abeysundara, S.; Kotamarthi, V. R.

    2014-12-01

    Human-induced climate change is altering the risk of many types of weather extremes, including the frequency and/or severity of heavy precipitation events. The basic science connecting global warming to more frequent heavy precipitation is relative straightforward. It is far more challenging, however, to predict how climate change will affect the magnitude and frequency of these events at the relatively fine spatial scales at which the impacts of extreme rainfall, snow storms, and flooding are typically characterized. Using a case study based on a set of geographically distributed long-term weather stations located at Dept. of Defense installations across the U.S., we explore the individual and combined contributions of high-resolution regional climate modeling (WRF), station-based statistical downscaling (ARRM), extreme value distributions (GEV), and the use of global mean temperature-based thresholds rather than time slices (an approach that is illustrated Figure 1) to resolve observed trends and narrow the envelope of projected future change. All projections and analyses are based on the CESM1-MOAR simulation driven by the higher RCP 8.5 scenario, a consistency specifically introduced into the experiment in order to better resolve the strengths and limitations of each method in understanding extreme precipitation trends. Each of these approaches provides clear added value when compared to direct output from the global climate model. We also find that the ability to refine global model output using high-resolution physical modeling, statistics, and observations can all prove useful at different geographic locations and for different parts of the distribution. However, the primary conclusion of this analysis is the utility of combining multiple physical and statistical modeling and analysis approaches when addressing issues such as extreme precipitation that occur at the tails of the distribution.

  19. High-resolution analysis of 1 day extreme precipitation in Sicily

    NASA Astrophysics Data System (ADS)

    Maugeri, Maurizio; Brunetti, Michele; Garzoglio, Mistral; Simolo, Claudia; Bertolini, Andrea

    2016-04-01

    Sicily, the major Mediterranean island, experienced several exceptional precipitation episodes and floods during the last century, with serious damage to human life and environment. A long term, rational planning of urban development is indispensable to protect the population and to avoid huge economic losses in the future. This requires a thorough knowledge of the distributional features of extreme precipitation over the complex territory of Sicily. In this study, we perform a detailed investigation of observed 1-day precipitation extremes and their frequency distribution, based on a dense data-set of high-quality, homogenized station records in 1921-2005. We estimate very high quantiles (return levels) corresponding to 10-, 50- and 100-yr return periods, as predicted by a generalized extreme value distribution. Return level estimates are produced on a regular high-resolution grid (30 arcsec) using a variant of regional frequency analysis combined with regression techniques. Results clearly reflect the complexity of this region, and show the high vulnerability of its eastern and northeastern parts as those prone to the most intense and potentially damaging events.

  20. High-resolution analysis of 1 day extreme precipitation in Sicily

    NASA Astrophysics Data System (ADS)

    Maugeri, M.; Brunetti, M.; Garzoglio, M.; Simolo, C.

    2015-10-01

    Sicily, a major Mediterranean island, has experienced several exceptional precipitation episodes and floods during the last century, with serious damage to human life and the environment. Long-term, rational planning of urban development is indispensable to protect the population and to avoid huge economic losses in the future. This requires a thorough knowledge of the distributional features of extreme precipitation over the complex territory of Sicily. In this study, we perform a detailed investigation of observed 1 day precipitation extremes and their frequency distribution, based on a dense data set of high-quality, homogenized station records in 1921-2005. We estimate very high quantiles (return levels) corresponding to 10-, 50- and 100-year return periods, as predicted by a generalized extreme value distribution. Return level estimates are produced on a regular high-resolution grid (30 arcsec) using a variant of regional frequency analysis combined with regression techniques. Results clearly reflect the complexity of this region, and show the high vulnerability of its eastern and northeastern parts as those prone to the most intense and potentially damaging events.

  1. Extreme cosmic ray dominated regions: a new paradigm for high star formation density events in the Universe

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Padeli P.; Thi, Wing-Fai; Miniati, Francesco; Viti, Serena

    2011-06-01

    We examine in detail the recent proposal that extreme cosmic ray dominated regions (CRDRs) characterize the interstellar medium of galaxies during events of high-density star formation, fundamentally altering its initial conditions (Papadopoulos 2010). Solving the coupled chemical and thermal state equations for dense UV-shielded gas reveals that the large CR energy densities in such systems [UCR ˜ few × (103-104) UCR, Gal] will indeed raise the minimum temperature of this phase (where the initial conditions of star formation are set) from ˜10 K (as in the Milky Way) to ˜50-100 K. Moreover in such extreme CRDRs the gas temperature remains fully decoupled from that of the dust, with Tkin≫Tdust, even at high densities [n(H2) ˜ 105-106 cm-3], quite unlike CRDRs in the Milky Way where Tk˜Tdust when n(H2) ≳ 105 cm-3. These dramatically different star formation initial conditions will (i) boost the Jeans mass of UV-shielded gas regions by factors of ˜10-100 with respect to those in quiescent or less extreme star-forming systems and (ii) 'erase' the so-called inflection point of the effective equation of state of molecular gas. Both these effects occur across the entire density range of typical molecular clouds, and may represent a new paradigm for all high-density star formation in the Universe, with CRs as the key driving mechanism, operating efficiently even in the high dust extinction environments of compact extreme starbursts. The characteristic mass of young stars will be boosted as a result, naturally yielding a top-heavy stellar initial mass function (IMF) and a bimodal star formation mode (with the occurrence of extreme CRDRs setting the branching point). Such CRDRs will be present in Ultra-Luminous Infrared Galaxies (ULIRGs) and merger-driven gas-rich starbursts across the Universe where large amounts of molecular gas rapidly dissipate towards compact disc configurations where they fuel intense starbursts. In hierarchical galaxy formation models, CR

  2. High-resolution extreme-ultraviolet spectroscopy of potassium using anti-Stokes radiation

    NASA Technical Reports Server (NTRS)

    Rothenberg, J. E.; Young, J. F.; Harris, S. E.

    1981-01-01

    The use of a new extreme-ultraviolet radiation source based on spontaneous anti-Stokes scattering for high-resolution absorption spectroscopy of transition originating from the 3p6 shell of potassium is reported. The region from 546.6 to 536.8 A is scanned at a resolution of about 1.2 Kayser. Within this region, four previously unreported lines are observed.

  3. Generation of high-resolution kagome lattice structures using extreme ultraviolet interference lithography

    NASA Astrophysics Data System (ADS)

    Wang, Li; Terhalle, Bernd; Guzenko, Vitaliy A.; Farhan, Alan; Hojeij, Mohamad; Ekinci, Yasin

    2012-08-01

    High-resolution kagome lattice structures with feature sizes down to the sub-50 nm regime are fabricated using diffraction-based extreme ultraviolet interference lithography. The resulting interference pattern of multiple beams is sensitive to the relative phase of the interfering beams. The precise control of their phases is achieved by precise positioning of transmission diffraction gratings on a mask using a high-end electron beam lithography tool. The presented method may find applications in providing high-resolution and large-area kagome lattice structures for studies on frustrated magnetic systems, photonic crystals, and plasmonics.

  4. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment

    PubMed Central

    Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.

    2015-01-01

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events. PMID:26627576

  5. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment.

    PubMed

    Schoepf, Verena; Stat, Michael; Falter, James L; McCulloch, Malcolm T

    2015-01-01

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events. PMID:26627576

  6. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment

    NASA Astrophysics Data System (ADS)

    Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.

    2015-12-01

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events.

  7. High dimensional spatial modeling of extremes with applications to United States Rainfalls

    NASA Astrophysics Data System (ADS)

    Zhou, Jie

    2007-12-01

    Spatial statistical models are used to predict unobserved variables based on observed variables and to estimate unknown model parameters. Extreme value theory(EVT) is used to study large or small observations from a random phenomenon. Both spatial statistics and extreme value theory have been studied in a lot of areas such as agriculture, finance, industry and environmental science. This dissertation proposes two spatial statistical models which concentrate on non-Gaussian probability densities with general spatial covariance structures. The two models are also applied in analyzing United States Rainfalls and especially, rainfall extremes. When the data set is not too large, the first model is used. The model constructs a generalized linear mixed model(GLMM) which can be considered as an extension of Diggle's model-based geostatistical approach(Diggle et al. 1998). The approach improves conventional kriging with a form of generalized linear mixed structure. As for high dimensional problems, two different methods are established to improve the computational efficiency of Markov Chain Monte Carlo(MCMC) implementation. The first method is based on spectral representation of spatial dependence structures which provides good approximations on each MCMC iteration. The other method embeds high dimensional covariance matrices in matrices with block circulant structures. The eigenvalues and eigenvectors of block circulant matrices can be calculated exactly by Fast Fourier Transforms(FFT). The computational efficiency is gained by transforming the posterior matrices into lower dimensional matrices. This method gives us exact update on each MCMC iteration. Future predictions are also made by keeping spatial dependence structures fixed and using the relationship between present days and future days provided by some Global Climate Model(GCM). The predictions are refined by sampling techniques. Both ways of handling high dimensional covariance matrices are novel to analyze large

  8. Multipulse current source offers low power losses and high reliability

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Pulse current source uses low loss, high reliability, LC circuits to provide the necessary high impedance for magnetic memory cores, frequently used in digital computational equipment. Square-loop reactors replace the semiconductor switches previously used.

  9. Asymmetrically contacted germanium photodiode using a metal-interlayer-semiconductor-metal structure for extremely large dark current suppression.

    PubMed

    Zang, Hwan-Jun; Kim, Gwang-Sik; Park, Gil-Jae; Choi, Yong-Soo; Yu, Hyun-Yong

    2016-08-15

    In this study, we proposed germanium (Ge) metal-interlayer-semiconductor-metal (MISM) photodiodes (PD), with an anode of a metal-interlayer-semiconductor (MIS) contact and a cathode of a metal-semiconductor (MS) contact, to efficiently suppress the dark current of Ge PD. We selected titanium dioxide (TiO2) as an interlayer material for the MIS contact, due to its large valence band offset and negative conduction band offset to Ge. We significantly suppress the dark current of Ge PD by introducing the MISM structure with a TiO2 interlayer, as this enhances the hole Schottky barrier height, and thus acts as a large barrier for holes. In addition, it collects photo-generated carriers without degradation, due to its negative conduction band offset to Ge. This reduces the dark current of Ge MISM PDs by ×8000 for 7-nm-thick TiO2 interlayer, while its photo current is still comparable to that of Ge metal-semiconductor-metal (MSM) PDs. Furthermore, the proposed Ge PD shows ×6,600 improvement of the normalized photo-to-dark-current ratio (NPDR) at a wavelength of 1.55 μm. The proposed Ge MISM PD shows considerable promise for low power and high sensitivity Ge-based optoelectronic applications. PMID:27519063

  10. Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs.

    PubMed

    Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

    2016-01-01

    Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10-13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs. PMID:27355212

  11. Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs

    PubMed Central

    Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

    2016-01-01

    Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10−13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs. PMID:27355212

  12. Impact of the extreme 2009 wildfire Victoria the wettability of naturally highly water repellent soils

    NASA Astrophysics Data System (ADS)

    Doerr, Stefan H.; Shakesby, Richard A.; Sheridan, Gary J.; Lane, Patrick Nj; Smith, Hugh G.; Bell, Tina; Blake, William H.

    2010-05-01

    The recent catastrophic wildfires near Melbourne, which peaked on Feb. 7 2009, burned ca 400,000 ha and caused the tragic loss of 173 people. They occurred during unprecedented extreme fire weather where dry northerly winds gusting up to 100 km/h coincided with the highest temperatures ever recorded in this region. These conditions, combined with the very high biomass of mature eucalypt forests, very low fuel moisture conditions and steep slopes, generated extreme burning conditions. A rapid response project was launched under the NERC Urgency Scheme aimed at determining the effects of this extreme event on soil properties. Three replicate sites each were sampled for extremely high burn severity, high burn severity and unburnt control terrain, within mature mixed-species eucalypt forests near Marysville in April 2009. Ash and surface soil (0-2.5 cm and 2.5-5 cm) were collected at 20 sample grid points at each site. Here we report on outcomes from Water Drop Penetration Time (WDPT) tests carried out on soil samples to determine the impact of this extreme event on the wettability of a naturally highly water repellent soil. Field assessment suggested that the impact of this extreme wildfire on the soil was less than might be supposed given the extreme burn severity (indicated by the complete elimination of the ground vegetation). This was confirmed by the laboratory results. No major difference in WDPT was detected between (i) burned and control samples, and (ii) between surface and subsurface WDPT patterns, indicating that soil temperatures in the top 0-2.5 cm did not exceed ~200° C. Seedling germination in burned soil was reduced by at least 2/3 compared to the control samples, however, this reduction is indicative an only modest heat input into the soil. The limited heat input into the soil stands in stark contrast to the extreme burn severity (based on vegetation destruction parameters). We speculate that limited soil heating resulted perhaps from the unusually

  13. Effects of high frequency current in welding aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  14. Dynamics of laser-guided alternating current high voltage discharges

    NASA Astrophysics Data System (ADS)

    Daigle, J.-F.; Théberge, F.; Lassonde, P.; Kieffer, J.-C.; Fujii, T.; Fortin, J.; Châteauneuf, M.; Dubois, J.

    2013-10-01

    The dynamics of laser-guided alternating current high voltage discharges are characterized using a streak camera. Laser filaments were used to trigger and guide the discharges produced by a commercial Tesla coil. The streaking images revealed that the dynamics of the guided alternating current high voltage corona are different from that of a direct current source. The measured effective corona velocity and the absence of leader streamers confirmed that it evolves in a pure leader regime.

  15. A Superconducting transformer system for high current cable testing

    SciTech Connect

    Godeke, A.; Dietderich, D. R.; Joseph, J. M.; Lizarazo, J.; Prestemon, S. O.; Miller, G.; Weijers, H. W.

    2010-02-15

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10 464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  16. A superconducting transformer system for high current cable testing.

    PubMed

    Godeke, A; Dietderich, D R; Joseph, J M; Lizarazo, J; Prestemon, S O; Miller, G; Weijers, H W

    2010-03-01

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10,464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples. PMID:20370213

  17. HadISD: global data for studying extremes in high resolution

    NASA Astrophysics Data System (ADS)

    Dunn, Robert; Willett, Kate; Thorne, Peter; Woolley, Emma; Parker, David; Durre, Imke; Dai, Aiguo; Vose, Russ; Mead, Naomi; Lott, Fraser

    2013-04-01

    The Met Office Hadley Centre has recently released v1.0 of the new station dataset, HadISD. It contains over 6000 stations with near-surface temperature, dewpoint and sea-level pressure data, along with cloud cover, wind speed and direction. These variables are key to characterising extreme meteorological events with human impacts such as storms and heat waves. The data have been quality controlled using an automated suite of tests, which addresses many known issues with observational data, including individual and clustered outliers, repeated and frequently occurring values. These tests have been combined with buddy checks against neighbouring stations, in an objective, reproducible and consistent manner. Here we introduce our new product which we plan to update on a yearly basis, describing our methodological choices and validation. We will also outline our plans for homogenising this sub-daily data along with some scientific applications of this dataset to recent extremes at high time resolution.

  18. Extreme hydrophobicity and omniphilicity of high-aspect-ratio silicon structures

    NASA Astrophysics Data System (ADS)

    Kwak, Moon Kyu; Park, Cheol Woo; Hwang, Kwang-Il; Park, Choon Man; Jeong, Hoon Eui; Choi, Jun Ho

    2015-03-01

    We present an application of high-aspect-ratio (high-AR) silicon structures (black silicon) with high water repellency and good wettability by oils and solvents. The fabrication of black silicon consists of a deep reactive-ion etching process for extremely-high-AR silicon structures and surface treatment with C4F8 gas. Such high-AR structures were found to be highly resistant against wetting by water, but they also have good wetting characteristics with respect to certain liquids such as ethanol, hexane and mineral oil. To determine the relationship between the AR of nanostructures and wetting selectivity, four different black silicon samples with different pattern heights were used. The static contact angles of various liquid were measured for the analysis of wetting properties of the four black silicon samples. To explore feasible applications, ethanol-water separation was performed as a miniaturized experimental simulation of environmental remediation.

  19. Evolution of laser-produced Sn extreme ultraviolet source diameter for high-brightness source

    SciTech Connect

    Roy, Amitava E-mail: aroy@barc.gov.in; Arai, Goki; Hara, Hiroyuki; Higashiguchi, Takeshi; Ohashi, Hayato; Sunahara, Atsushi; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Miura, Taisuke; Mocek, Tomas; Endo, Akira

    2014-08-18

    We have investigated the effect of irradiation of solid Sn targets with laser pulses of sub-ns duration and sub-mJ energy on the diameter of the extreme ultraviolet (EUV) emitting region and source conversion efficiency. It was found that an in-band EUV source diameter as low as 18 μm was produced due to the short scale length of a plasma produced by a sub-ns laser. Most of the EUV emission occurs in a narrow region with a plasma density close to the critical density value. Such EUV sources are suitable for high brightness and high repetition rate metrology applications.

  20. Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, Brage B.; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif E.; Coulson, Stephen J.; Larsen, Jan Otto; Varpe, Øystein

    2014-11-01

    One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January-February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (˜5-20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

  1. NETL Extreme Drilling Laboratory Studies High Pressure High Temperature Drilling Phenomena

    SciTech Connect

    Lyons, K.D.; Honeygan, S.; Moroz, T

    2007-06-01

    The U.S. Department of Energy’s National Energy Technology Laboratory (NETL) established an Extreme Drilling Lab to engineer effective and efficient drilling technologies viable at depths greater than 20,000 feet. This paper details the challenges of ultra-deep drilling, documents reports of decreased drilling rates as a result of increasing fluid pressure and temperature, and describes NETL’s Research and Development activities. NETL is invested in laboratory-scale physical simulation. Their physical simulator will have capability of circulating drilling fluids at 30,000 psi and 480 °F around a single drill cutter. This simulator will not yet be operational by the planned conference dates; therefore, the results will be limited to identification of leading hypotheses of drilling phenomena and NETL’s test plans to validate or refute such theories. Of particular interest to the Extreme Drilling Lab’s studies are the combinatorial effects of drilling fluid pressure, drilling fluid properties, rock properties, pore pressure, and drilling parameters, such as cutter rotational speed, weight on bit, and hydraulics associated with drilling fluid introduction to the rock-cutter interface. A detailed discussion of how each variable is controlled in a laboratory setting will be part of the conference paper and presentation.

  2. Efficient circuit triggers high-current, high-voltage pulses

    NASA Technical Reports Server (NTRS)

    Green, E. D.

    1964-01-01

    Modified circuit uses diodes to effectively disconnect the charging resistors from the circuit during the discharge cycle. Result is an efficient parallel charging, high voltage pulse modulator with low voltage rating of components.

  3. Hydroclimatology of Extreme Drought and Flood Events in the Northern High Plains, U.S.

    NASA Astrophysics Data System (ADS)

    Smith, K.; Morton, M.; Rico, D.; Mohamad Abadi, A.; Luna, I.; Livneh, B.; Munoz-Arriola, F.

    2014-12-01

    The goal is to illustrate the hydroclimatology of extreme droughts and floods, in the Northern High Plains (NHP). The state of Nebraska has the largest number of irrigated acres in the US by state; thus is exceedingly dependent on the availability of groundwater. Regions along the great Ogallala aquifer have already experienced a dramatic reduction of groundwater with most areas seeing water table drops of 10-50 feet in depth, with several recorded drops of over 100 feet. Finite groundwater resources availability challenges agroecosystems and ecosystem sustainability, leaving productive areas subject to the availability of surface water. However, our understanding on the predictability of extreme events is still limited. Thus our question is: What is the sensitivity of the NHP to extreme droughts and floods? Duration, frequency, and the area of influence of floods and droughts vary but can occur at the same time in different regions or at different times in the same region. Our objective is to (a) identify spatiotemporal patterns of variability of floods and droughts in NHP's land surface hydrology (LSH); and (b) account for the spatiotemporal impacts of deficits and surpluses of water at the basin-scale. The hypothesis is that areas of influence and the associated duration of droughts and floods will be more sensitive to different LSH variables and state variables than to the statistical approaches used to analyze them. To test the present hypothesis we will use gridded observed (precipitation) and simulated LSH variables (runoff, baseflow, and soil moisture) on the Platte River Basin. Precipitation, minimum and maximum temperatures, and wind speed force the Variable infiltration Capacity model at 1/16th degree resolution from 1950 to 2013. Drought indices based on percentiles estimated from Gamma, General Extreme Value, and Gumble distribution functions are estimated using daily observed and simulated variables for the domains and timespans mentioned above

  4. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.

    1998-08-01

    The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (10{sup 9} n/cm{sup 2}/s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin ({approximately} 5 cm iron). However, this approach has an extremely low neutron yield (n/p {approximately} 1.0({minus}6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target {approximately} 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies ({approximately} 2.5 MeV) have a much higher yield (n/p {approximately} 1.0({minus}4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV.

  5. Performance of High Temperature Operational Amplifier, Type LM2904WH, under Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Operation of electronic parts and circuits under extreme temperatures is anticipated in NASA space exploration missions as well as terrestrial applications. Exposure of electronics to extreme temperatures and wide-range thermal swings greatly affects their performance via induced changes in the semiconductor material properties, packaging and interconnects, or due to incompatibility issues between interfaces that result from thermal expansion/contraction mismatch. Electronics that are designed to withstand operation and perform efficiently in extreme temperatures would mitigate risks for failure due to thermal stresses and, therefore, improve system reliability. In addition, they contribute to reducing system size and weight, simplifying its design, and reducing development cost through the elimination of otherwise required thermal control elements for proper ambient operation. A large DC voltage gain (100 dB) operational amplifier with a maximum junction temperature of 150 C was recently introduced by STMicroelectronics [1]. This LM2904WH chip comes in a plastic package and is designed specifically for automotive and industrial control systems. It operates from a single power supply over a wide range of voltages, and it consists of two independent, high gain, internally frequency compensated operational amplifiers. Table I shows some of the device manufacturer s specifications.

  6. From ozone mini-holes and mini-highs towards extreme value theory: New insights from extreme events and non-stationarity

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Staehelin, J.; Maeder, J. A.; Ribatet, M.; Stübi, R.; Weihs, P.; Holawe, F.; Peter, T.; Davison, A. C.

    2009-04-01

    Over the last few decades negative trends in stratospheric ozone have been studied because of the direct link between decreasing stratospheric ozone and increasing surface UV-radiation. Recently a discussion on ozone recovery has begun. Long-term measurements of total ozone extending back earlier than 1958 are limited and only available from a few stations in the northern hemisphere. The world's longest total ozone record is available from Arosa, Switzerland (Staehelin et al., 1998a,b). At this site total ozone measurements have been made since late 1926 through the present day. Within this study (Rieder et al., 2009) new tools from extreme value theory (e.g. Coles, 2001; Ribatet, 2007) are applied to select mathematically well-defined thresholds for extreme low and extreme high total ozone. A heavy-tail focused approach is used by fitting the Generalized Pareto Distribution (GPD) to the Arosa time series. Asymptotic arguments (Pickands, 1975) justify the use of the GPD for modeling exceedances over a sufficiently high (or below a sufficiently low) threshold (Coles, 2001). More precisely, the GPD is the limiting distribution of normalized excesses over a threshold, as the threshold approaches the endpoint of the distribution. In practice, GPD parameters are fitted, to exceedances by maximum likelihood or other methods - such as the probability weighted moments. A preliminary step consists in defining an appropriate threshold for which the asymptotic GPD approximation holds. Suitable tools for threshold selection as the MRL-plot (mean residual life plot) and TC-plot (stability plot) from the POT-package (Ribatet, 2007) are presented. The frequency distribution of extremes in low (termed ELOs) and high (termed EHOs) total ozone and their influence on the long-term changes in total ozone are analyzed. Further it is shown that from the GPD-model the distribution of so-called ozone mini holes (e.g. Bojkov and Balis, 2001) can be precisely estimated and that the

  7. Assessing the impacts of changing precipitation and temperature extremes on the current and future ecohydrology of grassland ecosystems

    NASA Astrophysics Data System (ADS)

    Brunsell, N. A.; Nippert, J. B.; Ocheltree, T.

    2012-12-01

    Extreme weather events have profound impacts on water and carbon cycling. However, events of similar magnitude may have very different impacts depending upon the timing of the event in the phenological cycle. We assess these impacts of extreme daily weather events including precipitation, maximum and minimum temperature using data collected from the Konza Prairie Long Term Ecological Research site in the central U.S. We utilize the long term weather and biomass collection data at the LTER site to examine the historical variability of extreme events and the impacts on annual carbon dynamics. Timescales of interactions between daily weather and fluxes are quantified through a multiscale information theoretic approach. In addition, we quantify the impacts of the timing and magnitude of extreme events through a Critical Climate Period (CCP) analysis. Results indicate a strong sensitivity to spring precipitation and summer temperature. Using six years of eddy covariance data, we can isolate more of the biophysical mechanisms governing the responses to extreme weather events. Of particular interest is the heat wave of July, 2011, where daily maximum temperatures were over 38 C for 24 consecutive days and resulted in drastically reduced above ground carbon allocation than in previous years. In addition, we employ the Agro-BGC model to assess the biophysical processes responsible for determining the response of water and carbon dynamics to extreme weather events. This is done by employing a stochastic weather generator with prescribed changes in annual precipitation and temperature conistent with GCM projections. Developing a more thorough understanding of extreme events and the differential responses due to the timing and magnitude of the events will potentially assist in the mitigation of future climate change.

  8. In situ observation and measurement of composites subjected to extremely high temperature

    NASA Astrophysics Data System (ADS)

    Fang, Xufei; Yu, Helong; Zhang, Guobing; Su, Hengqiang; Tang, Hongxiang; Feng, Xue

    2014-03-01

    In this work, we develop an instrument to study the ablation and oxidation process of materials such as C/SiC (carbon fiber reinforced silicon carbide composites) and ultra-high temperature ceramic in extremely high temperature environment. The instrument is integrated with high speed cameras with filtering lens, infrared thermometers and water vapor generator for image capture, temperature measurement, and humid atmosphere, respectively. The ablation process and thermal shock as well as the temperature on both sides of the specimen can be in situ monitored. The results show clearly the dynamic ablation and liquid oxide flowing. In addition, we develop an algorithm for the post-processing of the captured images to obtain the deformation of the specimens, in order to better understand the behavior of the specimen subjected to high temperature.

  9. EEE - Extreme Energy Events: an astroparticle physics experiment in Italian High Schools

    NASA Astrophysics Data System (ADS)

    Abbrescia, M.; Avanzini, C.; Baldini, L.; Baldini Ferroli, R.; Batignani, G.; Bencivenni, G.; Bossini, E.; Bressan, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; Corvaglia, A.; De Gruttola, D.; De Pasquale, S.; Di Giovanni, A.; D’Incecco, M.; Dreucci, M.; Fabbri, F. L.; Fattibene, E.; Ferrarov, A.; Forster, R.; Frolov, V.; Galeotti, P.; Garbini, M.; Gemme, G.; Gnesi, I.; Grazzi, S.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Maggiora, A.; Maron, G.; Mazziotta, M. N.; Miozzi, S.; Noferini, F.; Nozzoli, F.; Panareo, M.; Panetta, M. P.; Paoletti, R.; Perasso, L.; Pilo, F.; Piragino, G.; Riggi, F.; Righini, G. C.; Rodriguez Rodriguez, A.; Sartorelli, G.; Scapparone, E.; Schioppa, M.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Squarcia, S.; Taiuti, M.; Terreni, G.; Vistoli, M. C.; Votano, L.; Williams, M. C. S.; Zani, S.; Zichichi, A.; Zuyeuski, R.

    2016-05-01

    The Extreme Energy Events project (EEE) is aimed to study Extensive Air Showers (EAS) from primary cosmic rays of more than 1018 eV energy detecting the ground secondary muon component using an array of telescopes with high spatial and time resolution. The second goal of the EEE project is to involve High School teachers and students in this advanced research work and to initiate them in scientific culture: to reach both purposes the telescopes are located inside High School buildings and the detector construction, assembling and monitoring - together with data taking and analysis - are done by researchers from scientific institutions in close collaboration with them. At present there are 42 telescopes in just as many High Schools scattered all over Italy, islands included, plus two at CERN and three in INFN units. We report here some preliminary physics results from the first two common data taking periods together with the outreach impact of the project.

  10. Image-Based Motion Compensation for High-Resolution Extremities Cone-Beam CT

    PubMed Central

    Sisniega, A.; Stayman, J. W.; Cao, Q.; Yorkston, J.; Siewerdsen, J. H.; Zbijewski, W.

    2016-01-01

    Purpose Cone-beam CT (CBCT) of the extremities provides high spatial resolution, but its quantitative accuracy may be challenged by involuntary sub-mm patient motion that cannot be eliminated with simple means of external immobilization. We investigate a two-step iterative motion compensation based on a multi-component metric of image sharpness. Methods Motion is considered with respect to locally rigid motion within a particular region of interest, and the method supports application to multiple locally rigid regions. Motion is estimated by maximizing a cost function with three components: a gradient metric encouraging image sharpness, an entropy term that favors high contrast and penalizes streaks, and a penalty term encouraging smooth motion. Motion compensation involved initial coarse estimation of gross motion followed by estimation of fine-scale displacements using high resolution reconstructions. The method was evaluated in simulations with synthetic motion (1–4 mm) applied to a wrist volume obtained on a CMOS-based CBCT testbench. Structural similarity index (SSIM) quantified the agreement between motion-compensated and static data. The algorithm was also tested on a motion contaminated patient scan from dedicated extremities CBCT. Results Excellent correction was achieved for the investigated range of displacements, indicated by good visual agreement with the static data. 10–15% improvement in SSIM was attained for 2–4 mm motions. The compensation was robust against increasing motion (4% decrease in SSIM across the investigated range, compared to 14% with no compensation). Consistent performance was achieved across a range of noise levels. Significant mitigation of artifacts was shown in patient data. Conclusion The results indicate feasibility of image-based motion correction in extremities CBCT without the need for a priori motion models, external trackers, or fiducials. PMID:27346909

  11. Image-based motion compensation for high-resolution extremities cone-beam CT

    NASA Astrophysics Data System (ADS)

    Sisniega, A.; Stayman, J. W.; Cao, Q.; Yorkston, J.; Siewerdsen, J. H.; Zbijewski, W.

    2016-03-01

    Purpose: Cone-beam CT (CBCT) of the extremities provides high spatial resolution, but its quantitative accuracy may be challenged by involuntary sub-mm patient motion that cannot be eliminated with simple means of external immobilization. We investigate a two-step iterative motion compensation based on a multi-component metric of image sharpness. Methods: Motion is considered with respect to locally rigid motion within a particular region of interest, and the method supports application to multiple locally rigid regions. Motion is estimated by maximizing a cost function with three components: a gradient metric encouraging image sharpness, an entropy term that favors high contrast and penalizes streaks, and a penalty term encouraging smooth motion. Motion compensation involved initial coarse estimation of gross motion followed by estimation of fine-scale displacements using high resolution reconstructions. The method was evaluated in simulations with synthetic motion (1-4 mm) applied to a wrist volume obtained on a CMOS-based CBCT testbench. Structural similarity index (SSIM) quantified the agreement between motion-compensated and static data. The algorithm was also tested on a motion contaminated patient scan from dedicated extremities CBCT. Results: Excellent correction was achieved for the investigated range of displacements, indicated by good visual agreement with the static data. 10-15% improvement in SSIM was attained for 2-4 mm motions. The compensation was robust against increasing motion (4% decrease in SSIM across the investigated range, compared to 14% with no compensation). Consistent performance was achieved across a range of noise levels. Significant mitigation of artifacts was shown in patient data. Conclusion: The results indicate feasibility of image-based motion correction in extremities CBCT without the need for a priori motion models, external trackers, or fiducials.

  12. Development of Large Current High Precision Pulse Power Supply

    NASA Astrophysics Data System (ADS)

    Takayanagi, Tomohiro; Koseki, Shoichiro; Kubo, Hiroshi; Katoh, Shuji; Ogawa, Shinichi

    JAEA and KEK are jointly constructing a high intensity proton accelerator project J-PARC. Its main accelerator is 3GeV synchrotron. Its injection bump magnets, especially horizontal paint bump magnets, are excited by large pulse currents. Their rated currents are over 10kA and pulse widths are about 1ms. Tracking errors are required to be less than 1%. Multiple connected two-quadrant IGBT choppers are adopted for their power supplies. Their output currents are controlled by feedback control with minor loop voltage control (m-AVR). When output current of a chopper intermits at small current, its output voltage rises up and current control becomes difficult. In this paper response of m-AVR and output voltage characteristics at current intermittent region are studied and an improved control scheme is proposed. The performance is confirmed by a test.

  13. Type II/1 Superconductivity with Extremely High Hc3 in Noncentrosymmetric LaRhSi3

    NASA Astrophysics Data System (ADS)

    Kimura, Noriaki; Kabeya, Noriyuki; Saitoh, Kohsuke; Satoh, Kazunori; Ogi, Hajime; Ohsaki, Kohki; Aoki, Haruyoshi

    2016-02-01

    We report the specific heat and ac magnetic susceptibility of noncentrosymmetric superconductor LaRhSi3. A first-order superconducting transition is observed in specific heat C under different magnetic field values. The C(T) values in zero-field-cooling and field-cooling processes become different at a magnetic field between 20 and 130 Oe. These results suggest that conversion from type-I to type-II/1 superconductivity is realized in LaRhSi3. The ac susceptibility indicates that surface superconductivity with an extremely high limiting field occurs probably due to the conversion temperature.

  14. Uterine choriocarcinoma accompanied by an extremely high human chorionic gonadotropin level and thyrotoxicosis.

    PubMed

    Hsieh, Tsung-Ying; Hsu, Keng-Fu; Kuo, Pao-Lin; Huang, Soon-Cen

    2008-04-01

    The conventional treatments given to a 24-year-old woman with metastatic uterine choriocarcinoma and clinical and biochemical thyrotoxicosis did not appear to have any effect, probably due to an extremely high serum human chorionic gonadotropin (hCG) level which was up to 11,910,000 mIU/mL, and were initially underscored in light of the 'high-dose hook effect'. To our knowledge, no extremely high hCG level in a uterine choriocarcinoma patient has been reported in the literature. Her decapacitating symptoms subsided after the first course of chemotherapy by etoposide, methotrexate, and actinomycin D-cyclophosphamide and vincristine (EMA-CO) regimen. The serum hCG level, which reflects the quantification of host tumor burden, returned to the reference range after the fifth course of chemotherapy and the thyroid function reached euthyroid status before the third course of chemotherapy; two final courses were administered after the hCG level became undetectable. Two years after remission of disease, the patient experienced a normal pregnancy, and a term baby girl was delivered vaginally. No recurrence of uterine choriocarcinoma has been noted for 7 years. PMID:18412797

  15. Generation of bright phase-matched circularly-polarized extreme ultraviolet high harmonics

    NASA Astrophysics Data System (ADS)

    Kfir, Ofer; Grychtol, Patrik; Turgut, Emrah; Knut, Ronny; Zusin, Dmitriy; Popmintchev, Dimitar; Popmintchev, Tenio; Nembach, Hans; Shaw, Justin M.; Fleischer, Avner; Kapteyn, Henry; Murnane, Margaret; Cohen, Oren

    2015-02-01

    Circularly-polarized extreme ultraviolet and X-ray radiation is useful for analysing the structural, electronic and magnetic properties of materials. To date, such radiation has only been available at large-scale X-ray facilities such as synchrotrons. Here, we demonstrate the first bright, phase-matched, extreme ultraviolet circularly-polarized high harmonics source. The harmonics are emitted when bi-chromatic counter-rotating circularly-polarized laser pulses field-ionize a gas in a hollow-core waveguide. We use this new light source for magnetic circular dichroism measurements at the M-shell absorption edges of Co. We show that phase-matching of circularly-polarized harmonics is unique and robust, producing a photon flux comparable to linearly polarized high harmonic sources. This work represents a critical advance towards the development of table-top systems for element-specific imaging and spectroscopy of multiple elements simultaneously in magnetic and other chiral media with very high spatial and temporal resolution.

  16. High-performance soft-tissue imaging in extremity cone-beam CT

    NASA Astrophysics Data System (ADS)

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Muhit, A.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2014-03-01

    Purpose: Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. Methods: The accelerated MC scatter correction involved fast MC simulation with low number of photons implemented on a GPU (107 photons/sec), followed by Gaussian kernel smoothing in the detector plane and across projection angles. PL reconstructions were investigated for reduction of imaging dose for projections acquired at ~2 mGy. Results: The rapid scatter estimation yielded root-mean-squared-errors of scatter projections of ~15% of peak scatter intensity for 5ṡ106 photons/projection (runtime ~0.5 sec/projection) and 25% improvement in fat-muscle contrast in reconstructions of a cadaveric knee. PL reconstruction largely restored soft-tissue visualization at 2 mGy dose to that of 10 mGy FBP image. Conclusion: The combination of rapid (5-10 minutes/scan) MC-based, patient-specific scatter correction and PL reconstruction offers an important means to overcome the current limitations of extremity CBCT in soft-tissue imaging.

  17. High-Performance Soft-Tissue Imaging in Extremity Cone-Beam CT

    PubMed Central

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Muhit, A.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2014-01-01

    Purpose Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. Methods The accelerated MC scatter correction involved fast MC simulation with low number of photons implemented on a GPU (107 photons/sec), followed by Gaussian kernel smoothing in the detector plane and across projection angles. PL reconstructions were investigated for reduction of imaging dose for projections acquired at ~2 mGy. Results The rapid scatter estimation yielded root-mean-squared-errors of scatter projections of ~15% of peak scatter intensity for 5·106 photons/projection (runtime ~0.5 sec/projection) and 25% improvement in fat-muscle contrast in reconstructions of a cadaveric knee. PL reconstruction largely restored soft-tissue visualization at 2 mGy dose to that of 10 mGy FBP image. Conclusion The combination of rapid (5–10 minutes/scan) MC-based, patient-specific scatter correction and PL reconstruction offers an important means to overcome the current limitations of extremity CBCT in soft-tissue imaging. PMID:25076825

  18. Laser diagnostic for high current H{sup {minus}} beams

    SciTech Connect

    Shafer, R.E.

    1998-01-01

    Laser photodetachment can be used on high current, high energy H{sup {minus}} beams to carry out a wide variety of beam diagnostic measurements parasitically during normal operation, without having to operate the facility at either reduced current or duty cycle. Suitable Q-switched laser systems are small, inexpensive, and can be mounted on or near the beamline. Most of the proposed laser-based diagnostics techniques have already been demonstrated.

  19. The evolution of extreme precipitations in high resolution scenarios over France

    NASA Astrophysics Data System (ADS)

    Colin, J.; Déqué, M.; Somot, S.

    2009-09-01

    Over the past years, improving the modelling of extreme events and their variability at climatic time scales has become one of the challenging issue raised in the regional climate research field. This study shows the results of a high resolution (12 km) scenario run over France with the limited area model (LAM) ALADIN-Climat, regarding the representation of extreme precipitations. The runs were conducted in the framework of the ANR-SCAMPEI national project on high resolution scenarios over French mountains. As a first step, we attempt to quantify one of the uncertainties implied by the use of LAM : the size of the area on which the model is run. In particular, we address the issue of whether a relatively small domain allows the model to create its small scale process. Indeed, high resolution scenarios cannot be run on large domains because of the computation time. Therefore one needs to answer this preliminary question before producing and analyzing such scenarios. To do so, we worked in the framework of a « big brother » experiment. We performed a 23-year long global simulation in present-day climate (1979-2001) with the ARPEGE-Climat GCM, at a resolution of approximately 50 km over Europe (stretched grid). This first simulation, named ARP50, constitutes the « big brother » reference of our experiment. It has been validated in comparison with the CRU climatology. Then we filtered the short waves (up to 200 km) from ARP50 in order to obtain the equivalent of coarse resolution lateral boundary conditions (LBC). We have carried out three ALADIN-Climat simulations at a 50 km resolution with these LBC, using different configurations of the model : * FRA50, run over a small domain (2000 x 2000 km, centered over France), * EUR50, run over a larger domain (5000 x 5000 km, centered over France as well), * EUR50-SN, run over the large domain (using spectral nudging). Considering the facts that ARPEGE-Climat and ALADIN-Climat models share the same physics and dynamics

  20. First high-precision differential abundance analysis of extremely metal-poor stars

    NASA Astrophysics Data System (ADS)

    Reggiani, Henrique; Meléndez, Jorge; Yong, David; Ramírez, Ivan; Asplund, Martin

    2016-02-01

    Context. Studies of extremely metal-poor stars indicate that chemical abundance ratios [X/Fe] have a root mean square scatter as low as 0.05 dex (12%). It remains unclear whether this reflects observational uncertainties or intrinsic astrophysical scatter arising from physical conditions in the interstellar medium at early times. Aims: We measure differential chemical abundance ratios in extremely metal-poor stars to investigate the limits of precision and to understand whether cosmic scatter or observational errors are dominant. Methods: We used high-resolution (R ~ 95 000) and high signal-to-noise (S/N = 700 at 5000 Å) HIRES/Keck spectra to determine high-precision differential abundances between two extremely metal-poor stars through a line-by-line differential approach. We determined stellar parameters for the star G64-37 with respect to the standard star G64-12. We performed EW measurements for the two stars for the lines recognized in both stars and performed spectral synthesis to study the carbon abundances. Results: The differential approach allowed us to obtain errors of σ(Teff) = 27 K, σ(log g) = 0.06 dex, σ( [Fe/H] ) = 0.02 dex and σ(vt) = 0.06 km s-1. We estimated relative chemical abundances with a precision as low as σ([X/Fe]) ≈ 0.01 dex. The small uncertainties demonstrate that there are genuine abundance differences larger than the measurement errors. The observed Li difference cannot be explained by the difference in mass because the less massive star has more Li. Conclusions: It is possible to achieve an abundance precision around ≈ 0.01-0.05 dex for extremely metal-poor stars, which opens new windows on the study of the early chemical evolution of the Galaxy. Table A.1 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A67

  1. New Pulsed Power Technology for High Current Accelerators

    SciTech Connect

    Caporaso, G J

    2002-06-27

    Recent advances in solid-state modulators now permit the design of a new class of high current accelerators. These new accelerators will be able to operate in burst mode at frequencies of several MHz with unprecedented flexibility and precision in pulse format. These new modulators can drive accelerators to high average powers that far exceed those of any other technology and can be used to enable precision beam manipulations. New insulator technology combined with novel pulse forming lines and switching may enable the construction of a new type of high gradient, high current accelerator. Recent developments in these areas will be reviewed.

  2. Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Ikpe, Stanley A.; Lauenstein, Jean-Marie; Carr, Gregory A.; Hunter, Don; Ludwig, Lawrence L.; Wood, William; Del Castillo, Linda Y.; Fitzpatrick, Fred; Chen, Yuan

    2016-01-01

    Silicon-Carbide device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon counterpart, Silicon-Carbide offers a greater possibility for high powered switching applications in extreme environment. In particular, Silicon-Carbide Metal-Oxide- Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing Silicon-Carbide power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.

  3. Motor monitoring method and apparatus using high frequency current components

    DOEpatents

    Casada, Donald A.

    1996-01-01

    A motor current analysis method and apparatus for monitoring electrical-motor-driven devices. The method and apparatus utilize high frequency portions of the motor current spectra to evaluate the condition of the electric motor and the device driven by the electric motor. The motor current signal produced as a result of an electric motor is monitored and the low frequency components of the signal are removed by a high-pass filter. The signal is then analyzed to determine the condition of the electrical motor and the driven device.

  4. Motor monitoring method and apparatus using high frequency current components

    DOEpatents

    Casada, D.A.

    1996-05-21

    A motor current analysis method and apparatus for monitoring electrical-motor-driven devices are disclosed. The method and apparatus utilize high frequency portions of the motor current spectra to evaluate the condition of the electric motor and the device driven by the electric motor. The motor current signal produced as a result of an electric motor is monitored and the low frequency components of the signal are removed by a high-pass filter. The signal is then analyzed to determine the condition of the electrical motor and the driven device. 16 figs.

  5. Scaling-up a liquid water jet laser plasma source to high average power for extreme-ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Vogt, Ulrich; Stiel, Holger; Will, Ingo; Wieland, Marek; Wilhein, Thomas; Nickles, Peter V.; Sandner, Wolfgang

    2001-08-01

    In this article we describe a laser plasma source for Extreme Ultraviolet Lithography (EUVL) based on a liquid water jet target. Although jet targets are known for some time now, no attempts have been made to prove the functionality of the target under conditions similar to an EUVL production-line facility, that means illumination with high average power laser systems (in the multi-kW regime) at repetition rates in the kHz region. Such systems are currently under development. We used the MBI-burst laser to simulate these extreme illumination conditions. We examined the hydrodynamic stability of the target as a function of the laser repetition rate at different average laser powers (0.6kW and 5kW per burst). Additionally, the dependence of the conversion efficiency on pulse duration in the range from 30ps to 3ns was investigated. From our results one can conclude parameters for future design of driver lasers for EUVL systems.

  6. A high-current calibration system based on indirect comparison of current transformer and Rogowski coil

    NASA Astrophysics Data System (ADS)

    Luo, Pandian; Li, Zhenhua; Li, Hongbin; Li, Hongfeng

    2013-12-01

    The calibration of the protective current transformer (CT) is of particular importance, since its accuracy at high currents is crucial to the correct operation of the subsequent relay protection devices. Conventional calibration methods have been using an electromagnetic CT which contains an iron core as the standard CT. The iron core is big and difficult to manufacture for high-current measurement, and the serious residual magnetism of the iron core at high currents can lead to excessive measurement errors. This paper proposes a calibration system based on indirect comparison of CT and Rogowski coil, i.e. using an iron-core CT to correct the error of the Rogowski coil at low currents, which may be caused by the position of the current-carrying conductor and so on, and then using the calibrated Rogowski coil as the standard transformer at high currents for its good linearity and wide dynamic range, and there is no magnetic saturation. Since the output of the Rogowski coil needs to be integrated, an improved digital integrator based on direct current (dc) negative feedback is adopted, which can effectively eliminate the influences of temperature drift, time drift and dc offset caused by the analogue circuit. The measurement errors of each part of the calibration system have also been discussed, and the test results show that the accuracy of the system can reach up to the 0.05S Class and the uncertainties are 0.038% for ratio and 0.68‧ for phase in the range 500 A to 50 kA.

  7. A Two-Dimensional Extremely Short Optical Pulse in a System of Carbon Nanotubes in a Direct Current Electric Field

    NASA Astrophysics Data System (ADS)

    Belonenko, M. B.; Galkina, E. N.; Filimonova, Z. A.

    2016-03-01

    The effect of an external dc electric field on the two-dimensional extremely short optical pulse propagating in a zigzag carbon nanotube array was investigated. The electromagnetic field evolution in the investigated nanotube system is described by the Maxwell equations. Using numerical simulation, the interaction between the pulse electromagnetic field and the external electric field applied to the carbon nanotube array is analyzed.

  8. Characterization of large format lithium ion battery exposed to extremely high temperature

    NASA Astrophysics Data System (ADS)

    Feng, Xuning; Sun, Jing; Ouyang, Minggao; He, Xiangming; Lu, Languang; Han, Xuebing; Fang, Mou; Peng, Huei

    2014-12-01

    This paper provides a study on the characterizations of large format lithium ion battery cells exposed to extreme high temperature but without thermal runaway. A unique test is set up: an extended volume-accelerating rate calorimetry (EV-ARC) test is terminated at a specific temperature before thermal runaway happens in the battery. The battery was cooled down after an EV-ARC test with early termination. The performances of the battery before and after the EV-ARC test are investigated in detail. The results show that (a) the melting point of the separator dictates the reusability of the 25 Ah NCM battery after a near-runaway event. The battery cannot be reused after being heated to 140 °C or higher because of the exponential rise in ohmic resistance; (b) a battery can lose up to 20% of its capacity after being heated to 120 °C just one time; (c) if a battery is cycled after a thermal event, its lost capacity may be recovered partially. Furthermore, the fading and recovery mechanisms are analyzed by incremental capacity analysis (ICA) and a prognostic/mechanistic model. Model analysis confirms that the capacity loss at extremely high temperature is caused by the increase of the resistance, the loss of lithium ion (LLI) at the anode and the loss of active material (LAM) at the cathode.

  9. Responsive Stabilization of Nanoparticles for Extreme Salinity and High-Temperature Reservoir Applications.

    PubMed

    Ranka, Mikhil; Brown, Paul; Hatton, T Alan

    2015-09-01

    Colloidal stabilization of nanoparticles under extreme salinity and high temperature conditions is a key challenge in the development of next generation technologies for subsurface reservoir characterization and oil recovery. Polyelectrolytes have been investigated as nanoparticle stabilizers, but typically fail at high ionic strengths and elevated temperatures due to excessive charge screening and dehydration. We report an approach to nanoparticle stabilization that overcomes these limitations, and exploits the antipolyelectrolyte phenomenon, in which screening of intrachain electrostatic interactions causes a polyzwitterion chain to undergo a structural transition from a collapsed globule to a more open coil-like regime with increases in ionic strength and temperature. Small-angle neutron scattering on a model zwitterionic polymer in solution indicated an increase in both radius of gyration and excluded volume parameter of the polymer with increases in ionic strength and temperature. The model zwitterion was subsequently incorporated within a polymeric stabilizer for nanoparticles under harsh reservoir conditions, and used to functionalize hydrophilic (silica) as well as hydrophobic (polystyrene) nanoparticles. Long-term colloidal stability was achieved at salt concentrations up to 120,000 mg/dm3 at 90 °C, approximately twice the stability limit previously reported in the literature. The approach can be broadly generalized to a large class of synthetic polyzwitterions, and can be adapted to a wide variety of other colloidal systems in which demands placed by extreme salinity and temperature conditions must be met. PMID:26278070

  10. Integrated compact optical current sensors with high sensitivity

    NASA Astrophysics Data System (ADS)

    Huang, Duanni; Pintus, Paolo; Srinivasan, Sudharsanan; Bowers, John E.

    2016-02-01

    We demonstrate a Sagnac based fiber optic current sensor using only 10cm of terbium doped fiber with a high Verdet constant of 15.5 rad/Tm at a wavelength of 1300nm. Measurements of the fiber inside a solenoid show over 40dB of open loop dynamic range as well as a minimum detectable current of 0.1mA. In order to decrease size while increasing sensitivity even further, we consider integrated magneto-optic waveguides as the sensing element. Using silicon waveguides alongside magneto-optic material such as cerium doped yttrium iron garnet (Ce:YiG), we model the Verdet constant to be as high as 10,000 rad/Tm. This improvement by three orders of magnitude shows potential for magnetooptic waveguides to be used in ultra-high sensitivity optical magnetometers and current sensors. Finally, we propose a fully integrated optical current sensor using heterogeneous integration for silicon photonics.