Science.gov

Sample records for large area negative

  1. Large-Area Flexible 3D Optical Negative Index Metamaterial Formed by Nanotransfer Printing

    DTIC Science & Technology

    2011-07-01

    metamaterial formed by nanotransfer printing Debashis Chanda1, Kazuki Shigeta1, Sidhartha Gupta1, Tyler Cain1, Andrew Carlson1, Agustin Mihi1, Alfred J. Baca3...2008). 11. Dolling, G., Enkrich, C. & Wegener , M. Low-loss negative-index metamaterial at telecommunication wavelengths. Opt. Lett. 31, 1800–1802 (2006...metamaterials. Phys. Rev. B 75, 024304 (2007). 13. Dolling, G., Wegener , M. & Linden, S. Realization of a three-functional-layer negative-index photonic

  2. Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

    NASA Astrophysics Data System (ADS)

    Doo-Hee, Chang; Seung, Ho Jeong; Min, Park; Tae-Seong, Kim; Bong-Ki, Jung; Kwang, Won Lee; Sang Ryul, In

    2016-12-01

    A large-area high-power radio-frequency (RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute (KAERI). The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argon-gas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter, such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the short-and long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region. supported by the Ministry of Science, ICT and Future Planning of the Republic of Korea under the ITER Technology R&D Program, and National R&D Program Through the National Research Foundation of Korea (NRF) Funded by the Ministry of Science, ICT & Future Planning (NRF-2014M1A7A1A03045372)

  3. Large area LED package

    NASA Astrophysics Data System (ADS)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  4. Large area mass analyzer

    NASA Astrophysics Data System (ADS)

    Rachev, Mikhail; Srama, Ralf; Srowig, Andre; Grün, Eberhard

    2004-12-01

    A new time-of-flight spectrometer for the chemical analysis of cosmic dust particles in space has been simulated by Simion 7.0. The instrument is based upon impact ionization. This method is a reliable method for in situ dust detection and is well established. Instruments using the impact ionization flew on board of Helios and Galileo and are still in operation on board of the Ulysses and Cassini-Huygens missions. The new instrument has a large sensitive area of 0.1 m2 in order to achieve a significant number of measurements. The mass resolution M/ΔM>100 and the mass range covers the most relevant elements expected in cosmic dust. The instrument has a reflectron configuration which increases the mass resolution. Most of the ions released during the impact are focused to the detector. The ion detector consists of a large area ion-to-electron converter, an electron reflectron and a microchannel plate detector.

  5. The Large Area Telescope

    SciTech Connect

    Michelson, Peter F.; /KIPAC, Menlo Park /Stanford U., HEPL

    2007-11-13

    The Large Area Telescope (LAT), one of two instruments on the Gamma-ray Large Area Space Telescope (GLAST) mission, is an imaging, wide field-of-view, high-energy pair-conversion telescope, covering the energy range from {approx}20 MeV to more than 300 GeV. The LAT is being built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. The scientific objectives the LAT will address include resolving the high-energy gamma-ray sky and determining the nature of the unidentified gamma-ray sources and the origin of the apparently isotropic diffuse emission observed by EGRET; understanding the mechanisms of particle acceleration in celestial sources, including active galactic nuclei, pulsars, and supernovae remnants; studying the high-energy behavior of gamma-ray bursts and transients; using high-energy gamma-rays to probe the early universe to z {ge} 6; and probing the nature of dark matter. The components of the LAT include a precision silicon-strip detector tracker and a CsI(Tl) calorimeter, a segmented anticoincidence shield that covers the tracker array, and a programmable trigger and data acquisition system. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large field-of-view and ensuring that nearly all pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. This paper includes a description of each of these LAT subsystems as well as a summary of the overall performance of the telescope.

  6. Large area Czochralski silicon

    NASA Technical Reports Server (NTRS)

    Rea, S. N.; Gleim, P. S.

    1977-01-01

    The overall cost effectiveness of the Czochralski process for producing large-area silicon was determined. The feasibility of growing several 12 cm diameter crystals sequentially at 12 cm/h during a furnace run and the subsequent slicing of the ingot using a multiblade slurry saw were investigated. The goal of the wafering process was a slice thickness of 0.25 mm with minimal kerf. A slice + kerf of 0.56 mm was achieved on 12 cm crystal using both 400 grit B4C and SiC abrasive slurries. Crystal growth experiments were performed at 12 cm diameter in a commercially available puller with both 10 and 12 kg melts. Several modifications to the puller hoz zone were required to achieve stable crystal growth over the entire crystal length and to prevent crystallinity loss a few centimeters down the crystal. The maximum practical growth rate for 12 cm crystal in this puller design was 10 cm/h, with 12 to 14 cm/h being the absolute maximum range at which melt freeze occurred.

  7. Large area bulk superconductors

    DOEpatents

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  8. Large area plasma source

    NASA Technical Reports Server (NTRS)

    Foster, John (Inventor); Patterson, Michael (Inventor)

    2008-01-01

    An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

  9. Beamlet deflection due to beamlet-beamlet interaction in a large-area multiaperture negative ion source for JT-60U

    SciTech Connect

    Kamada, M.; Hanada, M.; Ikeda, Y.; Grisham, L. R.; Jiang, W.

    2008-02-15

    The JT-60U negative ion source has been designed to produce high current beams of 22 A through grids of 1080 apertures (five segments with nine rows of 24 apertures). One of the key issues is to steer such a high current beam through the multiaperture grids in order to focus the overall beam envelope because the beamlet-beamlet interaction may deflect the outer beamlets outward due to unbalanced space charge repulsion. To clarify the beam deflection in the JT-60U negative ion source, the beamlet trajectory in a multiaperture ion source was calculated by a three-dimensional simulation code. The measured angles of the outmost beamlets were in agreement with the calculated results where space charge of the beamlets was taken into account. It is noticed that the deflection of the outermost beamlet due to the beamlet-beamlet interaction is saturated at 5.2 mrad outward for beamlets more than ten.

  10. Fermi's Large Area Telescope (LAT)

    NASA Video Gallery

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  11. Large area mercuric iodide photodetectors

    SciTech Connect

    Iwanczyk, J.S.; Dabrowski, A.J.; Markakis, J.M.; Ortale, C.; Schnepple, W.F.

    1984-02-01

    Results of an investigation of large area mercuric iodide (HgI/sub 2/) photodetectors are reported. Different entrance contacts were studied, including semitransparent metallic films and conductive liquids. Theoretical calculations of electronic noise of these photodetectors were compared with experimental results. HgI/sub 2/ photodetectors with active area up to 4 cm/sup 2/ were matched with NaI(Tl) and CsI(Tl) scintillation crystals and were evaluated as gamma-radiation spectrometers. Energy resolution of 9.3% for gamma radiation of 511 keV with a CsI(Tl) scintillator and energy resolution of 9.0% for gamma radiation of 622 keV with a NaI(Tl) scintillator have been obtained.

  12. Reducing the Negative Effects of Large Schools.

    ERIC Educational Resources Information Center

    Duke, Daniel L.; Trautvetter, Sara

    This report presents an overview of recent efforts to promote small schools by first reviewing the rationale for small schools based on recent studies linking school size and various educational outcomes, followed by arguments supporting larger schools. Succeeding sections explore the following four ways to reduce the negative effects of school…

  13. Large area pulsed solar simulator

    NASA Technical Reports Server (NTRS)

    Kruer, Mark A. (Inventor)

    1999-01-01

    An advanced solar simulator illuminates the surface a very large solar array, such as one twenty feet by twenty feet in area, from a distance of about twenty-six feet with an essentially uniform intensity field of pulsed light of an intensity of one AMO, enabling the solar array to be efficiently tested with light that emulates the sun. Light modifiers sculpt a portion of the light generated by an electrically powered high power Xenon lamp and together with direct light from the lamp provide uniform intensity illumination throughout the solar array, compensating for the square law and cosine law reduction in direct light intensity, particularly at the corner locations of the array. At any location within the array the sum of the direct light and reflected light is essentially constant.

  14. Large area perovskite solar cell module

    NASA Astrophysics Data System (ADS)

    Cai, Longhua; Liang, Lusheng; Wu, Jifeng; Ding, Bin; Gao, Lili; Fan, Bin

    2017-01-01

    The recent dramatic rise in power conversion efficiencies (PCE) of perovskite solar cells has triggered intense research worldwide. However, their practical development is hampered by poor stability and low PCE values with large areas devices. Here, we developed a gas-pumping method to avoid pinholes and eliminate local structural defects over large areas of perovskite film, even for 5 × 5 cm2 modules, the PCE reached 10.6% and no significant degradation was found after 140 days of outdoor testing. Our approach enables the realization of high performance large-area PSCs for practical application.

  15. Reducing the Negative Effects of Large Schools. Revised

    ERIC Educational Resources Information Center

    Duke, Daniel L.; DeRoberto, Thomas; Trautvetter, Sarah

    2009-01-01

    This document reviews recent efforts to promote small schools. The rationale for small schools is discussed, drawing on recent studies linking school size and various outcomes. Arguments for large schools are considered, followed by an examination of four ways to reduce the negative effects of school size--build smaller schools, utilize satellite…

  16. Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors

    SciTech Connect

    Yoshida, M. Hanada, M.; Kojima, A.; Kashiwagi, M.; Umeda, N.; Hiratsuka, J.; Ichikawa, M.; Watanabe, K.; Grisham, L.R.; Tsumori, K.; Kisaki, M.

    2016-02-15

    To understand the physics of the cesium (Cs) recycling in the large Cs-seeded negative ion sources relevant to ITER and JT-60SA with ion extraction area of 45-60 cm × 110-120 cm, the time evolution of the negative ion profile was precisely measured in JT-60SA where the ion extraction area is longitudinally segmented into 5. The Cs was seeded from the oven at 180 °C to the ion source. After 1 g of Cs input, surface production of the negative ions appeared only in the central segment where a Cs nozzle was located. Up to 2 g of Cs, the negative ion profile was longitudinally expanded over full ion extraction area. The measured time evolution of the negative ion profile has the similar tendency of distribution of the Cs atoms that is calculated. From the results, it is suggested that Cs atom distribution is correlated with the formation of the negative ion profile.

  17. Large negative Goos Hanchen shift at metal surfaces

    NASA Astrophysics Data System (ADS)

    Leung, P. T.; Chen, C. W.; Chiang, H.-P.

    2007-08-01

    It has been previously established that for p-polarized light incident onto a semi-infinite absorbing medium, large negative Goos-Hanchen (GH) shifts can be expected in the case of weak absorption at incidence close to the Brewster angle. The effect has been demonstrated for certain semiconducting media at optical frequencies. Here we point out that similar phenomenon can take place for strongly reflecting and attenuating medium such as metal at IR frequencies, with large incident angles close to grazing incidence. Moreover, unlike the previously-studied case with semiconductors, the Brewster angle in the present case with metals plays an insignificant role in the possible hindrance of the observation of such large negative shifts.

  18. Large area monolithic organic solar cells

    NASA Astrophysics Data System (ADS)

    Jin, Hui; Tao, Cheng; Hambsch, Mike; Pivrikas, Almantas; Velusamy, Marappan; Aljada, Muhsen; Zhang, Yuliang; Burn, Paul L.; Meredith, Paul

    2012-11-01

    Although efficiencies of > 10% have recently been achieved in laboratory-scale organic solar cells, these competitive performance figures are yet to be translated to large active areas and geometries relevant for viable manufacturing. One of the factors hindering scale-up is a lack of knowledge of device physics at the sub-module level, particularly cell architecture, electrode geometry and current collection pathways. A more in depth understanding of how photocurrent and photovoltage extraction can be optimised over large active areas is urgently needed. Another key factor suppressing conversion efficiencies in large area cells is the relatively high sheet resistance of the transparent conducting anode - typically indium tin oxide. Hence, to replace ITO with alternative transparent conducting anodes is also a high priority on the pathway to viable module-level organic solar cells. In our paper we will focus on large area devices relevant to sub-module scales - 5 cm × 5 cm monolithic geometry. We have applied a range of experimental techniques to create a more comprehensive understanding of the true device physics that could help make large area, monolithic organic solar cells more viable. By employing this knowledge, a novel transparent anode consisting of molybdenum oxide (MoOx) and silver (Ag) is developed to replace ITO and PEDOT-free large area solar cell sub-modules, acting as both a transparent window and hole-collecting electrode. The proposed architecture and anode materials are well suited to high throughput, low cost all-solution processing.

  19. Increased tornado hazard in large metropolitan areas

    NASA Astrophysics Data System (ADS)

    Cusack, Stephen

    2014-11-01

    The tornado climate was compared between large metropolitan areas and neighbouring non-metro cities using modern tornado reports in the Storm Prediction Center (SPC) archives. Twenty large metro areas in the higher-risk region of the U.S. were used to boost sample sizes hence robustness of results. Observational biases were minimised by using the most densely populated zips. The analysis found 50% greater tornado frequency and a thicker-tailed severity distribution in metro areas compared to the non-metro cities. These differences are significant at the 1% level. Regarding tornado frequency, the primary question is whether the raised occurrence rates in metro areas are due to observation biases or real differences in tornado climate. Past studies found no relative biases at the population densities used here, whereas there are two potential urban drivers of tornadogenesis. First, the urban heat island raises the storm severity above and downwind of main urban areas, as recorded in precipitation and lightning datasets. Second, the increased surface roughness over metro areas raises low-level shear which in turn has been found to be favourable for tornadogenesis. Modification of convective storms over large metro areas is the more plausible explanation of raised tornado frequency. The drivers of a thicker-tailed tornado severity distribution in metro areas are less certain. Potential causes include: increased debris-loading in metro tornadoes; modification of storms' lower boundary layer by increased surface roughness in metro areas; the reduced density of damage indicators in non-metro cities.

  20. Large area damage testing of optics

    SciTech Connect

    Sheehan, L.; Kozlowski, M.; Stolz, C.

    1996-04-26

    The damage threshold specifications for the National Ignition Facility will include a mixture of standard small-area tests and new large-area tests. During our studies of laser damage and conditioning processes of various materials we have found that some damage morphologies are fairly small and this damage does not grow with further illumination. This type of damage might not be detrimental to the laser performance. We should therefore assume that some damage can be allowed on the optics, but decide on a maximum damage allowance of damage. A new specification of damage threshold termed {open_quotes}functional damage threshold{close_quotes} was derived. Further correlation of damage size and type to system performance must be determined in order to use this measurement, but it is clear that it will be a large factor in the optics performance specifications. Large-area tests have verified that small-area testing is not always sufficient when the optic in question has defect-initiated damage. This was evident for example on sputtered polarizer and mirror coatings where the defect density was low enough that the features could be missed by standard small- area testing. For some materials, the scale-length at which damage non-uniformities occur will effect the comparison of small-area and large-area tests. An example of this was the sub-aperture tests on KD*P crystals on the Beamlet test station. The tests verified the large-area damage threshold to be similar to that found when testing a small-area. Implying that for this KD*P material, the dominate damage mechanism is of sufficiently small scale-length that small-area testing is capable of determining the threshold. The Beamlet test station experiments also demonstrated the use of on-line laser conditioning to increase the crystals damage threshold.

  1. H3O(+) tetrahedron induction in large negative linear compressibility.

    PubMed

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan

    2016-05-17

    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O(+) tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials.

  2. H3O+ tetrahedron induction in large negative linear compressibility

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan

    2016-05-01

    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)•2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O+ tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials.

  3. Large Area Synthesis of 2D Materials

    NASA Astrophysics Data System (ADS)

    Vogel, Eric

    Transition metal dichalcogenides (TMDs) have generated significant interest for numerous applications including sensors, flexible electronics, heterostructures and optoelectronics due to their interesting, thickness-dependent properties. Despite recent progress, the synthesis of high-quality and highly uniform TMDs on a large scale is still a challenge. In this talk, synthesis routes for WSe2 and MoS2 that achieve monolayer thickness uniformity across large area substrates with electrical properties equivalent to geological crystals will be described. Controlled doping of 2D semiconductors is also critically required. However, methods established for conventional semiconductors, such as ion implantation, are not easily applicable to 2D materials because of their atomically thin structure. Redox-active molecular dopants will be demonstrated which provide large changes in carrier density and workfunction through the choice of dopant, treatment time, and the solution concentration. Finally, several applications of these large-area, uniform 2D materials will be described including heterostructures, biosensors and strain sensors.

  4. Method of Making Large Area Nanostructures

    NASA Technical Reports Server (NTRS)

    Marks, Alvin M.

    1995-01-01

    A method which enables the high speed formation of nanostructures on large area surfaces is described. The method uses a super sub-micron beam writer (Supersebter). The Supersebter uses a large area multi-electrode (Spindt type emitter source) to produce multiple electron beams simultaneously scanned to form a pattern on a surface in an electron beam writer. A 100,000 x 100,000 array of electron point sources, demagnified in a long electron beam writer to simultaneously produce 10 billion nano-patterns on a 1 meter squared surface by multi-electron beam impact on a 1 cm squared surface of an insulating material is proposed.

  5. Double negative pressure for seroma treatment in trocanteric area.

    PubMed

    Calderon, Wilfredo L; Llanos, Sergio; Leniz, Patricio; Danilla, Stefan; Vielma, Rodrigo; Calderon, Daniel

    2009-12-01

    We report the use of topic negative pressure for seromas resulting from mobilization of tensor fascia lata miocutaneous flap in the trochanteric areas for pressure sores. In 5 consecutive patients we successfully treated seroma with the use of external and internal topic subatmospheric pressure.

  6. Stowable large area solar power module

    SciTech Connect

    Hanak, J.J.

    1987-12-15

    A stowable, deployable large area solar module is described comprising: discrete, interconnected, flexible, large area solar panels; hinge means operatively disposed on the panels so as to provide for the relative planar displacement of the folded panels of the module when the panels are folded in overlying sandwiched relationship; the hinge means also operatively disposed so as to provide for the folded panels to be rolled into a stowable, substantially cylindrical configuration. The hinge means comprise: hinge knuckles associated with at least one edge of each large area panel, each of the knuckles including a passage therethrough adapted to receive pintle means, the knuckles of adjacent panels disposed in a spaced apart, generally coplanar, interdigitating relationship; and, flexible pintle means disposed so as to sequentially pass through the interdigitating knuckles, whereby the spaced apart knuckles allow for a degree of planar displacement of adjoining large area panels relative to one another, as well as allowing for the folding of the panels in a sandwiched relationship and the flexible pintle means allows for the panels to be rolled into the substantially cylindrical configuration.

  7. Large area space solar cell assemblies

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Nowlan, M. J.

    1982-01-01

    Development of a large area space solar cell assembly is presented. The assembly consists of an ion implanted silicon cell and glass cover. The important attributes of fabrication are (1) use of a back surface field which is compatible with a back surface reflector, and (2) integration of coverglass application and call fabrication.

  8. Predicting Positive and Negative Relationships in Large Social Networks.

    PubMed

    Wang, Guan-Nan; Gao, Hui; Chen, Lian; Mensah, Dennis N A; Fu, Yan

    2015-01-01

    In a social network, users hold and express positive and negative attitudes (e.g. support/opposition) towards other users. Those attitudes exhibit some kind of binary relationships among the users, which play an important role in social network analysis. However, some of those binary relationships are likely to be latent as the scale of social network increases. The essence of predicting latent binary relationships have recently began to draw researchers' attention. In this paper, we propose a machine learning algorithm for predicting positive and negative relationships in social networks inspired by structural balance theory and social status theory. More specifically, we show that when two users in the network have fewer common neighbors, the prediction accuracy of the relationship between them deteriorates. Accordingly, in the training phase, we propose a segment-based training framework to divide the training data into two subsets according to the number of common neighbors between users, and build a prediction model for each subset based on support vector machine (SVM). Moreover, to deal with large-scale social network data, we employ a sampling strategy that selects small amount of training data while maintaining high accuracy of prediction. We compare our algorithm with traditional algorithms and adaptive boosting of them. Experimental results of typical data sets show that our algorithm can deal with large social networks and consistently outperforms other methods.

  9. Predicting Positive and Negative Relationships in Large Social Networks

    PubMed Central

    Wang, Guan-Nan; Gao, Hui; Chen, Lian; Mensah, Dennis N. A.; Fu, Yan

    2015-01-01

    In a social network, users hold and express positive and negative attitudes (e.g. support/opposition) towards other users. Those attitudes exhibit some kind of binary relationships among the users, which play an important role in social network analysis. However, some of those binary relationships are likely to be latent as the scale of social network increases. The essence of predicting latent binary relationships have recently began to draw researchers' attention. In this paper, we propose a machine learning algorithm for predicting positive and negative relationships in social networks inspired by structural balance theory and social status theory. More specifically, we show that when two users in the network have fewer common neighbors, the prediction accuracy of the relationship between them deteriorates. Accordingly, in the training phase, we propose a segment-based training framework to divide the training data into two subsets according to the number of common neighbors between users, and build a prediction model for each subset based on support vector machine (SVM). Moreover, to deal with large-scale social network data, we employ a sampling strategy that selects small amount of training data while maintaining high accuracy of prediction. We compare our algorithm with traditional algorithms and adaptive boosting of them. Experimental results of typical data sets show that our algorithm can deal with large social networks and consistently outperforms other methods. PMID:26075404

  10. GLAST Large Area Telescope Multiwavelength Planning

    SciTech Connect

    Reimer, O.; Michelson, P.F.; Cameron, R.A.; Digel, S.W.; Thompson, D.J.; Wood, K.S.

    2007-01-03

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  11. GLAST Large Area Telescope Multiwavelength Planning

    NASA Technical Reports Server (NTRS)

    Reimer, O.; Michelson, P. F.; Cameron, R. A.; Digel, S. W.; Thompson, D. J.; Wood, K. S.

    2007-01-01

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  12. Large-area thin-film modules

    NASA Astrophysics Data System (ADS)

    Tyan, Y. S.; Perez-Albuerne, E. A.

    1985-10-01

    The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

  13. MeerKAT Large Area Survey

    NASA Astrophysics Data System (ADS)

    Leeuw, Lerothodi

    2017-01-01

    We present the goals and strategies for a large area MeerKAT survey, that is expected to be proposed under the MeerKAT open time call. The survey will be at least 400 square degrees, detect galaxies up to high redshift and cover various science interests that will exploit synergies with complementary data at other wavebands. For as high impact and legacy value as possible, the survey is open to synergies from the community.

  14. Large-area thin-film modules

    NASA Technical Reports Server (NTRS)

    Tyan, Y. S.; Perez-Albuerne, E. A.

    1985-01-01

    The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

  15. Large-Area Vacuum Ultraviolet Sensors

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Franz, David

    2012-01-01

    Pt/(n-doped GaN) Schottky-barrier diodes having active areas as large as 1 cm square have been designed and fabricated as prototypes of photodetectors for the vacuum ultraviolet portion (wavelengths approximately equal 200 nm) of the solar spectrum. In addition to having adequate sensitivity to photons in this wavelength range, these photodetectors are required to be insensitive to visible and infrared components of sunlight and to have relatively low levels of dark current.

  16. Laser crystallization for large-area electronics

    NASA Astrophysics Data System (ADS)

    Sameshima, Toshiyuki

    2009-07-01

    Laser crystallization is reviewed for the purpose of fabrication of polycrystalline silicon thin film transistors (poly-Si TFTs). Laser-induced rapid heating is important for formation of crystalline films with a low thermal budget. Reduction of electrically active defects located at grain boundaries is essential for improving electrical properties of poly-Si films and achieving poly-Si TFTs with high performances. The internal film stress is attractive to increase the carrier mobility. Recent developments in laser crystallization methods with pulsed and continuous-wave lasers are also reviewed. Control of heat flow results in crystalline grain growth in the lateral direction, which is important for fabrication of large crystalline grains. We also report an annealing method using a high-power infrared semiconductor laser. High-power lasers will be attractive for rapid formation of crystalline films over a large area and activation of silicon with impurity atoms.

  17. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  18. Supernova Remnants with Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Caragiulo, M.; Di Venere, L.

    2017-03-01

    The Large Area Telescope (LAT), on-board the Fermi satellite, proved to be, after 8 years of data taking, an excellent instrument to detect and observe Supernova Remnants (SNRs) in a range of energies running from few hundred MeV up to few hundred GeV. It provides essential information on physical processes that occur at the source, involving both accelerated leptons and hadrons, in order to understand the mechanisms responsible for the primary Cosmic Ray (CR) acceleration. We show the latest results in the observation of Galactic SNRs by Fermi-LAT.

  19. Large Area X-Ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.

    1997-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

  20. High Efficiency Large Area Polysilicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Johnson, S. M.; Winter, C.

    1985-01-01

    Large area (100 sq cm) polysilicon solar cells having efficiencies of up to 14.1% (100 mW/sq cm, 25 C) were fabricated and a detailed analysis was performed to identify the efficiency loss mechanisms. The 1-5 characteristics of the best cell were dominated by recombination in the quasi-neutral base due to the combination of minority carrier diffusion length and base resistivity. An analysis of the microstructural defects present in the material and their effect on the electrical properties is presented.

  1. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1994-01-01

    The Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, CA, occupies an area measuring about 3 m wide x 12 m long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than plus or minus 2 percent uniformity of irradiance at the test plane and better than plus or minus 0.3 percent measurement repeatability after warm-up. Glass absorption filters reduce the ultraviolet light emitted from the xenon flash lamps. This results in a close match to three different standard airmass zero and airmass 1.5 spectral irradiances. The 2-ms light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices. Since the original printing of this publication, in 1993, the LAPSS has been operational and new capabilities have been added. This revision includes a new section relating to the installation of a method to measure the I-V curve of a solar cell or array exhibiting a large effective capacitance. Another new section has been added relating to new capabilities for plotting single and multiple I-V curves, and for archiving the I-V data and test parameters. Finally, a section has been added regarding the data acquisition electronics calibration.

  2. Large Area Lunar Dust Flux Measurement Instrument

    NASA Technical Reports Server (NTRS)

    Corsaro, R.; Giovane, F.; Liou, Jer-Chyi; Burchell, M.; Stansbery, Eugene; Lagakos, N.

    2009-01-01

    The instrument under development is designed to characterize the flux and size distribution of the lunar micrometeoroid and secondary ejecta environment. When deployed on the lunar surface, the data collected will benefit fundamental lunar science as well as enabling more reliable impact risk assessments for human lunar exploration activities. To perform this task, the instrument requirements are demanding. It must have as large a surface area as possible to sample the very sparse population of the larger potentially damage-inducing micrometeorites. It must also have very high sensitivity to enable it to measure the flux of small (<10 micron) micrometeorite and secondary ejecta dust particles. To be delivered to the lunar surface, it must also be very low mass, rugged and stow compactly. The instrument designed to meet these requirements is called FOMIS. It is a large-area thin film under tension (i.e. a drum) with multiple fiber optic displacement (FOD) sensors to monitor displacements of the film. This sensor was chosen since it can measure displacements over a wide dynamic range: 1 cm to sub-Angstrom. A prototype system was successfully demonstrated using the hypervelocity impact test facility at the University of Kent (Canterbury, UK). Based on these results, the prototype system can detect hypervelocity (approx.5 km/s) impacts by particles as small as 2 microns diameter. Additional tests using slow speeds find that it can detect secondary ejecta particles (which do not penetrate the film) with momentums as small as 15 pico-gram 100m/s, or nominally 5 microns diameter at 100 m/s.

  3. Large-area mapping of biodiversity

    USGS Publications Warehouse

    Scott, J.M.; Jennings, M.D.

    1998-01-01

    The age of discovery, description, and classification of biodiversity is entering a new phase. In responding to the conservation imperative, we can now supplement the essential work of systematics with spatially explicit information on species and assemblages of species. This is possible because of recent conceptual, technical, and organizational progress in generating synoptic views of the earth's surface and a great deal of its biological content, at multiple scales of thematic as well as geographic resolution. The development of extensive spatial data on species distributions and vegetation types provides us with a framework for: (a) assessing what we know and where we know it at meso-scales, and (b) stratifying the biological universe so that higher-resolution surveys can be more efficiently implemented, coveting, for example, geographic adequacy of specimen collections, population abundance, reproductive success, and genetic dynamics. The land areas involved are very large, and the questions, such as resolution, scale, classification, and accuracy, are complex. In this paper, we provide examples from the United States Gap Analysis Program on the advantages and limitations of mapping the occurrence of terrestrial vertebrate species and dominant land-cover types over large areas as joint ventures and in multi-organizational partnerships, and how these cooperative efforts can be designed to implement results from data development and analyses as on-the-ground actions. Clearly, new frameworks for thinking about biogeographic information as well as organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The Gap Analysis experience provides one model for achieving these new frameworks.

  4. Development of large Area Covering Height Model

    NASA Astrophysics Data System (ADS)

    Jacobsen, K.

    2014-04-01

    Height information is a basic part of topographic mapping. Only in special areas frequent update of height models is required, usually the update cycle is quite lower as for horizontal map information. Some height models are available free of charge in the internet; for commercial height models a fee has to be paid. Mostly digital surface models (DSM) with the height of the visible surface are given and not the bare ground height, as required for standard mapping. Nevertheless by filtering of DSM, digital terrain models (DTM) with the height of the bare ground can be generated with the exception of dense forest areas where no height of the bare ground is available. These height models may be better as the DTM of some survey administrations. In addition several DTM from national survey administrations are classified, so as alternative the commercial or free of charge available information from internet can be used. The widely used SRTM DSM is available also as ACE-2 GDEM corrected by altimeter data for systematic height errors caused by vegetation and orientation errors. But the ACE-2 GDEM did not respect neighbourhood information. With the worldwide covering TanDEM-X height model, distributed starting 2014 by Airbus Defence and Space (former ASTRIUM) as WorldDEM, higher level of details and accuracy is reached as with other large area covering height models. At first the raw-version of WorldDEM will be available, followed by an edited version and finally as WorldDEM-DTM a height model of the bare ground. With 12 m spacing and a relative standard deviation of 1.2 m within an area of 1° x 1° an accuracy and resolution level is reached, satisfying also for larger map scales. For limited areas with the HDEM also a height model with 6 m spacing and a relative vertical accuracy of 0.5 m can be generated on demand. By bathymetric LiDAR and stereo images also the height of the sea floor can be determined if the water has satisfying transparency. Another method of getting

  5. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    Kalejs, J. P.

    1982-01-01

    Work carried out on the JPL Flat Plate Solar Array Project, for the purpose of developing a method for silicon ribbon production by Edge-defined Film-fed Growth (EEG) for use as low-cost substrate material in terrestrial solar cell manufacture, is described. A multiple ribbon furnace unit that is designed to operate on a continuous basis for periods of at least one week, with melt replenishment and automatic ribbon width control, and to produce silicon sheet at a rate of one square meter per hour, was constructed. Program milestones set for single ribbon furnace operation to demonstrate basic EEG system capabilities with respect to growth speed, thickness and cell performance were achieved for 10 cm wide ribbon: steady-state growth at 4 cm/min and 200 micron thickness over periods of an hour and longer was made routine, and a small area cell efficiency of 13+% demonstrated. Large area cells of average efficiency of 10 to 11%, with peak values of 11 to 12% were also achieved. The integration of these individual performance levels into multiple ribbon furnace operation was not accomplished.

  6. Negative-pressure solar dryer for large round alfalfa bales

    SciTech Connect

    Frisby, J.C.; George, R.M.; Everett, J.T.

    1985-01-01

    A single-bale, portable, negative-pressure solar dryer was constructed and tested. It was found that design criteria established on pressurized systems could be used for negative-pressure systems. Hay packaged at 40 percent moisture content dried more uniformly if baled with a fixed-chamber baler.

  7. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  8. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Progress was made in improving ribbon flatness and reducing stress, and in raising cell performance for 10 cm wide ribbon grown in single cartridge EFG furnaces. Optimization of growth conditions resulted in improved ribbon thickness uniformity at a thickness of 200 micron, grown at 4 cm/minute, and growth at this target speed is routinely achieved over periods of the order of one hour or more. With the improved ribbon flatness, fabrication of large area (50 cm2) cells is now possible, and 10 to 11% efficiencies were demonstrated on ribbon grown at 3.5 to 4 cm/minute. Factors limiting performance of the existing multiple ribbon furnace were identified, and growth system improvements implemented to help raise throughput rates and the time percentage of simultaneous three-ribbon growth. However, it is evident that major redesign of this furnace would be needed to overcome shortfalls in its ability to achieve the Technical Features Demonstration goals of 1980. It was decided to start construction of a new multiple ribbon furnace and to incorporate the desired improvements into its design. The construction of this furnace is completed.

  9. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    SciTech Connect

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Abdo, A. A.; Ackermann, M.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Belfiore, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Bignami, G. F. E-mail: Gino.Tosti@pg.infn.it E-mail: tburnett@u.washington.edu; and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  10. Fermi Large Area Telescope Second Source Catalog

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.; Davis, D. S.; DeCesar, M. E.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; Johnson, T. E.; McConville, W.; McEnery, J. E; Perkins, J. S.; Racusin, J. L; Scargle, J. D.; Stephens, T. E.; Thompson, D. J.; Troja, E.

    2012-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 11eV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely gamma-ray-producing source classes.

  11. Positively and negatively large Goos-Hänchen lateral displacements from a single negative layered structure.

    PubMed

    Talebzadeh, Robabeh; Namdar, Abdolrahman

    2012-09-20

    We study the electromagnetic beam reflection from layered structures that include the so-called ε-negative and the μ-negative materials, also called single negative materials. We predict that such structures can demonstrate a giant lateral Goos-Hänchen shift of the resonant excitation of surface waves at the interface between the conventional and single negative materials, as well as due to the excitation of leaky modes in the layered structures. Then we replace the conventional layer with a left-handed layer (a material with both ε<0 and μ<0). We show that the Goos-Hänchen shift can be positive and negative depending on the type of this layer (conventional or LH material), which can support TE or TM surface waves.

  12. Large Area X-ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, Harvey

    1996-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission study concept has evolved strongly over the last year culminating in the merging of LAXS with the Goddard Space Flight Center (GSFC) proposal for a similar mission, the Next Generation X-ray Observatory (NGXO, PI: Nick White). The resulting merger, re-named the High Throughput X-rays Spectroscopy (HTXS) Mission has also expanded by the inclusion of another SAO proposed new mission concept proposal, the Hard X-Ray Telescope (PI: Paul Gorenstein). The resultant multi-instrument mission retains much of heritage from the LAXS proposal, including the use of multiple satellites for robustness. These mergers resulted from a series of contacts between various team members, via e-mail, telecons, and in-person meetings. The impetus for the mergers was the fundamental similarity between the missions, and the recognition that all three proposal teams had significant contributions to make in the effort to define the next stage in the X-ray exploration of the universe. We have enclosed four items that represent some of the work that has occurred during the first year of the study: first, a presentation at the Leicester meeting, second a presentation that was made to Dan Goldin following the merging of LAXS and NGXO, third a copy of the first announcement for the Workshop, and finally the interim report that was prepared by the HTXS study team towards the end of the first year. This last document provides the foundation for the HTXS Technology Roadmap that is being generated. The HTXS roadmap will define the near-term goals that the merged mission must achieve over the next few years. A web site has been developed and populated that contains much of the material that has been generated over the past year.

  13. Fermi Large Area Telescope First Source Catalog

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Belli, F.; Berenji, B.; Bisello, D.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Canadas, B.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Cillis, A. N.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Corbet, R.; Davis, D. S.; DeKlotz, M.; den Hartog, P. R.; Dermer, C. D.; de Angelis, A.; de Luca, A.; de Palma, F.; Digel, S. W.; Dormody, M.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Fabiani, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giavitto, G.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Marangelli, B.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paccagnella, A.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pinchera, M.; Piron, F.; Porter, T. A.; Poupard, L.; Rainò, S.; Rando, R.; Ray, P. S.; Razzano, M.; Razzaque, S.; Rea, N.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Scolieri, G.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stephens, T. E.; Striani, E.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Van Etten, A.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Watters, K.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.; Fermi LAT Collaboration

    2010-06-01

    We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.

  14. Polyurethane Masks Large Areas in Electroplating

    NASA Technical Reports Server (NTRS)

    Beasley, J. L.

    1985-01-01

    Polyurethane foam provides effective mask in electroplating of copper or nickel. Thin layer of Turco maskant painted on area to be masked: Layer ensures polyurethane foam removed easily after served its purpose. Component A, isocyanate, and component B, polyol, mixed together and brushed or sprayed on mask area. Mixture reacts, yielding polyurethane foam. Foam prevents deposition of nickel or copper on covered area. New method saves time, increases productivity and uses less material than older procedures.

  15. ISABELLE. Volume 3. Experimental areas, large detectors

    SciTech Connect

    Not Available

    1981-01-01

    This section presents the papers which resulted from work in the Experimental Areas portion of the Workshop. The immediate task of the group was to address three topics. The topics were dictated by the present state of ISABELLE experimental areas construction, the possibility of a phased ISABELLE and trends in physics and detectors.

  16. Amplifiers dedicated for large area SiC photodiodes

    NASA Astrophysics Data System (ADS)

    Doroz, P.; Duk, M.; Korwin-Pawlowski, M. L.; Borecki, M.

    2016-09-01

    Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.

  17. Large area flexible solar array design for Space Shuttle application

    NASA Technical Reports Server (NTRS)

    Souza, C. J.

    1980-01-01

    A large area flexible solar array has been designed for Shuttle power augmentation. The solar array utilizes large area, low cost, weldable solar cells. The paper addresses how the unique requirements of this system are implemented into the design. Economic and reliability issues relating to the optimization of a large area, foldable solar array concomitant to the Shuttle/Orbiter system are reviewed.

  18. Priority areas for large mammal conservation in Equatorial Guinea.

    PubMed

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789) elephants and 11,097 (8,719-13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and Río Campo

  19. Knowing good from bad: differential activation of human cortical areas by positive and negative outcomes.

    PubMed

    Nieuwenhuis, Sander; Slagter, Heleen A; von Geusau, Niels J Alting; Heslenfeld, Dirk J; Holroyd, Clay B

    2005-06-01

    Previous research has identified a component of the event-related brain potential (ERP), the feedback-related negativity, that is elicited by feedback stimuli associated with unfavourable outcomes. In the present research we used event-related functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) recordings to test the common hypothesis that this component is generated in the caudal anterior cingulate cortex. The EEG results indicated that our paradigm, a time estimation task with trial-to-trial performance feedback, elicited a large feedback-related negativity (FRN). Nevertheless, the fMRI results did not reveal any area in the caudal anterior cingulate cortex that was differentially activated by positive and negative performance feedback, casting doubt on the notion that the FRN is generated in this brain region. In contrast, we found a number of brain areas outside the posterior medial frontal cortex that were activated more strongly by positive feedback than by negative feedback. These included areas in the rostral anterior cingulate cortex, posterior cingulate cortex, right superior frontal gyrus, and striatum. An anatomically constrained source model assuming equivalent dipole generators in the rostral anterior cingulate, posterior cingulate, and right superior frontal gyrus produced a simulated scalp distribution that corresponded closely to the observed scalp distribution of the FRN. These results support a new hypothesis regarding the neural generators of the FRN, and have important implications for the use of this component as an electrophysiological index of performance monitoring and reward processing.

  20. Doping-dependent THz photoconductivity in large-area graphene

    NASA Astrophysics Data System (ADS)

    Frenzel, Alex; Lui, Chun Hung; Shin, Yong Cheol; Kong, Jing; Gedik, Nuh

    2014-03-01

    We have performed a systematic investigation of the transient terahertz photoconductivity of large-area CVD graphene following femtosecond optical excitation as a function of electrically-tuned carrier density. We observe a dramatic change in the transient response as the photoconductivity changes from positive to negative when the Fermi level is tuned from the charge neutrality point to the electron or hole doped regime. This effect is discussed within the context of the Drude model for free carriers, taking into account the elevated electron and phonon temperatures in photoexcited graphene. Our results demonstrate that previous conflicting measurements of terahertz photoconductivity in epitaxial and CVD graphene arise primarily from their different doping levels. Additionally, our measurements provide a link between ultrafast optical experiments and DC photocurrent measurements.

  1. Large Area Silicon Sheet by EFG

    NASA Technical Reports Server (NTRS)

    Wald, F. V.

    1979-01-01

    Progress made in the development of EFG ribbon growth is discussed. Specific areas covered include: (1) demonstration of multiple growth for ribbons 5 cm wide in runs of 12 and 20 hours duration; (2) a single cartridge crystal growth station was built expanding observational capacity by virtue of an anamorphic optical-video system which allows close observation of the meniscus over 7.5 cm wide, as well as video taping of the ribbon growth process; (3) growth station no.1 achieved reproducible and reliable growth of 7.5 cm wide ribbon at speeds up to 4 cm/min; (4) introduction of the 'mini cold shoe'; (5) increases in cell efficiency due to interface shaping using the 'displaced die' concept; and (6) clarification of the role of gaseous impurities in cartridge furnaces and stabilization of their destabilizing influence on growth.

  2. A large area liquid scintillation multiphoton detector

    NASA Astrophysics Data System (ADS)

    Bharadwaj, V. K.; Cain, M. P.; Caldwell, D. O.; Denby, B. H.; Eisner, A. M.; Joshi, U. P.; Kennett, R. G.; Lu, A.; Morrison, R. J.; Pfost, D. R.; Stuber, H. R.; Summers, D. J.; Yellin, S. J.; Appel, J. A.

    1985-01-01

    A 60 layer lead-liquid scintillator shower detector, which we call the SLIC, has been used for multiphoton detection in the Fermilab tagged photon spectrometer. The detector has an unimpeded active area which is 2.44 m by 4.88 m and is segmented, by means of teflon coated channels, into 3.17 cm wide strips. The 60 layers in depth are broken into three directions of alternating readouts so that three position coordinates are determined for each shower. At present the readouts are made by 334 photomultiplier tubes coupled to BBQ doped wavelength shifter bars which integrate the entire depth of the detector. It is relatively straightforward to increase the number of readouts to include longitudinal segmentation and to increase the segmentation of the outer region which are at present read out two strips to a readout. The energy and position resolutions of isolated showers are about {12%}/{√E} and 3 mm., respectively. The SLIC has been used to study the K-π+π0 decay of the D 0 [1], as well as for electron and muon identification in ψ → e +e - and ψ → μ+μ- plus π0 identification in γp → ψχ [8].

  3. Large-area silicon sheet task

    NASA Technical Reports Server (NTRS)

    Morrison, A. D.

    1982-01-01

    A set of computer models was used to define a growth system configuration that was then built and used to grow web with lower thermally generated stress. Aspects of research in the edge-defined film-fed growth (EFG) method of making Si ribbon are reported. A technique was developed to determine base resistivity and carrier lifetime in semicrystalline wafers. Automated growth of 150 kg of 15 cm-dia ingot material per crucible is reviewed. Scanning transmisson electron microscopy (STEM) and microprobe investigations of processed EFG ribbon are reported. The chemical composition of the large precipitates was studied. The structural arrangement and the electrical activity of distentions or close to the central twin plane in processed material were studied. The electrical and structural properties of grain boundaries in silicon are discussed. Temperature-dependence measurements of zero-bias conductance, a photoconductivity technique, and deep-level transient spectroscopy (DLTS) were developed. A grooving and staining technique, secondary ion mass spectroscopy, and EBIC measurements in scanning electron microscopy were used to study enhanced diffusion of phosphorus at grain boundaries in polycrystaline silicon. The fundamental mechanisms of abrasion and wear and the deformation of Si by a diamond in various fluid environments are described. The efficiency of solar cells made from EFG ribbon and Semix Inc. material is reported.

  4. Negative thermal expansion due to negative area compressibility in TlGaSe2 semiconductor with layered crystalline structure

    NASA Astrophysics Data System (ADS)

    Seyidov, MirHasan Yu.; Suleymanov, Rauf A.

    2010-09-01

    We conducted comparison of the original experimental data of the temperature dependences of thermal expansion in crystals with layered crystalline structure. It is shown that in most crystals with layered structure (graphite, boron nitride, GaSe, GaS, and InSe) the effect of negative thermal expansion can be explained by the specific character of the phonon spectra. It was shown, that in contrast to other crystals with layered structure, negative thermal expansion in the layers' plane of TlGaSe2 is the result of negative area compressibility. We demonstrate that the thermal expansion of TlGaSe2 crystals can be controlled by illumination, external electric field, and thermal annealing. The nature of observed effects and a special mechanism of the negative area compressibility in TlGaSe2 crystals are discussed.

  5. Priority Areas for Large Mammal Conservation in Equatorial Guinea

    PubMed Central

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S.

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437–1,789) elephants and 11,097 (8,719–13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and R

  6. Large-scale negative polarity magnetic fields on the sun and particle-emitting flares

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

    Some observational facts about the large-scale patterns formed by solar negative polarity magnetic fields during the 19th and 20th cycles of solar activity are presented. The close relation of the position of occurrence of very large flares accompanied by cosmic ray and PCA events as well as other phenomena of solar activity during the declining part of the 19th cycle of the regularities in the internal structure of large scale negative polarity features are demonstrated.

  7. INTERIOR VIEW, PREPARING LARGE MOLD IN BOX FLOOR AREA. WORKERS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW, PREPARING LARGE MOLD IN BOX FLOOR AREA. WORKERS JUST FILLED THE FLASK WITH SAND FROM A HIGH VELOCITY MECHANICAL SAND THRUSTER. - Stockham Pipe & Fittings Company, Ductile Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  8. Satellite image collection modeling for large area hazard emergency response

    NASA Astrophysics Data System (ADS)

    Liu, Shufan; Hodgson, Michael E.

    2016-08-01

    Timely collection of critical hazard information is the key to intelligent and effective hazard emergency response decisions. Satellite remote sensing imagery provides an effective way to collect critical information. Natural hazards, however, often have large impact areas - larger than a single satellite scene. Additionally, the hazard impact area may be discontinuous, particularly in flooding or tornado hazard events. In this paper, a spatial optimization model is proposed to solve the large area satellite image acquisition planning problem in the context of hazard emergency response. In the model, a large hazard impact area is represented as multiple polygons and image collection priorities for different portion of impact area are addressed. The optimization problem is solved with an exact algorithm. Application results demonstrate that the proposed method can address the satellite image acquisition planning problem. A spatial decision support system supporting the optimization model was developed. Several examples of image acquisition problems are used to demonstrate the complexity of the problem and derive optimized solutions.

  9. Reproduction, foraging and the negative density-area relationship of a generalist rodent.

    PubMed

    Wilder, Shawn M; Meikle, Douglas B

    2005-07-01

    While many species show positive relationships between population density and habitat patch area, some species consistently show higher densities in smaller patches. Few studies have examined mechanisms that may cause species to have negative density-area relationships. We tested the hypothesis that greater reproduction in edge versus interior habitats and small versus large fragments contributes to higher densities of white-footed mice (Peromyscus leucopus) in small versus large forest fragments. We also examined vegetation structure and foraging tray utilization to evaluate if greater reproduction was a result of higher food availability. There were greater number of litters and proportion of females producing litters in the edge versus interior of forest fragments, which may have contributed to greater population growth rates and higher densities in edge versus interior and small versus large fragments. Data on vegetation structure and giving-up densities of seeds in artificial patches suggest that food availability may be higher in edge versus interior habitats and small versus large fragments. These results, in an area with few or no long-tailed weasels, provide a distinct contrast to the findings of Morris and Davidson (Ecology 81:2061, 2000) who observed lower reproduction in forest edge habitat as a result of high weasel predation, suggesting that specialist predators may be important in affecting the quality of edge habitat. While we cannot exclude the potential contributions of immigration, emigration, and mortality, our data suggest that greater reproduction in edge versus interior habitat is an important factor contributing to higher densities of P. leucopus in small fragments.

  10. Fabrication of Large Area Periodic Nanostructures Using Nanosphere Photolithography

    PubMed Central

    2008-01-01

    Large area periodic nanostructures exhibit unique optical and electronic properties and have found many applications, such as photonic band-gap materials, high dense data storage, and photonic devices. We have developed a maskless photolithography method—Nanosphere Photolithography (NSP)—to produce a large area of uniform nanopatterns in the photoresist utilizing the silica micro-spheres to focus UV light. Here, we will extend the idea to fabricate metallic nanostructures using the NSP method. We produced large areas of periodic uniform nanohole array perforated in different metallic films, such as gold and aluminum. The diameters of these nanoholes are much smaller than the wavelength of UV light used and they are very uniformly distributed. The method introduced here inherently has both the advantages of photolithography and self-assembled methods. Besides, it also generates very uniform repetitive nanopatterns because the focused beam waist is almost unchanged with different sphere sizes.

  11. Plasma and Ion Sources in Large Area Coatings: A Review

    SciTech Connect

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  12. Progress on large-area polarization grating fabrication

    NASA Astrophysics Data System (ADS)

    Miskiewicz, Matthew N.; Kim, Jihwan; Li, Yanming; Komanduri, Ravi K.; Escuti, Michael J.

    2012-06-01

    Over the last several years, we have pioneered liquid crystal polarization gratings (PGs), in both switchable and polymer versions. We have also introduced their use in many applications, including mechanical/non-mechanical laser beam steering and polarization imaging/sensing. Until now, conventional holographic congurations were used to create PGs where the diameter of the active area was limited to 1-2 inches. In this paper, we discuss a new holography setup to fabricate large area PGs using spherical waves as the diverging coherent beams. Various design parameters of this setup are examined for impact on the quality of the recorded PG profile. Using this setup, we demonstrate a large area polymer PG with approximately 66 inch square area, and present detailed characterization.

  13. Large-area metallic photonic lattices for military applications.

    SciTech Connect

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  14. Material balance areas and frequencies for large reprocessing plants

    SciTech Connect

    Burr, T.

    1994-08-01

    It has long been recognized that facilities with a large nuclear material throughput will probably not meet the International Atomic Energy Agency (IAEA) goal for detecting trickle diversion of plutonium over periods of about one year. The reason is that measurement errors for plutonium concentration and for liquid volume are often approximately relative over a fairly wide range of true values. Therefore, large throughput facilities will tend to have large uncertainties assigned to their annual throughput. By the same argument, if frequent balances are performed over small material balance areas, then the uncertainty associated with each balance period for each balance area will be small. However, trickle diversion would still be difficult to detect statistically. Because the IAEA will soon be faced with safeguarding a new large-scale reprocessing plant in Japan, it is timely to reconsider the advantages and disadvantages of performing frequent material balances over small balance areas (individual tanks where feasible). Therefore, in this paper the authors present some simulation results to study the effect of balance frequency on loss detection probability, and further simulation results to study possibilities introduced by choosing small balance areas. They conclude by recommending frequent balances over small areas.

  15. Semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  16. Modeling a Dry Etch Process for Large-Area Devices

    SciTech Connect

    Buss, R.J.; Hebner, G.A.; Ruby, D.S.; Yang, P.

    1999-07-28

    There has been considerable interest in developing dry processes which can effectively replace wet processing in the manufacture of large area photovoltaic devices. Environmental and health issues are a driver for this activity because wet processes generally increase worker exposure to toxic and hazardous chemicals and generate large volumes of liquid hazardous waste. Our work has been directed toward improving the performance of screen-printed solar cells while using plasma processing to reduce hazardous chemical usage.

  17. Identifying Corridors among Large Protected Areas in the United States

    PubMed Central

    Belote, R. Travis; Dietz, Matthew S.; McRae, Brad H.; Theobald, David M.; McClure, Meredith L.; Irwin, G. Hugh; McKinley, Peter S.; Gage, Josh A.; Aplet, Gregory H.

    2016-01-01

    Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current era of rapid climate change. Models that identify suitable linkages between core areas have been used to prioritize potentially important corridors for maintaining functional connectivity. Here, we identify the most “natural” (i.e., least human-modified) corridors between large protected areas in the contiguous Unites States. We aggregated results from multiple connectivity models to develop a composite map of corridors reflecting agreement of models run under different assumptions about how human modification of land may influence connectivity. To identify which land units are most important for sustaining structural connectivity, we used the composite map of corridors to evaluate connectivity priorities in two ways: (1) among land units outside of our pool of large core protected areas and (2) among units administratively protected as Inventoried Roadless (IRAs) or Wilderness Study Areas (WSAs). Corridor values varied substantially among classes of “unprotected” non-core land units, and land units of high connectivity value and priority represent diverse ownerships and existing levels of protections. We provide a ranking of IRAs and WSAs that should be prioritized for additional protection to maintain minimal human modification. Our results provide a coarse-scale assessment of connectivity priorities for maintaining a connected network of protected areas. PMID:27104683

  18. Large area, low cost solar cell development and production readiness

    NASA Technical Reports Server (NTRS)

    Michaels, D.

    1982-01-01

    A process sequence for a large area ( or = 25 sq. cm) silicon solar cell was investigated. Generic cell choice was guided by the expected electron fluence, by the packing factors of various cell envelope designs onto each panel to provide needed voltage as well as current, by the weight constraints on the system, and by the cost goals of the contract.

  19. Large-area Overhead Manipulator for Access of Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multi-axis, cable-driven manipulators have evolved over many years providing large area suspended platform access, programmability, relatively rigid and flexibly-positioned platform control and full six degree of freedom (DOF) manipulation of sensors and tools. We describe innovations for a new six...

  20. An improved method for large-scale preparation of negatively and positively supercoiled plasmid DNA.

    PubMed

    Barth, Marita; Dederich, Debra; Dedon, Peter

    2009-07-01

    A rigorous understanding of the biological function of superhelical tension in cellular DNA requires the development of new tools and model systems for study. To this end, an ethidium bromide[#x02013]free method has been developed to prepare large quantities of either negatively or positively super-coiled plasmid DNA. The method is based upon the known effects of ionic strength on the direction of binding of DNA to an archaeal histone, rHMfB, with low and high salt concentrations leading to positive and negative DNA supercoiling, respectively. In addition to fully optimized conditions for large-scale (>500 microg) supercoiling reactions, the method is advantageous in that it avoids the use of mutagenic ethidium bromide, is applicable to chemically modified plasmid DNA substrates, and produces both positively and negatively supercoiled DNA using a single set of reagents.

  1. Large negatively charged organic host molecules as inhibitors of endonuclease enzymes.

    PubMed

    Tauran, Yannick; Anjard, Christophe; Kim, Beomjoon; Rhimi, Moez; Coleman, Anthony W

    2014-10-07

    Three large negatively charged organic host molecules; β-cyclodextrin sulphate, para-sulphonato-calix[6]arene and para-sulphonato-calix[8]arene have been shown to be effective inhibitors of endonuclease in the low micromolar range, additionally para-sulphonato-calix[8]arene is a partial inhibitor of rhDNase I.

  2. Large-area ALON windows for reconnaissance and armor applications

    NASA Astrophysics Data System (ADS)

    Goldman, Lee M.; Twedt, Richard; Foti, Robyn; Smith, Mark; Sastri, Suri A.

    2009-05-01

    The demand for large ALON® windows has continued to increase since the material transitioned to Surmet Corporation for commercialization. Two applications which represent opposite ends of the requirements spectrum in terms of required optical performance and cost sensitivity are Reconnaissance windows and transparent armor. Consequently, the approaches to producing large area windows for both applications are quite different. While Recce applications require windows of the highest possible optical quality and stringent refractive index homogeneity across the large aperture sizes of Recce sensors, the optical requirements for transparent armor windows are substantially looser. Furthermore, optical performance is paramount for Recce applications while transparent armor applications are more strongly driven by cost considerations. Surmet has developed processes for producing large (i.e., up to ~17x30-in) ALON® window blanks of extremely high optical quality and refractive index homogeneity, for Recce applications. This material has been optically fabricated into finished windows and characterized for transmitted wavefront and homogeneity. Recent results will be presented. Large area transparent armor windows have been produced using a tiling approach. Since transparent armor laminates consist of multiple layers (i.e., ALON/Glass/Polycarbonate) Smaller ALON® tiles can be face bonded onto the underlying glass and polycarbonate layers to produce very large windows. Excellent ballistic results have been obtained using a tiled configuration. Recent results will be presented.

  3. Fire-on-fire interactions in three large wilderness areas

    NASA Astrophysics Data System (ADS)

    Teske, Casey C.

    Current knowledge about wildfire occurrence is not complete. Fire researchers and managers hold the assumption that previous wildfires affect subsequent wildfires; however, research regarding the interactions of large wildfires at their common boundaries is missing from the literature. This research focuses on understanding the influence of previous large wildfires on subsequent large wildfires in three wilderness areas: The Greater Bob Marshall, the Selway-Bitterroot, and the Frank Church. Data from the Monitoring Trends in Burn Severity (MTBS) project, which mapped large wildfires in the western United States occurring since 1984, are used for the research. The combination of using wilderness areas and remotely sensed images allows an objective and consistent analysis of fire-on-fire interaction that is extensive in both time and space. Standardized methods for analyzing fire interactions do not currently exist, therefore methods were developed, tested, and refined to describe, quantify, and compare once-burned and re-burned locations within a subset of ten fires in terms of size, location, timing between fires, and severity. These methods were then used to address the question of whether re-burns occur within each of the three wilderness areas. Edge and re-burn characteristics were also derived and quantified. Results were statistically and empirically compared to randomized fire intersections and to published fire history research for each area. Although a low proportion of each study area burns or re-burns, when a new fire encounters a previous fire it re-burns onto the previously burned area approximately 80% of the time. Current large wildfires are behaving in a typical fashion, although on some landscapes the amount of re-burn is not different from what would be expected due to chance. Lastly, the complexity of the post-fire landscape was assessed using texture metrics. Pre-fire and post-fire landscapes were shown to be different, with post-fire landscapes

  4. Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report

    NASA Technical Reports Server (NTRS)

    1976-01-01

    It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.

  5. Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large r

    SciTech Connect

    McDonald, John

    2014-11-01

    Planck favours a negative running of the spectral index, with the likelihood being dominated by low multipoles l ∼< 50 and no preference for running at higher l. A negative spectral index is also necessary for the 2- Planck upper bound on the tensor-to-scalar ratio r to be consistent with values significantly larger than 0.1. Planck has also observed a hemispherical asymmetry of the CMB power spectrum, again mostly at low multipoles. Here we consider whether the physics responsible for the hemispherical asymmetry could also account for the negative running of the spectral index and the consistency of Planck with a large value of r. A negative running of the spectral index can be generated if the hemispherical asymmetry is due to a scale- and space-dependent modulation which suppresses the CMB power spectrum at low multipoles. We show that the observed hemispherical asymmetry at low l can be generated while satisfying constraints on the asymmetry at higher l and generating a negative spectral index of the right magnitude to account for the Planck observation and to allow Planck to be consistent with a large value of r.

  6. Characteristics of plasma grid bias in large-scaled negative ion source

    SciTech Connect

    Kisaki, M.; Tsumori, K.; Ikeda, K.; Nakano, H.; Osakabe, M.; Nagaoka, K.; Takeiri, Y.; Kaneko, O.

    2014-02-15

    The electron density was measured at various bias voltages to understand how the plasma grid bias affects the electron near the plasma grid in large-scaled negative ion sources. It was found that the response of the electron to the bias voltage changes depending on negative ion production processes. The electron density remarkably decreases with increasing the bias voltage in the pure-volume plasma. On the other hand, the electron density depends on the bias voltage weakly in the Cs-seeded plasma. In addition, it was observed that the response of the co-extracted electron current to the bias voltage has similar trend to that of the electron density.

  7. Spatially explicit shallow landslide susceptibility mapping over large areas

    USGS Publications Warehouse

    Bellugi, Dino; Dietrich, William E.; Stock, Jonathan D.; McKean, Jim; Kazian, Brian; Hargrove, Paul

    2011-01-01

    Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so it has generated downscaled precipitation maps for the storm. To predict the corresponding pattern of shallow landslide susceptibility across the state, we have used the model Shalstab (a coupled steady state runoff and infinite slope stability model) which susceptibility spatially explicit estimates of relative potential instability. Such slope stability models that include the effects of subsurface runoff on potentially destabilizing pore pressure evolution require water routing and hence the definition of upslope drainage area to each potential cell. To calculate drainage area efficiently over a large area we developed a parallel framework to scale-up Shalstab and specifically introduce a new efficient parallel drainage area algorithm which produces seamless results. The single seamless shallow landslide susceptibility map for all of California was accomplished in a short run time, and indicates that much larger areas can be efficiently modelled. As landslide maps generally over predict the extent of instability for any given storm. Local empirical data on the fraction of predicted unstable cells that failed for observed rainfall intensity can be used to specify the likely extent of hazard for a given storm. This suggests that campaigns to collect local precipitation data and detailed shallow landslide location maps after major storms could be used to calibrate models and improve their use in hazard assessment for individual storms.

  8. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  9. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  10. Women Workers in Regional Areas and in Large States and Metropolitan Areas, 1971.

    ERIC Educational Resources Information Center

    Employment Standards Administration (DOL), Washington, DC. Women's Bureau.

    Data from the Bureau of Labor Statistics has been summarized on labor force participation and unemployment rates in 1971, of women 16 years of age and over, in the various census regions of the United States and in 10 large States and 20 large Standard Metropolitan Statistical Areas (SMSA's); separate data also have been summarized for women of…

  11. Large area, dense silicon nanowire array chemical sensors

    SciTech Connect

    Talin, A. Alec; Hunter, Luke L.; Leonard, Francois; Rokad, Bhavin

    2006-10-09

    The authors present a simple top-down approach based on nanoimprint lithography to create dense arrays of silicon nanowires over large areas. Metallic contacts to the nanowires and a bottom gate allow the operation of the array as a field-effect transistor with very large on/off ratios. When exposed to ammonia gas or cyclohexane solutions containing nitrobenzene or phenol, the threshold voltage of the field-effect transistor is shifted, a signature of charge transfer between the analytes and the nanowires. The threshold voltage shift is proportional to the Hammett parameter and the concentration of the nitrobenzene and phenol analytes.

  12. A large area, high gain Micro Gap Chamber

    NASA Astrophysics Data System (ADS)

    Angelini, F.; Bellazzini, R.; Bozzo, M.; Brez, A.; Massai, M. M.; Raffo, R.; Spandre, G.; Spezziga, M.; Toropin, A.

    1995-02-01

    A new approach to the construction of the Micro Gap Chamber is presented. A 10 × 10 cm 2 MGC has been built using a 8 μm thick polyimide layer as anode-cathode insulator. Studies on gas gain, uniformity of response along the strip and charging-up have been carried out in laboratory by using X-ray sources. Very large proportional gains, up to ˜ 210 4, have been reached working with gas mixtures based on Ne-DME. The simplified technology for the detector fabrication opens the possibility to produce very large area MGCs.

  13. Characterization of Large Area APDs for the EXO-200 Detector

    SciTech Connect

    Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C.Y.; Tenev, V.; Ackerman, N.; Akimov, D.; Auger, M.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Conley, R.; Cook, S.; deVoe, R.; Dolinski, M.J.; Fairbank, W., Jr.; Farine, J.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  14. High Energy Astrophysics with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  15. Development of large-area CZT detector systems

    NASA Astrophysics Data System (ADS)

    Kuvvetli, Irfan; Budtz-Joergensen, Carl C.; Westergaard, Niels J.; Jonasson, Per; van Pamelen, Mike A.; Reglero, Victor; Eyles, Christopher J.; Neubert, Torsten

    1999-10-01

    DSRI has initiated a development program of CZT x-ray and gamma ray detectors employing strip readout techniques. A dramatic improvement of the energy response was found operating the detectors as so-called drift detectors. For the electronic readout, modern ASIC chips were investigated. Modular design and the low power electronics will make large area detectors using the drift strip method feasible. The performance of a prototype CZT system will be presented and discussed.

  16. Gravure printing of graphene for large-area flexible electronics.

    PubMed

    Secor, Ethan B; Lim, Sooman; Zhang, Heng; Frisbie, C Daniel; Francis, Lorraine F; Hersam, Mark C

    2014-07-09

    Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.

  17. Pilot Production of Large Area Microchannel Plates and Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Minot, M.; Adams, B.; Abiles, M.; Bond, J.; Craven, C.; Cremer, T.; Foley, M.; Lyashenko, A.; Popecki, M.; Stochaj, M.; Worstell, W.; Elam, J.; Mane, A.; Siegmund, O.; Ertley, C.

    2016-09-01

    Pilot production performance is reported for large area atomic layer deposition (ALD) coated microchannel plates (ALD-GCA-MCPs) and for Large Area Picosecond Photodetectors (LAPPD™) which incorporate them. "Hollowcore" glass capillary array (GCA) substrates are coated with ALD resistive and emissive layers to form the ALDGCA- MCPs, an approach that facilitates independent selection of glass substrates that are mechanically stronger and that have lower levels of radioactive alkali elements compared to conventional MCP lead glass, reducing background noise[1,2,3,4]. ALD-GCA-MCPs have competitive gain ( 104 each or 107 for a chevron pair ), enhanced lifetime and gain stability (7 C cm-2 of charge extraction), reduced background levels (0.028 events cm-2 sec-1) and low gamma-ray detection efficiency. They can be fabricated in large area (20cm X 20 cm) planar and curved formats suitable for use in high radiation environment applications, including astronomy, space instrumentation, and remote night time sensing. The LAPPD™ photodetector incorporates these ALD-GCA-MCPs in an all-glass hermetic package with top and bottom plates and sidewalls made of borosilicate float glass. Signals are generated by a bi-alkali Na2KSb photocathode, amplified with a stacked chevron pair of ALD-GCA-MCPs. Signals are collected on RF strip-line anodes integrated into to the bottom plates which exit the detector via pin-free hermetic seals under the side walls [5]. Tests show that LAPPDTMs have electron gains greater than 107, submillimeter spatial resolution for large (multiphoton) pulses and several mm for single photons, time resolution less than 50 picoseconds for single photons, predicted resolution less than 5 picoseconds for large pulses, high stability versus charge extraction[6], and good uniformity for applications including astrophysics, neutron detection, high energy physics Cherenkov light detection, and quantum-optical photon-correlation experiments.

  18. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    SciTech Connect

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-02-05

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

  19. Large areas elemental mapping by ion beam analysis techniques

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Rodrigues, C. L.; Curado, J. F.; Allegro, P.; Moro, M. V.; Campos, P. H. O. V.; Santos, S. B.; Kajiya, E. A. M.; Rizzutto, M. A.; Added, N.; Tabacniks, M. H.

    2015-07-01

    The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

  20. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Lösel, Philipp; Atlas Muon Collaboration

    2016-07-01

    Resistive strip Micromegas detectors have been tested extensively as small detectors of about 10×10 cm2 in size and they work reliably at high rates of 100 kHz/cm2 and above. Tracking resolution well below 100 μm has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m2 in size. To investigate possible differences between small and large detectors, a 1 m2 detector with 2048 resistive strips at a pitch of 450 μm was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4×2.2 m2 large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm×93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, determination of signal propagation along the 1 m long anode strips and calibration of the position of the anode strips.

  1. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Brown, Courtney; Krishnan, Vasaant

    2014-04-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey is answering critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH is also detecting many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 250 hours to complete Phase 1 of the SPLASH project, which is mapping 152 square degrees in the inner Galactic Plane, including the Galactic Centre.

  2. Double hysteresis loops and large negative and positive electrocaloric effects in tetragonal ferroelectrics.

    PubMed

    Wu, Hong-Hui; Zhu, Jiaming; Zhang, Tong-Yi

    2015-10-07

    Phase field modelling and thermodynamic analysis are employed to investigate depolarization and compression induced large negative and positive electrocaloric effects (ECEs) in ferroelectric tetragonal crystalline nanoparticles. The results show that double-hysteresis loops of polarization versus electric field dominate at temperatures below the Curie temperature of the ferroelectric material, when the mechanical compression exceeds a critical value. In addition to the mechanism of pseudo-first-order phase transition (PFOPT), the double-hysteresis loops are also caused by the abrupt rise of macroscopic polarization from the abc phase to the c phase or the sudden fall of macroscopic polarization from the c phase to the abc phase when the temperature increases. This phenomenon is called the electric-field-induced-pseudo-phase transition (EFIPPT) in the present study. Similar to the two types of PFOPTs, the two types of EFIPPTs cause large negative and positive ECEs, respectively, and give the maximum absolute values of negative and positive adiabatic temperature change (ATC ΔT). The temperature associated with the maximum absolute value of negative ATC ΔT is lower than that associated with the maximum positive ATC ΔT. Both maximum absolute values of ATC ΔTs change with the variation in the magnitude of an applied electric field and depend greatly on the compression intensity.

  3. Dynamics of Disagreement: Large-Scale Temporal Network Analysis Reveals Negative Interactions in Online Collaboration

    NASA Astrophysics Data System (ADS)

    Tsvetkova, Milena; García-Gavilanes, Ruth; Yasseri, Taha

    2016-11-01

    Disagreement and conflict are a fact of social life. However, negative interactions are rarely explicitly declared and recorded and this makes them hard for scientists to study. In an attempt to understand the structural and temporal features of negative interactions in the community, we use complex network methods to analyze patterns in the timing and configuration of reverts of article edits to Wikipedia. We investigate how often and how fast pairs of reverts occur compared to a null model in order to control for patterns that are natural to the content production or are due to the internal rules of Wikipedia. Our results suggest that Wikipedia editors systematically revert the same person, revert back their reverter, and come to defend a reverted editor. We further relate these interactions to the status of the involved editors. Even though the individual reverts might not necessarily be negative social interactions, our analysis points to the existence of certain patterns of negative social dynamics within the community of editors. Some of these patterns have not been previously explored and carry implications for the knowledge collection practice conducted on Wikipedia. Our method can be applied to other large-scale temporal collaboration networks to identify the existence of negative social interactions and other social processes.

  4. Dynamics of Disagreement: Large-Scale Temporal Network Analysis Reveals Negative Interactions in Online Collaboration

    PubMed Central

    Tsvetkova, Milena; García-Gavilanes, Ruth; Yasseri, Taha

    2016-01-01

    Disagreement and conflict are a fact of social life. However, negative interactions are rarely explicitly declared and recorded and this makes them hard for scientists to study. In an attempt to understand the structural and temporal features of negative interactions in the community, we use complex network methods to analyze patterns in the timing and configuration of reverts of article edits to Wikipedia. We investigate how often and how fast pairs of reverts occur compared to a null model in order to control for patterns that are natural to the content production or are due to the internal rules of Wikipedia. Our results suggest that Wikipedia editors systematically revert the same person, revert back their reverter, and come to defend a reverted editor. We further relate these interactions to the status of the involved editors. Even though the individual reverts might not necessarily be negative social interactions, our analysis points to the existence of certain patterns of negative social dynamics within the community of editors. Some of these patterns have not been previously explored and carry implications for the knowledge collection practice conducted on Wikipedia. Our method can be applied to other large-scale temporal collaboration networks to identify the existence of negative social interactions and other social processes. PMID:27808267

  5. An ultra large negative dispersion regular octagonal PCF with liquid infiltration

    NASA Astrophysics Data System (ADS)

    Kong, Xiangmin; Li, Xinlu; Jiang, Xingfang; Tang, Bin

    2015-10-01

    For solving the problem of dispersion in fiber communication, this article designed a ultra large negative dispersion regular octagonal PCF with liquid infiltration. The effects of air-hole diameter (d), layer-to-layer spacing (Λ) and refractive index of the infiltrating liquid (nL) on dispersion have been obtained based on Finite Element Method (FEM) by using COMSOL Multiphysics. The results show that with an increase of nL, the dispersion gets blue-shifted and the negative dispersion will increase. However, with the increase of Λ, the dispersion is red-shifted and the negative dispersion will reduce. Again, with the increase of d, the dispersion is red-shifted but with an augment of negative dispersion. This paper's theoretical study shows a high negative dispersion of -13000ps/(nm·km) around 1550nm when d=1.000μm, Λ=1.500μm and nL=1.374. The Dispersion Compensating Fiber (DCF) can effectively compensate the single mode fiber G. 652, which has been widely used. One meter the DCF can compensate 650 meters G. 652.

  6. Large-area photogrammetry based testing of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Poozesh, Peyman; Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter; Harvey, Eric; Yarala, Rahul

    2017-03-01

    An optically based sensing system that can measure the displacement and strain over essentially the entire area of a utility-scale blade leads to a measurement system that can significantly reduce the time and cost associated with traditional instrumentation. This paper evaluates the performance of conventional three dimensional digital image correlation (3D DIC) and three dimensional point tracking (3DPT) approaches over the surface of wind turbine blades and proposes a multi-camera measurement system using dynamic spatial data stitching. The potential advantages for the proposed approach include: (1) full-field measurement distributed over a very large area, (2) the elimination of time-consuming wiring and expensive sensors, and (3) the need for large-channel data acquisition systems. There are several challenges associated with extending the capability of a standard 3D DIC system to measure entire surface of utility scale blades to extract distributed strain, deflection, and modal parameters. This paper only tries to address some of the difficulties including: (1) assessing the accuracy of the 3D DIC system to measure full-field distributed strain and displacement over the large area, (2) understanding the geometrical constraints associated with a wind turbine testing facility (e.g. lighting, working distance, and speckle pattern size), (3) evaluating the performance of the dynamic stitching method to combine two different fields of view by extracting modal parameters from aligned point clouds, and (4) determining the feasibility of employing an output-only system identification to estimate modal parameters of a utility scale wind turbine blade from optically measured data. Within the current work, the results of an optical measurement (one stereo-vision system) performed on a large area over a 50-m utility-scale blade subjected to quasi-static and cyclic loading are presented. The blade certification and testing is typically performed using International

  7. Large area flexible SERS active substrates using engineered nanostructures

    NASA Astrophysics Data System (ADS)

    Chung, Aram J.; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as

  8. Large and tunable negative refractive index via electromagnetically induced chirality in a semiconductor quantum well nanostructure

    NASA Astrophysics Data System (ADS)

    Zhao, Sh.-C.; Zhang, Sh.-Y.; Xu, Y.-Y.

    2014-11-01

    Large and tunable negative refractive index (NRI) via electromagnetically induced chirality is demonstrated in a semiconductor quantum wells (SQWs) nanostructure by using the reported experimental parameters in J.F. Dynes et al., Phys. Rev. Lett. 94, 157403 (2005). It is found: the large and controllable NRI with alterable frequency regions is obtained when the coupling laser field and the relative phase are modulated, which will increase the flexibility and possibility of implementing NRI in the SQWs nanostructure. The scheme rooted in the experimental results may lead a new avenue to NRI material in solid-state nanostructure.

  9. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    PubMed Central

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  10. Application issues for large-area electrochromic windows incommercial buildings

    SciTech Connect

    Lee, Eleanor S.; DiBartolomeo, D.L.

    2000-05-01

    Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in significant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in-situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial buildings. The visible transmittance (Tv) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demonstrate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24 percent less compared to the 11 percent-glazing, with improved interior brightness levels. Daily lighting energy use was 3 percent less to 13 percent more compared to the 38 percent-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and visual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT

  11. Solvothermal synthesis of ceria nanoparticles with large surface areas

    SciTech Connect

    Hosokawa, S.; Shimamura, K.; Inoue, M.

    2011-11-15

    Highlights: {yields} Thermal decomposition of Ce(C{sub 7}H{sub 15}COO){sub 3}.xH{sub 2}O synthesized by solvothermal method. {yields} CeO{sub 2} having an extremely large surface area of 180 m{sup 2}/g. {yields} High catalytic activity of Ru catalyst supported on the CeO{sub 2} having high surface area. -- Abstract: Ceria nanoparticles were obtained by the calcination of precursors synthesised via the solvothermal reaction of cerium acetate. The CeO{sub 2} samples obtained by the thermal decomposition of Ce(C{sub 7}H{sub 15}COO){sub 3}.xH{sub 2}O synthesised by solvothermal reaction in 1,4-butanediol in the presence of octanoic acid had an extremely large surface area of 180 m{sup 2}/g. The Ru catalyst supported on this CeO{sub 2} sample showed a high catalytic activity for benzyl alcohol oxidation.

  12. Large area flexible SERS active substrates using engineered nanostructures.

    PubMed

    Chung, Aram J; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.

  13. Dark Matter Searches with the Fermi Large Area Telescope

    SciTech Connect

    Meurer, Christine

    2008-12-24

    The Fermi Gamma-Ray Space Telescope, successfully launched on June 11th, 2008, is the next generation satellite experiment for high-energy gamma-ray astronomy. The main instrument, the Fermi Large Area Telescope (LAT), with a wide field of view (>2 sr), a large effective area (>8000 cm{sup 2} at 1 GeV), sub-arcminute source localization, a large energy range (20 MeV-300 GeV) and a good energy resolution (close to 8% at 1 GeV), has excellent potential to either discover or to constrain a Dark Matter signal. The Fermi LAT team pursues complementary searches for signatures of particle Dark Matter in different search regions such as the galactic center, galactic satellites and subhalos, the milky way halo, extragalactic regions as well as the search for spectral lines. In these proceedings we examine the potential of the LAT to detect gamma-rays coming from Weakly Interacting Massive Particle annihilations in these regions with special focus on the galactic center region.

  14. MILDOS-AREA: An enhanced version of MILDOS for large-area sources

    SciTech Connect

    Yuan, Y.C.; Wang, J.H.C.; Zielen, A.

    1989-06-01

    The MILDOS-AREA computer code is a modified version of the MILDOS code, which estimates the radiological impacts of airborne emissions from uranium mining and milling facilities or any other large-area source involving emissions of radioisotopes of the uranium-238 series. MILDOS-AREA is designed for execution on personal computers. The modifications incorporated in the MILDOS-AREA code provide enhanced capabilities for calculating doses from large-area sources and update dosimetry calculations. The major revision from the original MILDOS code is the treatment of atmospheric dispersion from area sources: MILDOS-AREA substitutes a finite element integration approach for the virtual-point method (the algorithm used in the original MILDOS code) when specified by the user. Other revisions include the option of using Martin-Tickvart dispersion coefficients in place of Briggs coefficients for a given source, consideration of plume reflection, and updated internal dosimetry calculations based on the most recent recommendations of the International Commission on Radiation Protection and the age-specific dose calculation methodology developed by Oak Ridge National Laboratory. This report also discusses changes in computer code structure incorporated into MILDOS-AREA, summarizes data input requirements, and provides instructions for installing and using the program on personal computers. 15 refs., 9 figs., 26 tabs.

  15. A large-area gamma-ray imaging telescope system

    NASA Technical Reports Server (NTRS)

    Koch, D. G.

    1983-01-01

    The concept definition of using the External Tank (ET) of the Space Shuttle as the basis for constructing a large area gamma ray imaging telescope in space is detailed. The telescope will be used to locate and study cosmic sources of gamma rays of energy greater than 100 MeV. Both the telescope properties and the means whereby an ET is used for this purpose are described. A parallel is drawn between those systems that would be common to both a Space Station and this ET application. In addition, those systems necessary for support of the telescope can form the basis for using the ET as part of the Space Station. The major conclusions of this concept definition are that the ET is ideal for making into a gamma ray telescope, and that this telescope will provide a substantial increase in collecting area.

  16. Large Area Crop Inventory Experiment (LACIE). Phase 2 evaluation report

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Documentation of the activities of the Large Area Crop Inventory Experiment during the 1976 Northern Hemisphere crop year is presented. A brief overview of the experiment is included as well as phase two area, yield, and production estimates for the United States Great Plains, Canada, and the Union of Soviet Socialist Republics spring winter wheat regions. The accuracies of these estimates are compared with independent government estimates. Accuracy assessment of the United States Great Plains yardstick region based on a through blind sight analysis is given, and reasons for variations in estimating performance are discussed. Other phase two technical activities including operations, exploratory analysis, reporting, methods of assessment, phase three and advanced system design, technical issues, and developmental activities are also included.

  17. Large area low-cost space solar cell development

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Cioni, J. L.

    1982-01-01

    A development program to produce large-area (5.9 x 5.9 cm) space quality silicon solar cells with a cost goal of 30 $/watt is descibed. Five cell types under investigation include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm-cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover-glass simultaneously is being developed. A description of cell developments by Applied Solar Energy Corp., Spectrolab and Spire is included. Results are given for cell and array tests, performed by Lockheed, TRW and NASA. Future large solar arrays that might use cells of this type are discussed.

  18. The Gamma-ray Large Area Space Telescope (GLAST)

    NASA Technical Reports Server (NTRS)

    Ritz, Steve

    2008-01-01

    The Gamma-ray Large Area space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view will make it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its upcoming launch, GLAST will open a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations. In addition to the science opportunities, this talk includes a description of the instruments, the opportunities for guest investigators, and the mission status.

  19. The world of large-area glazing and displays

    NASA Astrophysics Data System (ADS)

    Lampert, Carl M.

    1999-10-01

    This work covers advances in large-area switchable glazing and flat panel displays. Large flat panels and glazing are being developed by a number of company and university groups. Certain novel flat panels display are made for electronic paper applications. Switchable glazing offers a new way of visualizing the function of a window. Switchable glazing can have a range of adjustable visible properties and shading coefficients. Technologies covered for glazing are electrochromism, suspended particles, encapsulated liquid crystals. Technologies being developed for electronic paper and certain flat display panels include electrophoretics, liquid crystals and bichromal balls. Beyond glazing applications, products based on this technology are flexible displays, electronic paper, switchable modulators, mirrors, and eyeglasses. This study covers developments from several companies including the one square meter electrochromic glazing made by Pilkington/Flabeg and Asahi/Nippon Mitsubishi Oil.

  20. LACIE large area acreage estimation. [United States of America

    NASA Technical Reports Server (NTRS)

    Chhikara, R. S.; Feiveson, A. H. (Principal Investigator)

    1979-01-01

    A sample wheat acreage for a large area is obtained by multiplying its small grains acreage estimate as computed by the classification and mensuration subsystem by the best available ratio of wheat to small grains acreages obtained from historical data. In the United States, as in other countries with detailed historical data, an additional level of aggregation was required because sample allocation was made at the substratum level. The essential features of the estimation procedure for LACIE countries are included along with procedures for estimating wheat acreage in the United States.

  1. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  2. Fermi Large Area Telescope Bright Gamma-ray Source List

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bastieri, Denis; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  3. Large Area Crop Inventory Experiment (LACIE). Executive summary

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The author has identified the following significant results. The Large Area Crop Inventory Experiment (LACIE), completed June 30, 1978, has met the USDA at-harvest goals (90% accuracy with a 90% confidence level) in the US Great Plains and U.S.S.R. for two consecutive years. In addition, in the U.S.S.R., LACIE indicated a shortfall in the '76-'77 wheat crop about two months prior to harvest, thus demonstrating the capability of LACIE to make accurate preharvest estimates.

  4. Method of manufacturing a large-area segmented photovoltaic module

    DOEpatents

    Lenox, Carl

    2013-11-05

    One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

  5. Large-Scale Compton Imaging for Wide-Area Surveillance

    SciTech Connect

    Lange, D J; Manini, H A; Wright, D M

    2006-03-01

    We study the performance of a large-scale Compton imaging detector placed in a low-flying aircraft, used to search wide areas for rad/nuc threat sources. In this paper we investigate the performance potential of equipping aerial platforms with gamma-ray detectors that have photon sensitivity up to a few MeV. We simulate the detector performance, and present receiver operating characteristics (ROC) curves for a benchmark scenario using a {sup 137}Cs source. The analysis uses a realistic environmental background energy spectrum and includes air attenuation.

  6. Large-area settlement pattern recognition from Landsat-8 data

    NASA Astrophysics Data System (ADS)

    Wieland, Marc; Pittore, Massimiliano

    2016-09-01

    The study presents an image processing and analysis pipeline that combines object-based image analysis with a Support Vector Machine to derive a multi-layered settlement product from Landsat-8 data over large areas. 43 image scenes are processed over large parts of Central Asia (Southern Kazakhstan, Kyrgyzstan, Tajikistan and Eastern Uzbekistan). The main tasks tackled by this work include built-up area identification, settlement type classification and urban structure types pattern recognition. Besides commonly used accuracy assessments of the resulting map products, thorough performance evaluations are carried out under varying conditions to tune algorithm parameters and assess their applicability for the given tasks. As part of this, several research questions are being addressed. In particular the influence of the improved spatial and spectral resolution of Landsat-8 on the SVM performance to identify built-up areas and urban structure types are evaluated. Also the influence of an extended feature space including digital elevation model features is tested for mountainous regions. Moreover, the spatial distribution of classification uncertainties is analyzed and compared to the heterogeneity of the building stock within the computational unit of the segments. The study concludes that the information content of Landsat-8 images is sufficient for the tested classification tasks and even detailed urban structures could be extracted with satisfying accuracy. Freely available ancillary settlement point location data could further improve the built-up area classification. Digital elevation features and pan-sharpening could, however, not significantly improve the classification results. The study highlights the importance of dynamically tuned classifier parameters, and underlines the use of Shannon entropy computed from the soft answers of the SVM as a valid measure of the spatial distribution of classification uncertainties.

  7. Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

    PubMed Central

    Yokota, Tomoyuki; Inoue, Yusuke; Terakawa, Yuki; Reeder, Jonathan; Kaltenbrunner, Martin; Ware, Taylor; Yang, Kejia; Mabuchi, Kunihiko; Murakawa, Tomohiro; Sekino, Masaki; Voit, Walter; Sekitani, Tsuyoshi; Someya, Takao

    2015-01-01

    We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature. PMID:26554008

  8. Ultraflexible, large-area, physiological temperature sensors for multipoint measurements.

    PubMed

    Yokota, Tomoyuki; Inoue, Yusuke; Terakawa, Yuki; Reeder, Jonathan; Kaltenbrunner, Martin; Ware, Taylor; Yang, Kejia; Mabuchi, Kunihiko; Murakawa, Tomohiro; Sekino, Masaki; Voit, Walter; Sekitani, Tsuyoshi; Someya, Takao

    2015-11-24

    We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature.

  9. Large-Area Zone Plate Fabrication with Optical Lithography

    SciTech Connect

    Denbeaux, G.

    2011-09-09

    Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/{Delta}E = 700[1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/{Delta}E = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

  10. Deterministic composite nanophotonic lattices in large area for broadband applications

    PubMed Central

    Xavier, Jolly; Probst, Jürgen; Becker, Christiane

    2016-01-01

    Exotic manipulation of the flow of photons in nanoengineered materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced broadband photonic and plasmonic technologies for spectrally tailorable integrated biosensing, nanostructured thin film solarcells, white light emitting diodes, novel plasmonic ensembles etc. Through a generic deterministic nanotechnological route here we show subwavelength-scale silicon (Si) nanostructures on nanoimprinted glass substrate in large area (4 cm2) with advanced functional features of aperiodic composite nanophotonic lattices. These nanophotonic aperiodic lattices have easily tailorable supercell tiles with well-defined and discrete lattice basis elements and they show rich Fourier spectra. The presented nanophotonic lattices are designed functionally akin to two-dimensional aperiodic composite lattices with unconventional flexibility- comprising periodic photonic crystals and/or in-plane photonic quasicrystals as pattern design subsystems. The fabricated composite lattice-structured Si nanostructures are comparatively analyzed with a range of nanophotonic structures with conventional lattice geometries of periodic, disordered random as well as in-plane quasicrystalline photonic lattices with comparable lattice parameters. As a proof of concept of compatibility with advanced bottom-up liquid phase crystallized (LPC) Si thin film fabrication, the experimental structural analysis is further extended to double-side-textured deterministic aperiodic lattice-structured 10 μm thick large area LPC Si film on nanoimprinted substrates. PMID:27941869

  11. Large area single crystal (0001) oriented MoS2

    NASA Astrophysics Data System (ADS)

    Laskar, Masihhur R.; Ma, Lu; Kannappan, Santhakumar; Sung Park, Pil; Krishnamoorthy, Sriram; Nath, Digbijoy N.; Lu, Wu; Wu, Yiying; Rajan, Siddharth

    2013-06-01

    Layered metal dichalcogenide materials are a family of semiconductors with a wide range of energy band gaps and properties, the potential for exciting physics and technology applications. However, obtaining high crystal quality thin films over a large area remains a challenge. Here we show that chemical vapor deposition (CVD) can be used to achieve large area single crystal Molybdenum Disulfide (MoS2) thin films. Growth temperature and choice of substrate were found to critically impact the quality of film grown, and high temperature growth on (0001) oriented sapphire yielded highly oriented single crystal MoS2 films. Films grown under optimal conditions were found to be of high structural quality from high-resolution X-ray diffraction, transmission electron microscopy, and Raman measurements, approaching the quality of reference geological MoS2. Photoluminescence and electrical measurements confirmed the growth of optically active MoS2 with a low background carrier concentration, and high mobility. The CVD method reported here for the growth of high quality MoS2 thin films paves the way towards growth of a variety of layered 2D chalcogenide semiconductors and their heterostructures.

  12. An advanced open path atmospheric pollution monitor for large areas

    SciTech Connect

    Taylor, L.; Suhre, D.; Mani, S.

    1996-12-31

    Over 100 million gallons of radioactive and toxic waste materials generated in weapon materials production are stored in 322 tanks buried within large areas at DOE sites. Toxic vapors occur in the tank headspace due to the solvents used and chemical reactions within the tanks. To prevent flammable or explosive concentration of volatile vapors, the headspace are vented, either manually or automatically, to the atmosphere when the headspace pressure exceeds preset values. Furthermore, 67 of the 177 tanks at the DOE Hanford Site are suspected or are known to be leaking into the ground. These underground storage tanks are grouped into tank farms which contain closely spaced tanks in areas as large as 1 km{sup 2}. The objective of this program is to protect DOE personnel and the public by monitoring the air above these tank farms for toxic air pollutants without the monitor entering the tanks farms, which can be radioactive. A secondary objective is to protect personnel by monitoring the air above buried 50 gallon drums containing moderately low radioactive materials but which could also emit toxic air pollutants.

  13. High Temperature Thermoelectric Device Concept Using Large Area PN Junctions

    NASA Astrophysics Data System (ADS)

    Chavez, R.; Angst, S.; Hall, J.; Stoetzel, J.; Kessler, V.; Bitzer, L.; Maculewicz, F.; Benson, N.; Wiggers, H.; Wolf, D.; Schierning, G.; Schmechel, R.

    2014-06-01

    A new high temperature thermoelectric device concept using large area nanostructured silicon p-type and n-type ( PN) junctions is presented. In contrast to conventional thermoelectric generators, where the n-type and p-type semiconductors are connected electrically in series and thermally in parallel, we experimentally demonstrate a device concept in which a large area PN junction made from highly doped densified silicon nanoparticles is subject to a temperature gradient parallel to the PN interface. In the proposed device concept, the electrical contacts are made at the cold side eliminating the hot side substrate and difficulties that go along with high temperature electrical contacts. This concept allows temperature gradients greater than 300 K to be experimentally applied with hot side temperatures larger than 800 K. Electronic properties of the PN junctions and power output characterizations are presented. A fundamental working principle is discussed using a particle network model with temperature and electric fields as variables, and which considers electrical conductivity and thermal conductivity according to Fourier's law, as well as Peltier and Seebeck effects.

  14. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class; pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  15. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2006-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST) will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class, pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  16. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered p ulsars. As the only presently known galactic GeV source class, pulsar s will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsar s, including millisecond pulsars, giving much better statistics for e lucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric partic le acceleration and radiation mechanisms, by comparing data with theo retical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all un identified EGRET sources, to possibly uncover more radio-quiet Geming a-like pulsars.

  17. The GLAST Large Area Telescope Detector Performance Monitoring

    SciTech Connect

    Borgland, A. W.; Charles, E.

    2007-07-12

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration and Test and Commissioning of the instrument on ground.

  18. The GLAST Large Area Telescope Detector Performance Monitoring

    SciTech Connect

    Borgland, A.W.; Charles, E.; /SLAC

    2007-10-16

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration & Test and Commissioning of the instrument on ground.

  19. The GLAST Large Area Telescope Detector Performance Monitoring

    NASA Astrophysics Data System (ADS)

    Borgland, A. W.; Charles, E.

    2007-07-01

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration & Test and Commissioning of the instrument on ground.

  20. Deterministic composite nanophotonic lattices in large area for broadband applications

    NASA Astrophysics Data System (ADS)

    Xavier, Jolly; Probst, Jürgen; Becker, Christiane

    2016-12-01

    Exotic manipulation of the flow of photons in nanoengineered materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced broadband photonic and plasmonic technologies for spectrally tailorable integrated biosensing, nanostructured thin film solarcells, white light emitting diodes, novel plasmonic ensembles etc. Through a generic deterministic nanotechnological route here we show subwavelength-scale silicon (Si) nanostructures on nanoimprinted glass substrate in large area (4 cm2) with advanced functional features of aperiodic composite nanophotonic lattices. These nanophotonic aperiodic lattices have easily tailorable supercell tiles with well-defined and discrete lattice basis elements and they show rich Fourier spectra. The presented nanophotonic lattices are designed functionally akin to two-dimensional aperiodic composite lattices with unconventional flexibility- comprising periodic photonic crystals and/or in-plane photonic quasicrystals as pattern design subsystems. The fabricated composite lattice-structured Si nanostructures are comparatively analyzed with a range of nanophotonic structures with conventional lattice geometries of periodic, disordered random as well as in-plane quasicrystalline photonic lattices with comparable lattice parameters. As a proof of concept of compatibility with advanced bottom-up liquid phase crystallized (LPC) Si thin film fabrication, the experimental structural analysis is further extended to double-side-textured deterministic aperiodic lattice-structured 10 μm thick large area LPC Si film on nanoimprinted substrates.

  1. Development of a Large-Area Ultracold Neutron Detector

    NASA Astrophysics Data System (ADS)

    Stoffel, Jenna; Liu, Chen-Yu; UCN Tau Collaboration

    2015-10-01

    To improve our knowledge in particle physics and cosmology, including big-bang nucleosynthesis, we need a more precise and accurate measurement of the lifetime of free neutrons. Though there have been many attempts to measure the neutron lifetime, discrepancies exist between the two major experimental techniques of the beam and the bottle methods. To resolve this discrepancy, the UCN τ experiment will trap ultracold neutrons (UCNs) to perform lifetime measurements to the 1-second level. To accomplish this goal, we are developing a large-area, high-efficiency UCN detector. We construct a scintillating UCN detector by evaporating a thin film of boron-10 onto an airbrushed layer of zinc sulfide (ZnS); the 10B-coated ZnS scintillating film is then glued to wavelength-shifting plastic, which acts as a light guide to direct photons into modern silicon photomultipliers. This new detector has similar efficiency and background noise as the previously-used ion gas detectors, but can be easily scaled up to cover large areas for many applications. The new detector opens up exciting new ways to study systematic effects, as they hold the key to the interpretation of neutron lifetime.

  2. Deterministic composite nanophotonic lattices in large area for broadband applications.

    PubMed

    Xavier, Jolly; Probst, Jürgen; Becker, Christiane

    2016-12-12

    Exotic manipulation of the flow of photons in nanoengineered materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced broadband photonic and plasmonic technologies for spectrally tailorable integrated biosensing, nanostructured thin film solarcells, white light emitting diodes, novel plasmonic ensembles etc. Through a generic deterministic nanotechnological route here we show subwavelength-scale silicon (Si) nanostructures on nanoimprinted glass substrate in large area (4 cm(2)) with advanced functional features of aperiodic composite nanophotonic lattices. These nanophotonic aperiodic lattices have easily tailorable supercell tiles with well-defined and discrete lattice basis elements and they show rich Fourier spectra. The presented nanophotonic lattices are designed functionally akin to two-dimensional aperiodic composite lattices with unconventional flexibility- comprising periodic photonic crystals and/or in-plane photonic quasicrystals as pattern design subsystems. The fabricated composite lattice-structured Si nanostructures are comparatively analyzed with a range of nanophotonic structures with conventional lattice geometries of periodic, disordered random as well as in-plane quasicrystalline photonic lattices with comparable lattice parameters. As a proof of concept of compatibility with advanced bottom-up liquid phase crystallized (LPC) Si thin film fabrication, the experimental structural analysis is further extended to double-side-textured deterministic aperiodic lattice-structured 10 μm thick large area LPC Si film on nanoimprinted substrates.

  3. Geometric correction methods for Timepix based large area detectors

    NASA Astrophysics Data System (ADS)

    Zemlicka, J.; Dudak, J.; Karch, J.; Krejci, F.

    2017-01-01

    X-ray micro radiography with the hybrid pixel detectors provides versatile tool for the object inspection in various fields of science. It has proven itself especially suitable for the samples with low intrinsic attenuation contrast (e.g. soft tissue in biology, plastics in material sciences, thin paint layers in cultural heritage, etc.). The limited size of single Medipix type detector (1.96 cm2) was recently overcome by the construction of large area detectors WidePIX assembled of Timepix chips equipped with edgeless silicon sensors. The largest already built device consists of 100 chips and provides fully sensitive area of 14.3 × 14.3 cm2 without any physical gaps between sensors. The pixel resolution of this device is 2560 × 2560 pixels (6.5 Mpix). The unique modular detector layout requires special processing of acquired data to avoid occurring image distortions. It is necessary to use several geometric compensations after standard corrections methods typical for this type of pixel detectors (i.e. flat-field, beam hardening correction). The proposed geometric compensations cover both concept features and particular detector assembly misalignment of individual chip rows of large area detectors based on Timepix assemblies. The former deals with larger border pixels in individual edgeless sensors and their behaviour while the latter grapple with shifts, tilts and steps between detector rows. The real position of all pixels is defined in Cartesian coordinate system and together with non-binary reliability mask it is used for the final image interpolation. The results of geometric corrections for test wire phantoms and paleo botanic material are presented in this article.

  4. Ultra-stiff large-area carpets of carbon nanotubes.

    PubMed

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G; Murdock, Adrian T; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-09

    Herewith, we report the influence of post-synthesis heat treatment (≤2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm(2)) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, ≥4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.

  5. SPLASH The Southern Parkes Large-Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Walsh, Andrew; Dawson, Joanne

    2013-07-01

    The OH lines at 1612, 1665, 1667 and 1720 MHz are versatile probes of diffuse molecular gas, and may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a large, unbiassed and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane and Galactic Centre, that will achieve sensitivities an order of magnitude better than previous surveys. The project will answer critical questions on the global distribution of diffuse OH, the degree to which it traces 'hidden' emission caught between the regimes probed by traditional tracers, and its role as a probe of molecular cloud formation. As a blind and sensitive survey of all four ground-state transitions, SPLASH is also detecting many new OH masers, facilitating a broad range of astrophysical studies. I will report on the science aims and strategy of the survey, and present initial results from its first two semesters, which have revealed a rich and complex distribution of OH emission and absorption in a subsection of the Southern Milky Way.

  6. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Jones, Courtney; Krishnan, Vasaant

    2013-10-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 670 hours spread over two semesters to complete Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. Following the ongoing success of the project, we request that its pre-graded status be renewed for a final two semesters.

  7. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Gibson, Steven; Jones, Courtney; Krishnan, Vasaant

    2012-10-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ emission caught between the regimes probed by traditional tracers, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers as well as providing full Stokes information for all objects, facilitating a broad range of astrophysical studies. This proposal requests 1520 hours spread over three semesters to complete Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. Following the success of first observations last semester, we request that the project be granted pre-graded status.

  8. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Jones, Courtney; Krishnan, Vasaant

    2013-04-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ emission caught between the regimes probed by traditional tracers, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers as well as providing full Stokes information for all objects, facilitating a broad range of astrophysical studies. This proposal requests 1105 hours spread over two semesters to complete Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. Following the success of initial observations in 2012APRS, the project has been granted pre-graded status.

  9. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Breen, Shari; Hennebelle, Patrick; Gibson, Steven; Jones, Courtney

    2012-04-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. This proposal requests 1800 hours spread over four semesters to carry out Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ emission caught between the regimes probed by traditional tracers, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers as well as providing full Stokes information for all objects, facilitating a broad range of astrophysical studies.

  10. Improvement of accelerator of negative ion source on the Large Helical Device

    SciTech Connect

    Kisaki, M. Ikeda, K.; Osakabe, M.; Tsumori, K.; Nakano, H.; Nagaoka, K.; Kaneko, O.; Takeiri, Y.; Geng, S.

    2016-02-15

    To improve the performance of negative-ion based neutral beam injection on the Large Helical Device, the accelerator was modified on the basis of numerical investigations. A field limiting ring was installed on the upper side of a grounded grid (GG) support and a multi-slot GG was adopted instead of a multi-aperture GG. As a result, the voltage holding capability is improved and the heat load on the GG decreases by 40%. In addition, the arc efficiency is improved significantly only by replacing the GG.

  11. Large negative numbers in number theory, thermodynamics, information theory, and human thermodynamics

    NASA Astrophysics Data System (ADS)

    Maslov, V. P.

    2016-10-01

    We show how the abstract analytic number theory of Maier, Postnikov, and others can be extended to include negative numbers and apply this to thermodynamics, information theory, and human thermodynamics. In particular, we introduce a certain large number N 0 on the "zero level" with a high multiplicity number q i ≫ 1 related to the physical concept of gap in the spectrum. We introduce a general notion of "hole," similar to the Dirac hole in physics, in the theory. We also consider analogs of thermodynamical notions in human thermodynamics, in particular, in connection with the role of the individual in history.

  12. Large magnetostriction and negative thermal expansion in the frustrated antiferromagnet ZnCr2Se4.

    PubMed

    Hemberger, J; von Nidda, H-A Krug; Tsurkan, V; Loidl, A

    2007-04-06

    A detailed investigation of ZnCr2Se4 is presented which is dominated by strong ferromagnetic exchange but orders antiferromagnetically at TN=21 K. Specific heat and thermal expansion exhibit sharp first-order anomalies at the antiferromagnetic transition. TN is shifted to lower temperatures by external magnetic fields and finally is fully suppressed by a field of 65 kOe. The relative length change DeltaL/L(T) is unusually large and exhibits negative thermal expansion alpha below 75 K down to TN indicating strong frustration of the lattice. Magnetostriction DeltaL/L(H) reveals large values comparable to giant magnetostrictive materials. These results point to a spin-driven origin of the structural instability at TN explained in terms of competing ferromagnetic and antiferromagnetic exchange interactions.

  13. Large Barkhausen discontinuities in Co-based amorphous wires with negative magnetostriction

    SciTech Connect

    Yamasaki, J.; Humphrey, F.B.; Mohri, K.; Kawamura, H.; Takamure, H.; Maelmhaell, R.

    1988-04-15

    Magnetic properties, such as domain patterns and anisotropy, were measured for negative magnetostrictive Co-Si-B amorphous wires exhibiting large Barkhausen discontinuities and the results are compared to those of Fe-Si-B wires with positive magnetostriction. The Co-based wire was found to have a bamboolike domain structure at the wire surface. It was also shown that the amorphous wires prepared by the in-water quenching technique store tensile stress in the radial direction. The magnetostrictive anisotropy due to residual stress will produce an axial component of magnetization in conjunction with the two-dimensional geometry of wires making both Co- and Fe-based wires exhibit large Barkhausen discontinuities along the axis of the wire.

  14. Traveling-Wave Patterns in Binary Fluid Convection at Large Negative Separation Ratios.

    NASA Astrophysics Data System (ADS)

    Sokolov, R.; Aegerter, C. M.; Surko, C. M.

    2001-03-01

    In binary fluid mixtures, the coupling between the temperature and concentration fields leads to a regime of traveling-wave convection that does not exist in convection in pure fluids. (R. Walden, et al., PRL 55, 496 (1985)) The control parameter determining the traveling-wave nature of the convection is the separation ratio, Ψ, which relates the concentration flux to the temperature gradient. Recently, the existence of two stable TW states was predicted at large negative Ψ.(St. Hollinger, et al., PRL 78, 2 (1997)) We report on new experiments in ethanol-water mixtures for |Ψ|>0.6 in a large aspect ratio convection cell. The dynamics of the TW patterns will be analysed and compared to previous experiments at smaller values of |Ψ|. The experimentally measured bifurcation diagram will be presented, and the coexistence of domains of the two different TW states will be discussed.

  15. Negative ion production and beam extraction processes in a large ion source (invited)

    SciTech Connect

    Tsumori, K. Nakano, H.; Goto, M.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Ikeda, K.; Kisaki, M.; Geng, S.; Wada, M.; Sasaki, K.; Nishiyama, S.; Serianni, G.; Agostinetti, P.; Sartori, E.; Brombin, M.; Veltri, P.; Wimmer, C.

    2016-02-15

    Recent research results on negative-ion-rich plasmas in a large negative ion source have been reviewed. Spatial density and flow distributions of negative hydrogen ions (H{sup −}) and positive hydrogen ions together with those of electrons are investigated with a 4-pin probe and a photodetachment (PD) signal of a Langmuir probe. The PD signal is converted to local H{sup −} density from signal calibration to a scanning cavity ring down PD measurement. Introduction of Cs changes the slope of plasma potential local distribution depending upon the plasma grid bias. A higher electron density H{sub 2} plasma locally shields the bias potential and behaves like a metallic free electron gas. On the other hand, the bias and extraction electric fields penetrate in a Cs-seeded electronegative plasma even when the electron density is similar. Electrons are transported by the penetrated electric fields from the driver region along and across the filter and electron deflection magnetic fields. Plasma ions exhibited a completely different response against the penetration of electric fields.

  16. Primary gastric anaplastic lymphoma kinase-negative anaplastic large-cell lymphoma

    PubMed Central

    Tian, Chen; Zhang, Yizhuo

    2016-01-01

    Introduction Most primary stomach lymphomas are now recognized to originate from B-cell. Primary gastric anaplastic lymphoma kinase (ALK)-negative anaplastic large-cell lymphoma (ALCL) as shown in this case is very rare. Case report A 59-year-old man presented with a 1-month history of epigastric pain. Computed tomography showed a tumor in the stomach with perigastric lymphadenopathy. Biopsy of the tumor with gastroendoscopy showed ALCL. Bone marrow aspiration and trephine biopsy showed no infiltration. A diagnosis of primary gastric ALK-negative ALCL was made. The patient was first treated with four cycles of cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) regimen, but his condition did not show improvement. Then he was treated with two cycles of hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone/methotrexate and cytarabine (Hyper-CVAD/MA) regimen. In spite of these treatments, he still died of disease progression. Conclusion The prognosis of ALK-negative ALCLs is usually worse than ALK-positive ALCLs. In this case, the patient was not responsive to a multidrug chemotherapy with CHOP and Hyper-CVAD/MA. PMID:27695344

  17. Silicone implant and primary breast ALK1-negative anaplastic large cell lymphoma, fact or fiction?

    PubMed Central

    Li, Shiyong; Lee, Andrew K

    2010-01-01

    The safety of silicone-based implant for mammoplasty has been debated for decades. A series of anecdotal case reports and a recent epidemiological case-control study have suggested a possible association between silicone implant and the development of primary breast ALK1-negative anaplastic large cell lymphoma (ALCL), a rare type of peripheral T-cell lymphoma. In this report, we describe an additional case of primary breast ALK1-negative ALCL in the fibrous capsule and cystic fluid of silicone breast implant in a 58 year old woman who underwent breast reconstructive surgery after lumpectomy for her infiltrating breast adenocarcinoma. Morphologically and immunohistochemically, the lymphoma cells may be confused with recurrent infiltrating breast adenocarcinoma or other non-hematolymphoid malignancies. Molecular studies were needed to determine T-lineage differentiation of the malignant lymphoma cells. We will also review the case reports and case series published in the English literature and discuss our current understanding of silicone implant in primary breast ALK1-negative ALCL. PMID:19918336

  18. Searches for Axionlike Particles with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Albert, Andrea; Meyer, Manuel; Sanchez-Conde, Miguel; Wood, Matthew; LAT Collaboration

    2017-01-01

    Axionlike particles (ALPs) are dark-matter candidates that occur in a variety of extensions of the Standard Model. These particles could leave signatures in gamma rays, due to the coupling of ALPs to photons in external electromagnetic fields. To date, observations with Fermi Large Area Telescope (LAT) provide the strongest constraints on the photon-ALP coupling for ALP masses between 0.5 and 20 neV. Here, we summarize these constraints and present the sensitivity to detect an ALP induced gamma-ray burst from a Galactic core-collapse supernova. ALPs would be produced in the stellar medium via the Primakoff effect and convert into gamma rays in the Galactic magnetic field. Fermi LAT observations would be able to probe couplings where ALPs could constitute the entirety of dark matter. Below 1 neV, the Fermi-LAT sensitivity would surpass that of future laboratory experiments by one order of magnitude.

  19. Large area nuclear particle detectors using ET materials, phase 2

    NASA Technical Reports Server (NTRS)

    Wrigley, Charles Y.; Storti, George M.; Walter, Lee; Mathews, Scott

    1990-01-01

    This report presents work done under a Phase 2 SBIR contract for demonstrating large area detector planes utilizing Quantex electron trapping materials as a film medium for storing high-energy nuclide impingement information. The detector planes utilize energy dissipated by passage of the high-energy nuclides to produce localized populations of electrons stored in traps. Readout of the localized trapped electron populations is effected by scanning the ET plane with near-infrared, which frees the trapped electrons and results in optical emission at visible wavelengths. The effort involved both optimizing fabrication technology for the detector planes and developing a readout system capable of high spatial resolution for displaying the recorded nuclide passage tracks.

  20. Large-area multilayer infrared nano-wire grid polarizers

    NASA Astrophysics Data System (ADS)

    Gayduk, Alexey E.; Prinz, Victor Ya.; Seleznev, Vladimir A.; Rechkunov, Sergey N.

    2016-03-01

    We have developed a technology for fabricating infrared polarizers based on double- and four-layer metal-dielectric nanogratings. Due to the use of nanoimprint lithography, the size of fabricated samples with 190-nm grating period could be made exceeding 170 cm2. The fabricated polarizers are flexible, and they have high quality over the entire area of the sample. Spectrophotometric measurements and numerical simulations have showed that the polarizers exhibited a large transmission coefficient and a high extinction ratio (over 3 ṡ 104). In order to expand applications of polarizers to the bio-inspired wide field-of-view systems, technology for fabricating polarizers on curved surfaces prepared by 3D printing has been developed. The obtained results offer much promise for polarimetry purposes.

  1. Large Area Printing of 3D Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Watkins, James J.; Beaulieu, Michael R.; Hendricks, Nicholas R.; Kothari, Rohit

    2014-03-01

    We have developed a readily scalable print, lift, and stack approach for producing large area, 3D photonic crystal (PC) structures. UV-assisted nanoimprint lithography (UV-NIL) was used to pattern grating structures comprised of highly filled nanoparticle polymer composite resists with tune-able refractive indices (RI). The gratings were robust and upon release from a support substrate were oriented and stacked to yield 3D PCs. The RI of the composite resists was tuned between 1.58 and 1.92 at 800 nm while maintaining excellent optical transparency. The grating structure dimensions, line width, depth, and pitch, were easily varied by simply changing the imprint mold. For example, a 6 layer log-pile stack was prepared using a composite resist a RI of 1.72 yielding 72 % reflection at 900 nm. The process is scalable for roll-to-roll (R2R) production. Center for Hierarchical Manufacturing - an NSF Nanoscale Science and Engineering Center.

  2. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  3. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  4. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  5. The Second Fermi Large Area Telescope GRB Catalog

    NASA Astrophysics Data System (ADS)

    Kocevski, Daniel; Fermi Large Area Telescope Collaboration

    2017-01-01

    The high-energy emission from gamma-ray bursts (GRBs) is a formidable probe of extreme physics, requiring rapid variability from highly relativistic sources. Despite the advancements in our understanding of GRBs through observations by NASA's Swift and Fermi spacecraft, many fundemental questions regarding the particle acceleration and radiative processes associated with these events remain unanswered. Here we present the most extensive search for emission from GRBs above 40 MeV performed by the Fermi Large Area Telescope (LAT). The resulting catalog includes more than 130 detections and represents an improvement in the detection efficency of GRBs at high-energies of over 50% compared to the first LAT GRB catalog. We utilize this improved sensativity to characterize the high-energy emission from GRBs and review how these observations further our understanding of the nature of these events.

  6. Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device

    SciTech Connect

    Agostinetti, P.; Antoni, V.; Chitarin, G.; Pilan, N.; Serianni, G.; Veltri, P.; Cavenago, M.; Nakano, H.; Takeiri, Y.; Tsumori, K.

    2011-09-26

    At the National Institute for Fusion Science (NIFS) large-scaled negative ion sources have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device (LHD), which is the world-largest superconducting helical system. These injectors have achieved outstanding performances in terms of beam energy, negative-ion current and optics, and represent a reference for the development of heating and current drive NBIs for ITER.In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral Beam system (MITICA) is under construction at Consorzio RFX in Padova.An experimental validation of the codes has been undertaken in order to prove the accuracy of the simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS, with the goal of comparing and benchmarking the codes with the experimental data. A description of these modeling activities and a discussion of the main results obtained are reported in this paper.

  7. Large negative linear compressibility of Ag3[Co(CN)6

    PubMed Central

    Goodwin, Andrew L.; Keen, David A.; Tucker, Matthew G.

    2008-01-01

    Silver(I) hexacyanocobaltate(III), Ag3[Co(CN)6], shows a large negative linear compressibility (NLC, linear expansion under hydrostatic pressure) at ambient temperature at all pressures up to our experimental limit of 7.65(2) GPa. This behavior is qualitatively unaffected by a transition at 0.19 GPa to a new phase Ag3[Co(CN)6]-II, whose structure is reported here. The high-pressure phase also shows anisotropic thermal expansion with large uniaxial negative thermal expansion (NTE, expansion on cooling). In both phases, the NLC/NTE effect arises as the rapid compression/contraction of layers of silver atoms—weakly bound via argentophilic interactions—is translated via flexing of the covalent network lattice into an expansion along a perpendicular direction. It is proposed that framework materials that contract along a specific direction on heating while expanding macroscopically will, in general, also expand along the same direction under hydrostatic pressure while contracting macroscopically. PMID:19028875

  8. Background simulations for the Large Area Detector onboard LOFT

    NASA Astrophysics Data System (ADS)

    Campana, Riccardo; Feroci, Marco; Del Monte, Ettore; Mineo, Teresa; Lund, Niels; Fraser, George W.

    2013-12-01

    The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ˜10 m2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2‒30 keV, achieving about 5 mCrab in the most important 2-10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal.

  9. Towards large and powerful radio frequency driven negative ion sources for fusion

    NASA Astrophysics Data System (ADS)

    Heinemann, B.; Fantz, U.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.; Bonomo, F.; Fröschle, M.; Nocentini, R.; Riedl, R.

    2017-01-01

    The ITER neutral beam system will be equipped with radio-frequency (RF) negative ion sources, based on the IPP Garching prototype source design. Up to 100 kW at 1 MHz is coupled to the RF driver, out of which the plasma expands into the main source chamber. Compared to arc driven sources, RF sources are maintenance free and without evaporation of tungsten. The modularity of the driver concept permits to supply large source volumes. The prototype source (one driver) demonstrated operation in hydrogen and deuterium up to one hour with ITER relevant parameters. The ELISE test facility is operating with a source of half the ITER size (four drivers) in order to validate the modular source concept and to gain early operational experience at ITER relevant dimensions. A large variety of diagnostics allows improving the understanding of the relevant physics and its link to the source performance. Most of the negative ions are produced on a caesiated surface by conversion of hydrogen atoms. Cs conditioning and distribution have been optimized in order to achieve high ion currents which are stable in time. A magnetic filter field is needed to reduce the electron temperature and co-extracted electron current. The influence of different field topologies and strengths on the source performance, plasma and beam properties is being investigated. The results achieved in short pulse operation are close to or even exceed the ITER requirements with respect to the extracted ion currents. However, the extracted negative ion current for long pulse operation (up to 1 h) is limited by the increase of the co-extracted electron current, especially in deuterium operation.

  10. Development of a large area space solar cell assembly

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.

    1982-01-01

    The development of a large area high efficiency solar cell assembly is described. The assembly consists of an ion implanted silicon solar cell and glass cover. The important attributes of fabrication are the use of a back surface field which is compatible with a back surface reflector, and integration of coverglass application and cell fabrications. Cell development experiments concerned optimization of ion implantation processing of 2 ohm-cm boron-doped silicon. Process parameters were selected based on these experiments and cells with area of 34.3 sq cm wre fabricated. The average AMO efficiency of the twenty-five best cells was 13.9% and the best bell had an efficiency of 14.4%. An important innovation in cell encapsulation was also developed. In this technique, the coverglass is applied before the cell is sawed to final size. The coverglass and cell are then sawed as a unit. In this way, the cost of the coverglass is reduced, since the tolerance on glass size is relaxed, and costly coverglass/cell alignment procedures are eliminated. Adhesive investigated were EVA, FEP-Teflon sheet and DC 93-500. Details of processing and results are reported.

  11. Development of a large area space solar cell assembly

    NASA Astrophysics Data System (ADS)

    Spitzer, M. B.

    1982-05-01

    The development of a large area high efficiency solar cell assembly is described. The assembly consists of an ion implanted silicon solar cell and glass cover. The important attributes of fabrication are the use of a back surface field which is compatible with a back surface reflector, and integration of coverglass application and cell fabrications. Cell development experiments concerned optimization of ion implantation processing of 2 ohm-cm boron-doped silicon. Process parameters were selected based on these experiments and cells with area of 34.3 sq cm wre fabricated. The average AMO efficiency of the twenty-five best cells was 13.9% and the best bell had an efficiency of 14.4%. An important innovation in cell encapsulation was also developed. In this technique, the coverglass is applied before the cell is sawed to final size. The coverglass and cell are then sawed as a unit. In this way, the cost of the coverglass is reduced, since the tolerance on glass size is relaxed, and costly coverglass/cell alignment procedures are eliminated. Adhesive investigated were EVA, FEP-Teflon sheet and DC 93-500. Details of processing and results are reported.

  12. A large area detector for x-ray applications

    SciTech Connect

    Rodricks, B.; Huang, Qiang; Hopf, R.; Wang, Kemei

    1993-10-01

    A large area detector for x-ray synchrotron applications has been developed. The front end of this device consist of a scintillator coupled to a fiber-optic taper. The fiber-optic taper is comprised of 4 smaller (70 mm x 70 mm) tapers fused together in a square matrix giving an active area of 140 mm x 140 mm. Each taper has a demagnification of 5.5 resulting in four small ends that are 12 mm diagonally across. The small ends of each taper are coupled to four microchannel-plate-based image intensifiers. The output from each image intensifier is focused onto a Charge Coupled Device (CCD) detector. The four CCDs are read out in parallel and are independently controlled. The image intensifiers also act as fast (20 ns) electronic shutters. The system is capable of displaying images in real time. Additionally, with independent control on the readout of each row of data from the CCD, the system is capable of performing high speed imaging through novel readout manipulation.

  13. Large area patterning using interference and nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Bläsi, B.; Tucher, N.; Höhn, O.; Kübler, V.; Kroyer, T.; Wellens, Ch.; Hauser, H.

    2016-04-01

    Interference lithography (IL) is the best suited technology for the origination of large area master structures with high resolution. In prior works, we seamlessly pattern areas of up to 1.2 x 1.2 m2 with periodic features, i.e. a diffraction grating with a period in the micron range. For this process we use an argon ion laser emitting at 363.8 nm. Thus, feasible periods are in the range of 100 μm to 200 nm. Edge-defined techniques or also called (self-aligned) double patterning processes can be used to double the spatial frequency of such structures. This way, we aim to reduce achievable periods further down to 100 nm. In order to replicate master structures, we make use of nanoimprint lithography (NIL) processes. In this work, we present results using IL as mastering and NIL as replication technology in the fields of photovoltaics as well as display and lighting applications. In photovoltaics different concepts like the micron-scale patterning of the front side as well as the realization of rear side diffraction gratings are presented. The benefit for each is shown on final device level. In the context of display and lighting applications, we realized various structures ranging from designed, symmetric or asymmetric, diffusers, antireflective and/or antiglare structures, polarization optical elements (wire grid polarizers), light guidance and light outcoupling structures.

  14. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.

    2016-01-01

    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  15. Fermi Large Area Telescope as a Galactic Supernovae Axionscope.

    PubMed

    Meyer, M; Giannotti, M; Mirizzi, A; Conrad, J; Sánchez-Conde, M A

    2017-01-06

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to g_{aγ}≃2×10^{-13}  GeV^{-1} for an ALP mass m_{a}≲10^{-9}  eV. These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. If no γ-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.

  16. Second generation large area microchannel plate flat panel phototubes

    NASA Astrophysics Data System (ADS)

    Ertley, C. D.; Siegmund, O. H. W.; Jelinsky, S. R.; Tedesco, J.; Minot, M. J.; O'Mahony, A.; Craven, C. A.; Popecki, M.; Lyashenko, A. V.; Foley, M. R.

    2016-07-01

    Very large (20 cm × 20 cm) flat panel phototubes are being developed which employ novel microchannel plates (MCPs). The MCPs are manufactured using borosilicate microcapillary arrays which are functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD). This allows the operational parameters to be set by tailoring sequential ALD deposition processes. The borosilicate substrates are robust, including the ability to be produced in large formats (20 cm square). ALD MCPs have performance characteristics (gain, pulse amplitude distributions, and imaging) that are equivalent or better than conventional MCPs. They have low intrinsic background (0.045 events cm-2 sec-1)., high open area ratios (74% for the latest generation of borosilicate substrates), and stable gain during >7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). The tube assemblies use a pair of 20 cm × 20 cm ALD MCPs comprised of a borosilicate entrance window, a proximity focused bialkali photocathode, and a strip-line readout anode. The second generation design employs an all glass body with a hot indium seal and a transfer photocathode. We have achieved >20% quantum efficiency and good gain uniformity over the 400 cm2 field of view, spatial resolution of <1 cm and obtained event timing accuracy of close to 100 ps FWHM.

  17. The Gamma-Ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Ritz, Steve

    2008-01-01

    The Gamma-ray Large Area Space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view will make it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its upcoming launch, GLAST will open a new and important window on a wide variety of high-energy phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for signals of hypothetical new phenomena such as supersymmetric dark matter annihilations. In addition to the science opportunities, this talk includes a brief description of the instruments, the opportunities for guest investigators, and the mission status.

  18. The Gamma-ray Large Area Space Telescope (GLAST)

    NASA Technical Reports Server (NTRS)

    Ritz, Steve

    2008-01-01

    The Gamma-ray Large Area Space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view will make it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its upcoming launch, GLAST will open a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations and Lorentz invariance violation. In addition to the science opportunities, this talk includes a description of the instruments, the opportunities for guest investigators, and the mission status.

  19. Fermi Large Area Telescope as a Galactic Supernovae Axionscope

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Giannotti, M.; Mirizzi, A.; Conrad, J.; Sánchez-Conde, M. A.

    2017-01-01

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to ga γ≃2 ×10-13 GeV-1 for an ALP mass ma≲10-9 eV . These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. If no γ -ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.

  20. Ultra-stiff large-area carpets of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G.; Murdock, Adrian T.; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, >=4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under

  1. Large scale track analysis for wide area motion imagery surveillance

    NASA Astrophysics Data System (ADS)

    van Leeuwen, C. J.; van Huis, J. R.; Baan, J.

    2016-10-01

    Wide Area Motion Imagery (WAMI) enables image based surveillance of areas that can cover multiple square kilometers. Interpreting and analyzing information from such sources, becomes increasingly time consuming as more data is added from newly developed methods for information extraction. Captured from a moving Unmanned Aerial Vehicle (UAV), the high-resolution images allow detection and tracking of moving vehicles, but this is a highly challenging task. By using a chain of computer vision detectors and machine learning techniques, we are capable of producing high quality track information of more than 40 thousand vehicles per five minutes. When faced with such a vast number of vehicular tracks, it is useful for analysts to be able to quickly query information based on region of interest, color, maneuvers or other high-level types of information, to gain insight and find relevant activities in the flood of information. In this paper we propose a set of tools, combined in a graphical user interface, which allows data analysts to survey vehicles in a large observed area. In order to retrieve (parts of) images from the high-resolution data, we developed a multi-scale tile-based video file format that allows to quickly obtain only a part, or a sub-sampling of the original high resolution image. By storing tiles of a still image according to a predefined order, we can quickly retrieve a particular region of the image at any relevant scale, by skipping to the correct frames and reconstructing the image. Location based queries allow a user to select tracks around a particular region of interest such as landmark, building or street. By using an integrated search engine, users can quickly select tracks that are in the vicinity of locations of interest. Another time-reducing method when searching for a particular vehicle, is to filter on color or color intensity. Automatic maneuver detection adds information to the tracks that can be used to find vehicles based on their

  2. Large-area rice yield forecasting using satellite imageries

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Ping; Chang, Kuo-Wei; Chen, Rong-Kuen; Lo, Jeng-Chung; Shen, Yuan

    2010-02-01

    Ability to make large-area yield prediction before harvest is important in many aspects of agricultural decision-making. In this study, canopy reflectance band ratios (NIR/RED, NIR/GRN) of paddy rice ( Oryza sativa L.) at booting stage, from field measurements conducted from 1999 to 2005, were correlated with the corresponding yield data to derive regression-type yield prediction models for the first and second season crop, respectively. These yield models were then validated with ground truth measurements conducted in 2007 and 2008 at eight sites, of different soil properties, climatic conditions, and various treatments in cultivars planted and N application rates, using surface reflectance retrieved from atmospherically corrected SPOT imageries. These validation tests indicated that root mean square error of predicting grain yields per unit area by the proposed models were less than 0.7 T ha -1 for both cropping seasons. Since village is the basic unit for national rice yield census statistics in Taiwan, the yield models were further used to forecast average regional yields for 14 selected villages and compared with officially reported data. Results indicate that the average yield per unit area at village scale can be forecasted with a root mean square error of 1.1 T ha -1 provided no damaging weather occurred during the final month before actual harvest. The methodology can be applied to other optical sensors with similar spectral bands in the visible/near-infrared and to different geographical regions provided that the relation between yield and spectral index is established.

  3. Methods for Finding Legacy Wells in Large Areas

    SciTech Connect

    Hammack, Richard W.; Veloski, Garret A.; Hodges, D. Greg; White, Jr., Curt M.

    2016-06-16

    United States. When abandoned, many wells were not adequately sealed and now provide a potential conduit for the vertical movement of liquids and gases. Today, groundwater aquifers can be contaminated by surface pollutants flowing down wells or by deep, saline water diffusing upwards. Likewise, natural gas, carbon dioxide (CO2), or radon can travel upwards via these wells to endanger structures or human health on the surface. Recently, the need to find and plug wells has become critical with the advent of carbon dioxide injection into geologic formations for enhanced oil recovery (EOR) or carbon storage. The potential for natural gas or brine leakage through existing wells has also been raised as a concern in regions where shale resources are hydraulically fractured for hydrocarbon recovery. In this study, the National Energy Technology Laboratory (NETL) updated existing, effective well finding techniques to be able to survey large areas quickly using helicopter or ground-vehicle-mounted magnetometers, combined with mobile methane detection. For this study, magnetic data were collected using airborne and ground vehicles equipped with two boom-mounted magnetometers, or on foot using a hand-held magnetometer with a single sensor. Data processing techniques were employed to accentuate well-casing-type magnetic signatures. To locate wells with no magnetic signature (wells where the steel well casing had been removed), the team monitored for anomalous concentrations of methane, which could indicate migration of volatile compounds from deeper sedimentary strata along a well or fracture pathway. Methane measurements were obtained using the ALPIS DIfferential Absorption Lidar (DIAL) sensor for helicopter surveys and the Apogee leak detection system (LDS) for ground surveys. These methods were evaluated at a 100-year-old oilfield in Wyoming, where a helicopter magnetic survey accurately located 93% of visible wells. In addition, 20% of the wells found by the survey were

  4. Llamas: Large-area microphone arrays and sensing systems

    NASA Astrophysics Data System (ADS)

    Sanz-Robinson, Josue

    Large-area electronics (LAE) provides a platform to build sensing systems, based on distributing large numbers of densely spaced sensors over a physically-expansive space. Due to their flexible, "wallpaper-like" form factor, these systems can be seamlessly deployed in everyday spaces. They go beyond just supplying sensor readings, but rather they aim to transform the wealth of data from these sensors into actionable inferences about our physical environment. This requires vertically integrated systems that span the entirety of the signal processing chain, including transducers and devices, circuits, and signal processing algorithms. To this end we develop hybrid LAE / CMOS systems, which exploit the complementary strengths of LAE, enabling spatially distributed sensors, and CMOS ICs, providing computational capacity for signal processing. To explore the development of hybrid sensing systems, based on vertical integration across the signal processing chain, we focus on two main drivers: (1) thin-film diodes, and (2) microphone arrays for blind source separation: 1) Thin-film diodes are a key building block for many applications, such as RFID tags or power transfer over non-contact inductive links, which require rectifiers for AC-to-DC conversion. We developed hybrid amorphous / nanocrystalline silicon diodes, which are fabricated at low temperatures (<200 °C) to be compatible with processing on plastic, and have high current densities (5 A/cm2 at 1 V) and high frequency operation (cutoff frequency of 110 MHz). 2) We designed a system for separating the voices of multiple simultaneous speakers, which can ultimately be fed to a voice-command recognition engine for controlling electronic systems. On a device level, we developed flexible PVDF microphones, which were used to create a large-area microphone array. On a circuit level we developed localized a-Si TFT amplifiers, and a custom CMOS IC, for system control, sensor readout and digitization. On a signal processing

  5. Building ISOC Status Displays for the Large AreaTelescope aboard the Gamma Ray Large Area Space Telescope (GLAST) Observatory

    SciTech Connect

    Ketchum, Christina; /SLAC

    2006-09-01

    In September 2007 the Gamma Ray Large Area Space Telescope (GLAST) is scheduled to launch aboard a Delta II rocket in order to put two high-energy gamma-ray detectors, the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM) into low earth orbit. The Instrument Science Operations Center (ISOC) at SLAC is responsible for the LAT operations for the duration of the mission, and will therefore build an operations center including a monitoring station at SLAC to inform operations staff and visitors of the status of the LAT instrument and GLAST. This monitoring station is to include sky maps showing the location of GLAST in its orbit as well as the LAT's projected field of view on the sky containing known gamma-ray sources. The display also requires a world map showing the locations of GLAST and three Tracking and Data Relay Satellites (TDRS) relative to the ground, their trail lines, and ''footprint'' circles indicating the range of communications for each satellite. The final display will also include a space view showing the orbiting and pointing information of GLAST and the TDRS satellites. In order to build the displays the astronomy programs Xephem, DS9, SatTrack, and STK were employed to model the position of GLAST and pointing information of the LAT instrument, and the programming utilities Python and Cron were used in Unix to obtain updated information from database and load them into the programs at regular intervals. Through these methods the indicated displays were created and combined to produce a monitoring display for the LAT and GLAST.

  6. Exceptionally large positive and negative anisotropic thermal expansion of an organic crystalline material

    NASA Astrophysics Data System (ADS)

    Das, Dinabandhu; Jacobs, Tia; Barbour, Leonard J.

    2010-01-01

    In general, the relatively modest expansion experienced by most materials on heating is caused by increasing anharmonic vibrational amplitudes of the constituent atoms, ions or molecules. This phenomenon is called positive thermal expansion (PTE) and usually occurs along all three crystallographic axes. In very rare cases, structural peculiarities may give rise either to anomalously large PTE, or to negative thermal expansion (NTE, when lattice dimensions shrink with heating). As NTE and unusually large PTE are extremely uncommon for molecular solids, mechanisms that might give rise to such phenomena are poorly understood. Here we show that the packing arrangement of a simple dumbbell-shaped organic molecule, coupled with its intermolecular interactions, facilitates a cooperative mechanical response of the three-dimensional framework to changes in temperature. A series of detailed structural determinations at 15-K intervals has allowed us to visualize the process at the molecular level. The underlying mechanism is reminiscent of a three-dimensional (3D) folding trellis and results in exceptionally large and reversible uniaxial PTE and biaxial NTE of the crystal. Understanding such mechanisms is highly desirable for the future design of sensitive thermomechanical actuators.

  7. Large area mode field photonic crystal fiber design

    NASA Astrophysics Data System (ADS)

    Guo, Shuqin; An, Wensheng; Wang, Kang; Zhu, Guangxin; Le, Zichun

    2005-11-01

    A novel design method about photonic crystal fiber (PCF) with large area model field (LAMF) is demonstrated. Different from ordinarily design that the core of PCF formed by missing one air holes in the center of section, many air holes distributed in heartland all together come into being the core region. Air holes are arranged regularly in core region and outer cladding regions according to different periodical character, respectively. The effective refractive index (n eff ) of core region should be higher than cladding region because of total internal reflection (TIR) requirement. In this paper, two kinds of typical scheme are offered to realize LAMF-PCF. First, Λ, the spacing of neighboring air holes in whole section is fixed, once the radius of air holes in the core region r c is smaller than the cladding air holes r cla, LAMF-PCF will be formed. The modal area only lessens a little as r c is reduced. Especially, optimal size of r c can nearly make MFA insensitive to wavelength. On the contrary, dispersion parameter of PCF will take place visible change along with r c reduced, and ultra-flattened dispersion character can be realized when r c is optimized. Another method of designing LAMF-PCF is keeping all air holes uniform in the whole section of PCF, but the space of neighboring air holes in the core region Λ c is longer than the cladding region Λ cla, so n eff of core region is higher than the cladding region and TIR can take place.

  8. Large-area monolayer hexagonal boron nitride on Pt foil.

    PubMed

    Park, Ji-Hoon; Park, Jin Cheol; Yun, Seok Joon; Kim, Hyun; Luong, Dinh Hoa; Kim, Soo Min; Choi, Soo Ho; Yang, Woochul; Kong, Jing; Kim, Ki Kang; Lee, Young Hee

    2014-08-26

    Hexagonal boron nitride (h-BN) has recently been in the spotlight due to its numerous applications including its being an ideal substrate for two-dimensional electronics, a tunneling material for vertical tunneling devices, and a growth template for heterostructures. However, to obtain a large area of h-BN film while maintaining uniform thickness is still challenging and has not been realized. Here, we report the systematical study of h-BN growth on Pt foil by using low pressure chemical vapor deposition with a borazine source. The monolayer h-BN film was obtained over the whole Pt foil (2 × 5 cm(2)) under <100 mTorr, where the size is limited only by the Pt foil size. A borazine source was catalytically decomposed on the Pt surface, leading to the self-limiting growth of the monolayer without the associating precipitation, which is very similar to the growth of graphene on Cu. The orientation of the h-BN domains was largely confined by the Pt domain, which is confirmed by polarizing optical microscopy (POM) assisted by the nematic liquid crystal (LC) film. The total pressure and orientation of the Pt lattice plane are crucial parameters for thickness control. At high pressure (∼0.5 Torr), thick film was grown on Pt (111), and in contrast, thin film was grown on Pt (001). Our advances in monolayer h-BN growth will play an important role to further develop a high quality h-BN film that can be used for vertical tunneling, optoelectronic devices and growth templates for a variety of heterostructures.

  9. Simultaneous Non-Negative Matrix Factorization for Multiple Large Scale Gene Expression Datasets in Toxicology

    PubMed Central

    Lee, Clare M.; Mudaliar, Manikhandan A. V.; Haggart, D. R.; Wolf, C. Roland; Miele, Gino; Vass, J. Keith; Higham, Desmond J.; Crowther, Daniel

    2012-01-01

    Non-negative matrix factorization is a useful tool for reducing the dimension of large datasets. This work considers simultaneous non-negative matrix factorization of multiple sources of data. In particular, we perform the first study that involves more than two datasets. We discuss the algorithmic issues required to convert the approach into a practical computational tool and apply the technique to new gene expression data quantifying the molecular changes in four tissue types due to different dosages of an experimental panPPAR agonist in mouse. This study is of interest in toxicology because, whilst PPARs form potential therapeutic targets for diabetes, it is known that they can induce serious side-effects. Our results show that the practical simultaneous non-negative matrix factorization developed here can add value to the data analysis. In particular, we find that factorizing the data as a single object allows us to distinguish between the four tissue types, but does not correctly reproduce the known dosage level groups. Applying our new approach, which treats the four tissue types as providing distinct, but related, datasets, we find that the dosage level groups are respected. The new algorithm then provides separate gene list orderings that can be studied for each tissue type, and compared with the ordering arising from the single factorization. We find that many of our conclusions can be corroborated with known biological behaviour, and others offer new insights into the toxicological effects. Overall, the algorithm shows promise for early detection of toxicity in the drug discovery process. PMID:23272042

  10. Recent Progress in the Negative-Ion-Based Neutral Beam Injectors in Large Helical Device

    SciTech Connect

    Takeiri, Y.; Tsumori, K.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Oka, Y.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Kaneko, O.

    2009-03-12

    Negative-ion-based neutral beam injection (negative-NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to the improvement of the negative ion sources. Up to now, every injector achieves the designed injection energy and power of 180 keV-5 MW with hydrogen beams, and the total injection power exceeds 16 MW with three injectors. In the multi-round aperture grounded grid (GG), the diameter of a round aperture has been enlarged for higher GG transparency. Then, the GG heat load is reduced, as well as in the multi-slotted GG, and the voltage holding ability in the beam acceleration was improved. As a result, the beam energy is raised and the injection power is increased. To improve the anisotropic property of the beamlet convergence condition between the perpendicular and the parallel directions to the slots in the multi-slotted GG, a round-shape aperture of the steering grid (SG) has been changed to a racetrack shape. As a result, the difference of the beamlet conversion condition is much mitigated, and the injection efficiency (port-transmission efficiency) is improved, leading to 188 keV-6.4 MW injection. The Cs consumption is observed to be proportional to the tungsten evaporation from filaments. The Cs behavior is investigated with optical emission spectroscopy. During the beam extraction, the Cs recycling is dominated by Cs on the backplate, which is evaporated into the plasma by the backstreaming positive ions, and the wall surfaces should be loss regions for the supplied Cs.

  11. Recent Progress in the Negative-Ion-Based Neutral Beam Injectors in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Takeiri, Y.; Tsumori, K.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Oka, Y.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Kaneko, O.

    2009-03-01

    Negative-ion-based neutral beam injection (negative-NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to the improvement of the negative ion sources. Up to now, every injector achieves the designed injection energy and power of 180 keV-5 MW with hydrogen beams, and the total injection power exceeds 16 MW with three injectors. In the multi-round aperture grounded grid (GG), the diameter of a round aperture has been enlarged for higher GG transparency. Then, the GG heat load is reduced, as well as in the multi-slotted GG, and the voltage holding ability in the beam acceleration was improved. As a result, the beam energy is raised and the injection power is increased. To improve the anisotropic property of the beamlet convergence condition between the perpendicular and the parallel directions to the slots in the multi-slotted GG, a round-shape aperture of the steering grid (SG) has been changed to a racetrack shape. As a result, the difference of the beamlet conversion condition is much mitigated, and the injection efficiency (port-transmission efficiency) is improved, leading to 188 keV-6.4 MW injection. The Cs consumption is observed to be proportional to the tungsten evaporation from filaments. The Cs behavior is investigated with optical emission spectroscopy. During the beam extraction, the Cs recycling is dominated by Cs on the backplate, which is evaporated into the plasma by the backstreaming positive ions, and the wall surfaces should be loss regions for the supplied Cs.

  12. Large negative thermal expansion of a polymer driven by a submolecular conformational change

    NASA Astrophysics Data System (ADS)

    Shen, Xingyuan; Viney, Christopher; Johnson, Erin R.; Wang, Changchun; Lu, Jennifer Q.

    2013-12-01

    Mechanoresponsive polymers hold great technological potential in drug delivery, ‘smart’ optical systems and microelectromechanical systems. However, hysteresis and fatigue (associated with large-scale polymer chain rearrangement) are often problematic. Here, we describe a polyarylamide film that contains s-dibenzocyclooctadiene (DBCOD), which can generate unconventional and completely reversible thermal contraction under low-energy stimulation. The films exhibit a giant negative thermal expansion coefficient of approximately -1,200 ppm K-1 at ambient or near-ambient temperatures, much higher than any known negative-thermal-expansion materials under similar operating conditions. Mechanical characterization, calorimetry, spectroscopic analysis and density-functional theory calculations all point to the conformational change of the DBCOD moiety, from the thermodynamic global energy minimum (twist-boat) to a local minimum (chair), as the origin of this abnormal thermal shrinkage. This newly identified, low-energy-driven, thermally agile molecular subunit opens a new pathway to creating near-infrared-based macromolecular switches and motors, and for ambient thermal energy storage and conversion.

  13. Large negative thermal expansion of a polymer driven by a submolecular conformational change.

    PubMed

    Shen, Xingyuan; Viney, Christopher; Johnson, Erin R; Wang, Changchun; Lu, Jennifer Q

    2013-12-01

    Mechanoresponsive polymers hold great technological potential in drug delivery, 'smart' optical systems and microelectromechanical systems. However, hysteresis and fatigue (associated with large-scale polymer chain rearrangement) are often problematic. Here, we describe a polyarylamide film that contains s-dibenzocyclooctadiene (DBCOD), which can generate unconventional and completely reversible thermal contraction under low-energy stimulation. The films exhibit a giant negative thermal expansion coefficient of approximately -1,200 ppm K(-1) at ambient or near-ambient temperatures, much higher than any known negative-thermal-expansion materials under similar operating conditions. Mechanical characterization, calorimetry, spectroscopic analysis and density-functional theory calculations all point to the conformational change of the DBCOD moiety, from the thermodynamic global energy minimum (twist-boat) to a local minimum (chair), as the origin of this abnormal thermal shrinkage. This newly identified, low-energy-driven, thermally agile molecular subunit opens a new pathway to creating near-infrared-based macromolecular switches and motors, and for ambient thermal energy storage and conversion.

  14. Inclined layer convection in a colloidal suspension with negative Soret coefficient at large solutal Rayleigh numbers.

    PubMed

    Italia, Matteo; Croccolo, Fabrizio; Scheffold, Frank; Vailati, Alberto

    2014-10-01

    Convection in an inclined layer of fluid is affected by the presence of a component of the acceleration of gravity perpendicular to the density gradient that drives the convective motion. In this work we investigate the solutal convection of a colloidal suspension characterized by a negative Soret coefficient. Convection is induced by heating the suspension from above, and at large solutal Rayleigh numbers (of the order of 10(7)-10(8)) convective spoke patterns form. We show that in the presence of a marginal inclination of the cell as small as 19 mrad the isotropy of the spoke pattern is broken and the convective patterns tend to align in the direction of the inclination. At intermediate inclinations of the order of 33 mrad ordered square patterns are obtained, while at inclination of the order of 67 mrad the strong shear flow determined by the inclination gives rise to ascending and descending sheets of fluid aligned parallel to the direction of inclination.

  15. Large area CNT-Si heterojunction for photodetection

    NASA Astrophysics Data System (ADS)

    Aramo, C.; Ambrosio, M.; Bonavolontà, C.; Boscardin, M.; Crivellari, M.; de Lisio, C.; Grossi, V.; Maddalena, P.; Passacantando, M.; Valentino, M.

    2017-02-01

    Multiwall carbon nanotubes (MWCNTs) consist of multiple layers of graphite sheets arranged in concentric cylinders, from two to many tens. These systems are closely related to graphite layers but in some features, MWCNTs behave quite differently from graphite. In particular, their ability to generate a photocurrent in a wide wavelength range has been demonstrated either without or with the application of a draining voltage. In addition, the photocurrent signal has been found to reproduce the optical absorbance of MWCNTs, showing a maximum in the near UV region. In this paper main characteristics of a novel large area photodetector featuring low noise, high linearity and efficiency are reported. This detector has been obtained by coupling the optoelectronic characteristics of MWCNTs with the well-known properties of silicon. MWCNTs are growth on n-doped silicon layer by chemical vapour deposition creating a p-n heterojunction with high sensitivity to the radiation from UV to IR. An additional MIS junction is obtained with a metallic conductive layer deposited on the back of silicon substrate. Moreover, first results on the signals generated by pulsed laser are also reported.

  16. Removable Large-Area Ultrasmooth Silver Nanowire Transparent Composite Electrode.

    PubMed

    Jin, Yunxia; Wang, Kaiqing; Cheng, Yuanrong; Pei, Qibing; Xu, Yuxi; Xiao, Fei

    2017-02-08

    In this work, a composite silver nanowire (AgNW) transparent electrode that is large-area ultrasmooth without conductivity or transmittance scarifice, removable but with good resistance to both water and organic solvent, is reported. Via a simple low-temperature solution process without complicated transfer steps or additional pressure pressing, a new kind of AgNWs composite with biocompatible and patternable chitosan polymer complex demonstrates a quite low root-mean-square roughness ∼7 nm at a largest reported scan size of 50 μm × 50 μm, which is among the best flat surface. After long-term exposure to both water and organic solvent, it still shows strong adhesion, unchanged transparency, and no obvious conductivity reduction, suggesting a good stability staying on the substrate. Meanwhile, the polymer and silver nanowire in the composite electrode can be damaged via the same process through concentrated acid or base etching to leave off the substrate, allowing a simple patterning technology. Besides, the imported insulating polymer does not lower down the opto-electrical performance, and a high figure of merit close to 300 is obtained for the composite electrode, significantly outperforming the optoelectronic performance of indium-tin oxide (ITO) coated plastics (∼100) and comparable to ITO-coated glass. It shows great advantage to replace ITO as a promising transparent electrode.

  17. Saturn: A large area x-ray simulation accelerator

    SciTech Connect

    Bloomquist, D.D.; Stinnett, R.W.; McDaniel, D.H.; Lee, J.R.; Sharpe, A.W.; Halbleib, J.A.; Schlitt, L.G.; Spence, P.W.; Corcoran, P.

    1987-01-01

    Saturn is the result of a major metamorphosis of the Particle Beam Fusion Accelerator-I (PBFA-I) from an ICF research facility to the large-area x-ray source of the Simulation Technology Laboratory (STL) project. Renamed Saturn, for its unique multiple-ring diode design, the facility is designed to take advantage of the numerous advances in pulsed power technology made by the ICF program in recent years and much of the existing PBFA-I support system. Saturn will include significant upgrades in the energy storage and pulse-forming sections. The 36 magnetically insulated transmission lines (MITLs) that provided power flow to the ion diode of PBFA-I were replaced by a system of vertical triplate water transmission lines. These lines are connected to three horizontal triplate disks in a water convolute section. Power will flow through an insulator stack into radial MITLs that drive the three-ring diode. Saturn is designed to operate with a maximum of 750 kJ coupled to the three-ring e-beam diode with a peak power of 25 TW to provide an x-ray exposure capability of 5 x 10/sup 12/ rads/s (Si) and 5 cal/g (Au) over 500 cm/sup 2/.

  18. Influence of the Earth's magnetic field on large area photomultipliers

    SciTech Connect

    Leonora, E.; Aiello, S.; Leotta, G.

    2011-07-01

    The influence of the Earth's magnetic field on large area photomultipliers proposed for a future deep sea neutrino telescope was studied under the EU-funded KM3NeT design study. The aims were to evaluate variations in PMT performance in the Earth's magnetic field and to decide whether the use of magnetic shielding is necessary. Measurements were performed on three Hamamatsu PMTs: two 8-inch R5912 types, one of these with super-bi-alkali photocathode, and a 10-inch R7081 type with a standard bi-alkali photocathode. The various characteristics of the PMTs were measured while varying the PMT orientations with respect to the Earth's magnetic field, both with and without a mu-metal cage as magnetic shield. In the 8-inch PMTs the impact of the magnetic field was found to be smaller than that on the 10-inch PMT. The increased quantum efficiency in the 8 super-bi-alkali PMT almost compensated its smaller detection surface compared to the 10' PMT. No significant effects were measured upon transit time and the fraction of spurious pulses. (authors)

  19. Recent advances in very large area avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Squillante, Michael R.; Christian, James; Entine, Gerald; Farrell, Richard; Karger, Arieh M.; McClish, Mickel; Myers, Richard; Shah, Kanai S.; Taylor, David; Vanderpuye, Kofi; Waer, Peter; Woodring, Mitchell

    2003-09-01

    The Avalanche Photodiode (APD) is a unique device that combines the advantages of solid state photodetectors with those of high gain devices such as photomultiplier tubes (PMTs). APDs have internal gain that provides a high signal-to-noise ratio. APDs have high quantum efficiency, are fast, compact, and rugged. These properties make them suitable detectors for important applications such as LADAR, detection and identification toxic chemicals and bio-warfare agents, LIDAR fluorescence detection, stand-off laser induced breakdown spectroscopy (LIBS), and nuclear detectors and imagers. Recently there have been significant technical breakthroughs in fabricating very large APDs, APD arrays, and position sensitive APD arrays (PSAPD). Signal gain of over 10,000 has been achieved, single element APDs have been fabricated with active area greater than 40 cm2, monolithic pixelated arrays with up to 28 x 28 elements have been fabricated, and position sensitive APDs have been developed and tested. Additionally, significant progress has been made in improving the fabrication process to provide better uniformity and high yield, permitting cost effective manufacturing of APDs for reduced cost.

  20. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bisello, D.; Baughman, B. M. E-mail: massimiliano.razzano@pi.infn.it

    2009-05-10

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new {gamma}-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E {>=} 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of {gamma} = 1.51{sup +0.05} {sub -0.04} with an exponential cutoff at E{sub c} = 2.9 {+-} 0.1 GeV. Spectral fits with generalized cutoffs of the form e{sup -(E/E{sub c}){sup b}} require b {<=} 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.

  1. Large-area nanogap plasmon resonator arrays for plasmonics applications

    NASA Astrophysics Data System (ADS)

    Jin, Mingliang; van Wolferen, Henk; Wormeester, Herbert; van den Berg, Albert; Carlen, Edwin T.

    2012-07-01

    Large-area (~8000 mm2) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (~1 km cm-2), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a1), βCCC + νCS ring mode (1074 cm-1) of BT on surfaces with pitch λg = 200 nm, AEF = 0.8 × 106 and for surfaces with λg = 500 nm, AEF = 0.3 × 107 from over 99% of the imaged spots. Maximum AEFs > 108 have been measured in both cases.

  2. Fermi Large Area Telescope Operations: Progress Over 4 Years

    SciTech Connect

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  3. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  4. Fabrication of large area nanostructures with surface modified silica spheres

    NASA Astrophysics Data System (ADS)

    Kang, Kwang-Sun

    2014-03-01

    Surface modification of silica spheres with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) has been performed at ambient condition. However, the FTIR spectra and field emission scanning electron microscope (FESEM) images show no evidence of the surface modification. The reaction temperatures were varied from 60 to 80 °C with various reaction periods. Small absorption shoulder of the CO stretching vibration was at 1700 cm-1, and slightly increased with the increase of the reaction time at 60 °C. The clear absorption peak appeared at 1698 cm-1 for the spheres reacted for 80 min at 70 °C and shifted toward 1720 cm-1 with the increase the reaction time. Strong absorption peak showed at 1698 cm-1 and shifted toward 1725 cm-1 with the increase of the reaction time at 80 °C. The spheres were dispersed to methanol and added photoinitiator (Irgacure-184). The solution was poured to a patterned glass substrate and exposed to the 254 nm UV-light during a self-assembly process. A large area and crack-free silica sphere film was formed. To increase the mechanical stability, a cellulose acetate solution was spin-coated to the film. The film was lift-off from the glass substrate to analyze the surface nanostructures. The surface nanostructures were maintained, and the film is stable enough to use as a mold to duplicate the nanopattern and flexible.

  5. Research and Development of Large Area Color AC Plasma Displays

    NASA Astrophysics Data System (ADS)

    Shinoda, Tsutae

    1998-10-01

    Plasma display is essentially a gas discharge device using discharges in small cavities about 0. 1 m. The color plasma displays utilize the visible light from phosphors excited by the ultra-violet by discharge in contrast to monochrome plasma displays utilizing visible light directly from gas discharges. At the early stage of the color plasma display development, the degradation of the phosphors and unstable operating voltage prevented to realize a practical color plasma display. The introduction of the three-electrode surface-discharge technology opened the way to solve the problems. Two key technologies of a simple panel structure with a stripe rib and phosphor alignment and a full color image driving method with an address-and-display-period-separated sub-field method have realized practically available full color plasma displays. A full color plasma display has been firstly developed in 1992 with a 21-in.-diagonal PDP and then a 42-in.-diagonal PDP in 1995 Currently a 50-in.-diagonal color plasma display has been developed. The large area color plasma displays have already been put into the market and are creating new markets, such as a wall hanging TV and multimedia displays for advertisement, information, etc. This paper will show the history of the surface-discharge color plasma display technologies and current status of the color plasma display.

  6. A Prototype Large Area Detector Module for Muon Scattering Tomography

    SciTech Connect

    Steer, C.A.; Boakes, J.; Burns, J.; Snow, S.; Stapleton, M.; Thompson, L.F.; Quillin, S.

    2015-07-01

    Abstract-Shielded special nuclear materials (SNM) are of concern as some fissile isotopes have low gamma and neutron emission rates. These materials are also easily shielded to the point where their passive emissions are comparable to background. Consequently, shielded SNM is very challenging for passive radiation detection portals which scan cargo containers. One potential solution for this is to utilise the natural cosmic ray muon background and examine how these muons scatter from materials inside the container volume, terms; the muon scattering tomography (MST) technique measures the three-dimensional localised scattering at all points within a cargo container, providing a degree of material discrimination. There is the additional benefit that the MST signal increases with the presence of more high density shielding materials, in contrast to passive radiation detection. Simulations and calculations suggest that the effectiveness of the technique is sensitive to the tracking accuracy amongst other parameters, motivating the need to develop practical detector systems that are capable of tracking cosmic ray muons. To this end, we have constructed and tested a 2 m by 2 m demonstration module based on gaseous drift chambers and triggered by a large area scintillator-based detector, which is readout by wavelength shifting fibres. We discuss its design, construction, characterisation and operational challenges. (authors)

  7. Attribution and Characterisation of Sclerophyll Forested Landscapes Over Large Areas

    NASA Astrophysics Data System (ADS)

    Jones, Simon; Soto-Berelov, Mariela; Suarez, Lola; Wilkes, Phil; Woodgate, Will; Haywood, Andrew

    2016-06-01

    This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI), bole density, canopy height), which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest). High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning) and researchers (RMIT, CRC for Spatial Information and CSIRO) conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet) scanners. Results are presented of: 1) inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2) canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3) time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS) with new aspirational targets of 5%). In this research we

  8. GLAST large area telescope - daily survey of high energy sky

    NASA Astrophysics Data System (ADS)

    Kamae, Tuneyoshi

    2003-07-01

    GLAST Large Area Telescope was proposed to NASA in 1999 as a follow-up of EGRET on-board Compton Gamma-Ray Observatory by an international collaboration. The proposal has been approved as a part of the GLAST observatory mission in its capability to explore a wide range of astrophysics with 5-40 times higher sensitivity and extended energy coverage (20MeV to 300GeV) than EGRET. The instrument consists of 16 towers of e+e- pair tracker, 16 blocks of segmented electro-magnetic calorimeter, and a set of anti-coicidence plastic scintillator tiles covering the tracker towers. It will have 5-10 times larger on-axis effective area, 6 times wider field-of-view (FOV), and up to 5 times better angular resolution when compared with EGRET. The Large Area Telescope will cover about 40% of the sky above the Earth's horizon in its FOV at any given time and will scan nearly the entire Universe every orbit (~ 90min): about 20% of Gamma-Ray Bursts will be observed from the onset of the bursts to the initial after-glow phase; all longer-lasting transients and variabilities will be detected daily at the improved sensitivity. The instrument has been prototyped twice between 1995 and 2001, designed almost to the Flight Model by the international collaboration of the US (NASA and DoE), France, Italy, Japan, and Sweden. The first prototype consisted of one tower of e+e- pair trackers, one block of segmented calorimeters and a smaller set of anti-coicidence plastic scintillator tiles (Beam Test Engineering Model, BTEM), which was put into e+, p, and γ beams at SLAC in the winter of 1999-2000. It was subsequently modified for a balloon experiment (Balloon Flight Engineering Model, BFEM) and flown at Palestine, Texas in August 2001. Data collected in the test experiments have been analyzed and compared with predictions of computer simulation codes such as Geant4. These studies have confirmed validity of the basic design, brought up a few issues for further improvement, and gathered data on

  9. Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

    PubMed

    Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

    2016-05-01

    Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service

  10. Design of a pentagonal photonic crystal fiber with high birefringence and large flattened negative dispersion.

    PubMed

    Li, Xuyou; Liu, Pan; Xu, Zhenlong; Zhang, Zhiyong

    2015-08-20

    Novel pentagonal photonic crystal fiber with high birefringence, large flattened negative dispersion, and high nonlinearity is proposed. The dispersion and birefringence properties of this structure are simulated and analyzed numerically based on the full vector finite element method (FEM). Numerical results indicate that the fiber obtains a large average dispersion of -611.9  ps/nm/km over 1,460-1,625 nm and -474  ps/nm/km over 1425-1675 nm wavelength bands for two kinds of optimized designs, respectively. In addition, the proposed PCF shows a high birefringence of 1.67×10-2 and 1.75×10-2 at the operating wavelength of 1550 nm. Moreover, the influence of the possible variation in the parameters during the fabrication process on the dispersion and birefringence properties is studied. The proposed PCF would have important applications in polarization maintaining transmission systems, residual dispersion compensation, supercontinuum generation, and the design of widely tunable wavelength converters based on four-wave mixing.

  11. MONITORING OF LARGE INSTABLE AREAS: system reliability and new tools.

    NASA Astrophysics Data System (ADS)

    Leandro, G.; Mucciarelli, M.; Pellicani, R.; Spilotro, G.

    2009-04-01

    The monitoring of unstable or potentially unstable areas is a necessary operation every time you can not remove the conditions of risk and apply to mitigation measures. In Italian Apennine regions there are many urban or extra-urban areas affected by instability, for which it is impracticable to remove hazard conditions, because of size and cost problems. The technological evolution exportable to the field of land instability monitoring is particularly lively and allows the use of warning systems unthinkable just few years ago. However, the monitoring of unstable or potentially unstable areas requires a very great knowledge of the specific problems, without which the reliability of the system may be dangerously overestimated. The movement may arise, indeed, in areas not covered by instrumentation, or covered with vegetation that prevents the acquisition of both reflected signals in the multi-beam laser techniques and radar signals. Environmental conditions (wind, concentrated sources of light, temperature changes, presence of animals) may also invalidate the accuracy of the measures, by introducing modulations or disturbance at a level well above the threshold of alarm signal, leading consequently to raise the values of the warning threshold. The Authors have gained long experience with the observation and monitoring of some large landslides in the Southern Apennine (Aliano, Buoninventre, Calciano, Carlantino, etc.) and unstable areas also at regional scale. One of the most important experiences is about the case of landslides of extensive areas, where unstable and stables zones coexist along transverse and longitudinal axis. In many of these cases you need the accurate control of the movement at selected points to evaluate the trend of displacement velocity, which can be achieved by means of a single-beam laser. The control of these movements, however, does not provide information on stress pattern into the stable areas. Among the sensitive precursors, acoustic

  12. Large-Area Permanent-Magnet ECR Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [<10(exp -4) torr (less than about 1.3 10(exp -2) Pa)] and input power <200 W at a frequency of 2.45 GHz. Though the prototype model operates at 2.45 GHz, operation at higher frequencies can be achieved by straightforward modification to the input microwave waveguide. Higher frequency operation may be desirable in those applications that require even higher background plasma densities. In the design of this ECR plasma source, there are no cumbersome, power-hungry electromagnets. The magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired

  13. SPLASH: Spitzer Large Area Survey with Hyper-Suprime-Cam

    NASA Astrophysics Data System (ADS)

    Capak, Peter; Aussel, Herve; Bundy, Kevin; Carollo, Marcella; Chary, Ranga Ram; Civano, Francesca; Coupon, Jean; Diener, Catrina; Donley, Jenifer; Dunlop, Jim; Elvis, Martin; Foucaud, Sebastien; Green, Jenny; Gunn, Jim; Hashimoto, Yasuhiro; Hassinger, Gunther; Hsieh, Bau-Ching; Huang, Lijin; Ilbert, Olivier; LeFloc'h, Emeric; LeFevre, Olivier; Lilly, Simon; Lin, Lihwai; Lin, Yen-Ting; Miyazaki, Satoshi; Mobasher, Bahram; Moriya, Takashi; Nagao, Tohru; Ono, Yoshiaki; Ouchi, Massami; Quimby, Robert; Saito, Tomoki; Salvato, Mara; Sanders, Dave; Schinnerer, Eva; Scoville, Nick; Shimasaku, Kazuhiro; Silverman, John; Smolcic, Vernesa; Strauss, Michael; Surace, Jason; Tanaka, Massayuki; Taniguchi, Yoshi; Teplitz, Harry; Wang, Wei-Hao; Urata, Yuji

    2012-09-01

    We propose a 2475h survey to build the foundation for comprehensive investigations of the earliest stages of galaxy, AGN and large-scale structure formation on cosmologically important scales, providing deep mid-IR imaging for two major 1.8deg^2 fields (COSMOS and SXDS). These two fields have been the target of, and are scheduled for, unparalleled deep imaging in the optical, sub-mm and radio. The Spitzer data is essential for immediate science goals and the legacy of these unique equatorial fields. The major science enabled by the proposed Spitzer observations includes: the co-evolution of cosmic large scale structure and the assembly and growth of galaxies and AGN; understanding the relative importance of smooth gas accretion vs. mergers for galaxy growth in the early universe; probing re-ionization through Infrared Background Fluctuations; constraining the Initial Mass Function at high redshift, AGN activity in the early universe, and the physics of supernova through transient studies. None of these are possible with existing Spitzer surveys, which are limited by both insufficient contiguous area, insufficient depth of ancillary data and/or temporal cadence. The two fields proposed here will have unique, Hyper-Suprime-Cam (HSC) imaging (to ~27-28 magAB for broad bands across the 0.4?1.0um wavelength range) and science will be immediately enabled by Spitzer using pre-existing deep X-ray to radio multi-wavelength data, including: UV (Galex), X-ray (Chandra/XMM), optical (HST), near-infrared, mid-Infrared (Spitzer/Herschel), sub-mm, and radio. The COSMOS field is the primary deep field for the Nu-Star mission and both fields have been ranked as high priority deep-field targets for Euclid. These fields also have extensive spectroscopy with Keck (>50nt), Subaru-FMOS (>30nt), VLT (>1000h), and are the primary targets for the future Subaru Prime Focus Spectrograph (PFS) surveys. The legacy impact of these data will be enormous, and will provide a treasure trove of

  14. Exploring Milkyway Halo Substructures with Large-Area Sky Surveys

    SciTech Connect

    Li, Ting

    2016-01-01

    Over the last two decades, our understanding of the Milky Way has been improved thanks to large data sets arising from large-area digital sky surveys. The stellar halo is now known to be inhabited by a variety of spatial and kinematic stellar substructures, including stellar streams and stellar clouds, all of which are predicted by hierarchical Lambda Cold Dark Matter models of galaxy formation. In this dissertation, we first present the analysis of spectroscopic observations of individual stars from the two candidate structures discovered using an M-giant catalog from the Two Micron All-Sky Survey. The follow-up observations show that one of the candidates is a genuine structure which might be associated with the Galactic Anticenter Stellar Structure, while the other one is a false detection due to the systematic photometric errors in the survey or dust extinction in low Galactic latitudes. We then presented the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first-year data of the Dark Energy Survey (DES) – a five-year, 5,000 deg2 optical imaging survey in the Southern Hemisphere. The Eridanus-Phoenix (EriPhe) overdensity is centered around l ~ 285° and b ~ -60° and the Poisson significance of the detection is at least 9σ. The EriPhe overdensity has a cloud-like morphology and the extent is at least ~ 4 kpc by ~ 3 kpc in projection, with a heliocentric distance of about d ~ 16 kpc. The EriPhe overdensity is morphologically similar to the previously-discovered Virgo overdensity and Hercules-Aquila cloud. These three overdensities lie along a polar plane separated by ~ 120° and may share a common origin. In addition to the scientific discoveries, we also present the work to improve the photometric calibration in DES using auxiliary calibration systems, since the photometric errors can cause false detection in first the halo substructure. We present a detailed description of the two

  15. Evaluating biodiversity conservation around a large Sumatran protected area.

    PubMed

    Linkie, Matthew; Smith, Robert J; Zhu, Yu; Martyr, Deborah J; Suedmeyer, Beth; Pramono, Joko; Leader-Williams, Nigel

    2008-06-01

    Many of the large, donor-funded community-based conservation projects that seek to reduce biodiversity loss in the tropics have been unsuccessful. There is, therefore, a need for empirical evaluations to identify the driving factors and to provide evidence that supports the development of context-specific conservation projects. We used a quantitative approach to measure, post hoc, the effectiveness of a US$19 million Integrated Conservation and Development Project (ICDP) that sought to reduce biodiversity loss through the development of villages bordering Kerinci Seblat National Park, a UNESCO World Heritage Site in Indonesia. We focused on the success of the ICDP component that disbursed a total of US$1.5 million through development grants to 66 villages in return for their commitment to stop illegally clearing the forest. To investigate whether the ICDP lowered deforestation rates in focal villages, we selected a subset of non-ICDP villages that had similar physical and socioeconomic features and compared their respective deforestation rates. Village participation in the ICDP and its development schemes had no effect on deforestation. Instead, accessible areas where village land-tenure had been undermined by the designation of selective-logging concessions tended to have the highest deforestation rates. Our results indicate that the goal of the ICDP was not met and, furthermore, suggest that both law enforcement inside the park and local property rights outside the park need to be strengthened. Our results also emphasize the importance of quantitative approaches in helping to inform successful and cost-effective strategies for tropical biodiversity conservation.

  16. Negative Associations between Corpus Callosum Midsagittal Area and IQ in a Representative Sample of Healthy Children and Adolescents

    PubMed Central

    Ganjavi, Hooman; Lewis, John D.; Bellec, Pierre; MacDonald, Penny A.; Waber, Deborah P.; Evans, Alan C.; Karama, Sherif

    2011-01-01

    Documented associations between corpus callosum size and cognitive ability have heretofore been inconsistent potentially owing to differences in sample characteristics, differing methodologies in measuring CC size, or the use of absolute versus relative measures. We investigated the relationship between CC size and intelligence quotient (IQ) in the NIH MRI Study of Normal Brain Development sample, a large cohort of healthy children and adolescents (aged six to 18, n = 198) recruited to be representative of the US population. CC midsagittal area was measured using an automated system that partitioned the CC into 25 subregions. IQ was measured using the Wechsler Abbreviated Scale of Intelligence (WASI). After correcting for total brain volume and age, a significant negative correlation was found between total CC midsagittal area and IQ (r = −0.147; p = 0.040). Post hoc analyses revealed a significant negative correlation in children (age<12) (r = −0.279; p = 0.004) but not in adolescents (age≥12) (r = −0.005; p = 0.962). Partitioning the subjects by gender revealed a negative correlation in males (r = −0.231; p = 0.034) but not in females (r = 0.083; p = 0.389). Results suggest that the association between CC and intelligence is mostly driven by male children. In children, a significant gender difference was observed for FSIQ and PIQ, and in males, a significant age-group difference was observed for FSIQ and PIQ. These findings suggest that the correlation between CC midsagittal area and IQ may be related to age and gender. PMID:21625542

  17. Negative pressure wound therapy combined with skin grafting improves surgical wound healing in the perianal area

    PubMed Central

    Jia-zi, Shi; Xiao, Zhai; Jun-hui, Li; Chun-yu, Xue; Hong-da, Bi

    2016-01-01

    Abstract Management of large tissue defects resulting from local wide resection of perianal is a clinical challenge for surgeons. The aim of the present study was to investigate the efficacy of negative pressure wound therapy (NPWT) following skin grafting on perianal surgical wound healing. Included in this study were 12 patients with perianal tumors who received skin grafting after perianal tumor resection between December 2012 and December 2014. A self-designed negative pressure drainage device was then applied to maintain a standard negative pressure at −150 mm Hg and removed on day 8 postoperation. The outcome was recorded immediately after NPWT and at 6-month follow-up. All skin grafts survived without infection, hematoma, and necrosis in all 12 patients. No tumor recurrence was detected during 6-month follow-up. Natural folds were observed around the anus. All patients showed normal bowel movements. NPWT following skin grafting was effective for perianal surgical wound healing and infection prevention, thus benefiting anatomical and functional recovery of the anus. PMID:27583890

  18. Automated Science Processing for the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Chiang, James

    2012-03-01

    The Large Area Telescope (LAT) onboard the Fermi γ-ray Space Telescope provides high sensitivity to emission from astronomical sources over a broad energy range (20MeV to >300 GeV) and has substantially improved spatial, energy, and timing resolution compared with previous observatories at these energies [4]. One of the LAT's most innovative features is that it performs continuous monitoring of the gamma-ray sky with all-sky coverage every 3 h. This survey strategy greatly enables the search for transient behavior from both previously known and unknown sources. In addition, the constant accumulation of data allows for increasingly improved measurements of persistent sources. These include the Milky Way Galaxy itself, which produces gamma-ray emission as a result from interactions of cosmic rays with gas in the Galaxy, and potential signals from candidate dark matter particles in the Milky Way and its neighboring galaxies. The automated science processing (ASP) functionality of the Fermi Instrument Science Operations Center (ISOC) is a part of the automated data pipeline that processes the raw data arriving from the spacecraft and puts it into a form amenable to scientific analysis. ASP operates at the end of the pipeline on the processed data and is intended to detect and characterize transient behavior (e.g., short time scale increases or “flares” in the gamma-ray flux) from astronomical sources. On detection of a flaring event, ASP will alert other observatories on a timely basis so that they may train their telescopes on the flaring source in order to detect possible correlated activity in other wavelength bands. Since the data from the LAT is archived and publicly available as soon as it is processed, ASP serves mainly to provide triggers for those follow-up observations; its estimates of the properties of the flaring sources (flux, spectral index, location) need not be the best possible, as subsequent off-line analysis can provide more refined

  19. The Spitzer-HETDEX Exploratory Large-area Survey

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; Lacy, M.; Ciardullo, R.; Finkelstein, S. L.; Bassett, R.; Behroozi, P.; Blanc, G. A.; de Jong, R. S.; DePoy, D. L.; Drory, N.; Gawiser, E.; Gebhardt, K.; Gronwall, C.; Hill, G. J.; Hopp, U.; Jogee, S.; Kawinwanichakij, L.; Marshall, J. L.; McLinden, E.; Mentuch Cooper, E.; Somerville, R. S.; Steinmetz, M.; Tran, K.-V.; Tuttle, S.; Viero, M.; Wechsler, R.; Zeimann, G.

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ˜ 800 spectroscopy will produce ˜200,000 redshifts from the Lyα emission for galaxies in the range 1.9 < z < 3.5, and an additional ˜200,000 redshifts from the [O ii] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ˜0.5 Gpc3 at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μm images. The catalogs reach limiting sensitivities of 1.1 μJy at both 3.6 and 4.5 μm (1σ, for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  20. Facile Assembly of Large-Area 2D Microgel Colloidal Crystals Using Charge-Reversible Substrates.

    PubMed

    Weng, Junying; Li, Xiaoyun; Guan, Ying; Zhu, X X; Zhang, Yongjun

    2016-12-06

    2D colloidal crystals (CCs) have important applications; however, the fabrication of large-area, high-quality 2D CCs is still far from being trivial, and the fabrication of 2D microgel CCs is even harder. Here, we have demonstrated that they can be facilely fabricated using charge-reversible substrates. The charge-reversible substrates were prepared by modification with amino groups. The amino groups were then protected by amidation with 2,2-dimethylsuccinic anhydride. At acidic pH, the surface charge of the modified substrate will change from negative to positive as a result of the hydrolysis of the amide bonds and the regeneration of the amino groups. 2D microgel CCs can be simply fabricated by applying a concentrated microgel dispersion on the modified substrate. The negatively charged surface of the substrate allows the negatively charged microgel spheres, especially those close to the substrate, to self-assemble into 3D CCs. With the gradual hydrolysis of the amide bonds and the charge reversal of the substrate, the first 111 plane of the 3D assembly is fixed in situ on the substrate. The resulting 2D CC has a high degree of ordering because of the high quality of the parent 3D microgel CC. Because large-area 3D microgel CCs can be facilely fabricated, this method allows for the fabrication of 2D CCs of any size. Nonplanar substrates can also be used. In addition, the interparticle distance of the 2D array can be tuned by the concentration of the microgel dispersion. Besides rigid substrates (such as glass slides, quartz slides, and silicon wafers), flexible polymer films, including polyethylene terephthalate and poly(vinyl chloride) films, were also successfully used as substrates for the fabrication of 2D microgel CCs.

  1. Large area controlled assembly of transparent conductive networks

    DOEpatents

    Ivanov, Ilia N.; Simpson, John T.

    2015-09-29

    A method of preparing a network comprises disposing a solution comprising particulate materials in a solvent onto a superhydrophobic surface comprising a plurality of superhydrophobic features and interfacial areas between the superhydrophobic features. The plurality of superhydrophobic features has a water contact angle of at least about 150.degree.. The method of preparing the network also comprises removing the solvent from the solution of the particulate materials, and forming a network of the particulate materials in the interfacial areas, the particulate materials receding to the interfacial areas as the solvent is removed.

  2. Cause of large negative Eu anomaly in the highly evolved A-type granites with REE tetrad pattern

    NASA Astrophysics Data System (ADS)

    Lee, S.; Asahara, Y.; Tanaka, T.; Lee, M.; Lee, S. R.

    2013-12-01

    REE tetrad pattern with strongly large negative Eu anomaly is one of the specific geochemical phenomena observed in the highly evolved, fractionated granite or A-type granite. The large negative Eu anomaly from the highly evolved or fractionated granites related with REE tetrad effect was discussed in a lot of literatures (e.g. [1] Muecke and Clarke, 1981; [2] Irber, 1999; [3] Jahn et al., 2001). Recently, Lee et al.[4] also suggested that Eu anomalies and REE tetrad pattern from the highly fractionated A-type Muamsa and Weolaksan granites in the Okcheon Metamorphic Belt, Korea, might be associated with a fractionation between the residual melt and a coexisting aqueous high temperature fluid. Their origin and geochemical significance are ongoing yet. In order to clarify cause of large negative Eu anomaly in the granite with REE tetrad effect more clearly, we reanalyzed REE abundance of the Muamsa and Weolaksan granites using MC-ICP-MS at the origins laboratory of the University of Chicago. We also measured REE abundances of the constituent minerals using quadruple ICP-MS at the Korea Polar Research Institute. In this report, we show the re-analyzed REE data from the whole rock as well as new REE data from constituent minerals of the granite with REE tetrad effect. Then, we discuss the cause of large negative Eu anomaly in the highly evolved granite with REE tetrad effect. Especially, the granites with very large negative Eu anomaly also show large negative Ce anomaly. Lee et al. [4] mentioned that negative Ce anomalies were formed after granite emplacement. However, our new data indicate that negative Ce anomaly might be formed during the same geochemical process with very large negative Eu anomaly. This suggests that the REE tetrad effect may be related with a change of oxidation state during a magma evolution. Therefore, we will discuss REE tetrad effect, negative Eu and Ce anomaly as an indicator for the change of oxidation state of magma during the emplacement

  3. Large area solar power heliostat array for OSETI

    NASA Astrophysics Data System (ADS)

    Covault, Corbin E.

    2001-08-01

    Current OSETI programs make use of optical telescopes with light collection areas on the order of 10 square meters or less. The small collection area limits the ultimate sensitivity achievable to low-intensity signals. However, solar power facilities such as the National Solar Thermal Test Facility (NSTTF) provide the potential for a much larger collecting area. The NSTTF is operated at by the Department of Energy at Sandia National Laboratories for research in solar power development and testing. The NSTTF site includes over 200 fully steerable mirrors (called heliostats) each providing 37 square meters of collecting area. This facility is currently being used at night for gamma-ray astronomy. The STACEE experiment makes use of 64 heliostats to detect nanosecond flashes of optical Cherenkov light associated with gamma-ray air showers from the top of the atmosphere. The STACEE experiment has been in operation since 1998 and has already detected gamma-rays from the Crab Nebula. In principle, the STACEE experiment can be operated with minor modifications to detect OSETI signals on the ground at a photon density of less than two optical photons per square meter per pulse. We summarize performance results from the STACEE experiment, and we discuss the sensitivity of a hypothetical future STACEE-OSETI experiment with particular attention to potential sources of background.

  4. Direct single-molecule observations of DNA unwinding by SV40 large tumor antigen under a negative DNA supercoil state.

    PubMed

    Takahashi, Shunsuke; Motooka, Shinya; Kawasaki, Shohei; Kurita, Hirofumi; Mizuno, Takeshi; Matsuura, Shun-Ichi; Hanaoka, Fumio; Mizuno, Akira; Oshige, Masahiko; Katsura, Shinji

    2017-01-05

    Superhelices, which are induced by the twisting and coiling of double-helical DNA in chromosomes, are thought to affect transcription, replication, and other DNA metabolic processes. In this study, we report the effects of negative supercoiling on the unwinding activity of simian virus 40 large tumor antigen (SV40 TAg) at a single-molecular level. The supercoiling density of linear DNA templates was controlled using magnetic tweezers and monitored using a fluorescent microscope in a flow cell. SV40 TAg-mediated DNA unwinding under relaxed and negative supercoil states was analyzed by the direct observation of both single- and double-stranded regions of single DNA molecules. Increased negative superhelicity stimulated SV40 TAg-mediated DNA unwinding more strongly than a relaxed state; furthermore, negative superhelicity was associated with an increased probability of SV40 TAg-mediated DNA unwinding. These results suggest that negative superhelicity helps to regulate the initiation of DNA replication.

  5. [Spatiotemporal distribution of negative air ion concentration in urban area and related affecting factors: a review].

    PubMed

    Huang, Xiang-Hua; Wang, Jian; Zeng, Hong-Da; Chen, Guang-Shui; Zhong, Xian-Fang

    2013-06-01

    Negative air ion (NAI) concentration is an important indicator comprehensively reflecting air quality, and has significance to human beings living environment. This paper summarized the spatiotemporal distribution features of urban NAI concentration, and discussed the causes of these features based on the characteristics of the environmental factors in urban area and their effects on the physical and chemical processes of NAI. The temporal distribution of NAI concentration is mainly controlled by the periodic variation of solar radiation, while the spatial distribution of NAI concentration along the urban-rural gradient is mainly affected by the urban aerosol distribution, underlying surface characters, and urban heat island effect. The high NAI concentration in urban green area is related to the vegetation life activities and soil radiation, while the higher NAI concentration near the water environment is attributed to the water molecules that participate in the generation of NAI through a variety of ways. The other environmental factors can also affect the generation, life span, component, translocation, and distribution of NAI to some extent. To increase the urban green space and atmospheric humidity and to maintain the soil natural attributes of underlying surface could be the effective ways to increase the urban NAI concentration and improve the urban air quality.

  6. Existence domains of large amplitude dust-acoustic solitons in non-thermal plasmas with positive and negative dust

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.; Pillay, S. R.

    2011-11-29

    Using the traditional Sagdeev pseudopotential approach, the existence of large amplitude solitons is investigated for a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons. The lower and upper soliton Mach number limitations are determined as a function of various parameters and physical reasons are provided as to why these Mach number limits occur. Some regions in parameter space have been identified where only negative or positive solitons occur, whereas, other regions support the coexistence of both positive and negative potential solitons.

  7. Existence domains of large amplitude dust-acoustic solitons in non-thermal plasmas with positive and negative dust

    NASA Astrophysics Data System (ADS)

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.

    2011-11-01

    Using the traditional Sagdeev pseudopotential approach, the existence of large amplitude solitons is investigated for a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons. The lower and upper soliton Mach number limitations are determined as a function of various parameters and physical reasons are provided as to why these Mach number limits occur. Some regions in parameter space have been identified where only negative or positive solitons occur, whereas, other regions support the coexistence of both positive and negative potential solitons.

  8. Large Mode Area Yb-Doped Photonic Bandgap Fiber Lasers

    DTIC Science & Technology

    2015-02-08

    ABSTRACT 16. SECURITY CLASSIFICATION OF: All-solid photonic bandgap fibers (PBGF) can be spectrally tailored to suppress amplified spontaneous emission...ASE) and stimulated Raman scattering (SRS). Furthermore, this type of fiber is attractive for realizing high-power narrow-linewidth amplifiers as...area Yb-doped photonic bandgap fiber lasers Report Title All-solid photonic bandgap fibers (PBGF) can be spectrally tailored to suppress amplified

  9. A large area transition radiation detector for the NOMAD experiment

    NASA Astrophysics Data System (ADS)

    Bassompierre, G.; Bermond, M.; Berthet, M.; Bertozzi, T.; Détraz, C.; Dubois, J.-M.; Dumps, L.; Engster, C.; Fazio, T.; Gaillard, G.; Gaillard, J.-M.; Gouanère, M.; Manola-Poggioli, E.; Mossuz, L.; Mendiburu, J.-P.; Nédélec, P.; Palazzini, E.; Pessard, H.; Petit, P.; Petitpas, P.; Placci, A.; Sillou, D.; Sottile, R.; Valuev, V.; Verkindt, D.; Vey, H.; Wachnik, M.

    1998-02-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  10. Large seasonal swings in leaf area of Amazon rainforests.

    PubMed

    Myneni, Ranga B; Yang, Wenze; Nemani, Ramakrishna R; Huete, Alfredo R; Dickinson, Robert E; Knyazikhin, Yuri; Didan, Kamel; Fu, Rong; Negrón Juárez, Robinson I; Saatchi, Sasan S; Hashimoto, Hirofumi; Ichii, Kazuhito; Shabanov, Nikolay V; Tan, Bin; Ratana, Piyachat; Privette, Jeffrey L; Morisette, Jeffrey T; Vermote, Eric F; Roy, David P; Wolfe, Robert E; Friedl, Mark A; Running, Steven W; Votava, Petr; El-Saleous, Nazmi; Devadiga, Sadashiva; Su, Yin; Salomonson, Vincent V

    2007-03-20

    Despite early speculation to the contrary, all tropical forests studied to date display seasonal variations in the presence of new leaves, flowers, and fruits. Past studies were focused on the timing of phenological events and their cues but not on the accompanying changes in leaf area that regulate vegetation-atmosphere exchanges of energy, momentum, and mass. Here we report, from analysis of 5 years of recent satellite data, seasonal swings in green leaf area of approximately 25% in a majority of the Amazon rainforests. This seasonal cycle is timed to the seasonality of solar radiation in a manner that is suggestive of anticipatory and opportunistic patterns of net leaf flushing during the early to mid part of the light-rich dry season and net leaf abscission during the cloudy wet season. These seasonal swings in leaf area may be critical to initiation of the transition from dry to wet season, seasonal carbon balance between photosynthetic gains and respiratory losses, and litterfall nutrient cycling in moist tropical forests.

  11. A new approach to large area microchannel plate manufacture

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Methods of manufacture of twisted single elements as the base for producing microchannel plates (MCP) are discussed. Initial evaluations validated the off-axis channel concept and no technological roadblocks were identified which would prevent fabrication of high gain, high spatial resolution, large format MCP's using this technique. The first MP's have operated at stable gains of 3 million with pulse height resolution superior to results obtained by standard chevron MCP's.

  12. High resolution, large area, high energy x-ray tomography

    SciTech Connect

    Trebes, J.E.; Dolan, K.W.; Haddad, W.S.; Haskins, J.J.; Lerche, R.A.; Logan, C.M.; Perkins, D.E.; Schneberk, D.J.; Rikard, R.D.

    1997-08-01

    An x-ray tomography system is being developed for high resolution inspection of large objects. The goal is to achieve 25 micron resolution over object sizes that are tens of centimeters in extent. Typical objects will be metal in composition and therefore high energy, few MeV x-rays will be required. A proof-of-principle system with a limited field of view has been developed. Preliminary results are presented.

  13. Heat-Pipe Array for Large-Area Cooling

    NASA Technical Reports Server (NTRS)

    Edelstein, F.; Brown, R. F.

    1986-01-01

    High rates of heat transfer anticipated. Prototype evaporative cold plate gathers waste heat from equipment mounted on it. Plate made by welding together flanges of several sections of heat pipe. Since plate separates liquid and vapor phases at inlet and outlet ports, eliminates complexities and uncertainties of two-phase flow in zero gravity. On earth, inlet valve enables plate to operate at relatively-large height differences with other plates in same system.

  14. Modeling positive Granger causality and negative phase lag between cortical areas.

    PubMed

    Matias, Fernanda S; Gollo, Leonardo L; Carelli, Pedro V; Bressler, Steven L; Copelli, Mauro; Mirasso, Claudio R

    2014-10-01

    Different measures of directional influence have been employed to infer effective connectivity in the brain. When the connectivity between two regions is such that one of them (the sender) strongly influences the other (the receiver), a positive phase lag is often expected. The assumption is that the time difference implicit in the relative phase reflects the transmission time of neuronal activity. However, Brovelli et al. (2004) observed that, in monkeys engaged in processing a cognitive task, a dominant directional influence from one area of sensorimotor cortex to another may be accompanied by either a negative or a positive time delay. Here we present a model of two brain regions, coupled with a well-defined directional influence, that displays similar features to those observed in the experimental data. This model is inspired by the theoretical framework of Anticipated Synchronization developed in the field of dynamical systems. Anticipated Synchronization is a form of synchronization that occurs when a unidirectional influence is transmitted from a sender to a receiver, but the receiver leads the sender in time. This counterintuitive synchronization regime can be a stable solution of two dynamical systems coupled in a master-slave (sender-receiver) configuration when the slave receives a negative delayed self-feedback. Despite efforts to understand the dynamics of Anticipated Synchronization, experimental evidence for it in the brain has been lacking. By reproducing experimental delay times and coherence spectra, our results provide a theoretical basis for the underlying mechanisms of the observed dynamics, and suggest that the primate cortex could operate in a regime of Anticipated Synchronization as part of normal neurocognitive function.

  15. Progress in amorphous silicon based large-area multijunction modules

    NASA Astrophysics Data System (ADS)

    Carlson, D. E.; Arya, R. R.; Bennett, M.; Chen, L.-F.; Jansen, K.; Li, Y.-M.; Maley, N.; Morris, J.; Newton, J.; Oswald, R. S.; Rajan, K.; Vezzetti, D.; Willing, F.; Yang, L.

    1996-01-01

    Solarex, a business unit of Amoco/Enron Solar, is scaling up its a-Si:H/a-SiGe:H tandem device technology for the production of 8 ft2 modules. The current R&D effort is focused on improving the performance, reliability and cost-effectiveness of the tandem junction technology by systematically optimizing the materials and interfaces in small-area single- and tandem junction cells. Average initial conversion efficiencies of 8.8% at 85% yield have been obtained in pilot production runs with 4 ft2 tandem modules.

  16. Large-Area Laser-Lift-Off Processing in Microelectronics

    NASA Astrophysics Data System (ADS)

    Delmdahl, R.; Pätzel, R.; Brune, J.

    Laser lift-off is an enabling technology for microelectronics growth markets such as light emitting diodes, densely packaged semiconductor devices, and flexible displays. For example, thin film transistor structures fabricated on top of polymer layers spun on glass carriers must be delaminated from rigid substrates to create lightweight and rugged flexible displays on polymers. Low-thermal-budget processes are generically required to protect adjacent functional films. Excimer lasers provide short UV wavelength and short pulse duration required for highly-localized energy coupling. The high output power of excimer lasers enables a large processing footprint and the high-throughput rates needed in mass manufacturing.

  17. Large area low-cost space solar cell development

    NASA Technical Reports Server (NTRS)

    Barona, C. R.; Cioni, J. L.

    1982-01-01

    A development program to produce 5.9 x 5.9 cm space quality silicon solar cells with a cost goal of 30 $/W is described. Cell types investigated include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm/cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover glass simultaneously is being developed. Results for cell and array tests are given. Large solar arrays that might use cells of this type are discussed.

  18. Acrolein Microspheres Are Bonded To Large-Area Substrates

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  19. Large area spark counter with fine time and position resolution

    SciTech Connect

    Ogawa, A.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1984-03-01

    The key properties of spark counters include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. Some details of its construction and its properties as a particle detector are reported. 14 references. (WHK)

  20. Evaluation of Overall Insolation Fluctuation Property Considering Insolation Fluctuation Independence among Various Points in Large Area

    NASA Astrophysics Data System (ADS)

    Kato, Takeyoshi; Inoue, Takato; Suzuoki, Yasuo

    Power output fluctuation of photovoltaic power generation systems (PVSs) of high penetration may cause negative impact on the load frequency control (LFC) of existing electric power utility. For the cost-effective mitigation, the proper evaluation of power output fluctuation of PVSs dispersed in large-area is very important. Based on the independence in insolation fluctuation among various points, this paper discusses the practical usability of the standard deviation (STD) of total power output fluctuation of PVSs simply calculated as 1/√N value of STD at the representative point. The statistical evaluation using the insolation observed at 5 points within 25km × 25km reveals that STD with simplified calculation would be useful to evaluate STD of ensemble average of insolation on average for a certain period. Besides, the probability density of STD with simplified calculation is almost the same with that of STD of ensemble average for the period with large STD. As a result, the simplified calculation of STD would be useful for the stochastic evaluation of STD of ensemble average insolation among area at least 25km × 25km.

  1. Multicore Large-Scale Integration Lifetime Extension by Negative Bias Temperature Instability Recovery-Based Self-Healing

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takashi; Makino, Hiroaki; Kobayashi, Kazutoshi; Onodera, Hidetoshi

    2012-04-01

    We propose a multicore large-scale integration (LSI) lifetime extension method, which is based on negative bias temperature instability (NBTI) recovery-based self-healing and circuit parallelization. NBTI recovery is characterized by the recently proposed NBTI sensor with 400 ns measurement delay that measures the off-leak current of p-channel metal-oxide-semiconductor (PMOS) transistors. The circuit is fabricated in a commercial 65 nm complementary MOS (CMOS) technology. It is found that the recoverable component of the LSI performance characterized by the off-leak current remains almost constant after repeatedly adding NBTI stress. The NBTI stress corresponds to circuit operation for several years at room temperature and a nominal operating voltage. It is also found that the amount of NBTI recovery can be tuned by the relaxation time in a real application, and it follows log t from 400 ns to 3000 s. It is shown that for multicore LSI, by recovering one of the n + 1 cores, the n-core LSI system does not stop and the lifetime can be extended by NBTI recovery. For the first time, transforming silicon area into LSI reliability is shown to be a promising and realistic concept for the ever-shrinking CMOS technology.

  2. Andean Basins Morphometry: Assesing South American Large Rivers' Source Areas

    NASA Astrophysics Data System (ADS)

    Bean, R. A.; Latrubesse, E. M.

    2014-12-01

    Presently there are no regional-scale morphometric analyses of Andean fluvial basins. Therefore, we created a continental-scale database of these basins. Our data covers over an area 1,000,000 km2 of the Andes, from Venezuela to Argentina. These basins are the source of some of the largest rivers in the world including the Amazon, Orinoco, Parana, and Magdalena. Morphometric parameters including shape factor, relief ratio, longitudinal profiles and different indices of basin elevation were calculated based on the CGIAR SRTM 4.1 DEM (~90 m resolution). FAO Hydrosheds were used to segment the DEM by major catchment and then manually cut at the Andean zone. In the North and Central Andes, this produced over 500,000 subcatchments, which we reduced to 619 by setting minimum catchment area to 100 km2. We then integrate lithologic data from DNPM geologic data. Our results indicate that sedimentary lithologies dominate Central Andean catchments (n=268,k=4), which cover an area 767,00 km2, while the Northern Andean catchments (covering 350,000 km2) are more varied, dominated by volcanics in the Pacific (n=78), a sedimentary (48%) dominant mix in the Caribbean (n=138) and 60% sedimentary in the Amazon-Orinoco subregion catchments (n=138). Elevation averages are smallest in the north Andes and average maximum elevations (6,026 m) in the Argentinian catchments (n=65) of the Central Andes are the highest. Shape factors range from 0.49 to 0.58 in the North and 0.52 to 0.58 in the Central Andes. There are clear differences in all categories between region and subregion, but that difference does not hinge on a single morphometric or geologic parameter. Morphometric parameters at a watershed scale (listed in Table) are analyzed and hydrologic data from gauging stations throughout the Andes (n=100) are used to compare morphometric parameters with lithology and characteristics from the basin hydrograph (peak discharge timing, minimum and maximum discharge, and runoff).

  3. LSSA large area silicon sheet task continuous Czochralski process development

    NASA Technical Reports Server (NTRS)

    Rea, S. N.

    1978-01-01

    A Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a premelter to provide molten silicon flow into the primary crucible. The basic furnace is operational and several trial crystals were grown in the batch mode. Numerous premelter configurations were tested both in laboratory-scale equipment as well as in the actual furnace. The best arrangement tested to date is a vertical, cylindrical graphite heater containing small fused silicon test tube liner in which the incoming silicon is melted and flows into the primary crucible. Economic modeling of the continuous Czochralski process indicates that for 10 cm diameter crystal, 100 kg furnace runs of four or five crystals each are near-optimal. Costs tend to asymptote at the 100 kg level so little additional cost improvement occurs at larger runs. For these conditions, crystal cost in equivalent wafer area of around $20/sq m exclusive of polysilicon and slicing was obtained.

  4. Wide-area ATM networking for large-scale MPPs

    SciTech Connect

    Papadopoulos, P.M.; Geist, G.A. II

    1997-04-01

    This paper presents early experiences with using high-speed ATM interfaces to connect multiple Intel Paragons on both local and wide area networks. The testbed includes the 1024 and 512 node Paragons running the OSF operating system at Oak Ridge National Laboratory and the 1840 node Paragon running the Puma operating system at Sandia National Laboratories. The experimental OC-12 (622 Mbits/sec) interfaces are built by GigaNet and provide a proprietary API for sending AAL-5 encapsulated packets. PVM is used as the massaging infrastructure and significant modifications have been made to use the GigaNet API, operate in the Puma environment, and attain acceptable performance over local networks. These modifications are described along with a discussion of roadblocks to networking MPPs with high-performance interfaces. Our early prototype utilizes approximately 25 percent of an OC-12 circuit and 80 percent of an OC-3 circuit in send plus acknowledgment ping-pong tests.

  5. Cosmic ray tests of large area Multigap Resistive Plate Chambers

    NASA Astrophysics Data System (ADS)

    An, Shaohui; Hatzifotiadou, D.; Kim, Jinsook; Williams, M. C. S.; Zichichi, A.; Zuyeuski, R.

    2007-07-01

    We have built Multigap Resistive Plate Chambers (MRPC) with six 300 μm gas gaps and an active area of 158×82 cm2. The signals are generated on 2.5 cm wide copper pickup strips; these are read out at each end thus allowing the position of the hit along the strip to be obtained from the time difference. Using three of these chambers we have set up a cosmic tracking system in a similar manner as planned for the Extreme Energy Events (EEE) project. The details of the set-up are presented in this paper. In addition we discuss the time and position resolution of these MRPCs measured using cosmic rays.

  6. Large-area sheet task advanced dendritic web growth development

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.

    1984-01-01

    The thermal models used for analyzing dendritic web growth and calculating the thermal stress were reexamined to establish the validity limits imposed by the assumptions of the models. Also, the effects of thermal conduction through the gas phase were evaluated and found to be small. New growth designs, both static and dynamic, were generated using the modeling results. Residual stress effects in dendritic web were examined. In the laboratory, new techniques for the control of temperature distributions in three dimensions were developed. A new maximum undeformed web width of 5.8 cm was achieved. A 58% increase in growth velocity of 150 micrometers thickness was achieved with dynamic hardware. The area throughput goals for transient growth of 30 and 35 sq cm/min were exceeded.

  7. Embedded graphene for large-area silicon-based devices

    NASA Astrophysics Data System (ADS)

    Gluba, M. A.; Amkreutz, D.; Troppenz, G. V.; Rappich, J.; Nickel, N. H.

    2013-08-01

    Macroscopic graphene films buried below amorphous and crystalline silicon capping layers are studied by Raman backscattering spectroscopy and Hall-effect measurements. The graphene films are grown by chemical vapor deposition on copper foil and transferred to glass substrates. Uncapped films possess charge-carrier mobilities of 2030 cm2/Vs at hole concentrations of 3.6 × 1012 cm-2. Graphene withstands the deposition and subsequent crystallization of silicon capping layers. However, the crystallinity of the silicon cap has large influence on the field-induced doping of graphene. Temperature dependent Hall-effect measurements reveal that the mobility of embedded graphene is limited by charged-impurity and phonon-assisted scattering.

  8. Large area spark counters with fine time and position resolution

    SciTech Connect

    Ogawa, A.; Atwood, W.B.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1983-10-01

    Spark counters trace their history back over three decades but have been used in only a limited number of experiments. The key properties of these devices include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. In this talk I will discuss some details of its construction and its properties as a particle detector. 14 references.

  9. Negative symptoms in schizophrenia: a study in a large clinical sample of patients using a novel automated method

    PubMed Central

    Patel, Rashmi; Jayatilleke, Nishamali; Broadbent, Matthew; Chang, Chin-Kuo; Foskett, Nadia; Gorrell, Genevieve; Hayes, Richard D; Jackson, Richard; Johnston, Caroline; Shetty, Hitesh; Roberts, Angus; McGuire, Philip; Stewart, Robert

    2015-01-01

    Objectives To identify negative symptoms in the clinical records of a large sample of patients with schizophrenia using natural language processing and assess their relationship with clinical outcomes. Design Observational study using an anonymised electronic health record case register. Setting South London and Maudsley NHS Trust (SLaM), a large provider of inpatient and community mental healthcare in the UK. Participants 7678 patients with schizophrenia receiving care during 2011. Main outcome measures Hospital admission, readmission and duration of admission. Results 10 different negative symptoms were ascertained with precision statistics above 0.80. 41% of patients had 2 or more negative symptoms. Negative symptoms were associated with younger age, male gender and single marital status, and with increased likelihood of hospital admission (OR 1.24, 95% CI 1.10 to 1.39), longer duration of admission (β-coefficient 20.5 days, 7.6–33.5), and increased likelihood of readmission following discharge (OR 1.58, 1.28 to 1.95). Conclusions Negative symptoms were common and associated with adverse clinical outcomes, consistent with evidence that these symptoms account for much of the disability associated with schizophrenia. Natural language processing provides a means of conducting research in large representative samples of patients, using data recorded during routine clinical practice. PMID:26346872

  10. SPLASH: Spitzer Large Area Survey with Hyper-Suprime-Cam

    NASA Astrophysics Data System (ADS)

    Capak, Peter; Aussel, Herve; Bundy, Kevin; Bethermin, Matthieu; Carollo, Marcella; Chary, Ranga-Ram; Civano, Francesca; Coupon, Jean; Diener, Catrina; Donley, Jennifer; Dunlop, Jim; Elvis, Martin; Faisst, Andreas; Foucaud, Sebastien; Green, Jenny; Gunn, Jim; Hashimoto, Yasuhiro; Hassinger, Gunther; Hsieh, Bau-Ching; Huang, Lijin; Ilbert, Olivier; LeFloc'h, Emeric; LeFevre, Olivier; Lilly, Simon; Lin, Lihwai; Lin, Yen-Ting; Miyazaki, Satoshi; Mobasher, Bahram; Moriya, Takashi; Nagao, Tohru; Ono, Yoshiaki; Ouchi, Massami; Petric, Andrea; Pych, Wojtek; Quimby, Robert; Saito, Tomoki; Salvato, Mara; Sanders, Dave; Scarlata, Claudia; Schinnerer, Eva; Scoville, Nick; Sheth, Kartik; Shimasaku, Kazuhiro; Silverman, John; Smolcic, Vernesa; Steinhardt, Charles; Strauss, Michael; Surace, Jason; Tanaka, Masaomi; Tanaka, Massayuki; Taniguchi, Yoshi; Teplitz, Harry; Toshida, Naoki; Wang, Wei-Hao; Urata, Yuji

    2013-10-01

    We propose 1650h to complete SPLASH, building a foundation for comprehensive investigations of the earliest stages of galaxy, AGN and large-scale structure formation on cosmologically important scales, providing deep mid-IR imaging for two major 1.8deg^2 fields (COSMOS and SXDS). These two fields have been the target of, and are scheduled for, unparalleled deep imaging in the optical, sub-mm and radio. The Spitzer data are essential for immediate science goals and the legacy of these unique equatorial fields. The major science enabled by the proposed Spitzer observations includes: the co-evolution of cosmic large scale structure and the assembly and growth of galaxies and AGN; understanding the relative importance of smooth gas accretion vs. mergers for galaxy growth in the early universe; probing re-ionization through Infrared Background Fluctuations; constraining the Initial Mass Function at high redshift, AGN activity in the early universe, and the physics of supernova through transient studies. None of these are possible with existing Spitzer surveys. The two fields proposed here will have unique, Hyper-Suprime-Cam (HSC) imaging (to ~27-28 magAB for broad bands across the 0.4-1.0um wavelength range) and science will be immediately enabled by Spitzer using pre-existing deep X-ray to radio multi-wavelength data, including: UV (Galex), X-ray (Chandra/XMM), optical (HST), near-infrared, mid-Infrared (Spitzer/Herschel), sub-mm, and radio. The COSMOS field is the primary deep field for the Nu-Star mission and both fields have been ranked as high priority deep-field targets for Euclid. These fields also have extensive spectroscopy with Keck (>50nt), Subaru-FMOS (>30nt), VLT (>1000h), and are the primary targets for the future Subaru Prime Focus Spectrograph (PFS) surveys. The legacy impact of these data will be enormous, and will provide a treasure trove of targets for JWST. This is part 1 (SXDS) of the awarded time.

  11. Large-Area Semiconducting Graphene Nanomesh Tailored by Interferometric Lithography

    PubMed Central

    Kazemi, Alireza; He, Xiang; Alaie, Seyedhamidreza; Ghasemi, Javad; Dawson, Noel Mayur; Cavallo, Francesca; Habteyes, Terefe G.; Brueck, Steven R. J.; Krishna, Sanjay

    2015-01-01

    Graphene nanostructures are attracting a great deal of interest because of newly emerging properties originating from quantum confinement effects. We report on using interferometric lithography to fabricate uniform, chip-scale, semiconducting graphene nanomesh (GNM) with sub-10 nm neck widths (smallest edge-to-edge distance between two nanoholes). This approach is based on fast, low-cost, and high-yield lithographic technologies and demonstrates the feasibility of cost-effective development of large-scale semiconducting graphene sheets and devices. The GNM is estimated to have a room temperature energy bandgap of ~30 meV. Raman studies showed that the G band of the GNM experiences a blue shift and broadening compared to pristine graphene, a change which was attributed to quantum confinement and localization effects. A single-layer GNM field effect transistor exhibited promising drive current of ~3.9 μA/μm and ON/OFF current ratios of ~35 at room temperature. The ON/OFF current ratio of the GNM-device displayed distinct temperature dependence with about 24-fold enhancement at 77 K. PMID:26126936

  12. 77 FR 32022 - Direct Final Negative Declaration and Withdrawal of Large Municipal Waste Combustors State Plan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-31

    ... Agency (EPA). ACTION: Direct final rule. SUMMARY: EPA is taking direct final action to approve Illinois' negative declaration and request for EPA withdrawal of its 111(d)/129 State Plan to control air pollutants... 111(d) and 129 of the Clean Air Act require submittal of State plans to control certain...

  13. A large area, silicon photomultiplier-based PET detector module.

    PubMed

    Raylman, Rr; Stolin, A; Majewski, S; Proffitt, J

    2014-01-21

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm(2) LYSO elements (spanning 41 × 91mm(2)) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner.

  14. The Negative Binomial Distribution as a Renewal Model for the Recurrence of Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Tejedor, Alejandro; Gómez, Javier B.; Pacheco, Amalio F.

    2015-01-01

    The negative binomial distribution is presented as the waiting time distribution of a cyclic Markov model. This cycle simulates the seismic cycle in a fault. As an example, this model, which can describe recurrences with aperiodicities between 0 and 0.5, is used to fit the Parkfield, California earthquake series in the San Andreas Fault. The performance of the model in the forecasting is expressed in terms of error diagrams and compared with other recurrence models from literature.

  15. Large negative Goos-Hänchen shift from a weakly absorbing dielectric slab.

    PubMed

    Wang, Li-Gang; Chen, Hong; Zhu, Shi-Yao

    2005-11-01

    It is theoretically shown that the negative Goos-Hänchen shifts near resonance, Re[k(z)d] = m pi, can be an order of magnitude larger than the wavelength for both TE- and TM-polarized beams reflected from a weakly absorbing dielectric slab if the absorption of the slab is sufficiently weak, which is different from the case for a lossless dielectric slab [Phys. Rev. Lett. 91, 133903 (2003)].

  16. Composite flexible skin with large negative Poisson’s ratio range: numerical and experimental analysis

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Scarpa, F.; Farrow, I. R.; Liu, Y. J.; Leng, J. S.

    2013-04-01

    This paper describes the manufacturing, characterization and parametric modeling of a novel fiber-reinforced composite flexible skin with in-plane negative Poisson’s ratio (auxetic) behavior. The elastic mechanical performance of the auxetic skin is evaluated using a three-dimensional analytical model based on the classical laminate theory (CLT) and Sun’s thick laminate theory. Good agreement is observed between in-plane Poisson’s ratios and Young’s moduli of the composite skin obtained by the theoretical model and the experimental results. A parametric analysis carried out with the validated model shows that significant changes in the in-plane negative Poisson’s ratio can be achieved through different combinations of matrix and fiber materials and stacking sequences. It is also possible to identify fiber-reinforced composite skin configurations with the same in-plane auxeticity but different orthotropic stiffness performance, or the same orthotropic stiffness performance but different in-plane auxeticity. The analysis presented in this work provides useful guidelines to develop and manufacture flexible skins with negative Poisson’s ratio for applications focused on morphing aircraft wing designs.

  17. Characterization and Mitigation of Resistive Losses in a Large Area Laser Power Converter

    DTIC Science & Technology

    2014-03-27

    CHARACTERIZATION AND MITIGATION OF RESISTIVE LOSSES IN A LARGE AREA LASER POWER CONVERTER THESIS Eli A. Garduño, Second Lieutenant, USAF AFIT-ENP-14...LOSSES IN A LARGE AREA LASER POWER CONVERTER THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering and...DISTRIBUTION UNLIMITED. AFIT-ENP-14-M-09 CHARACTERIZATION AND MITIGATION OF RESISTIVE LOSSES IN A LARGE AREA LASER POWER CONVERTER Eli A. Garduño, BS

  18. Large amplitude dust-acoustic double layers in non-thermal plasmas with positive and negative dust

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.; Pillay, S. R.

    2011-11-29

    The existence of large amplitude double layers in a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons is investigated using the Sagdeev pseudopotential technique. Both positive potential and negative potential double layers are found to be supported by the model. The variation of the maximum amplitudes of the double layers and corresponding Mach numbers are examined as a function of various plasma parameters. In particular, we investigate to what extent ion non-thermal effects are required for positive potential double layers to occur.

  19. Large amplitude dust-acoustic double layers in non-thermal plasmas with positive and negative dust

    NASA Astrophysics Data System (ADS)

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.

    2011-11-01

    The existence of large amplitude double layers in a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons is investigated using the Sagdeev pseudopotential technique. Both positive potential and negative potential double layers are found to be supported by the model. The variation of the maximum amplitudes of the double layers and corresponding Mach numbers are examined as a function of various plasma parameters. In particular, we investigate to what extent ion non-thermal effects are required for positive potential double layers to occur.

  20. Crop identification and area estimation over large geographic areas using LANDSAT MSS data

    NASA Technical Reports Server (NTRS)

    Bauer, M. E. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. LANDSAT MSS data was adequate to accurately identify wheat in Kansas; corn and soybean estimates in Indiana were less accurate. Computer-aided analysis techniques were effectively used to extract crop identification information from LANDSAT data. Systematic sampling of entire counties made possible by computer classification methods resulted in very precise area estimates at county, district, and state levels. Training statistics were successfully extended from one county to other counties having similar crops and soils if the training areas sampled the total variation of the area to be classified.

  1. Large-scale patterns of turnover and Basal area change in Andean forests.

    PubMed

    Báez, Selene; Malizia, Agustina; Carilla, Julieta; Blundo, Cecilia; Aguilar, Manuel; Aguirre, Nikolay; Aquirre, Zhofre; Álvarez, Esteban; Cuesta, Francisco; Duque, Álvaro; Farfán-Ríos, William; García-Cabrera, Karina; Grau, Ricardo; Homeier, Jürgen; Linares-Palomino, Reynaldo; Malizia, Lucio R; Cruz, Omar Melo; Osinaga, Oriana; Phillips, Oliver L; Reynel, Carlos; Silman, Miles R; Feeley, Kenneth J

    2015-01-01

    General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.

  2. Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

    PubMed Central

    Blundo, Cecilia; Aguilar, Manuel; Aguirre, Nikolay; Aquirre, Zhofre; Álvarez, Esteban; Cuesta, Francisco; Farfán-Ríos, William; García-Cabrera, Karina; Grau, Ricardo; Linares-Palomino, Reynaldo; Malizia, Lucio R.; Cruz, Omar Melo; Osinaga, Oriana; Reynel, Carlos; Silman, Miles R.

    2015-01-01

    General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century. PMID:25973977

  3. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  4. Large-scale optimization-based non-negative computational framework for diffusion equations: Parallel implementation and performance studies

    DOE PAGES

    Chang, Justin; Karra, Satish; Nakshatrala, Kalyana B.

    2016-07-26

    It is well-known that the standard Galerkin formulation, which is often the formulation of choice under the finite element method for solving self-adjoint diffusion equations, does not meet maximum principles and the non-negative constraint for anisotropic diffusion equations. Recently, optimization-based methodologies that satisfy maximum principles and the non-negative constraint for steady-state and transient diffusion-type equations have been proposed. To date, these methodologies have been tested only on small-scale academic problems. The purpose of this paper is to systematically study the performance of the non-negative methodology in the context of high performance computing (HPC). PETSc and TAO libraries are, respectively, usedmore » for the parallel environment and optimization solvers. For large-scale problems, it is important for computational scientists to understand the computational performance of current algorithms available in these scientific libraries. The numerical experiments are conducted on the state-of-the-art HPC systems, and a single-core performance model is used to better characterize the efficiency of the solvers. Furthermore, our studies indicate that the proposed non-negative computational framework for diffusion-type equations exhibits excellent strong scaling for real-world large-scale problems.« less

  5. Large-scale optimization-based non-negative computational framework for diffusion equations: Parallel implementation and performance studies

    SciTech Connect

    Chang, Justin; Karra, Satish; Nakshatrala, Kalyana B.

    2016-07-26

    It is well-known that the standard Galerkin formulation, which is often the formulation of choice under the finite element method for solving self-adjoint diffusion equations, does not meet maximum principles and the non-negative constraint for anisotropic diffusion equations. Recently, optimization-based methodologies that satisfy maximum principles and the non-negative constraint for steady-state and transient diffusion-type equations have been proposed. To date, these methodologies have been tested only on small-scale academic problems. The purpose of this paper is to systematically study the performance of the non-negative methodology in the context of high performance computing (HPC). PETSc and TAO libraries are, respectively, used for the parallel environment and optimization solvers. For large-scale problems, it is important for computational scientists to understand the computational performance of current algorithms available in these scientific libraries. The numerical experiments are conducted on the state-of-the-art HPC systems, and a single-core performance model is used to better characterize the efficiency of the solvers. Furthermore, our studies indicate that the proposed non-negative computational framework for diffusion-type equations exhibits excellent strong scaling for real-world large-scale problems.

  6. Quantum transport in strongly disordered crystals: Electrical conductivity with large negative vertex corrections

    NASA Astrophysics Data System (ADS)

    Janiš, Václav; Pokorný, Vladislav

    2012-12-01

    We propose a renormalization scheme of the Kubo formula for the electrical conductivity with multiple backscatterings contributing to the electron-hole irreducible vertex derived from the asymptotic limit to high spatial dimensions. We use this vertex to represent the two-particle Green function via a symmetrized Bethe-Salpeter equation in momentum space. We further utilize the dominance of a pole in the irreducible vertex to an approximate diagonalization of the Bethe-Salpeter equation and a non-perturbative representation of the electron-hole correlation function. The latter function is then used to derive a compact representation for the electrical conductivity at zero temperature without the necessity to evaluate separately the Drude term and vertex corrections. The electrical conductivity calculated in this way remains nonnegative also in the strongly disordered regime where the localization effects become significant and the negative vertex corrections in the standard Kubo formula overweight the Drude term.

  7. Negative-Pressure Wound Therapy: A Hemostatic Adjunct for Control of Coagulopathic Hemorrhage in Large Soft Tissue Wounds

    DTIC Science & Technology

    2012-01-01

    such as large soft tissue injuries, high-energy pene- trating trauma and open fractures have also been reported.6Y10 NPWT has been used for evacuating...injuries associated with high-energy open tibial shaft fractures . J Orthop Trauma. 2007;21:11 17. 10. Stannard JP, Robinson JT, Anderson ER, et al...Negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma. J Trauma. 2006;60;1301 1306. 11. Kakagia D

  8. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics

    SciTech Connect

    Milnes, J. S. Conneely, T. M.; Howorth, J.; Horsfield, C. J.

    2014-11-15

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

  9. Negative blood oxygenation level dependent homunculus and somatotopic information in primary motor cortex and supplementary motor area.

    PubMed

    Zeharia, Noa; Hertz, Uri; Flash, Tamar; Amedi, Amir

    2012-11-06

    A crucial attribute in movement encoding is an adequate balance between suppression of unwanted muscles and activation of required ones. We studied movement encoding across the primary motor cortex (M1) and supplementary motor area (SMA) by inspecting the positive and negative blood oxygenation level-dependent (BOLD) signals in these regions. Using periodic and event-related experiments incorporating the bilateral/axial movements of 20 body parts, we report detailed mototopic imaging maps in M1 and SMA. These maps were obtained using phase-locked analysis. In addition to the positive BOLD, significant negative BOLD was detected in M1 but not in the SMA. The negative BOLD spatial pattern was neither located at the ipsilateral somatotopic location nor randomly distributed. Rather, it was organized somatotopically across the entire homunculus and inversely to the positive BOLD, creating a negative BOLD homunculus. The neuronal source of negative BOLD is unclear. M1 provides a unique system to test whether the origin of negative BOLD is neuronal, because different arteries supply blood to different regions in the homunculus, ruling out blood-stealing explanations. Finally, multivoxel pattern analysis showed that positive BOLD in M1 and SMA and negative BOLD in M1 contain somatotopic information, enabling prediction of the moving body part from inside and outside its somatotopic location. We suggest that the neuronal processes underlying negative BOLD participate in somatotopic encoding in M1 but not in the SMA. This dissociation may emerge because of differences in the activity of these motor areas associated with movement suppression.

  10. A nonlinear negative stiffness metamaterial unit cell and small-on-large multiscale material model

    NASA Astrophysics Data System (ADS)

    Klatt, Timothy; Haberman, Michael R.

    2013-07-01

    A persistent challenge in the design of composite materials is the ability to fabricate materials that simultaneously display high stiffness and high loss factors for the creation of structural elements capable of passively suppressing vibro-acoustic energy. Relevant recent research has shown that it is possible to produce composite materials whose macroscopic mechanical stiffness and loss properties surpass those of conventional composites through the addition of trace amounts of materials displaying negative stiffness (NS) induced by phase transformation [R. S. Lakes et al., Nature 410, 565-567 (2001)]. The present work investigates the ability to elicit NS behavior without employing physical phenomena such as inherent nonlinear material behavior (e.g., phase change or plastic deformation) or dynamic effects, but rather the controlled buckling of small-scale structural elements, metamaterials, embedded in a continuous viscoelastic matrix. To illustrate the effect of these buckled elements, a nonlinear hierarchical multiscale material model is derived, which estimates the macroscopic stiffness and loss of a composite material containing pre-strained microscale structured inclusions. The multiscale model consists of two scale transition models, the first being an energy-based nonlinear finite element (FE) method to determine the tangent modulus of the metamaterial unit cell, and the other a classical analytical micromechanical model to determine the effective stiffness and loss tensors of a heterogeneous material for small perturbations from the local strain state of the unit cells. The FE method enables the estimation of an effective nonlinear anisotropic stiffness tensor of a buckled microstructure that produces NS and is sufficiently general to consider geometries different from those given in this work.

  11. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer.

    PubMed

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-12

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  12. Uniform H(-) ion beam extraction in a large negative ion source with a tent-shaped magnetic filter.

    PubMed

    Tobari, H; Hanada, M; Kashiwagi, M; Taniguchi, M; Umeda, N; Watanabe, K; Inoue, T; Sakamoto, K; Takado, N

    2008-02-01

    Based on previous studies on the spatial uniformity of the negative ion beam, the external magnetic filter was replaced to a novel tent-shaped magnetic filter in the JAEA 10 A negative ion source. The line-cusp field configuration on the source chamber was also changed to form a symmetric magnetic field like many of positive ion sources aiming at high proton yield. This magnetic field configuration allows fast electrons emitted from filament cathodes to rotate azimuthally inside the source chamber. The source configuration thus prevents localization of fast electrons due to their B x grad B drift in the filter field. As a result, the H(-) ion beam profile extracted from a wide region of 340 x 170 mm(2) showed reduction of standard deviation from 16% in the original to 7.9% with the tent filter. The negative ion source with the tent filter satisfied the requirement of the beam uniformity for a large negative ion source in the ITER neutral beam injection.

  13. Nonzero-temperature entanglement negativity of quantum spin models: Area law, linked cluster expansions, and sudden death.

    PubMed

    Sherman, Nicholas E; Devakul, Trithep; Hastings, Matthew B; Singh, Rajiv R P

    2016-02-01

    We show that the bipartite logarithmic entanglement negativity (EN) of quantum spin models obeys an area law at all nonzero temperatures. We develop numerical linked cluster (NLC) expansions for the "area-law" logarithmic entanglement negativity as a function of temperature and other parameters. For one-dimensional models the results of NLC are compared with exact diagonalization on finite systems and are found to agree very well. The NLC results are also obtained for two dimensional XXZ and transverse field Ising models. In all cases, we find a sudden onset (or sudden death) of negativity at a finite temperature above which the negativity is zero. We use perturbation theory to develop a physical picture for this sudden onset (or sudden death). The onset of EN or its magnitude are insensitive to classical finite-temperature phase transitions, supporting the argument for absence of any role of quantum mechanics at such transitions. On approach to a quantum critical point at T=0, negativity shows critical scaling in size and temperature.

  14. Nonzero-temperature entanglement negativity of quantum spin models: Area law, linked cluster expansions, and sudden death

    NASA Astrophysics Data System (ADS)

    Sherman, Nicholas E.; Devakul, Trithep; Hastings, Matthew B.; Singh, Rajiv R. P.

    2016-02-01

    We show that the bipartite logarithmic entanglement negativity (EN) of quantum spin models obeys an area law at all nonzero temperatures. We develop numerical linked cluster (NLC) expansions for the "area-law" logarithmic entanglement negativity as a function of temperature and other parameters. For one-dimensional models the results of NLC are compared with exact diagonalization on finite systems and are found to agree very well. The NLC results are also obtained for two dimensional X X Z and transverse field Ising models. In all cases, we find a sudden onset (or sudden death) of negativity at a finite temperature above which the negativity is zero. We use perturbation theory to develop a physical picture for this sudden onset (or sudden death). The onset of EN or its magnitude are insensitive to classical finite-temperature phase transitions, supporting the argument for absence of any role of quantum mechanics at such transitions. On approach to a quantum critical point at T =0 , negativity shows critical scaling in size and temperature.

  15. Graphene-based large area dye-sensitized solar cell modules.

    PubMed

    Casaluci, Simone; Gemmi, Mauro; Pellegrini, Vittorio; Di Carlo, Aldo; Bonaccorso, Francesco

    2016-03-07

    We demonstrate spray coating of graphene ink as a viable method for large-area fabrication of graphene-based dye-sensitized solar cell (DSSC) modules. A graphene-based ink produced by liquid phase exfoliation of graphite is spray coated onto a transparent conductive oxide substrate to realize a large area (>90 cm(2)) semi-transparent (transmittance 44%) counter-electrode (CE) replacing platinum, the standard CE material. The graphene-based CE is successfully integrated in a large-area (43.2 cm(2) active area) DSSC module achieving a power conversion efficiency of 3.5%. The approach demonstrated here paves the way to all-printed, flexible, and transparent graphene-based large-area and cost-effective photovoltaic devices on arbitrary substrates.

  16. Large area substrate for surface enhanced Raman spectroscopy (SERS) using glass-drawing technique

    DOEpatents

    Ivanov, Ilia N; Simpson, John T

    2012-06-26

    A method of making a large area substrate comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes. Each cut drawn tube has a first end and a second end along the longitudinal direction of the respective cut drawn tube. The cut drawn tubes collectively have a predetermined periodicity. The method of making a large area substrate also comprises forming a metal layer on the first ends of the cut drawn tubes to provide a large area substrate.

  17. Approach to the Triple Negative Breast Cancer in New Drugs Area.

    PubMed

    Mirzania, Mehrzad

    2016-04-01

    Triple negative breast cancers (TNBCs) are associated with aggressive course, higher rates of visceral and central nervous system metastases and lower survival rate than hormone receptor positive. Once metastasis has occurred, a median survival was approximately one year. Currently, chemotherapy in TNBC is similar to other HER2- negative breast cancers but in the near future, it will revolutionize. TNBCs are quite heterogeneous based on biomarkers and genetic variations. The series of new drugs have been tried; in this article, platinum, anti-epigenetic drugs, PARP inhibitors, epidermal growth factor receptor inhibitor, Src family kinase inhibitor, anti androgen, glycoprotein Non-metastatic melanoma B (gpNMB) antibody, LHRH conjugated to cytotoxic drugs and inhibition of the PI3K/AKT/mTOR pathway will be explained. What is the optimal therapy for TNBC patients? It is still not clear but it seems that the road map according to biological and genetic markers is taking shape.

  18. Aetiology of PCR negative suspected Crimean-Congo hemorrhagic fever cases in an endemic area

    PubMed Central

    Sunbul, Mustafa; Fletcher, Tom E.

    2016-01-01

    Crimean–Congo hemorrhagic fever (CCHF) is a potentially fatal tick-borne viral infection that is widely distributed worldwide. The diagnosis is frequently missed due to the non-specific initial symptoms and the differential diagnosis included many infectious and non-infectious causes. This retrospective study describes the clinical features and final diagnoses of 116 suspect CCHF cases that were admitted to a tertiary CCHF center in Turkey, and were CCHF IgM and PCR negative. PMID:27677379

  19. Aetiology of PCR negative suspected Crimean-Congo hemorrhagic fever cases in an endemic area.

    PubMed

    Tanyel, Esra; Sunbul, Mustafa; Fletcher, Tom E; Leblebicioglu, Hakan

    2016-01-01

    Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal tick-borne viral infection that is widely distributed worldwide. The diagnosis is frequently missed due to the non-specific initial symptoms and the differential diagnosis included many infectious and non-infectious causes. This retrospective study describes the clinical features and final diagnoses of 116 suspect CCHF cases that were admitted to a tertiary CCHF center in Turkey, and were CCHF IgM and PCR negative.

  20. A novel photovoltaic power system which uses a large area concentrator mirror

    NASA Technical Reports Server (NTRS)

    Arrison, Anne; Fatemi, Navid

    1987-01-01

    A preliminary analysis has been made of a novel photovoltaic power system concept. The system is composed of a small area, dense photovoltaic array, a large area solar concentrator, and a battery system for energy storage. The feasibility of such a system is assessed for space power applications. The orbital efficiency, specific power, mass, and area of the system are calculated under various conditions and compared with those for the organic Rankine cycle solar dynamic system proposed for Space Station. Near term and advanced large area concentrator photovoltaic systems not only compare favorably to solar dynamic systems in terms of performance but offer other benefits as well.

  1. Sub-100 nm Gold Nanomatryoshkas Improve Photo-thermal Therapy Efficacy in Large and Highly Aggressive Triple Negative Breast Tumors

    PubMed Central

    Bishnoi, Sandra; Urban, Alexander; Charron, Heather; Mitchell, Tamika; Shea, Martin; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi; Joshi, Amit

    2014-01-01

    There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or nectrotic regions. We report the performance advantages obtained by sub 100 nm gold nanomatryushkas, comprising of concentric gold-silica-gold layers compared to conventional ~150 nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000 mm3) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5X accumulation within large tumors results in superior therapy efficacy. PMID:25051221

  2. The negative binomial-Lindley distribution as a tool for analyzing crash data characterized by a large amount of zeros.

    PubMed

    Lord, Dominique; Geedipally, Srinivas Reddy

    2011-09-01

    The modeling of crash count data is a very important topic in highway safety. As documented in the literature, given the characteristics associated with crash data, transportation safety analysts have proposed a significant number of analysis tools, statistical methods and models for analyzing such data. Among the data issues, we find the one related to crash data which have a large amount of zeros and a long or heavy tail. It has been found that using this kind of dataset could lead to erroneous results or conclusions if the wrong statistical tools or methods are used. Thus, the purpose of this paper is to introduce a new distribution, known as the negative binomial-Lindley (NB-L), which has very recently been introduced for analyzing data characterized by a large number of zeros. The NB-L offers the advantage of being able to handle this kind of datasets, while still maintaining similar characteristics as the traditional negative binomial (NB). In other words, the NB-L is a two-parameter distribution and the long-term mean is never equal to zero. To examine this distribution, simulated and observed data were used. The results show that the NB-L can provide a better statistical fit than the traditional NB for datasets that contain a large amount of zeros.

  3. Sub-100nm gold nanomatryoshkas improve photo-thermal therapy efficacy in large and highly aggressive triple negative breast tumors.

    PubMed

    Ayala-Orozco, Ciceron; Urban, Cordula; Bishnoi, Sandra; Urban, Alexander; Charron, Heather; Mitchell, Tamika; Shea, Martin; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi; Joshi, Amit

    2014-10-10

    There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or necrotic regions. We report the performance advantages obtained by sub 100nm gold nanomatryushkas, comprising concentric gold-silica-gold layers compared to conventional ~150nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000mm(3)) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5× accumulation within large tumors results in superior therapy efficacy.

  4. Large and negative Goos-Hänchen shift near the Brewster dip on reflection from weakly absorbing media.

    PubMed

    Lai, H M; Chan, S W

    2002-05-01

    Applying Artmann's formula to a light beam in the TM state of wave polarization, we show analytically the existence of a large and negative Goos-Hänchen shift near the angle of the Brewster dip on reflection from a weakly absorbing semi-infinite medium. The shift is opposite that in the case of total internal reflection, and it can be an order of magnitude larger than a wavelength if the absorption of the reflecting medium is sufficiently weak. Examples are given, and the detectibility of the shift is discussed.

  5. Addendum to “Large negative Goos Hanchen shift at metal surfaces”, [Opt. Comm. 276 (2007) 206

    NASA Astrophysics Data System (ADS)

    Leung, P. T.; Chen, C. W.; Chiang, H.-P.

    2008-03-01

    In the above communication, we have investigated in details the possibility of observing a large negative lateral Goos-Hanchen (GH) shift from p-polarized light at long wavelength incident onto a bare metal surface, at angles close to grazing incidence. The shift could be up to a few wavelength (e.g. ∼20 μm at a wavelength of 3390 nm onto silver) and the possible presence of a "pseudo Brewster angle" will not hinder the observability of such an effect. This effect has since been verified experimentally via reflection of IR light from a gold surface [1].

  6. Large and negative Goos-Hanchen shift near the Brewster dip on reflection from weakly absorbing media

    NASA Astrophysics Data System (ADS)

    Lai, H. M.; Chan, S. W.

    2002-05-01

    Applying Artmann's formula to a light beam in the TM state of wave polarization, we show analytically the existence of a large and negative Goos-Hanchen shift near the angle of the Brewster dip on reflection from a weakly absorbing semi-infinite medium. The shift is opposite that in the case of total internal reflection, and it can be an order of magnitude larger than a wavelength if the absorption of the reflecting medium is sufficiently weak. Examples are given, and the detectibility of the shift is discussed.

  7. MUTAGENIC CHARACTERISTICS OF RIVER WATERS FLOWING THROUGH LARGE METROPOLITAN AREAS IN NORTH AMERICA

    EPA Science Inventory

    Mutagenic characteristics of river waters flowing through large metropolitan areas in North America

    The hanging technique using blue rayon, which specifically adsorbs mutagens with multicyclic planar structures, has the advantages over most conventional methods of not havi...

  8. Large area crop inventory experiment crop assessment subsystem software requirements document

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The functional data processing requirements are described for the Crop Assessment Subsystem of the Large Area Crop Inventory Experiment. These requirements are used as a guide for software development and implementation.

  9. Gold-film coating assisted femtosecond laser fabrication of large-area, uniform periodic surface structures.

    PubMed

    Feng, Pin; Jiang, Lan; Li, Xin; Rong, Wenlong; Zhang, Kaihu; Cao, Qiang

    2015-02-20

    A simple, repeatable approach is proposed to fabricate large-area, uniform periodic surface structures by a femtosecond laser. 20 nm gold films are coated on semiconductor surfaces on which large-area, uniform structures are fabricated. In the case study of silicon, cross-links and broken structures of laser induced periodic surface structures (LIPSSs) are significantly reduced on Au-coated silicon. The good consistency between the scanning lines facilitates the formation of large-area, uniform LIPSSs. The diffusion of hot electrons in the Au films increases the interfacial carrier densities, which significantly enhances interfacial electron-phonon coupling. High and uniform electron density suppresses the influence of defects on the silicon and further makes the coupling field more uniform and thus reduces the impact of laser energy fluctuations, which homogenizes and stabilizes large-area LIPSSs.

  10. Synthesis of Few-Layer, Large Area Hexagonal-Boron Nitride by Pulsed Laser Deposition (POSTPRINT)

    DTIC Science & Technology

    2014-09-01

    AFRL-RX-WP-JA-2015-0050 SYNTHESIS OF FEW-LAYER, LARGE AREA HEXAGONAL-BORON NITRIDE BY PULSED LASER DEPOSITION (POSTPRINT) Nicholas R Glavin...2014 4. TITLE AND SUBTITLE SYNTHESIS OF FEW-LAYER, LARGE AREA HEXAGONAL- BORON NITRIDE BY PULSED LASER DEPOSITION (POSTPRINT) 5a. CONTRACT NUMBER...deposition (PLD) has been investigated as a technique for synthesis of ultra-thin, few-layer hexagonal boron nitride (ɦ-BN) thin films on crystalline

  11. Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

    DTIC Science & Technology

    2012-01-10

    blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma - ray Space Telescope have been observed contemporaneously by the Very Long...galaxies: jets – galaxies: nuclei – gamma rays : galaxies – radio continuum: galaxies 1. INTRODUCTION The Large Area Telescope (LAT; Atwood et al. 2009...on board the Fermi Gamma - ray Space Telescope is a wide-field telescope covering the energy range from about 20 MeV to more than 300 GeV. It has been

  12. Combining large area fluorescence with multiphoton microscopy for improved detection of oral epithelial neoplasia (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pal, Rahul; Yang, Jinping; Qiu, Suimin; McCammon, Susan; Resto, Vicente; Vargas, Gracie

    2016-03-01

    Volumetric Multiphoton Autofluorescence Microscopy (MPAM) and Second Harmonic Generation Microscopy (SHGM) show promise for revealing indicators of neoplasia representing the complex microstructural organization of mucosa, potentially providing high specificity for detection of neoplasia, but is limited by small imaging area. Large area fluorescence methods on the other hand show high sensitivity appropriate for screening but are hampered by low specificity. In this study, we apply MPAM-SHGM following guidance from large area fluorescence, by either autofluorescence or a targeted metabolic fluorophore, as a potentially clinically viable approach for detection of oral neoplasia. Sites of high neoplastic potentially were identified by large area red/green autofluorescence or by a fluorescently labelled deoxy-glucose analog, 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG) to highlight areas of high glucose uptake across the buccal pouch of a hamster model for OSCC. Follow-up MPAM-SHGM was conducted on regions of interests (ROIs) to assess whether microscopy would reveal microscopic features associated with neoplasia to confirm or exclude large area fluorescence findings. Parameters for analysis included cytologic metrics, 3D epithelial connective tissue interface metrics (MPAM-SHGM) and intensity of fluorescence (widefield). Imaged sites were biopsied and processed for histology and graded by a pathologist. A small sample of human ex vivo tissues were also imaged. A generalized linear model combining image metrics from large area fluorescence and volumetric MPAM-SHGM indicated the ability to delineate normal and inflammation from neoplasia.

  13. Detecting Change in Landscape Greenness over Large Areas: An Example for New Mexico, USA

    EPA Science Inventory

    Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can potentially detect large-scale, slow changes (e.g., climate change), as well as more local and rapid changes (e.g., fire, land development). A useful indicator for detecting change i...

  14. Few-mode and large-mode-area fiber with circularly distributed cores

    NASA Astrophysics Data System (ADS)

    Jin, Wenxing; Ren, Guobin; Jiang, Youchao; Wu, Yue; Xu, Yao; Yang, Yuguang; Shen, Ya; Ren, Wenhua; Jian, Shuisheng

    2017-03-01

    In this paper, a novel few-mode large-mode-area fiber is proposed. This type of fiber consists of 11 conventional cores and 8 air-hole cores circularly arranged around the center core. Few-mode condition equal to strict dual-mode here is available by appropriate adjusting on corepitch, relative refractive index difference and core radius. Large effective area of fundamental mode around 1403.561 μm2 could be achieved by optimization of structural parameters. Bending loss less than 10-3 dB / m is realized when effective area is over 1400 μm2.

  15. Large-scale synthesis of high-quality hexagonal boron nitride nanosheets for large-area graphene electronics.

    PubMed

    Lee, Kang Hyuck; Shin, Hyeon-Jin; Lee, Jinyeong; Lee, In-yeal; Kim, Gil-Ho; Choi, Jae-Young; Kim, Sang-Woo

    2012-02-08

    Hexagonal boron nitride (h-BN) has received a great deal of attention as a substrate material for high-performance graphene electronics because it has an atomically smooth surface, lattice constant similar to that of graphene, large optical phonon modes, and a large electrical band gap. Herein, we report the large-scale synthesis of high-quality h-BN nanosheets in a chemical vapor deposition (CVD) process by controlling the surface morphologies of the copper (Cu) catalysts. It was found that morphology control of the Cu foil is much critical for the formation of the pure h-BN nanosheets as well as the improvement of their crystallinity. For the first time, we demonstrate the performance enhancement of CVD-based graphene devices with large-scale h-BN nanosheets. The mobility of the graphene device on the h-BN nanosheets was increased 3 times compared to that without the h-BN nanosheets. The on-off ratio of the drain current is 2 times higher than that of the graphene device without h-BN. This work suggests that high-quality h-BN nanosheets based on CVD are very promising for high-performance large-area graphene electronics.

  16. Selectively filled large-mode-area photonic crystal fiber for high power applications

    NASA Astrophysics Data System (ADS)

    Saini, Than S.; Kumar, Ajeet; Rastogi, Vipul; Sinha, Ravindra K.

    2013-09-01

    A large-mode-area (LMA) single-mode (SM) photonic crystal fiber (PCF) structure for applications in high power fiber lasers, amplifiers and sensors is proposed. In the proposed structure the center air hole has been removed to form the core and the six elliptical air holes of inner ring around the center core have been selectively filled with high refractive index material. Effects of design parameters on SM operation and mode area are numerically investigated by using the full vectorial finite-element method. Structure offers large-mode-area exceeding 835 μm2 at 1.064 μm wavelength. A PCF with such a large-mode-area would significantly reduce the nonlinear effects and would be useful for high power applications.

  17. Large area pixel detector WIDEPIX with full area sensitivity composed of 100 Timepix assemblies with edgeless sensors

    NASA Astrophysics Data System (ADS)

    Jakubek, J.; Jakubek, M.; Platkevic, M.; Soukup, P.; Turecek, D.; Sykora, V.; Vavrik, D.

    2014-04-01

    The superior properties of the single particle counting semiconductor pixel detectors in radiation imaging are well known. They are namely: very high dynamic range due to digital counting, absence of integration and read-out noise, high spatial resolution and energy sensitivity. The major disadvantage of current pixel devices preventing their broad exploitation has been their relatively small sensitive area of few cm2. This disadvantage is often solved using tiling method placing many detector units side by side forming a large matrix. The current tiling techniques require rather large gaps of few millimeters between tiles. These gaps stand as areas insensitive to radiation which is acceptable only in some applications such as diffraction imaging. However standard transmission radiography requires fully continuous area sensitivity. In this article we present the new large area device WIDEPIX composed of a matrix of 10 × 10 tiles of silicon pixel detectors Timepix (each of 256 × 256 pixels with pitch of 55 μm) having fully sensitive area of 14.3 × 14.3 cm2 without any gaps between the tiles. The device contains a total of 6.5 mega pixels. This achievement was reached thanks to new technology of edgeless semiconductor sensors together with precise alignment technique and multilevel architecture of readout electronics. The mechanical construction of the device is fully modular and scalable. This concept allows replacing any single detector tile which significantly improves production yield. The first results in the field of X-ray radiography and material sensitive X-ray radiography are presented in this article.

  18. Helicobacter pylori-negative gastric cancer: advanced-stage undifferentiated adenocarcinoma located in the pyloric gland area.

    PubMed

    Okano, Akihiro; Kato, Shigeru; Ohana, Masaya

    2017-02-01

    The incidence of Helicobacter pylori-negative gastric cancer (HpNGC) is extremely low. A 78-year old female without H. pylori infection was diagnosed with type 4 advanced-stage gastric prepylorus cancer. Distal gastrectomy was performed as for HpNGC (cT3N0M0). Histological findings of the resected specimen showed poorly differentiated adenocarcinoma and signet ring cell carcinoma, which were located in the pyloric gland area, diffusely invaded beyond the serosa without lymph node metastasis (pT4aN0M0). Most cases of undifferentiated-type HpNGC are diagnosed in the early stage and are located in the fundic gland area. We report the first case of advanced-stage undifferentiated HpNGC located in the pyloric gland area.

  19. Simple room-temperature preparation of high-yield large-area graphene oxide.

    PubMed

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

  20. Large area projection liquid-crystal video display system with inherent grid pattern optically removed

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang (Inventor)

    1992-01-01

    A relatively small and low-cost system is provided for projecting a large and bright television image onto a screen. A miniature liquid crystal array is driven by video circuitry to produce a pattern of transparencies in the array corresponding to a television image. Light is directed against the rear surface of the array to illuminate it, while a projection lens lies in front of the array to project the image of the array onto a large screen. Grid lines in the liquid crystal array are eliminated by a spacial filter which comprises a negative of the Fourier transform of the grid.

  1. The Scale of Positive and Negative Experience (SPANE): Psychometric Properties and Normative Data in a Large Chinese Sample

    PubMed Central

    Li, Feng; Bai, Xinwen; Wang, Yong

    2013-01-01

    Background The Scale of Positive and Negative Experience (SPANE) is a new instrument that assesses subjective feelings of well-being and ill-being and overcome several limitations of previous popular instruments. The current study examined the scale's psychometric properties with a large Chinese sample. Principal Findings Data were collected form 21,322 full-time workers from the power industry. The psychometric properties were assessed in term of internal consistency reliability, factorial validity, convergent validity, and measurement invariance across gender, age, marital status, education level, and income level. The results demonstrate that the SPANE has high internal consistency reliability, a correlated two-factor structure (with the uniqueness of three general and specific items of positive and negative feelings allowed to correlate with each other), strict equivalence across gender, age and marital status, and strong equivalence across education and income. Furthermore, the SPANE converges well with two measures of life satisfaction. Conclusion The Chinese version of the SPANE behaves consistently with the original and can be used in future studies of emotional well-being. The scale norms are presented in terms of percentile rankings, and implications and directions for future research are discussed. PMID:23573297

  2. Negative pressure of the environmental air in the cleaning area of the materials and sterilization center: a systematic review

    PubMed Central

    Ciofi-Silva, Caroline Lopes; Hansen, Lisbeth Lima; Almeida, Alda Graciele Claudio dos Santos; Kawagoe, Julia Yaeko; Padoveze, Maria Clara; Graziano, Kazuko Uchikawa

    2016-01-01

    ABSTRACT Objective: to analyze the scientific evidence on aerosols generated during cleaning activities of health products in the Central Service Department (CSD) and the impact of the negative pressure of the ambient air in the cleaning area to control the dispersion of aerosols to adjacent areas. Method: for this literature systematic review the following searches were done: search guidelines, manuals or national and international technical standards given by experts; search in the portal and databases PubMed, Scopus, CINAHL and Web of Science; and a manual search of scientific articles. Results: the five technical documents reviewed recommend that the CSD cleaning area should have a negative differential ambient air pressure, but scientific articles on the impact of this intervention were not found. The four articles included talked about aerosols formed after the use of a ultrasonic cleaner (an increased in the contamination especially during use) and pressurized water jet (formation of smaller aerosols 5μm). In a study, the aerosols formed from contaminated the hot tap water with Legionella pneumophila were evaluated. Conclusions: there is evidence of aerosol formation during cleanup activities in CSD. Studies on occupational diseases of respiratory origin of workers who work in CSD should be performed. PMID:27598374

  3. Oxygen Level and LFP in Task-Positive and Task-Negative Areas: Bridging BOLD fMRI and Electrophysiology.

    PubMed

    Bentley, William J; Li, Jingfeng M; Snyder, Abraham Z; Raichle, Marcus E; Snyder, Lawrence H

    2016-01-01

    The human default mode network (DMN) shows decreased blood oxygen level dependent (BOLD) signals in response to a wide range of attention-demanding tasks. Our understanding of the specifics regarding the neural activity underlying these "task-negative" BOLD responses remains incomplete. We paired oxygen polarography, an electrode-based oxygen measurement technique, with standard electrophysiological recording to assess the relationship of oxygen and neural activity in task-negative posterior cingulate cortex (PCC), a hub of the DMN, and visually responsive task-positive area V3 in the awake macaque. In response to engaging visual stimulation, oxygen, LFP power, and multi-unit activity in PCC showed transient activation followed by sustained suppression. In V3, oxygen, LFP power, and multi-unit activity showed an initial phasic response to the stimulus followed by sustained activation. Oxygen responses were correlated with LFP power in both areas, although the apparent hemodynamic coupling between oxygen level and electrophysiology differed across areas. Our results suggest that oxygen responses reflect changes in LFP power and multi-unit activity and that either the coupling of neural activity to blood flow and metabolism differs between PCC and V3 or computing a linear transformation from a single LFP band to oxygen level does not capture the true physiological process.

  4. Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

    NASA Astrophysics Data System (ADS)

    Guittienne, Ph; Jacquier, R.; Howling, A. A.; Furno, I.

    2017-03-01

    A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmission line coupled to the plasma. This electromagnetic treatment includes mutual inductive coupling using the complex image method, and capacitive matrix coupling between all elements of the resonant network and the plasma. The model reproduces antenna input impedance measurements, with and without plasma, on a 1.2× 1.2 m2 antenna used for large area plasma processing. Analytic expressions are given, and results are obtained by computation of the matrix solution. This method could be used to design planar inductive sources in general, by applying the termination impedances appropriate to each antenna type.

  5. Large-Area Chemical and Biological Decontamination Using a High Energy Arc Lamp (HEAL) System.

    SciTech Connect

    Duty, Chad E; Smith, Rob R; Vass, Arpad Alexander; Ilgner, Ralph H; Brown, Gilbert M

    2008-01-01

    Methods for quickly decontaminating large areas exposed to chemical and biological (CB) warfare agents can present significant logistical, manpower, and waste management challenges. Oak Ridge National Laboratory (ORNL) is pursuing an alternate method to decompose CB agents without the use of toxic chemicals or other potentially harmful substances. This process uses a high energy arc lamp (HEAL) system to photochemically decompose CB agents over large areas (12 m2). Preliminary tests indicate that more than 5 decades (99.999%) of an Anthrax spore simulant (Bacillus globigii) were killed in less than 7 seconds of exposure to the HEAL system. When combined with a catalyst material (TiO2) the HEAL system was also effective against a chemical agent simulant, diisopropyl methyl phosphonate (DIMP). These results demonstrate the feasibility of a rapid, large-area chemical and biological decontamination method that does not require toxic or corrosive reagents or generate hazardous wastes.

  6. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    PubMed Central

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-01-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB. PMID:28205615

  7. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-02-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB.

  8. A new large-area 2pi proportional counting system at NIST.

    PubMed

    King, L E; Hutchinson, J M R; Unterweger, M P

    2008-01-01

    A new large-area gas flow multi-wire proportional counter has been developed to replace the large-area counting system that is currently in use at the National Institute of Standards and Technology (NIST) and several Department of Defense counting facilities for calibrating large-area alpha and beta sources. The current systems are over 20 years old and part replacement is very difficult. The new systems have been built using specifications that will improve on the current systems and allow collecting data at pressures up to 0.2MPa. The ability to operate at higher pressures will increase the beta efficiency of the counter and lead to improved precision in the final measured results. Comparison of the results from the old and new systems is presented for both alpha and beta sources.

  9. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1

    PubMed Central

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-01-01

    Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density. DOI: http://dx.doi.org/10.7554/eLife.13424.001 PMID:27549340

  10. Synthesis and characterization of large specific surface area nanostructured amorphous silica materials.

    PubMed

    Marquez-Linares, Francisco; Roque-Malherbe, Rolando M A

    2006-04-01

    Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications.

  11. An Analysis Methodology for the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Morris, Robin D.; Cohen-Tanugi, Johann

    2004-01-01

    The Large Area Telescope (LAT) instrument on the Gamma Ray Large Area Space Telescope (GLAST) has been designed to detect high-energy gamma rays and determine their direction of incidence and energy. We propose a reconstruction algorithm based on recent advances in statistical methodology. This method, alternative to the standard event analysis inherited from high energy collider physics experiments, incorporates more accurately the physical processes occurring in the detector, and makes full use of the statistical information available. It could thus provide a better estimate of the direction and energy of the primary photon.

  12. A novel method for the activity measurement of large-area beta reference sources.

    PubMed

    Stanga, D; De Felice, P; Keightley, J; Capogni, M; Ioan, M R

    2016-03-01

    A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity.

  13. Fast mapping algorithm of lighting spectrum and GPS coordinates for a large area

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Wei; Hsu, Ke-Fang; Hwang, Jung-Min

    2016-09-01

    In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

  14. System and method for interfacing large-area electronics with integrated circuit devices

    DOEpatents

    Verma, Naveen; Glisic, Branko; Sturm, James; Wagner, Sigurd

    2016-07-12

    A system and method for interfacing large-area electronics with integrated circuit devices is provided. The system may be implemented in an electronic device including a large area electronic (LAE) device disposed on a substrate. An integrated circuit IC is disposed on the substrate. A non-contact interface is disposed on the substrate and coupled between the LAE device and the IC. The non-contact interface is configured to provide at least one of a data acquisition path or control path between the LAE device and the IC.

  15. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Poli, Federica; Coscelli, Enrico; Jørgensen, Mette M; Laurila, Marko; Lægsgaard, Jesper; Broeng, Jes

    2012-03-12

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and gain shaping through distributed spectral filtering of amplified spontaneous emission. The fiber properties are ideal for amplification in the long wavelength regime of the Ytterbium gain spectrum above 1100 nm, and red shifting of the maximum gain to 1130 nm is demonstrated.

  16. A Brief Technical History of the Large-Area Picosecond Photodetector (LAPPD) Collaboration

    SciTech Connect

    Adams, B.W.; et al.

    2016-03-06

    The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large-area photodetectors capable of time resolutions measured in pico-seconds, with accompanying sub-millimeter spatial resolution. During the next three and one-half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non-uniformity less than $15\\%$, time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\\&D performed to develop large-area micro-channel plate glass substrates, resistive and secondary-emitting coatings, large-area bialkali photocathodes, and RF-capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low-power 15-GigaSample/sec waveform sampling 6-channel integrated circuit and supported by a two-level modular data acquisition system based on Field-Programmable Gate Arrays for local control, data-sparcification, and triggering. We discuss the formation, organization, and technical successes and short-comings of the Collaboration. The Collaboration ended in December 2012 with a transition from R\\&D to commercialization.

  17. Highly birefringent large mode area photonic crystal fiber-based sensor for interferometry applications

    NASA Astrophysics Data System (ADS)

    Ademgil, Huseyin

    2016-12-01

    In this work, highly birefringent large mode area (LMA) photonic crystal fiber (PCF) structure for interferometric sensor applications is proposed. The effective mode area, birefringence and the sensitivity coefficient of the proposed PCF structure by employing the full vectorial finite element method (FV-FEM) have been thoroughly investigated. The numerical results have shown that proposed structure simultaneously offers high birefringence of order 10-3, adequately LMA and high sensitivity for various liquid analytes by employing the elliptical liquid core holes.

  18. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  19. Development of large area, low-cost, solar cell processing sequence

    NASA Technical Reports Server (NTRS)

    Chitre, S.; Donon, J.

    1981-01-01

    A cost effective process based on state-of-the-art technology has been developed for the production of large-area (55 sq cm and larger) solar cells. The process is capable of providing silicon and polysilicon cell efficiencies in excess of 10% at an overall cost of 12 c/watt in 1980 dollars. The process provides large throughputs and is suitable for complete automation with high yields. Various stages of the process development are discussed.

  20. The Development of Large-Area Micromegas Detectors for the Atlas Upgrade

    NASA Astrophysics Data System (ADS)

    Wotschack, Joerg

    2013-04-01

    The upgrade of the ATLAS detector at the Large Hadron Collider (LHC) at CERN calls for a new generation of muon detectors capable of operating in a flux of collision and background particles approximately ten times larger compared to today's conditions. We report here on the Muon ATLAS MicroMegas Activity (MAMMA) R&D project aimed at the construction of large-area spark-resistant muon chambers using the micromegas technology.

  1. A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

    USGS Publications Warehouse

    Ferraz, G.; Nichols, J.D.; Hines, J.E.; Stouffer, P.C.; Bierregaard, R.O.; Lovejoy, T.E.

    2007-01-01

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  2. A large-scale deforestation experiment: effects of patch area and isolation on Amazon birds.

    PubMed

    Ferraz, Gonçalo; Nichols, James D; Hines, James E; Stouffer, Philip C; Bierregaard, Richard O; Lovejoy, Thomas E

    2007-01-12

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  3. PD-L1 expression in EBV-negative diffuse large B-cell lymphoma: clinicopathologic features and prognostic implications

    PubMed Central

    Xing, Wei; Dresser, Karen; Zhang, Rui; Evens, Andrew M.; Yu, Hongbo; Woda, Bruce A.; Chen, Benjamin J.

    2016-01-01

    Programmed cell death ligand 1 (PD-L1) is a cell surface glycoprotein that regulates the cellular immune response and serves as a targetable immune checkpoint molecule. PD-L1 is expressed on tumor cells and the immune microenvironment of several human malignancies, including a subset of aggressive lymphomas. We sought to investigate further the clinical and pathologic features of EBV-negative diffuse large B-cell lymphoma (DLBCL) cases that express PD-L1. Immunohistochemical staining using an anti-PD-L1 monoclonal antibody was performed on DLBCL cases from 86 patients. These patients received standard chemotherapy treatment and were followed for up to 175 months. Overall, 14 cases (16%) were considered positive for PD-L1 in tumor cells. In comparison with PD-L1 negative cases, PD-L1 positive cases had a higher rate of non-GCB type (71% vs. 30%, P=0.0060), and higher Ann Arbor stage (II-IV) (100% vs. 73%, P=0.0327). No significant differences were seen in the immunohistochemical expression of BCL2, MYC, or Ki67. Patients with tumors expressing PD-L1 demonstrated inferior overall survival (OS) upon long term follow up (P=0.0447). Both age/sex-adjusted and multivariate analyses identified PD-L1 as an independent predictor for OS (P=0.0101 and P=0.0424). There was no significant difference, however, in terms of remission rates after first treatment, relapse rates, and progression free survival between the groups. Identification of DLBCL cases that express PD-L1 may serve to select a subset of patients that could further benefit from targeted immunotherapy. PMID:27527850

  4. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications.

    PubMed

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-09-21

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K(-1)m(-1), down to the ultra-low κ = 0.55 ± 0.10 W K(-1)m(-1) value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials.

  5. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications

    PubMed Central

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-01-01

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K−1m−1, down to the ultra-low κ = 0.55 ± 0.10 W K−1m−1 value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials. PMID:27650202

  6. High-speed energy efficient selective removal of large area copper layer by laser induced delamination

    NASA Astrophysics Data System (ADS)

    Kmetec, Blaž; Kovačič, Drago; Možina, Janez; Podobnik, Boštjan

    2009-07-01

    An indirect laser-induced method for selective removal of large copper areas from a printed circuit board is theoretically and experimentally investigated. The results show that the threshold condition for the process involves phase transition of the epoxy-based substrate resin. Optimal parameters for maximizing process speed are found and discussed.

  7. High power picosecond vortex laser based on a large-mode-area fiber amplifier.

    PubMed

    Tanaka, Yuichi; Okida, Masahito; Miyamoto, Katsuhiko; Omatsu, Takashige

    2009-08-03

    We present the production of picosecond vortex pulses from a stressed large-mode-area fiber amplifier for the first time. 8.5 W picosecond output with a peak power of approximately 12.5 kW was obtained at a pump power of 29 W. 2009 Optical Society of America.

  8. Large Area Synthesis of 1D-MoSe2 Using Molecular Beam Epitaxy.

    PubMed

    Poh, Sock Mui; Tan, Sherman J R; Zhao, Xiaoxu; Chen, Zhongxin; Abdelwahab, Ibrahim; Fu, Deyi; Xu, Hai; Bao, Yang; Zhou, Wu; Loh, Kian Ping

    2017-01-23

    Large area synthesis of 1D-MoSe2 nanoribbons on both insulating and conducting substrates via molecular beam epitaxy is presented. Dimensional controlled growth of 2D, 1D-MoSe2 , and 1D-2D-MoSe2 hybrid heterostructure is achieved by tuning the growth temperature or Mo:Se precursor ratio.

  9. Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

    PubMed Central

    Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

    2010-01-01

    This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted. PMID:27877336

  10. LARGE AREA LAND COVER MAPPING THROUGH SCENE-BASED CLASSIFICATION COMPOSITING

    EPA Science Inventory

    Over the past decade, a number of initiatives have been undertaken to create definitive national and global data sets consisting of precision corrected Landsat MSS and TM scenes. One important application of these data is the derivation of large area land cover products spanning ...

  11. Fluoride glass microstructured optical fiber with large mode area and mid-infrared transmission.

    PubMed

    Ebendorff-Heidepriem, Heike; Foo, Tze-Cheung; Moore, Roger C; Zhang, Wenqi; Li, Yahua; Monro, Tanya M; Hemming, Alexander; Lancaster, David G

    2008-12-01

    We demonstrate the first fluorozirconate microstructured fiber for use in the mid-infrared. The fiber preform was manufactured via extrusion of a 200 g billet through a complex graphite die. The fiber exhibits large mode area of 6,600 microm(2), loss of 3 dB/m at 4 microm and only marginal excess loss relative to a corresponding unstructured fiber.

  12. Uniform, large surface-area polarization by modifying corona-electrodes geometry.

    PubMed

    Tansel, T; Ener Rusen, S; Rusen, A

    2013-01-01

    We report on the uniform, large scale polarization of ferroelectric materials by a newly designed corona charging technique developing nonconventional electrodes geometry. The results of pyroelectric measurements represented the spatial homogeneity of the polarization attained through a surface area of ~25 cm(2).

  13. Si Based Large Area Substrates for HgCdTe Infrared Detectors

    DTIC Science & Technology

    2010-10-06

    compliant substrate, molecular beam epitaxy, silicon substrate Orin W. Holland Amethyst Research Incorporated 720 North Commerce Suite 345 Ardmore, OK...Contractors (DD882) Inventions (DD882) Principal Investigator: Orin W. Holland, Amethyst Research, Inc. Final Report of Project Title: Si Based Large Area...characterization tool. Figure1. Raman shift with crystallographic orientation differences. Principal Investigator: Orin W. Holland, Amethyst

  14. Large-area fabrication of superhydrophobic surfaces for practical applications: an overview.

    PubMed

    Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

    2010-06-01

    This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.

  15. Few-layer, large-area, 2D covalent organic framework semiconductor thin films.

    PubMed

    Feldblyum, Jeremy I; McCreery, Clara H; Andrews, Sean C; Kurosawa, Tadanori; Santos, Elton J G; Duong, Vincent; Fang, Lei; Ayzner, Alexander L; Bao, Zhenan

    2015-09-21

    In this work, we synthesize large-area thin films of a conjugated, imine-based, two-dimensional covalent organic framework at the solution/air interface. Thicknesses between ∼2-200 nm are achieved. Films can be transferred to any desired substrate by lifting from underneath, enabling their use as the semiconducting active layer in field-effect transistors.

  16. Homeless Students and Academic Achievement: Evidence from a Large Urban Area

    ERIC Educational Resources Information Center

    Tobin, Kerri J.

    2016-01-01

    Child homelessness has recently reached levels unprecedented in the United States since the Great Depression. Contemporary research has attempted to isolate the effects of homelessness on education, with mixed results. This study reports results from a study in one large urban area and finds that there is no meaningful difference in achievement…

  17. Independent Peer Evaluation of the Large Area Crop Inventory Experiment (LACIE): The LACIE Symposium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Yield models and crop estimate accuracy are discussed within the Large Area Crop Inventory Experiment. The wheat yield estimates in the United States, Canada, and U.S.S.R. are emphasized. Experimental results design, system implementation, data processing systems, and applications were considered.

  18. Laser interference lithography for large area patterning and the fabrication of functional nanostructures

    NASA Astrophysics Data System (ADS)

    Wathuthanthri, Ishan

    Nature-inspired phenomena such as the "moth eye" and "lotus leaf" effects have gained a lot of interest in recent years due to potential applications in a wide range of scientific and engineering disciplines. To practically achieve a majority of these biomimetic applications it is necessary to fabricate such nano-featured surfaces in a low-cost and high-throughput manner. To this end, this dissertation focuses on developing and using the Interference Lithography (IL) technologies to achieve large-area nanopatterning. IL is a parallel-type nanolithography technique that shares many of the advantages of other parallel-type techniques such as deep-UV photolithography while alleviating a majority of concerns such as cost and complexity. IL relies on the interference of two or more beams of light where the resulting interference fringes are generally recorded on a light sensitive polymeric material such as photoresist. In simple two-beam IL systems, the periodicity of the interference fringes is simply a function of wavelength and the angle of separation of the two beams, while the maximum coverage area is a constrained by the optical path and the exposed area. To this extent, in the design of interferometers for nanopatterning, the challenge remains in designing systems where a simple mechanism exists for varying the angle of separation of the interfering beams and in turn periodicity of the interference fringes while also enabling large-area exposures. To this end, the first half of this dissertation demonstrates three different IL systems (Lloyd-mirror, two-degree-of freedom Lloyd-mirror, and the tunable two-mirror systems) designed and established at Stevens capable of fast tuning of periodicities while also achieving wafer-scale (4") large-area nanopatterning. Using the large-area nanopatterns of photoresist, various pattern transfer techniques have also been investigated where the photoresist film is used as a template layer to transfer the large-area periodic

  19. The anti-coincidence detector for the GLAST large area telescope

    NASA Astrophysics Data System (ADS)

    Moiseev, A. A.; Hartman, R. C.; Ormes, J. F.; Thompson, D. J.; Amato, M. J.; Johnson, T. E.; Segal, K. N.; Sheppard, D. A.

    2007-06-01

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LATs first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3 5 orders of magnitude. The ACD covers the top and four sides of the LAT tracking detector, requiring a total active area of ˜8.3 m2. The ACD detector utilizes plastic scintillator tiles with wavelength shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  20. Toward Large-Area Sub-Arcsecond X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.; Graham, Michael E.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Johnson-Wilke, Raegan L.; Kilaru, Kiranmayee; Kolodziejczak, Jeffrey J.; McMuldroch, Stuart; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Saha, Timo T.; Schattenburg, Mark L.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Vaynman, Semyon; Vikhlinin, Alexey; Wang, Xiaoli; Weisskopf, Martin C.; Wilke, Rudeger H. T.; Zhang, William W.

    2014-01-01

    The future of x-ray astronomy depends upon development of x-ray telescopes with larger aperture areas (>1 sq m) and finer angular resolution(<1).Combined with the special requirements of nested grazing incidence optics, the mass and envelope constraints of spaceborne telescopes render such advances technologically challenging. Achieving this goal will require precision fabrication, alignment, mounting, and assembly of large areas (>100 sq m) of lightweight (1 kg/sq m areal density) high quality mirrors-possibly entailing active (in-space adjustable) alignment and figure correction. This paper discusses relevant programmatic and technological issues and summarizes progress toward large area sub-arcsecond x-ray telescopes. Key words: X-ray telescopes, x-ray optics, active optics, electroactive devices, silicon mirrors, differential deposition, ion implantation.

  1. Large-area semi-transparent light-sensitive nanocrystal skins.

    PubMed

    Akhavan, Shahab; Guzelturk, Burak; Sharma, Vijay Kumar; Demir, Hilmi Volkan

    2012-11-05

    We report a large-area, semi-transparent, light-sensitive nanocrystal skin (LS-NS) platform consisting of single monolayer colloidal nanocrystals. LS-NS devices, which were fabricated over areas up to 48 cm(2) using spray-coating and several cm-squares using dip-coating, are operated on the principle of photogenerated potential buildup, unlike the conventional charge collection. Implementing proof-of-concept devices using CdTe nanocrystals with ligand removal, we observed a substantial sensitivity enhancement factor of ~73%, accompanied with a 3-fold faster response time (<100 ms). With fully sealed nanocrystal monolayers, LS-NS is found to be highly stable under ambient conditions, promising for low-cost large-area UV/visible sensing in windows and facades of smart buildings.

  2. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    SciTech Connect

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  3. Stability issues pertaining large area perovskite and dye-sensitized solar cells and modules

    NASA Astrophysics Data System (ADS)

    Castro-Hermosa, S.; Yadav, S. K.; Vesce, L.; Guidobaldi, A.; Reale, A.; Di Carlo, A.; Brown, T. M.

    2017-01-01

    Perovskite and dye-sensitized solar cells are PV technologies which hold promise for PV application. Arguably, the biggest issue facing these technologies is stability. The vast majority of studies have been limited to small area laboratory cells. Moisture, oxygen, UV light, thermal and electrical stresses are leading the degradation causes. There remains a shortage of stability investigations on large area devices, in particular modules. At the module level there exist particular challenges which can be different from those at the small cell level such as encapsulation (not only of the unit cells but of interconnections and contacts), non-uniformity of the layer stacks and unit cells, reverse bias stresses, which are important to investigate for technologies that aim for industrial acceptance. Herein we present a review of stability investigations published in the literature pertaining large area perovskite and dye-sensitized solar devices fabricated both on rigid (glass) and flexible substrates.

  4. Improvement of Gas-Sensing Performance of Large-Area Tungsten Disulfide Nanosheets by Surface Functionalization.

    PubMed

    Ko, Kyung Yong; Song, Jeong-Gyu; Kim, Youngjun; Choi, Taejin; Shin, Sera; Lee, Chang Wan; Lee, Kyounghoon; Koo, Jahyun; Lee, Hoonkyung; Kim, Jongbaeg; Lee, Taeyoon; Park, Jusang; Kim, Hyungjun

    2016-10-05

    Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising gas-sensing materials due to their large surface-to-volume ratio. However, their poor gas-sensing performance resulting from the low response, incomplete recovery, and insufficient selectivity hinders the realization of high-performance 2D TMDC gas sensors. Here, we demonstrate the improvement of gas-sensing performance of large-area tungsten disulfide (WS2) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS2 nanosheets were synthesized through atomic layer deposition of WO3 followed by sulfurization. The pristine WS2 gas sensors exhibited a significant response to acetone and NO2 but an incomplete recovery in the case of NO2 sensing. After AgNW functionalization, the WS2 gas sensor showed dramatically improved response (667%) and recovery upon NO2 exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors.

  5. Very Large Area/Volume Microwave ECR Plasma and Ion Source

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor); Patterson, Michael J. (Inventor)

    2009-01-01

    The present invention is an apparatus and method for producing very large area and large volume plasmas. The invention utilizes electron cyclotron resonances in conjunction with permanent magnets to produce dense, uniform plasmas for long life ion thruster applications or for plasma processing applications such as etching, deposition, ion milling and ion implantation. The large area source is at least five times larger than the 12-inch wafers being processed to date. Its rectangular shape makes it easier to accommodate to materials processing than sources that are circular in shape. The source itself represents the largest ECR ion source built to date. It is electrodeless and does not utilize electromagnets to generate the ECR magnetic circuit, nor does it make use of windows.

  6. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Lægsgaard, Jesper

    2013-07-29

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions.

  7. Vanadium Dioxide as a Natural Disordered Metamaterial: Perfect Thermal Emission and Large Broadband Negative Differential Thermal Emittance

    NASA Astrophysics Data System (ADS)

    Kats, Mikhail A.; Blanchard, Romain; Zhang, Shuyan; Genevet, Patrice; Ko, Changhyun; Ramanathan, Shriram; Capasso, Federico

    2013-10-01

    We experimentally demonstrate that a thin (approximately 150-nm) film of vanadium dioxide (VO2) deposited on sapphire has an anomalous thermal emittance profile when heated, which arises because of the optical interaction between the film and the substrate when the VO2 is at an intermediate state of its insulator-metal transition (IMT). Within the IMT region, the VO2 film comprises nanoscale islands of the metal and dielectric phases and can thus be viewed as a natural, disordered metamaterial. This structure displays “perfect” blackbodylike thermal emissivity over a narrow wavelength range (approximately 40cm-1), surpassing the emissivity of our black-soot reference. We observe large broadband negative differential thermal emittance over a >10°C range: Upon heating, the VO2-sapphire structure emits less thermal radiation and appears colder on an infrared camera. Our experimental approach allows for a direct measurement and extraction of wavelength- and temperature-dependent thermal emittance. We anticipate that emissivity engineering with thin-film geometries comprising VO2 and other thermochromic materials will find applications in infrared camouflage, thermal regulation, and infrared tagging and labeling.

  8. Switching to BCL-6 Negativity in Relapsed Diffuse Large B Cell Lymphoma Correlated with More Aggressive Disease Course.

    PubMed

    Todorović, Milena; Balint, Bela; Andjelic, Bosko; Radisavljevic, Ziv; Mihaljevic, Biljana

    2014-12-01

    Diffuse large B-cell lymphoma (DLBCL) is the most frequent, complex and heterogeneous lymphoma of adulthood. Heterogeneity is expressed at clinical, genetic, and molecular levels. It is known that BCL-6 expression is a favorable prognostic factor in DLBCL. However, the underlying mechanisms of BCL-6 expression in DLBCL relapse are not yet elucidated. Here, we present so far undescribed clinical phenomenon of switching BCL-6(+) protein expression into BCL-6(-) expression in 19 of 41 relapsed DLBCL patients. The switch in relapsed DLBCL was associated with more aggressive clinical course of the disease. Bone marrow infiltration and high IPI risk were more often present in BCL-6(-) patients. Significantly increased biochemical parameters, such as LDH, beta-2 macroglobulin, CRP, and ferritin have been found, as well as significantly decreased serum Fe, TIBC, and hemoglobin. A Ki-67 proliferation marker was considerably high in relapsed DLBCL, but without significant differences between BCL-6(+) and BCL-6(-) groups of patients. Thus, switching of the positive into negative BCL-6 expression during DLBCL relapse could be used as a prognostic factor and a valuable criterion for treatment decision.

  9. gram-scale metafluids and large area tunable metamaterials: design, fabrication, and nano-optical tomographic characterization (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dionne, Jennifer A.

    2016-09-01

    Advances in metamaterials and metasurfaces have enabled unprecedented control of light-matter interactions. Metamaterial constituents support high-frequency electric and magnetic dipoles, which can be used as building blocks for new materials capable of negative refraction, electromagnetic cloaking, strong visible-frequency circular dichroism, and enhanced magnetic or chiral transitions in ions and molecules. However, most metamaterials to date have been limited to solid-state, static, narrow-band, and/or small-area structures. Here, we introduce the design, fabrication, and three-dimensional nano-optical characterization of large-area, dynamically-tunable metamaterials and gram-scale metafluids. First, we use transformation optics to design a broadband metamaterial constituent - a metallo-dielectric nanocrescent - characterized by degenerate electric and magnetic dipoles. A periodic array of nanocrescents exhibits large positive and negative refractive indices at optical frequencies, confirmed through simulations of plane wave refraction through a metamaterial prism. Simulations also reveal that the metamaterial optical properties are largely insensitive to the wavelength, orientation and polarization of incident light. Then, we introduce a new tomographic technique, cathodoluminescence (CL) spectroscopic tomography, to probe light-matter interactions in individual nanocrescents with nanometer-scale resolution. Two-dimensional CL maps of the three-dimensional nanostructure are obtained at various orientations, while a filtered back projection is used to reconstruct the CL intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. Finally, we demonstrate the fabrication of dynamically tunable large-area metamaterials and gram-scale metafluids, using a

  10. Ultrahigh Performance C60 Nanorod Large Area Flexible Photoconductor Devices via Ultralow Organic and Inorganic Photodoping

    PubMed Central

    Saran, Rinku; Stolojan, Vlad; Curry, Richard J.

    2014-01-01

    One dimensional single-crystal nanorods of C60 possess unique optoelectronic properties including high electron mobility, high photosensitivity and an excellent electron accepting nature. In addition, their rapid large scale synthesis at room temperature makes these organic semiconducting nanorods highly attractive for advanced optoelectronic device applications. Here, we report low-cost large-area flexible photoconductor devices fabricated using C60 nanorods. We demonstrate that the photosensitivity of the C60 nanorods can be enhanced ~400-fold via an ultralow photodoping mechanism. The photodoped devices offer broadband UV-vis-NIR spectral tuneability, exhibit a detectivitiy >109 Jones, an external quantum efficiency of ~100%, a linear dynamic range of 80 dB, a rise time 60 µs and the ability to measure ac signals up to ~250 kHz. These figures of merit combined are among the highest reported for one dimensional organic and inorganic large-area planar photoconductors and are competitive with commercially available inorganic photoconductors and photoconductive cells. With the additional processing benefits providing compatibility with large-area flexible platforms, these devices represent significant advances and make C60 nanorods a promising candidate for advanced photodetector technologies. PMID:24853479

  11. Large Area Superconducting TES Spiderweb Bolometer for Multi-mode Cavity Microwave Detect

    NASA Astrophysics Data System (ADS)

    Biasotti, M.; Bagliani, D.; Corsini, D.; De Bernardis, P.; Gatti, F.; Gualtieri, R.; Lamagna, L.; Masi, S.; Pizzigoni, G.; Schillaci, A.

    2014-05-01

    For the cosmic microwave background, the increase of the sensitivity of present superconducting TES Spiderweb Bolometers can be done coupling them to a large set of modes of the EM radiation inside the cavity. This will require a proper shaping of the horn-cavity assembly for the focal plane of the microwave telescope and the use of large area bolometers. Large area spiderweb bolometers of 8 mm diameter and a mesh size of 250 μm are fabricated in order to couple with approximately the first 20 modes of the cavity at about 140 GHz. These bolometers are fabricated with micro machining techniques from silicon wafer covered with SiO2 - Si3N4 CVD thick films, 0.3 μm and 1 μm respectively. The sensor is a Ti/Au/Ti 3 layer TES sensor with Tc tuned in the 330-380 mK and 2 mK transition width. The TES is electronically coupled to the EM gold absorber that is grown on to the spiderweb mesh in order to sense the temperature of the electron gas heated by the EM radiation. The gold absorber mesh has 5 um beam size over a Si3N4 10 μm beam size supporting mesh. The Si3N4 mesh is then fully suspended by means of DRIE back etching of the Si substrate. Here we present the first results of these large area bolometers.

  12. A novel lithography technique for formation of large areas of uniform nanostructures

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Dey, Dibyendu; Memis, Omer G.; Katsnelson, Alex; Mohseni, Hooman

    2008-08-01

    With nanotechnology becoming widely used, many applications such as plasmonics, sensors, storage devices, solar cells, nano-filtration and artificial kidneys require the structures with large areas of uniform periodic nanopatterns. Most of the current nano-manufacturing techniques, including photolithography, electron-beam lithography, and focal ion beam milling, are either slow or expensive to be applied into the areas. Here, we demonstrate an alternative and novel lithography technique - Nanosphere Photolithography (NSP) - that generates a large area of highly uniform periodic nanoholes or nanoposts by utilizing the monolayer of hexagonally close packed (HCP) silica microspheres as super-lenses on top of photoresist. The size of the nanopatterns generated is almost independent of the sphere sizes and hence extremely uniform patterns can be obtained. We demonstrate that the method can produce hexagonally packed arrays of hole of sub-250 nm size in positive photoresist using a conventional exposure system with a broadband UV source centered at 400 nm. We also show a large area of highly uniform gold nanoholes (~180 nm) and nanoposts (~300nm) array with the period of 1 μm fabricated by the combination of lift-off and NSP. The process is not limited to gold. Similar structures have been shown with aluminum and silicon dioxide layer. The period and size of the structures can also be tuned by changing proper parameters. The technique applying self-assembled and focusing properties of micro-/nano-spheres into photolithography establishes a new paradigm for mask-less photolithography technique, allowing rapid and economical creation of large areas of periodic nanostructures with a high throughput.

  13. A route to high surface area, porosity and inclusion of large molecules in crystals.

    PubMed

    Chae, Hee K; Siberio-Pérez, Diana Y; Kim, Jaheon; Go, YongBok; Eddaoudi, Mohamed; Matzger, Adam J; O'Keeffe, Michael; Yaghi, Omar M

    2004-02-05

    One of the outstanding challenges in the field of porous materials is the design and synthesis of chemical structures with exceptionally high surface areas. Such materials are of critical importance to many applications involving catalysis, separation and gas storage. The claim for the highest surface area of a disordered structure is for carbon, at 2,030 m2 g(-1) (ref. 2). Until recently, the largest surface area of an ordered structure was that of zeolite Y, recorded at 904 m2 g(-1) (ref. 3). But with the introduction of metal-organic framework materials, this has been exceeded, with values up to 3,000 m2 g(-1) (refs 4-7). Despite this, no method of determining the upper limit in surface area for a material has yet been found. Here we present a general strategy that has allowed us to realize a structure having by far the highest surface area reported to date. We report the design, synthesis and properties of crystalline Zn4O(1,3,5-benzenetribenzoate)2, a new metal-organic framework with a surface area estimated at 4,500 m2 g(-1). This framework, which we name MOF-177, combines this exceptional level of surface area with an ordered structure that has extra-large pores capable of binding polycyclic organic guest molecules--attributes not previously combined in one material.

  14. Comparison of ozone temporal scales for large urban, small urban, and rural areas in Georgia.

    PubMed

    Maxwell-Meier, Kari L; Chang, Michael E

    2005-10-01

    Ground-level ozone (O3) time series are characterized by the sum of several distinct temporal scales: long-term, seasonal, synoptic, diurnal (daily), and intraday variation. In this study, the authors use a Kolmorogov-Zurbenko filter to separate the 1981-2001 O3 time-series from many sites in and around Georgia into these various components. The authors compare the temporal components to examine differences between small and large metropolitan areas and between urban and rural areas. They then focus on the synoptic component to define a predominant transport region or airshed for each site.

  15. Large-area linear Silicon Drift Detector design for X-ray experiments

    NASA Astrophysics Data System (ADS)

    Rachevski, A.; Zampa, G.; Zampa, N.; Campana, R.; Evangelista, Y.; Giacomini, G.; Picciotto, A.; Bellutti, P.; Feroci, M.; Labanti, C.; Piemonte, C.; Vacchi, A.

    2014-07-01

    A large area, 120 × 72 mm2, linear Silicon Drift Detector (SDD) has been developed for X-ray spectroscopy in the 2-50 keV energy range. Elaborated via a number of prototypes, the final detector design, REDSOX1, features elements to meet the requirements of a modern space-borne X-ray detector with a power consumption per sensitive area below 0.5 mW/cm2, offering the possibility to perform timing and spectroscopy X-ray observations on a ten microseconds scale.

  16. Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

    SciTech Connect

    Saraf, Laxmikant V.; Britt, David W.

    2011-09-14

    We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

  17. Evaluation of large area crop estimation techniques using LANDSAT and ground-derived data. [Missouri

    NASA Technical Reports Server (NTRS)

    Amis, M. L.; Lennington, R. K.; Martin, M. V.; Mcguire, W. G.; Shen, S. S. (Principal Investigator)

    1981-01-01

    The results of the Domestic Crops and Land Cover Classification and Clustering study on large area crop estimation using LANDSAT and ground truth data are reported. The current crop area estimation approach of the Economics and Statistics Service of the U.S. Department of Agriculture was evaluated in terms of the factors that are likely to influence the bias and variance of the estimator. Also, alternative procedures involving replacements for the clustering algorithm, the classifier, or the regression model used in the original U.S. Department of Agriculture procedures were investigated.

  18. Coatings for large-area low-cost solar concentrators and reflectors

    NASA Astrophysics Data System (ADS)

    Martin, Peter M.; Affinito, John D.; Gross, Mark E.; Bennett, Wendy D.

    1994-09-01

    Large-optics coating facilities and processes at Pacific Northwest Laboratory (PNL) that were used to develop large-area high-performance laser mirrors for SDIO are now being used to fabricate a variety of optical components for commercial clients, and for novel applications for other DoD clients. Emphasis of this work is on technology transfer of low-cost coating processes and equipment to private clients. Much of the technology transfer is being accomplished through the CRADA (Cooperative Research and Development Agreement) process funded by the Department of Energy (DOE).

  19. Large-Area Atom Interferometry with Frequency-Swept Raman Adiabatic Passage.

    PubMed

    Kotru, Krish; Butts, David L; Kinast, Joseph M; Stoner, Richard E

    2015-09-04

    We demonstrate light-pulse atom interferometry with large-momentum-transfer atom optics based on stimulated Raman transitions and frequency-swept adiabatic rapid passage. Our atom optics have produced momentum splittings of up to 30 photon recoil momenta in an acceleration-sensitive interferometer for laser cooled atoms. We experimentally verify the enhancement of phase shift per unit acceleration and characterize interferometer contrast loss. By forgoing evaporative cooling and velocity selection, this method lowers the atom shot-noise-limited measurement uncertainty and enables large-area atom interferometry at higher data rates.

  20. Procedures and results of the measurements on large area photomultipliers for the NEMO project

    NASA Astrophysics Data System (ADS)

    Aiello, S.; Leonora, E.; Aloisio, A.; Ameli, F.; Amore, I.; Anghinolfi, M.; Anzalone, A.; Barbarino, G.; Barbarito, E.; Battaglieri, M.; Bazzotti, M.; Bellotti, R.; Bersani, A.; Beverini, N.; Biagi, S.; Bonori, M.; Bouhdaef, B.; Cacopardo, G.; Calı, C.; Capone, A.; Caponetto, L.; Carminati, G.; Cassano, B.; Ceres, A.; Chiarusi, T.; Circella, M.; Cocimano, R.; Coniglione, R.; Cordelli, M.; Costa, M.; D'Amico, A.; DeBonis, G.; DeRosa, G.; DeRuvo, G.; DeVita, R.; Distefano, C.; Flaminio, V.; Fratini, K.; Gabrielli, A.; Galeotti, S.; Gandolfi, E.; Giacomelli, G.; Giorgi, F.; Giovanetti, G.; Grimaldi, A.; Grmek, A.; Habel, R.; Imbesi, M.; Lonardo, A.; LoPresti, D.; Lucarelli, F.; Margiotta, A.; Marinelli, A.; Martini, A.; Masullo, R.; Maugeri, F.; Migneco, E.; Minutoli, S.; Mongelli, M.; Morganti, M.; Musico, P.; Musumeci, M.; Orlando, A.; Osipenko, M.; Papaleo, R.; Pappalardo, V.; Piattelli, P.; Piombo, D.; Raffaelli, F.; Raia, G.; Randazzo, N.; Reito, S.; Ricco, G.; Riccobene, G.; Ripani, M.; Rovelli, A.; Ruppi, M.; Russo, G. V.; Russo, S.; Sapienza, P.; Sedita, M.; Shirokov, E.; Simeone, F.; Sciliberto, D.; Sipala, V.; Sollima, C.; Spurio, M.; Stefani, F.; Taiuti, M.; Terreni, G.; Trasatti, L.; Urso, S.; Vecchi, M.; Vicini, P.; Wischnewski, R.

    2010-03-01

    The selection of the photomultiplier plays a crucial role in the R&D activity related to a large-scale underwater neutrino telescope. This paper illustrates the main procedures and facilities used to characterize the performances of 72 large area photomultipliers, Hamamatsu model R7081 sel. The voltage to achieve a gain of 5×10 7, dark count rate and single photoelectron time and charge properties of the overall response were measured with a properly attenuated 410 nm pulsed laser. A dedicated study of the spurious pulses was also performed. The results prove that the photomultipliers comply with the general requirements imposed by the project.

  1. Fermi Large Area Telescope Observations of the Dark Accelerator HESS J1745-303

    NASA Astrophysics Data System (ADS)

    Yeung, Paul

    2016-12-01

    Reviewing the two MeV-GeV investigations in the field of the HESS J1745-303 performed using Fermi Large Area Telescope data, we confirmed that the emission peak comfortably coincides with ‘Region A’ in the TeV regime, which is the brightest part of this feature. The MeV–TeV spectrum can be precisely described by a single power-law. Also, recent investigation has shown that the MeV-GeV feature is elongated from ‘Region A’ toward the north-west, which is similar to the case of large- scale atomic/molecular gas distribution.

  2. Extraordinary suppression of carrier scattering in large area graphene oxide films

    SciTech Connect

    Negishi, R. Kobayashi, Y.

    2014-12-22

    In this study, we find that thermal treatment in ethanol vapor has a remarkable suppression effect of carrier scattering occurring between reduced graphene oxide (rGO) flakes in large area films. We observe excellent electrical properties such as high carrier mobility (∼5 cm{sup 2}/Vs) and low sheet resistance (∼40 KΩ/□) for the rGO films. From the electrical conductivity analysis of large area rGO films using two-dimensional variable range hopping model and structural analysis using Raman spectra measured from the rGO films, we reveal that the significant effect is caused by the expansion of conjugated π-electron system in rGO flake due to the efficient restoration of graphitic structure.

  3. Large-area chromogenics: Materials and devices for transmittance control. Volume IS 4

    SciTech Connect

    Lampert, C.M.; Granqvist, C.G.

    1990-12-31

    Chromogenic materials can alter their optical properties in a persistent yet reversible manner when subjected to a change in external conditions such as irradiation intensity, temperature, or electric-field strength. In the future chromogenic materials may be used on large scale to regulate the throughput of radiant energy for windows in buildings and cars, so that comfortable lighting and temperature are maintained without excessive air conditioning. The purpose of this book is to give a broad coverage of large-area chromogenics and to discuss their applications. The book is divided into the following areas: applications; photochromic materials; thermochromic materials; inorganic electrochromic materials; inorganic electrochromic materials; organic electrochromic materials; conductors for ions and electrons in electrochromic devices; electrochromic devices; and liquid crystals materials and devices. Separate abstracts were prepared for 33 papers in this book.

  4. Cladding doped defect-core large mode area W-type photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Boruah, Jiten; Kalra, Yogita; Sinha, Ravindra K.

    2016-09-01

    Propagation characteristics of a cladding doped defect-core large mode area W-type photonic crystal fiber have been investigated by using finite element method. In the proposed structure the central air hole has been removed to form the defect core and the second layer of cladding rings around the central core have been selectively doped with different concentration of fluorine to tune the refractive index of the doped silica rods. The bend loss, dispersion, effect of bending on dispersion, and nonlinear coefficient of the proposed photonic crystal fiber design has been numerically investigated. The proposed W-type photonic crystal fiber has low bend loss, low dispersion, large-mode-area with low value of nonlinear coefficient at wavelength of 1.55μm. The structure can be utilized for telecommunication applications, for applications in high power fiber lasers, amplifiers and sensors.

  5. Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

    PubMed Central

    Kim, Dae-Hyeong; Ghaffari, Roozbeh; Lu, Nanshu; Wang, Shuodao; Lee, Stephen P.; Keum, Hohyun; D’Angelo, Robert; Klinker, Lauren; Su, Yewang; Lu, Chaofeng; Kim, Yun-Soung; Ameen, Abid; Li, Yuhang; Zhang, Yihui; de Graff, Bassel; Hsu, Yung-Yu; Liu, ZhuangJian; Ruskin, Jeremy; Xu, Lizhi; Lu, Chi; Omenetto, Fiorenzo G.; Huang, Yonggang; Mansour, Moussa; Slepian, Marvin J.; Rogers, John A.

    2012-01-01

    Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation. PMID:23150574

  6. Preparation of large-area double-walled carbon nanotube films and application as film heater

    NASA Astrophysics Data System (ADS)

    Wu, Zi Ping; Wang, Jian Nong

    2009-11-01

    Large-area (larger than 30×30 cm 2) double-walled carbon nanotube (DWCNT) films are prepared and application as a heating element for film heaters is demonstrated. A high heating efficiency is observed. Measurements indicate that the use of the DWCNT film heater would save energy consumption up to 20-30% when compared with a commercial film-like metal-based heater. Morphological analysis reveals that the special surface structure, appropriate electric and high thermal conductivities of the film formed by the network of entangled nanotube bundles may lead to the high heating performance. Considering large-area, shape flexibility, negligible weight and easy manipulation, the film exhibits promising potential applications as a film heater for thermal control in aircrafts, medical equipment, home appliances and other industrial fields at low temperature (below 400 °C).

  7. Large-area binary blazed grating coupler between nanophotonic waveguide and LED.

    PubMed

    Li, Hongqiang; Zhou, Wenqian; Zhang, Meiling; Liu, Yu; Zhang, Cheng; Li, Enbang; Miao, Changyun; Tang, Chunxiao

    2014-01-01

    A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG) demodulation integrated microsystem on silicon-on-insulator (SOI) was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm.

  8. Large area mapping of soil moisture using the ESTAR passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Levine, D. M.; Swift, C. T.; Schmugge, T. J.

    1994-01-01

    Investigations designed to study land surface hydrologic-atmospheric interactions, showing the potential of L band passive microwave radiometry for measuring surface soil moisture over large areas, are discussed. Satisfying the data needs of these investigations requires the ability to map large areas rapidly. With aircraft systems this means a need for more beam positions over a wider swath on each flightline. For satellite systems the essential problem is resolution. Both of these needs are currently being addressed through the development and verification of Electronically Scanned Thinned Array Radiometer (ESTAR) technology. The ESTAR L band radiometer was evaluated for soil moisture mapping applications in two studies. The first was conducted over the semiarid rangeland Walnut Gulch watershed located in south eastern Arizona (U.S.). The second was performed in the subhumid Little Washita watershed in south west Oklahoma (U.S.). Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems.

  9. Uniform and large area deposition of diamond-like carbon using RF source ion beam

    SciTech Connect

    Wu, R.L.C.; Lanter, W.; Miyoshi, K.; Heidger, S.L.; Bletzinger, P.; Garscadden, A.

    1995-12-31

    The authors have designed and constructed a large area ion beam apparatus to deposit DLC films onto 1,000 cm{sup 2} surfaces with various geometries. The use of an efficient RF excited ion gun (13.56 MHz, 1 kW power, 50--3,000 eV ion energy) with a diameter of 20 cm, enables one to generate various hydrocarbon ions with high ion beam currents, varying ionic species and less maintenance. The use of a four axis (X-Y-{theta}Y-{theta}Z) substrate scanner with computer control can produce uniform DLC films on large areas and curved surfaces. The effects of RF power, ion energy, gaseous composition, and total pressure on the properties of DLC have been systematically investigated.

  10. Ultrafast Nanofiltration through Large-Area Single-Layered Graphene Membranes.

    PubMed

    Qin, Yanzhe; Hu, Yongyou; Koehler, Stephan; Cai, Liheng; Wen, Junjie; Tan, Xiaojun; Xu, Weiwei L; Sheng, Qian; Hou, Xu; Xue, Jianming; Yu, Miao; Weitz, David

    2017-03-22

    Perforated single-layered graphene has demonstrated selectivity and flux that is orders of magnitude greater than state-of-the-art polymer membranes. However, only individual graphene sheets with sizes up to tens of micrometers have been successfully fabricated for pressurized permeation studies. Scaling-up and reinforcement of these atomic membranes with minimum cracks and pinholes remains a major hurdle for practical applications. We develop a large-area in situ, phase-inversion casting technique to create 63 cm(2) high-quality single-layered perforated graphene membranes for ultrafast nanofiltration that can operate at pressures up to 50 bar. This result demonstrates the feasibility of our technique for creating robust large-area, high quality, single-layered graphene and its potential use as a pressurized nanofiltration membrane.

  11. Development of a large-area Multigap RPC with adequate spatial resolution for muon tomography

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, Y.; Wang, X.; Zeng, M.; Xie, B.; Han, D.; Lyu, P.; Wang, F.; Li, Y.

    2016-11-01

    We study the performance of a large-area 2-D Multigap Resistive Plate Chamber (MRPC) designed for muon tomography with high spatial resolution. An efficiency up to 98% and a spatial resolution of around 270 μ m are obtained in cosmic ray and X-ray tests. The performance of the MRPC is also investigated for two working gases: standard gas and pure Freon. The result shows that the MRPC working in pure Freon can provide higher efficiency and better spatial resolution.

  12. Fabrication of large-area and low mass critical-angle x-ray transmission gratings

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2014-07-01

    Soft x-ray spectroscopy of celestial sources with high resolving power R = E/ΔE and large collecting area addresses important science listed in the Astro2010 Decadal Survey New Worlds New Horizons, such as the growth of the large scale structure of the universe and its interaction with active galactic nuclei, the kinematics of galactic outflows, as well as coronal emission from stars and other topics. Numerous studies have shown that a transmission grating spectrometer based on lightweight critical-angle transmission (CAT) gratings can deliver R = 3000-5000 and large collecting area with high efficiency and minimal resource requirements, providing spectroscopic figures of merit at least an order of magnitude better than grating spectrometers on Chandra and XMM-Newton, as well as future calorimeter-based missions. The recently developed CAT gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Their working principle based on blazing through reflection off the smooth, ultra-high aspect ratio grating bar sidewalls has previously been demonstrated on small samples with x rays. For larger gratings (area greater than 1 inch square) we developed a fabrication process for grating membranes with a hierarchy of integrated low-obscuration supports. The fabrication involves a combination of advanced lithography and highly anisotropic dry and wet etching techniques. We report on the latest fabrication results of free-standing, large-area CAT gratings with polished sidewalls and preliminary x-ray tests.

  13. Ultra-violet light-emitting diode calibration system for timing large area scintillation detectors

    NASA Astrophysics Data System (ADS)

    Naumov, P. Yu; Runtso, M. F.; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    Timing large area plastic scintillation detectors are developing for the space gamma-ray telescopes now. For the in-flight calibration of these detectors the use of ultra-violet light-emitting diode, irradiating the 1 m long detector module at the center of its lateral side is suggested. The results of the measurements show the possibility of this calibration system implementation as for amplitude as for timing properties monitoring.

  14. Long-term mode shape degradation in large mode area Yb-doped pulsed fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Bobkov, K. K.; Bubnov, M. M.; Aleshkina, S. S.; Likhachev, M. E.

    2017-01-01

    Experimental observation of long-term output mode shape degradation in pulsed Yb-doped fiber amplifiers is reported for the first time. The process occurs in large mode area Yb-doped fibers and is caused by the formation of the long period grating responsible for power transfer from the fundamental mode to the first high-order mode. The linkage between the process and photodarkening was revealed.

  15. Caustic Recycle from Hanford Tank Waste Using Large Area NaSICON Structures (LANS)

    SciTech Connect

    Fountain, Matthew S.; Sevigny, Gary J.; Balagopal, S.; Bhavaraju, S.

    2009-03-31

    This report presents the results of a 5-day test of an electrochemical bench-scale apparatus using a proprietary (NAS-GY) material formulation of a (Na) Super Ion Conductor (NaSICON) membrane in a Large Area NaSICON Structures (LANS) configuration. The primary objectives of this work were to assess system performance, membrane seal integrity, and material degradation while removing Na from Group 5 and 6 tank waste from the Hanford Site.

  16. Large-area thin self-supporting carbon foils with MgO coatings

    NASA Astrophysics Data System (ADS)

    Stolarz, Anna; Maier-Komor, Peter

    2002-03-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 μg/cm 2, coated with approximately 4 μg/cm 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  17. Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays

    DTIC Science & Technology

    2012-06-08

    REPORT Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: This program...monolithically-integrated building blocks (individual laser channels) of high power beam-combined fiber laser arrays. Robust single-mode performance...of CCC fibers with core sizes of up to ~60?m has been rigorously demonstrated. Various CCC fiber based high power lasers have been also

  18. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-02-15

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber.

  19. Lithography-free large-area metamaterials for stable thermophotovoltaic energy conversion

    DOE PAGES

    Coppens, Zachary J.; Kravchenko, Ivan I.; Valentine, Jason G.

    2016-02-08

    A large-area metamaterial thermal emitter is fabricated using facile, lithography-free techniques. The device is composed of conductive oxides, refractory ceramics, and noble metals and shows stable, selective emission after exposure to 1173 K for 22 h in oxidizing and inert atmospheres. Lastly, the results indicate that the metamaterial can be used to achieve high-performance thermophotovoltaic devices for applications such as portable power generation.

  20. [Preparation of large area Al-ZnO thin film by DC magnetron sputtering].

    PubMed

    Jiao, Fei; Liao, Cheng; Han, Jun-Feng; Zhou, Zhen

    2009-03-01

    Solar cells of p-CIS/n-buffer/ZnO type, where CIS is (CuInS2, CuInSe2 or intermediates, are thin-film-based devices for the future high-efficiency and low-cost photovoltaic devices. As important thin film, the properties of Al-doped ZnO (AZO) directly affect the parameter of the cell, especially for large volume. In the present paper, AZO semiconductor transparent thin film on soda-lime glass was fabricated using cylindrical zinc-aluminum target, which can not only lower the cost of the target but also make the preparation of large area AZO thin film more easily. Using the DC magnet sputtering techniques and rolling target, high utilization efficiency of target was achieved and large area uniform and directional film was realized. An introduction to DC magnet sputtering techniques for large area film fabrication is given. With different measurement methods, such as X-ray diffraction (XRD) and scan electron microscope (SEM), we analyzed large size film's structure, appearance, and electrical and optical characteristics. The XRD spectrum indicated that the AZO film shows well zinc-blende structure with a preferred (002) growth and the c-axis is oriented normal to the substrate plane. The lattice constant is 5.603 9 nm and the mismatch with CdS thin film is only 2 percent. It absolutely satisfied the demand of the GIGS solar cell. The cross-section of the AZO thin film indicates the columnar structure and the surface morphology shows that the crystal size is about 50 nm that is consistent with the result of XRD spectrum. By the optical transmission curve, not only the high transmission rate over 85 percent in the visible spectrum between 400 nm and 700 nm was showed but also the band gap 3.1 eV was estimated. And all these parameters can meet the demand of the large area module of GIGS solar cell. The result is that using alloy target and Ar gas, and controlling the appropriate pressure of oxygen, we can get directional, condensed, uniform, high transmitting rate, low

  1. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities

    PubMed Central

    Borg, Bridget L.; Arthur, Stephen M.; Bromen, Nicholas A.; Cassidy, Kira A.; McIntyre, Rick; Smith, Douglas W.; Prugh, Laura R.

    2016-01-01

    The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997–2013 and YNP from 2008–2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies. PMID:27124729

  2. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities.

    PubMed

    Borg, Bridget L; Arthur, Stephen M; Bromen, Nicholas A; Cassidy, Kira A; McIntyre, Rick; Smith, Douglas W; Prugh, Laura R

    2016-01-01

    The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997-2013 and YNP from 2008-2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies.

  3. How diversification rates and diversity limits combine to create large-scale species–area relationships

    PubMed Central

    Kisel, Yael; McInnes, Lynsey; Toomey, Nicola H.; Orme, C. David L.

    2011-01-01

    Species–area relationships (SARs) have mostly been treated from an ecological perspective, focusing on immigration, local extinction and resource-based limits to species coexistence. However, a full understanding across large regions is impossible without also considering speciation and global extinction. Rates of both speciation and extinction are known to be strongly affected by area and thus should contribute to spatial patterns of diversity. Here, we explore how variation in diversification rates and ecologically mediated diversity limits among regions of different sizes can result in the formation of SARs. We explain how this area-related variation in diversification can be caused by either the direct effects of area or the effects of factors that are highly correlated with area, such as habitat diversity and population size. We also review environmental, clade-specific and historical factors that affect diversification and diversity limits but are not highly correlated with region area, and thus are likely to cause scatter in observed SARs. We present new analyses using data on the distributions, ages and traits of mammalian species to illustrate these mechanisms; in doing so we provide an integrated perspective on the evolutionary processes shaping SARs. PMID:21807732

  4. [Effects of large-area planting water hyacinth on macro-benthos community structure and biomass].

    PubMed

    Liu, Guo-Feng; Liu, Hai-Qin; Zhang, Zhi-Yong; Zhang, Ying-Ying; Yan, Shao-Hua; Zhong, Ji-Cheng; Fan, Cheng-Xin

    2010-12-01

    The effects on macro-benthos and benthos environment of planting 200 hm2 water hyacinth (E. crassipens) in Zhushan Bay, Lake Taihu, were studied during 8-10 months consecutive surveys. Results indicated that average densities of mollusca (the main species were Bellamya aeruginosa) in far-planting, near-planting and planting area were 276.67, 371.11 and 440.00 ind/m2, respectively, and biomass were 373.15, 486.57 and 672.54 g/m2, respectively, showed that average density and biomass of planting area's were higher than those of others. However, the average density and biomass of Oligochaeta (the main species was Limodrilus hoffmeisteri) and Chironomidae in planting area were lower than that of outside planting area. The density and biomass of three dominant species of benthic animal increased quickly during 8-9 months, decreased quickly in October inside and outside water hyacinth planting area. The reason of this phenomenon could be possible that lots of cyanobacteria cells died and consumed dissolve oxygen in proceed decomposing. Algae cells released lots of phosphorus and nitrogen simultaneously, so macro-benthos died in this environment. The indexes of Shannon-Weaver and Simpson indicated that water environment was in moderate polluted state. On the basis of the survey results, the large-area and high-density planting water hyacinth haven't demonstrated a great impact on macrobenthos and benthos environment in short planting time (about 6 months planting time).

  5. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    NASA Astrophysics Data System (ADS)

    Swatantran, Anu; Tang, Hao; Barrett, Terence; Decola, Phil; Dubayah, Ralph

    2016-06-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping.

  6. Large Area X-ray Proportional Counter (LAXPC) instrument onboard ASTROSAT

    NASA Astrophysics Data System (ADS)

    Yadav, J. S.; Agrawal, P. C.; Antia, H. M.; Chauhan, Jai Verdhan; Dedhia, Dhiraj; Katoch, Tilak; Madhwani, P.; Manchanda, R. K.; Misra, Ranjeev; Pahari, Mayukh; Paul, B.; Shah, Parag

    2016-07-01

    ASTROSAT, India's first dedicated astronomy space mission was launched on September 28, 2015. The Large Area X-ray Proportional Counter (LAXPC) is one of the major payloads on ASTROSAT. A cluster of three co-aligned identical LAXPC detectors provide large area of collection .The large detection volume (15 cm depth) filled with mixture of xenon gas (90(%) and methane (10%) at 2 atmospheres pressure, results in detection efficiency greater than 50%, above 30 keV. The LAXPC instrument is best suited for X-ray timing and spectral studies. It will provide the largest effective area in 3-80 keV range among all the satellite missions flown so far worldwide and will remain so for the next 5-10 years. The LAXPC detectors have been calibrated using radioactive sources in the laboratory. GEANT4 simulation for LAXPC detectors was carried out to understand detector background and its response. The LAXPC instrument became fully operational on 19th October 2015 for the first time in space. We have performed detector calibration in orbit. The LAXPC instrument is functioning well and has achieved all detector parameters proposed initially. In this paper, we will describe LAXPC detector calibration in lab as well as in orbit along with first results.

  7. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    PubMed Central

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-01-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping. PMID:27329078

  8. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar.

    PubMed

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-06-22

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km(2)). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping.

  9. Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

    PubMed Central

    Yao, Yao; Glisic, Branko

    2015-01-01

    Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs. PMID:25853407

  10. Testing of a Neon Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2014-01-01

    Cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks is required for future NASA missions. A cryogenic loop heat pipe (CLHP) can provide a closed-loop cooling system for this purpose and has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A neon CLHP was tested extensively in a thermal vacuum chamber using a cryopump as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components. Tests conducted included loop cool-down from the ambient temperature, startup, power cycle, heat removal capability, loop capillary limit and recovery from a dry-out, low power operation, and long duration steady state operation. The neon CLHP demonstrated robust operation. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by applying power to both the pump and evaporator without any pre-conditioning. It could adapt to changes in the pump power andor evaporator power, and reach a new steady state very quickly. The evaporator could remove heat loads between 0.25W and 4W. When the pump capillary limit was exceeded, the loop could resume its normal function by reducing the pump power. Steady state operations were demonstrated for up to 6 hours. The ability of the neon loop to cool large areas was therefore successfully verified.

  11. Toward Large-Area Sub-Arcsecond X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.; Graham, Michael E.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Johnson-Wilke, Raegan L.; Kilaru, Kiranmayee; Kolodziejczak, Jeffery J.; Lillie, Charles F.; McMuldroch, Stuart; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Saha, Timo T.; Weisskopf, Martin C.; Zhang, William W.

    2014-01-01

    The future of x-ray astronomy depends upon development of x-ray telescopes with larger aperture areas (approx. = 3 square meters) and fine angular resolution (approx. = 1 inch). Combined with the special requirements of nested grazing-incidence optics, the mass and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. Achieving this goal will require precision fabrication, alignment, mounting, and assembly of large areas (approx. = 600 square meters) of lightweight (approx. = 1 kilogram/square meter areal density) high-quality mirrors at an acceptable cost (approx. = 1 million dollars/square meter of mirror surface area). This paper reviews relevant technological and programmatic issues, as well as possible approaches for addressing these issues-including active (in-space adjustable) alignment and figure correction.

  12. Large area, low capacitance, GaAs nanowire photodetector with a transparent Schottky collecting junction

    SciTech Connect

    Seyedi, M. A. Yao, M.; O'Brien, J.; Dapkus, P. D.; Wang, S. Y.

    2013-12-16

    We present experimental results on a GaAs/Indium-Tin-Oxide Schottky-like heterojunction photodetector based on a nanowire device geometry. By distributing the active detecting area over an array of nanowires, it is possible to achieve large area detection with low capacitance. Devices with bare GaAs and passivated AlGaAs/GaAs nanowires are fabricated to compare the responsivity with and without surface passivation. We are able to achieve responsivity of >0.5A/W and Signal-Noise-Ratio in excess of 7 dB for 2 V applied reverse bias with passivated nanowire devices. Capacitance-voltage measurement yields <5 nF/cm{sup 2}, which shows a strong possibility for high-speed applications with a broad area device.

  13. Pharmaceutical cleaning validation using non-proximate large-area desorption electrospray ionization mass spectrometry.

    PubMed

    Soparawalla, Santosh; Salazar, Gary A; Perry, Richard H; Nicholas, Mark; Cooks, R Graham

    2009-01-01

    Desorption electrospray ionization (DESI) is a droplet-based ionization method that is applied to samples in the ambient environment with little or no sample preparation. Its utility for industrial applications is explored here for the case of pharmaceutical cleaning validation. A non-proximate large-area DESI system was built to examine representative areas of the surfaces of reaction vessels used in active product ingredient (API) manufacturing. A large-area sprayer capable of sampling an area of approximately 2.5 cm(2) was coupled with a transport tube to allow sensitive, representative sampling of APIs from a stainless steel surface 1 m away from the mass spectrometer. The system was used to detect the APIs neostigmine, acebutolol, amiloride, amiodarone, ibuprofen, montelukast, potassium clavulanate, and beta-estradiol, at levels as low as 30-10 ng/cm(2), easily satisfying the general acceptable limits set by the pharmaceutical industry. These levels were achieved from surfaces resembling the equipment used in API manufacturing processes at a rate of 30 s per analysis.

  14. The Capabilities of the GLAST Large Area Telescope for Blazar Variability Studies

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2006-01-01

    One of the more notable features of the Large Area Telescope (LAT) on GLAST is its extremely large field of view, which covers more than 20% of the sky at any instant. In survey mode the LAT will be rocked about the orbital plane to provide coverage of the entire gamma-ray sky above 20 MeV every three hours. This will be the default observing mode for the first year of operations and is likely to be the dominant observing mode throughout the rest of the mission. Thus the LAT will provide long, evenly sampled, gamma-ray lightcurves for a large number of sources. In this talk we describe the nature and quality of the data that will be provided by the LAT and use simulated lightcurves to illustrate some of the scientific questions that can be addressed with LAT observations.

  15. Dark Forward Electrical Test Techniques Developed for Large-Area Photovoltaic Arrays

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.; Scheiman, David A.; Hoffman, David J.

    1998-01-01

    Spacecraft photovoltaic arrays (PVA's) must be carefully handled during ground integration processing and transportation to the launch site. Care is exercised to avoid damage that could degrade on-orbit electrical performance. Because of this damage risk, however, PVA's are typically deployed and illuminated with a light source so performance characteristics can be measured prior to launch. For large-area arrays, such as the Mir Cooperative Solar Array (2.7- by 18-m) and the International Space Station PVA blankets (4.6- by 31.7-m), this integrity check becomes resource intensive. Large test support structures are needed to offload the array during deployment in 1g, and large-aperture illumination equipment is required to uniformly illuminate array panels. Significant program time, funds, and manpower must be allocated for this kind of test program. Alternatively, launch site electrical performance tests can be bypassed with an attendant increase in risk.

  16. Optical activities of large-area SU8 microspirals fabricated by multibeam holographic lithography.

    PubMed

    Wang, Xia; Gao, Wensheng; Hung, Jenny; Tam, Wing Yim

    2014-04-10

    We report on the fabrication of large-area microspirals in SU8 photoresist using a 6+1 beam holographic lithography (HL) technique involving the interference of six linearly polarized side beams and one circularly polarized central beam. In contrast to common photoresist-substrate (glass) configuration, the spirals are fabricated on a substrate with a precured thin SU8 photoresist. This SU8-SU8-glass configuration strengthens the attachment of the spirals to the substrate, and hence enhances the quality of the fabricated spirals. The fabricated SU8 microspirals exhibit large optical activities with a polarization rotation close to 10 deg and a circular dichroism of about 0.5 in the visible range. Our precured substrate method could lift the limitations of the HL method in fabricating large and uniform microstructures or nanostructures.

  17. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  18. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  19. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  20. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  1. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  2. The design and application of large area intensive lens array focal spots measurement system

    NASA Astrophysics Data System (ADS)

    Chen, Bingzhen; Yao, Shun; Yang, Guanghui; Dai, Mingchong; Wang, Zhiyong

    2014-12-01

    Concentrating Photovoltaic (CPV) modules are getting thinner and using smaller cells now days. Correspondingly, large area intensive lens arrays with smaller unit dimension and shorter focal length are wanted. However, the size and power center of lens array focal spots usually differ from the design value and are hard to measure, especially under large area situation. It is because the machining error and deformation of material of the lens array are hard to simulate in the optical design process. Thus the alignment error between solar cells and focal spots in the module assembly process will be hard to control. Under this kind of situation, the efficiency of CPV module with thinner body and smaller cells is much lower than expected. In this paper, a design of large area lens array focal spots automatic measurement system is presented, as well as its prototype application results. In this system, a four-channel parallel light path and its corresponding image capture and process modules are designed. These modules can simulate focal spots under sunlight and have the spots image captured and processed using charge coupled devices and certain gray level algorithm. Thus the important information of focal spots such as spot size and location will be exported. Motion control module based on grating scale signal and interval measurement method are also employed in this system in order to get test results with high speed and high precision on large area lens array no less than 1m×0.8m. The repeatability of the system prototype measurement is +/-10μm with a velocity of 90 spot/min. Compared to the original module assembled using coordinates from optical design, modules assembled using data exported from the prototype is 18% higher in output power, reaching a conversion efficiency of over 31%. This system and its design can be used in the focal spot measurement of planoconvex lens array and Fresnel lens array, as well as other kinds of large area lens array application

  3. Characterization of the large area plane-symmetric low-pressure DC glow discharge

    NASA Astrophysics Data System (ADS)

    Avtaeva, S.; Gorokhovsky, V.; Myers, S.; Robertson, S.; Shunko, E.; Zembower, Z.

    2016-10-01

    Electron density and temperature as well as nitrogen dissociation degree in the low-pressure (10-50 mTorr) large area plane-symmetric DC glow discharge in Ar-N2 mixtures are studied by probes and spectral methods. Electron density measured by a hairpin probe is in good agreement with that derived from the intensity ratio of the N2 2nd positive system bands IC , 1 - 3/IC , 0 - 2 and from the intensity ratio of argon ions and atom lines IArII/IArI, while Langmuir probe data provides slightly higher values of electron density. Electron density in the low-pressure DC glow discharge varies with the discharge conditions in the limits of 108-1010 cm- 3. The concept of electron temperature can be used in low-pressure glow discharges with reservations. The intensity ratio of (0-0) vibrational bands of N2 1st negative and 2nd positive systems I391.4/I337.1 exhibits the electron temperature of 1.5-2.5 eV when argon fraction in the mixture is higher than nitrogen fraction and this ratio quickly increases with nitrogen fraction up to 10 eV in pure nitrogen. The electron temperature calculated from Langmuir probe I-V characteristics assuming a Maxwellian EEDF, gives Te 0.3-0.4 eV. In-depth analysis of the EEDF using the second derivative of Langmuir probe I-V characteristics shows that in a low-pressure glow discharge the EEDF is non-Maxwellian. The EEDF has two populations of electrons: the main background non-Maxwellian population of ;cold; electrons with the mean electron energy of 0.3-0.4 eV and the small Maxwellian population of ;hot; electrons with the mean electron energy of 1.0-2.5 eV. Estimations show that with electron temperature lower than 1 eV the rate of the direct electron impact ionization of N2 is low and the main mechanism of N2 ionization becomes most likely Penning and associative ionization. In this case, assumptions of the intensity ratio IN2+ , 391/IN2 , 337 method are violated. In the glow discharge, N2 dissociation degree reaches about 7% with the argon

  4. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition.

    PubMed

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-10

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm(2)) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  5. Flight Qualification And Production Results With Large Area Space Solar Cells And Panel Assembly

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Hanley, James; Jun, Bogim; Bardfield, Rina; Stone, Beth

    2011-10-01

    Spectrolab's product roadmap provides improvement in product performance in parallel with continuous cost reduction to maintain competitive standing in our industry. Product performance improvement is achieved by developing higher efficiency solar cells (e.g. 29.5% XTJ and 33% IMM cells).Reduced product cost is achieved historically through a variety of means including yield improvements, direct material cost reductions, process changes, and most recently, a transition to large area cell configurations (e.g. "LEONE" at 59.65 cm2). Spectrolab has successfully completed the qualification of its latest triple junction space solar cell, the 29.5% 2 XTJ (26.62 cm ), per AIAA-S-111-2005 - augmented by additional Spectrolab testing. Large area LEONE UTJ and XTJ cells (59.65 cm2 from 100 mm diameter germanium wafer) have also been qualified. Use of these large area cells has resulted in the reduction of solar panel cost, add-on mass and manufacturing cycle time for programs. This evolution to larger area cells is the result of a strategic cost reduction effort initiated in 2006; the first step of which was to manufacture the largest possible cells (LEONE) using the 100 mm germanium (Ge) wafer. In flight production since 2007, the LEONE UTJ cell has now completed rigorous qualification testing to 15,549 GEO (Geosynchronous orbit) and 66,060 LEO (Low Earth Orbit) thermal cycles. Over 53,000 LEONE UTJ cells, including more than 27,000 cells on panels delivered to flight programs, have been produced to date. The on-orbit performance of the LEONE UTJ cells is nominal. Finally, progress on the second step of our strategic cost reduction effort towards larger cells and less piece part handling is presented. This effort involves the establishment of a 150 mm Ge -based manufacturing infrastructure.

  6. Sensing sheets based on large area electronics for fatigue crack detection

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Glisic, Branko

    2015-03-01

    Reliable early-stage damage detection requires continuous structural health monitoring (SHM) over large areas of structure, and with high spatial resolution of sensors. This paper presents the development stage of prototype strain sensing sheets based on Large Area Electronics (LAE), in which thin-film strain gauges and control circuits are integrated on the flexible electronics and deposited on a polyimide sheet that can cover large areas. These sensing sheets were applied for fatigue crack detection on small-scale steel plates. Two types of sensing-sheet interconnects were designed and manufactured, and dense arrays of strain gauge sensors were assembled onto the interconnects. In total, four (two for each design type) strain sensing sheets were created and tested, which were sensitive to strain at virtually every point over the whole sensing sheet area. The sensing sheets were bonded to small-scale steel plates, which had a notch on the boundary so that fatigue cracks could be generated under cyclic loading. The fatigue tests were carried out at the Carleton Laboratory of Columbia University, and the steel plates were attached through a fixture to the loading machine that applied cyclic fatigue load. Fatigue cracks then occurred and propagated across the steel plates, leading to the failure of these test samples. The strain sensor that was close to the notch successfully detected the initialization of fatigue crack and localized the damage on the plate. The strain sensor that was away from the crack successfully detected the propagation of fatigue crack based on the time history of measured strain. Overall, the results of the fatigue tests validated general principles of the strain sensing sheets for crack detection.

  7. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-01

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm2) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  8. The characteristics of solar wind magnetic field during the negative-AU and large-AU (>1200nT) events

    NASA Astrophysics Data System (ADS)

    Lyu, L. H.; Kao, W.

    2014-12-01

    The negative-AU events are relatively unusual, which have caught our attention. To understand the cause of negative AU, we first eliminate the ring-current effect by considering only the events with AUnegative Bz and By components during these negative-AU events. We also found that one of the negative AU events has been reported by Feldstein et al. (2006). They associated the enhancement of westward electric jet by the negative IMF-By component based on previous models obtained independently by Friis-Christensen et al. (1972) and Sumaruk & Feldstein (1973). Enhancement of electric jet in opposite direction is expected to be found when the IMF-By is positive. To verify their models we also examine the strong AU events with AU > 1200nT. We found that these large-AU events are associated with IMF-Bz<0 and IMF-By >0. Both negative-AU and large-AU events tend to occur during the beginning of the main phase of a strong magnetic storm with Kp= 7~9. The enhancement of Cowling electrojet has been proposed by Kan et al. (2011) for the triggering of substorm onset. We will discuss the possibility that a similar enhancement process might take place in the dayside auroral oval during these extreme AU events.

  9. Continued improvment of large area, in situ sputter deposition of superconducting YBCO thin films

    NASA Technical Reports Server (NTRS)

    Truman, J. K.; White, W. R.; Ballentine, P. H.; Mallory, D. S.; Kadin, A. M.

    1993-01-01

    The deposition of thin films of superconducting YBa2Cu3O7-x onto substrates of up to 3-in diameter by an integrated off-axis sputtering is reported. The substrate is located above the center of an 8-in-diameter YBCO planar target, and, in conjunction with a negative ion shield, negative ion effects are avoided. A large radiant heater provides backside, noncontact heating of the bare substrates. YBCO films have been grown on polished 1-cm2 MgO and LaAlO3 substrates with Tc = 90 K or greater, Jc = 2.5 x 10 exp 6 A/sq cm or greater at 77 K, and microwave surface resistance Rs less than 0.4 micro-ohm at 77 K and 10 GHz. The films have a very smooth surface morphology. Uniformity data for LaAlO3 substrates are less than +/-5 percent in Rs. Thickness uniformity results for 3-in substrates indicate less than 10 percent variation. The growth of epitaxial insulating films for use with YBCO films and application of the YBCO films in microwave devices are briefly discussed.

  10. Toward large-area sub-arcsecond x-ray telescopes II

    NASA Astrophysics Data System (ADS)

    O'Dell, Stephen L.; Allured, Ryan; Ames, Andrew O.; Biskach, Michael P.; Broadway, David M.; Bruni, Ricardo J.; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Chung, Yip-Wah; Cotroneo, Vincenzo; Elsner, Ronald F.; Gaskin, Jessica A.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Hertz, Edward; Jackson, Thomas N.; Kilaru, Kiranmayee; Kolodziejczak, Jeffrey J.; McClelland, Ryan S.; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Romaine, Suzanne E.; Saha, Timo T.; Schattenburg, Mark L.; Schwartz, Daniel A.; Schwartz, Eric D.; Solly, Peter M.; Trolier-McKinstry, Susan; Ulmer, Melville P.; Vikhlinin, Alexey; Wallace, Margeaux L.; Wang, Xiaoli; Windt, David L.; Yao, Youwei; Ye, Shi; Zhang, William W.; Zuo, Heng

    2016-09-01

    In order to advance significantly scientific objectives, future x-ray astronomy missions will likely call for x-ray telescopes with large aperture areas (≍ 3 m2) and fine angular resolution (≍ 12). Achieving such performance is programmatically and technologically challenging due to the mass and envelope constraints of space-borne telescopes and to the need for densely nested grazing-incidence optics. Such an x-ray telescope will require precision fabrication, alignment, mounting, and assembly of large areas (≍ 600 m2) of lightweight (≍ 2 kg/m2 areal density) high-quality mirrors, at an acceptable cost (≍ 1 M$/m2 of mirror surface area). This paper reviews relevant programmatic and technological issues, as well as possible approaches for addressing these issues-including direct fabrication of monocrystalline silicon mirrors, active (in-space adjustable) figure correction of replicated mirrors, static post-fabrication correction using ion implantation, differential erosion or deposition, and coating-stress manipulation of thin substrates.

  11. Fabrication of a Horizontal and a Vertical Large Surface Area Nanogap Electrochemical Sensor

    PubMed Central

    Hammond, Jules L.; Rosamond, Mark C.; Sivaraya, Siva; Marken, Frank; Estrela, Pedro

    2016-01-01

    Nanogap sensors have a wide range of applications as they can provide accurate direct detection of biomolecules through impedimetric or amperometric signals. Signal response from nanogap sensors is dependent on both the electrode spacing and surface area. However, creating large surface area nanogap sensors presents several challenges during fabrication. We show two different approaches to achieve both horizontal and vertical coplanar nanogap geometries. In the first method we use electron-beam lithography (EBL) to pattern an 11 mm long serpentine nanogap (215 nm) between two electrodes. For the second method we use inductively-coupled plasma (ICP) reactive ion etching (RIE) to create a channel in a silicon substrate, optically pattern a buried 1.0 mm × 1.5 mm electrode before anodically bonding a second identical electrode, patterned on glass, directly above. The devices have a wide range of applicability in different sensing techniques with the large area nanogaps presenting advantages over other devices of the same family. As a case study we explore the detection of peptide nucleic acid (PNA)−DNA binding events using dielectric spectroscopy with the horizontal coplanar device. PMID:27983655

  12. GLAST LARGE AREA TELESCOPE: DAILY SURVEY OF HIGH-ENERGY SKY

    SciTech Connect

    Kamae, T

    2003-12-12

    GLAST Large Area Telescope was proposed to NASA in 1999 as follow-up of EGRET on-board Compton Gamma-Ray Observatory by an international collaboration. The proposal has been approved as a part of the GLAST observatory mission in its capability to explore w die range of astrophysics with 5-40 times higher sensitivity and extended energy coverage (20 MeV to 300 GeV) than EGRET. The instrument consists of 16 towers of e{sup +}e{sup -} pair tracker, 16 blocks of segmented electro-magnetic calorimeter, and a st of anti-coincidence plastic scintillator tiles covering the tracker towers. It will have 5-10 times larger on-axis effective area, 6 times wider field-of-view (FOV), and up to 5 times better angular resolution when compared with EGRET. The Large Area Telescope will cover about 40% of the sky above the Earth's horizon in its FOV at any given time and will scan nearly the entire Universe every orbit ({approx} 90min): about 20% of Gamma-Ray Bursts will be observed from the onset of the bursts to the initial after-glow phase; all longer-lasting transients and variabilities will be detected daily at the improved sensitivity.

  13. Toward Large-Area Sub-Arcsecond X-Ray Telescopes II

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Allured, Ryan; Ames, Andrew O.; Biskach, Michael P.; Broadway David M.; Bruni, Ricardo J.; Burrows, David; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Chung, Yip-Wah; Cotroneo, Vincenzo; Elsner, Ronald F.; Gaskin, Jessica A.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Hertz, Edward; Jackson, Thomas N.; Kilaru, Kiranmayee; Kolodziejczak, Jeffery J.; McClelland, Ryan S.; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Romaine, Suzanne E.; Saha, Timo T.; Schattenburg, Mark L.; Schwartz, Daniel A.; Schwartz, Eric D.; Solly, Peter M.; Trolier-McKinstry, Susan E.; Ulmer, Mellville P.; Vikhlilin, Alexey; Wallace, Margeaux L.; Zhang, William W.

    2016-01-01

    In order to advance significantly scientific objectives, future x-ray astronomy missions will likely call for x-ray telescopes with large aperture areas (approx. = 3 sq m) and fine angular resolution (approx. = 1"). Achieving such performance is programmatically and technologically challenging due to the mass and envelope constraints of space-borne telescopes and to the need for densely nested grazing-incidence optics. Such an x-ray telescope will require precision fabrication, alignment, mounting, and assembly of large areas (approx. = 600 sq m) of lightweight (approx. = 2 kg/sq m areal density) high-quality mirrors, at an acceptable cost (approx. = 1 M$/sq m of mirror surface area). This paper reviews relevant programmatic and technological issues, as well as possible approaches for addressing these issues-including direct fabrication of monocrystalline silicon mirrors, active (in-space adjustable) figure correction of replicated mirrors, static post-fabrication correction using ion implantation, differential erosion or deposition, and coating-stress manipulation of thin substrates.

  14. Wearable light management system for light stimulated healing of large area chronic wounds (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kallweit, David; Mayer, Jan; Fricke, Sören; Schnieper, Marc; Ferrini, Rolando

    2016-03-01

    Chronic wounds represent a significant burden to patients, health care professionals, and health care systems, affecting over 40 million patients and creating costs of approximately 40 billion € annually. We will present a medical device for photo-stimulated wound care based on a wearable large area flexible and disposable light management system consisting of a waveguide with incorporated micro- and nanometer scale optical structures for efficient light in-coupling, waveguiding and homogeneous illumination of large area wounds. The working principle of this innovative device is based on the therapeutic effects of visible light to facilitate the self-healing process of chronic wounds. On the one hand, light exposure in the red (656nm) induces growth of keratinocytes and fibroblasts in deeper layers of the skin. On the other hand, blue light (453nm) is known to have antibacterial effects predominately at the surface layers of the skin. In order to be compliant with medical requirements the system will consist of two elements: a disposable wound dressing with embedded flexible optical waveguides for the light management and illumination of the wound area, and a non-disposable compact module containing the light sources, a controller, a rechargeable battery, and a data transmission unit. In particular, we will report on the developed light management system. Finally, as a proof-of-concept, a demonstrator will be presented and its performances will be reported to demonstrate the potential of this innovative device.

  15. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes

    PubMed Central

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-01-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication. PMID:27466010

  16. Inductively coupled plasmas: Optimizing the inductive-coupling efficiency for large-area source design

    SciTech Connect

    Colpo, P.; Meziani, T.; Rossi, F.

    2005-03-01

    An inductively coupled plasma (ICP) source enabling high-density plasma generation was developed for large area processing. Technological difficulties related to the scaling up of the coil antenna, dielectric vacuum window, and gas distribution have been addressed. The proposed solution consists in using a magnetic core to concentrate the magnetic field produced by the antenna. Both are placed within the plasma chamber, and the gas injection is done through the magnetic pole. A 75x72- cm{sup 2} plasma source has been designed based on this solution. First, the electrical operation and coil geometries were optimized. The results show that the use of a low excitation frequency (2 MHz) increases the electrical efficiency of the magnetic core, enabling a higher plasma-density generation than at the classical radio frequency of 13.56 MHz. The antenna configuration providing the better uniformity is composed of three loops connected in parallel. Some tuning inductances in series with each loop were added to balance the rf power, i.e., the plasma density over the reactor area. Deviation from plasma uniformities better than 12% over 60x60 cm{sup 2} were achieved. Preliminary SiO{sub 2} etching experiments with CF{sub 4} gas show that the etching uniformity deviation reaches 7% over 60x60 cm{sup 2} with etching rates larger than 150 nm/min. These results are very promising and open the way to the successful scale-up of ICP sources to large areas.

  17. Self-formation of sub-60-nm half-pitch gratings with large areas through fracturing

    NASA Astrophysics Data System (ADS)

    Pease, Leonard F.; Deshpande, Paru; Wang, Ying; Russel, William B.; Chou, Stephen Y.

    2007-09-01

    Periodic micro- and nanostructures (gratings) have many significant applications in electronic, optical, magnetic, chemical and biological devices and materials. Traditional methods for fabricating gratings by writing with electrons, ions or a mechanical tip are limited to very small areas and suffer from extremely low throughput. Interference lithography can achieve relatively large fabrication areas, but has a low yield for small-period gratings. Photolithography, nanoimprint lithography, soft lithography and lithographically induced self-construction all require a prefabricated mask, and although electrohydrodynamic instabilities can self-produce periodic dots without a mask, gratings remain challenging. Here, we report a new low-cost maskless method to self-generate nano- and microgratings from an initially featureless polymer thin film sandwiched between two relatively rigid flat plates. By simply prising apart the plates, the film fractures into two complementary sets of nonsymmetrical gratings, one on each plate, of the same period. The grating period is always four times the thickness of the glassy film, regardless of its molecular weight and chemical composition. Periods from 120 nm to 200 µm have been demonstrated across areas as large as two square centimetres.

  18. Self-formation of sub-60-nm half-pitch gratings with large areas through fracturing.

    PubMed

    Pease, Leonard F; Deshpande, Paru; Wang, Ying; Russel, William B; Chou, Stephen Y

    2007-09-01

    Periodic micro- and nanostructures (gratings) have many significant applications in electronic, optical, magnetic, chemical and biological devices and materials. Traditional methods for fabricating gratings by writing with electrons, ions or a mechanical tip are limited to very small areas and suffer from extremely low throughput. Interference lithography can achieve relatively large fabrication areas, but has a low yield for small-period gratings. Photolithography, nanoimprint lithography, soft lithography and lithographically induced self-construction all require a prefabricated mask, and although electrohydrodynamic instabilities can self-produce periodic dots without a mask, gratings remain challenging. Here, we report a new low-cost maskless method to self-generate nano- and microgratings from an initially featureless polymer thin film sandwiched between two relatively rigid flat plates. By simply prising apart the plates, the film fractures into two complementary sets of nonsymmetrical gratings, one on each plate, of the same period. The grating period is always four times the thickness of the glassy film, regardless of its molecular weight and chemical composition. Periods from 120 nm to 200 microm have been demonstrated across areas as large as two square centimetres.

  19. Substrate-free self-assembly approach toward large-area nanomembranes.

    PubMed

    Wang, Fei; Seo, Jung-Hun; Ma, Zhenqiang; Wang, Xudong

    2012-03-27

    Free-standing two-dimensional nanostrucutures, such as graphene and semiconductor nanomembranes (NMs) featuring their integration with flexible polymer substrates, address applications in which electronic devices need to be stretchable or conformally positioned to nonplanar surfaces. We report a surfactant-directed surface assembly approach to producing large-area NMs at the water-air interface. The NMs were produced by employing the surfactants as templates as well as incorporating them in the crystal structures. By using excess amount of sodium dodecylsulfate (SDS), a tightly packed monolayer of dodecylsulfate (DS) ion was formed and directed the crystallization of submillimeter-sized zinc hydroxy dodecylsulfate (ZHDS) single-crystalline NMs over the entire water surface. This free-standing NM can be readily transferred to an arbitrary substrate and converted to ZnO via heat treatment. A flexible thin-film transistor was also fabricated using the transferred NMs and demonstrated reasonably good n-type transport properties. This approach circumvented the needs of single-crystalline substrates for making large-area NMs from materials that do not possess a laminate structure. It is a low-cost and large-scale synthesis technique and has great potential in developing NMs and flexible devices from various functional materials that are not feasible by conventional selective etching or delamination approaches.

  20. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    PubMed Central

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-01-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis. PMID:27601181

  1. Design and analysis of a modified segmented cladding fiber with large mode area

    NASA Astrophysics Data System (ADS)

    Ma, Shaoshuo; Ning, Tigang; Li, Jing; Zheng, Jingjing; Wen, Xiaodong; Pei, Li

    2017-02-01

    This paper proposes a novel segmented cladding fiber structure for large mode area properties. In this structure a thin ring is placed between the high index core and nonuniform cladding. It is called Single-Ring Segmented-Cladding Fiber (SR-SCF). The novel fiber offers the possibility of single-mode(SM) operation from 1 μm to 1.7 μm with a large core diameter. With illustrations, the fiber has a better SM operation than segmented-cladding fiber (SCF) is demonstrated. A large effective area of 1000 μm2 is achieved. The SM operation with very high suppression of the higher order modes can arise by 76%. Moreover, mode spacing between the adjacent modes (LP01 and LP11) is also improved significantly. Besides, the bending property is analyzed. It is found that the fiber is insensitive to bending angle ranging from -180° to 180° at bending radius of 30 cm. The proposed fiber will play an important role in developing high power fiber laser, fiber amplifier and high power delivery application.

  2. Alternative Patterning Process for Realization of Large-Area, Full-Color, Active Quantum Dot Display.

    PubMed

    Park, Joon-Suh; Kyhm, Jihoon; Kim, Hong Hee; Jeong, Shinyoung; Kang, JoonHyun; Lee, Song-Ee; Lee, Kyu-Tae; Park, Kisun; Barange, Nilesh; Han, JiYeong; Song, Jin Dong; Choi, Won Kook; Han, Il Ki

    2016-11-09

    Although various colloidal quantum dot (QD) coating and patterning techniques have been developed to meet the demands in optoelectronic applications over the past years, each of the previously demonstrated methods has one or more limitations and trade-offs in forming multicolor, high-resolution, or large-area patterns of QDs. In this study, we present an alternative QD patterning technique using conventional photolithography combined with charge-assisted layer-by-layer (LbL) assembly to solve the trade-offs of the traditional patterning processes. From our demonstrations, we show repeatable QD patterning process that allows multicolor QD patterns in both large-area and microscale. Also, we show that the QD patterns are robust against additional photolithography processes and that the thickness of the QD patterns can be controlled at each position. To validate that this process can be applied to actual device applications as an active material, we have fabricated inverted, differently colored, active QD light-emitting device (QD-LED) on a pixelated substrate, which achieved maximum electroluminescence intensity of 23 770 cd/m(2), and discussed the results. From our findings, we believe that our process provides a solution to achieving both high-resolution and large-scale QD pattern applicable to not only display, but also to practical photonic device research and development.

  3. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    NASA Astrophysics Data System (ADS)

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-09-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis.

  4. Power analysis for the design of a large area ultrasonic tactile touch panel

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Lemaire-Semail, Betty; Giraud, Frédéric; Amberg, Michel; Zhang, Yuru; Giraud-Audine, Christophe

    2015-10-01

    Tactile interfaces are intuitive but lack of haptic feedback. One method to provide tactile feedback is to change the friction coefficient of the touch surface. Several small-size tactile devices have been developed to provide programmable friction coefficient based on the squeeze air film effect. This effect is produced by ultrasonic vibration of the tactile plate thanks to piezoceramics. In order to design larger embedded tactile feedback areas, a key issue is the power consumption. In this paper, we present the power analysis of a tactile device which is based on the squeeze film effect. We first investigate the source of power consumption by a series of measurements. Then, an analytical model is developed to estimate the power, which gives the conclusion that, when the vibration amplitude is constant, the power consumption is not related to the number of piezoelectric actuators. According to this result, we design a large area (198 mm × 138 mm) tactile plate with only eight piezoelectric actuators. Experimental results show that the power consumption of the large tactile plate is less than 2 W. Moreover, we also find that the power consumption of the large tactile plate was predictable with the measurement results from small plates with an average error of less than 10%.

  5. Large-area patterned substrates for micromagnetic actuation of superparamagnetic microbeads

    NASA Astrophysics Data System (ADS)

    Ouk, Minae; Beach, Geoffrey

    2014-03-01

    Superparamagnetic microbeads (SBs) are widely used to capture biological entities in a fluid environment. Chip-based magnetic actuation provides a means to transport SBs in lab-on-a-chip technologies. This is usually accomplished using the stray field from patterned magnetic microstructures, or domain walls in magnetic nanowires. However, lithographic patterning over a large area is costly and impractical using conventional techniques such as electron beam lithography. Here we use a simple floating-transfer technique for large-area self-assembly of polystyrene microspheres on a Si wafer to produce lithographic masks texturing a substrate. Hexagonal patterns are used as lift-off and etching masks to create magnetic dot and anti-dot arrays in CoFe thin films, with a size and spacing that can be tuned via sphere diameter and RIE etch time. Using a rotating magnetic fields, we show that these magnetically-patterned substrates can transport SBs across large distances on the wafer surface, opening the possibility to augment or replace microfluidic actuation for long distance transport. Supported by the MIT Deshpande Center.

  6. Influence of transbilayer area asymmetry on the morphology of large unilamellar vesicles.

    PubMed Central

    Mui, B L; Döbereiner, H G; Madden, T D; Cullis, P R

    1995-01-01

    The morphological consequences of differences in the monolayer surface areas of large unilamellar vesicles (LUVs) have been examined employing cryoelectron microscopy techniques. Surface area was varied by inducing net transbilayer transport of dioleoylphosphatidylglycerol (DOPG) in dioleoylphosphatidylcholine (DOPC):DOPG (9:1, mol:mol) LUVs in response to transmembrane pH gradients. It is shown that when DOPG is transported from the inner to the outer monolayer, initially invaginated LUVs are transformed to long narrow tubular structures, or spherical structures with one or more protrusions. Tubular structures are also seen in response to outward DOPG transport in DOPC:DOPG:Chol (6:1:3, mol:mol:mol) LUV systems, and when lyso-PC is allowed to partition into the exterior monolayer of DOPC:DOPG (9:1, mol:mol) LUVs in the absence of DOPG transport. Conversely, when the inner monolayer area is expanded by the transport of DOPG from the outer monolayer to the inner monolayer of non-invaginated LUVs, a reversion to invaginated structures is observed. The morphological changes are well described by an elastic bending theory of the bilayer. Identification of the difference in relaxed monolayer areas and of the volume-to-area ratio of the LUVs as the shape-determining factors allows a quantitative classification of the observed morphologies. The morphology seen in LUVs supports the possibility that factors leading to differences in monolayer surface areas could play important roles in intracellular membrane transport processes. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 PMID:8519993

  7. A strategy for GIS-based 3-D slope stability modelling over large areas

    NASA Astrophysics Data System (ADS)

    Mergili, M.; Marchesini, I.; Alvioli, M.; Metz, M.; Schneider-Muntau, B.; Rossi, M.; Guzzetti, F.

    2014-12-01

    GIS-based deterministic models may be used for landslide susceptibility mapping over large areas. However, such efforts require specific strategies to (i) keep computing time at an acceptable level, and (ii) parameterize the geotechnical data. We test and optimize the performance of the GIS-based, 3-D slope stability model r.slope.stability in terms of computing time and model results. The model was developed as a C- and Python-based raster module of the open source software GRASS GIS and considers the 3-D geometry of the sliding surface. It calculates the factor of safety (FoS) and the probability of slope failure (Pf) for a number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Model input consists of a digital elevation model (DEM), ranges of geotechnical parameter values derived from laboratory tests, and a range of possible soil depths estimated in the field. Probability density functions are exploited to assign Pf to each ellipsoid. The model calculates for each pixel multiple values of FoS and Pf corresponding to different sliding surfaces. The minimum value of FoS and the maximum value of Pf for each pixel give an estimate of the landslide susceptibility in the study area. Optionally, r.slope.stability is able to split the study area into a defined number of tiles, allowing parallel processing of the model on the given area. Focusing on shallow landslides, we show how multi-core processing makes it possible to reduce computing times by a factor larger than 20 in the study area. We further demonstrate how the number of random slip surfaces and the sampling of parameters influence the average value of Pf and the capacity of r.slope.stability to predict the observed patterns of shallow landslides in the 89.5 km2 Collazzone area in Umbria, central Italy.

  8. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin

    2016-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heaters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  9. Thermal Vacuum Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin

    2016-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and to verify its ability to cool large areas or components in the 3 degrees Kelvin temperature range. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by simply applying power to both the capillary pump and the evaporator plate without pre-conditioning. It could adapt to a rapid heat load change and quickly reach a new steady state. Heat removal between 10 megawatts and 140 megawatts was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  10. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  11. GLAST: Exploring Nature's Highest Energy Processes with the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Digel, Seth; Myers, J. D.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is an international and multi-agency space mission that will study the cosmos in the energy range 10 keV-300 GeV. Several successful exploratory missions in gamma-ray astronomy led to the Energetic Gamma Ray Experiment Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). Launched in 1991, EGRET made the first complete survey of the sky in the 30 MeV-10 GeV range. EGRET showed the high-energy gamma-ray sky to be surprisingly dynamic and diverse, with sources ranging from the sun and moon to massive black holes at large redshifts. Most of the gamma-ray sources detected by EGRET remain unidentified. In light of the discoveries with EGRET, the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope vastly more capable than instruments flown previously, as well as a secondary instrument to augment the study of gamma-ray bursts. The main instrument, the Large Area Telescope (LAT), will have superior area, angular resolution, field of view, and deadtime that together will provide a factor of 30 or more advance in sensitivity, as well as provide capability for study of transient phenomena. The GLAST Burst Monitor (GBM) will have a field of view several times larger than the LAT and will provide spectral coverage of gamma-ray bursts that extends from the lower limit of the LAT down to 10 keV. The basic parameters of the GBM are compared to those of the Burst and Transient Source Experiment (BATSE) instrument on CGRO in Table 1-2. With the LAT and GBM, GLAST will be a flexible observatory for investigating the great range of astrophysical phenomena best studied in high-energy gamma rays. NASA plans to launch GLAST in late 2005.

  12. Simulating daily rainfall fields over large areas for collective risk estimation

    NASA Astrophysics Data System (ADS)

    Serinaldi, Francesco; Kilsby, Chris G.

    2014-05-01

    Large scale rainfall models are needed for collective risk estimation in flood insurance, infrastructure networks and water resource management applications. There is a lack of models which can provide simulations over large river basins (potentially multi-national) at appropriate spatial resolution (e.g., 5-25 km) that preserve both the local properties of rainfall (i.e., marginal distributions and temporal correlation) and the spatial structure of the field (i.e., the spatial dependence structure). In this study we describe a methodology which merges meta-Gaussian random fields and generalized additive models to simulate realistic rainfall fields at daily time scale over large areas. Unlike other techniques previously proposed in the literature, the suggested approach does not split the rainfall occurrence and intensity processes and resorts to a unique discrete-continuous distribution to reproduce the local properties of rainfall. This choice allows the use of a unique meta-Gaussian spatio-temporal random field substrate that is devised to reproduce the spatial properties and the short term temporal characteristics of the observed precipitation. The model is calibrated and tested on a 25 km gridded daily rainfall data set covering the 817 000 km2 of the Danube basin. Standard and ad hoc diagnostics highlight the overall good performance over the whole range of rainfall values at multiple scales of spatio-temporal aggregation with particular attention to extreme values. Moreover, the modular structure of the model allows for refinements, adaptation to different areas and the introduction of exogenous forcing variables, thus making it a valuable tool for classical hydrologic analyses as well as for new challenges of network and reinsurance risk assessment over extensive areas.

  13. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2015-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  14. Evidence for large-area superemission into a high-current glow discharge

    NASA Astrophysics Data System (ADS)

    Hartmann, W.; Dominic, V.; Kirkman, G. F.; Gundersen, M. A.

    1988-10-01

    This letter presents evidence for large-area (≊1 cm2) cathode superemission (˜10 000 A/cm2) into a high-current glow discharge in a pseudospark or back lighted thyratron switch. Cathodes studied with a scannning electron microscope following operation at 6-8 kA, ≊1 μs pulse length, and 105 pulses in a low-pressure H2 discharge show evidence of melting of a thin surface layer within a radius of ˜4 mm, indicating that the discharge is a superdense glow with a cross-sectional area of the order of 1 cm2, rather than an arc. Further supporting evidence is provided by streak camera data. An ion beam present during the avalanche phase of the discharge is responsible for heating the cathode surface resulting in a significant field-enhanced thermionic emission.

  15. Versatile large-mode-area femtosecond laser-written Tm:ZBLAN glass chip lasers.

    PubMed

    Lancaster, D G; Gross, S; Fuerbach, A; Heidepriem, H Ebendorff; Monro, T M; Withford, M J

    2012-12-03

    We report performance characteristics of a thulium doped ZBLAN waveguide laser that supports the largest fundamental modes reported in a rare-earth doped planar waveguide laser (to the best of our knowledge). The high mode quality of waveguides up to 45 um diameter (~1075 μm(2) mode-field area) is validated by a measured beam quality of M(2)~1.1 ± 0.1. Benefits of these large mode-areas are demonstrated by achieving 1.9 kW peak-power output Q-switched pulses. The 1.89 μm free-running cw laser produces 205 mW and achieves a 67% internal slope efficiency corresponding to a quantum efficiency of 161%. The 9 mm long planar chip developed for concept demonstration is rapidly fabricated by single-step optical processing, contains 15 depressed-cladding waveguides, and can operate in semi-monolithic or external cavity laser configurations.

  16. Extending single mode performance of all-solid large-mode-area single trench fiber.

    PubMed

    Jain, D; Jung, Y; Nunez-Velazquez, M; Sahu, J K

    2014-12-15

    We report a novel "single trench fiber" design for mode area scaling of the fundamental mode while offering effective single mode operation for a compact fiber laser device. This fiber design allows very high suppression of the higher order modes by offering high loss and power delocalization. It has the advantages of low cost and easy fabrication thanks to all solid fiber design, cylindrical symmetry, and higher refractive index of core as that of the cladding. A Yb-doped single trench fiber with a 40 µm core diameter has been fabricated from modified chemical vapor deposition process in conjunction with solution-doping offering an effective mode area of as large as ~1,000 µm(2) at 1,060 nm for the bend radius of 20 cm. Detailed characterizations confirm a robust single mode behavior of the fiber. Comparative analysis with other fiber designs shows significant performance enhancement of effective single mode operation suitable for fiber laser applications.

  17. Stitching for a large area of surface topography analysis of diamond grinding wheel

    NASA Astrophysics Data System (ADS)

    Wang, Shuang; Cui, Changcai; Huang, Chunqi; Huang, Hui; Ye, Ruifang; Fu, Shiwei

    2013-01-01

    It is necessary to stitch small area of images together for large surface analysis while the measurement instrument used with a limited measurement area, e.g. White-light Interferometry (WLI)-based system. A new stitching method is proposed in this paper for diamond grinding wheel surface analysis. The images are captured by a WLI-based system and the 3D images' stitching requires an overlapping region of 30%~50%. First, two-step intensity correlation matching method is used to obtain several pairs of matched points fast and the RANSAC (Random Sample Consensus) algorithm is adopted to screen them to get exact pairs of matched points. Then the measurement errors are adjusted and a stitched topography is got after data fusion. Experiments show that this method can effectively stitch 3D images of diamond grinding wheel together in less than 4 minutes with a correlation coefficient above 0.9 for two horizontal overlapping regions after adjustment.

  18. Large-area, uniform white light LED source on a flexible substrate.

    PubMed

    Sher, Chin-Wei; Chen, Kuo-Ju; Lin, Chien-Chung; Han, Hau-Vei; Lin, Huang-Yu; Tu, Zong-Yi; Tu, Hsien-Hao; Honjo, Keiji; Jiang, Hsin-Yi; Ou, Sin-Liang; Horng, Ray-Hua; Li, Xiuling; Fu, Chien-Chung; Kuo, Hao-Chung

    2015-09-21

    This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications.

  19. Filtration of coal flotation tailings on large-area filter presses

    SciTech Connect

    Zaslavskii, B.G.; Gaintseva, R.A.; Bruk, O.L.; Komissarenko, N.N.; Safonov, A.S.; Elishevich, A.T.

    1981-01-01

    The environmental conservation problems for coal cleaning plants concern the handling of flotation tailings; they should no longer be discharged into external sludge ponds but rather be converted into a cake suitable for dumping. The most dependable method of conditioning flotation tailings is the dewatering on filter presses; the most popular type, FPAKM-25U, is a vertical filter press of limited throughput capacity. During 1976 to 1979, a filtration section was set up at the Kal'miusskaya Central Washery (P/O Donetskugleobogashchenie) consisting of 4 (subsequently 5) large-area filter presses from Poland (type PF-ROW-1/576, filtration surface area 576 m/sup 2/. The new method of dewatering flotation tailings under pressure in filter presses is less costly than the traditional method of constructing expensive sludge ponds and the necessary pumping facilities and pipework. The saving at the Kal'miusskaya Central Washery is estimated at approx. 250,000 roubles/year.

  20. Large-area few-layer MoS2 deposited by sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Jyun-Hong; Chen, Hsing-Hung; Liu, Pang-Shiuan; Lu, Li-Syuan; Wu, Chien-Ting; Chou, Cheng-Tung; Lee, Yao-Jen; Li, Lain-Jong; Chang, Wen-Hao; Hou, Tuo-Hung

    2016-06-01

    Direct magnetron sputtering of transition metal dichalcogenide targets is proposed as a new approach for depositing large-area two-dimensional layered materials. Bilayer to few-layer MoS2 deposited by magnetron sputtering followed by post-deposition annealing shows superior area scalability over 20 cm2 and layer-by-layer controllability. High crystallinity of layered MoS2 was confirmed by Raman, photo-luminescence, and transmission electron microscopy analysis. The sputtering temperature and annealing ambience were found to play an important role in the film quality. The top-gate field-effect transistor by using the layered MoS2 channel shows typical n-type characteristics with a current on/off ratio of approximately 104. The relatively low mobility is attributed to the small grain size of 0.1-1 μm with a trap charge density in grain boundaries of the order of 1013 cm-2.

  1. Low-impedance internal linear inductive antenna for large-area flat panel display plasma processing

    SciTech Connect

    Kim, K.N.; Jung, S.J.; Lee, Y.J.; Yeom, G.Y.; Lee, S.H.; Lee, J.K.

    2005-03-15

    An internal-type linear inductive antenna, that is, a double-comb-type antenna, was developed for a large-area plasma source having the size of 1020 mmx830 mm, and high density plasmas on the order of 2.3x10{sup 11} cm{sup -3} were obtained with 15 mTorr Ar at 5000 W of inductive power with good plasma stability. This is higher than that for the conventional serpentine-type antenna, possibly due to the low impedance, resulting in high efficiency of power transfer for the double-comb antenna type. In addition, due to the remarkable reduction of the antenna length, a plasma uniformity of less than 8% was obtained within the substrate area of 880 mmx660 mm at 5000 W without having a standing-wave effect.

  2. A large area cosmic muon detector located at Ohya stone mine

    NASA Technical Reports Server (NTRS)

    Nii, N.; Mizutani, K.; Aoki, T.; Kitamura, T.; Mitsui, K.; Matsuno, S.; Muraki, Y.; Ohashi, Y.; Okada, A.; Kamiya, Y.

    1985-01-01

    The chemical composition of the primary cosmic rays between 10 to the 15th power eV and 10 to the 18th power eV were determined by a Large Area Cosmic Muon Detector located at Ohya stone mine. The experimental aims of Ohya project are; (1) search for the ultra high-energy gamma-rays; (2) search for the GUT monopole created by Big Bang; and (3) search for the muon bundle. A large number of muon chambers were installed at the shallow underground near Nikko (approx. 100 Km north of Tokyo, situated at Ohya-town, Utsunomiya-city). At the surface of the mine, very fast 100 channel scintillation counters were equipped in order to measure the direction of air showers. These air shower arrays were operated at the same time, together with the underground muon chamber.

  3. Evapotranspiration and runoff from large land areas: Land surface hydrology for atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Famiglietti, J. S.; Wood, Eric F.

    1993-01-01

    A land surface hydrology parameterization for use in atmospheric GCM's is presented. The parameterization incorporates subgrid scale variability in topography, soils, soil moisture and precipitation. The framework of the model is the statistical distribution of a topography-soils index, which controls the local water balance fluxes, and is therefore taken to represent the large land area. Spatially variable water balance fluxes are integrated with respect to the topography-soils index to yield our large topography-soils distribution, and interval responses are weighted by the probability of occurrence of the interval. Grid square averaged land surface fluxes result. The model functions independently as a macroscale water balance model. Runoff ratio and evapotranspiration efficiency parameterizations are derived and are shown to depend on the spatial variability of the above mentioned properties and processes, as well as the dynamics of land surface-atmosphere interactions.

  4. Novel Low-Bend Large Effective Area Fiber for Fiber-to-the-Home Application

    NASA Astrophysics Data System (ADS)

    Rostami, A.; Makouei, S.

    2011-01-01

    In this article, with sophisticated modification on modal field distribution and introducing a new design procedure, a single-mode fiber with ultra-low bending loss and large effective area (Aeff) that is appropriate for a fiber-to-the-home operation is presented. The bending loss optimization procedure is based on the genetic algorithm. The most remarkable feature of this methodology is designing a bend-insensitive fiber without reduction of core radius and mode field diameter. The designed structure exhibits very small bending loss and large Aeff simultaneously. Simulation results show bending loss of 2.7 × 10-3 dB at 1.55 μm for a single turn of 5-mm radius. The calculated mode field diameter and Aeff for the designed structure are 9.00 μm and 63.62 μm2, respectively.

  5. Measurement of the cosmic-ray proton spectrum with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Green, David; Fermi LAT Area Telescope Collaboration Collaboration

    2017-01-01

    We present the measurement of the cosmic-ray proton spectrum between 54 GeV and 9.5 TeV using 7 years of Pass 8 flight data from the Fermi Large Area Telescope (LAT). We developed a dedicated proton event selection with an acceptance of 0.25 m2 sr. Our analysis yields a large dataset with low statistical uncertainty and low residual contamination for a spectral measurement. The systematic errors associated with the acceptance, energy measurement, GEANT4 Monte-Carlo simulations are an order of magnitude larger than the statistical uncertainty. The event selection and spectral measurement of the proton analysis create the opportunity for additional proton analyses with the LAT, such as a dedicated proton anisotropy search.

  6. An advanced open-path atmospheric pollution monitor for large areas

    SciTech Connect

    Taylor, L.

    1995-10-01

    Large amounts of toxic waste materials, generated in manufacturing fuel for nuclear reactors, are stored in tanks buried over large areas at DOE sites. Flammable and hazardous gases are continually generated by chemical reactions in the waste materials. To prevent explosive concentrations of these gases, the gases are automatically vented to the atmosphere when the pressure exceeds a preset value. Real-time monitoring of the atmosphere above the tanks with automatic alarming is needed to prevent exposing workers to unsafe conditions when venting occurs. This report describes the development of a monitor which can measure concentrations of hazardous gases over ranges as long as 4km. The system consists of a carbon dioxide laser combined with an acousto-optic tunable filter.

  7. Replication fidelity assessment of large area sub-μm structured polymer surfaces using scatterometry

    NASA Astrophysics Data System (ADS)

    Calaon, M.; Madsen, M. H.; Weirich, J.; Hansen, H. N.; Tosello, G.; Hansen, P. E.; Garnaes, J.; Tang, P. T.

    2015-12-01

    The present study addresses one of the key challenges in the product quality control of transparent structured polymer substrates, the replication fidelity of sub-μm structures over a large area. Additionally the work contributes to the development of new techniques focused on in-line characterization of large nanostructured surfaces using scatterometry. In particular an approach to quantify the replication fidelity of high volume manufacturing processes such as polymer injection moulding is presented. Both periodic channels and semi-spherical structures were fabricated on nickel shims used for later injection moulding of Cyclic-olefin-copolymer (COC) substrate were the sub-μm features where ultimately transferred. The scatterometry system was validated using calibrated atomic force microscopy measurements and a model based on scalar diffraction theory employed to calculate the expected angular distribution of the reflected and the transmitted intensity for the nickel surfaces and structured COC and, respectively.

  8. The Gamma-ray Large Area Space Telescope (GLAST): Status and Plans

    NASA Technical Reports Server (NTRS)

    Ritz, Steve

    2008-01-01

    The Gamma-ray Large Area Space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view makes it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its recent launch on 11 June, GLAST now opens a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts: the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations. In addition to the science opportunities, this talk includes a description of the instruments and the mission status and plans.

  9. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    SciTech Connect

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; G. Gettelfinger; T. Gray; D. Hoffman; S. Jardin; H. Kugel; P. Marfuta; T. Munsat; C. Neumeyer; S. Raftopoulos; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; L. Delgado-Aparicio; R.P. Seraydarian; G. Antar; R. Doerner; S. Luckhardt; M. Baldwin; R.W. Conn; R. Maingi; M. Menon; R. Causey; D. Buchenauer; M. Ulrickson; B. Jones; D. Rodgers

    2004-06-07

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  10. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    SciTech Connect

    Kaita, R; Jajeski, R; Boaz, M; Efthimion, P; Gettelfinger, G; Gray, T; Hoffman, D; Jardin, S; Kugel, H; Marfuta, P; Munsat, T; Neumeyer, C; Raftopoulos, S; Soukhanovskii, V; Spaleta, J; Taylor, G; Timberlake, J; Woolley, R; Zakharov, L; Finkenthal, M; Stutman, D; Delgado-Aparicio, L; Seraydarian, R; Antar, G; Doerner, R; Luckhardt, S; Baldwin, M; Conn, R; Maingi, R; Menon, M; Causey, R; Buchenauer, D; Ulrickson, M; Jones, B; Rodgers, D

    2004-06-03

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  11. The large-area hybrid-optics RICH detector for the CLAS12 spectrometer

    DOE PAGES

    Mirazita, M.; Angelini, G.; Balossino, I.; ...

    2017-01-16

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forwardmore » tracks) or after two mirror reflections (large angle tracks). Finally, the preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.« less

  12. Characterization and stabilising dynamic phase fluctuations in large mode area fibres

    NASA Astrophysics Data System (ADS)

    Jones, D. C.; Scott, A. M.

    2007-02-01

    Fibre amplifiers exhibit rapid time dependent phase fluctuations due to the environment and to thermal and other effects associated with the pumping and lasing processes. We characterise these effects in a large mode area fibre amplifier having an output power of 260W limited only by pump power. The amplifier retains its coherence even at the highest available output power with negligible linewidth broadening. Phase fluctuations are characterised by a low-amplitude power-independent jitter superimposed on a power-dependent drift due to heating. We also measure the phase fluctuations in a COTS fibre preamplifier and find they are predominantly large amplitude periodic oscillations at 110Hz, probably induced by pump power fluctuations. The two amplifiers were combined in series to give a high gain amplifier chain and actively phase stabilised to high precision (~λ/37 rms) using a piezo-ceramic fibre stretcher incorporated into a PC-based feedback loop.

  13. Large-area functionalized CVD graphene for work function matched transparent electrodes

    NASA Astrophysics Data System (ADS)

    Bointon, Thomas H.; Jones, Gareth F.; de Sanctis, Adolfo; Hill-Pearce, Ruth; Craciun, Monica F.; Russo, Saverio

    2015-11-01

    The efficiency of flexible photovoltaic and organic light emitting devices is heavily dependent on the availability of flexible and transparent conductors with at least a similar workfunction to that of Indium Tin Oxide. Here we present the first study of the work function of large area (up to 9 cm2) FeCl3 intercalated graphene grown by chemical vapour deposition on Nickel, and demonstrate values as large as 5.1 eV. Upon intercalation, a charge density per graphene layer of 5 ṡ 1013 ± 5 ṡ 1012 cm-2 is attained, making this material an attractive platform for the study of plasmonic excitations in the infrared wavelength spectrum of interest to the telecommunication industry. Finally, we demonstrate the potential of this material for flexible electronics in a transparent circuit on a polyethylene naphthalate substrate.

  14. Health impacts of large releases of radionuclides. The fate and impact of radiocontaminants in urban areas.

    PubMed

    Roed, J; Andersson, K G; Lange, C

    1997-01-01

    The Chernobyl accident made it clear that the contaminants released after a severe nuclear accident may spread over large areas, and thereby form a significant external radiation hazard in areas of high population density. Since then, the weathering effects on the deposited radiocontaminants (essentially radiocaesium) have been followed on different types of surface in urban, suburban and industrial areas in order to enable an estimation of the long-term impact of such events. Analytical expressions have been derived for the typical behaviour of radiocaesium on the different surfaces, and dose measurements and calculations for different urban environments have pinpointed which surfaces generally contribute most to the dose and consequently are most important to clean. At this point, after nearly a decade, the dose rate from horizontal pavements has decreased by at least a factor of 10, whereas the dose rate from an area of soil or a roof has generally only been halved. The contamination on walls is the most persistent: it has only decreased by 10-20%.

  15. Fabrication of dense wavelength division multiplexing filters with large useful area

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Chung; Chen, Sheng-Hui; Hsu, Jin-Cherng; Kuo, Chien-Cheng

    2006-08-01

    Dense Wavelength Division Multiplexers (DWDM), a kind of narrow band-pass filter, are extremely sensitive to the optical thickness error in each composite layer. Therefore to have a large useful coating area is extreme difficult because of the uniformity problem. To enlarge the useful coating area it is necessary to improve their design and their fabrication. In this study, we discuss how the tooling factors at different positions and for different materials are related to the optical performance of the design. 100GHz DWDM filters were fabricated by E-gun evaporation with ion-assisted deposition (IAD). To improve the coating uniformity, an analysis technique called shaping tooling factor (STF) was used to analyze the deviation of the optical thickness in different materials so as to enlarge the useful coating area. Also a technique of etching the deposited layers with oxygen ions was introduced. When the above techniques were applied in the fabrication of 100 GHz DWDM filters, the uniformity was better than +/-0.002% over an area of 72 mm in diameter and better than +/-0.0006% over 20mm in diameter.

  16. Long-period ocean-bottom motions in the source areas of large subduction earthquakes

    PubMed Central

    Nakamura, Takeshi; Takenaka, Hiroshi; Okamoto, Taro; Ohori, Michihiro; Tsuboi, Seiji

    2015-01-01

    Long-period ground motions in plain and basin areas on land can cause large-scale, severe damage to structures and buildings and have been widely investigated for disaster prevention and mitigation. However, such motions in ocean-bottom areas are poorly studied because of their relative insignificance in uninhabited areas and the lack of ocean-bottom strong-motion data. Here, we report on evidence for the development of long-period (10–20 s) motions using deep ocean-bottom data. The waveforms and spectrograms demonstrate prolonged and amplified motions that are inconsistent with attenuation patterns of ground motions on land. Simulated waveforms reproducing observed ocean-bottom data demonstrate substantial contributions of thick low-velocity sediment layers to development of these motions. This development, which could affect magnitude estimates and finite fault slip modelling because of its critical period ranges on their estimations, may be common in the source areas of subduction earthquakes where thick, low-velocity sediment layers are present. PMID:26617193

  17. Long-period ocean-bottom motions in the source areas of large subduction earthquakes.

    PubMed

    Nakamura, Takeshi; Takenaka, Hiroshi; Okamoto, Taro; Ohori, Michihiro; Tsuboi, Seiji

    2015-11-30

    Long-period ground motions in plain and basin areas on land can cause large-scale, severe damage to structures and buildings and have been widely investigated for disaster prevention and mitigation. However, such motions in ocean-bottom areas are poorly studied because of their relative insignificance in uninhabited areas and the lack of ocean-bottom strong-motion data. Here, we report on evidence for the development of long-period (10-20 s) motions using deep ocean-bottom data. The waveforms and spectrograms demonstrate prolonged and amplified motions that are inconsistent with attenuation patterns of ground motions on land. Simulated waveforms reproducing observed ocean-bottom data demonstrate substantial contributions of thick low-velocity sediment layers to development of these motions. This development, which could affect magnitude estimates and finite fault slip modelling because of its critical period ranges on their estimations, may be common in the source areas of subduction earthquakes where thick, low-velocity sediment layers are present.

  18. HIV among injection drug users in large US metropolitan areas, 1998.

    PubMed

    Friedman, Samuel R; Lieb, Spencer; Tempalski, Barbara; Cooper, Hannah; Keem, Marie; Friedman, Risa; Flom, Peter L

    2005-09-01

    This article estimates HIV prevalence rates among injection drug users (IDUs) in 95 large US metropolitan areas to facilitate social and policy analyses of HIV epidemics. HIV prevalence rates among IDUs in these metropolitan areas were calculated by taking the mean of two estimates: (1) estimates based on regression adjustments to Centers for Disease Control and Prevention (CDC) Voluntary HIV Counseling and Testing data and (2) estimates based on the ratio of the number of injectors living with HIV to the number of injectors living in the metropolitan area. The validity of the resulting estimates was assessed. HIV prevalence rates varied from 2 to 28% (median 5.9%; interquartile range 4.0-10.2%). These HIV prevalence rates correlated with similar estimates calculated for 1992 and with two theoretically related phenomena: laws against over-the-counter purchase of syringes and income inequality. Despite limitations in the accuracy of these estimates, they can be used for structural analyses of the correlates, predictors and consequences of HIV prevalence rates among drug injectors in metropolitan areas and for assessing and targeting the service needs for drug injectors.

  19. Long-period ocean-bottom motions in the source areas of large subduction earthquakes

    NASA Astrophysics Data System (ADS)

    Nakamura, Takeshi; Takenaka, Hiroshi; Okamoto, Taro; Ohori, Michihiro; Tsuboi, Seiji

    2015-11-01

    Long-period ground motions in plain and basin areas on land can cause large-scale, severe damage to structures and buildings and have been widely investigated for disaster prevention and mitigation. However, such motions in ocean-bottom areas are poorly studied because of their relative insignificance in uninhabited areas and the lack of ocean-bottom strong-motion data. Here, we report on evidence for the development of long-period (10-20 s) motions using deep ocean-bottom data. The waveforms and spectrograms demonstrate prolonged and amplified motions that are inconsistent with attenuation patterns of ground motions on land. Simulated waveforms reproducing observed ocean-bottom data demonstrate substantial contributions of thick low-velocity sediment layers to development of these motions. This development, which could affect magnitude estimates and finite fault slip modelling because of its critical period ranges on their estimations, may be common in the source areas of subduction earthquakes where thick, low-velocity sediment layers are present.

  20. Indirect searches for dark matter with the Fermi large area telescope

    DOE PAGES

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  1. Large-Area, Plasma-Assisted, Halogen-Based Diamond Deposition

    DTIC Science & Technology

    1992-03-04

    DTIC AD-A247 423 TIC RESEARCH TRIANGLE INSTITUTE RTI/5123/91-92 Quarterly March 1992 LARGE-AREA, PLASMA-ASSISTED, HALOGEN-BASED DIAMOND DEPOSITION...Quarterly Report - First and Second Quarters R.A. Rudder R.J. Markunas M.J. Mantini G.C. Hudson Office of Naval Research Program No. N00014-91-C-0177...fir , : u ____ 92-06469 POST OFFICE BOX 12194 RESEARCH TRIANGLE PARK NORTH CAROLINA 27709 2194 REPORT DOCUMENT PAGE Form Approved )OMB No 0704

  2. Design and analysis of large-effective-area heterogeneous trench-assisted multi-core fiber.

    PubMed

    Tu, Jiajing; Saitoh, Kunimasa; Koshiba, Masanori; Takenaga, Katsuhiro; Matsuo, Shoichiro

    2012-07-02

    Based on the overlap integral of electromagnetic fields in neighboring cores, a calculating method is proposed for obtaining the coupling coefficient between two adjacent trench-assisted non-identical cores. And a kind of heterogeneous trench-assisted multi-core fiber (Hetero-TA-MCF) with 12 cores is proposed to achieve large effective area (A(eff)) and high density of cores. As bending radius becomes larger than 50 mm, the crosstalk value at 1550-nm wavelength of the Hetero-TA-MCF is about -42 dB after 100-km propagation and the A(eff) of this Hetero-TA-MCF can reach 100 µm(2).

  3. Design and Characteristics of the Anticoincidence Detector for the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Moiseev, A. A.; Hartman, R. C.; Johnson, T. E.; Ormes, J. F.; Thompson, D. J.

    2005-01-01

    The Anti-Coincidence Detector (ACD) is the outermost detector layer in the GLAST Large Area Telescope (LAT), surrounding the top and sides of the tracker. The purpose of the ACD is to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly charged relativistic particles, but must also have low sensitivity to backsplash particles. These are products of high- energy interactions in the LAT calorimeter. They can cause a veto signal in the ACD, resulting in loss of good gamma-ray events.

  4. Status of GLAST, the Gamma-ray Large-area Space Telescope

    SciTech Connect

    Rochester, L.; /SLAC

    2005-12-14

    GLAST is a satellite-based observatory consisting of the Large-Area Telescope (LAT), a modular 4 x 4-tower pair-conversion telescope with a field-of-view greater than 2 steradians, capable of measuring gamma-ray energies in the range 20 MeV to 300 GeV, and the GLAST Burst Monitor (GBM), a set of NaI and BGO detectors covering 8 steradians and sensitive to photons with energies between 10 keV and 25 MeV, allowing for correlative observations of transient events. The observatory is currently being constructed and is scheduled to be launched in August 2007.

  5. Development of a large-area silicon α-particle detector.

    PubMed

    Tran, Linh T; Prokopovich, Dale A; Lerch, Michael L F; Petasecca, Marco; Siegele, Rainer; Reinhard, Mark I; Perevertaylo, Vladimir; Rosenfeld, Anatoly B

    2014-09-01

    Circular ion-implanted silicon detector of α-particles with a large, 5-cm(2), sensitive area has been developed. An advantage of the detector is that the detector surface is easily cleanable with chemicals. The hardened surface of the detector shows no signs of deterioration of the spectroscopic and electrical characteristics upon repeated cleaning. The energy resolution along the diameters of the detector was (1.0±0.1)% for the 5.486-MeV α-particles. Detailed tests of the charge collection efficiency and uniformity of the detector entrance window were also performed with a 5.5-MeV He(2+) microbeam.

  6. Indirect searches for dark matter with the Fermi large area telescope

    SciTech Connect

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  7. Torque studies of large-area Co arrays fabricated by etched nanosphere lithography

    SciTech Connect

    Weekes, S. M.; Ogrin, F.Y.

    2005-05-15

    Large-area arrays of size-tunable Co nanomagnets have been fabricated using a methodology based on nanosphere lithography. The technique employs a monolayer of latex spheres as an inverse mask for the formation of Co elements by electrodeposition. By tuning the size of the spheres with reactive ion etching, magnetic elements of 310 and 240 nm diameter have been obtained. Analysis of the arrays using high-field torque magnetometry and three-dimensional micromagnetic modeling clearly demonstrates a change in anisotropy as the diameter of the elements is reduced. More detailed investigation of the field dependence indicates the presence of magnetic vortices at low fields.

  8. Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

    PubMed

    Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

    2011-06-28

    We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

  9. The Large Area Crop Inventory Experiment /LACIE/ - A summary of three years' experience

    NASA Technical Reports Server (NTRS)

    Erb, R. B.; Moore, B. H.

    1979-01-01

    Aims, history and schedule of the Large Area Crop Inventory Experiment (LACIE) conducted by NASA, USDA and NOAA from 1974-1977 are described. The LACIE experiment designed to research, develop, apply and evaluate a technology to monitor wheat production in important regions throughout the world (U.S., Canada, USSR, Brasil) utilized quantitative multispectral data collected by Landsat in concert with current weather data and historical information. The experiment successfully exploited computer data and mathematical models to extract timely corp information. A follow-on activities for the early 1980's is planned focusing especially on the early warning of changes affecting production and quality of renewable resources and commodity production forecast.

  10. Design study of large area 8 cm x 8 cm wrapthrough cells for space station

    NASA Technical Reports Server (NTRS)

    Garlick, George F. J.; Lillington, David R.

    1987-01-01

    The design of large area silicon solar cells for the projected NASA space station is discussed. It is based on the NASA specification for the cells which calls for an 8 cm by 8 cm cell of wrapthrough type with gridded back contacts. The beginning of life (BOL) power must be 1.039 watts per cell or larger and maximum end of life (EOL) after 10 years in the prescribed orbit under an equivalent 1MeV electron radiation damage fluence of 5 times 10 to the 13th power e/square cm. On orbit efficiency is to be optimized by a low thermal absorptance goal (thermal alpha) of .63.

  11. Long life electrodes for large-area x-ray generators

    NASA Technical Reports Server (NTRS)

    Rothe, Dietmar E. (Inventor)

    1991-01-01

    This invention is directed to rugged, reliable, and long-life electrodes for use in large-area, high-current-density electron gun and x-ray generators which are employed as contamination-free preionizers for high-energy pulsed gas lasers. The electron source at the cathode is a corona plasma formed at the interface between a conductor, or semiconductor, and a high-permittivity dielectric. Detailed descriptions are provided of a reliable cold plasma cathode, as well as an efficient liquid-cooled electron beam target (anode) and x-ray generator which concentrates the x-ray flux in the direction of an x-ray window.

  12. Approaching total absorption at near infrared in a large area monolayer graphene by critical coupling

    SciTech Connect

    Liu, Yonghao; Chadha, Arvinder; Zhao, Deyin; Shuai, Yichen; Menon, Laxmy; Yang, Hongjun; Zhou, Weidong; Piper, Jessica R.; Fan, Shanhui; Jia, Yichen; Xia, Fengnian; Ma, Zhenqiang

    2014-11-03

    We demonstrate experimentally close to total absorption in monolayer graphene based on critical coupling with guided resonances in transfer printed photonic crystal Fano resonance filters at near infrared. Measured peak absorptions of 35% and 85% were obtained from cavity coupled monolayer graphene for the structures without and with back reflectors, respectively. These measured values agree very well with the theoretical values predicted with the coupled mode theory based critical coupling design. Such strong light-matter interactions can lead to extremely compact and high performance photonic devices based on large area monolayer graphene and other two–dimensional materials.

  13. Research on the mechanism of multiple inductively coupled plasma source for large area processing

    NASA Astrophysics Data System (ADS)

    Lee, Jangjae; Kim, Sijun; Kim, Daewoong; Kim, Kwangki; Lee, Youngseok; You, Shinjae

    2016-09-01

    In the plasma processing, inductively coupled plasma having the high-density is often used for high productivity. In large area plasma processing, the plasma can be generated by using the multi-pole connected in parallel. However, in case of this, it is difficult for power to be transferred to plasma uniformly. To solve the problem, we studied the mechanism of inductively coupled plasma connected in parallel. By using the transformer model, the multiple ICP source is treated. We also studied about the change of the plasma parameters over the time through the power balance equation and particle balance equation. Corresponding author.

  14. Experimental set-up for three PHOEBUS type large-area heliostats at the PSA

    SciTech Connect

    Haeger, M.; Schiel, W.; Romero, M.; Schmitz-Goeb, M.

    1995-11-01

    Three large-area heliostat prototypes are being erected at the Plataforma Solar de Almeria by Spanish and German industry. The objective is to demonstrate their technical and economical suitability for a PHOEBUS power tower plant. The two different heliostat designs including two 100 ml glass/metal faceted heliostats and one 150 m{sup 2} stressed membrane heliostat are tested at a representative distance of 485 m to the PSA`s CESA tower. The paper introduces the heliostat designs and test set-up, such as location, targets, flux measurement, data acquisition and control.

  15. Numerical modeling of large-area beta sources constructed from anodized-aluminum foils.

    PubMed

    Stanga, D

    2012-09-01

    The numerical modeling of large-area beta sources constructed from anodized-aluminum foils is described in this paper. Based on a realistic model for the activity depth distribution, theoretical lower and upper bounds for the efficiency and the transmission coefficient were calculated and used to analyze the comparison method recommended by ISO 8769 for measuring the surface emission rate. The analysis shows that this method can provide measurement results with relative standard uncertainties smaller than 3% for high energy beta emitters such as (90)Sr-(90)Y, (36)Cl and (204)Tl.

  16. Large area TES spiderweb bolometer for multi-mode cavity microwave detect

    NASA Astrophysics Data System (ADS)

    Biasotti, M.; Bagliani, D.; Ceriale, V.; Corsini, D.; De Bernardis, P.; Gatti, F.; Gualtieri, R.; Lamagna, L.; Masi, S.; Pizzigoni, G.; Schillaci, A.

    2014-07-01

    Large area spiderweb bolometers of 8 mm diameter and a mesh size of 250 μm are fabricated in order to couple with approximately the first 20 modes of a multimode EM cavity at about 140 GHz. The sensor is a Ti/Au/Ti 3 layer TES with Tc tuned in the 330-380 mK and 2 mK transition width. We describe the detector design and the fabrication process, early TES electro-thermal measurements. We also report optical coupling measurement and show the multimode coupling.

  17. A versatile fluorescence lifetime imaging system for scanning large areas with high time and spatial resolution

    NASA Astrophysics Data System (ADS)

    Bernardo, César; Belsley, Michael; de Matos Gomes, Etelvina; Gonçalves, Hugo; Isakov, Dmitry; Liebold, Falk; Pereira, Eduardo; Pires, Vladimiro; Samantilleke, Anura; Vasilevskiy, Mikhail; Schellenberg, Peter

    2014-08-01

    We present a flexible fluorescence lifetime imaging device which can be employed to scan large sample areas with a spatial resolution adjustable from many micrometers down to sub-micrometers and a temporal resolution of 20 picoseconds. Several different applications of the system will be presented including protein microarrays analysis, the scanning of historical samples, evaluation of solar cell surfaces and nanocrystalline organic crystals embedded in electrospun polymeric nanofibers. Energy transfer processes within semiconductor quantum dot superstructures as well as between dye probes and graphene layers were also investigated.

  18. Large area low cost processing for CIS photovoltaics. Final technical report

    SciTech Connect

    B. Basol; G. Norsworthy; C. Leidholm; A. Halani; R. Roe; V. Kapur

    1999-07-22

    An ink coating method was developed for CIS absorber deposition. The technique involves four processing steps: (1) preparation of a Cu-In alloy powder, (2) preparation of an ink using this powder, (3) deposition of the ink on a substrate in the form of a precursor layer, and (4) selenization to convert the Cu-In precursor into a fused CIS film. Absorbers grown by this low-cost, large-area method were used in the fabrication of 10.5% efficient solar cells.

  19. The Silicon Tracker Readout Electronics of the Gamma-ray Large Area Space Telescope

    SciTech Connect

    Baldini, Luca; Brez, Alessandro; Himel, Thomas; Hirayama, Masaharu; Johnson, R.P.; Kroeger, Wilko; Latronico, Luca; Minuti, Massimo; Nelson, David; Rando, Riccardo; Sadrozinski, H.F.-W.; Sgro, Carmelo; Spandre, Gloria; Spencer, E.N.; Sugizaki, Mutsumi; Tajima, Hiro; Cohen-Tanugi, Johann; Ziegler, Marcus; /Pisa U. /INFN, Pisa /SLAC /Maryland U. /UC, Santa Cruz /Padua U. /INFN, Padua

    2006-02-27

    A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884,736 36-cm strips using only 160 W of power, and it achieves close to 100% detection efficiency with noise occupancy sufficiently low to allow it to self trigger. The design of the readout system is described, and results are presented from ground-based testing of the completed detector system.

  20. Microfabrication of large-area circular high-stress silicon nitride membranes for optomechanical applications

    NASA Astrophysics Data System (ADS)

    Serra, E.; Bawaj, M.; Borrielli, A.; Di Giuseppe, G.; Forte, S.; Kralj, N.; Malossi, N.; Marconi, L.; Marin, F.; Marino, F.; Morana, B.; Natali, R.; Pandraud, G.; Pontin, A.; Prodi, G. A.; Rossi, M.; Sarro, P. M.; Vitali, D.; Bonaldi, M.

    2016-06-01

    In view of the integration of membrane resonators with more complex MEMS structures, we developed a general fabrication procedure for circular shape SiNx membranes using Deep Reactive Ion Etching (DRIE). Large area and high-stress SiNx membranes were fabricated and used as optomechanical resonators in a Michelson interferometer, where Q values up to 1.3 × 106 were measured at cryogenic temperatures, and in a Fabry-Pérot cavity, where an optical finesse up to 50000 has been observed.

  1. Final Scientific/Technical Report Development of Large-Area Photo-Detectors

    SciTech Connect

    Frisch, Henry J.

    2013-07-15

    This proposal requested ADR funds for two years to make measurements and detector proto-types in the context of planning a program in conjunction with Argonne National Laboratory to develop very large-area planar photodetectors. The proposed detectors have integrated transmission-line readout and sampling electronics able to achieve timing and position resolutions in the range of 1-50 psec and 1-10 mm, respectively. The capability for very precise time measurements is inherent in the design, and provides a third coordinate, orthogonal to the two in the plane, for the point of origin of photons or charged particles, allowing tomographic reconstruction in 3-dimensions inside a volume.

  2. Channel to energy calibration results for the BATSE large area detectors

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Briggs, Michael S.; Harmon, B. A.; Wilson, C. A.; Fishman, Gerald J.; Wilson, Robert B.; Meegan, Charles A.

    1994-01-01

    Continuum 16 channel spectra obtained from in flight data are used to identify and correct for nonlinearities in the channel-to-energy conversion algorithm for the BATSE large area detectors. The Crab Nebula spectra obtained by the BATSE earth occultation technique are used to characterize any nonlinearities inherent in the low energy channel bin widths on a detector by detector basis. The bin widths are optimized to remove distortions from observed gamma ray spectra. The recalibrated bin edges are used in an analysis of Crab Pulsar data to verify the improvements in the calibration.

  3. Strict dual-mode large-mode-area fiber with multicore structure

    NASA Astrophysics Data System (ADS)

    Jin, Wenxing; Ren, Guobin; Jian, Wei; Jiang, Youchao; Wu, Yue; Yang, Yuguang; Shen, Ya; Jian, Shuisheng

    2016-05-01

    In this paper, we proposed a new kind of quasi-37-cores fiber structure consisting of 15 conventional cores and 22 air-hole cores. Strict dual-mode condition is systematically analyzed about three structure parameters, core-to-core pitch, relative core diameter, and difference of refractive index between core and cladding. Large effective area about 1910.98 μm2 with low bending loss less than 10-3 dB / m is achieved while keeping strict dual-mode. This structured fiber has a great potential in high power fiber lasers and amplifiers.

  4. Electromagnetic Delineation and Confirmation of Areas of Groundwater-Surface Water Interaction in a Large River

    NASA Astrophysics Data System (ADS)

    Nadeau, J.; Dawe, M. R.; Butler, K. E.; Macquarrie, K. T.

    2004-05-01

    Riverbank filtration systems are typically located in heterogeneous alluvial river valley deposits. Delineation of riverbed areas where there is downward river water infiltration is important for determining the fluxes, quality, and travel time of water supplied to production wells. Efficient methods of delineation are especially required in large rivers that may also have relatively large water depths. A portion of the City of Fredericton well field recharge zone lies beneath the adjacent Saint John River, where a discontinuity in the clay/silt aquitard may allow hydraulic connection between the esker-like aquifer and the river. In this project we have investigated the potential for using electromagnetic methods to delineate zones of low electrical conductivity. Such zones, in a fresh water environment, suggest the absence of clay/silt materials. During the summers of 2001 and 2002, a total of 120 km of electromagnetic data were acquired using the Geonics EM31 and EM34 ground conductivity meters. The survey was carried out using an outboard-motor-powered canoe and raft with onboard DGPS system. Both electromagnetic instruments were operated in the vertical dipole mode, thereby providing maximum depths of exploration of approximately 30 meters. The water depths in the survey area fall in the range where the EM31 and EM34 results are very sensitive to the conductivity structure. We applied a novel bathymetry correction approach to compensate for water depth effects. Contouring of the apparent conductivity data revealed a conductivity low with an approximate area of 6 hectares. The absence of the clay/silt aquitard was confirmed by high resolution seismic profiling and drilling and sampling of riverbed sediments. Further confirmation of river water infiltration has been provided by hydraulic data from mini-piezometers and temperature time series collected beneath the riverbed. Apparent conductivity mapping proved to be a sensitive and efficient method for delineating

  5. Detailed study of bending effects in large mode area segmented cladding fibers.

    PubMed

    Ma, Shaoshuo; Ning, Tigang; Li, Jing; Pei, Li; Zhang, Chuanbiao; Wen, Xiaodong

    2016-12-10

    This paper studies the bending effects on segmented cladding fibers (SCFs) in detail. Rod-type SCFs have offered large effective mode areas (EMAs) very successfully. The low-index segments in the design also enable the optical fibers to be bend-resistant. In this paper, the bending performance of the SCFs has been investigated by using the finite element method. The results indicate that SCFs can provide low-loss effective single-mode operation in a wide bandwidth under a bent configuration, due to the leakage losses of the higher-order modes (HOMs). A large ratio between the HOMs and the fundamental mode losses can be ensured, over a wide range of duty cycle, refractive index difference, and bending radius. Therefore, the required fabrication accuracy decreases. The mode loss ratio and EMA are independent of the bending orientation. Operating at 1550 nm and 10 cm bend radius, large EMA (754  μm2) is achievable with a large loss ratio (>30). The trade-offs between loss, EMA, and bending are studied. The structure has potential for compact high power fiber lasers, amplifiers, and beam delivery applications.

  6. Observation and analysis of high-speed human motion with frequent occlusion in a large area

    NASA Astrophysics Data System (ADS)

    Wang, Yuru; Liu, Jiafeng; Liu, Guojun; Tang, Xianglong; Liu, Peng

    2009-12-01

    The use of computer vision technology in collecting and analyzing statistics during sports matches or training sessions is expected to provide valuable information for tactics improvement. However, the measurements published in the literature so far are either unreliably documented to be used in training planning due to their limitations or unsuitable for studying high-speed motion in large area with frequent occlusions. A sports annotation system is introduced in this paper for tracking high-speed non-rigid human motion over a large playing area with the aid of motion camera, taking short track speed skating competitions as an example. The proposed system is composed of two sub-systems: precise camera motion compensation and accurate motion acquisition. In the video registration step, a distinctive invariant point feature detector (probability density grads detector) and a global parallax based matching points filter are used, to provide reliable and robust matching across a large range of affine distortion and illumination change. In the motion acquisition step, a two regions' relationship constrained joint color model and Markov chain Monte Carlo based joint particle filter are emphasized, by dividing the human body into two relative key regions. Several field tests are performed to assess measurement errors, including comparison to popular algorithms. With the help of the system presented, the system obtains position data on a 30 m × 60 m large rink with root-mean-square error better than 0.3975 m, velocity and acceleration data with absolute error better than 1.2579 m s-1 and 0.1494 m s-2, respectively.

  7. Footprints of triggering in large area surveys of the nearby ISM and YSOs

    NASA Astrophysics Data System (ADS)

    Tóth, L. Viktor; Kiss, Zoltán T.

    Introduction: Our goal is to evaluate the role of trigger effects on the star formation and early stellar evolution by presenting statistically large sample of cloud and low-mass YSO data. Methods: We conducted large area surveys (ranging from 400square-degree to10800square-degree) in optical, NIR and FIR. The distribution of the ISM and low-mass YSOs were surveyed. Results: (1) We pointed out that according to the IRAS FIR data, the structure of the cold ISM is Swiss-cheese-like and compiled an all-sky catalogue of FIR loops (Kiss, Moór Tóth, 2004, A&A 418, 131, and Könyves et al. 2006 A&A submitted). (2) We identified more than 200 interstellar clouds in the Cepheus region, described their morphology and derived their FIR properties (Kiss, Tóth, Krause et al. 2006 A&A in press). (3) We analysed the distribution of classical TTauri candidate objects on very large areas finding galactic large scale distribution, clustering and local inhomogenities by a statistical investigation. Discussion: (1) A relative excess was found statistically in the number of clouds in the direction of the FIR loop shells indicating a possible excess formation. This is a complementary data set to eg. HI all-sky surveys. (2) We demonstrated the differences between the cloud and star formation activity in unperturbed and loop shell regions of the Upper Cepheus region showing possible trigger effects (Kiss, Tóth, Krause et al. 2006 A&A in press). (3) The obtained distribution of low-mass YSOs may be used in comparison with theoretical models and numerical simulations, as well as predictions for further surveys.

  8. Applying Bronfenbrenner's Ecological Model to Identify the Negative Influences Facing Children with Physical Disabilities in Rural Areas in Kwa-Zulu Natal

    ERIC Educational Resources Information Center

    Ben-David, Brenda; Nel, Norma

    2013-01-01

    Children with visible physical disabilities (CWPDs) living in rural areas of South Africa are a matter of particular concern. While all children living in rural areas face negative influences such as poverty and the high incidence of HIV/AIDS, this situation is exacerbated for CWPDs who are more vulnerable to these influences (Human Sciences…

  9. The mechanism of the area negative thermal expansion in KBe{sub 2}BO{sub 3}F{sub 2} family crystals: A first-principles study

    SciTech Connect

    Jiang, Xingxing; Molokeev, Maxim S.; Li, Wei; Wu, Shaofan; Lin, Zheshuai Wu, Yicheng; Chen, Chuangtian

    2016-02-07

    A very recent study demonstrated that the KBe{sub 2}BO{sub 3}F{sub 2} (KBBF) family of crystals, including KBBF, RbBe{sub 2}BO{sub 3}F{sub 2}, and CsBe{sub 2}BO{sub 3}F{sub 2}, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO{sub 3}F] tetrahedra in the two-dimensional [Be{sub 2}BO{sub 3}F{sub 2}]{sub ∞} framework with respect to temperature, while the [BO{sub 3}] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be{sub 2}BO{sub 3}F{sub 2}]{sub ∞} layer.

  10. Interference lithographically defined and catalytically etched, large-area silicon nanocones from nanowires.

    PubMed

    Dawood, M K; Liew, T H; Lianto, P; Hong, M H; Tripathy, S; Thong, J T L; Choi, W K

    2010-05-21

    We report a simple and cost effective method for the synthesis of large-area, precisely located silicon nanocones from nanowires. The nanowires were obtained from our interference lithography and catalytic etching (IL-CE) method. We found that porous silicon was formed near the Au catalyst during the fabrication of the nanowires. The porous silicon exhibited enhanced oxidation ability when exposed to atmospheric conditions or in wet oxidation ambient. Very well located nanocones with uniform sharpness resulted when these oxidized nanowires were etched in 10% HF. Nanocones of different heights were obtained by varying the doping concentration of the silicon wafers. We believe this is a novel method of producing large-area, low cost, well defined nanocones from nanowires both in terms of the control of location and shape of the nanocones. A wide range of potential applications of the nanocone array can be found as a master copy for nanoimprinted polymer substrates for possible biomedical research; as a candidate for making sharp probes for scanning probe nanolithography; or as a building block for field emitting tips or photodetectors in electronic/optoelectronic applications.

  11. Model for large-area monolayer coverage of polystyrene nanospheres by spin coating

    PubMed Central

    Chandramohan, Abhishek; Sibirev, Nikolai V.; Dubrovskii, Vladimir G.; Petty, Michael C.; Gallant, Andrew J.; Zeze, Dagou A.

    2017-01-01

    Nanosphere lithography, an inexpensive and high throughput technique capable of producing nanostructure (below 100 nm feature size) arrays, relies on the formation of a monolayer of self-assembled nanospheres, followed by custom-etching to produce nanometre size features on large-area substrates. A theoretical model underpinning the self-ordering process by centrifugation is proposed to describe the interplay between the spin speed and solution concentration. The model describes the deposition of a dense and uniform monolayer by the implicit contribution of gravity, centrifugal force and surface tension, which can be accounted for using only the spin speed and the solid/liquid volume ratio. We demonstrate that the spin recipe for the monolayer formation can be represented as a pathway on a 2D phase plane. The model accounts for the ratio of polystyrene nanospheres (300 nm), water, methanol and surfactant in the solution, crucial for large area uniform and periodic monolayer deposition. The monolayer is exploited to create arrays of nanoscale features using ‘short’ or ‘extended’ reactive ion etching to produce 30–60 nm (diameter) nanodots or 100–200 nm (diameter) nanoholes over the entire substrate, respectively. The nanostructures were subsequently utilized to create master stamps for nanoimprint lithography. PMID:28102358

  12. On the potential and limits of large area seeding for photovoltaic silicon

    NASA Astrophysics Data System (ADS)

    Stoddard, Nathan; Gründig-Wendrock, Bianca; Krause, Andreas; Oriwol, Daniel; Bertoni, Mariana; Naerland, Tine Uberg; Witting, Ian; Sylla, Lamine

    2016-10-01

    Single crystal production of silicon for solar cell substrates has relied on the Dash neck technique developed more than 50 years ago. The technique is simple and repeatable and enables truly dislocation free crystal growth. It does have drawbacks, however, including limits on throughput and some structural difficulties. It has long been assumed that dislocation-free growth is not possible by any other method. In the 'quasi-mono' crystal growth technique, one of the key elements is the use of large area single crystal seeds. By melting the seeds at near-equilibrium conditions, it is feasible to avoid the production of dislocations during melting. We will review the dislocation relevant details of the large area seeding process and present best case results for dislocation density, including measured minority carrier lifetimes in excess of 1 ms on p-type material. We will focus on dislocation density exclusive of seed boundaries, but we will also present a potential best-case limit for the technique.

  13. The role of printing techniques for large-area dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mariani, Paolo; Vesce, Luigi; Di Carlo, Aldo

    2015-10-01

    The versatility of printing technologies and their intrinsic ability to outperform other techniques in large-area deposition gives scope to revolutionize the photovoltaic (PV) manufacturing field. Printing methods are commonly used in conventional silicon-based PVs to cover part of the production process. Screen printing techniques, for example, are applied to deposit electrical contacts on the silicon wafer. However, it is with the advent of third generation PVs that printing/coating techniques have been extensively used in almost all of the manufacturing processes. Among all the third generation PVs, dye sensitized solar cell (DSSC) technology has been developed up to commercialization levels. DSSCs and modules can be fabricated by adopting all of the main printing techniques on both rigid and flexible substrates. This allows an easy tuning of cell/module characteristics to the desired application. Transparency, colour, shape, layout and other DSSC’s features can be easily varied by changing the printing parameters and paste/ink formulations used in the printing process. This review focuses on large-area printing/coating technologies for the fabrication of DSSCs devices. The most used and promising techniques are presented underlining the process parameters and applications.

  14. Large area single and bilayer graphene with controlled orientation for each layer

    NASA Astrophysics Data System (ADS)

    Brown, Lola; Lochocki, Edward; Gutiérrez, Christopher; Pasupathy, Abhay; Shen, Kyle; Park, Jiwoong; Cornell Collaboration; Cornell-Columbia Collaboration

    2014-03-01

    The creation and exploration of artificial graphene structures has recently become the focus of great interest. In particular, controlling the interlayer twist angles in multilayer graphene stacks allows modulation of the overall band structure. However, producing such a structure remains difficult due to the random distribution of twist angles in as-grown samples. Here we report a novel way for creating large area graphene stacks with a pre-determined twist angle. We first grow single layer graphene whose orientation is aligned over a few cm length scale on copper foil. The overall angle alignment of the graphene is confirmed using low energy electron microscopy (LEED) and transmission electron microscopy techniques. Since the graphene is well aligned over a few centimeters, we can create large area graphene stacks with known twist angle by transferring these graphene layers while controlling the orientation of each layer during transfer. We confirm that the layers are coupled by probing the resulting band structure using angle resolved photoemission spectroscopy (ARPES), and examining their interlayer optical resonance features using spatially resolved hyperspectral (DUV-Vis-NIR wavelengths). This new method is scalable, and controllable and thus paves the way to explore and exploit the novel properties of two-dimensional crystals in artificial stacks with controlled interlayer structures. Second affiliation: Kavli Institute at Cornell for Nanoscale Science.

  15. Multifunctionality and Control of the Crumpling and Unfolding of Large-Area Graphene

    PubMed Central

    Zang, Jianfeng; Ryu, Seunghwa; Pugno, Nicola; Wang, Qiming; Tu, Qing; Buehler, Markus J.; Zhao, Xuanhe

    2012-01-01

    Crumpled graphene films are broadly used, for instance in electronics1, energy storage2, 3, composites4, 5, and biomedicine6. Although it is known that the degree of crumpling affects graphene's properties and the performance of graphene-based devices and materials3, 5, 7, the controlled folding and unfolding of crumpled graphene films has not been demonstrated. Here we report an approach to reversibly control the crumpling and unfolding of large-area graphene sheets. We show with experiments, atomistic simulations and theory that, by harnessing the mechanical instabilities of graphene adhered on a biaxially pre-stretched polymer substrate and by controlling the relaxation of the pre-strains in a particular order, graphene films can be crumpled into tailored self-organized hierarchical structures that mimic superhydrophobic leaves. The approach enables us to fabricate large-area conductive coatings and electrodes showing superhydrophobicity, high transparency, and tunable wettability and transmittance. We also demonstrate that crumpled graphene-polymer laminates can be used as artificial-muscle actuators. PMID:23334002

  16. Large-area arrays of gold nanotructures from azopolymer templates (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Moerland, Robert J.; Koskela, Jenni E.; Kaivola, Matti; Ras, Robin H. A.; Priimagi, Arri

    2016-09-01

    Subwavelength-sized, periodically arranged holes in an opaque metal film have gained much attention since 1998, when Ebbesen et al. first reported the phenomenon of enhanced transmission of light through such a hole-array structure. Certain wavelengths show distinctly higher transmission than what would be expected based simply on the number of holes and the transmission of a single subwavelength hole, a phenomenon commonly attributed to different plasmonic modes in nanohole arrays. Traditionally, nanoscale holes and slits in metal films have been fabricated via electron-beam lithography or focused ion beam milling. Typically, finite hole arrays up to 50 μm in size with high control over hole size, shape, periodicity and resolution can be created with these methods. However, EBL and FIB become very costly and time-consuming to make larger-sized hole arrays and are not suitable for low-cost mass production. Herein, we exploit surface patterns on azopolymer films for making highly ordered and uniform arrays of nanoholes and nanoislands in thin gold films. The nanostructures can be created by employing azopolymer surface patterns as a template for metal deposition, after which the metal surface is subjected to large-area ion milling. Azopolymer-based surface patterning provides an easy way to vary the size and periodicity of the structures, which are manufactured homogeneously over large areas. The largest possible size of the structures depends merely on the size of the optical inscription beam and the used ion milling apparatus.

  17. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    NASA Astrophysics Data System (ADS)

    Diao, Ying; Tee, Benjamin C.-K.; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Hector A.; Stoltenberg, Randall M.; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2013-07-01

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach—termed fluid-enhanced crystal engineering (FLUENCE)—that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s-1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics.

  18. Reconstruction of Large Defects in the Perineal Area Using Multiple Perforator Flaps

    PubMed Central

    Sung, Ki Wook; Lee, Won Jai; Yun, In Sik

    2016-01-01

    Background Perineal defects are commonly encountered during the treatment of conditions such as malignancy, infectious disease, and trauma. Covering large defects in the perineal area is challenging due to its complicated anatomy and the need for functional preservation. Methods Fourteen patients who underwent reconstructive surgery with multiple perforator flaps for defects >100 cm2 in the perineal area were included in this retrospective cohort study. Characteristics of the perforator flap operation and postoperative outcomes were reviewed. Results Reconstruction was performed using 2 perforator flaps for 13 patients and 3 perforator flaps for 1 patient. Internal pudendal artery perforator flaps were mainly used for covering the defects. The average defect size was 176.3±61.8 cm2 and the average size of each flap was 95.7±31.9 cm2. Six patients had minor complications, such as wound dehiscence and partial necrosis of the flap margin, which were corrected with simple revision procedures. Conclusions Multiple perforator flaps can be used to achieve successful reconstructions of large perineal defects that are difficult to reconstruct with other coverage methods. PMID:27689052

  19. Large area 3-D optical coherence tomography imaging of lumpectomy specimens for radiation treatment planning

    NASA Astrophysics Data System (ADS)

    Wang, Cuihuan; Kim, Leonard; Barnard, Nicola; Khan, Atif; Pierce, Mark C.

    2016-02-01

    Our long term goal is to develop a high-resolution imaging method for comprehensive assessment of tissue removed during lumpectomy procedures. By identifying regions of high-grade disease within the excised specimen, we aim to develop patient-specific post-operative radiation treatment regimens. We have assembled a benchtop spectral-domain optical coherence tomography (SD-OCT) system with 1320 nm center wavelength. Automated beam scanning enables "sub-volumes" spanning 5 mm x 5 mm x 2 mm (500 A-lines x 500 B-scans x 2 mm in depth) to be collected in under 15 seconds. A motorized sample positioning stage enables multiple sub-volumes to be acquired across an entire tissue specimen. Sub-volumes are rendered from individual B-scans in 3D Slicer software and en face (XY) images are extracted at specific depths. These images are then tiled together using MosaicJ software to produce a large area en face view (up to 40 mm x 25 mm). After OCT imaging, specimens were sectioned and stained with HE, allowing comparison between OCT image features and disease markers on histopathology. This manuscript describes the technical aspects of image acquisition and reconstruction, and reports initial qualitative comparison between large area en face OCT images and HE stained tissue sections. Future goals include developing image reconstruction algorithms for mapping an entire sample, and registering OCT image volumes with clinical CT and MRI images for post-operative treatment planning.

  20. A technique for large-area position-controlled growth of GaAs nanowire arrays

    NASA Astrophysics Data System (ADS)

    Kauppinen, Christoffer; Haggren, Tuomas; Kravchenko, Aleksandr; Jiang, Hua; Huhtio, Teppo; Kauppinen, Esko; Dhaka, Veer; Suihkonen, Sami; Kaivola, Matti; Lipsanen, Harri; Sopanen, Markku

    2016-04-01

    We demonstrate a technique for fabricating position-controlled, large-area arrays of vertical semiconductor nanowires (NWs) with adjustable periods and NW diameters. In our approach, a Au-covered GaAs substrate is first coated with a thin film of photoresponsive azopolymer, which is exposed twice to a laser interference pattern forming a 2D surface relief grating. After dry etching, an array of polymer islands is formed, which is used as a mask to fabricate a matrix of gold particles. The Au particles are then used as seeds in vapour-liquid-solid growth to create arrays of vertical GaAs NWs using metalorganic vapour phase epitaxy. The presented technique enables producing NWs of uniform size distribution with high throughput and potentially on large wafer sizes without relying on expensive lithography techniques. The feasibility of the technique is demonstrated by arrays of vertical NWs with periods of 255-1000 nm and diameters of 50-80 nm on a 2 × 2 cm area. The grown NWs exhibit high long range order and good crystalline quality. Although only GaAs NWs were grown in this study, in principle, the presented technique is suitable for any material available for Au seeded NW growth.