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Sample records for photonic wire geometry

  1. Antenna coupled photonic wire lasers

    DOE PAGES

    Kao, Tsung-Kao; Cai, Xiaowei; Lee, Alan W. M.; ...

    2015-06-22

    Slope efficiency (SE) is an important performance metric for lasers. In conventional semiconductor lasers, SE can be optimized by careful designs of the facet (or the modulation for DFB lasers) dimension and surface. However, photonic wire lasers intrinsically suffer low SE due to their deep sub-wavelength emitting facets. Inspired by microwave engineering techniques, we show a novel method to extract power from wire lasers using monolithically integrated antennas. These integrated antennas significantly increase the effective radiation area, and consequently enhance the power extraction efficiency. When applied to wire lasers at THz frequency, we achieved the highest single-side slope efficiency (~450more » mW/A) in pulsed mode for DFB lasers at 4 THz and a ~4x increase in output power at 3 THz compared with a similar structure without antennas. This work demonstrates the versatility of incorporating microwave engineering techniques into laser designs, enabling significant performance enhancements.« less

  2. Antenna coupled photonic wire lasers

    SciTech Connect

    Kao, Tsung-Kao; Cai, Xiaowei; Lee, Alan W. M.; Reno, John L.; Hu, Qing

    2015-06-22

    Slope efficiency (SE) is an important performance metric for lasers. In conventional semiconductor lasers, SE can be optimized by careful designs of the facet (or the modulation for DFB lasers) dimension and surface. However, photonic wire lasers intrinsically suffer low SE due to their deep sub-wavelength emitting facets. Inspired by microwave engineering techniques, we show a novel method to extract power from wire lasers using monolithically integrated antennas. These integrated antennas significantly increase the effective radiation area, and consequently enhance the power extraction efficiency. When applied to wire lasers at THz frequency, we achieved the highest single-side slope efficiency (~450 mW/A) in pulsed mode for DFB lasers at 4 THz and a ~4x increase in output power at 3 THz compared with a similar structure without antennas. This work demonstrates the versatility of incorporating microwave engineering techniques into laser designs, enabling significant performance enhancements.

  3. Antenna coupled photonic wire lasers

    DOE PAGES

    Kao, Tsung-Kao; Cai, Xiaowei; Lee, Alan W. M.; ...

    2015-06-22

    Slope efficiency (SE) is an important performance metric for lasers. In conventional semiconductor lasers, SE can be optimized by careful designs of the facet (or the modulation for DFB lasers) dimension and surface. However, photonic wire lasers intrinsically suffer low SE due to their deep sub-wavelength emitting facets. Inspired by microwave engineering techniques, we show a novel method to extract power from wire lasers using monolithically integrated antennas. These integrated antennas significantly increase the effective radiation area, and consequently enhance the power extraction efficiency. When applied to wire lasers at THz frequency, we achieved the highest single-side slope efficiency (~450more » mW/A) in pulsed mode for DFB lasers at 4 THz and a ~4x increase in output power at 3 THz compared with a similar structure without antennas. This work demonstrates the versatility of incorporating microwave engineering techniques into laser designs, enabling significant performance enhancements.« less

  4. Silicon Photonic Wire Waveguides: Fundamentals and Applications

    NASA Astrophysics Data System (ADS)

    Yamada, Koji

    This chapter reviews the fundamental characteristics and basic applications of the silicon photonic wire waveguide. Thanks to its ultra-small geometrical structures and compatibility with the silicon electronics, the silicon photonic wire waveguide provides us with a highly integrated platform for electronic-photonic convergence. For the practical achievement of this platform, however, we must search for ways to reduce the propagation loss and coupling loss to external fibers and overcome the polarization dependence. Progress has been made by applying state-of-the-art technologies specially tuned to the fabrication of nanometer structures, and the fundamental propagation performance has already become a practical standard. Some passive devices, such as branches and wavelength filters, and dynamic devices based on the thermo-optic effect or carrier plasma effect have been developed by using silicon photonic wire waveguides. These waveguides also offer an efficient media for nonlinear optical functions, such as wavelength conversion. Although polarization dependence remains a serious obstacle to the practical applications of these waveguides, waveguide-based polarization manipulation devices provide us with effective solutions, such as a polarization diversity system.

  5. Optical gain in single tensile-strained germanium photonic wire.

    PubMed

    de Kersauson, M; El Kurdi, M; David, S; Checoury, X; Fishman, G; Sauvage, S; Jakomin, R; Beaudoin, G; Sagnes, I; Boucaud, P

    2011-09-12

    We have investigated the optical properties of tensile-strained germanium photonic wires. The photonic wires patterned by electron beam lithography (50 μm long, 1 μm wide and 500 nm thick) are obtained by growing a n-doped germanium film on a GaAs substrate. Tensile strain is transferred in the germanium layer using a Si₃N₄ stressor. Tensile strain around 0.4% achieved by the technique corresponds to an optical recombination of tensile-strained germanium involving light hole band around 1690 nm at room temperature. We show that the waveguided emission associated with a single tensile-strained germanium wire increases superlinearly as a function of the illuminated length. A 20% decrease of the spectral broadening is observed as the pump intensity is increased. All these features are signatures of optical gain. A 80 cm⁻¹ modal optical gain is derived from the variable strip length method. This value is accounted for by the calculated gain material value using a 30 band k · p formalism. These germanium wires represent potential building blocks for integration of nanoscale optical sources on silicon.

  6. Few-photon transport in quasi-one-dimensional geometries

    NASA Astrophysics Data System (ADS)

    Ralley, Kevin

    An analysis of some aspects of photon transport through cavities and emitters embedded in a one-dimensional geometries is presented. The concept of photon blockade is defined for few-photon states interacting with a single two-level atom and the strength of achievable blockade is calculated in this setting. A brief review of some promising schemes for achieving photon blockade from the literature is also provided. The conflict between linear and nonlinear optical processes is studied for a novel version of the famous Hong-Ou-Mandel effect in a photonic waveguide with a side-coupled two-level emitter.

  7. Stiff Monatomic Gold Wires with a Spinning Zigzag Geometry

    SciTech Connect

    Sanchez-Portal, D.; Artacho, E.; Junquera, J.; Soler, J.M.; Ordejon, P.; Garcia, A.

    1999-11-01

    Using first-principles density-functional calculations, gold monatomic wires are found to exhibit a zigzag shape which remains under tension, becoming linear just before breaking. At room temperature they are found to spin, which explains the extremely long apparent interatomic distances shown by electron microscopy. The zigzag structure is stable if the tension is relieved, the wire holding its chainlike shape even as a free-standing cluster. This unexpected metallic-wire stiffness stems from the transverse quantization in the wire, as shown in a simple free electron model. {copyright} {ital 1999} {ital The American Physical Society }

  8. Stiff monatomic gold wires with a spinning zigzag geometry

    NASA Astrophysics Data System (ADS)

    Soler, José M.; Sánchez-Portal, Daniel; Artacho, Emilio; Junquera, Javier; Ordejón, García, Alberto

    2000-03-01

    We have recently studied( D. Sánchez-Portal, E. Artacho, J. Junquera, P. Ordejón, A. Garcí)a, J. Soler, Phys. Rev. Lett 83, 3884 (1999). the structure and elastical properties of gold monatomic wires by means of first principles density functional calculations. The wires are found to exhibit a zigzag shape which remains under tension, becoming linear just before breaking. At room temperature they are found to spin, what explains the extremely long apparent interatomic distances shown by electron microscopy. The zigzag structure is stable if the tension is relieved, the wire holding its chainlike shape even as a free-standing cluster. This unexpected metallic-wire stiffness stems from the transverse quantization in the wire, as shown in a simple free electron model.

  9. Application of the Wire Ablation Dynamics Model to the Design and Optimization of Wire Array Loads of Complex Geometry

    SciTech Connect

    Esaulov, A. A.; Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M.; Shrestha, I.; Osborne, G. C.

    2009-01-21

    The implosion dynamics of wire array loads of complex geometry, such as nested cylindrical and planar wire arrays, is significantly affected by the uneven current distribution between the array wires, which was considered previously in the Wire Dynamics Model (WDM) simulations. The novel Wire Ablation Dynamics Model (WADM) extends the formalism of the original WDM by including the dynamics of wire ablation. The WADM simulations demonstrate that the implosions of the arrays with higher masses are more ablation dominated. The WADM simulations of the implosions dynamics of nested wire arrays have been performed for the short pulse (100 ns) and long pulse (220 ns) regimes at COBRA generator. Another factor that affects the result of the trade between the ablation and implosion time scales is the form of the current pulse, which can be very different from the classical sine-square shape. The predictions of the array implosion times by the WADM are in very good agreement with the recent experiments at the COBRA and Zebra facilities.

  10. Solitons and spectral broadening in long silicon-on- insulator photonic wires.

    PubMed

    Ding, W; Benton, C; Gorbach, A V; Wadsworth, W J; Knight, J C; Skryabin, D V; Gnan, M; Sorrel, M; De La Rue, R M

    2008-03-03

    We report measurements and numerical modeling of spectral broadening and soliton propagation regimes in silicon-on-insulator photonic wire waveguides of 3 to 4 dispersion lengths using 100fs pump pulses. We also present accurate measurements of the group index and dispersion of the photonic wire.

  11. Nonlinear optics in silicon photonic wires: Theory and applications

    NASA Astrophysics Data System (ADS)

    Chen, Xiaogang

    Silicon photonic wires (SPW) are deeply scaled silicon waveguides with transverse dimensions much less than 1 mum. Integrated silicon photonic devices based on SPW generally have very small footprint and very strong light confinement, which lead to many advantageous physical properties: capability for dispersion engineering, high optical-field density, enhanced effective nonlinearity, and intrinsically short carrier lifetime. Third-order nonlinearities, dispersion effects up to the third-order and carrier effects are the three major contributors to the rich pulse dynamics in SPW. In this thesis, various nonlinear optical processes in SPW such as stimulated Raman Scattering (SRS), self-phase modulation (SPM), cross-phase modulation (XPM), modulation instability (MI), and third-order dispersion (TOD) induced soliton-radiation effect are studied theoretically and experimentally. After a brief introduction of silicon photonics, I first present a comprehensive theoretical model developed from Maxwell's equations and the Lorentz reciprocity theorem for describing pulse dynamics in high-index-contrast and anisotropic waveguides. Chapter 3 focuses on exploring the capability of "engineering" the optical dispersion, which enables the control of phase matching of nonlinear pulse dynamics and is important to the development of nonlinear optical functionalities of SPW. In linear regime, SPW is shown to support wavelength-division multiplexing (WDM) transmission at an ultra-high-data-rate of 300 Gb/s for intra-chip optical network. SPM is the result of optical Kerr effect, which manifests as an intensity-dependent refractive index change. In Chapter 4, SPM of optical pulses with temporal widths in both picosecond and femtosecond regimes is studied experimentally and theoretically. In the femtosecond regime, the interplay of nonlinear effects, group-velocity-dispersion (GVD) and TOD results in soliton-like pulse propagation in SPW. TOD-induced soliton radiation was demonstrated

  12. The geometry effect on energy transfer rate in a coupled-quantum-wires structure

    NASA Astrophysics Data System (ADS)

    Rafee, Vahdat

    2016-03-01

    The geometry effect on energy transfer rate in a coupled cylindrical quantum wires system is investigated. The corrected random phase approximation by the zero-temperature static Hubbard correction is employed to calculate dielectric function of the system. The geometry effect on energy transfer rate is studied for statically and dynamically screened electron-electron interaction. Both the linear and nonlinear regimes correspond respectively to weak and strong external field are considered. The calculations show that increasing wire radius increases energy transfer rate in both the static and dynamic screening approximations for electron-electron interactions. Moreover, the same trend is predicted by the calculations for both the linear and nonlinear regimes.

  13. Effect of geometry on the screened acceptor binding energy in a quantum wire

    SciTech Connect

    Shanthi, R. Vijaya Nithiananthi, P.

    2014-04-24

    The effect of various Geometries G(x, y) of the GaAs/Al{sub x}Ga{sub 1−x}As Quantum wire like G{sub 1}: (L, L) {sub 2}: (L, L/2) {sub 3}: (L/2, L/4) on the binding energy of an on-center acceptor impurity has been investigated through effective mass approximation using variational technique. The observations were made including the effect of spatial dependent dielectric screening for different concentration of Al, at T=300K. The influence of spatial dielectric screening on different geometries of the wire has been compared and hence the behavior of the acceptor impurity in GaAs/Al{sub x}Ga{sub 1−x}As Quantum wire has been discussed.

  14. Geometry effects on magnetization dynamics in circular cross-section wires

    SciTech Connect

    Sturma, M.; Toussaint, J.-C. E-mail: daria.gusakova@cea.fr; Gusakova, D. E-mail: daria.gusakova@cea.fr

    2015-06-28

    Three-dimensional magnetic memory design based on circular-cross section nanowires with modulated diameter is the emerging field of spintronics. The consequences of the mutual interaction between electron spins and local magnetic moments in such non-trivial geometries are still open to debate. This paper describes the theoretical study of domain wall dynamics within such wires subjected to spin polarized current. We used our home-made finite element software to characterize the variety of domain wall dynamical regimes observed for different constriction to wire diameter ratios d/D. Also, we studied how sizeable geometry irregularities modify the internal micromagnetic configuration and the electron spin spatial distribution in the system, the geometrical reasons underlying the additional contribution to the system's nonadiabaticity, and the specific domain wall width oscillations inherent to fully three-dimensional systems.

  15. Geometry effects on magnetization dynamics in circular cross-section wires

    NASA Astrophysics Data System (ADS)

    Sturma, M.; Toussaint, J.-C.; Gusakova, D.

    2015-06-01

    Three-dimensional magnetic memory design based on circular-cross section nanowires with modulated diameter is the emerging field of spintronics. The consequences of the mutual interaction between electron spins and local magnetic moments in such non-trivial geometries are still open to debate. This paper describes the theoretical study of domain wall dynamics within such wires subjected to spin polarized current. We used our home-made finite element software to characterize the variety of domain wall dynamical regimes observed for different constriction to wire diameter ratios d/D. Also, we studied how sizeable geometry irregularities modify the internal micromagnetic configuration and the electron spin spatial distribution in the system, the geometrical reasons underlying the additional contribution to the system's nonadiabaticity, and the specific domain wall width oscillations inherent to fully three-dimensional systems.

  16. Emergent geometries and nonlinear-wave dynamics in photon fluids

    PubMed Central

    Marino, F.; Maitland, C.; Vocke, D.; Ortolan, A.; Faccio, D.

    2016-01-01

    Nonlinear waves in defocusing media are investigated in the framework of the hydrodynamic description of light as a photon fluid. The observations are interpreted in terms of an emergent curved spacetime generated by the waves themselves, which fully determines their dynamics. The spacetime geometry emerges naturally as a result of the nonlinear interaction between the waves and the self-induced background flow. In particular, as observed in real fluids, different points of the wave profile propagate at different velocities leading to the self-steepening of the wave front and to the formation of a shock. This phenomenon can be associated to a curvature singularity of the emergent metric. Our analysis offers an alternative insight into the problem of shock formation and provides a demonstration of an analogue gravity model that goes beyond the kinematic level. PMID:27001128

  17. Wiring up pre-characterized single-photon emitters by laser lithography

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

    2016-08-01

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time.

  18. Wiring up pre-characterized single-photon emitters by laser lithography.

    PubMed

    Shi, Q; Sontheimer, B; Nikolay, N; Schell, A W; Fischer, J; Naber, A; Benson, O; Wegener, M

    2016-08-10

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time.

  19. Wiring up pre-characterized single-photon emitters by laser lithography

    PubMed Central

    Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

    2016-01-01

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time. PMID:27507165

  20. Numerical investigation on the implosion dynamics of wire-array Z-pinches in (r, {theta}) geometry

    SciTech Connect

    Huang Jun; Ding Ning; Ning Cheng; Sun Shunkai; Zhang Yang; Xiao Delong; Xue Chuang

    2012-06-15

    The implosion dynamics of wire-array Z-pinches are investigated numerically in 2D (r, {theta}) geometry by using a resistive MHD code. It is assumed that the wires have expanded to plasmas with diameter d{sub 0}, which is used as the initial condition for the consequent implosion process. In fact, the explosion process of individual wires is not included. By changing d{sub 0}, the effects of the wire expansion degree on the implosion dynamics are analyzed. When d{sub 0} is larger, the current density is more concentrated at the outer side of the wires and the fraction of current flow around the wire plasmas is nearly in proportion to d{sub 0}. As a result, the ablation rate of wires is increased and the implosion phase starts earlier. This conclusion agrees with the simulation works of other authors [Chittenden et al., Phys. Plasmas 11(3), 1118 (2004)]. When the array radius and initial wire plasma diameter are fixed, the increase of wire number leads to the azimuthal merge of wires during implosion. When the wires number exceed a critical value, which is related to d{sub 0}, wire plasmas can merge to a continuous shell with an azimuthal perturbation in density, which depends on the initial wires number.

  1. A geometry optimization framework for photonic crystal design

    NASA Astrophysics Data System (ADS)

    Hart, E. E.; Sóbester, A.; Djidjeli, K.; Molinari, M.; Thomas, K. S.; Cox, S. J.

    2012-01-01

    The performance of photonic crystal devices can depend strongly on their geometry. Alas, their fundamental physics offers relatively little by way of pointers in terms of optimum shapes, so numerical design search techniques must be used in an attempt to determine high performance layouts. We discuss strategies for solving this type of optimization problem, the main challenge of which is the conflict between the enormous size of the space of potentially useful designs and the relatively high computational cost of evaluating the performance of putative shapes. The optimization technique proposed here operates over increasing levels of fidelity, both in terms of the resolution of its non-parametric shape definition and in terms of the resolution of the numerical analysis of the performance of putative designs. This is a generic method, potentially applicable to any type of electromagnetic device shape design problem. We also consider a methodology for assessing the robustness of the optima generated through this process, investigating the impact of manufacturing errors on their performance. As an illustration, we apply this technology to the design of a two-dimensional photonic crystal structure; the result features a large complete band gap structure and a topology that is different from previously published designs.

  2. Compact nanocavity with elliptical slot inside photonic wire bandgap materials including sidewalls gratings for biosensing

    NASA Astrophysics Data System (ADS)

    Daraei, Ahmadreza; Daraei, Mohammad Esmaeil

    2016-07-01

    In this paper, we introduce and propose a compact and multipurpose one-dimensional photonic crystal silicon wire nanocavity (NC) sensor in silicon-on-insulator wafers. A slot with elliptical cross section (SECS) in the center of the NC together with tapered sidewalls grating of photonic wire (PhWr) provides strongly confined photonic modes for the sensing purposes. We have examined and optimized several geometrical parameters of the PhWr and SECS NC theoretically and computationally. Using finite element method, we have operated our computational validation for the variety of designs. Our results have shown strongly confined photonic mode with high quality ( Q) factor ~1.6 × 104, small modal volume, V mod ~ 0.005( λ/ n)3, as well as high sensitivity as 530 nm/RIU simultaneously operating nearly at the telecom window. These results are promising for refractive index-based sensing, e.g., nanobiomaterials.

  3. Self-assembled quantum dot-sensitized multivalent DNA photonic wires.

    PubMed

    Boeneman, Kelly; Prasuhn, Duane E; Blanco-Canosa, Juan B; Dawson, Philip E; Melinger, Joseph S; Ancona, Mario; Stewart, Michael H; Susumu, Kimihiro; Huston, Alan; Medintz, Igor L

    2010-12-29

    Combining the inherent scaffolding provided by DNA structure with spatial control over fluorophore positioning allows the creation of DNA-based photonic wires with the capacity to transfer excitation energy over distances greater than 150 Å. We demonstrate hybrid multifluorophore DNA-photonic wires that both self-assemble around semiconductor quantum dots (QDs) and exploit their unique photophysical properties. In this architecture, the QDs function as both central nanoscaffolds and ultraviolet energy harvesting donors that drive Förster resonance energy transfer (FRET) cascades through the DNA wires with emissions that approach the near-infrared. To assemble the wires, DNA fragments labeled with a series of increasingly red-shifted acceptor-dyes were hybridized in a predetermined linear arrangement to a complementary DNA template that was chemoselectively modified with a hexahistidine-appended peptide. The peptide portion facilitated metal-affinity coordination of multiple hybridized DNA-dye structures to a central QD completing the final nanocrystal-DNA photonic wire structure. We assembled several such hybrid structures where labeled-acceptor dyes were excited by the QDs and arranged to interact with each other via consecutive FRET processes. The inherently facile reconfiguration properties of this design allowed testing of alternate formats including the addition of an intercalating dye located in the template DNA or placement of multiple identical dye acceptors that engaged in homoFRET. Lastly, a photonic structure linking the central QD with multiple copies of DNA hybridized with 4-sequentially arranged acceptor dyes and demonstrating 4-consecutive energy transfer steps was examined. Step-by-step monitoring of energy transfer with both steady-state and time-resolved spectroscopy allowed efficiencies to be tracked through the structures and suggested that acceptor dye quantum yields are the predominant limiting factor. Integrating such DNA-based photonic

  4. Ultra high quality factor one dimensional photonic crystal/photonic wire micro-cavities in silicon-on-insulator (SOI).

    PubMed

    Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

    2008-08-04

    We present experimental results on photonic crystal/photonic wire micro-cavity structures that demonstrate further enhancement of the quality-factor (Q-factor)--up to approximately 149,000--in the fibre telecommunications wavelength range. The Q-values and the useful transmission levels achieved are due, in particular, to the combination of both tapering within and outside the micro-cavity, with carefully designed hole diameters and non-periodic hole placement within the tapered section. Our 2D Finite Difference Time Domain (FDTD) simulation approach shows good agreement with the experimental results.

  5. Limitations to very high rate wire chambers in fixed target geometries

    SciTech Connect

    Spiegel, L.

    1989-11-01

    The task is to explore physical limitations to the operation of wire chambers in fixed target geometries at an interaction rate of 52 MHz (chosen as it corresponds to the FNAL accelerator rf rate.) That is, to see if there are physical limitations to the operation of gaseous wire chambers at such a high operating rate. A primary proton beam energy of 800 GeV has been assumed although modest increases in the primary energy should not affect the basic conclusion as secondary multiplicity increases logarithmically with center-of-momentum energy. By sustaining a 52 MHz interaction rate it is meant that results from a given interaction are electronically isolated from preceding and subsequent rf buckets, good wire plane efficiency is maintained throughout the active region of the chamber, and the chamber operates in a stable manner throughout the course of a typical fixed target run -- six months to a full year. Other working assumptions include the understanding that chamber electronics -- amplifiers, discriminators, delay elements, encoders -- will not suffer degradation at 52 MHz and that the intensely populated beam regions have been somehow excluded from the chambers. 7 refs., 2 figs.

  6. Air-hole collapse and mode transitions in microstructured fiber photonic wires

    NASA Astrophysics Data System (ADS)

    Mägi, E. C.; Nguyen, H. C.; Eggleton, B. J.

    2005-01-01

    We demonstrate robust, low bend loss photonic wires made from air-clad microstructured “grapefruit” fiber. By tapering the fiber and collapsing the air-holes, the guided mode evolves from being fully embedded within the fiber to a spatially-localized evanescent regime a few millimeters in length, where the mode is strongly influenced by the external environment. We show that in the embedded regime there is negligible loss when the taper is immersed in index-matching fluid, while in the evanescent regime the attenuation increases by over 35 dB. Furthermore, we show that an 11 µm wire in the embedded regime can be bent to a radius as small as 95 µm with bend-loss of 0.03 dB in a 500 nm band. The combination of spatial localization, strong dependence on the external environment andsmall bend radius make the device ideally suited for bio-photonic sensing.

  7. SU-E-T-558: Monte Carlo Photon Transport Simulations On GPU with Quadric Geometry

    SciTech Connect

    Chi, Y; Tian, Z; Jiang, S; Jia, X

    2015-06-15

    Purpose: Monte Carlo simulation on GPU has experienced rapid advancements over the past a few years and tremendous accelerations have been achieved. Yet existing packages were developed only in voxelized geometry. In some applications, e.g. radioactive seed modeling, simulations in more complicated geometry are needed. This abstract reports our initial efforts towards developing a quadric geometry module aiming at expanding the application scope of GPU-based MC simulations. Methods: We defined the simulation geometry consisting of a number of homogeneous bodies, each specified by its material composition and limiting surfaces characterized by quadric functions. A tree data structure was utilized to define geometric relationship between different bodies. We modified our GPU-based photon MC transport package to incorporate this geometry. Specifically, geometry parameters were loaded into GPU’s shared memory for fast access. Geometry functions were rewritten to enable the identification of the body that contains the current particle location via a fast searching algorithm based on the tree data structure. Results: We tested our package in an example problem of HDR-brachytherapy dose calculation for shielded cylinder. The dose under the quadric geometry and that under the voxelized geometry agreed in 94.2% of total voxels within 20% isodose line based on a statistical t-test (95% confidence level), where the reference dose was defined to be the one at 0.5cm away from the cylinder surface. It took 243sec to transport 100million source photons under this quadric geometry on an NVidia Titan GPU card. Compared with simulation time of 99.6sec in the voxelized geometry, including quadric geometry reduced efficiency due to the complicated geometry-related computations. Conclusion: Our GPU-based MC package has been extended to support photon transport simulation in quadric geometry. Satisfactory accuracy was observed with a reduced efficiency. Developments for charged

  8. Cost Effective Open Geometry HTS MRI System amended to BSCCO 2212 Wire for High Field Magnets

    SciTech Connect

    Kennth Marken

    2006-08-11

    The original goal of this Phase II Superconductivity Partnership Initiative project was to build and operate a prototype Magnetic Resonance Imaging (MRI) system using high temperature superconductor (HTS) coils wound from continuously processed dip-coated BSCCO 2212 tape conductor. Using dip-coated tape, the plan was for MRI magnet coils to be wound to fit an established commercial open geometry, 0.2 Tesla permanent magnet system. New electronics and imaging software for a prototype higher field superconducting system would have added significantly to the cost. However, the use of the 0.2 T platform would allow the technical feasibility and the cost issues for HTS systems to be fully established. Also it would establish the energy efficiency and savings of HTS open MRI compared with resistive and permanent magnet systems. The commercial goal was an open geometry HTS MRI running at 0.5 T and 20 K. This low field open magnet was using resistive normal metal conductor and its heat loss was rather high around 15 kolwatts. It was expected that an HTS magnet would dissipate around 1 watt, significantly reduce power consumption. The SPI team assembled to achieve this goal was led by Oxford Instruments, Superconducting Technology (OST), who developed the method of producing commercial dip coated tape. Superconductive Components Inc. (SCI), a leading US supplier of HTS powders, supported the conductor optimization through powder optimization, scaling, and cost reduction. Oxford Magnet Technology (OMT), a joint venture between Oxford Instruments and Siemens and the world’s leading supplier of MRI magnet systems, was involved to design and build the HTS MRI magnet and cryogenics. Siemens Magnetic Resonance Division, a leading developer and supplier of complete MRI imaging systems, was expected to integrate the final system and perform imaging trials. The original MRI demonstration project was ended in July 2004 by mutual consent of Oxford Instruments and Siemens. Between

  9. Characteristics of low-energy ion beams extracted from a wire electrode geometry.

    PubMed

    Vasquez, M; Tokumura, S; Kasuya, T; Maeno, S; Wada, M

    2012-02-01

    Beams of argon ions with energies less than 50 eV were extracted from an ion source through a wire electrode extractor geometry. A retarding potential energy analyzer (RPEA) was constructed in order to characterize the extracted ion beams. The single aperture RPEA was used to determine the ion energy distribution function, the mean ion energy and the ion beam energy spread. The multi-cusp hot cathode ion source was capable of producing a low electron temperature gas discharge to form quiescent plasmas from which ion beam energy as low as 5 eV was realized. At 50 V extraction potential and 0.1 A discharge current, the ion beam current density was around 0.37 mA/cm(2) with an energy spread of 3.6 V or 6.5% of the mean ion energy. The maximum ion beam current density extracted from the source was 0.57 mA/cm(2) for a 50 eV ion beam and 1.78 mA/cm(2) for a 100 eV ion beam.

  10. Radiation characteristics of selected long wire antennas as a function of geometry using computer modeling techniques

    NASA Astrophysics Data System (ADS)

    Gillespie, Robert J., Sr.

    1986-12-01

    This thesis, sponsored by the Marine Corps Development and Education Command, Quantico, Va., examines the far field patterns of five high frequency long wire antenna configurations through the use of the Numerical Electromagnetics Code (NEC). Lossy ground and the effects of variations made to these structures are considered. The resulting far field patterns are contained in the appendix. The antenna configurations vary in length from 1.87 to 17.19 wavelengths and in their height above ground from 0.103 to 0.610 wavelengths. Variations in the antennas end-regions include: the use of a ground rod or radial screen attached to the transmitter, terminating the far end of the antenna, and varying the shape of the transmitter from a small box (radio-sized) to a large (vehicle-sized) configuration. It is concluded that both the antenna height and length determine the far field geometry, and that end-region variations also impact, though to a lesser degree, on the pattern. Tables of comparative results are provided.

  11. Achieving effective terminal exciton delivery in quantum dot antenna-sensitized multistep DNA photonic wires.

    PubMed

    Spillmann, Christopher M; Ancona, Mario G; Buckhout-White, Susan; Algar, W Russ; Stewart, Michael H; Susumu, Kimihiro; Huston, Alan L; Goldman, Ellen R; Medintz, Igor L

    2013-08-27

    Assembling DNA-based photonic wires around semiconductor quantum dots (QDs) creates optically active hybrid architectures that exploit the unique properties of both components. DNA hybridization allows positioning of multiple, carefully arranged fluorophores that can engage in sequential energy transfer steps while the QDs provide a superior energy harvesting antenna capacity that drives a Förster resonance energy transfer (FRET) cascade through the structures. Although the first generation of these composites demonstrated four-sequential energy transfer steps across a distance >150 Å, the exciton transfer efficiency reaching the final, terminal dye was estimated to be only ~0.7% with no concomitant sensitized emission observed. Had the terminal Cy7 dye utilized in that construct provided a sensitized emission, we estimate that this would have equated to an overall end-to-end ET efficiency of ≤ 0.1%. In this report, we demonstrate that overall energy flow through a second generation hybrid architecture can be significantly improved by reengineering four key aspects of the composite structure: (1) making the initial DNA modification chemistry smaller and more facile to implement, (2) optimizing donor-acceptor dye pairings, (3) varying donor-acceptor dye spacing as a function of the Förster distance R0, and (4) increasing the number of DNA wires displayed around each central QD donor. These cumulative changes lead to a 2 orders of magnitude improvement in the exciton transfer efficiency to the final terminal dye in comparison to the first-generation construct. The overall end-to-end efficiency through the optimized, five-fluorophore/four-step cascaded energy transfer system now approaches 10%. The results are analyzed using Förster theory with various sources of randomness accounted for by averaging over ensembles of modeled constructs. Fits to the spectra suggest near-ideal behavior when the photonic wires have two sequential acceptor dyes (Cy3 and Cy3.5) and

  12. Spiral-path high-sensitivity silicon photonic wire molecular sensor with temperature-independent response.

    PubMed

    Densmore, A; Xu, D-X; Janz, S; Waldron, P; Mischki, T; Lopinski, G; Delâge, A; Lapointe, J; Cheben, P; Lamontagne, B; Schmid, J H

    2008-03-15

    We demonstrate a new silicon photonic wire waveguide evanescent field (PWEF) sensor that exploits the strong evanescent field of the transverse magnetic mode of this high-index-contrast, submicrometer-dimension waveguide. High sensitivity is achieved by using a 2 mm long double-spiral waveguide structure that fits within a compact circular area of 150 microm diameter, facilitating compatibility with commercial spotting apparatus and the fabrication of densely spaced sensor arrays. By incorporating the PWEF sensor element into a balanced waveguide Mach-Zehnder interferometer circuit, a minimum detectable mass of approximately 10 fg of streptavidin protein is demonstrated with near temperature-independent response.

  13. A Miniaturized Linear Wire Ion Trap with Electron Ionization and Single Photon Ionization Sources

    NASA Astrophysics Data System (ADS)

    Wu, Qinghao; Tian, Yuan; Li, Ailin; Andrews, Derek; Hawkins, Aaron R.; Austin, Daniel E.

    2017-05-01

    A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power. Under optimized conditions, the limit of detection (LOD) for benzene was 80 ppbv using SPI, better than the LOD using EI (137 ppbv). System performance was demonstrated by distinguishing compounds in different classes from gasoline.

  14. A Miniaturized Linear Wire Ion Trap with Electron Ionization and Single Photon Ionization Sources

    NASA Astrophysics Data System (ADS)

    Wu, Qinghao; Tian, Yuan; Li, Ailin; Andrews, Derek; Hawkins, Aaron R.; Austin, Daniel E.

    2017-01-01

    A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power. Under optimized conditions, the limit of detection (LOD) for benzene was 80 ppbv using SPI, better than the LOD using EI (137 ppbv). System performance was demonstrated by distinguishing compounds in different classes from gasoline.

  15. Photonic wire biosensor microarray chip and instrumentation with application to serotyping of Escherichia coli isolates.

    PubMed

    Janz, S; Xu, D-X; Vachon, M; Sabourin, N; Cheben, P; McIntosh, H; Ding, H; Wang, S; Schmid, J H; Delâge, A; Lapointe, J; Densmore, A; Ma, R; Sinclair, W; Logan, S M; Mackenzie, R; Liu, Q Y; Zhang, D; Lopinski, G; Mozenson, O; Gilmour, M; Tabor, H

    2013-02-25

    A complete photonic wire molecular biosensor microarray chip architecture and supporting instrumentation is described. Chip layouts with 16 and 128 independent sensors have been fabricated and tested, where each sensor can provide an independent molecular binding curve. Each sensor is 50 μm in diameter, and consists of a millimeter long silicon photonic wire waveguide folded into a spiral ring resonator. An array of 128 sensors occupies a 2 × 2 mm2 area on a 6 × 9 mm2 chip. Microfluidic sample delivery channels are fabricated monolithically on the chip. The size and layout of the sensor array is fully compatible with commercial spotting tools designed to independently functionalize fluorescence based biochips. The sensor chips are interrogated using an instrument that delivers sample fluid to the chip and is capable of acquiring up to 128 optical sensor outputs simultaneously and in real time. Coupling light from the sensor chip is accomplished through arrays of sub-wavelength surface grating couplers, and the signals are collected by a fixed two-dimensional detector array. The chip and instrument are designed so that connection of the fluid delivery system and optical alignment are automated, and can be completed in a few seconds with no active user input. This microarray system is used to demonstrate a multiplexed assay for serotyping E. coli bacteria using serospecific polyclonal antibody probe molecules.

  16. Role of geometry in the superfluid flow of nonlocal photon fluids

    NASA Astrophysics Data System (ADS)

    Vocke, David; Wilson, Kali; Marino, Francesco; Carusotto, Iacopo; Wright, Ewan M.; Roger, Thomas; Anderson, Brian P.; Öhberg, Patrik; Faccio, Daniele

    2016-07-01

    Recent work has unveiled a new class of optical systems that can exhibit the characteristic features of superfluidity. One such system relies on the repulsive photon-photon interaction that is mediated by a thermal optical nonlinearity and is therefore inherently nonlocal due to thermal diffusion. Here we investigate how such a nonlocal interaction, which at a first inspection would not be expected to lead to superfluid behavior, may be tailored by acting upon the geometry of the photon fluid itself. Our models and measurements show that restricting the laser profile and hence the photon fluid to a strongly elliptical geometry modifies thermal diffusion along the major beam axis and reduces the effective nonlocal interaction length by two orders of magnitude. This in turn enables the system to display a characteristic trait of superfluid flow: the nucleation of quantized vortices in the flow past an extended physical obstacle. These results are general and apply to other nonlocal fluids, such as dipolar Bose-Einstein condensates, and show that "thermal" photon superfluids provide an exciting and novel experimental environment for probing the nature of superfluidity, with applications to the study of quantum turbulence and analog gravity.

  17. Topology optimized mode multiplexing in silicon-on-insulator photonic wire waveguides.

    PubMed

    Frellsen, Louise F; Ding, Yunhong; Sigmund, Ole; Frandsen, Lars H

    2016-07-25

    We design and experimentally verify a topology optimized low-loss and broadband two-mode (de-)multiplexer, which is (de-)multiplexing the fundamental and the first-order transverse-electric modes in a silicon photonic wire. The device has a footprint of 2.6 µm x 4.22 µm and exhibits a loss <1.2 dB in a 100 nm bandwidth measured around 1570 nm. The measured cross talk is <-12 dB and the extinction ratio is >14 dB in the C-band. Furthermore, we demonstrate that the design method can be expanded to include more modes, in this case including also the second order transverse-electric mode, while maintaining functionality.

  18. Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection.

    PubMed

    Densmore, A; Vachon, M; Xu, D-X; Janz, S; Ma, R; Li, Y-H; Lopinski, G; Delâge, A; Lapointe, J; Luebbert, C C; Liu, Q Y; Cheben, P; Schmid, J H

    2009-12-01

    We demonstrate a silicon photonic wire waveguide biosensor array chip for the simultaneous monitoring of different molecular binding reactions. The chip is compatible with automated commercial spotting tools and contains a monolithically integrated microfluidic channel for sample delivery. Each array sensor element is a 1.8-mm-long spiral waveguide folded within a 130 microm diameter spot and is incorporated in a balanced Mach-Zehnder interferometer with a near temperature independent response. The sensors are arranged in a 400 microm spacing grid pattern and are addressed through cascaded 1x2 optical power splitters using light from a single input fiber. We demonstrate the real-time monitoring of antibody-antigen reactions using complementary and mismatched immunoglobulin G receptor-analyte pairs and bovine serum albumin. The measured level of detection for each sensor element corresponds to a surface coverage of less than 0.3 pg/mm(2).

  19. All-optical switching in silicon-on-insulator photonic wire nano-cavities.

    PubMed

    Belotti, Michele; Galli, Matteo; Gerace, Dario; Andreani, Lucio Claudio; Guizzetti, Giorgio; Md Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

    2010-01-18

    We report on experimental demonstration of all-optical switching in a silicon-on-insulator photonic wire nanocavity operating at telecom wavelengths. The switching is performed with a control pulse energy as low as approximately 0.1 pJ on a cavity device that presents very high signal transmission, an ultra-high quality-factor, almost diffraction-limited modal volume and a footprint of only 5 microm(2). High-speed modulation of the cavity mode is achieved by means of optical injection of free carriers using a nanosecond pulsed laser. Experimental results are interpreted by means of finite-difference time-domain simulations. The possibility of using this device as a logic gate is also demonstrated.

  20. SABRINA - An interactive geometry modeler for MCNP (Monte Carlo Neutron Photon)

    SciTech Connect

    West, J.T.; Murphy, J.

    1988-01-01

    SABRINA is an interactive three-dimensional geometry modeler developed to produce complicated models for the Los Alamos Monte Carlo Neutron Photon program MCNP. SABRINA produces line drawings and color-shaded drawings for a wide variety of interactive graphics terminals. It is used as a geometry preprocessor in model development and as a Monte Carlo particle-track postprocessor in the visualization of complicated particle transport problem. SABRINA is written in Fortran 77 and is based on the Los Alamos Common Graphics System, CGS. 5 refs., 2 figs.

  1. Tunable polarization filter based on high-birefringence photonic crystal fiber filled with silver wires

    NASA Astrophysics Data System (ADS)

    Yang, Xianchao; Lu, Ying; Liu, Baolin; Yao, Jianquan

    2017-07-01

    A tunable single polarization filter based on high-birefringence photonic crystal fiber with silver wires symmetrically filled into cladding air holes is designed. The confinement loss of the unwanted polarized mode (x-polarized mode) at 1310- and 1550-nm bands are 371 and 252 dB/cm, whereas another mode confinement loss (y-polarized mode) at the corresponding wavelength as low as 14 and 10 dB/cm, respectively. Moreover, the 20-dB bandwidth can reach 179 (at the 1310-nm band) and 71 nm (at the 1550-nm band) for a propagation distance of 1 mm. The dispersion relations and polarization characteristics are analyzed in detail utilizing the finite element method. Numerical results show that by adjusting the pitch between two adjacent air holes, the diameters of cladding air holes or silver wires near the fiber core, the resonance wavelength and resonance strength can be tuned effectively, which is beneficial for tunable polarization filter devices in the communication wave bands.

  2. Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

    NASA Astrophysics Data System (ADS)

    Azzini, Stefano; Grassani, Davide; Galli, Matteo; Gerace, Dario; Patrini, Maddalena; Liscidini, Marco; Velha, Philippe; Bajoni, Daniele

    2013-07-01

    We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitude. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators.

  3. Virtual photons in imaginary time: Computing Casimir forces in new geometries

    NASA Astrophysics Data System (ADS)

    Johnson, Steven G.

    2009-03-01

    One of the most dramatic manifestations of the quantum nature of light in the past half-century has been the Casimir force: a force between neutral objects at close separations caused by quantum vacuum fluctuations in the electromagnetic fields. In classical photonics, wavelength-scale structures can be designed to dramatically alter the behavior of light, so it is natural to consider whether analogous geometry-based effects occur for Casimir forces. However, this problem turns out to be surprisingly difficult for all but the simplest planar geometries. (The deceptively simple case of an infinite plate and infinite cylinder, for perfect metals, was first solved in 2006.) Many formulations of the Casimir force, indeed, correspond to impossibly hard numerical problems. We will describe how the availability of large-scale computing resources in NSF's Teragrid, combined with reformulations of the Casimir-force problem oriented towards numerical computation, are enabling the exploration of Casimir forces in new regimes of geometry and materials.

  4. Photon extremity absorbed dose and kerma conversion coefficients for calibration geometries.

    PubMed

    Veinot, K G; Hertel, N E

    2007-02-01

    Absorbed dose and dose equivalent conversion coefficients are routinely used in personnel dosimetry programs. These conversion coefficients can be applied to particle fluences or to measured air kerma values to determine appropriate operational monitoring quantities such as the ambient dose equivalent or personal dose equivalent for a specific geometry. For personnel directly handling materials, the absorbed dose to the extremities is of concern. This work presents photon conversion coefficients for two extremity calibration geometries using finger and wrist/arm phantoms described in HPS N13.32. These conversion coefficients have been calculated as a function of photon energy in terms of the kerma and the absorbed dose using Monte Carlo techniques and the calibration geometries specified in HPS N13.32. Additionally, kerma and absorbed dose conversion coefficients for commonly used x-ray spectra and calibration source fields are presented. The kerma values calculated in this work for the x-ray spectra and calibration sources compare well to those listed in HPS N13.32. The absorbed dose values, however, differ significantly for higher energy photons because charged particle equilibrium conditions have not been satisfied for the shallow depth. Thus, the air-kerma-to-dose and exposure-to-dose conversion coefficients for Cs and Co listed in HPS N13.32 overestimate the absorbed dose to the extremities. Applying the conversion coefficients listed in HPS N13.32 for Cs, for example, would result in an overestimate of absorbed dose of 62% for the finger phantom and 55% for the wrist phantom.

  5. Low frequency magneto-impedance effects in electrode-posited multilayer [Ni80Fe20/Cu]3 on Cu-wire substrates with different sample geometry

    NASA Astrophysics Data System (ADS)

    Wicaksono, B. Anggit; Nahrun, Ahmad Asrori; Nuryani, Purnama, Budi

    2016-02-01

    Magneto-impedance (MI) multilayer [Ni80Fe20 (800 nm)/Cu (300 nm)]3 in Cu wire has been modified in its geometric shapes. The Multilayer is the result of electro-deposition with Pt (platinum) as the electrode. This study shows that the MI ratio changes to the geometry of the sample. The geometry modification increases the MI ratio of 54.35% (wire shape) amounted to 70.53% (solenoid shape); it is measured at a frequency of 100 kHz. The modification also increase the sensitivity sensor magnetic from 9.05%/mT to 12.82%/mT.

  6. The effect of geometry of composite MgB 2/stainless-steel (SS) wires fabricated by PIT process on the superconducting properties

    NASA Astrophysics Data System (ADS)

    Song, K. J.; Kim, S. W.; Park, C.; Joo, J. H.; Choi, S. J.; Ko, R. K.; Ha, H. S.; Ha, D. W.; Oh, S. S.

    2004-08-01

    Single-, multi-, and two kinds of coaxial-filament composite MgB 2/SS-SS (stainless steel for both outer and inner tubes) and MgB 2/SS-Cu (stainless steel for outer tube and copper for inner tube) wires were successfully fabricated using powder-in-tube (PIT) process with swaging only. The effect of the geometries of the MgB 2 PIT wires has been studied comparatively. The isothermal magnetizations M( H) for both the sintered and the as-rolled single-, multi-, and coaxial-filament MgB 2 wires were measured at temperatures between 5 and 50 K in fields up to 5 T. The critical current density was estimated by the M( H) data using Bean model. The coaxial-filament composite MgB 2 wires showed much better Jc than both the single- and the multi-filament composite ones. The results of this study show that the superconducting properties of the MgB 2 PIT wires/tapes can improve by employing better geometries such as the coaxial-filament composite MgB 2/SS-SS wires.

  7. From monomers to geometry-constrained molecules: one step further toward cyanide bridged wires.

    PubMed

    Alborés, Pablo; Slep, Leonardo D; Eberlin, Livia S; Corilo, Yuri E; Eberlin, Marcos N; Benítez, Guillermo; Vela, Maria E; Salvarezza, Roberto C; Baraldo, Luis M

    2009-12-07

    We report on the synthesis and properties of a family of linear cyanide bridged mixed-valence heptanuclear complexes with the formula: trans-[L(4)Ru(II){(mu-NC)Fe(III)(NC)(4)(mu-CN)Ru(II)L'(4)(mu-NC)Fe(III)(CN)(5)}(2)](6-) (with L and L' a para substituted pyridine). We also report on the properties of a related pentanuclear complex. These oligomers were purified by size exclusion chromatography, characterized by electrospray ionization (ESI) mass spectrometry and elemental analysis, and their linear shape was confirmed by scanning tunneling microscopy (STM). These complexes present a rich electrochemistry associated with the seven redox active centers. The redox potential split of identical fragments indicates that there is considerable communication along the cyanide bridged backbone of the compounds, even for centers more than 3 nm apart. This small attenuation of the interaction at long distances make these cyanide bridged compounds good candidates for molecular wires. Interestingly, the extent of the communication depends on the relative energy of the fragments, as evaluated by their redox potentials, providing a guide for improvement of this interesting property.

  8. Investigation of Magnetic Field Geometry in Exploding Wire Z-Pinches via Proton Deflectometry

    NASA Astrophysics Data System (ADS)

    Mariscal, Derek; Beg, Farhat; Wei, Mingsheng; Chittenden, Jeremy; Presura, Radu

    2012-10-01

    It is often difficult to determine the configuration of B-fields within z-pinch plasma systems. Typical laser probing diagnostics are limited by the critical density, and electrical diagnostics are prone to failure as well as perturbation of the system. The use of proton beams launched by high intensity lasers, and the subsequent tracking of their deflected trajectories, will enable access to field measurements in previously inaccessible plasma densities.The experimental testing of this method is performed at the Nevada Test Facility (NTF) using the 10J 0.3ps Leopard laser coupled to the 1.6MA ZEBRA pulsed power generator. MHD simulations of the z-pinch plasmas are performed with the 3D resistive MHD code, GORGON. Protons are then injected and tracked through the plasma using the 3D PIC Large Scale Plasma code in order to produce possible proton image plane data. The first computational demonstration of protons propagating through single wire and x-pinch plasmas, along with comparison to recent experimental data will be presented.

  9. TART97 a coupled neutron-photon 3-D, combinatorial geometry Monte Carlo transport code

    SciTech Connect

    Cullen, D.E.

    1997-11-22

    TART97 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo transport code. This code can on any modern computer. It is a complete system to assist you with input preparation, running Monte Carlo calculations, and analysis of output results. TART97 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART97 is distributed on CD. This CD contains on- line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART97 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART97 and its data riles.

  10. Differences in the effects of turns and constrictions on the resistive response in current-biased superconducting wire after single photon absorption

    NASA Astrophysics Data System (ADS)

    Zotova, A. N.; Y Vodolazov, D.

    2013-07-01

    We study how turns and constrictions affect the resistive response of superconducting wire after instantaneous, localized heating, by modeling the absorption of a single photon by the wire. We find that the presence of constrictions favors the detection of photons with a range of energies whereas the presence of turns increases the ability to detect only relatively ‘low’ energy photons. The main reason is that in the case of a constriction the current density is increased over the whole length and width of the constriction while in the case of a turn the current density is enhanced only near the inner corner of the turn. This results in inhomogeneous Joule heating near the turn and worsens the conditions for the appearance of the normal domain at relatively small currents, where the ‘high’ energy photons could already create a normal domain in the straight part of the wire. We also find that the amplitude of the voltage pulse depends on the location at which the photon is absorbed, being smallest when the photon is absorbed near the turn and largest when the photon is absorbed near the constriction. This effect is due to the difference in the resistance of constrictions and turns in the normal state from the resistance of the rest of the wire.

  11. Organ and effective dose coefficients for cranial and caudal irradiation geometries: photons

    SciTech Connect

    Veinot, K. G.; Eckerman, K. F.; Hertel, N. E.

    2015-05-02

    With the introduction of new recommendations of the International Commission on Radiological Protection (ICRP) in Publication 103, the methodology for determining the protection quantity, effective dose, has been modified. The modifications include changes to the defined organs and tissues, the associated tissue weighting factors, radiation weighting factors and the introduction of reference sex-specific computational phantoms. Computations of equivalent doses in organs and tissues are now performed in both the male and female phantoms and the sex-averaged values used to determine the effective dose. Dose coefficients based on the ICRP 103 recommendations were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57. The coefficients were determined for the following irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), right and left lateral (RLAT and LLAT), rotational (ROT) and isotropic (ISO). In this work, the methodology of ICRP Publication 116 was used to compute dose coefficients for photon irradiation of the body with parallel beams directed upward from below the feet (caudal) and directed downward from above the head (cranial). These geometries may be encountered in the workplace from personnel standing on contaminated surfaces or volumes and from overhead sources. Calculations of organ and tissue kerma and absorbed doses for caudal and cranial exposures to photons ranging in energy from 10 keV to 10 GeV have been performed using the MCNP6.1 radiation transport code and the adult reference phantoms of ICRP Publication 110. As with calculations reported in ICRP 116, the effects of charged-particle transport are evident when compared with values obtained by using the kerma approximation. At lower energies the effective dose per particle fluence for cranial and caudal exposures is less than AP orientations while above similar to 30 MeV the cranial and caudal values are greater.

  12. Organ and effective dose coefficients for cranial and caudal irradiation geometries: photons.

    PubMed

    Veinot, K G; Eckerman, K F; Hertel, N E

    2016-02-01

    With the introduction of new recommendations of the International Commission on Radiological Protection (ICRP) in Publication 103, the methodology for determining the protection quantity, effective dose, has been modified. The modifications include changes to the defined organs and tissues, the associated tissue weighting factors, radiation weighting factors and the introduction of reference sex-specific computational phantoms. Computations of equivalent doses in organs and tissues are now performed in both the male and female phantoms and the sex-averaged values used to determine the effective dose. Dose coefficients based on the ICRP 103 recommendations were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57. The coefficients were determined for the following irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), right and left lateral (RLAT and LLAT), rotational (ROT) and isotropic (ISO). In this work, the methodology of ICRP Publication 116 was used to compute dose coefficients for photon irradiation of the body with parallel beams directed upward from below the feet (caudal) and directed downward from above the head (cranial). These geometries may be encountered in the workplace from personnel standing on contaminated surfaces or volumes and from overhead sources. Calculations of organ and tissue kerma and absorbed doses for caudal and cranial exposures to photons ranging in energy from 10 keV to 10 GeV have been performed using the MCNP6.1 radiation transport code and the adult reference phantoms of ICRP Publication 110. As with calculations reported in ICRP 116, the effects of charged-particle transport are evident when compared with values obtained by using the kerma approximation. At lower energies the effective dose per particle fluence for cranial and caudal exposures is less than AP orientations while above ∼30 MeV the cranial and caudal values are greater. Published by Oxford University

  13. Organ and effective dose coefficients for cranial and caudal irradiation geometries: photons

    DOE PAGES

    Veinot, K. G.; Eckerman, K. F.; Hertel, N. E.

    2015-05-02

    With the introduction of new recommendations of the International Commission on Radiological Protection (ICRP) in Publication 103, the methodology for determining the protection quantity, effective dose, has been modified. The modifications include changes to the defined organs and tissues, the associated tissue weighting factors, radiation weighting factors and the introduction of reference sex-specific computational phantoms. Computations of equivalent doses in organs and tissues are now performed in both the male and female phantoms and the sex-averaged values used to determine the effective dose. Dose coefficients based on the ICRP 103 recommendations were reported in ICRP Publication 116, the revision ofmore » ICRP Publication 74 and ICRU Publication 57. The coefficients were determined for the following irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), right and left lateral (RLAT and LLAT), rotational (ROT) and isotropic (ISO). In this work, the methodology of ICRP Publication 116 was used to compute dose coefficients for photon irradiation of the body with parallel beams directed upward from below the feet (caudal) and directed downward from above the head (cranial). These geometries may be encountered in the workplace from personnel standing on contaminated surfaces or volumes and from overhead sources. Calculations of organ and tissue kerma and absorbed doses for caudal and cranial exposures to photons ranging in energy from 10 keV to 10 GeV have been performed using the MCNP6.1 radiation transport code and the adult reference phantoms of ICRP Publication 110. As with calculations reported in ICRP 116, the effects of charged-particle transport are evident when compared with values obtained by using the kerma approximation. At lower energies the effective dose per particle fluence for cranial and caudal exposures is less than AP orientations while above similar to 30 MeV the cranial and caudal values are greater.« less

  14. Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors

    SciTech Connect

    Lusche, R. Semenov, A.; Ilin, K.; Siegel, M.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Goltsman, G.; Vodolazov, D.; Hübers, H.-W.

    2014-07-28

    A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model.

  15. Why diamond dimensions and electrode geometry are crucial for small photon beam dosimetry

    SciTech Connect

    Marsolat, F.; Tromson, D.; Tranchant, N.; Pomorski, M.; Bergonzo, P.; Bassinet, C.; Huet, C.; Buchheit, I.; Marchesi, V.; Gaudaire-Josset, S.; Lisbona, A.; Lazaro, D.; Hugon, R.

    2015-12-21

    Recent use of very small photon beams (down to 4 mm) in stereotactic radiotherapy requires new detectors to accurately determine the delivered dose. Diamond detectors have been presented in the literature as an attractive candidate for this application, due to their small detection volume and the diamond atomic number (Z = 6) which is close to water effective atomic number (Zeff ∼ 7.42). However, diamond exhibits a density 3.51 times greater than that of water and recent studies using Monte Carlo simulations have demonstrated the drawback of a high-density detector on small beam output factors. The current study focuses on geometrical parameters of diamond detector, namely, the diamond dimensions and the electrode geometry, in order to solve the dosimetric issues still observed in small photon beams with diamond detectors. To give better insights to these open questions, we have used both computational method and experimental analysis. This study highlighted that reducing diamond dimensions is crucial for small beam output factor measurements and to limit the influence of its high density. Furthermore, electrodes covering the whole diamond surface were essential for a dose rate independence of the diamond detector. The optimal dosimeter derived from this work presented small diamond dimensions of approximately 1 × 1 × 0.15 mm{sup 3}, with diamond-like-carbon electrodes covering the whole diamond surface. A dose rate independence of this diamond detector (better than 0.5% over a wide range of dose rates available on a stereotactic dedicated facility) was obtained due to the electrode geometry. Concerning the output factor measurements, a good agreement (better than 1.1%) was observed between this carbon material detector and two types of passive dosimeters (LiF microcubes and EBT2 radiochromic films) for all beam sizes except the smallest field of 0.6 × 0.6 cm{sup 2} with a deviation of 2.6%. This new study showed the high performance

  16. Compact, lower-power-consumption wavelength tunable laser fabricated with silicon photonic-wire waveguide micro-ring resonators.

    PubMed

    Chu, Tao; Fujioka, Nobuhide; Ishizaka, Masashige

    2009-08-03

    A wavelength tunable laser with an SOA and external double micro-ring resonator, which is fabricated with silicon photonic-wire waveguides, is demonstrated. To date, it is the first wavelength tunable laser fabricated with silicon photonic technology. The device is ultra compact, and its external resonator footprint is 700 x 450 microm, which is about 1/25 that of conventional tunable lasers fabricated with SiON waveguides. The silicon resonator shows a wide tuning range covering the C or L bands for DWDM optical communication. We obtained a maximum tuning span of 38 nm at a tuning power consumption of 26 mW, which is about 1/8 that of SiON-type resonators.

  17. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: a peculiar role of geometry.

    PubMed

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D(6h) point group symmetry versus ovalene with D(2h) symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D(6h) group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D(2h) ovalene but not in those with D(6h) symmetry.

  18. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    SciTech Connect

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D{sub 6h} point group symmetry versus ovalene with D{sub 2h} symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D{sub 6h} group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D{sub 2h} ovalene but not in those with D{sub 6h} symmetry.

  19. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    NASA Astrophysics Data System (ADS)

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-03-01

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D6h point group symmetry versus ovalene with D2h symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D6h group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D2h ovalene but not in those with D6h symmetry.

  20. Effects of system geometry and other physical factors on photon sensitivity of high-resolution positron emission tomography

    PubMed Central

    Foudray, A M K; Olcott, P D

    2013-01-01

    We are studying two new detector technologies that directly measure the three-dimensional coordinates of 511 keV photon interactions for high-resolution positron emission tomography (PET) systems designed for small animal and breast imaging. These detectors are based on (1) lutetium oxyorthosilicate (LSO) scintillation crystal arrays coupled to position-sensitive avalanche photodiodes (PSAPD) and (2) cadmium zinc telluride (CZT). The detectors have excellent measured 511 keV photon energy resolutions (≤12% FWHM for LSO-PSAPD and ≤3% for CZT) and good coincidence time resolutions (2 ns FWHM for LSO-PSAPD and 8 ns for CZT). The goal is to incorporate the detectors into systems that will achieve 1 mm3 spatial resolution (~1 mm3, uniform throughout the field of view (FOV)), with excellent contrast resolution as well. In order to realize 1 mm3 spatial resolution with high signal-to-noise ratio (SNR), it is necessary to significantly boost coincidence photon detection efficiency (referred to as photon sensitivity). To facilitate high photon sensitivity in the proposed PET system designs, the detector arrays are oriented ‘edge-on’ with respect to incoming 511 keV annihilation photons and arranged to form a compact FOV with detectors very close to, or in contact with, the subject tissues. In this paper, we used Monte Carlo simulation to study various factors that limit the photon sensitivity of a high-resolution PET system dedicated to small animal imaging. To optimize the photon sensitivity, we studied several possible system geometries for a fixed 8 cm transaxial and 8 cm axial FOV. We found that using rectangular-shaped detectors arranged into a cylindrical geometry does not yield the best photon sensitivity. This is due to the fact that forming rectangular-shaped detectors into a ring produces significant wedge-shaped inter-module gaps, through which Compton-scattered photons in the detector can escape. This effect limits the center point source photon

  1. Effects of system geometry and other physical factors on photon sensitivity of high-resolution positron emission tomography.

    PubMed

    Habte, F; Foudray, A M K; Olcott, P D; Levin, C S

    2007-07-07

    We are studying two new detector technologies that directly measure the three-dimensional coordinates of 511 keV photon interactions for high-resolution positron emission tomography (PET) systems designed for small animal and breast imaging. These detectors are based on (1) lutetium oxyorthosilicate (LSO) scintillation crystal arrays coupled to position-sensitive avalanche photodiodes (PSAPD) and (2) cadmium zinc telluride (CZT). The detectors have excellent measured 511 keV photon energy resolutions (photon detection efficiency (referred to as photon sensitivity). To facilitate high photon sensitivity in the proposed PET system designs, the detector arrays are oriented 'edge-on' with respect to incoming 511 keV annihilation photons and arranged to form a compact FOV with detectors very close to, or in contact with, the subject tissues. In this paper, we used Monte Carlo simulation to study various factors that limit the photon sensitivity of a high-resolution PET system dedicated to small animal imaging. To optimize the photon sensitivity, we studied several possible system geometries for a fixed 8 cm transaxial and 8 cm axial FOV. We found that using rectangular-shaped detectors arranged into a cylindrical geometry does not yield the best photon sensitivity. This is due to the fact that forming rectangular-shaped detectors into a ring produces significant wedge-shaped inter-module gaps, through which Compton-scattered photons in the detector can escape. This effect limits the center point source

  2. Penetration depth of photons in biological tissues from hyperspectral imaging in shortwave infrared in transmission and reflection geometries

    NASA Astrophysics Data System (ADS)

    Zhang, Hairong; Salo, Daniel; Kim, David M.; Komarov, Sergey; Tai, Yuan-Chuan; Berezin, Mikhail Y.

    2016-12-01

    Measurement of photon penetration in biological tissues is a central theme in optical imaging. A great number of endogenous tissue factors such as absorption, scattering, and anisotropy affect the path of photons in tissue, making it difficult to predict the penetration depth at different wavelengths. Traditional studies evaluating photon penetration at different wavelengths are focused on tissue spectroscopy that does not take into account the heterogeneity within the sample. This is especially critical in shortwave infrared where the individual vibration-based absorption properties of the tissue molecules are affected by nearby tissue components. We have explored the depth penetration in biological tissues from 900 to 1650 nm using Monte-Carlo simulation and a hyperspectral imaging system with Michelson spatial contrast as a metric of light penetration. Chromatic aberration-free hyperspectral images in transmission and reflection geometries were collected with a spectral resolution of 5.27 nm and a total acquisition time of 3 min. Relatively short recording time minimized artifacts from sample drying. Results from both transmission and reflection geometries consistently revealed that the highest spatial contrast in the wavelength range for deep tissue lies within 1300 to 1375 nm however, in heavily pigmented tissue such as the liver, the range 1550 to 1600 nm is also prominent.

  3. Convergence of shock waves generated by underwater electrical explosion of cylindrical wire arrays between different boundary geometries

    SciTech Connect

    Yanuka, D.; Zinowits, H. E.; Krasik, Ya. E.; Kozlov, M.

    2015-10-15

    The results of experiments and numerical simulations of a shock wave propagating between either conical or parabolic bounding walls are presented. The shock wave was generated by a microsecond timescale underwater electrical explosion of a cylindrical wire array supplied by a current pulse having an amplitude of ∼230 kA and a rise time of ∼1 μs. It is shown that with the same energy density deposition into the exploding wire array, the shock wave converges faster between parabolic walls, and as a result, the pressure in the vicinity of convergence is ∼2.3 times higher than in the case of conical walls. The results obtained are compared to those of earlier experiments [Antonov et al., Appl. Phys. Lett. 102, 124104 (2013)] with explosions of spherical wire arrays. It is shown that at a distance of ∼400 μm from the implosion origin the pressure obtained in the current experiments is higher than for the case of spherical wire arrays.

  4. One-dimensional photonic crystals with highly Bi-substituted iron garnet defect in reflection polar geometry

    NASA Astrophysics Data System (ADS)

    Mikhailova, T. V.; Berzhansky, V. N.; Karavainikov, A. V.; Shaposhnikov, A. N.; Prokopov, A. R.; Lyashko, S. D.

    2016-08-01

    It is represented the results of modelling of magnetooptical properties in reflection polar geometry of one-dimensional photonic crystal, in which highly Bi-substituted iron garnet defect of composition Bi1.0Y0.5Gd1.5Fe4.2Al0.8O12 / Bi2.8Y0.2Fe5Oi2 is located between the dielectric Bragg mirrors (SiO2 / TiO2)m (were m is number of layer pairs) and buffer SiO2 and gold top layers of different thicknesses is placed on structure. The modification of spectral line- shapes of microcavity and Tamm plasmon-polariton modes depending on m is found.

  5. TART 2000: A Coupled Neutron-Photon, 3-D, Combinatorial Geometry, Time Dependent, Monte Carlo Transport Code

    SciTech Connect

    Cullen, D.E

    2000-11-22

    TART2000 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input Preparation, running Monte Carlo calculations, and analysis of output results. TART2000 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART2000 is distributed on CD. This CD contains on-line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART2000 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART2000 and its data files.

  6. TART98 a coupled neutron-photon 3-D, combinatorial geometry time dependent Monte Carlo Transport code

    SciTech Connect

    Cullen, D E

    1998-11-22

    TART98 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input preparation, running Monte Carlo calculations, and analysis of output results. TART98 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART98 is distributed on CD. This CD contains on-line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART98 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART98 and its data files.

  7. Enhanced geometries of macroporous silicon photonic crystals for optical gas sensing applications

    NASA Astrophysics Data System (ADS)

    Cardador, D.; Vega, D.; Segura, D.; Trifonov, T.; Rodríguez, A.

    2017-07-01

    A macroporous silicon photonic crystal is designed and optimized theoretically for its use in gas sensing applications and IR optical filters. Light impinges perpendicularly onto the sample surface (vertical propagation) so a three-dimensional (3d) structure is used. For gas sensing, a sharp resonance is desired in order to isolate an absorption line of the gas of interest. The high Q-factors needed mandate the use of a plane defect inside the PhC to give rise to a resonant mode inside the bandgap tuned to the gas absorption line. Furthermore to allow gas passage through the device, an open membrane is required. This can affect the mechanical resilience. To improve the strength of the photonic crystal the pores are extended after the ;active; 3d part. The number of modulations, and the extension length have been optimized to obtain the largest Q-factor with reasonable transmitted power. These proposed structures have been experimentally performed, probing an enhancement of almost an order of magnitude in the Q-factor in respect with the basic case. Simulations considering CO2 have been performed showing that the proposed structures are promising as precise optical gas sensors.

  8. Analytical Study of the Effect of the System Geometry on Photon Sensitivity and Depth of Interaction of Positron Emission Mammography

    PubMed Central

    Aguiar, Pablo; Lois, Cristina

    2012-01-01

    Positron emission mammography (PEM) cameras are novel-dedicated PET systems optimized to image the breast. For these cameras it is essential to achieve an optimum trade-off between sensitivity and spatial resolution and therefore the main challenge for the novel cameras is to improve the sensitivity without degrading the spatial resolution. We carry out an analytical study of the effect of the different detector geometries on the photon sensitivity and the angle of incidence of the detected photons which is related to the DOI effect and therefore to the intrinsic spatial resolution. To this end, dual head detectors were compared to box and different polygon-detector configurations. Our results showed that higher sensitivity and uniformity were found for box and polygon-detector configurations compared to dual-head cameras. Thus, the optimal configuration in terms of sensitivity is a PEM scanner based on a polygon of twelve (dodecagon) or more detectors. We have shown that this configuration is clearly superior to dual-head detectors and slightly higher than box, octagon, and hexagon detectors. Nevertheless, DOI effects are increased for this configuration compared to dual head and box scanners and therefore an accurate compensation for this effect is required. PMID:23049553

  9. Analytical study of the effect of the system geometry on photon sensitivity and depth of interaction of positron emission mammography.

    PubMed

    Aguiar, Pablo; Lois, Cristina

    2012-01-01

    Positron emission mammography (PEM) cameras are novel-dedicated PET systems optimized to image the breast. For these cameras it is essential to achieve an optimum trade-off between sensitivity and spatial resolution and therefore the main challenge for the novel cameras is to improve the sensitivity without degrading the spatial resolution. We carry out an analytical study of the effect of the different detector geometries on the photon sensitivity and the angle of incidence of the detected photons which is related to the DOI effect and therefore to the intrinsic spatial resolution. To this end, dual head detectors were compared to box and different polygon-detector configurations. Our results showed that higher sensitivity and uniformity were found for box and polygon-detector configurations compared to dual-head cameras. Thus, the optimal configuration in terms of sensitivity is a PEM scanner based on a polygon of twelve (dodecagon) or more detectors. We have shown that this configuration is clearly superior to dual-head detectors and slightly higher than box, octagon, and hexagon detectors. Nevertheless, DOI effects are increased for this configuration compared to dual head and box scanners and therefore an accurate compensation for this effect is required.

  10. Flat-Band Slow Light in a Photonic Crystal Slab Waveguide by Vertical Geometry Adjustment and Selective Infiltration of Optofluidics

    NASA Astrophysics Data System (ADS)

    Mansouri-Birjandi, Mohammad Ali; Janfaza, Morteza; Tavousi, Alireza

    2017-07-01

    In this paper, a photonic crystal slab waveguide (PhCSW) for slow light applications is presented. To obtain widest possible flat-bands of slow light regions—regions with large group index (n g), and very low group velocity dispersion (GVD)—two core parameters of PhCSW structure are investigated. The design procedure is based on vertical shifting of the first row of the air holes adjacent to the waveguide center and concurrent selective optofluidic infiltration of the second row. The criteria of {{< n_g \\rangle}} ± 10% variations is used for ease of definition and comparison of flat-band regions. By applying various geometry optimizations for the first row, our results suggest that a waveguide core of W 1.09 would provide a reasonable wide flat-band. Furthermore, infiltration of optofluidics in the second row alongside with geometry adjustments of the first row result in flexible control of 10 < n g < 32 and provide flat-band regions with large bandwidth (10 nm < Δλ < 21.5 nm). Also, negligible GVD as low as β 2 = 10-24 (s2/m) is achieved. Numerical simulations are calculated by means of the three-dimensional plane wave expansion method.

  11. Reconstruction of photonic crystal geometries using a reduced basis method for nonlinear outputs

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, Martin; Barth, Carlo; Pomplun, Jan; Burger, Sven; Becker, Christiane; Schmidt, Frank

    2016-03-01

    Maxwell solvers based on the hp-adaptive finite element method allow for accurate geometrical modeling and high numerical accuracy. These features are indispensable for the optimization of optical properties or reconstruction of parameters through inverse processes. High computational complexity prohibits the evaluation of the solution for many parameters. We present a reduced basis method (RBM) for the time-harmonic electromagnetic scattering problem allowing to compute solutions for a parameter configuration orders of magnitude faster. The RBM allows to evaluate linear and nonlinear outputs of interest like Fourier transform or the enhancement of the electromagnetic field in milliseconds. We apply the RBM to compute light-scattering off two dimensional photonic crystal structures made of silicon and reconstruct geometrical parameters.

  12. Spectral features of the Borrmann effect in 1D photonic crystals in the Laue geometry

    NASA Astrophysics Data System (ADS)

    Novikov, V. B.; Mantsyzov, B. I.; Murzina, T. V.

    2017-05-01

    The Borrmann effect is known as an increase of the X-rays transmission of a perfect crystal in the Laue diffraction scheme when the Bragg diffraction condition are satisfied. Following the trend of the transfer of the X-ray phenomena into the optical spectral range, we experimentally observed and studied the optical analogue of the Borrmann effect for the case of one-dimensional photonic crystals (PhC). For the experiments we made the samples of PhCs based on porous fused silica, which reveal periodical modulation of the refractive index and light absorption. We show that in such structures the Borrmann effect reveals itself as increasing transmission when light propagates through a PhC at the Bragg angle of incidence. Pronounced differences of the Borrmann effect are observed for the PhC structures with light losses concentrated in high or low refractive index layers. The spectral features of the effect are analyzed both experimentally and theoretically.

  13. Poster — Thur Eve — 35: The impact of intensity- and energy-modulated photon radiotherapy (XMRT) optimization on a variety of organ geometries

    SciTech Connect

    McGeachy, P.; Villarreal-Barajas, J. E.; Khan, R.; Zinchenko, Y.

    2014-08-15

    We previously reported on a novel, modulated in both energy and intensity; photon radiotherapy (XMRT) optimization technique. The purpose of this investigation was to test this XMRT optimization against conventional intensity modulated radiotherapy (IMRT) optimization on four different organ test geometries. All geometries mimicked clinically relevant scenarios. Both IMRT and XMRT were based on a linear programming approach where the objective function was the mean dose to healthy organs and organ-specific linear dose-point constraints were used. For IMRT, the beam energy was fixed to 6 MV while XMRT optimized in terms of both 6 and 18 MV beams. All plans consisted of a seven beam coplanar arrangement. All organ geometries were contoured on a 25cm diameter cylindrical water phantom in open source radiotherapy research software known as CERR. Solutions for both IMRT and XMRT were obtained for each geometry using a numerical solver Gurobi. Analyzing the quality of the solutions was done by comparing dose distributions and dose volume histograms calculated using CERR. For all four geometries, IMRT and XMRT solutions were comparable in terms of target coverage. For two of the geometries, IMRT provided an advantage in terms of reduced dose to the healthy structures. XMRT showed improved dose reduction to healthy organs for one geometry and a comparable dose distribution to IMRT for the remaining geometry. The inability to exploit the benefits of using multiple energies may be attributed to limited water phantom diameter and having the majority of the organs in close proximity to the transverse axis.

  14. Accelerating Monte Carlo simulations of photon transport in a voxelized geometry using a massively parallel graphics processing unit.

    PubMed

    Badal, Andreu; Badano, Aldo

    2009-11-01

    It is a known fact that Monte Carlo simulations of radiation transport are computationally intensive and may require long computing times. The authors introduce a new paradigm for the acceleration of Monte Carlo simulations: The use of a graphics processing unit (GPU) as the main computing device instead of a central processing unit (CPU). A GPU-based Monte Carlo code that simulates photon transport in a voxelized geometry with the accurate physics models from PENELOPE has been developed using the CUDATM programming model (NVIDIA Corporation, Santa Clara, CA). An outline of the new code and a sample x-ray imaging simulation with an anthropomorphic phantom are presented. A remarkable 27-fold speed up factor was obtained using a GPU compared to a single core CPU. The reported results show that GPUs are currently a good alternative to CPUs for the simulation of radiation transport. Since the performance of GPUs is currently increasing at a faster pace than that of CPUs, the advantages of GPU-based software are likely to be more pronounced in the future.

  15. Ordered arrays of InGaN/GaN dot-in-a-wire nanostructures as single photon emitters

    NASA Astrophysics Data System (ADS)

    Lazić, Snežana; Chernysheva, Ekaterina; Gačević, Žarko; García-Lepetit, Noemi; van der Meulen, Herko P.; Müller, Marcus; Bertram, Frank; Veit, Peter; Christen, Jürgen; Torres-Pardo, Almudena; González Calbet, José M.; Calleja, Enrique; Calleja, José M.

    2015-03-01

    The realization of reliable single photon emitters operating at high temperature and located at predetermined positions still presents a major challenge for the development of solid-state systems for quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays of GaN nanowires containing InGaN nanodisks. The structures were fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates patterned with nanohole masks prepared by colloidal lithography. Low-temperature cathodoluminescence measurements reveal the spatial distribution of light emitted from a single nanowire heterostructure. The emission originating from the topmost part of the InGaN regions covers the blue-to-green spectral range and shows intense and narrow quantum dot-like photoluminescence lines. These lines exhibit an average linear polarization ratio of 92%. Photon correlation measurements show photon antibunching with a g(2)(0) values well below the 0.5 threshold for single photon emission. The antibunching rate increases linearly with the optical excitation power, extrapolating to the exciton decay rate of ~1 ns-1 at vanishing pump power. This value is comparable with the exciton lifetime measured by time-resolved photoluminescence. Fast and efficient single photon emitters with controlled spatial position and strong linear polarization are an important step towards high-speed on-chip quantum information management.

  16. Space-time simulations of photon, lepton, ionization and nucleon trails of TGF ignition in thunderstorm electric field geometries

    NASA Astrophysics Data System (ADS)

    Connell, Paul

    2015-04-01

    The origin of high energy electrons which contribute to the Relativistic Runaway Electron Avalanche of a TGF are not precisely known, or yet observed, though the most obvious source would seem to be the products of cosmic ray showers, or electron avalanches generated in the high electric field near the tips of lightning leaders. With our new TGF simulation software package LEPTRACK we can now easily create any electric field geometry to be expected in stormclouds, any kind of electron source, and are investigating scenarios of TGF ignition, which may or may not be runaway, and in any direction - not just vertical. Vidoes, lightcurves and spectra, presenting the detailed density structure and time evolution of TGF photon, electron, neucleon and ionization trails were presented for the first time at the AGU Fall Meeting in 2014 - showing the complicated effects of changing electric field strength and air density - and the as yet unrecognized importance of the earth magnetic field in trapping electrons and positrons in the upper atmosphere at the magnetic equator - possibly giving rise to the hard tail seen in some TGF spectra observed by AGILE. We will present here an extension of this work to show the dynamics of TGF ignition scenarios of current interest - upward, downward and randomly directed - both from free electrons and from combinations of lightning leader micro-fields producing electron avalanches, which are then input to the macro-fields expected at or above thunderstorm cloudtops. We will show the spatial shape and time evolution of TGF particle structures, along with their optical and gamma ray spectra emitted, and bring to life their essential physics.

  17. Measurement and tuning of the chromatic dispersion of a silicon photonic wire around the half band gap spectral region.

    PubMed

    Leo, François; Dave, Utsav; Keyvaninia, Shahram; Kuyken, Bart; Roelkens, Gunther

    2014-02-01

    We demonstrate the measurement and tuning of second-to-fourth order dispersion of a silicon wire waveguide in a spectral region of low nonlinear losses. Using white light interferometry we extract the chromatic dispersion of our waveguide from 1950 to 2300 nm. Moreover we demonstrate tuning of the zero dispersion wavelength over more than 100 nm, pushing it to longer wavelength by partially underetching the waveguide.

  18. Low-loss amorphous silicon wire waveguide for integrated photonics: effect of fabrication process and the thermal stability.

    PubMed

    Zhu, Shiyang; Lo, G Q; Kwong, D L

    2010-11-22

    Hydrogenated amorphous silicon (a-Si:H) wire waveguides were fabricated by plasma-enhanced chemical vapor deposition and anisotropic dry etching. With the optimized fabrication process, the propagation losses of as low as 3.2 ± 0.2 dB/cm for the TE mode and 2.3 ± 0.1 dB/cm for the TM mode were measured for the 200 nm (height) × 500 nm (width) wire waveguides at 1550 nm using the standard cutback method. The loss becomes larger at shorter wavelength (~4.4 dB/cm for TE and ~5.0 dB/cm for TM at 1520 nm) and smaller at longer wavelength (~1.9 dB/cm for TE and ~1.4 dB/cm for TM at 1620 nm). With the waveguide width shrinking from 500 nm to 300 nm, the TM mode loss keeps almost unchanged whereas the TE mode loss increases, indicating that the predominant loss contributor is the waveguide sidewall roughness, similar to the crystalline silicon waveguides. Although the a-Si:H and the upper cladding SiO2 were both deposited at 400°C, the propagation loss of the fabricated a-Si:H wire waveguides starts to increase upon furnace annealing under atmosphere at a temperature larger than 300°C: ~13-15 dB/cm after 400°C/30 min annealing and >70 dB/cm after 500°C/30 min annealing, which can be attributed to hydrogen out-diffusion. Even higher temperature (i.e., >600°C) annealing leads to the propagation loss approaching to the polycrystalline silicon counterparts (~40-50 dB/cm) due to onset of a-Si:H solid-phase crystallization.

  19. RCPO1 - A Monte Carlo program for solving neutron and photon transport problems in three dimensional geometry with detailed energy description and depletion capability

    SciTech Connect

    Ondis, L.A., II; Tyburski, L.J.; Moskowitz, B.S.

    2000-03-01

    The RCP01 Monte Carlo program is used to analyze many geometries of interest in nuclear design and analysis of light water moderated reactors such as the core in its pressure vessel with complex piping arrangement, fuel storage arrays, shipping and container arrangements, and neutron detector configurations. Written in FORTRAN and in use on a variety of computers, it is capable of estimating steady state neutron or photon reaction rates and neutron multiplication factors. The energy range covered in neutron calculations is that relevant to the fission process and subsequent slowing-down and thermalization, i.e., 20 MeV to 0 eV. The same energy range is covered for photon calculations.

  20. Generation of parabolic similaritons in tapered silicon photonic wires: comparison of pulse dynamics at telecom and mid-infrared wavelengths.

    PubMed

    Lavdas, Spyros; Driscoll, Jeffrey B; Jiang, Hongyi; Grote, Richard R; Osgood, Richard M; Panoiu, Nicolae C

    2013-10-01

    We study the generation of parabolic self-similar optical pulses in tapered Si photonic nanowires (Si-PhNWs) at both telecom (λ=1.55 μm) and mid-infrared (λ=2.2 μm) wavelengths. Our computational study is based on a rigorous theoretical model, which fully describes the influence of linear and nonlinear optical effects on pulse propagation in Si-PhNWs with arbitrarily varying width. Numerical simulations demonstrate that, in the normal dispersion regime, optical pulses evolve naturally into parabolic pulses upon propagation in millimeter-long tapered Si-PhNWs, with the efficiency of this pulse-reshaping process being strongly dependent on the spectral and pulse parameter regime in which the device operates, as well as the particular shape of the Si-PhNWs.

  1. Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector.

    PubMed

    Renema, J J; Wang, Q; Gaudio, R; Komen, I; op 't Hoog, K; Sahin, D; Schilling, A; van Exter, M P; Fiore, A; Engel, A; de Dood, M J A

    2015-07-08

    We probe the local detection efficiency in a nanowire superconducting single-photon detector along the cross-section of the wire with a far subwavelength resolution. We experimentally find a strong variation in the local detection efficiency of the device. We demonstrate that this effect explains previously observed variations in NbN detector efficiency as a function of device geometry.

  2. Reliability of thermal conductivity measurement of liquids by using transient hot-wire, photon-correlation spectroscopy and the laser flash method

    NASA Astrophysics Data System (ADS)

    Kwon, Suyong; Lee, Joohyun; Kim, Dae Ho

    2016-05-01

    Measuring the thermal conductivity of liquids is important, but not easy, because of the complexity of and the natural convection in liquids, and reliable thermal conductivity measurements in liquids under various sample conditions is essential for data accuracy. We have introduced and developed a validation chain for measuring the thermal conductivity of liquids by using three different experimental methods: the transient hot-wire (THW), the photon correlation spectroscopy (PCS) and the laser flash (LF) methods in the temperature range from -30 to 90 °C. We checked the performance of the validation chain developed in this study by measuring the thermal conductivity of liquid toluene. We found good agreement between the thermal conductivity data obtained by using the THW, PCS and LF methods. To demonstrate the use of this validation chain for measurements of thermophysical properties in liquids, we also showed its use in measuring the specific heat of a volatile liquid, toluene which can be extracted from thermal conductivity, thermal diffusivity, and density measurements without any effects of volatilization.

  3. Assessment of the effective dose equivalent for external photon radiation. Volume 1, Calculational results for beam and point source geometries: Final report

    SciTech Connect

    Reece, W.D.; Poston, J.W.; Xu, X.G.

    1993-02-01

    Beginning in January 1994, US nuclear power plants must change the way that they determine the radiation exposure to their workforce. At that time, revisions to Title 10 Part 20 of the Code of Federal Regulations will be in force requiring licensees to evaluate worker radiation exposure using a risk-based methodology termed the ``effective dose equivalent.`` A research project was undertaken to improve upon the conservative method presently used for assessing effective dose equivalent. In this project effective dose equivalent was calculated using a mathematical model of the human body, and tracking photon interactions for a wide variety of radiation source geometries using Monte Carlo computer code simulations. Algorithms were then developed to relate measurements of the photon flux on the surface of the body (as measured by dosimeters) to effective dose equivalent. This report (Volume I of a two-part study) describes: the concept of effective dose equivalent, the evolution of the concept and its incorporation into regulations, the variations in human organ susceptibility to radiation, the mathematical modeling and calculational techniques used, the results of effective dose equivalent calculations for a broad range of photon energiesand radiation source geometries. The study determined that for beam radiation sources the highest effective dose equivalent occurs for beams striking the front of the torso. Beams striking the rear of the torsoproduce the next highest effective dose equivalent, with effective dose equivalent falling significantly as one departs from these two orientations. For point sources, the highest effective dose equivalent occurs when the sources are in contact with the body on the front of the torso. For females the highest effective dose equivalent occurs when the source is on the sternum, for males when it is on the gonads.

  4. ITS version 5.0 :the integrated TIGER series of coupled electron/Photon monte carlo transport codes with CAD geometry.

    SciTech Connect

    Franke, Brian Claude; Kensek, Ronald Patrick; Laub, Thomas William

    2005-09-01

    ITS is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of linear time-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. Our goal has been to simultaneously maximize operational simplicity and physical accuracy. Through a set of preprocessor directives, the user selects one of the many ITS codes. The ease with which the makefile system is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is provided by employing accurate cross sections, sampling distributions, and physical models for describing the production and transport of the electron/photon cascade from 1.0 GeV down to 1.0 keV. The availability of source code permits the more sophisticated user to tailor the codes to specific applications and to extend the capabilities of the codes to more complex applications. Version 5.0, the latest version of ITS, contains (1) improvements to the ITS 3.0 continuous-energy codes, (2) multigroup codes with adjoint transport capabilities, (3) parallel implementations of all ITS codes, (4) a general purpose geometry engine for linking with CAD or other geometry formats, and (5) the Cholla facet geometry library. Moreover, the general user friendliness of the software has been enhanced through increased internal error checking and improved code portability.

  5. Influence of left ventricular geometry on thallium-201 gated single-photon emission tomographic findings in patients with known or suspected coronary artery disease.

    PubMed

    Kurisu, Satoshi; Iwasaki, Toshitaka; Ikenaga, Hiroki; Watanabe, Noriaki; Higaki, Tadanao; Shimonaga, Takashi; Ishibashi, Ken; Mitsuba, Naoya; Dohi, Yoshihiro; Kihara, Yasuki

    2014-02-01

    Recent studies have shown good correlations between echocardiography and Tl-201 gated single-photon emission computed tomography (SPECT) for the assessment of left ventricular volumes and ejection fraction. We assessed how left ventricular geometry affected correlations between these values measured by the 2 methods in patients with known or suspected coronary artery disease. There were 109 patients with normal left ventricular geometry, 20 patients with concentric remodeling, 32 patients with eccentric hypertrophy and 28 patients with concentric hypertrophy. In all 4 groups, there were good correlations between end-diastolic volume (EDV) and end-systolic volume (ESV) values measured by echocardiography and quantitative gated SPECT (QGS). EDV and ESV values measured by QGS were significantly underestimated than those measured by echocardiography except for ESV in eccentric hypertrophy. In all 4 groups, ejection fraction (EF) value measured by echocardiography significantly correlated with that measured by QGS, but Bland-Altman plot showed a proportional error. EF value measured by QGS was likely to be overestimated when EF value increased from the median value, and to be underestimated when EF value decreased from the median value especially in concentric remodeling. Tl-201 gated SPECT is a useful tool for the assessment of left ventricular volumes and function, but it requires methodological considerations according to left ventricular geometry.

  6. Basic Wiring.

    ERIC Educational Resources Information Center

    Kaltwasser, Stan; And Others

    This module is the first in a series of three wiring publications; it serves as the foundation for students enrolled in a wiring program. It is a prerequisite to either "Residential Wiring" or "Commercial and Industrial Wiring." The module contains 16 instructional units that cover the following topics: occupational…

  7. Wire Array Photovoltaics

    NASA Astrophysics Data System (ADS)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  8. Frequency-selective near-field radiative heat transfer between photonic crystal slabs: a computational approach for arbitrary geometries and materials.

    PubMed

    Rodriguez, Alejandro W; Ilic, Ognjen; Bermel, Peter; Celanovic, Ivan; Joannopoulos, John D; Soljačić, Marin; Johnson, Steven G

    2011-09-09

    We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic-crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab-slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the nonsymmorphic symmetry group.

  9. Photocatalytic degradation of water contaminants in multiple photoreactors and evaluation of reaction kinetic constants independent of photon absorption, irradiance, reactor geometry, and hydrodynamics.

    PubMed

    Grčić, Ivana; Li Puma, Gianluca

    2013-12-03

    The literature on photocatalytic oxidation of water pollutants often reports reaction kinetic constants, which cannot be unraveled from photoreactor type and experimental conditions. This study addresses this challenging aspect by presenting a general and simple methodology for the evaluation of fundamental "intrinsic" reaction kinetic constants of photocatalytic degradation of water contaminants, which are independent of photoreactor type, catalyst concentration, irradiance levels, and hydrodynamics. The degradation of the model contaminant, oxalic acid (OA) on titanium dioxide (TiO2) aqueous suspensions, was monitored in two annular photoreactors (PR1 and PR2). The photoreactors with significantly different geometries were operated under different hydrodynamic regimes (turbulent batch mode and laminar flow-through recirculation mode), optical thicknesses, catalyst and OA concentrations, and photon irradiances. The local volumetric rate of photon absorption (LVRPA) was evaluated by the six-flux radiation absorption-scattering model (SFM). The SFM was further combined with a comprehensive kinetic model for the adsorption and photodecomposition of OA on TiO2 to determine local reaction rates and, after integration over the reactor volume, the intrinsic reaction kinetic constants. The model could determine the oxidation of OA in both PR1 and PR2 under a wide range of experimental conditions. This study demonstrates a more meaningful way for determining reaction kinetic constants of photocatalytic degradation of water contaminants.

  10. Effects of geometry and linearly polarized cavity photons on charge and spin currents in a quantum ring with spin-orbit interactions

    NASA Astrophysics Data System (ADS)

    Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2014-05-01

    We calculate the persistent charge and spin polarization current inside a finite-width quantum ring of realistic geometry as a function of the strength of the Rashba or Dresselhaus spin-orbit interaction. The time evolution in the transient regime of the two-dimensional (2D) quantum ring connected to electrically biased semi-infinite leads is governed by a time-convolutionless non-Markovian generalized master equation. The electrons are correlated via Coulomb interaction. In addition, the ring is embedded in a photon cavity with a single mode of linearly polarized photon field, which is polarized either perpendicular or parallel to the charge transport direction. To analyze carefully the physical effects, we compare to the analytical results of the toy model of a one-dimensional (1D) ring of non-interacting electrons with spin-orbit coupling. We find a pronounced charge current dip associated with many-electron level crossings at the Aharonov-Casher phase ΔΦ = π, which can be disguised by linearly polarized light. Qualitative agreement is found for the spin polarization currents of the 1D and 2D ring. Quantitatively, however, the spin polarization currents are weaker in the more realistic 2D ring, especially for weak spin-orbit interaction, but can be considerably enhanced with the aid of a linearly polarized electromagnetic field. Specific spin polarization current symmetries relating the Dresselhaus spin-orbit interaction case to the Rashba one are found to hold for the 2D ring, which is embedded in the photon cavity.

  11. Magnetism in curved geometries

    DOE PAGES

    Streubel, Robert; Fischer, Peter; Kronast, Florian; ...

    2016-08-17

    Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii–Moriya-like interaction. Asmore » a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. Finally, these recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.« less

  12. Magnetism in curved geometries

    SciTech Connect

    Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys

    2016-08-17

    Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii–Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. Finally, these recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

  13. Magnetism in curved geometries

    NASA Astrophysics Data System (ADS)

    Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys

    2016-09-01

    Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

  14. Wire stripper

    NASA Technical Reports Server (NTRS)

    Economu, M. A. (Inventor)

    1978-01-01

    An insulation stripper is described which is especially useful for shielded wire, the stripper including a first pair of jaws with blades extending substantially perpendicular to the axis of the wire, and a second pair of jaws with blades extending substantially parallel to the axis of the wire. The first pair of jaws is pressed against the wire so the blades cut into the insulation, and the device is turned to form circumferential cuts in the insulation. Then the second pair of jaws is pressed against the wire so the blades cut into the insulation, and the wire is moved through the device to form longitudinal cuts that permit easy removal of the insulation. Each of the blades is located within the concave face of a V-block, to center the blades on the wire and to limit the depth of blade penetration.

  15. Photons with Momentum Along Curved Paths

    NASA Astrophysics Data System (ADS)

    Davis, Basil S.

    Electromagnetic energy flow is expressed mathematically by the Poynting Vector. Quantum theory determines that the Poynting Vector provides the direction of movement of the photons which are the quanta of the electromagnetic field. In this dissertation important phenomena featuring the flow of electromagnetic energy—and hence transport of photons—along curved paths are investigated. A circuit is considered in the shape of a ring, with a battery of negligible size and a wire of uniform resistance. A linear charge distribution in the wire generates an electrostatic field and a steady current through the circuit which maintains a constant magnetic field. Earlier studies of the Poynting vector and the rate of flow of energy considered only idealized geometries in which the Poynting vector was confined to the space within the circuit. But in more realistic cases the Poynting vector is nonzero outside as well as inside the circuit. An expression is obtained for the Poynting vector in terms of products of integrals, which are evaluated numerically to show the energy flow. Limiting expressions are obtained analytically. It is shown that the total power generated by the battery equals the energy flowing into the wire per unit time. Whereas the Poynting Vector flows along the direction of propagation of a plane wave photon, it is a different matter with photons described by Laguerre-Gaussian transverse profiles. Such "twisted" photon beams have a spiraling Poynting Vector that generates an orbital angular momentum that is distinct from the photon's spin angular momentum. The transverse confinement of the twisted photon beam gives rise to a Gouy phase shift, and the transverse structure of this phase shift is characterized by the Gouy radius. A new expression is obtained for this radius in terms of the parameters w, p, and ℓ of the Laguerre-Gaussian beam profile. The orbital angular momentum states have a two-fold degeneracy with respect to the winding

  16. Study of a selection of 10 historical types of dosemeter: variation of the response to Hp(10) with photon energy and geometry of exposure.

    PubMed

    Thierry-Chef, I; Pernicka, F; Marshall, M; Cardis, E; Andreo, P

    2002-01-01

    An international collaborative study of cancer risk among workers in the nuclear industry is tinder way to estimate direetly the cancer risk following protracted low-dose exposure to ionising radiation. An essential aspect of this study is the characterisation and quantification of errors in available dose estimates. One major source of errors is dosemeter response in workplace exposure conditions. Little information is available on energy and geometry response for most of the 124 different dosemeters used historically in participating facilities. Experiments were therefore set up to assess this. using 10 dosemeter types representative of those used over time. Results show that the largest errors were associated with the response of early dosemeters to low-energy photon radiation. Good response was found with modern dosemeters. even at low energy. These results are being used to estimate errors in the response for each dosemeter type, used in the participating facilities, so that these can be taken into account in the estimates of cancer risk.

  17. Diagnostics for exploding wires (abstract)

    NASA Astrophysics Data System (ADS)

    Moosman, B.; Bystritskii, Vitaly; Wessel, F. J.; Van Drie, A.

    1999-01-01

    Two diagnostics, capable of imaging fast, high temperature, plasmas were used on exploding wire experiments at UC Irvine. An atmospheric pressure nitrogen laser (λ=337.1 nm) was used to generate simultaneous shadow and shearing interferogram images with a temporal resolution of ˜1 ns and a spatial resolution of 10 μm. An x-ray backlighter imaged the exploding wire 90° with respect to the laser and at approximately the same instant in time. The backlighter spatial resolution as determined by geometry and film resolution was 25 μm. Copper wires of diameters (25, 50, and 100 μm) and steel wire d=25 μm were exploded in vacuum (10-5 Torr) at a maximum current level of 12 kA, by a rectified marx bank at a voltage of 50 kV and a current rise time (quarter period) of 900 ns. Copper wires which were cleaned and then resistively heated under vacuum to incandescence for several hours prior to high current initiation, exhibited greater expansion velocities at peak current than wires which had not been heated prior to discharge. Axial variations on the surface of the wire observed with the laser were found to correlate with bulk axial mass differences from x-ray backlighting. High electron density, measured near the opaque surface of the exploding wire, suggests that much of the current is shunted outward away from the bulk of the wire.

  18. Positioning and joining of organic single-crystalline wires.

    PubMed

    Wu, Yuchen; Feng, Jiangang; Jiang, Xiangyu; Zhang, Zhen; Wang, Xuedong; Su, Bin; Jiang, Lei

    2015-03-27

    Organic single-crystal, one-dimensional materials can effectively carry charges and/or excitons due to their highly ordered molecule packing, minimized defects and eliminated grain boundaries. Controlling the alignment/position of organic single-crystal one-dimensional architectures would allow on-demand photon/electron transport, which is a prerequisite in waveguides and other optoelectronic applications. Here we report a guided physical vapour transport technique to control the growth, alignment and positioning of organic single-crystal wires with the guidance of pillar-structured substrates. Submicrometre-wide, hundreds of micrometres long, highly aligned, organic single-crystal wire arrays are generated. Furthermore, these organic single-crystal wires can be joined within controlled angles by varying the pillar geometries. Owing to the controllable growth of organic single-crystal one-dimensional architectures, we can present proof-of-principle demonstrations utilizing joined wires to allow optical waveguide through small radii of curvature (internal angles of ~90-120°). Our methodology may open a route to control the growth of organic single-crystal one-dimensional materials with potential applications in optoelectronics.

  19. Positioning and joining of organic single-crystalline wires

    PubMed Central

    Wu, Yuchen; Feng, Jiangang; Jiang, Xiangyu; Zhang, Zhen; Wang, Xuedong; Su, Bin; Jiang, Lei

    2015-01-01

    Organic single-crystal, one-dimensional materials can effectively carry charges and/or excitons due to their highly ordered molecule packing, minimized defects and eliminated grain boundaries. Controlling the alignment/position of organic single-crystal one-dimensional architectures would allow on-demand photon/electron transport, which is a prerequisite in waveguides and other optoelectronic applications. Here we report a guided physical vapour transport technique to control the growth, alignment and positioning of organic single-crystal wires with the guidance of pillar-structured substrates. Submicrometre-wide, hundreds of micrometres long, highly aligned, organic single-crystal wire arrays are generated. Furthermore, these organic single-crystal wires can be joined within controlled angles by varying the pillar geometries. Owing to the controllable growth of organic single-crystal one-dimensional architectures, we can present proof-of-principle demonstrations utilizing joined wires to allow optical waveguide through small radii of curvature (internal angles of ~90–120°). Our methodology may open a route to control the growth of organic single-crystal one-dimensional materials with potential applications in optoelectronics. PMID:25814032

  20. Wire chamber

    DOEpatents

    Atac, Muzaffer

    1989-01-01

    A wire chamber or proportional counter device, such as Geiger-Mueller tube or drift chamber, improved with a gas mixture providing a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor.

  1. Residential Wiring.

    ERIC Educational Resources Information Center

    Taylor, Mark

    The second in a series of three curriculum packages on wiring, these materials for a five-unit course were developed to prepare postsecondary students for entry-level employment in the residential wiring trade. The five units are: (1) blueprint reading and load calculations; (2) rough-in; (3) service; (4) trim out and troubleshooting; and (5) load…

  2. Wire rope research and logging. [Skyline and dragline systems

    SciTech Connect

    Morgenstern, M.H.

    1981-01-01

    The various factors affecting the service life of wire ropes in skyline and dragline systems are discussed: design, geometry, sheave geometry, wear and lubrication, sheave hardness, pickup of small rocks, etc. (DLC)

  3. Wire Wise.

    ERIC Educational Resources Information Center

    Swanquist, Barry

    1998-01-01

    Discusses how today's technology is encouraging schools to invest in furnishings that are adaptable to computer use and telecommunications access. Explores issues concerning modularity, wiring management, ergonomics, durability, price, and aesthetics. (GR)

  4. Wire Wise.

    ERIC Educational Resources Information Center

    Swanquist, Barry

    1998-01-01

    Discusses how today's technology is encouraging schools to invest in furnishings that are adaptable to computer use and telecommunications access. Explores issues concerning modularity, wiring management, ergonomics, durability, price, and aesthetics. (GR)

  5. Neural wiring optimization.

    PubMed

    Cherniak, Christopher

    2012-01-01

    Combinatorial network optimization theory concerns minimization of connection costs among interconnected components in systems such as electronic circuits. As an organization principle, similar wiring minimization can be observed at various levels of nervous systems, invertebrate and vertebrate, including primate, from placement of the entire brain in the body down to the subcellular level of neuron arbor geometry. In some cases, the minimization appears either perfect, or as good as can be detected with current methods. One question such best-of-all-possible-brains results raise is, what is the map of such optimization, does it have a distinct neural domain?

  6. No Wires.

    ERIC Educational Resources Information Center

    DeLoughry, Thomas J.

    1995-01-01

    The University of California at Santa Cruz has completed a successful test of a wireless computer network that would enable students and professors to get on line from anywhere on campus. The network, linked by radio waves, could save millions of dollars in campus wiring costs and would better meet student and faculty information needs. (MSE)

  7. No Wires.

    ERIC Educational Resources Information Center

    DeLoughry, Thomas J.

    1995-01-01

    The University of California at Santa Cruz has completed a successful test of a wireless computer network that would enable students and professors to get on line from anywhere on campus. The network, linked by radio waves, could save millions of dollars in campus wiring costs and would better meet student and faculty information needs. (MSE)

  8. Design of NbN Superconducting Nanowire Single-Photon Detectors with Enhanced Infrared Detection Efficiency

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Renema, J. J.; Engel, A.; de Dood, M. J. A.

    2017-09-01

    We optimize the design of NbN nanowire superconducting single-photon detectors using the recently discovered position-dependent detection efficiency in these devices. This optimized design of meandering wire NbN detectors maximizes absorption at positions where photon detection is most efficient by altering the field distribution across the wire. In order to calculate the response of the detectors with different geometries, we use a monotonic local detection efficiency from a nanowire and optical absorption distribution via finite-difference-time-domain simulations. The calculations predict a trade-off between average absorption and absorption at the edge, leading to a predicted optimal wire width close to 100 nm for a 1550-nm wavelength, which drops to a 50-nm wire width for a 600-nm wavelength. The absorption at the edges can be enhanced by depositing a silicon nanowire on top of the superconducting nanowire, which improves both the total absorption efficiency and the internal detection efficiency of meandering wire structures. The proposed structure can be integrated in a relatively simple cavity structure to reach absorption efficiencies of 97% for perpendicular and 85% for parallel polarization.

  9. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, Eldon D.; Hooper, Frederick M.; Reichenbach, Marvin L.

    1992-01-01

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

  10. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

    1992-08-11

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

  11. Photon detectors

    SciTech Connect

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  12. Unwinding of a single quantized vortex from a wire

    SciTech Connect

    Schwarz, K.W. )

    1993-05-01

    The dynamical behavior of a quantized vortex partially attached to a wire is studied theoretically, with the aim of interpreting recent experiments on quantized circulation in superfluid [sup 3]He-B. The geometry considered consists of a thin wire running parallel to the axis of a circular cylinder enclosing the wire. The circulation is assumed to run part way up the wire, and then to enter the fluid as a free vortex which eventually terminates on the outer wall. It is found that such a vortex achieves a state of steady precession around the wire, accompanied by a steady unwinding motion down the wire due to frictional effects. For an off-center wire, both the precession rate and the unwinding rate develop oscillatory components. Various particulars, such as the effects of friction, of moving the wire off center, and of pinning, are investigated. Excellent agreement is obtained between experiment, analytical theory, and numerical calculations.

  13. Wire Retrieves Broken Pin

    NASA Technical Reports Server (NTRS)

    Burow, G. H.

    1984-01-01

    Safety wire retains pieces of broken tool. Retrieval wire running through shaft of tool used to pull pieces of tool out of hole, should tool break during use. Safety wire concept suitable for pins subject to deflection or breakage.

  14. Automated wire preparation system

    NASA Astrophysics Data System (ADS)

    McCulley, Deborah J.

    The first step toward an automated wire harness facility for the aerospace industry has been taken by implementing the Wire Vektor 2000 into the wire harness preparation area. An overview of the Wire Vektor 2000 is given, including the facilities for wire cutting, marking, and transporting, for wire end processing, and for system control. Production integration in the Wire Vektor 2000 system is addressed, considering the hardware/software debug system and the system throughput. The manufacturing changes that have to be made in implementing the Wire Vektor 2000 are discussed.

  15. Motion control of the accumulator flying wires

    SciTech Connect

    Wang, X.Q.

    1990-04-23

    Flying wire systems for the Fermilab Accumulator are being constructed in order to measure the transverse beam profiles during stacking. Each device passes a 25 micron carbon filament through the beam transversely at a constant velocity of 10 m/s. Collisions between the beam particles and the wire produce secondary particle cascades, which in turn produce photons in a scintillator. A photomultiplier tube is used to measure the light intensity while the wire position is determined by an optical encoder. There are six Accumulator flying wire systems. Four of them are to be used in normal stacking operation: two horizontal and two vertical flying wires are in the AP40 high dispersion section, covering the core orbit and the extraction orbit respectively. The other two horizontal wires are for measuring the momentum distribution of the beam on the central orbit at the Accumulator transition energy. At the AP40 high dispersion region a wire covers the central orbit, the other is in the AP30 low dispersion section. The operation and control of the flying wire system is discussed in this paper. 11 figs.

  16. Comparison of conversion coefficients for equivalent dose in terms of air kerma using a sitting and standing female adult voxel simulators exposure to photons in antero-posterior irradiation geometry

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. R.; Galeano, D. C.; Carvalho Júnior, A. B.; Hunt, J.

    2014-02-01

    Due to the difficulty in implementing invasive techniques for calculations of dose for some exposure scenarios, computational simulators have been created to represent as realistically as possible the structures of the human body and through radiation transport simulations to obtain conversion coefficients (CCs) to estimate dose. In most published papers simulators are implemented in the standing posture and this may not describe a real scenario of exposure. In this work we developed exposure scenarios in the Visual Monte Carlo (VMC) code using a female simulator in standing and sitting postures. The simulator was irradiated in the antero-posterior (AP) geometry by a plane source of monoenergetic photons with energy from 10 keV to 2 MeV. The conversion coefficients for equivalent dose in terms of air kerma (HT/Kair) were calculated for both scenarios and compared. The results show that the percentage difference of CCs for the organs of the head and thorax was not significant (less than 5%) since the anatomic position of the organs is the same in both postures. The percentage difference is more significant to the ovaries (71% for photon energy of 20 keV), to the bladder (39% at 60 keV) and to the uterus (37% at 100 keV) due to different processes of radiation interactions in the legs of the simulator when its posture is changed. For organs and tissues that are distributed throughout the entire body, such as bone (21% at 100 keV) and muscle (30% at 80 keV) the percentage difference of CCs reflects a reduction of interaction of photons with the legs of the simulator. Therefore, the calculation of conversion coefficients using simulators in the sitting posture is relevant for a more accurate dose estimation in real exposures to radiation.

  17. Study on the measurement of photo-neutron for15 MV photon beam from medical linear accelerator under different irradiation geometries using passive detectors.

    PubMed

    Thekkedath, Siji Cyriac; Raman, R Ganapathi; Musthafa, M M; Bakshi, A K; Pal, Rupali; Dawn, Sandipan; Kummali, Abdul Haneefa; Huilgol, Nagraj G; Selvam, T Palani; Datta, D

    2016-01-01

    The photo-neutron dose equivalents of 15 MV Elekta precise accelerators were measured for different depths in phantom, for various field sizes, at different distances from the isocenter in the patient plane and for various wedged fields. Fast and thermal neutrons are measured using passive detectors such as Columbia Resin-39 and pair of thermoluminescent dosimetry (TLD) 600 and TLD 700 detector from Elekta medical linear accelerator. It is found that fast photo-neutron dose rate decreases as the depth increases, with a maximum of 0.57 ± 0.08 mSv/Gy photon dose at surface and minimum of 0.09 ± 0.02 mSv/Gy photon dose at 15 cm depth of water equivalent phantom with 10 cm backscatter. Photo neutrons decreases from 1.28 ± 0.03 mSv/Gy to 0.063 ± 0.032 when measured at isocenter and at 100 cm far from the field edge along the longitudinal direction in the patient plane. Fast and thermal neutron doses increases from 0.65 ± 0.05 mSv/Gy to 1.08 ± 0.07 mSv/Gy as the field size increases; from 5 cm × 5 cm to 30 cm × 30 cm for fast neutrons. With increase in wedge field angle from 0° to 60°, it is observed that the fast neutron dose increases from 0.42 ± 0.03 mSv/Gy to 0.95 ± 0.05 mSv/Gy.s Measurements indicate the photo-neutrons at few field sizes are slightly higher than the International Electrotechnical Commission standard specifications. Photo-neutrons from Omni wedged fields are studied in details. These studies of the photo-neutron energy response will enlighten the neutron dose to radiation therapy patients and are expected to further improve radiation protection guidelines.

  18. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. Trolley wires, trolley feeder wires, and bare signal wires shall be insulated...

  19. Windows: Life after Wire.

    ERIC Educational Resources Information Center

    Razwick, Jerry

    2003-01-01

    Although wired glass is extremely common in school buildings, the International Building Code adopted new standards that eliminate the use of traditional wired glass in K-12 schools, daycare centers, and athletic facilities. Wired glass breaks easily, and the wires can cause significant injuries by forming dangerous snags when the glass breaks.…

  20. Windows: Life after Wire.

    ERIC Educational Resources Information Center

    Razwick, Jerry

    2003-01-01

    Although wired glass is extremely common in school buildings, the International Building Code adopted new standards that eliminate the use of traditional wired glass in K-12 schools, daycare centers, and athletic facilities. Wired glass breaks easily, and the wires can cause significant injuries by forming dangerous snags when the glass breaks.…

  1. Photovoltaic response in a resonant tunneling wire-dot-wire junction

    NASA Astrophysics Data System (ADS)

    Berbezier, Aude; Autran, Jean-Luc; Michelini, Fabienne

    2013-07-01

    Using the Green's function technique, we investigated the nonequilibrium photovoltaic response in a double barrier wire-dot-wire junction for tunneling coupling stronger than optical coupling. In the narrow window of photon-gap energy resonance, the photocurrent increases when the voltage increases from zero, which means a negative shunt conductance in the generator equivalent circuit, and forces a fill factor above one. We then show a counterintuitive behavior of such resonant tunneling photovoltaic systems: the photocurrent increases when the tunneling rate through contact decreases. The negative shunt conductance we observed hence rises in the density of states of semi-infinite wires that vanishes at band edges.

  2. Stretched Wire Mechanics

    SciTech Connect

    Bowden, Gordon; /SLAC

    2005-09-06

    Stretched wires are beginning to play an important role in the alignment of accelerators and synchrotron light sources. Stretched wires are proposed for the alignment of the 130 meter long LCLS undulator. Wire position technology has reached sub-micron resolution yet analyses of perturbations to wire straightness are hard to find. This paper considers possible deviations of stretched wire from the simple 2-dimensional catenary form.

  3. Thermal conductivity modeling of circular-wire nanocomposites

    NASA Astrophysics Data System (ADS)

    Hsieh, Tse-Yang; Yang, Jaw-Yen

    2010-08-01

    A phonon Boltzmann equation solver using multiblock-structured grid system is developed and applied to study transverse thermal transport in silicon-germanium circular-wire nanocomposite (silicon nanowires embedded in germanium host matrix). Past studies usually assume geometric simplification for the circular-wire nanocomposite, so the heat transfer is actually modeled in a square-wire nanocomposite. To demonstrate geometry effect, phonon transport in both the circular-wire and square-wire nanocomposites are investigated with various wire spacings, volume fractions, and dimensions. In ballistic phonon transport, due to the smoothness of circular shape, the circular wire imposes less thermal resistance than the square wire. Nevertheless, in the geometric simplification, the wire spacing of the square-wire nanocomposite is larger than that of the circular-wire nanocomposite. The usual geometric simplification can overestimate the thermal conductivity of the circular-wire nanocomposite. The obtained results can provide essential information for the development of bulk-nanostructured thermoelectric devices.

  4. Photon track evolution.

    PubMed

    Oliveira, A D

    2005-01-01

    Given the time scale of biological, biochemical, biophysical and physical effects in a radiation exposure of living tissue, the first physical stage can be considered to be independent of time. All the physical interactions caused by the incident photons happen at the same starting time. From this point of view it would seem that the evolution of photon tracks is not a relevant topic for analysis; however, if the photon track is considered as a sequence of several interactions, there are several steps until the total degradation of the energy of the primary photon. We can characterise the photon track structure by the probability p(E,j), that is, the probability that a photon with energy E suffers j secondary interactions. The aim of this work is to analyse the photon track structure by considering j as a step of the photon track evolution towards the total degradation of the photon energy. Low energy photons (<150 keV) are considered, with water phantoms and half-extended geometry. The photon track evolution concept is presented and compared with the energy deposition along the track and also with the spatial distribution of the several steps in the photon track.

  5. Power and Energy of Exploding Wires

    NASA Astrophysics Data System (ADS)

    Valancius, Cole

    2015-06-01

    Exploding wires are used in many high-energy applications, such as initiating explosives. Analysis of gold wire burst in detonator applications has shown Burst Current and Action metrics to be incapable of explaining burst phenomenon as the inductance of a firing circuit is changed. Energy Density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in Power-Energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a more broad understanding of rapid metal phase transition and the physical applications of the released shock wave.

  6. Power and energy of exploding wires

    NASA Astrophysics Data System (ADS)

    Valancius, Cole J.; Garasi, Christopher J.; O'Malley, Patrick D.

    2017-01-01

    Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a more broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.

  7. Wire chambers revisited.

    PubMed

    Ott, R J

    1993-04-01

    Detectors used for radioisotope imaging have, historically, been based on scintillating crystal/photomultiplier combinations in various forms. From the rectilinear scanner through to modern gamma cameras and positron cameras, the basic technology has remained much the same. Efforts to overcome the limitations of this form of technology have foundered on the inability to reproduce the required sensitivity, spatial resolution and sensitive area at acceptable cost. Multiwire proportional chambers (MWPCs) have long been used as position-sensitive charged particle detectors in nuclear and high-energy physics. MWPCs are large-area gas-filled ionisation chambers in which large arrays of fine wires are used to measure the position of ionisation produced in the gas by the passage of charged particles. The important properties of MWPCs are high-spatial-resolution, large-area, high-count-rate performance at low cost. For research applications, detectors several metres square have been built and small-area detectors have a charged particle resolution of 0.4 mm at a count rate of several million per second. Modification is required to MWPCs for nuclear medicine imaging. As gamma rays or X-rays cannot be detected directly, they must be converted into photo- or Compton scatter electrons. Photon-electron conversion requires the use of high atomic number materials in the body of the chamber. Pressurised xenon is the most useful form of "gas only" photon-electron convertor and has been used successfully in a gamma camera for the detection of gamma rays at energies below 100 keV. This camera has been developed specifically for high-count-rate first-pass cardiac imaging. This high-pressure xenon gas MWPC is the key to a highly competitive system which can outperform scintillator-based systems. The count rate performance is close to a million counts per second and the intrinsic spatial resolution is better than the best scintillator-based camera. The MWPC camera produces quantitative

  8. Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

    NASA Astrophysics Data System (ADS)

    Galeano, D. C.; Cavalcante, F. R.; Carvalho, A. B.; Hunt, J.

    2014-02-01

    The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature.

  9. Concealed wire tracing apparatus

    DOEpatents

    Kronberg, James W.

    1994-01-01

    An apparatus and method that combines a signal generator and a passive signal receiver to detect and record the path of partially or completely concealed electrical wiring without disturbing the concealing surface. The signal generator applies a series of electrical pulses to the selected wiring of interest. The applied pulses create a magnetic field about the wiring that can be detected by a coil contained within the signal receiver. An audible output connected to the receiver and driven by the coil reflects the receivers position with respect to the wiring. The receivers audible signal is strongest when the receiver is directly above the wiring and the long axis of the receivers coil is parallel to the wiring. A marking means is mounted on the receiver to mark the location of the wiring as the receiver is directed over the wiring's concealing surface. Numerous marks made on various locations of the concealing surface will trace the path of the wiring of interest.

  10. Wire Test Grip Fixture

    NASA Technical Reports Server (NTRS)

    Burke, Christopher S.

    2011-01-01

    Wire-testing issues, such as the gripping strains imposed on the wire, play a critical role in obtaining clean data. In a standard test frame fitted with flat wedge grips, the gripping action alone creates stresses on the wire specimen that cause the wire to fail at the grip location. A new test frame, which is outfitted with a vacuum chamber, negated the use of any conventional commercially available wire test fixtures, as only 7 in. (17.8 cm) existed between the grip faces. An innovative grip fixture was designed to test thin gauge wire for a variety of applications in an existing Instron test frame outfitted with a vacuum chamber.

  11. Subtracted geometry

    NASA Astrophysics Data System (ADS)

    Saleem, Zain Hamid

    In this thesis we study a special class of black hole geometries called subtracted geometries. Subtracted geometry black holes are obtained when one omits certain terms from the warp factor of the metric of general charged rotating black holes. The omission of these terms allows one to write the wave equation of the black hole in a completely separable way and one can explicitly see that the wave equation of a massless scalar field in this slightly altered background of a general multi-charged rotating black hole acquires an SL(2, R) x SL(2, R) x SO(3) symmetry. The "subtracted limit" is considered an appropriate limit for studying the internal structure of the non-subtracted black holes because new 'subtracted' black holes have the same horizon area and periodicity of the angular and time coordinates in the near horizon regions as the original black hole geometry it was constructed from. The new geometry is asymptotically conical and is physically similar to that of a black hole in an asymptotically confining box. We use the different nice properties of these geometries to understand various classically and quantum mechanically important features of general charged rotating black holes.

  12. Base Information Transport Infrastructure Wired (BITI Wired)

    DTIC Science & Technology

    2016-03-01

    2016 Major Automated Information System Annual Report Base Information Transport Infrastructure Wired (BITI Wired) Defense Acquisition Management ...Major Automated Information System MAIS OE - MAIS Original Estimate MAR – MAIS Annual Report MDA - Milestone Decision Authority MDD - Materiel...Combat Information Transport System program was restructured into two pre-Major Automated Information System (pre-MAIS) components: Information

  13. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1999-01-01

    The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 degree C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: (1) 3.7 amps per wire (2) bundle of 15 or more wires (3) 70 C environment (4) vacuum of 10(exp -5) torr or less To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

  14. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1998-01-01

    The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: 3.7 amps per wire, bundle of 15 or more wires, 70 C environment, and vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

  15. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1998-01-01

    The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: (1) 3.7 amps per wire; (2) bundle of 15 or more wires; (3) 70 C environment: and (4) vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

  16. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1998-01-01

    The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: 3.7 amps per wire, bundle of 15 or more wires, 70 C environment, and vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

  17. Wire harness twisting aid

    NASA Technical Reports Server (NTRS)

    Casey, E. J.; Commadore, C. C.; Ingles, M. E.

    1980-01-01

    Long wire bundles twist into uniform spiral harnesses with help of simple apparatus. Wires pass through spacers and through hand-held tool with hole for each wire. Ends are attached to low speed bench motor. As motor turns, operator moves hand tool away forming smooth twists in wires between motor and tool. Technique produces harnesses that generate less radio-frequency interference than do irregularly twisted cables.

  18. Wire harness twisting aid

    NASA Technical Reports Server (NTRS)

    Casey, E. J.; Commadore, C. C.; Ingles, M. E.

    1980-01-01

    Long wire bundles twist into uniform spiral harnesses with help of simple apparatus. Wires pass through spacers and through hand-held tool with hole for each wire. Ends are attached to low speed bench motor. As motor turns, operator moves hand tool away forming smooth twists in wires between motor and tool. Technique produces harnesses that generate less radio-frequency interference than do irregularly twisted cables.

  19. Laser Wire Stripper

    NASA Technical Reports Server (NTRS)

    1983-01-01

    NASA-developed space shuttle technology is used in a laser wire stripper designed by Raytheon Company. Laser beams cut through insulation on a wire without damaging conductive metal, because laser radiation that melts plastic insulation is reflected by the metal. The laser process is fast, clean, precise and repeatable. It eliminates quality control problems and the expense of rejected wiring.

  20. EMF wire code research

    SciTech Connect

    Jones, T.

    1993-11-01

    This paper examines the results of previous wire code research to determines the relationship with childhood cancer, wire codes and electromagnetic fields. The paper suggests that, in the original Savitz study, biases toward producing a false positive association between high wire codes and childhood cancer were created by the selection procedure.

  1. Flicking-wire drag tensioner

    NASA Technical Reports Server (NTRS)

    Dassele, M. A.; Fairall, H.

    1978-01-01

    Wire-drag system improves wire profile and applies consistent drag to wire. Wire drag is continuously adjustable from zero drag to tensile strength of wire. No-sag wire drag is easier to thread than former system and requires minimal downtime for cleaning and maintenance.

  2. Nonlinear silicon photonics

    NASA Astrophysics Data System (ADS)

    Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

    2017-09-01

    Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

  3. Do K-wires made from shape memory alloys increase pull-out forces? A preliminary experimental cadaver study in bovine bone.

    PubMed

    Wiebking, U; Gösling, T; Monschizada, W; Rau, T; Krettek, C

    2007-06-01

    After osteosynthesis of the proximal humerus by Kirschner wires (K-wire), loosening and secondary loss can occur. This study tested primary fixation of wires made from a shape memory alloy (SMA) Nitinol (NiTi), compared to conventional steel K-wires by pull-out tests. Blocks of cancellous bone were tested with three wire types: NiTi-K-wire with split apex geometry and conventional steel K-wires with and without threads. We found that NiTi-wires can be pulled out of bone more easily than steel wires (P=0.05), even though the former had rougher surfaces. The application of NiTi-wires through bone produced no better stability in comparison to normal steel K-wires, because of triggering the memory effect. Further studies are required to determine if NiTi wires of another appropriate design, surface and localization are superior to conventional wires in the context of this application.

  4. Induced Voltage in an Open Wire

    NASA Astrophysics Data System (ADS)

    Morawetz, K.; Gilbert, M.; Trupp, A.

    2017-07-01

    A puzzle arising from Faraday's law has been considered and solved concerning the question which voltage will be induced in an open wire with a time-varying homogeneous magnetic field. In contrast to closed wires where the voltage is determined by the time variance of the magnetic field and the enclosed area, in an open wire we have to integrate the electric field along the wire. It is found that the longitudinal electric field with respect to the wave vector contributes with 1/3 and the transverse field with 2/3 to the induced voltage. In order to find the electric fields the sources of the magnetic fields are necessary to know. The representation of a spatially homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or symmetry line which depend on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to this symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire placed with different angles in the magnetic field. We present exactly solvable models of the Maxwell equations for a symmetry point and for a symmetry line, respectively. The results are applicable to open circuit problems like corrosion and for astrophysical applications.

  5. Molecular Geometry.

    ERIC Educational Resources Information Center

    Desseyn, H. O.; And Others

    1985-01-01

    Compares linear-nonlinear and planar-nonplanar geometry through the valence-shell electron pairs repulsion (V.S.E.P.R.), Mulliken-Walsh, and electrostatic force theories. Indicates that although the V.S.E.P.R. theory has more advantages for elementary courses, an explanation of the best features of the different theories offers students a better…

  6. Molecular Geometry.

    ERIC Educational Resources Information Center

    Desseyn, H. O.; And Others

    1985-01-01

    Compares linear-nonlinear and planar-nonplanar geometry through the valence-shell electron pairs repulsion (V.S.E.P.R.), Mulliken-Walsh, and electrostatic force theories. Indicates that although the V.S.E.P.R. theory has more advantages for elementary courses, an explanation of the best features of the different theories offers students a better…

  7. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  8. Deterministic photon-emitter coupling in chiral photonic circuits

    NASA Astrophysics Data System (ADS)

    Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter

    2015-09-01

    Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.

  9. Deterministic photon-emitter coupling in chiral photonic circuits.

    PubMed

    Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter

    2015-09-01

    Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.

  10. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and...

  11. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

  12. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and...

  13. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

  14. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and...

  15. 30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and...

  16. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

  17. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

  18. 30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare..., and bare signal wires shall be adequately guarded: (a) At all points where men are required to work or...

  19. Wear mechanisms in a nonrotating wire rope

    SciTech Connect

    Schrems, K.K.; Dogan, C.P.; Hawk, J.A.

    1995-04-01

    A nonrotating wire rope used in main hoist operations is being examined by the US Bureau of Mines to determine operative wear mechanisms. Typically, bending and loading the ropes during service cause small, localized movements at interwire contacts, leading to material loss through wear.The cumulative effect of both material loss by wear and wire breakage by fatigue failure accelerates rope retirement. If the macroscopic mechanics of wire rope failure are to be understood, microscopic deformation and degradation processes must be identified and quantified. As a first step in this study, interwire wear and deformation were studied using a combination of scanning electron microscopy and hardness measurements. Both fretting and abrasive wear were identified as wear mechanisms. Preferential sites for fretting and abrasive wear were identified and are discussed regarding rope construction and geometry and the tribo-system.

  20. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  1. Thin wire pointing method

    NASA Technical Reports Server (NTRS)

    Green, G.; Mattauch, R. J. (Inventor)

    1983-01-01

    A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

  2. Research on quantum efficiency of GaN wire photocathode

    NASA Astrophysics Data System (ADS)

    Xia, Sihao; Liu, Lei; Diao, Yu; Kong, Yike

    2017-02-01

    On the basis of three-dimensional continuity equation in semiconductors and finite difference method, the carrier concentration and the quantum efficiency of GaN wire photocathode as a function of incident photon energy are achieved. Results show that the quantum efficiency of the wire photocathode is largely enhanced compared with the conventional planar photocathode. The superiority of the wire photocathode is reflected in its structure with surrounding surfaces. The quantum efficiency of the wire photocathode largely depends on the wire width, surface reflectivity, surface escape probability and incident angle of light. The back interface recombination rate, however, has little influences on the quantum efficiency of the wire photocathode. The simulation results suggest that the optimal width for photoemission is 150-200 nm. Besides, the quantum efficiency increases and decreases linearly with increasing surface escape probability and surface reflectivity, respectively. With increasing ratio of wire spacing to wire height, the optimal incident angle of light is reduced. These simulations are expected to guide the preparation of a better performing GaN wire photocathode.

  3. Sintered wire annode

    DOEpatents

    Falce, Louis R.; Ives, R. Lawrence

    2007-12-25

    A plurality of high atomic number wires are sintered together to form a porous rod that is parted into porous disks which will be used as x-ray targets. A thermally conductive material is introduced into the pores of the rod, and when a stream of electrons impinges on the sintered wire target and generates x-rays, the heat generated by the impinging x-rays is removed by the thermally conductive material interspersed in the pores of the wires.

  4. Wire-inhomogeneity detector

    DOEpatents

    Gibson, G.H.; Smits, R.G.; Eberhard, P.H.

    1982-08-31

    A device for uncovering imperfections in electrical conducting wire, particularly superconducting wire, by detecting variations in eddy currents. Eddy currents effect the magnetic field in a gap of an inductor, contained in a modified commercial ferrite core, through which the wire being tested is passed. A small increase or decrease in the amount of conductive material, such as copper, in a fixed cross section of wire will unbalance a bridge used to measure the impedance of the inductor, tripping a detector and sounding an alarm.

  5. Concealed wire tracing apparatus

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    An apparatus and method that combines a signal generator and a passive signal receiver to detect and record the path of partially or completely concealed electrical wiring without disturbing the concealing surface is disclosed. The signal generator applies a series of electrical pulses to the selected wiring of interest. The applied pulses create a magnetic field about the wiring that can be detected by a coil contained within the signal receiver. An audible output connected to the receiver and driven by the coil reflects the receivers position with respect to the wiring. The receivers audible signal is strongest when the receiver is directly above the wiring and the long axis of the receivers coil is parallel to the wiring. A marking means is mounted on the receiver to mark the location of the wiring as the receiver is directed over the wiring's concealing surface. Numerous marks made on various locations of the concealing surface will trace the path of the wiring of interest. 4 figs.

  6. Weld Wire Investigation Summary

    SciTech Connect

    Cunningham, M.A.

    1999-03-22

    After GTA welding reservoir A production/process prove-in assemblies, X-ray examination detected a lack of sidewall fusion. After examining several possible causes, it was determined that the weld wire filler metal was responsible, particularly the wire cleaning process. The final conclusion was that the filler wire must be abrasively cleaned in a particular manner to perform as required. The abrasive process was incorporated into the wire material specification, ensuring consistency for all reservoir GTA welding at AlliedSignal Federal Manufacturing and Technologies (FM and T).

  7. 1998 wire development workshop proceedings

    SciTech Connect

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development.

  8. VIEW SOUTHEASTBUILDING 4 NO. 1 WIRE MILL (1871) WIRE DRAWING ...

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

    VIEW SOUTHEAST-BUILDING 4 NO. 1 WIRE MILL (1871) WIRE DRAWING MACHINE - John A. Roebling's Sons Company & American Steel & Wire Company, South Broad, Clark, Elmer, Mott & Hudson Streets, Trenton, Mercer County, NJ

  9. 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.

  10. Surface waves in a magnetized ferrite slab filled with a wire medium

    NASA Astrophysics Data System (ADS)

    Nefedov, I. S.; Soloviev, A. S.; Tarot, A. C.; Abdouni, W.

    2009-06-01

    Novel metamaterial, based on wire medium embedded into magnetized ferrite, is studied. Waves in unbounded ferrites filled with wire media, surface wave at the interface of this metamaterial and the air as well as waves in a ferrite slab adjacent to a wire medium are considered. Different geometries of wires arrangement and different magnetization directions are discussed. Effective permeability was introduced for the case where both plasma and magnetic properties take place. Dispersion diagrams and applicability of the Drude model for the description of the wire medium in a host matrix, possessing high permittivity and permeability, are discussed.

  11. Commercial and Industrial Wiring.

    ERIC Educational Resources Information Center

    Kaltwasser, Stan; Flowers, Gary

    This module is the third in a series of three wiring publications, includes additional technical knowledge and applications required for job entry in the commercial and industrial wiring trade. The module contains 15 instructional units that cover the following topics: blueprint reading and load calculations; tools and equipment; service;…

  12. Imagination Visualized in Wire.

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2003-01-01

    Describes an art lesson achieved with a Very Special Artist (VSA) in residence for sixth- and seventh-grade students in which they created wire sculptures. Discusses how the VSA taught the students. Includes a list of art materials and characteristics of wire. (CMK)

  13. Imagination Visualized in Wire.

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2003-01-01

    Describes an art lesson achieved with a Very Special Artist (VSA) in residence for sixth- and seventh-grade students in which they created wire sculptures. Discusses how the VSA taught the students. Includes a list of art materials and characteristics of wire. (CMK)

  14. 2016 MOST WIRED.

    PubMed

    Barr, Paul; Butcher, Lola; Hoppszallern, Suzanna

    2016-07-01

    This year's IT survey shows that hospitals are aggressively fighting cyber crime and looking for ways to use data to help in the transition to value-based care. Find out who made the 2016 lists of Most Wired, Most Advanced, Most Improved and Most Wired-Small and Rural.

  15. Synthetic Landau levels for photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-06-01

    Synthetic photonic materials are an emerging platform for exploring the interface between microscopic quantum dynamics and macroscopic material properties. Photons experiencing a Lorentz force develop handedness, providing opportunities to study quantum Hall physics and topological quantum science. Here we present an experimental realization of a magnetic field for continuum photons. We trap optical photons in a multimode ring resonator to make a two-dimensional gas of massive bosons, and then employ a non-planar geometry to induce an image rotation on each round-trip. This results in photonic Coriolis/Lorentz and centrifugal forces and so realizes the Fock-Darwin Hamiltonian for photons in a magnetic field and harmonic trap. Using spatial- and energy-resolved spectroscopy, we track the resulting photonic eigenstates as radial trapping is reduced, finally observing a photonic Landau level at degeneracy. To circumvent the challenge of trap instability at the centrifugal limit, we constrain the photons to move on a cone. Spectroscopic probes demonstrate flat space (zero curvature) away from the cone tip. At the cone tip, we observe that spatial curvature increases the local density of states, and we measure fractional state number excess consistent with the Wen-Zee theory, providing an experimental test of this theory of electrons in both a magnetic field and curved space. This work opens the door to exploration of the interplay of geometry and topology, and in conjunction with Rydberg electromagnetically induced transparency, enables studies of photonic fractional quantum Hall fluids and direct detection of anyons.

  16. Photonic Crystal Laser Accelerator Structures

    SciTech Connect

    Cowan, Benjamin M

    2003-05-21

    Photonic crystals have great potential for use as laser-driven accelerator structures. A photonic crystal is a dielectric structure arranged in a periodic geometry. Like a crystalline solid with its electronic band structure, the modes of a photonic crystal lie in a set of allowed photonic bands. Similarly, it is possible for a photonic crystal to exhibit one or more photonic band gaps, with frequencies in the gap unable to propagate in the crystal. Thus photonic crystals can confine an optical mode in an all-dielectric structure, eliminating the need for metals and their characteristic losses at optical frequencies. We discuss several geometries of photonic crystal accelerator structures. Photonic crystal fibers (PCFs) are optical fibers which can confine a speed-of-light optical mode in vacuum. Planar structures, both two- and three-dimensional, can also confine such a mode, and have the additional advantage that they can be manufactured using common microfabrication techniques such as those used for integrated circuits. This allows for a variety of possible materials, so that dielectrics with desirable optical and radiation-hardness properties can be chosen. We discuss examples of simulated photonic crystal structures to demonstrate the scaling laws and trade-offs involved, and touch on potential fabrication processes.

  17. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  18. Signature geometry and quantum engineering

    NASA Astrophysics Data System (ADS)

    Samociuk, Stefan

    2013-09-01

    As the operating frequency of electromagnetic based devices increase, physical design geometry is playing an ever more important role. Evidence is considered in support of a relationship between the dimensionality of primitive geometric forms, such as transistors, and corresponding electromagnetic coupling efficiency. The industry of electronics is defined as the construction of devices by the patterning of primitive forms to physical materials. Examples are given to show the evolution of these primitives, down to nano scales, are requiring exacting geometry and three dimensional content. Consideration of microwave monolithic integrated circuits,(MMIC), photonics and metamaterials,(MM), support this trend and also add new requirements of strict geometric periodicity and multiplicity. Signature geometries,(SG), are characterized by distinctive attributes and examples are given. The transcendent form transcode algorithm, (TTA) is introduced as a multi dimensional SG and its use in designing photonic integrated circuits and metamaterials is discussed . A creative commons licensed research database, TRANSFORM, containing TTA geometries in OASIS file formats is described. An experimental methodology for using the database is given. Multidimensional SG and extraction of three dimensional cross sections as primitive forms is discussed as a foundation for quantum engineering and the exploitation of phenomena other than the electromagnetic.

  19. Energy Resolution in High Pressure Xenon Gas Using Electroluminescence in Parallel Wire Grids vs. Crossed Wire Meshes

    NASA Astrophysics Data System (ADS)

    Sofka, Clement; White, James

    2013-04-01

    Several rare event searches (e.g. detection of dark matter particles and neutrinoless double beta decay) are ongoing around the globe utilizing electroluminescent (EL) light collection from noble elements in drift chambers. These detectors use various wire geometries to achieve an EL gap that is optimized for light production, light collection, and energy resolution. We investigate the energy resolution of a parallel wire geometry and compare it to an EL gap composed of two crossed meshes in a high pressure gaseous xenon (GXe) drift chamber. The design, construction and results will be discussed.

  20. Next Generation Wiring

    NASA Technical Reports Server (NTRS)

    Medelius, Petro; Jolley, Scott; Fitzpatrick, Lilliana; Vinje, Rubiela; Williams, Martha; Clayton, LaNetra; Roberson, Luke; Smith, Trent; Santiago-Maldonado, Edgardo

    2007-01-01

    Wiring is a major operational component on aerospace hardware that accounts for substantial weight and volumetric space. Over time wire insulation can age and fail, often leading to catastrophic events such as system failure or fire. The next generation of wiring must be reliable and sustainable over long periods of time. These features will be achieved by the development of a wire insulation capable of autonomous self-healing that mitigates failure before it reaches a catastrophic level. In order to develop a self-healing insulation material, three steps must occur. First, methods of bonding similar materials must be developed that are capable of being initiated autonomously. This process will lead to the development of a manual repair system for polyimide wire insulation. Second, ways to initiate these bonding methods that lead to materials that are similar to the primary insulation must be developed. Finally, steps one and two must be integrated to produce a material that has no residues from the process that degrades the insulating properties of the final repaired insulation. The self-healing technology, teamed with the ability to identify and locate damage, will greatly improve reliability and safety of electrical wiring of critical systems. This paper will address these topics, discuss the results of preliminary testing, and remaining development issues related to self-healing wire insulation.

  1. Enrichment Activities for Geometry.

    ERIC Educational Resources Information Center

    Usiskin, Zalman

    1983-01-01

    Enrichment activities that teach about geometry as they instruct in geometry are given for some significant topics. The facets of geometry included are tessellations, round robin tournaments, geometric theorems on triangles, and connections between geometry and complex numbers. (MNS)

  2. Orbiter Kapton wire operational requirements and experience

    NASA Technical Reports Server (NTRS)

    Peterson, R. V.

    1994-01-01

    The agenda of this presentation includes the Orbiter wire selection requirements, the Orbiter wire usage, fabrication and test requirements, typical wiring installations, Kapton wire experience, NASA Kapton wire testing, summary, and backup data.

  3. Orbiter Kapton wire operational requirements and experience

    NASA Astrophysics Data System (ADS)

    Peterson, R. V.

    1994-09-01

    The agenda of this presentation includes the Orbiter wire selection requirements, the Orbiter wire usage, fabrication and test requirements, typical wiring installations, Kapton wire experience, NASA Kapton wire testing, summary, and backup data.

  4. The study of hard x-ray emission and electron beam generation in wire array Z-pinch and X-pinch plasmas at university-scale generators

    NASA Astrophysics Data System (ADS)

    Shrestha, Ishor Kumar

    The studies of hard x-ray (HXR) emission and electron beam generation in Z-pinch plasmas are very important for Inertial Confinement Fusion (ICF) research and HXR emission application for sources of K-shell and L-shell radiation. Energetic electron beams from Z-pinch plasmas are potentially a problem in the development of ICF. The electron beams and the accompanying HXR emission can preheat the fuel of a thermonuclear target, thereby preventing the fuel compression from reaching densities required for the ignition of a fusion reaction. The photons above 3-4 keV radiated from a Z pinch can provide detailed information about the high energy density plasmas produced at stagnation. Hence, the investigation of characteristics of hard x-rays and electron beams produced during implosions of wire array loads on university scale-generators may provide important data for future ICF, sources of K-shell and L-shell radiations and basic plasma research. This dissertation presents the results of experimental studies of HXR and electron beam generation in wire-array and X-pinch on the 1.7 MA, 100-ns current rise time Zebra generator at University of Nevada, Reno and 1-MA 100-ns current rise-time Cornell Beam Research Accelerator (COBRA) at Cornell University. The experimental study of characteristics of HXR produced by multi-planar wire arrays, compact cylindrical wire array (CCWA) and nested cylindrical wire array (NCWA) made from Al, Cu, Mo, Ag, W and Au were analyzed. The dependence of the HXR yield and power on geometry of the load, the wire material, and load mass was observed. The presence of aluminum wires in the load with the main material such as stainless steel, Cu, Mo, Ag, W or Au in combined wire array decreases HXR yield. The comparison of emission characteristics of HXR and generation of electron beams in CCWA and NCWA on both the high impedance Zebra generator and low impedance COBRA generator were investigated. Some of the "cold" K- shell spectral lines (0.7-2.3

  5. Development of the Cylindrical Wire Electrical Discharge Machining Process.

    SciTech Connect

    McSpadden, SB

    2002-01-22

    Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. A precise, flexible, and corrosion-resistant underwater rotary spindle was designed and added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. A detailed spindle error analysis identifies the major source of error at different frequency. The mathematical model for the material removal of cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the 2D wire EDM, higher maximum material removal rates may be achieved in the cylindrical wire EDM. This study also investigates the surface integrity and roundness of parts created by the cylindrical wire EDM process. For carbide parts, an arithmetic average surface roughness and roundness as low as 0.68 and 1.7 {micro}m, respectively, can be achieved. Surfaces of the cylindrical EDM parts were examined using Scanning Electron Microscopy (SEM) to identify the craters, sub-surface recast layers and heat-affected zones under various process parameters. This study has demonstrated that the cylindrical wire EDM process parameters can be adjusted to achieve either high material removal rate or good surface integrity.

  6. Faking ordinary photons by displaced dark photon decays

    NASA Astrophysics Data System (ADS)

    Tsai, Yuhsin; Wang, Lian-Tao; Zhao, Yue

    2017-01-01

    A light metastable dark photon decaying into a collimated electron/positron pair can fake a photon, either converted or unconverted, at the LHC. The detailed object identification relies on the specifics of the detector and strategies for the reconstruction. We study the fake rate based on the ATLAS (CMS) detector geometry and show that it can be O(1) with a generic choice of parameters. Especially, the probability of being registered as a photon is angular dependent. Such detector effects can induce bias to measurements on certain properties of new physics. In this paper, we consider the scenario where dark photons in final states are from a heavy resonance decay. Consequently, the detector effects can dramatically affect the results when determining the spin of a resonance. Further, if the decay products from the heavy resonance are one photon and one dark photon, which has a large probability to fake a diphoton event, the resonance is allowed to be a vector. Because of the difference in detectors, the cross sections measured in ATLAS and CMS do not necessarily match. Furthermore, if the diphoton signal is given by the dark photons, the standard model Z γ and Z Z final states do not necessarily come with the γ γ channel, which is a unique signature in our scenario. The issue studied here is relevant also for any future new physics searches with photon(s) in the final state. We discuss possible ways of distinguishing dark photon decay and a real photon in the future.

  7. Generating single microwave photons in a circuit.

    PubMed

    Houck, A A; Schuster, D I; Gambetta, J M; Schreier, J A; Johnson, B R; Chow, J M; Frunzio, L; Majer, J; Devoret, M H; Girvin, S M; Schoelkopf, R J

    2007-09-20

    Microwaves have widespread use in classical communication technologies, from long-distance broadcasts to short-distance signals within a computer chip. Like all forms of light, microwaves, even those guided by the wires of an integrated circuit, consist of discrete photons. To enable quantum communication between distant parts of a quantum computer, the signals must also be quantum, consisting of single photons, for example. However, conventional sources can generate only classical light, not single photons. One way to realize a single-photon source is to collect the fluorescence of a single atom. Early experiments measured the quantum nature of continuous radiation, and further advances allowed triggered sources of photons on demand. To allow efficient photon collection, emitters are typically placed inside optical or microwave cavities, but these sources are difficult to employ for quantum communication on wires within an integrated circuit. Here we demonstrate an on-chip, on-demand single-photon source, where the microwave photons are injected into a wire with high efficiency and spectral purity. This is accomplished in a circuit quantum electrodynamics architecture, with a microwave transmission line cavity that enhances the spontaneous emission of a single superconducting qubit. When the qubit spontaneously emits, the generated photon acts as a flying qubit, transmitting the quantum information across a chip. We perform tomography of both the qubit and the emitted photons, clearly showing that both the quantum phase and amplitude are transferred during the emission. Both the average power and voltage of the photon source are characterized to verify performance of the system. This single-photon source is an important addition to a rapidly growing toolbox for quantum optics on a chip.

  8. Superconducting wire manufactured

    NASA Astrophysics Data System (ADS)

    Fu, Yuexian; Sun, Yue; Xu, Shiming; Peng, Ying

    1985-10-01

    The MF Nb/Cu Extrusion Tube Method was used to manufacture 3 kg of stable practical MF Nb2Sn composite superconducting wire containing pure Cu(RRR approx. 200)/Ta. The draw state composite wire diameter was 0.56 mm, it contained 11,448 x 2.6 micron Nb core, and the twist distance was 1.5 cm. The composite wire cross-section was pure Cu/Ta/11,448 Nb core/Cu/ 91Sn-Cu; containing 22.8 v. % pure Cu, 13.3 v. % Ta; within the Ta layer to prevent Sn diffusion. The wire was sheathed in nonalkaline glass fiber as an insulating layer. A section of wire weighing 160 g was cut off and coiled it into a small solenoid. After reaction diffusion processing at 675 C/30 and curing by vacuum dipping in paraffin, it was measured in a Nb-Ti backfield of 7.2 T intensity, a current of 129 A was passed through the Nb3Sn solenoid and produced a strength of 2.5 T, the overall magnetic field intensity of the composite magnet reached 9.7 T. At this time, the wire full current density J sub c.w. = 5.2 x 10 to the 4th power A/sq cm; the effective current density J sub c (Nb + Sn - Cu) = 8.2 x 10 to the 4th power A/sq cm.

  9. Cavitation during wire brushing

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zou, Jun; Ji, Chen

    2016-11-01

    In our daily life, brush is often used to scrub the surface of objects, for example, teeth, pots, shoes, pool, etc. And cleaning rust and stripping paint are accomplished using wire brush. Wire brushes also can be used to clean the teeth for large animals, such as horses, crocodiles. By observing brushing process in water, we capture the cavitation phenomenon on the track of moving brush wire. It shows that the cavitation also can affect the surface. In order to take clear and entire pictures of cavity, a simplified model of one stainless steel wire brushing a boss is adopted in our experiment. A transparent organic tank filled with deionized water is used as a view box. And a high speed video camera is used to record the sequences. In experiment, ambient pressure is atmospheric pressure and deionized water temperature is kept at home temperature. An obvious beautiful flabellate cavity zone appears behind the moving steel wire. The fluctuation of pressure near cavity is recorded by a hydrophone. More movies and pictures are used to show the behaviors of cavitation bubble following a restoring wire. Beautiful tracking cavitation bubble cluster is captured and recorded to show.

  10. Miniaturized Linear Wire Ion Trap Mass Analyzer.

    PubMed

    Wu, Qinghao; Li, Ailin; Tian, Yuan; Zare, Richard N; Austin, Daniel E

    2016-08-02

    We report a linear ion trap (LIT) in which the electric field is formed by fine wires held under tension and accurately positioned using holes drilled in two end plates made of plastic. The coordinates of the hole positions were optimized in simulation. The stability diagram and mass spectra using boundary ejection were compared between simulation and experiment and good agreement was found. The mass spectra from experiments show peak widths (fwhm) in units of mass-to-charge of around 0.38 Th using a scan rate of 3830 Th/s. The limits of detection are 137 ppbv and 401 ppbv for benzene and toluene, respectively. Different sizes of the wire ion trap can be easily fabricated by drilling holes in scaled positions. Other distinguishing features, such as high ion and photon transmission, low capacitance, high tolerance to mechanical and assembly error, and low weight, are discussed.

  11. Splicing Wires Permanently With Explosives

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Kushnick, Anne C.

    1990-01-01

    Explosive joining process developed to splice wires by enclosing and metallurgically bonding wires within copper sheets. Joints exhibit many desirable characteristics, 100-percent conductivity and strength, no heat-induced annealing, no susceptibility to corrosion in contacts between dissimilar metals, and stability at high temperature. Used to join wires to terminals, as well as to splice wires. Applicable to telecommunications industry, in which millions of small wires spliced annually.

  12. IR photodetector based on rectangular quantum wire in magnetic field

    SciTech Connect

    Jha, Nandan

    2014-04-24

    In this paper we study rectangular quantum wire based IR detector with magnetic field applied along the wires. The energy spectrum of a particle in rectangular box shows level repulsions and crossings when external magnetic field is applied. Due to this complex level dynamics, we can tune the spacing between any two levels by varying the magnetic field. This method allows user to change the detector parameters according to his/her requirements. In this paper, we numerically calculate the energy sub-band levels of the square quantum wire in constant magnetic field along the wire and quantify the possible operating wavelength range that can be obtained by varying the magnetic field. We also calculate the photon absorption probability at different magnetic fields and give the efficiency for different wavelengths if the transition is assumed between two lowest levels.

  13. Geometry in the Computer Age.

    ERIC Educational Resources Information Center

    Scott, Paul

    1988-01-01

    Discusses the use of computer graphics in the teaching of geometry. Describes five types of geometry: Euclidean geometry, transformation geometry, coordinate geometry, three-dimensional geometry, and geometry of convex sets. (YP)

  14. Molecular wires self-assembled on a graphite surface.

    PubMed

    Riemann, Andreas; Nelson, Brittany

    2009-04-21

    We report a scanning tunneling microscopy study of the amino acid l-methionine on highly ordered pyrolytic graphite deposited under ambient conditions. Our experiments demonstrate the ability of l-methionine to form highly regular structures on the surface of the graphite template. By means of self-assembly, the amino acid arranges itself into an array of molecular wires, i.e., well-ordered stripes of uniform width and separation. The spacing of these wires can be controlled with the deposition amount of the amino acid, whereas the width stays constant. The width of the wires is determined by two methionine molecules arranged with their carboxyl group facing each other. The regular separation of individual wires suggest a long-range interaction among them. Molecular mechanics calculations are used to compare the experimental results with a basic model for the methionine configuration on the surface. A model for the adsorption geometry of methionine on graphite is presented.

  15. Ionization coefficient approach to modeling breakdown in nonuniform geometries.

    SciTech Connect

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Nicolaysen, Scott D.

    2003-11-01

    This report summarizes the work on breakdown modeling in nonuniform geometries by the ionization coefficient approach. Included are: (1) fits to primary and secondary ionization coefficients used in the modeling; (2) analytical test cases for sphere-to-sphere, wire-to-wire, corner, coaxial, and rod-to-plane geometries; a compilation of experimental data with source references; comparisons between code results, test case results, and experimental data. A simple criterion is proposed to differentiate between corona and spark. The effect of a dielectric surface on avalanche growth is examined by means of Monte Carlo simulations. The presence of a clean dry surface does not appear to enhance growth.

  16. Wire brush fastening device

    SciTech Connect

    Meigs, R.A.

    1993-08-31

    A fastening device is provided which is a variation on the conventional nut and bolt. The bolt has a longitudinal axis and threading helically affixed thereon along the longitudinal axis. A nut having a bore extending therethrough is provided. The bore of the nut has a greater diameter than the diameter of the bolt so the bolt can extend through the bore. An array of wire bristles are affixed within the bore so as to form a brush. The wire bristles extend inwardly from the bore and are constructed and arranged of the correct size, length and stiffness to guide the bolt within the bore and to restrain the bolt within the bore as required. A variety of applications of the wire brush nut are disclosed, including a bolt capture device and a test rig apparatus.

  17. Wire brush fastening device

    DOEpatents

    Meigs, R.A.

    1995-09-19

    A fastening device is provided which is a variation on the conventional nut and bolt. The bolt has a longitudinal axis and threading helically affixed thereon along the longitudinal axis. A nut having a bore extending therethrough is provided. The bore of the nut has a greater diameter than the diameter of the bolt so the bolt can extend through the bore. An array of wire bristles are affixed within the bore so as to form a brush. The wire bristles extend inwardly from the bore and are constructed and arranged of the correct size, length and stiffness to guide the bolt within the bore and to restrain the bolt within the bore as required. A variety of applications of the wire brush nut are disclosed, including a bolt capture device and a test rig apparatus. 13 figs.

  18. Wire brush fastening device

    DOEpatents

    Meigs, Richard A.

    1995-01-01

    A fastening device is provided which is a variation on the conventional nut and bolt. The bolt has a longitudinal axis and threading helically affixed thereon along the longitudinal axis. A nut having a bore extending therethrough is provided. The bore of the nut has a greater diameter than the diameter of the bolt so the bolt can extend through the bore. An array of wire bristles are affixed within the bore so as to form a brush. The wire bristles extend inwardly from the bore and are constructed and arranged of the correct size, length and stiffness to guide the bolt within the bore and to restrain the bolt within the bore as required. A variety of applications of the wire brush nut are disclosed, including a bolt capture device and a test rig apparatus.

  19. Developments in plastic wire chambers operated in the limited streamer mode (LSM detectors)

    NASA Astrophysics Data System (ADS)

    Laakso, Mikko; Kurvinen, Kari; Orava, Risto

    1988-12-01

    We have calculated the photon detection efficiency of a wire chamber constructed with conductive nylon-66 plastic as cathode material in the photon energy range of 100 keV-1 MeV. The calculated results are compared with the results obtained with a Monte Carlo simulation using the FLUKA [1] transport code and with experimental results. We have also calculated the efficiency for copper and compared these two cathode materials. The comparison shows that wire chambers with nylon and copper cathodes are equally efficient in detecting the 100 keV-1 MeV photons. Furthermore, we have studied the different physical processes contributing to photon detection as well as the detection efficiency as a function of cathode thickness. Finally, we report some results from the first LSM detector operational tests performed with our new wire chamber testing device.

  20. 2. TYPICAL OVERHEAD WIRE CONSTRUCTION CURVE GUY WIRE ARRANGEMENT ...

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

    2. TYPICAL OVERHEAD WIRE CONSTRUCTION - CURVE GUY WIRE ARRANGEMENT (ABANDONED WEST LEG OF WYE AT SIXTH AVENUE AND PINE STREET) - Yakima Valley Transportation Company Interurban Railroad, Trackage, Yakima, Yakima County, WA

  1. Direction Controlled Coulomb Drag in Coupled One-Dimensional Quantum Wires

    NASA Astrophysics Data System (ADS)

    Yamamoto, Michihisa

    2007-03-01

    In a one-dimensional electron gas (1DEG) with sufficiently low density at low temperature, Coulomb interaction becomes so dominant that Wigner crystallization can occur. Wigner crystal (WC) is generally characterized by collective motion of electrons and strong incompressibility. Therefore, in the presence of an external electrostatic potential, electrons forming a WC do not contribute to microscopic screening and only respond rigidly, whereas those of a Fermi liquid (FL) freely move to screen the external potential and produce a correlation hole. In this work we show that the difference between WC and FL allows us to control the direction of Coulomb drag in coupled pairs of 1DEG wires, each having two 2DEG leads. We prepare parallel coupled pairs of quantum wires in a 2DEG defined by Schottky gates to study the current drag between the two wires. The distance between the two wires and the electron density in each wire are all tunable with gate voltages. We inject a constant current into one of the wires (drive wire) and measure the induced drag current (or voltage drop for Idrag = 0) in the other wire (drag wire). Electrons in the drive wire usually drag electrons in the drag wire in the same direction because momentum is conserved in Coulombic scattering between the wires. However, when the electron density in the drive wire is sufficiently low that the drive wire has charge inhomogeneity and the electrons in the drag wire are strongly correlated, i.e. at low density, high perpendicular magnetic field and low temperature, the direction of the drag current can be reversed. The sign reversal occurs only when the drive wire is adjacent to the boundary between the drag wire and its lead, and can be controlled by changing the geometry of the coupled wires. These behaviors can be modeled by electron pump from WC in the drag wire to its 2DEG lead, driven by particle-like electrons in the drive wire. The drive wire electrons induce a positive screening charge only in the

  2. Flying wires at Fermilab

    SciTech Connect

    Gannon, J.; Crawford, C.; Finley, D.; Flora, R.; Groves, T.; MacPherson, M.

    1989-03-01

    Transverse beam profile measurement systems called ''Flying Wires'' have been installed and made operational in the Fermilab Main Ring and Tevatron accelerators. These devices are used routinely to measure the emittance of both protons and antiprotons throughout the fill process, and for emittance growth measurements during stores. In the Tevatron, the individual transverse profiles of six proton and six antiproton bunches are obtained simultaneously, with a single pass of the wire through the beam. Essential features of the hardware, software, and system operation are explained in the rest of the paper. 3 refs., 4 figs.

  3. Multicolor photonic crystal laser array

    SciTech Connect

    Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

    2015-04-28

    A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

  4. Topological photonics: an observation of Landau levels for optical photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Sommer, Ariel; Simon, Jonathan

    Creating photonic materials with nontrivial topological characteristics has seen burgeoning interest in recent years; however, a major route to topology, a magnetic field for continuum photons, has remained elusive. We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We will discuss the conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. This work was supported by DOE, DARPA, and AFOSR.

  5. Wiring for space applications program

    NASA Astrophysics Data System (ADS)

    Hammoud, Ahmad

    1994-01-01

    The insulation testing and analysis consists of: identifying and prioritizing NASA wiring requirements; selecting candidate wiring constructions; developing test matrix and formulating test program; managing, coordinating, and conducting tests; and analyzing and documenting data, establishing guidelines and recommendations.

  6. One hundred angstrom niobium wire

    NASA Technical Reports Server (NTRS)

    Cline, H. E.; Rose, R. M.; Wulff, J.

    1968-01-01

    Composite of fine niobium wires in copper is used to study the size and proximity effects of a superconductor in a normal matrix. The niobium rod was drawn to a 100 angstrom diameter wire on a copper tubing.

  7. Easily-wired toggle switch

    NASA Technical Reports Server (NTRS)

    Dean, W. T.; Stringer, E. J.

    1979-01-01

    Crimp-type connectors reduce assembly and disassembly time. With design, no switch preparation is necessary and socket contracts are crimped to wires inserted in module attached to back of toggle switch engaging pins inside module to make electrical connections. Wires are easily removed with standard detachment tool. Design can accommodate wires of any gage and as many terminals can be placed on switch as wire gage and switch dimensions will allow.

  8. SCALING UNDERWATER EXPLODING WIRES

    DTIC Science & Technology

    heat of detonation of TNT in calories per gram. This scaling behavior extends the law of similarity six decades in terms of weight, from pounds to micropounds. The peak pressure for exploding-wire phenomena has been obtained from data and is emprically expressed as pm = 26,800 (cube root of W/R) to

  9. Hopkins installs wire harnesses

    NASA Image and Video Library

    2013-11-24

    ISS038-E-008291 (24 Nov. 2013) --- NASA astronaut Michael Hopkins, Expedition 38 flight engineer, installs wire harnesses in the International Space Station?s Harmony node to support the installation of Ethernet video cables for the station?s local area network. These new cables will provide Ethernet connectivity to the visiting vehicles that dock to Harmony?s Earth-facing port.

  10. Gaseous wire detectors

    SciTech Connect

    Va'vra, J.

    1997-08-01

    This article represents a series of three lectures describing topics needed to understand the design of typical gaseous wire detectors used in large high energy physics experiments; including the electrostatic design, drift of electrons in the electric and magnetic field, the avalanche, signal creation, limits on the position accuracy as well as some problems one encounters in practical operations.

  11. A World without Wires

    ERIC Educational Resources Information Center

    Panettieri, Joseph C.

    2006-01-01

    The wireless bandwagon is rolling across Mississippi, picking up a fresh load of converts and turning calamity into opportunity. Traditional wired school networks, many of which unraveled during Hurricane Katrina, are giving way to advanced wireless mesh networks that frequently include voice-over-IP (VoIP) capabilities. Vendor funding is helping…

  12. Residential Wiring. Second Edition.

    ERIC Educational Resources Information Center

    Taylor, Mark; And Others

    This guide is designed to assist teachers conducting a course to prepare students for entry-level employment in the residential wiring trade. Included in the guide are six instructional units and the following sections of information for teachers: guidelines in using the unit components; academic and workplace skills classifications and…

  13. Improved wire chamber

    DOEpatents

    Atac, M.

    1987-05-12

    An improved gas mixture for use with proportional counter devices, such as Geiger-Mueller tubes and drift chambers. The improved gas mixture provides a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor. 2 figs.

  14. Debate: Wired versus Wireless.

    ERIC Educational Resources Information Center

    Meeks, Glenn; Nair, Prakash

    2000-01-01

    Debates the issue of investing in wiring schools for desktop computer networks versus using laptops and wireless networks. Included are cost considerations and the value of technology for learning. Suggestions include using wireless networks for existing schools, hardwiring computers for new construction, and not using computers for elementary…

  15. NewsWire, 2002.

    ERIC Educational Resources Information Center

    Byrom, Elizabeth, Ed.; Bingham, Margaret, Ed.; Bowman, Gloria, Ed.; Shoemaker, Dan, Ed.

    2002-01-01

    This document presents the 3 2002 issues of the newsletter "NewsWire," (volume 5). Issue Number One focuses on collaborative Web projects. This issue begins with descriptions of four individual projects: "iEARN"; "Operation RubyThroat"; "Follow the Polar Huskies!"; and "Log in Your Animal Roadkill!" Features that follow include: "Bringing the…

  16. Basic Wiring. Second Edition.

    ERIC Educational Resources Information Center

    Kaltwasser, Stan; And Others

    This guide is designed to assist teachers conducting a foundation course to prepare students for additional courses of training for entry-level employment in either the residential or commercial and industrial wiring trades. Included in the guide are 17 instructional units and the following sections of information for teachers: guidelines in using…

  17. Residential Wiring. Revised.

    ERIC Educational Resources Information Center

    Taylor, Mark

    This competency-based curriculum guide contains materials for conducting a course in residential wiring. A technically revised edition of the 1978 publication, the guide includes 28 units. Each instructional unit includes some or all of the following basic components: performance objectives, suggested activities for teachers and students,…

  18. One-wire thermocouple

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Staimach, C. J.

    1977-01-01

    Nickel alloy/constantan device accurately measures surface temperature at precise locations. Device is moderate in cost and simplifies fabrication of highly-instrumented seamless-surface heat-transfer models. Device also applies to metal surfaces if constantan wire has insulative coat.

  19. A World without Wires

    ERIC Educational Resources Information Center

    Panettieri, Joseph C.

    2006-01-01

    The wireless bandwagon is rolling across Mississippi, picking up a fresh load of converts and turning calamity into opportunity. Traditional wired school networks, many of which unraveled during Hurricane Katrina, are giving way to advanced wireless mesh networks that frequently include voice-over-IP (VoIP) capabilities. Vendor funding is helping…

  20. Reliable Wiring Harness

    NASA Technical Reports Server (NTRS)

    Gaspar, Kenneth C.

    1987-01-01

    New harness for electrical wiring includes plugs that do not loosen from vibration. Ground braids prevented from detaching from connectors and constrained so braids do not open into swollen "birdcage" sections. Spring of stainless steel encircles ground braid. Self-locking connector contains ratchet not only preventing connector from opening, but tightens when vibrated.

  1. WIRED — World Wide Web interactive remote event display

    NASA Astrophysics Data System (ADS)

    Ballaminut, A.; Colonello, C.; Dönszelmann, M.; van Herwijnen, E.; Köper, D.; Korhonen, J.; Litmaath, M.; Perl, J.; Theodorou, A.; Whiteson, D.; Wolff, E.

    2001-10-01

    WIRED ( http://wired.cern.ch/) is a framework, written in Java, to build High Energy Physics event displays that can be used across the network. To guarantee portability across all platforms, WIRED is implemented in the Java language and uses the Swing user interface component set. It can be used as a stand-alone application or as an applet inside a WWW browser. The graphical user interface allows for multiple views and for multiple controls acting on those views. A detector tree control is available to toggle the visibility of parts of the events and detector geometry. XML (Extensible Markup Language), RMI (Remote Method Invocation) and CORBA loaders can be used to load event data as well as geometry data, and to connect to FORTRAN, C, C++ and Java reconstruction programs. Non-linear and non-Cartesian projections (e.g., fisheye, ρ- φ, ρ- Z, φ- Z) provide special views to get a better understanding of events. A special Java interpreter allows physicists to write small scripts to interact with their data and its display. WIRED has grown to be a framework in use and under development in several HEP experiments (ATLAS, CHORUS, DELPHI, LHCb, BaBar, D0 and ZEUS). WIRED event displays have also proven to be useful to explain High Energy Physics to the general public. Both CERN, in its traveling exhibition and MicroCosm, and RAL, during its open days, have displays set up.

  2. A four-pixel single-photon pulse-position array fabricated from WSi superconducting nanowire single-photon detectors

    SciTech Connect

    Verma, V. B. Horansky, R.; Lita, A. E.; Mirin, R. P.; Nam, S. W.; Marsili, F.; Stern, J. A.; Shaw, M. D.

    2014-02-03

    We demonstrate a scalable readout scheme for an infrared single-photon pulse-position camera consisting of WSi superconducting nanowire single-photon detectors. For an N × N array, only 2 × N wires are required to obtain the position of a detection event. As a proof-of-principle, we show results from a 2 × 2 array.

  3. Extending wire rope service life

    SciTech Connect

    Not Available

    1982-06-01

    Selecting the proper wire rope is not a simple procedure. Wire rope is a precision mining machine with scores of moving parts. It is therefore important for mining equipment users to know wire rope and how it is designed and constructed. Good lubrication and regular inspection is important for a safe and long service life.

  4. 1997 wire development workshop: Proceedings

    SciTech Connect

    1997-04-01

    This conference is divided into the following sections: (1) First Generation Wires I; (2) First Generation Wires II; (3) Coated conductors I; and (4) Coated conductors II. Applications of the superconducting wires include fault current limiters, superconducting motors, transformers, and power transmission lines.

  5. Photonic Landau levels on cones

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-05-01

    Creating photonic materials with nontrivial topological characteristics has seen burgeoning interest in recent years; however, a major route to topology, a magnetic field for continuum photons, has remained elusive. We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We will discuss the conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids.

  6. Geometry in Medias Res

    ERIC Educational Resources Information Center

    Cukier, Mimi; Asdourian, Tony; Thakker, Anand

    2012-01-01

    Geometry provides a natural window into what it is like to do mathematics. In the world of geometry, playful experimentation is often more fruitful than following a procedure, and logic plus a few axioms can open new worlds. Nonetheless, teaching a geometry course in a way that combines both rigor and play can be difficult. Many geometry courses…

  7. Geometry in Medias Res

    ERIC Educational Resources Information Center

    Cukier, Mimi; Asdourian, Tony; Thakker, Anand

    2012-01-01

    Geometry provides a natural window into what it is like to do mathematics. In the world of geometry, playful experimentation is often more fruitful than following a procedure, and logic plus a few axioms can open new worlds. Nonetheless, teaching a geometry course in a way that combines both rigor and play can be difficult. Many geometry courses…

  8. Molecular wires, switches and memories

    NASA Astrophysics Data System (ADS)

    Chen, Jia

    Molecular electronics, an emerging field, makes it possible to build individual molecules capable of performing functions identical or analogous to present- day conductors, switches, or memories. These individual molecules, with a nano-meter scale characteristic length, can be designed and chemically synthesized with specific atoms, geometries and charge distribution. This thesis focuses on the design, and measurements of molecular wires, and related strategically engineered structures-molecular switches and memories. The experimental system relies on a thermodynamically driven self-assembling process to attach molecules onto substrate surfaces without intervention from outside. The following topics will be discussed: directed nanoscale manipulation of self-assembled molecules using scanning tunneling microscope; investigation on through-bond transport of nanoscale symmetric metal/conjugated self- assembled monolayers (SAM)/metal junctions, where non- Ohmic thermionic emission was observed to be the dominant process, with isocyanide-Pd contacts showing the lowest thermionic barrier of 0.22 eV; the first realization of robust and large reversible switching behavior in an electronic device that utilizes molecules containing redox centers as the active component, exhibiting negative differential resistance (NDR) and large on-off peak-to-valley ratio (PVR); observation of erasable storage of higher conductivity states in these redox- center containing molecular devices, and demonstration of a two-terminal electronically programmable and erasable molecular memory cell with long bit retention time.

  9. A new elastic slot system and V-wire mechanics.

    PubMed

    Wichelhaus, Andrea

    2017-09-01

    To biomechanically test a new elastic slot system and V-wire mechanics. Conventional twin and self-ligating brackets and the new elastodynamic bracket were biomechanically tested. The conventional brackets had a rectangular 0.022'' slot and the new elastodynamic bracket had a V-slot, a new slot geometry. Torque measurements were performed with 0.018'' × 0.025'' and 0.019'' × 0.025'' stainless steel (ss) archwires. A nickel-titanium V wire was used for the biomechanical measurements on the elastodynamic bracket. The measurements were done with the aid of a six-component measuring sensor. The results of the biomechanical testing revealed play in the brackets with rectangular slot geometry. The V slot in the elastodynamic bracket assured that the wire fit perfectly in the slot. Dynamic moments of 5 to 10 Nmm were transmitted without any play. No permanent deformation of the slot occurred in the new elastodynamic bracket because of the elastic slot. Control of torque for three-dimensional positioning of the teeth in the dental arch with rectangular slot geometry as used in straight-wire therapy is difficult. If torque is bent into the wire, because of the play there is a high risk that either too much, too little, or no moment is transmitted to the teeth. The V-slot archwire/bracket geometry in conjunction with nickel titanium composition has no play and allows a reduction of forces and moments with direct and continuous transmission of torque in the bracket. Because of the elasticity of the bracket, there is an upper limit to the moment possible.

  10. Wire mesh current collectors for passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Shrivastava, Naveen K.; Thombre, Shashikant B.; Motghare, Ramani V.

    2014-12-01

    This paper examines the feasibility of the stainless steel wire mesh as current collector in the passive direct methanol fuel cell (DMFCs-W). A novel single cell fixture is designed and fabricated. The cell performance is evaluated and compared with five different wire mesh current collectors. The supporting plates are optimized for every mesh. The performance of DMFCs-W is compared with the conventional passive DMFC which uses perforated metal plate as current collector (DMFC-P). The polarization tests and electrochemical impedance spectroscopy are performed to investigate the different aspects of the cell performance. The results reveal that the DMFCs-W yield better performance than the DMFC-P. Also, more uniform fuel distribution at catalyst layer and higher cell temperature is achieved with wire mesh current collectors. It is found that the wire mesh geometry has significant effect on the cell performance and the mesh made of relatively thick wires gives better cell performance. This study identifies the stainless steel wire mesh as promising material to be used as current collector and potential substitute to the perforated plate current collectors in the passive DMFC.

  11. TCPD: A micropattern photon detector hybrid for RICH applications

    NASA Astrophysics Data System (ADS)

    Hamar, G.; Varga, D.

    2017-03-01

    A micropattern and wire chamber hybrid has been constructed for UV photon detection, and its performance evaluated. It is revealed that such combination retains some key advantages of both the Thick-GEM primary and CCC secondary amplification stages, and results in a high gain gaseous photon detector with outstanding stability. Key features such as MIP suppression, detection efficiency and photon cluster size are discussed. The capability of the detector for UV photon detection has been established and proven with Cherenkov photons in particle beam tests.

  12. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    NASA Astrophysics Data System (ADS)

    Spurgeon, Joshua Michael

    Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

  13. Learning Geometry through Dynamic Geometry Software

    ERIC Educational Resources Information Center

    Forsythe, Sue

    2007-01-01

    In this article, the author investigates effective teaching and learning of geometrical concepts using dynamic geometry software (DGS). Based from her students' reactions to her project, the author found that her students' understanding of the concepts was better than if they had learned geometry through paper-based tasks. However, mixing computer…

  14. Learning Geometry through Dynamic Geometry Software

    ERIC Educational Resources Information Center

    Forsythe, Sue

    2007-01-01

    In this article, the author investigates effective teaching and learning of geometrical concepts using dynamic geometry software (DGS). Based from her students' reactions to her project, the author found that her students' understanding of the concepts was better than if they had learned geometry through paper-based tasks. However, mixing computer…

  15. From wires to cosmology

    NASA Astrophysics Data System (ADS)

    Amin, Mustafa A.; Baumann, Daniel

    2016-02-01

    We provide a statistical framework for characterizing stochastic particle production in the early universe via a precise correspondence to current conduction in wires with impurities. Our approach is particularly useful when the microphysics is uncertain and the dynamics are complex, but only coarse-grained information is of interest. We study scenarios with multiple interacting fields and derive the evolution of the particle occupation numbers from a Fokker-Planck equation. At late times, the typical occupation numbers grow exponentially which is the analog of Anderson localization for disordered wires. Some statistical features of the occupation numbers show hints of universality in the limit of a large number of interactions and/or a large number of fields. For test cases, excellent agreement is found between our analytic results and numerical simulations.

  16. Dental Arch Wire

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Straightening teeth is an arduous process requiring months, often years, of applying corrective pressure by means of arch wires-better known as brace-which may have to be changed several times in the course of treatment. A new method has been developed by Dr. George Andreasen, orthodontist and dental scientist at the University of Iowa. The key is a new type of arch wire material, called Nitinol, with exceptional elasticity which helps reduce the required number of brace changes. An alloy of nickel and titanium, Nitinol was originally developed for aerospace applications by the Naval Ordnance Laboratory, now the Naval Surface Weapons Laboratory, White Oaks, Maryland. NASA subsequently conducted additional research on the properties of Nitinol and on procedures for processing the metal.

  17. Wire insulation defect detector

    NASA Technical Reports Server (NTRS)

    Greulich, Owen R. (Inventor)

    2004-01-01

    Wiring defects are located by detecting a reflected signal that is developed when an arc occurs through the defect to a nearby ground. The time between the generation of the signal and the return of the reflected signal provides an indication of the distance of the arc (and therefore the defect) from the signal source. To ensure arcing, a signal is repeated at gradually increasing voltages while the wire being tested and a nearby ground are immersed in a conductive medium. In order to ensure that the arcing occurs at an identifiable time, the signal whose reflection is to be detected is always made to reach the highest potential yet seen by the system.

  18. From wires to cosmology

    SciTech Connect

    Amin, Mustafa A.; Baumann, Daniel E-mail: dbaumann@damtp.cam.ac.uk

    2016-02-01

    We provide a statistical framework for characterizing stochastic particle production in the early universe via a precise correspondence to current conduction in wires with impurities. Our approach is particularly useful when the microphysics is uncertain and the dynamics are complex, but only coarse-grained information is of interest. We study scenarios with multiple interacting fields and derive the evolution of the particle occupation numbers from a Fokker-Planck equation. At late times, the typical occupation numbers grow exponentially which is the analog of Anderson localization for disordered wires. Some statistical features of the occupation numbers show hints of universality in the limit of a large number of interactions and/or a large number of fields. For test cases, excellent agreement is found between our analytic results and numerical simulations.

  19. Design of a wire-mesh collimator for gamma cameras.

    PubMed

    Saripan, M Iqbal; Petrou, Maria; Wells, Kevin

    2007-09-01

    This paper presents a model of a wire-mesh collimator for a gamma camera that produces images of comparable quality as those produced with the conventional multihole collimator, but has about half the weight of the multihole collimator. The gamma camera and the collimator are simulated using the MCNPX code. Two final configurations of the wire-mesh collimator are proposed, and their performance is compared with other wire-mesh collimators and with the multihole collimator, using a point source, a planar square source, and two point sources, all in water. In all cases, photons with energy 140 keV are simulated. In addition, we use the simulation of a realistic phantom of a hot tumor in a warm background to assess the performance of our collimator in conjunction with an extended source.

  20. Making Superconducting Welds between Superconducting Wires

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I.; Eom, Byeong Ho

    2008-01-01

    A technique for making superconducting joints between wires made of dissimilar superconducting metals has been devised. The technique is especially suitable for fabrication of superconducting circuits needed to support persistent electric currents in electromagnets in diverse cryogenic applications. Examples of such electromagnets include those in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems and in superconducting quantum interference devices (SQUIDs). Sometimes, it is desirable to fabricate different parts of a persistent-current-supporting superconducting loop from different metals. For example, a sensory coil in a SQUID might be made of Pb, a Pb/Sn alloy, or a Cu wire plated with Pb/Sn, while the connections to the sensory coil might be made via Nb or Nb/Ti wires. Conventional wire-bonding techniques, including resistance spot welding and pressed contact, are not workable because of large differences between the hardnesses and melting temperatures of the different metals. The present technique is not subject to this limitation. The present technique involves the use (1) of a cheap, miniature, easy-to-operate, capacitor-discharging welding apparatus that has an Nb or Nb/Ti tip and operates with a continuous local flow of gaseous helium and (2) preparation of a joint in a special spark-discharge welding geometry. In a typical application, a piece of Nb foil about 25 m thick is rolled to form a tube, into which is inserted a wire that one seeks to weld to the tube (see figure). The tube can be slightly crimped for mechanical stability. Then a spark weld is made by use of the aforementioned apparatus with energy and time settings chosen to melt a small section of the niobium foil. The energy setting corresponds to the setting of a voltage to which the capacitor is charged. In an experiment, the technique was used to weld an Nb foil to a copper wire coated with a Pb/Sn soft solder, which is superconducting. The joint was evaluated as

  1. Wiring for aerospace applications

    NASA Technical Reports Server (NTRS)

    Christian, J. L., Jr.; Dickman, J. E.; Bercaw, R. W.; Myers, I. T.; Hammoud, A. N.; Stavnes, M.; Evans, J.

    1992-01-01

    In this paper, the authors summarize the current state of knowledge of arc propagation in aerospace power wiring and efforts by the National Aeronautics and Space Administration (NASA) towards the understanding of the arc tracking phenomena in space environments. Recommendations will be made for additional testing. A database of the performance of commonly used insulating materials will be developed to support the design of advanced high power missions, such as Space Station Freedom and Lunar/Mars Exploration.

  2. Superconducting magnet wire

    DOEpatents

    Schuller, Ivan K.; Ketterson, John B.; Banerjee, Indrajit

    1986-01-01

    A superconducting tape or wire with an improved critical field is formed of alternating layers of a niobium-containing superconductor such as Nb, NbTi, Nb.sub.3 Sn or Nb.sub.3 Ge with a thickness in the range of about 0.5-1.5 times its coherence length, supported and separated by layers of copper with each copper layer having a thickness in the range of about 170-600 .ANG..

  3. Printed wiring assembly cleanliness

    SciTech Connect

    Stephens, J.M.

    1992-12-01

    This work installed a product cleanliness test capability in a manufacturing environment. A previously purchased testing device was modified extensively and installed in a production department. The device, the testing process, and some soldering and cleaning variables were characterized to establish their relationship to the device output. The characterization provided information which will be required for cleanliness testing to be an adequate process control of printed wiring assembly soldering and cleaning processes.

  4. Plated wire memory subsystem

    NASA Technical Reports Server (NTRS)

    Reynolds, L.; Tweed, H.

    1972-01-01

    The work performed entailed the design, development, construction and testing of a 4000 word by 18 bit random access, NDRO plated wire memory for use in conjunction with a spacecraft imput/output unit and central processing unit. The primary design parameters, in order of importance, were high reliability, low power, volume and weight. A single memory unit, referred to as a qualification model, was delivered.

  5. Impact Wire Dislodges Obstructions

    NASA Technical Reports Server (NTRS)

    Ricklefs, Steven K.; Anders, Jeffrey E.

    1990-01-01

    Snakelike tool loosens trapped debris obstructing narrow passages in normally inaccessible locations. Flexible tool threaded into obstructed channel, much like common plumbing snake. Wire fed along inner tube of tool until tip reaches obstruction. Delivers impact from impact tool to obstruction. Designed for use in narrow, intricate coolant channels of rocket engine. Lends itself readily to modification for use in engine blocks, heat exchangers, general plumbing, and like.

  6. Magnetoconductance of quantum wires

    NASA Astrophysics Data System (ADS)

    Ferreira, Gerson J.; Sammarco, Filipe; Egues, Carlos

    2010-03-01

    At low temperatures the conductance of a quantum wires exhibit characteristic plate-aus due to the quantization of the transverse modes [1]. In the presence of high in-plane magnetic fields these spin-split transverse modes cross. Recently, these crossings were observed experimentally [2] via measurements of the differential conductance as a function of the gate voltage and the in-plane magnetic-field. These show structures described as either anti-crossings or magnetic phase transitions. Motivated by our previous works on magnetotransport in 2DEGs via the Spin Density Functional Theory (SDFT) [3], here we propose a similar model to investigate the magnetoconductance of quantum wires. We use (i) the SDFT via the Kohn-Sham self-consistent scheme within the local spin density approximation to obtain the electronic structure and (ii) the Landauer-Buettiker formalism to calculate the conductance of a quantum wire. Our results show qualitative agreement with the data of Ref. [2]. [1] B. J. van Wees et al., Phys. Rev. Lett. 60, 848 (1988). [2] A. C. Graham et al., Phys. Rev. Lett. 100, 226804 (2008). [3] H. J. P. Freire, and J. C. Egues, Phys. Rev. Lett. 99, 026801 (2007); G. J. Ferreira, and J. Carlos Egues, J. Supercond. Nov. Mag., in press; G. J. Ferreira, H. J. P. Freire, J. Carlos Egues, submitted.

  7. Photonic Hypercrystals

    NASA Astrophysics Data System (ADS)

    Narimanov, Evgenii E.

    2014-10-01

    We introduce a new "universality class" of artificial optical media—photonic hypercrystals. These hyperbolic metamaterials, with periodic spatial variation of dielectric permittivity on subwavelength scale, combine the features of optical metamaterials and photonic crystals. In particular, surface waves supported by a hypercrystal possess the properties of both the optical Tamm states in photonic crystals and surface-plasmon polaritons at the metal-dielectric interface.

  8. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  9. Microfabricated Optical Cavities and Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Lončar, Marko; Scherer, Axel

    Microfabricated periodic structures with a high refractive index contrast have recently become very interesting geometries for the manipulation of light. The existence of a photonic bandgap, a frequency range within which propagation of light is prevented in all directions, is very useful where spatial localization of light is required. Ideally, by constructing three-dimensional confinement geometries, light propagation can be controlled in all three dimensions. However, since the fabrication of 3D photonic crystals is difficult, a more manufacturable approach is based on the use of one- or two-dimensional geometries. Here we describe the evolution of microcavities from 1D Bragg reflectors to 2D photonic crystals. The 1D microcavity laser (VCSEL) has already found widespread commercial use in data communications, and the equivalent 2D geometry has recently attracted a lot of research attention. 2D photonic crystal lasers, fabricated within a thin dielectric membrane and perforated with a two-dimensional lattice of holes, are very appealing for dense integration of photonic devices in telecommunications and optical sensing systems. In this chapter, we describe theory and experiments of planar photonic crystals as well as their applications towards lasers and super-dispersive elements. Low-threshold 2D photonic crystal lasers were recently demonstrated both in air and in different chemical solutions and can now be used to perform spectroscopic tests on ultra-small volumes of analyte.

  10. Dual wire welding torch and method

    DOEpatents

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  11. Topological photon

    NASA Astrophysics Data System (ADS)

    Tiwari, S. C.

    2008-03-01

    We associate intrinsic energy equal to hν /2 with the spin angular momentum of photon, and propose a topological model based on orbifold in space and tifold in time as topological obstructions. The model is substantiated using vector wavefield disclinations. The physical photon is suggested to be a particlelike topological photon and a propagating wave such that the energy hν of photon is equally divided between spin energy and translational energy, corresponding to linear momentum of hν /c. The enigma of wave-particle duality finds natural resolution, and the proposed model gives new insights into the phenomena of interference and emission of radiation.

  12. Measurement of the geometric parameters of power contact wire based on binocular stereovision

    NASA Astrophysics Data System (ADS)

    Pan, Xue-Tao; Zhang, Ya-feng; Meng, Fei

    2010-10-01

    In the electrified railway power supply system, electric locomotive obtains power from the catenary's wire through the pantograph. Under the action of the pantograph, combined with various factors such as vibration, touch current, relative sliding speed, load, etc, the contact wire will produce mechanical wear and electrical wear. Thus, in electrified railway construction and daily operations, the geometric parameters such as line height, pull value, the width of wear surface must be under real-timely and non-contact detection. On the one hand, the safe operation of electric railways will be guaranteed; on the other hand, the wire endurance will be extended, and operating costs reduced. Based on the characteristics of the worn wires' image signal, the binocular stereo vision technology was applied for measurement of contact wire geometry parameters, a mathematical model of measurement of geometric parameters was derived, and the boundaries of the wound wire abrasion-point value were extracted by means of sub-pixel edge detection method based on the LOG operator with the least-squares fitting, thus measurements of the wire geometry parameters were realized. Principles were demonstrated through simulation experiments, and the experimental results show that the detection methods presented in this paper for measuring the accuracy, efficiency and convenience, etc. are close to or superior to the traditional measurements, which has laid a good foundation for the measurement system of geometric parameters for the contact wire of the development of binocular vision.

  13. Manually Operated Welding Wire Feeder

    NASA Technical Reports Server (NTRS)

    Rybicki, Daniel J. (Inventor)

    2001-01-01

    A manual welding wire feeder apparatus comprising a bendable elongate metal frame with a feed roller mounted at the center thereof for rotation about an axis transverse to the longitudinal axis of the frame. The frame ends are turned up as tabs and each provided with openings in alignment with each other and the mid-width center of the roller surface. The tab openings are sized to accommodate welding wire and each extends to a side edge of the tab, both opening on the same side of the frame, whereby welding wire can be side-loaded onto the frame. On the side of the frame, opposite the roller a lock ring handle is attached tangentially and is rotatable about the attachment point and an axis perpendicular to the frame. The device is grasped in the hand normally used to hold the wire. A finger is placed through the loop ring and the frame positioned across the palm and lower fingers. The thumb is positioned atop the wire so it can be moved from the back of the frame across the roller, and towards the front. In doing so, the wire is advanced at a steady rate in axial alignment with the tab openings and roller. To accommodate different wire diameters the frame is bendable about its center in the plane of the frame axis and wire so as to keep the wire in sufficient tension against the roller and to keep the wire fixed when the frame is tilted and thumb pressure released.

  14. Component lead wire strain relief for random vibration environments

    NASA Astrophysics Data System (ADS)

    Scardina, V. M.

    Printed circuit boards exposed to severe random vibration environments for prolonged periods often experience fatigue failures. The failures occur in connection with severed circuit traces, fractured solder joints, fretting corrosion of connector contact pins, or broken lead wires on electronic components. The present investigation is mainly concerned with the latter cause of failure. Aspects of lead wire geometry are defined and factors contributing to the development of bending stress in the lead wires are examined. Such factors are related to environmental load applications, board-specific characteristics, and component-specific characteristics. Attention is given to effects of component location, questions concerning the selection of the proper strain relief, the effects of lead length on stresses, the proper component orientation, and the characteristics of different types of components. A sample problem is also discussed.

  15. Metering Wheel-Wire Track Wire Boom Deployment Mechanism

    NASA Technical Reports Server (NTRS)

    Granoff, Mark S.

    2014-01-01

    The NASA MMS Spin Plane Double Probe (SDP) Deployer utilizes a helical path, rotating Metering Wheel and a spring loaded Wire "Holding" Track to pay out a "fixed end" 57 meter x 1.5 mm diameter Wire Boom stored between concentric storage cylinders. Unlike rotating spool type storage devices, the storage cylinders remain stationary, and the boom wire is uncoiled along the length of the cylinder via the rotation of the Metering Wheel. This uncoiling action avoids the need for slip-ring contacts since the ends of the wire can remain stationary. Conventional fixed electrical connectors (Micro-D type) are used to terminate to operational electronics.

  16. Photonic curvilinear data processing

    NASA Astrophysics Data System (ADS)

    Browning, Clyde; Quaglio, Thomas; Figueiro, Thiago; Pauliac, Sébastien; Belledent, Jérôme; Fay, Aurélien; Bustos, Jessy; Marusic, Jean-Christophe; Schiavone, Patrick

    2014-10-01

    With more and more photonic data presence in e-beam lithography, the need for efficient and accurate data fracturing is required to meet acceptable manufacturing cycle time. Large photonic based layouts now create high shot count patterns for VSB based tools. Multiple angles, sweeping curves, and non-orthogonal data create a challenge for today's e-beam tools that are more efficient on Manhattan style data. This paper describes techniques developed and used for creating fractured data for VSB based pattern generators. Proximity Effect Correction is also applied during the fracture process, taking into account variable shot sizes to apply for accuracy and design style. Choosing different fracture routines for pattern data on-the-fly allows for fast and efficient processing. Data interpretation is essential for processing curvilinear data as to its size, angle, and complexity. Fracturing complex angled data into "efficient" shot counts is no longer practical as shot creation now requires knowledge of the actual data content as seen in photonic based pattern data. Simulation and physical printing results prove the implementations for accuracy and write times compared to traditional VSB writing strategies on photonic data. Geometry tolerance is used as part of the fracturing algorithm for controlling edge placement accuracy and tuning to different e-beam processing parameters.

  17. The Drag of Streamline Wires

    NASA Technical Reports Server (NTRS)

    Jacobs, Eastman N

    1933-01-01

    Preliminary results are given of drag tests of streamline wires. Full-size wires were tested over a wide range of speeds in the N.A.C.A. high speed tunnel. The results are thus directly applicable to full-scale problems and include any compressibility effects encountered at the higher speeds. The results show how protuberances may be employed on conventional streamline wires to reduce the drag, and also show how the conventional wires compare with others having sections more like strut or symmetrical airfoil sections. Because the new wire sections developed are markedly superior aerodynamically to conventional wires, it is recommended that some of them be tested in service in order to investigate their relative susceptibility to vibration and to fatigue failure.

  18. The photon

    NASA Astrophysics Data System (ADS)

    Collins, Russell L.

    2009-10-01

    There are no TEM waves, only photons. Lets build a photon, using a radio antenna. A short antenna (2L<< λ) simplifies the calculation, letting B fall off everywhere as 1/r^2. The Biot-Savart law finds B = (μ0/4π)(LI0/r^2)θφt. The magnetic flux thru a semi-circle of radius λ/2 is set equal to the flux quantum h/e, determining the needed source strength, LI0. From this, one can integrate the magnetic energy density over a sphere of radius λ/2 and finds it to be 1.0121 hc/λ. Pretty close. A B field collapses when the current ceases, but the photon evades this by creating a ɛ0E / t displacement current at center that fully supports the toroidal B assembly as it moves at c. This E=vxB arises because the photon moves at c. Stopped, a photon decays. At every point along the photon's path, an observer will note a transient oscillation of an E field. This sources the EM ``guiding wave'', carrying little or no energy and expanding at c. At the head of the photon, all these spherical guiding waves gather ``in-phase'' as a planar wavefront. This model speaks to all the many things we know about light. The photon is tiny, but its guiding wave is huge.

  19. Geometry and Erdkinder.

    ERIC Educational Resources Information Center

    McDonald, Nathaniel J.

    2001-01-01

    Chronicles a teacher's first year teaching geometry at the Hershey Montessori Farm School in Huntsburg, Ohio. Instructional methods relied on Euclid primary readings and combined pure abstract logic with practical applications of geometry on the land. The course included geometry background imparted by Montessori elementary materials as well as…

  20. Geometry and Erdkinder.

    ERIC Educational Resources Information Center

    McDonald, Nathaniel J.

    2001-01-01

    Chronicles a teacher's first year teaching geometry at the Hershey Montessori Farm School in Huntsburg, Ohio. Instructional methods relied on Euclid primary readings and combined pure abstract logic with practical applications of geometry on the land. The course included geometry background imparted by Montessori elementary materials as well as…

  1. Development and Characterization of Intermediate-Band Quantum Wire Solar Cells

    NASA Astrophysics Data System (ADS)

    Furrow, Colin S.

    The effects of a quantum wire intermediate band, grown by molecular beam epitaxy, on the optical and electrical properties of solar cells are reported. To investigate the behavior of the intermediate band, the quantum wires were remotely doped at three different doping concentrations, the number of quantum wire layers was varied from three to twenty, and the solar cell structure was optimized. For all the structures, current-voltage and external quantum efficiency measurements were performed to examine the effect of absorption and power conversion of the intermediate band solar cell (IBSC). Time-resolved photoluminescence measurements showed that ?-doping can increase the lifetime of the excited electrons in the quantum wires. The quantum efficiency measurements revealed that the quantum wires extend the absorption spectrum in the infrared and produce a photocurrent by absorption of photons with energies below the GaAs band gap energy. In addition, the quantum wire intermediate band solar cell increased the solar conversion efficiency by 13.3% over the reference cell. An increase in the quantum efficiency was observed by increasing the number of quantum wire layers in the intermediate band. Furthermore, by optimizing the solar cell structure, the quantum efficiency and solar power conversion efficiency were substantially improved. Finally, temperature dependent current-voltage measurements reveal that the quantum wire intermediate band does not degrade the temperature sensitivity of the device. This research shows the potential for a quantum wire intermediate band as a viable option for creating higher efficiency solar cell devices.

  2. Magnetism of iron: from the bulk to the monatomic wire

    NASA Astrophysics Data System (ADS)

    Autès, Gabriel; Barreteau, Cyrille; Spanjaard, Daniel; Desjonquères, Marie-Catherine

    2006-07-01

    The magnetic properties of iron (spin and orbital magnetic moments, magnetocrystalline anisotropy energy) in various geometries and dimensionalities are investigated by using a parametrized tight-binding model in an s, p and d atomic orbital basis set including spin polarization and the effect of spin-orbit coupling. The validity of this model is well established by comparing the results with those obtained by using an ab initio code. This model is applied to the study of iron in bulk bcc and fcc phases, (110) and (001) surfaces and the monatomic wire, at several interatomic distances. New results are derived. In the case of surfaces the variation of the component of the orbital magnetic moment on the spin quantization axis has been studied as a function of depth, revealing a significant enhancement in the first two layers, especially for the (001) surface. It is found that the magnetic anisotropy energy is drastically increased in the wire and can reach several meV. This is also true for the orbital moment, which in addition is highly anisotropic. Furthermore, it is shown that when the spin quantization axis is neither parallel nor perpendicular to the wire the average orbital moment is not aligned with the spin quantization axis. At equilibrium distance the easy magnetization axis is along the wire but switches to the perpendicular direction under compression. The success of this model opens up the possibility of obtaining accurate results on other elements and systems with much more complex geometries.

  3. Topological photonics: an observation of Landau levels for optical photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Sommer, Ariel; Simon, Jonathan

    We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. This work was supported by DOE, DARPA, and AFOSR.

  4. Texture development in Galfenol wire

    NASA Astrophysics Data System (ADS)

    Boesenberg, A. J.; Restorff, J. B.; Wun-Fogle, M.; Sailsbury, H.; Summers, E.

    2013-05-01

    Galfenol (Fe-Ga alloy) wire fabrication provides a low cost alternative to directional solidification methods. This work evaluates the compositional dependence of the wire drawing suitability of Fe-Ga and characterizes the microstructural and magnetic properties of these wires. Wire has been produced with Ga contents between 10 at. % and 17 at. % to allow determination of the ductile to brittle transition (DTBT) in wire manufacture. Published results on chill cast bend specimens indicated that a DTBT occurs at roughly 15 at. % Ga. This DTBT was observed under tensile loading with a corresponding change in fracture behavior from transverse fracture to intergranular fracture. For improved magnetostrictive performance, higher Ga contents are desired, closer to the 17 at. % Ga evaluated in this work. Electron backscattered diffraction B-H loop and resonance measurements as a function of magnetic field (to determine modulus and coupling factor) are presented for as-drawn, furnace, and direct current (DC) annealed wire. Galfenol wire produced via traditional drawing methods is found to have a strong <110> (α) texture parallel to the drawing direction. As-drawn wire was observed to have a lower magnetic permeability and larger hysteresis than DC annealed wire. This is attributed to the presence of a large volume of crystalline defects; such as vacancies and dislocations.

  5. Subminiature Hot-Wire Probes

    NASA Technical Reports Server (NTRS)

    Westphal, R. V.; Lemos, F. R.; Ligrani, P. M.

    1989-01-01

    Class of improved subminiature hot-wire flow-measuring probes developed. Smaller sizes yield improved resolution in measurements of practical aerodynamic flows. Probe made in one-wire, two-perpendicular-wire, and three-perpendicular-wire version for measurement of one, two, or all three components of flow. Oriented and positioned on micromanipulator stage and viewed under microscope during fabrication. Tested by taking measurements in constant-pressure turbulent boundary layer. New probes give improved measurements of turbulence quantities near surfaces and anisotropies of flows strongly influence relative errors caused by phenomena related to spatial resolution.

  6. Plasma Formation Around Single Wires

    NASA Astrophysics Data System (ADS)

    Duselis, Peter U.; Kusse, Bruce R.

    2002-12-01

    At Cornell's Laboratory of Plasma Studies, single wires of various metals were exploded using a ˜250 ns pulser with a rise time of ˜20 A/ns. It was found that the wires first experience a resistive heating phase that lasts 50-80 ns before a rapid collapse of voltage. From that point on, the voltage across the wire was negligible while the current through the wire continued to increase. We attribute this voltage collapse to the formation of plasma about the wire. Further confirmation of this explanation will be presented along with new experimental data describing preliminary spectroscopy results, the expansion rate of the plasma, and current flow along the wire as a function of radius. The resistance of the wire-electrode connection will be shown to significantly affect the energy deposition. Various diagnostics were used to obtain these experiments. Ultraviolet sensitive vacuum photodiodes and a framing camera with an 8 ns shutter were used to detect and measure the width of the visible light emitted by the plasma. A special wire holder was constructed that allowed the transfer of current from the wire to the surrounding plasma to be observed.

  7. Plated wire memory subsystem

    NASA Technical Reports Server (NTRS)

    Carpenter, K. H.

    1974-01-01

    The design, construction, and test history of a 4096 word by 18 bit random access NDRO Plated Wire Memory for use in conjunction with a spacecraft input/output and central processing unit is reported. A technical and functional description is given along with diagrams illustrating layout and systems operation. Test data is shown on the procedures and results of system level and memory stack testing, and hybrid circuit screening. A comparison of the most significant physical and performance characteristics of the memory unit versus the specified requirements is also included.

  8. 46 CFR 111.60-11 - Wire.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be...

  9. 46 CFR 111.60-11 - Wire.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be...

  10. 46 CFR 111.60-11 - Wire.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be...

  11. 46 CFR 111.60-11 - Wire.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be...

  12. 46 CFR 111.60-11 - Wire.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be...

  13. 49 CFR 234.231 - Fouling wires.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Fouling wires. 234.231 Section 234.231..., Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway... single duplex wire with single plug acting as fouling wires is prohibited. Existing installations having...

  14. 49 CFR 234.231 - Fouling wires.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Fouling wires. 234.231 Section 234.231..., Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway... single duplex wire with single plug acting as fouling wires is prohibited. Existing installations having...

  15. A process for low cost wire grid polarizers

    NASA Astrophysics Data System (ADS)

    Watts, M. P. C.; Little, M.; Egan, E.; Hochbaum, A.; Johns, C.; Stephansen, S.

    2013-03-01

    Oblique angle metal deposition has been combined with high aspect ratio imprinted structures to create wire grid polarizers (WGP's) for use as polarization recyclers in liquid crystal displays. The process of oblique deposition was simulated to determine optimal feature profile and deposition geometry. The optical results for the oblique deposition WGP show contrast comparable to a conventionally etched WGP. The next steps to the fabrication of meter sized WGP are proposed.

  16. Production of wires and coils from high-temperature superconducting materials

    NASA Astrophysics Data System (ADS)

    Lanagan, M. T.; Balachandran, U.; Cao, M. T.; Dorris, S. E.; Dusek, J. T.; Goretta, K. C.; Poeppel, R. B.; Singh, J. P.; Youngdahl, C. A.

    1989-04-01

    Coils of high T sub c superconductors, which are essential for the development of highly efficient motors and generators, have been fabricated by plastic extrusion. Wires have been extruded in long continuous lengths, wrapped into coils, and subsequently sintered. Coils, 2 cm in diameter and comprising up to 30 turns, have been made with critical current densities of about 200 A/sq cm at 77 K. Critical current density has been found to be dependent on both sintered density and wire geometry.

  17. Final report on development of Pulse Arrested Spark Discharge (PASD) for aging aircraft wiring application

    SciTech Connect

    Lockner, Thomas Ramsbeck; Howard, R. Kevin; Pena, Gary Edward; Schneider, Larry X.; Higgins, Matthew B.; Glover, Steven Frank

    2006-09-01

    Pulsed Arrested Spark Discharge (PASD) is a Sandia National Laboratories Patented, non-destructive wiring system diagnostic that has been developed to detect defects in aging wiring systems in the commercial aircraft fleet. PASD was previously demonstrated on relatively controlled geometry wiring such as coaxial cables and shielded twisted-pair wiring through a contract with the U.S. navy and is discussed in a Sandia National Laboratories report, SAND2001-3225 ''Pulsed Arrested Spark Discharge (PASD) Diagnostic Technique for the Location of Defects in Aging Wiring Systems''. This report describes an expansion of earlier work by applying the PASD technique to unshielded twisted-pair and discrete wire configurations commonly found in commercial aircraft. This wiring is characterized by higher impedances as well as relatively non-uniform impedance profiles that have been found to be challenging for existing aircraft wiring diagnostics. Under a three year contract let by the Federal Aviation Administration, Interagency Agreement DTFA-03-00X90019, this technology was further developed for application on aging commercial aircraft wiring systems. This report describes results of the FAA program with discussion of previous work conducted under U.S. Department of Defense funding.

  18. Quantum coherence of mesoscopic stadia and wires coupled to the environment

    NASA Astrophysics Data System (ADS)

    Xie, Yuantao; Heremans, J. J.; Priol, C. Le; Vijeyaragunathan, S.; Mishima, T. D.; Santos, M. B.

    Quantum phase coherence was measured in quasi-1D wires and in mesoscopic stadia connected to wide sample regions by wire-like necks, to investigate the effects of environmental and interdevice coupling on decoherence as contrasted to intrinsic materials properties. Measurements of quantum phase coherence lengths used weak-antilocalization on nanolithographic InGaAs/InAlAs structures at 390 mK. For quantum wires, experiments show that longer wire lengths result in longer phase coherence lengths. The result is understood from the observation that longer wires average out decoherence introduced at the end sections by environmental coupling. For stadia with quantum-wire-like necks, stadium-wire coupling dominates decoherence in the stadia, rather than environmental coupling. Stadia with wider and shorter necks show longer phase coherence lengths. The result is understood from the observation that wider and shorter wires are geometrically similar to stadia, implying a stronger wave function hybridization between stadia and connecting necks and thus weaker decoherence from stadium-wire coupling. The work shows that geometry has to be taken into account in measured mesoscopic coherence. Supported by DOE DE-FG02-08ER46532 and NSF DMR-1207537.

  19. Corrosion of Wires on Wooden Wire-Bound Packaging Crates

    Treesearch

    Samuel L. Zelinka; Stan Lebow

    2015-01-01

    Wire-bound packaging crates are used by the US Army to transport materials. Because these crates may be exposed to harsh environments, they are dip-treated with a wood preservative (biocide treatment). For many years, zinc-naphthenate was the most commonly used preservative for these packaging crates and few corrosion problems with the wires were observed. Recently,...

  20. Two-Wire to Four-Wire Audio Converter

    NASA Technical Reports Server (NTRS)

    Talley, G. L., Jr; Seale, B. L.

    1983-01-01

    Simple circuit provides interface between normally incompatible voicecommunication lines. Circuit maintains 40 dB of isolation between input and output halves of four-wire line permitting two-wire line to be connected. Balancing potentiometer, Rg, adjusts gain of IC2 to null feed through from input to output. Adjustment is done on workbench just after assembly.

  1. Photonic Landau levels on cones

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-05-01

    We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids.

  2. Scalable Nernst thermoelectric power using a coiled galfenol wire

    NASA Astrophysics Data System (ADS)

    Yang, Zihao; Codecido, Emilio A.; Marquez, Jason; Zheng, Yuanhua; Heremans, Joseph P.; Myers, Roberto C.

    2017-09-01

    The Nernst thermopower usually is considered far too weak in most metals for waste heat recovery. However, its transverse orientation gives it an advantage over the Seebeck effect on non-flat surfaces. Here, we experimentally demonstrate the scalable generation of a Nernst voltage in an air-cooled metal wire coiled around a hot cylinder. In this geometry, a radial temperature gradient generates an azimuthal electric field in the coil. A Galfenol (Fe0.85Ga0.15) wire is wrapped around a cartridge heater, and the voltage drop across the wire is measured as a function of axial magnetic field. As expected, the Nernst voltage scales linearly with the length of the wire. Based on heat conduction and fluid dynamic equations, finite-element method is used to calculate the temperature gradient across the Galfenol wire and determine the Nernst coefficient. A giant Nernst coefficient of -2.6 μV/KT at room temperature is estimated, in agreement with measurements on bulk Galfenol. We expect that the giant Nernst effect in Galfenol arises from its magnetostriction, presumably through enhanced magnon-phonon coupling. Our results demonstrate the feasibility of a transverse thermoelectric generator capable of scalable output power from non-flat heat sources.

  3. Improved superconducting magnet wire

    DOEpatents

    Schuller, I.K.; Ketterson, J.B.

    1983-08-16

    This invention is directed to a superconducting tape or wire composed of alternating layers of copper and a niobium-containing superconductor such as niobium of NbTi, Nb/sub 3/Sn or Nb/sub 3/Ge. In general, each layer of the niobium-containing superconductor has a thickness in the range of about 0.05 to 1.5 times its coherence length (which for Nb/sub 3/Si is 41 A) with each copper layer having a thickness in the range of about 170 to 600 A. With the use of very thin layers of the niobium composition having a thickness within the desired range, the critical field (H/sub c/) may be increased by factors of 2 to 4. Also, the thin layers of the superconductor permit the resulting tape or wire to exhibit suitable ductility for winding on a magnet core. These compositions are also characterized by relatively high values of critical temperature and therefore will exhibit a combination of useful properties as superconductors.

  4. Soft magnetic wires

    NASA Astrophysics Data System (ADS)

    Vázquez, M.

    2001-06-01

    An overview of the present state of the art on the preparation techniques, outstanding magnetic properties and applications of soft magnetic micro and nanowires is presented. Rapid solidification techniques (in-rotating-water quenching and drawing methods) to fabricate amorphous microwires with diameter in the range from 100 down to 1 μm are first described. Electrodeposition is also employed to prepare composite microtubes (magnetic coatings) and to fill porous membranes (diameter of the order of 0.1 μm). Magnetic behaviours of interest are related to the different hysteresis loops of samples: square-shaped loops typical of bistable behaviour, and nearly non-hysteretic loop with well-defined transverse anisotropy field. The role played by magnetic dipolar interactions in the magnetic behaviour of arrays of micro and nanowires is described. A particular analysis is done on the giant magnetoimpedance (GMI) effect in the radio and microwave frequency ranges exhibited by ultrasoft microwires. Finally, a few examples of applications are introduced for magnetostrictive and non-magnetostrictive wires, they are: “magnetoelastic pens”, micromotors; DC current-sensors based on GMI, and sharpened amorphous wire tips in spin polarised scanning tunneling microscopy.

  5. Coupled atomic wires in a synthetic magnetic field

    NASA Astrophysics Data System (ADS)

    Budich, J. C.; Elben, A.; ŁÄ cki, M.; Sterdyniak, A.; Baranov, M. A.; Zoller, P.

    2017-04-01

    We propose and study systems of coupled atomic wires in a perpendicular synthetic magnetic field as a platform to realize exotic phases of quantum matter. This includes (fractional) quantum Hall states in arrays of many wires inspired by the pioneering work [C. L. Kane et al., Phys. Rev. Lett. 88, 036401 (2002), 10.1103/PhysRevLett.88.036401], as well as Meissner phases and vortex phases in double wires. With one continuous and one discrete spatial dimension, the proposed setup naturally complements recently realized discrete counterparts, i.e., the Harper-Hofstadter model and the two-leg flux ladder, respectively. We present both an in-depth theoretical study and a detailed experimental proposal to make the unique properties of the semicontinuous Harper-Hofstadter model accessible with cold-atom experiments. For the minimal setup of a double wire, we explore how a subwavelength spacing of the wires can be implemented. This construction increases the relevant energy scales by at least an order of magnitude compared to ordinary optical lattices, thus rendering subtle many-body phenomena such as Lifshitz transitions in Fermi gases observable in an experimentally realistic parameter regime. For arrays of many wires, we discuss the emergence of Chern bands with readily tunable flatness of the dispersion and show how fractional quantum Hall states can be stabilized in such systems. Using for the creation of optical potentials Laguerre-Gauss beams that carry orbital angular momentum, we detail how the coupled atomic wire setups can be realized in nonplanar geometries such as cylinders, disks, and tori.

  6. Initial investigations into the damping characteristics of wire rope vibration isolators

    NASA Technical Reports Server (NTRS)

    Cutchins, M. A.; Cochran, J. E., Jr.; Kumar, K.; Fitz-Coy, N. G.; Tinker, M. L.

    1987-01-01

    Passive dampers composed of coils of multi-strand wire rope are investigated. Analytical results range from those produced by complex NASTRAN models to those of a Coulomb damping model with variable friction force. The latter agrees well with experiment. The Coulomb model is also utilized to generate hysteresis loops. Various other models related to early experimental investigations are described. Significant closed-form static solutions for physical properties of single-and multi-strand wire ropes are developed for certain specific geometries and loading conditions. NASTRAN models concentrate on model generation and mode shapes of 2-strand and 7-strand straight wire ropes with interfacial forces.

  7. Nanoparticle Ag-enhanced textured-powder Bi-2212/Ag wire technology

    NASA Astrophysics Data System (ADS)

    Kellams, J. N.; McIntyre, P.; Pogue, N.; Vandergrifft, J.

    2015-12-01

    A new approach to the preparation of cores for Bi-2212/Ag wire is being developed. Nanoparticle Ag is homogeneously dispersed in Bi-2212 fine powder, and the mixture is uniaxially compressed to form highly textured, cold-sintered core rods. The rods can be assembled in a silver matrix, drawn to form multifilament wire, and restacked and drawn to form multifilament wire. Preliminary studies using tablet geometry demonstrate that a nonmelt heat treatment produces densification, grain growth, intergrowth among grains, and macroscopic current transport. The status of the development is reported.

  8. The Current in a Wire

    ERIC Educational Resources Information Center

    Thompson, Keith

    2009-01-01

    This little problem arose because I was frustrated with the standard electromagnetism texts, which show the magnetic field due to a current-bearing wire outside the wire [proportional to] 1/r and inside [proportional to] r. However, they never point out that the moving electrons must be influenced by the magnetic field created by the other moving…

  9. Aircraft wiring program status report

    NASA Technical Reports Server (NTRS)

    Beach, Rex

    1995-01-01

    In this Naval Air Warfare Center (NAWC) Aircraft Division status report, the general and wire and cable component activities, the systems engineering activities, the aircraft wiring lead maintenance activities, the NAVAIR/NASA interface activities, and the Base Realignment and Closure (BRAC) Commission recommendations are presented.

  10. Aircraft wiring program status report

    NASA Astrophysics Data System (ADS)

    Beach, Rex

    1995-11-01

    In this Naval Air Warfare Center (NAWC) Aircraft Division status report, the general and wire and cable component activities, the systems engineering activities, the aircraft wiring lead maintenance activities, the NAVAIR/NASA interface activities, and the Base Realignment and Closure (BRAC) Commission recommendations are presented.

  11. Wire and Packing Tape Sandwiches

    ERIC Educational Resources Information Center

    Rabinowitz, Sandy

    2009-01-01

    In this article, the author describes how students can combine craft wire with clear packing tape to create a two-dimensional design that can be bent and twisted to create a three-dimensional form. Students sandwich wire designs between two layers of tape. (Contains 1 online resource.)

  12. Wire and Packing Tape Sandwiches

    ERIC Educational Resources Information Center

    Rabinowitz, Sandy

    2009-01-01

    In this article, the author describes how students can combine craft wire with clear packing tape to create a two-dimensional design that can be bent and twisted to create a three-dimensional form. Students sandwich wire designs between two layers of tape. (Contains 1 online resource.)

  13. The Current in a Wire

    ERIC Educational Resources Information Center

    Thompson, Keith

    2009-01-01

    This little problem arose because I was frustrated with the standard electromagnetism texts, which show the magnetic field due to a current-bearing wire outside the wire [proportional to] 1/r and inside [proportional to] r. However, they never point out that the moving electrons must be influenced by the magnetic field created by the other moving…

  14. Preradiation studies for non-thermal Z-pinch wire load experiments on Saturn

    SciTech Connect

    Sanford, T.W.L.; Humphreys, D.R.; Poukey, J.W.; Marder, B.M.; Halbleib, J.A.; Crow, J.T.; Spielman, R.B.; Mock, R.C.

    1994-06-01

    The implosion dynamics of compact wire arrays on Saturn are explored as a function of wire mass m, wire length {ell}, wire radii R, and radial power-flow feed geometry using the ZORK code. Electron losses and the likelihood of arcing in the radial feed adjacent the wire load are analyzed using the TWOQUICK and CYLTRAN codes. The physical characteristics of the implosion and subsequent thermal radiation production are estimated using the LASNEX code in one dimension. These analyses show that compact tungsten wire arrays with parameters suggested by D. Mosher and with a 21-nH vacuum feed geometry satisfy the empirical scaling criterion I/(M/{ell}) {approximately} 2 MA/(mg/cm) of Mosher for optimizing non-thermal radiation from z pinches, generate low electron losses in the radial feeds, and generate electric fields at the insulator stack below the Charlie Martin flashover limit thereby permitting full power to be delivered to the load. Under such conditions, peak currents of {approximately}5 MA can be delivered to wire loads {approximately}20 ns before the driving voltage reverses at the insulator stack, potentially allowing the m = 0 instability to develop with the subsequent emission of non-thermal radiation as predicted by the Mosher model.

  15. Torque transmission between square wire and bracket as a function of measurement, form and hardness parameters.

    PubMed

    Fischer-Brandies, H; Orthuber, W; Es-Souni, M; Meyer, S

    2000-01-01

    The aim of the study was to investigate the influence of cross section, edge geometry and structural hardness on torque transmission between square wire and bracket. For this purpose, 5 different brands of stainless steel square wire in 3 dimensions (0.016" x 0.016", 0.016" x 0.022" and 0.017" x 0.025") were inserted into edgewise brackets with a slot size of 0.018" and loaded with different torques (1 and 3 Ncm). The slot and wire geometries were analyzed by computer on ground specimens before and after loading. In addition, the Vickers hardness and micro-hardness of the unstressed and stressed metal surfaces were determined. While the slot size was very accurately maintained, the wire dimensions deviated downwards by an average of 10%. Torque transmission led to notching and bending-up phenomena on the bracket slot flanks. A torque loading of 3 Ncm increased the torque play of 0.016" x 0.022" wires by 3.6 degrees, and of 0.017" x 0.025" wires by 3.7 degrees. In the case of 0.016" x 0.016" wires, an effective torque transmission was no longer possible. The average Vickers hardness of the wires was 533 kp/mm2, and that of the brackets 145 kp/mm2. The micro-hardness in the deformation area of stressed internal slot walls increased with increasing load transmission from 204 to 338 kp/mm2. As a result of excessively small wire dimensions and plastic deformation of the brackets, a relatively large torque play occurs. Deformation and notching in the area of the internal slot walls are inconsistent with demands for recycling brackets. A standardization of bracket wire systems stating the actual torque play would be desirable.

  16. Forming Refractory Insulation On Copper Wire

    NASA Technical Reports Server (NTRS)

    Setlock, J.; Roberts, G.

    1995-01-01

    Alternative insulating process forms flexible coat of uncured refractory insulating material on copper wire. Coated wire formed into coil or other complex shape. Wire-coating apparatus forms "green" coat on copper wire. After wire coiled, heating converts "green" coat to refractory electrical insulator. When cured to final brittle form, insulating material withstands temperatures above melting temperature of wire. Process used to make coils for motors, solenoids, and other electrical devices to be operated at high temperatures.

  17. Electrode carrying wire for GTAW welding

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

    1990-01-01

    A welding torch for gas tungsten arc welding apparatus has a hollow tungsten electrode including a ceramic liner and forms the filler metal wire guide. The wire is fed through the tungsten electrode thereby reducing the size of the torch to eliminate clearance problems which exist with external wire guides. Since the wire is preheated from the tungsten more wire may be fed into the weld puddle, and the wire will not oxidize because it is always within the shielding gas.

  18. Forming Refractory Insulation On Copper Wire

    NASA Technical Reports Server (NTRS)

    Setlock, J.; Roberts, G.

    1995-01-01

    Alternative insulating process forms flexible coat of uncured refractory insulating material on copper wire. Coated wire formed into coil or other complex shape. Wire-coating apparatus forms "green" coat on copper wire. After wire coiled, heating converts "green" coat to refractory electrical insulator. When cured to final brittle form, insulating material withstands temperatures above melting temperature of wire. Process used to make coils for motors, solenoids, and other electrical devices to be operated at high temperatures.

  19. Internal wire guide for GTAW welding

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

    1989-01-01

    A welding torch for gas tungsten arc welding apparatus has a filler metal wire guide positioned within the torch, and within the shielding gas nozzle. The wire guide is adjacent to the tungsten electrode and has a ceramic liner through which the wire is fed. This reduces the size of the torch and eliminates the outside clearance problems that exit with external wire guides. Additionally, since the wire is always within the shielding gas, oxidizing of the wire is eliminated.

  20. Apollo experience report: Electrical wiring subsystem

    NASA Technical Reports Server (NTRS)

    White, L. D.

    1975-01-01

    The general requirements of the electrical wiring subsystems and the problem areas and solutions that occurred during the major part of the Apollo Program are detailed in this report. The concepts and definitions of specific requirements for electrical wiring; wire-connecting devices; and wire-harness fabrication, checkout, and installation techniques are discussed. The design and development of electrical wiring and wire-connecting devices are described. Mission performance is discussed, and conclusions and recommendations for future programs are presented.

  1. Wire metamaterials: physics and applications.

    PubMed

    Simovski, Constantin R; Belov, Pavel A; Atrashchenko, Alexander V; Kivshar, Yuri S

    2012-08-16

    The physics and applications of a broad class of artificial electromagnetic materials composed of lattices of aligned metal rods embedded in a dielectric matrix are reviewed. Such structures are here termed wire metamaterials. They appear in various settings and can operate from microwaves to THz and optical frequencies. An important group of these metamaterials is a wire medium possessing extreme optical anisotropy. The study of wire metamaterials has a long history, however, most of their important and useful properties have been revealed and understood only recently, especially in the THz and optical frequency ranges where the wire media correspond to the lattices of microwires and nanowires, respectively. Another group of wire metamaterials are arrays and lattices of nanorods of noble metals whose unusual properties are driven by plasmonic resonances. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Welding wire pressure sensor assembly

    NASA Technical Reports Server (NTRS)

    Morris, Timothy B. (Inventor); Milly, Peter F., Sr. (Inventor); White, J. Kevin (Inventor)

    1994-01-01

    The present invention relates to a device which is used to monitor the position of a filler wire relative to a base material being welded as the filler wire is added to a welding pool. The device is applicable to automated welding systems wherein nonconsumable electrode arc welding processes are utilized in conjunction with a filler wire which is added to a weld pool created by the electrode arc. The invention senses pressure deviations from a predetermined pressure between the filler wire and the base material, and provides electrical signals responsive to the deviations for actuating control mechanisms in an automatic welding apparatus so as to minimize the pressure deviation and to prevent disengagement of the contact between the filler wire and the base material.

  3. Tungsten wire for incandescent lamps

    SciTech Connect

    Walter, J.L.; Briant, C.L. )

    1990-09-01

    Tungsten wire for incandescent lamp filaments must operate at high temperatures and for long times. To meet these requirements, the grain morphology of the wire must be controlled to reduce the propensity for grain boundary sliding. The morphology is a function of the distribution of very small pockets of potassium in the wire and the mechanical processing from ingot to wire. The behavior of the filament is directly related to the grain morphology. This paper describes the mechanism by which the potassium is incorporated into and distributed in the ingot. The elongation and spheroidization of the bubbles during hot rolling and swaging is also examined and related to the grain morphology of wire. Some indications of the relationship between grain morphology and filament behavior are also given.

  4. Photon generator

    DOEpatents

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  5. Photon diffraction

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2009-11-01

    In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/˜scjh/.

  6. Photonic lanterns

    NASA Astrophysics Data System (ADS)

    Leon-Saval, Sergio G.; Argyros, Alexander; Bland-Hawthorn, Joss

    2013-12-01

    Multimode optical fibers have been primarily (and almost solely) used as "light pipes" in short distance telecommunications and in remote and astronomical spectroscopy. The modal properties of the multimode waveguides are rarely exploited and mostly discussed in the context of guiding light. Until recently, most photonic applications in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astrophotonics and space photonics. Interestingly, these devices are now being explored for use in telecommunications and are likely to find commercial use in the next few years, particularly in the development of compact spectrographs. Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail. Furthermore, we foreshadow future applications of this technology to the field of nanophotonics.

  7. Single-photon detection, truth, and misinterpretation

    NASA Astrophysics Data System (ADS)

    Berloffa, E. H.

    2013-10-01

    Within this investigation it is critically questioned, if we really can detect "single photons", respectively the response of a single quantum transition by use of modern photon detectors. In the course it is shown that avalanche photodiodes (AVDs) especially in the "Geiger" mode by virtue of its geometry (effective area) indeed can detect "single photon" events as proclaimed by the manufacturers, but they tacitly assume the bandwidth of originating visible source being not greater than ~ 2.107 [Hz]. A short excurse to solid state basic physics makes it obvious applying the adequate doping accomplishes "single photon detection". Nevertheless this does not mean there is a 1:1 correspondence between a photon emanated from the source location and that detected within the detector module. Propagation characteristics were simply overlooked during the numerous discussions about "single photon" detection. Practical examples are worked out on hand of a pin- / and a AVDphotodiode.

  8. Sintered wire cathode

    DOEpatents

    Falce, Louis R.; Ives, R. Lawrence

    2009-06-09

    A porous cathode structure is fabricated from a plurality of wires which are placed in proximity to each other in elevated temperature and pressure for a sintering time. The sintering process produces the porous cathode structure which may be divided into a plurality of individual porous cathodes, one of which may be placed into a dispenser cathode support which includes a cavity for containing a work function reduction material such as BaO, CaO, and Al.sub.2O.sub.3. The work function reduction material migrates through the pores of the porous cathode from a work replenishment surface adjacent to the cavity of the dispenser cathode support to an emitting cathode surface, thereby providing a dispenser cathode which has a uniform work function and therefore a uniform electron emission.

  9. Generation of Fourier-transform-limited heralded single photons

    SciTech Connect

    U'Ren, Alfred B.; Jeronimo-Moreno, Yasser; Garcia-Gracia, Hipolito

    2007-02-15

    In this paper we study the spectral (temporal) properties of heralded single photon wave packets, triggered by the detection of an idler photon in the process of parametric down conversion. The generated single photons are studied within the framework of the chronocyclic Wigner function, from which the single photon spectral width and temporal duration can be computed. We derive specific conditions on the two-photon joint spectral amplitude which result in both pure and Fourier-transform-limited heralded single photons. Likewise, we present specific source geometries which lead to the fulfillment of these conditions and show that one of these geometries leads, for a given pump bandwidth, to the temporally shortest possible heralded single photon wave packets.

  10. Developments in special geometry

    NASA Astrophysics Data System (ADS)

    Mohaupt, Thomas; Vaughan, Owen

    2012-02-01

    We review the special geometry of Script N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.

  11. Imaging nanowire plasmon modes with two-photon polymerization

    SciTech Connect

    Gruber, Christian; Trügler, Andreas; Hohenester, Ulrich; Ditlbacher, Harald; Hohenau, Andreas; Krenn, Joachim R.; Hirzer, Andreas; Schmidt, Volker

    2015-02-23

    Metal nanowires sustain propagating surface plasmons that are strongly confined to the wire surface. Plasmon reflection at the wire end faces and interference lead to standing plasmon modes. We demonstrate that these modes can be imaged via two-photon (plasmon) polymerization of a thin film resist covering the wires and subsequent electron microscopy. Thereby, the plasmon wavelength and the phase shift of the nanowire mode picked up upon reflection can be directly retrieved. In general terms, polymerization imaging is a promising tool for the imaging of propagating plasmon modes from the nano- to micro-scale.

  12. Photonic Molecule Lasers Revisited

    NASA Astrophysics Data System (ADS)

    Gagnon, Denis; Dumont, Joey; Déziel, Jean-Luc; Dubé, Louis J.

    2014-05-01

    Photonic molecules (PMs) formed by coupling two or more optical resonators are ideal candidates for the fabrication of integrated microlasers, photonic molecule lasers. Whereas most calculations on PM lasers have been based on cold-cavity (passive) modes, i.e. quasi-bound states, a recently formulated steady-state ab initio laser theory (SALT) offers the possibility to take into account the spectral properties of the underlying gain transition, its position and linewidth, as well as incorporating an arbitrary pump profile. We will combine two theoretical approaches to characterize the lasing properties of PM lasers: for two-dimensional systems, the generalized Lorenz-Mie theory will obtain the resonant modes of the coupled molecules in an active medium described by SALT. Not only is then the theoretical description more complete, the use of an active medium provides additional parameters to control, engineer and harness the lasing properties of PM lasers for ultra-low threshold and directional single-mode emission. We will extend our recent study and present new results for a number of promising geometries. The authors acknowledge financial support from NSERC (Canada) and the CERC in Photonic Innovations of Y. Messaddeq.

  13. Integrated photonic quantum walks

    NASA Astrophysics Data System (ADS)

    Gräfe, Markus; Heilmann, René; Lebugle, Maxime; Guzman-Silva, Diego; Perez-Leija, Armando; Szameit, Alexander

    2016-10-01

    Over the last 20 years quantum walks (QWs) have gained increasing interest in the field of quantum information science and processing. In contrast to classical walkers, quantum objects exhibit intrinsic properties like non-locality and non-classical many-particle correlations, which renders QWs a versatile tool for quantum simulation and computation as well as for a deeper understanding of genuine quantum mechanics. Since they are highly controllable and hardly interact with their environment, photons seem to be ideally suited quantum walkers. In order to study and exploit photonic QWs, lattice structures that allow low loss coherent evolution of quantum states are demanded. Such requirements are perfectly met by integrated optical waveguide devices that additionally allow a substantial miniaturization of experimental settings. Moreover, by utilizing the femtosecond direct laser writing technique three-dimensional waveguide structures are capable of analyzing QWs also on higher dimensional geometries. In this context, advances and findings of photonic QWs are discussed in this review. Various concepts and experimental results are presented covering, such as different quantum transport regimes, the Boson sampling problem, and the discrete fractional quantum Fourier transform.

  14. SABRINA: an interactive three-dimensional geometry-mnodeling program for MCNP

    SciTech Connect

    West, J.T. III

    1986-10-01

    SABRINA is a fully interactive three-dimensional geometry-modeling program for MCNP, a Los Alamos Monte Carlo code for neutron and photon transport. In SABRINA, a user constructs either body geometry or surface geometry models and debugs spatial descriptions for the resulting objects. This enhanced capability significantly reduces effort in constructing and debugging complicated three-dimensional geometry models for Monte Carlo analysis. 2 refs., 33 figs.

  15. Plasma chemistry in wire chambers

    SciTech Connect

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

  16. Dual exposure, two-photon, conformal phasemask lithography for three dimensional silicon inverse woodpile photonic crystals

    SciTech Connect

    Shir, Daniel J.; Nelson, Erik C.; Chanda, Debashis; Brzezinski, Andrew; Braun, Paul V.; Rogers, John A.; Wiltzius, Pierre

    2010-01-01

    The authors describe the fabrication and characterization of three dimensional silicon inverse woodpile photonic crystals. A dual exposure, two-photon, conformal phasemask technique is used to create high quality polymer woodpile structures over large areas with geometries that quantitatively match expectations based on optical simulations. Depositing silicon into these templates followed by the removal of the polymer results in silicon inverse woodpile photonic crystals for which calculations indicate a wide, complete photonic bandgap over a range of structural fill fractions. Spectroscopic measurements of normal incidence reflection from both the polymer and siliconphotonic crystals reveal good optical properties.

  17. Control Methods for Wire Arrangement Unit of New Multi-Wire Saw

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Qian, Juying; Cai, Ji-Fei; Wang, Yan

    To solve such problems as unstable wire transmission caused by overly dense or overlaid local wire arrangement, an electronic cam wire arrangement method is put forward in this paper, adopting servo motor to drive the cam, making the wire arrangement motor follow the speed change of taking-up motor, outputing the wire arrangement motor speed with the deduced functional operation relation, and controlling the wire arrangement pulley to evenly distribute the steel wire on the taking-up roller.

  18. Influence of geometry on liquid oxygen magnetohydrodynamics

    SciTech Connect

    Boulware, Jeffrey C.; Ban, Heng; Jensen, Scott; Wassom, Steve

    2010-11-15

    Magnetic fluid actuators have performed well in industrial applications, but have a limited temperature range due to the freezing point of the carrier fluid. Liquid oxygen (LOX) presents a pure, paramagnetic fluid suitable for use in a cryogenic magnetic fluid system; therefore, it is a potential solution to increasing the thermal range of magnetic fluid technology without the need for magnetic particles. The current study presents experimental work regarding the influence of geometry on the dynamics of a LOX slug in a 1.9 mm quartz tube when pulsed by a solenoid in a closed volume. A numerical analysis calculated the optimal solenoid geometry and balanced the magnetic, damping, and pressure forces to determine optimal slug lengths. Three configurations comprised the experiment: (1) a 24-gauge wire solenoid with an optimized 2.7 cm length slug, (2) a 30-gauge wire solenoid with an optimized 1.3 cm length slug, and (3) a 30-gauge wire solenoid with a nonoptimized 2.5 cm length slug. Typically, the hydrodynamic breakdown limit is calculated and used to determine the system range; however the experiment showed that the hydrodynamic breakdown limit was never reached by the slug. This implied that, instead, the system range should factor in a probabilistic risk of failure calculated as a function of the induced pressure change from its oscillations. The experimental data were also used to establish a nondimensional relationship between the maximum displacement and initial magnetic pressure on the slug. The average initial velocity of the slug was found to be proportional to the initial magnetic pressure, Mason number, and slug length. The results of this study can be used in the design and optimization of a LOX fluid system for space or low-temperature applications. (author)

  19. Spatial filtering with photonic crystals

    SciTech Connect

    Maigyte, Lina; Staliunas, Kestutis

    2015-03-15

    Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

  20. The Beauty of Geometry

    ERIC Educational Resources Information Center

    Morris, Barbara H.

    2004-01-01

    This article describes a geometry project that used the beauty of stained-glass-window designs to teach middle school students about geometric figures and concepts. Three honors prealgebra teachers and a middle school mathematics gifted intervention specialist created a geometry project that covered the curriculum and also assessed students'…

  1. Twistors to twisted geometries

    SciTech Connect

    Freidel, Laurent; Speziale, Simone

    2010-10-15

    In a previous paper we showed that the phase space of loop quantum gravity on a fixed graph can be parametrized in terms of twisted geometries, quantities describing the intrinsic and extrinsic discrete geometry of a cellular decomposition dual to the graph. Here we unravel the origin of the phase space from a geometric interpretation of twistors.

  2. Geometry + Technology = Proof

    ERIC Educational Resources Information Center

    Lyublinskaya, Irina; Funsch, Dan

    2012-01-01

    Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

  3. Euclidean Geometry via Programming.

    ERIC Educational Resources Information Center

    Filimonov, Rossen; Kreith, Kurt

    1992-01-01

    Describes the Plane Geometry System computer software developed at the Educational Computer Systems laboratory in Sofia, Bulgaria. The system enables students to use the concept of "algorithm" to correspond to the process of "deductive proof" in the development of plane geometry. Provides an example of the software's capability…

  4. Geometry of multihadron production

    SciTech Connect

    Bjorken, J.D.

    1994-10-01

    This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions.

  5. Geometry + Technology = Proof

    ERIC Educational Resources Information Center

    Lyublinskaya, Irina; Funsch, Dan

    2012-01-01

    Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

  6. Square and round Bi(2 2 2 3) wire configurations and their AC losses

    NASA Astrophysics Data System (ADS)

    Su, Xiaodong; Witz, Grégoire; Passerini, Reynald; Kwasnitza, K.; Flükiger, René

    2002-08-01

    In order to reduce the effect of field anisotropy, but also in view of future cabling facilities, a series of Bi(2 2 2 3) wires with various square and round configurations were prepared using a combination of two-axial rolling and drawing. As previously reported, two-axis rolling of a wire configuration, with filaments being perpendicular or inclined to each other, cannot lead to an optimized rolling texture for both directions, e.g. parallel and perpendicular to the tape surface: it gives an average. As a result, even using the same precursor powders, the values of Jc in wire configurations are inherently lower than those obtained on standard powder-in-tube tapes. SEM images show that particular care has to be taken in order to avoid a distorted alignment of the filaments in certain local areas. The influence of local stresses on the filaments and their influence on the final texture were studied systematically. The critical current measurements as a function of magnetic field showed that wires with the filament configuration with a rotation symmetry exhibit the most angle-insensitive behavior of Jc( B). Due to the wire configuration, the expected relatively low Jc values, 11 kA/cm 2 at 77 K and zero field, were measured for square wires. AC loss measurements were performed in wires with various configurations and with twist pitches down to 2 mm. The results show that both wire geometry and twisting have a positive effect on the AC losses.

  7. Requirements for Printed Wiring Boards

    NASA Technical Reports Server (NTRS)

    1984-01-01

    In order to maintain the high standards of the NASA printed wiring programs, this publication: prescribes NASA's requirements for assuring reliable rigid printed wiring boards; describes and incorporates basic considerations necessary to assure reliable rigid printed wiring boards; establishes the supplier's responsibility to train and certify personnel; provides for supplier documentation of the fabrication and inspection procedures to be used for NASA work, including supplier innovations and changes in technology; and provides visual workmanship standards to aid those responsible for determining quality conformance to the established requirements.

  8. HTS Wire: status and prospects

    NASA Astrophysics Data System (ADS)

    Malozemoff, A. P.; Verebelyi, D. T.; Fleshler, S.; Aized, D.; Yu, D.

    2003-04-01

    Practical, robust high temperature superconducting (HTS) wire is a composite of high temperature superconductor and metal. The composite provides many advantages, including improved mechanical properties and stability. Multi-filamentary composite fabricated with the BSCCO HTS material has achieved performance for commercial applications, and commercial price/performance is on the near horizon. This wire enables HTS applications such as power cables, marine propulsion motors, utility generators and magnets for materials processing. Coated conductor is also a composite, combining the YBCO HTS material with a metal or metal-alloy substrate; this technology is in the stage of research and development. The status and commercial prospects of these wire technologies are reviewed.

  9. Butterfly wing color: A photonic crystal demonstration

    NASA Astrophysics Data System (ADS)

    Proietti Zaccaria, Remo

    2016-01-01

    We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

  10. Diamond Wire Saw for Precision Machining of Laser Target Components

    SciTech Connect

    Bono, M J; Bennett, D W

    2005-08-08

    The fabrication of precision laser targets requires a wide variety of specialized mesoscale manufacturing techniques. The diamond wire saw developed in this study provides the capability to precisely section meso-scale workpieces mounted on the assembly stations used by the Target Fabrication Group. This new capability greatly simplifies the fabrication of many types of targets and reduces the time and cost required to build the targets. A variety of materials are used to fabricate targets, including metals, plastics with custom designed chemical formulas, and aerogels of various densities. The materials are usually provided in the form of small pieces or cast rods that must be machined to the required shape. Many of these materials, such as metals and some plastics, can be trimmed using a parting tool on a diamond turning machine. However, other materials, such as aerogels and brittle materials, cannot be adequately cut with a parting tool. In addition, the geometry of the parts often requires that the workpieces be held in a special assembly station, which excludes the use of a parting tool. In the past, these materials were sectioned using a small, handheld coping saw that used a diamond-impregnated wire as a blade. This miniature coping saw was effective, but it required several hours to cut through certain materials. Furthermore, the saw was guided by hand and often caused significant damage to fragile aerogels. To solve these problems, the diamond wire saw shown in Figure 1 was developed. The diamond wire saw is designed to machine through materials that are mounted in the Target Fabrication Group's benchtop assembly stations. These assembly stations are the primary means of aligning and assembling target components, and there is often a need to machine materials while they are mounted in the assembly stations. Unfortunately, commercially available saws are designed for very different applications and are far too large to be used with the assembly stations

  11. Evaluating Thermally Damaged Polyimide Insulated Wiring (MIL-W-81381) with Ultrasound

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.; Anastasi, Robert F.

    2002-01-01

    A series of experiments to investigate the use of ultrasound for measuring wire insulation have been conducted. Initial laboratory tests were performed on MIL-W-81381/7,/12, and /21 aviation wire, a wire that has polyimide (Kapton Registered Trademark) layers for insulation. Samples of this wiring were exposed to 370C temperatures for different periods of time to induce a range of thermal damage. For each exposure, 12 samples of each gauge (12, 16, and 20 gauges) were processed. The velocity of the lowest order axisymmetric ultrasonic guided mode, a mode that is sensitive to the geometry and stiffness of the wire conductor and insulation, was measured. The phase velocity for the 20-gauge MIL-W-81381/7 wire had a baseline value of 3023 +/- 78 m/s. After exposure to the high temperatures, the wire's phase velocity rapidly increased, and reached an asymptotic value of 3598 +/- 20 m/s after 100 hours exposure. Similar behavior was measured for the 16 gauge MIL-W-81381/21 wire and 12 gauge MIL-W-81381/12 wire which had baseline values of 3225 +/- 22 m/s and 3403 +/- 33 m/s respectively, and reached asymptotic values of 3668 +/- 19 m/s, and 3679 +/- 42 m/s respectively. These measured velocity changes represent changes of 19, 14, and 8 percent respectively for the 20, 16, and 12 gauge wires. Finally, some results for a wire with an ethylene tetrafluoroethylene insulation are reported. Qualitatively similar behaviors are noted ultrasonically.

  12. Influence of Flaws of Wire Rod Surface, Inclusions and Voids on Wire Breaks in Superfine Wire Drawing

    NASA Astrophysics Data System (ADS)

    Yoshida, Kazunari; Norasethasopon, Somchai; Shinohara, Tetsuo; Ido, Ryuta

    By means of the finite element analysis (FEA), this study analyzed wire breaks that occurred in the drawing fine wires containing flaws on the wire surface, inclusion and void. The deformation behavior of an inclusion was examined, in which the inclusion's location is assumed to be on the center axis of the wire, and the cause of wire breaks and their prevention method were clarified. It was found that an inclusion diameter/wire diameter ratio of 0.4 or higher increases the likelihood of wire breaks occurring. When the inclusion is not assumed to be in the center axis of the wire, it was also found that necking and wire breaks appear more frequently. FEA showed that a flaw grows with each processing step, when a small circumferential flaw is placed on the wire rod surface, and eventually becomes a surface defect, which is called a check mark in practice.

  13. Larger sized wire arrays on 1.5 MA Z-pinch generator

    SciTech Connect

    Safronova, A. S. Kantsyrev, V. L. Weller, M. E. Shlyaptseva, V. V. Shrestha, I. K. Esaulov, A. A. Stafford, A.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

    2014-12-15

    Experiments on the UNR Zebra generator with Load Current Multiplier (LCM) allow for implosions of larger sized wire array loads than at standard current of 1 MA. Advantages of larger sized planar wire array implosions include enhanced energy coupling to plasmas, better diagnostic access to observable plasma regions, and more complex geometries of the wire loads. The experiments with larger sized wire arrays were performed on 1.5 MA Zebra with LCM (the anode-cathode gap was 1 cm, which is half the gap used in the standard mode). In particular, larger sized multi-planar wire arrays had two outer wire planes from mid-atomic-number wires to create a global magnetic field (gmf) and plasma flow between them. A modified central plane with a few Al wires at the edges was put in the middle between outer planes to influence gmf and to create Al plasma flow in the perpendicular direction (to the outer arrays plasma flow). Such modified plane has different number of empty slots: it was increased from 6 up to 10, hence increasing the gap inside the middle plane from 4.9 to 7.7 mm, respectively. Such load configuration allows for more independent study of the flows of L-shell mid-atomic-number plasma (between the outer planes) and K-shell Al plasma (which first fills the gap between the edge wires along the middle plane) and their radiation in space and time. We demonstrate that such configuration produces higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions and how the load geometry (size of the gap in the middle plane) influences K-shell Al radiation. In particular, K-shell Al radiation was delayed compared to L-shell mid-atomic-number radiation when the gap in the middle plane was large enough (when the number of empty slots was increased up to ten)

  14. Green photonics

    NASA Astrophysics Data System (ADS)

    Quan, Frederic

    2012-02-01

    Photonics, the broad merger of electronics with the optical sciences, encompasses such a wide swath of technology that its impact is almost universal in our everyday lives. This is a broad overview of some aspects of the industry and their contribution to the ‘green’ or environmental movement. The rationale for energy conservation is briefly discussed and the impact of photonics on our everyday lives and certain industries is described. Some opinions from industry are presented along with market estimates. References are provided to some of the most recent research in these areas.

  15. Vesicle Photonics

    SciTech Connect

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  16. Near-infrared characterization of gallium nitride photonic-crystal waveguides and cavities.

    PubMed

    Dharanipathy, U; Vico Triviño, N; Yan, C; Diao, Z; Carlin, J-F; Grandjean, N; Houdré, R

    2012-11-15

    We report the design and optical characterization of fully suspended wire waveguides and photonic crystal (PhC) membranes fabricated on a gallium nitride layer grown on silicon substrate operating at 1.5 μm. W1-type PhC waveguides are coupled with suspended wires and are investigated using a standard end-fire setup. The experimental and theoretical dispersion properties of the propagating modes in the wires and photonic-crystal waveguides are shown. Modified L3 cavities with quality factors of up to 2200 and heterostructure cavities with quality factors of up to 5400 are experimentally demonstrated.

  17. A Dynamic Analysis of the Parallel-Plate EMP (Electromagnetic Pulse) Simulator Using a Wire Mesh Approximation and the Numerical Electromagnetics Code.

    DTIC Science & Technology

    1987-09-01

    realized that there is a definite tradeoff to this configuration due to the introduction of a sharp bend in the thin-wire geometry. In Section 2.1 it was...CHAPTER 4 (’()\\CLLDING REMARKS ?o develop the characteristics of a paralel -plt , 4 i~ ~ ~ . 1,’nc ,: !jior by scattering theory, using d thin-wire inc,,1

  18. 29 CFR 1919.79 - Wire rope.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same...

  19. 29 CFR 1919.79 - Wire rope.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same...

  20. 29 CFR 1919.79 - Wire rope.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same...

  1. 29 CFR 1919.79 - Wire rope.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same...

  2. 29 CFR 1919.79 - Wire rope.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same...

  3. Spring control of wire harness loops

    NASA Technical Reports Server (NTRS)

    Curcio, P. J.

    1979-01-01

    Negator spring control guides wire harness between movable and fixed structure. It prevents electrical wire harness loop from jamming or being severed as wire moves in response to changes in position of aircraft rudder. Spring-loaded coiled cable controls wire loop regardless of rudder movement.

  4. Photonic Bandgaps in Photonic Molecules

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok; Gates, Amanda L.; Fuller, Kirk A.; Gregory, Don A.; Witherow, William K.; Paley, Mark S.; Frazier, Donald O.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    This talk will focus on photonic bandgaps that arise due to nearly free photon and tight-binding effects in coupled microparticle and ring-resonator systems. The Mie formulation for homogeneous spheres is generalized to handle core/shell systems and multiple concentric layers in a manner that exploits an analogy with stratified planar systems, thereby allowing concentric multi-layered structures to be treated as photonic bandgap (PBG) materials. Representative results from a Mie code employing this analogy demonstrate that photonic bands arising from nearly free photon effects are easily observed in the backscattering, asymmetry parameter, and albedo for periodic quarter-wave concentric layers, though are not readily apparent in extinction spectra. Rather, the periodicity simply alters the scattering profile, enhancing the ratio of backscattering to forward scattering inside the bandgap, in direct analogy with planar quarter-wave multilayers. PBGs arising from tight-binding may also be observed when the layers (or rings) are designed such that the coupling between them is weak. We demonstrate that for a structure consisting of N coupled micro-resonators, the morphology dependent resonances split into N higher-Q modes, in direct analogy with other types of oscillators, and that this splitting ultimately results in PBGs which can lead to enhanced nonlinear optical effects.

  5. Demonstrating Forces between Parallel Wires.

    ERIC Educational Resources Information Center

    Baker, Blane

    2000-01-01

    Describes a physics demonstration that dramatically illustrates the mutual repulsion (attraction) between parallel conductors using insulated copper wire, wooden dowels, a high direct current power supply, electrical tape, and an overhead projector. (WRM)

  6. Wire Jewelry/Black History.

    ERIC Educational Resources Information Center

    Daniel, Robert A.; Robinson, Charles C.

    1984-01-01

    Described is a project which made the study of Black history more real to fifth graders by having them make wire jewelry, smaller versions of the ornate filigreed ironwork produced by slave blacksmiths. (RM)

  7. Dieless wire drawing with lasers

    NASA Astrophysics Data System (ADS)

    Liedl, G.; Schuöcker, D.

    2007-06-01

    Thin wires are produced by drawing through nozzle-like tools, so called dies, that suffer from strong wear due to friction. In order to avoid the latter disadvantage the dies can be replaced by a laser beam heating the wire to such extend that the yield strength becomes smaller than the tensile strength and thus the wire is elongated and consequently constricted. To avoid rupture, the wire is cooled down again after the desired reduction of the diameter is reached. A further important advantage of this new process is that only one drawing step with a laser can substitute a large number of mechanical drawing actions, thus making the process much more efficient. Theoretical considerations and experimental investigations prove the feasibility of the latter new laser process and are subject to a description in the actual paper.

  8. Demonstrating Forces between Parallel Wires.

    ERIC Educational Resources Information Center

    Baker, Blane

    2000-01-01

    Describes a physics demonstration that dramatically illustrates the mutual repulsion (attraction) between parallel conductors using insulated copper wire, wooden dowels, a high direct current power supply, electrical tape, and an overhead projector. (WRM)

  9. Aircraft geometry verification with enhanced computer generated displays

    NASA Technical Reports Server (NTRS)

    Cozzolongo, J. V.

    1982-01-01

    A method for visual verification of aerodynamic geometries using computer generated, color shaded images is described. The mathematical models representing aircraft geometries are created for use in theoretical aerodynamic analyses and in computer aided manufacturing. The aerodynamic shapes are defined using parametric bi-cubic splined patches. This mathematical representation is then used as input to an algorithm that generates a color shaded image of the geometry. A discussion of the techniques used in the mathematical representation of the geometry and in the rendering of the color shaded display is presented. The results include examples of color shaded displays, which are contrasted with wire frame type displays. The examples also show the use of mapped surface pressures in terms of color shaded images of V/STOL fighter/attack aircraft and advanced turboprop aircraft.

  10. Aircraft geometry verification with enhanced computer-generated displays

    NASA Technical Reports Server (NTRS)

    Cozzolongo, J. V.

    1982-01-01

    A method for visual verification of aerodynamic geometries using computer-generated, color-shaded images is described. The mathematical models representing aircraft geometries are created for use in theoretical aerodynamic analyses and in computer-aided manufacturing. The aerodynamic shapes are defined using parametric bi-cubic splined patches. This mathematical representation is then used as input to an algorithm that generates a color-shaded image of the geometry. A discussion of the techniques used in the mathematical representation of the geometry and in the rendering of the color-shaded display is presented. The results include examples of color-shaded displays, which are contrasted with wire-frame-type displays. The examples also show the use of mapped surface pressures in terms of color-shaded images of V/STOL fighter/attack aircraft and advanced turboprop aircraft.

  11. Modeling birds on wires.

    PubMed

    Aydoğdu, A; Frasca, P; D'Apice, C; Manzo, R; Thornton, J M; Gachomo, B; Wilson, T; Cheung, B; Tariq, U; Saidel, W; Piccoli, B

    2017-02-21

    In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group. We compare the results from the model with experimental data, derived from the analysis of pictures of pigeons and starlings taken in New Jersey: two different image elaboration protocols allow us to establish a good agreement with the model and to quantify its main parameters. We also discuss the potential handedness of the birds, by analyzing the group organization features and the group dynamics at the arrival of new birds. Finally, we propose a more refined mathematical model that describes landing and departing birds by suitable stochastic processes.

  12. Mechanical properties and fracture strength of cathodically polarized prestressing wire

    SciTech Connect

    Kiszowski, S.; Hartt, W.H.

    1996-11-01

    Constant extension rate testing experiments were performed upon prestressing steel wire specimens prepared from three lots of Grade 270 and one lot of Grade 250 material for the purpose of characterizing susceptibility to environmental cracking under conditions associated with cathodic protection of prestressed concrete components and structures. Smooth, notched (six different geometries) and pitted (four different geometries) specimens were tested in air and deaerated saturated Ca(OH){sub 2}-distilled water at potentials of {minus}0.90 and {minus}1.30 v (SCE) and strength and ductility properties characterized. Relatively low strength was recorded for steel specimens at {minus}09.90 v from material for which the weight percent chromium was relatively high (0.24 w/o compared to 0.02 w/o). Under conditions that are likely to be most relevant to service, fracture load correlated with the amount by which the local wire cross section area was reduced, either from a notch or pit, and was independent of depth of the irregularity and of root radius to the extent to which these were addressed. It was concluded that it may be unsafe to apply cathodically protection to prestressing wire, even in situations where potential is maintained in the regime where hydrogen embrittlement should not occur.

  13. 49 CFR 234.241 - Protection of insulated wire; splice in underground wire.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Protection of insulated wire; splice in underground wire. 234.241 Section 234.241 Transportation Other Regulations Relating to Transportation... of insulated wire; splice in underground wire. Insulated wire shall be protected from mechanical...

  14. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

  15. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits,...

  16. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits,...

  17. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits,...

  18. 49 CFR 234.241 - Protection of insulated wire; splice in underground wire.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Protection of insulated wire; splice in underground wire. 234.241 Section 234.241 Transportation Other Regulations Relating to Transportation... of insulated wire; splice in underground wire. Insulated wire shall be protected from...

  19. Method of manufacturing superconductor wire

    DOEpatents

    Motowidlo, Leszek

    2014-09-16

    A method for forming Nb.sub.3Sn superconducting wire is provided. The method employs a powder-in-tube process using a high-tin intermetallic compound, such as MnSn.sub.2, for producing the Nb.sub.3Sn. The use of a high-tin intermetallic compound enables the process to perform hot extrusion without melting the high-tin intermetallic compound. Alternatively, the method may entail drawing the wire without hot extrusion.

  20. Smart Wire Grid: Resisting Expectations

    ScienceCinema

    Ramsay, Stewart; Lowe, DeJim

    2016-07-12

    Smart Wire Grid's DSR technology (Discrete Series Reactor) can be quickly deployed on electrical transmission lines to create intelligent mesh networks capable of quickly rerouting electricity to get power where and when it's needed the most. With their recent ARPA-E funding, Smart Wire Grid has been able to move from prototype and field testing to building out a US manufacturing operation in just under a year.

  1. Brake-By-Wire Program

    DTIC Science & Technology

    2006-05-31

    SUPPLEMENTARY NOTES Report contains color. 14. ABSTRACT Two design iterations for electric calipers and two systems (full brake by wire and hybrid brakes ...were developed for use on a ground vehicle. The program demonstrated a fully integrated electric caliper and full brake -by-wire system on a sports...release. Project Context The development of an electric brake caliper and associated systems for automotive application represented a significant

  2. Smart Wire Grid: Resisting Expectations

    SciTech Connect

    Ramsay, Stewart; Lowe, DeJim

    2014-03-03

    Smart Wire Grid's DSR technology (Discrete Series Reactor) can be quickly deployed on electrical transmission lines to create intelligent mesh networks capable of quickly rerouting electricity to get power where and when it's needed the most. With their recent ARPA-E funding, Smart Wire Grid has been able to move from prototype and field testing to building out a US manufacturing operation in just under a year.

  3. 1 mil gold bond wire study.

    SciTech Connect

    Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.; Rutherford, Brian Milne

    2013-05-01

    In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, the gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.

  4. HTS Wire Development Workshop: Proceedings

    SciTech Connect

    Not Available

    1994-07-01

    The 1994 High-Temperature Superconducting Wire Development Workshop was held on February 16--17 at the St. Petersburg Hilton and Towers in St. Petersburg, Florida. The meeting was hosted by Florida Power Corporation and sponsored by the US Department of Energy`s Superconductivity Program for Electric Power Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. The meeting opened with a general discussion on the needs and benefits of superconductivity from a utility perspective, the US global competitiveness position, and an outlook on the overall prospects of wire development. The meeting then focused on four important technology areas: Wire characterization: issues and needs; technology for overcoming barriers: weak links and flux pinning; manufacturing issues for long wire lengths; and physical properties of HTS coils. Following in-depth presentations, working groups were formed in each technology area to discuss the most important current research and development issues. The working groups identified research areas that have the potential for greatly enhancing the wire development effort. These areas are discussed in the summary reports from each of the working groups. This document is a compilation of the workshop proceedings including all general session presentations and summary reports from the working groups.

  5. Laser soldering of enameled wires

    NASA Astrophysics Data System (ADS)

    Böhm, S.; Hemken, G.; Noack, K.

    2009-02-01

    In electrical connections with enameled copper wires, isolation material residue can be found in the solder area when the coating is not stripped. This residue can lead to mechanical and electrical problems. In electronic devices and MEMS, quality requirements increase with rising thermal requirements for electrical contacts made from enameled copper wire. Examples for this exist in the area of automotive electronics, consumer electronics and in the field of machine design. Typical products with electrical connecting which use enameled wires include: micro-phones and speakers (especially for mobile phones), coil forms, small transformers, relays, clock coils, and so on. Due to increasing thermal and electrical requirements, the manufacturer of enameled wires continuously develops new isolating materials for the improvement of isolation classes, thermal resistance, etc. When using current bonding and solder processes, there exist problems for contacting enameled copper wire with these insulation layers. Therefore the Institute of Joining and Welding, Department Micro Joining developed a laser based solder process with which enamels copper wires can enable high quality electrical connections without a preceding stripping process.

  6. Variable geometry trusses

    NASA Technical Reports Server (NTRS)

    Robertshaw, H. H.; Reinholtz, C. F.

    1989-01-01

    Vibration control and kinematic control with variable-geometry trusses are covered. The analytical approach taken is to model each actuator with lumped masses and model a beam with finite elements, including in each model the generalized reaction forces from the beam on the actuator or vice versa. It is concluded that, from an operational standpoint, the variable-geometry truss actuator is more favorable than the inertia-type actuator. A spatial variable-geometry truss is used to test out rudimentary robotic tasks.

  7. Connecting to Thermocouples with Fewer Lead Wires

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2003-01-01

    A simple technique has been devised to reduce the number of lead wires needed to connect an array of thermocouples to the instruments (e.g., voltmeters) used to read their output voltages. Because thermocouple wires are usually made of expensive metal alloys, reducing the number of lead wires can effect a considerable reduction in the cost of such an array. Reducing the number of wires also reduces the number of terminals and the amount of space needed to accommodate the wires.

  8. Fabrication of Pd-Cr wire

    NASA Technical Reports Server (NTRS)

    Diamond, Sidney; Leach, Dennen M.

    1989-01-01

    Fabrication of Pd-13 percent Cr alloy wires is described. Melting, casting, swaging and annealing processes are discussed. Drawing to reach two diameters (0.003 inch and 0.00176 inch) of wire is described. Representative micrographs of the Pd-Cr alloy at selected stages during wire fabrication are included. The resistance of the wire was somewhat lower, by about 15 to 20 percent, than comparable wire of other alloys used for strain gages.

  9. Experimental Results for Space-Wire-D

    NASA Astrophysics Data System (ADS)

    Parkes, Steve; Gibson, David; Ferrer, Albert

    2015-09-01

    SpaceWire-D is a deterministic extension to SpaceWire that uses time-division multiplexing to schedule traffic within time-slots. It allows a single SpaceWire network to be used for both time-critical avionics control applications and asynchronous payload data-handling simultaneously using existing SpaceWire technology. In this paper we describe the services of SpaceWire-D and present experimental results for each service.

  10. Efficient way to convert propagating waves into guided waves via gradient wire structures.

    PubMed

    Chu, Hong Chen; Luo, Jie; Lai, Yun

    2016-08-01

    We propose a method for the design of gradient wire structures that are capable of converting propagating waves into guided waves along the wire. The conversion process is achieved by imposing an additional wave vector to the scattered waves via the gradient wire structure, such that the wave vector of scattered waves is beyond the wave number in the background medium. Thus, the scattered waves turn into evanescent waves. We demonstrate that two types of gradient wire structures, with either a gradient permittivity and a fixed radius, or a gradient radius and a fixed permittivity, can both be designed to realize such a wave conversion effect. The principle demonstrated in our work has potential applications in various areas including nanophotonics, silicone photonics, and plasmonics.

  11. Development of CRID (Cerenkov Ring Imaging Detector) single electron wire detector

    SciTech Connect

    Aston, D.; Bean, A.; Bienz, T.; Bird, F.; Caldwell, D.; Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Dasu, S.; Dunwoodie, W.

    1989-02-01

    We describe the R and D effort to define the design parameters, method of construction and experimental results from the single electron wire detectors. These detectors will be used for particle identification using the Cerenkov Ring Imaging techniques in the SLD experiment at SLAC. We present measurements of pulse heights for several gases as a function of gas gain, charge division performance on a single electron signal using both 7 /mu/m and 33 /mu/m diameter carbon wires, photon feedback in TMAE laden gas, average pulse shape, and its comparison with the predicted shape and cross-talk. In addition, we present results of wire aging tests, and other tests associated with construction of this unusual type of wire chamber. 12 refs., 9 figs.

  12. Assessment of SFR Wire Wrap Simulation Uncertainties

    SciTech Connect

    Delchini, Marc-Olivier G.; Popov, Emilian L.; Pointer, William David; Swiler, Laura P.

    2016-09-30

    Predictive modeling and simulation of nuclear reactor performance and fuel are challenging due to the large number of coupled physical phenomena that must be addressed. Models that will be used for design or operational decisions must be analyzed for uncertainty to ascertain impacts to safety or performance. Rigorous, structured uncertainty analyses are performed by characterizing the model’s input uncertainties and then propagating the uncertainties through the model to estimate output uncertainty. This project is part of the ongoing effort to assess modeling uncertainty in Nek5000 simulations of flow configurations relevant to the advanced reactor applications of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. Three geometries are under investigation in these preliminary assessments: a 3-D pipe, a 3-D 7-pin bundle, and a single pin from the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility. Initial efforts have focused on gaining an understanding of Nek5000 modeling options and integrating Nek5000 with Dakota. These tasks are being accomplished by demonstrating the use of Dakota to assess parametric uncertainties in a simple pipe flow problem. This problem is used to optimize performance of the uncertainty quantification strategy and to estimate computational requirements for assessments of complex geometries. A sensitivity analysis to three turbulent models was conducted for a turbulent flow in a single wire wrapped pin (THOR) geometry. Section 2 briefly describes the software tools used in this study and provides appropriate references. Section 3 presents the coupling interface between Dakota and a computational fluid dynamic (CFD) code (Nek5000 or STARCCM+), with details on the workflow, the scripts used for setting up the run, and the scripts used for post-processing the output files. In Section 4, the meshing methods used to generate the THORS and 7-pin bundle meshes are explained. Sections 5, 6 and 7 present numerical results

  13. Proof in Transformation Geometry

    ERIC Educational Resources Information Center

    Bell, A. W.

    1971-01-01

    The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

  14. What Is Geometry?

    ERIC Educational Resources Information Center

    Chern, Shiing-Shen

    1990-01-01

    Discussed are the major historical developments of geometry. Euclid, Descartes, Klein's Erlanger Program, Gaus and Riemann, globalization, topology, Elie Cartan, and an application to molecular biology are included as topics. (KR)

  15. Gingerbread-House Geometry.

    ERIC Educational Resources Information Center

    Emenaker, Charles E.

    1999-01-01

    Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)

  16. Flyby Geometry Optimization Tool

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.

    2007-01-01

    The Flyby Geometry Optimization Tool is a computer program for computing trajectories and trajectory-altering impulsive maneuvers for spacecraft used in radio relay of scientific data to Earth from an exploratory airplane flying in the atmosphere of Mars.

  17. Proof in Transformation Geometry

    ERIC Educational Resources Information Center

    Bell, A. W.

    1971-01-01

    The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

  18. What Is Geometry?

    ERIC Educational Resources Information Center

    Chern, Shiing-Shen

    1990-01-01

    Discussed are the major historical developments of geometry. Euclid, Descartes, Klein's Erlanger Program, Gaus and Riemann, globalization, topology, Elie Cartan, and an application to molecular biology are included as topics. (KR)

  19. Facilitating Understandings of Geometry.

    ERIC Educational Resources Information Center

    Pappas, Christine C.; Bush, Sara

    1989-01-01

    Illustrates some learning encounters for facilitating first graders' understanding of geometry. Describes some of children's approaches using Cuisenaire rods and teacher's intervening. Presents six problems involving various combinations of Cuisenaire rods and cubes. (YP)

  20. Gingerbread-House Geometry.

    ERIC Educational Resources Information Center

    Emenaker, Charles E.

    1999-01-01

    Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)

  1. Length dependence of electron transport through molecular wires--a first principles perspective.

    PubMed

    Khoo, Khoong Hong; Chen, Yifeng; Li, Suchun; Quek, Su Ying

    2015-01-07

    One-dimensional wires constitute a fundamental building block in nanoscale electronics. However, truly one-dimensional metallic wires do not exist due to Peierls distortion. Molecular wires come close to being stable one-dimensional wires, but are typically semiconductors, with charge transport occurring via tunneling or thermally-activated hopping. In this review, we discuss electron transport through molecular wires, from a theoretical, quantum mechanical perspective based on first principles. We focus specifically on the off-resonant tunneling regime, applicable to shorter molecular wires (<∼4-5 nm) where quantum mechanics dictates electron transport. Here, conductance decays exponentially with the wire length, with an exponential decay constant, beta, that is independent of temperature. Different levels of first principles theory are discussed, starting with the computational workhorse - density functional theory (DFT), and moving on to many-electron GW methods as well as GW-inspired DFT + Sigma calculations. These different levels of theory are applied in two major computational frameworks - complex band structure (CBS) calculations to estimate the tunneling decay constant, beta, and Landauer-Buttiker transport calculations that consider explicitly the effects of contact geometry, and compute the transmission spectra directly. In general, for the same level of theory, the Landauer-Buttiker calculations give more quantitative values of beta than the CBS calculations. However, the CBS calculations have a long history and are particularly useful for quick estimates of beta. Comparing different levels of theory, it is clear that GW and DFT + Sigma calculations give significantly improved agreement with experiment compared to DFT, especially for the conductance values. Quantitative agreement can also be obtained for the Seebeck coefficient - another independent probe of electron transport. This excellent agreement provides confirmative evidence of off

  2. Geometrical dependence of quantum decoherence in circular arenas with side-wires

    NASA Astrophysics Data System (ADS)

    Xie, Yuantao; Le Priol, Clément; Heremans, Jean J.

    2016-12-01

    Low-temperature quantum phase coherence lengths were experimentally measured in mesoscopic circular arenas fabricated on InGaAs quantum wells. The arenas are connected to wide sample regions by short side-wires, to investigate the effects of geometry in comparison to intrinsic materials properties on quantum decoherence. Universal conductance fluctuations were used to quantify the phase coherence lengths as a function of temperature and geometry. The experimental data show a dependence of phase coherence lengths on side-wire length and width-to-length ratio, which is accounted for by the competing effects of decoherence by coupling to the classical environment and Nyquist decoherence in ergodic wires. The observed decay of phase coherence lengths with the increasing temperature is consistent with expectations. The work demonstrates that geometrical effects influence the measured mesoscopic quantum decoherence.

  3. Correlated atomic wires on substrates. II. Application to Hubbard wires

    NASA Astrophysics Data System (ADS)

    Abdelwahab, Anas; Jeckelmann, Eric; Hohenadler, Martin

    2017-07-01

    In the first part of our theoretical study of correlated atomic wires on substrates, we introduced lattice models for a one-dimensional quantum wire on a three-dimensional substrate and their approximation by quasi-one-dimensional effective ladder models [Abdelwahab et al., preceding paper, Phys. Rev. B 96, 035445 (2017), 10.1103/PhysRevB.96.035445]. In this second part, we apply this approach to the case of a correlated wire with a Hubbard-type electron-electron repulsion deposited on an insulating substrate. The ground-state and spectral properties are investigated numerically using the density-matrix renormalization group method and quantum Monte Carlo simulations. As a function of the model parameters, we observe various phases with quasi-one-dimensional low-energy excitations localized in the wire, namely, paramagnetic Mott insulators, Luttinger liquids, and spin-1 /2 Heisenberg chains. The validity of the effective ladder models is assessed for selected parameters by studying the dependence of results on the number of legs and comparing to the full three-dimensional model. We find that narrow ladder models accurately reproduce the quasi-one-dimensional excitations of the full three-dimensional model but predict only qualitatively whether excitations are localized around the wire or delocalized in the three-dimensional substrate.

  4. Software Geometry in Simulations

    NASA Astrophysics Data System (ADS)

    Alion, Tyler; Viren, Brett; Junk, Tom

    2015-04-01

    The Long Baseline Neutrino Experiment (LBNE) involves many detectors. The experiment's near detector (ND) facility, may ultimately involve several detectors. The far detector (FD) will be significantly larger than any other Liquid Argon (LAr) detector yet constructed; many prototype detectors are being constructed and studied to motivate a plethora of proposed FD designs. Whether it be a constructed prototype or a proposed ND/FD design, every design must be simulated and analyzed. This presents a considerable challenge to LBNE software experts; each detector geometry must be described to the simulation software in an efficient way which allows for multiple authors to easily collaborate. Furthermore, different geometry versions must be tracked throughout their use. We present a framework called General Geometry Description (GGD), written and developed by LBNE software collaborators for managing software to generate geometries. Though GGD is flexible enough to be used by any experiment working with detectors, we present it's first use in generating Geometry Description Markup Language (GDML) files to interface with LArSoft, a framework of detector simulations, event reconstruction, and data analyses written for all LAr technology users at Fermilab. Brett is the other of the framework discussed here, the General Geometry Description (GGD).

  5. SOC and Fractal Geometry

    NASA Astrophysics Data System (ADS)

    McAteer, R. T. J.

    2013-06-01

    When Mandelbrot, the father of modern fractal geometry, made this seemingly obvious statement he was trying to show that we should move out of our comfortable Euclidean space and adopt a fractal approach to geometry. The concepts and mathematical tools of fractal geometry provides insight into natural physical systems that Euclidean tools cannot do. The benet from applying fractal geometry to studies of Self-Organized Criticality (SOC) are even greater. SOC and fractal geometry share concepts of dynamic n-body interactions, apparent non-predictability, self-similarity, and an approach to global statistics in space and time that make these two areas into naturally paired research techniques. Further, the iterative generation techniques used in both SOC models and in fractals mean they share common features and common problems. This chapter explores the strong historical connections between fractal geometry and SOC from both a mathematical and conceptual understanding, explores modern day interactions between these two topics, and discusses how this is likely to evolve into an even stronger link in the near future.

  6. Common Geometry Module

    SciTech Connect

    Tautges, Timothy J.

    2005-01-01

    The Common Geometry Module (CGM) is a code library which provides geometry functionality used for mesh generation and other applications. This functionality includes that commonly found in solid modeling engines, like geometry creation, query and modification; CGM also includes capabilities not commonly found in solid modeling engines, like geometry decomposition tools and support for shared material interfaces. CGM is built upon the ACIS solid modeling engine, but also includes geometry capability developed beside and on top of ACIS. CGM can be used as-is to provide geometry functionality for codes needing this capability. However, CGM can also be extended using derived classes in C++, allowing the geometric model to serve as the basis for other applications, for example mesh generation. CGM is supported on Sun Solaris, SGI, HP, IBM, DEC, Linux and Windows NT platforms. CGM also indudes support for loading ACIS models on parallel computers, using MPI-based communication. Future plans for CGM are to port it to different solid modeling engines, including Pro/Engineer or SolidWorks. CGM is being released into the public domain under an LGPL license; the ACIS-based engine is available to ACIS licensees on request.

  7. Photon Collider Physics with Real Photon Beams

    SciTech Connect

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  8. Plasma Expansion in the Geometry of a Collapsing Star

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Vitagliano, L.; Xue, S.-S.

    2004-10-01

    We describe the evolution of an electron-positron-photon plasma created by Sauter-Heisenberg-Euler-Schwinger mechanism around a collapsing charged star core in the Reissner-Nordströgeometry external to the core, in view of the application in the framework of the EMBH theory for gamma ray bursts.

  9. Parametrically enhanced hidden photon search

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Mardon, Jeremy; Rajendran, Surjeet; Zhao, Yue

    2014-10-01

    Many theories beyond the Standard Model contain hidden photons. A light hidden photon will generically couple to the Standard Model through a kinetic mixing term, giving a powerful avenue for detection using "light-shining-through-a-wall"-type transmission experiments with resonant cavities. We demonstrate a parametric enhancement of the signal in such experiments, resulting from transmission of the longitudinal mode of the hidden photon. While previous literature has focused on the production and detection of transverse modes, the longitudinal mode allows a significant improvement in experimental sensitivity. Although optical experiments such as ALPS are unable to take useful advantage of this enhancement, the reach of existing microwave cavity experiments such as CROWS is significantly enhanced beyond their published results. Future microwave cavity experiments, designed with appropriate geometry to take full advantage of the longitudinal mode, will provide a powerful probe of hidden-photon parameter space extending many orders of magnitude beyond current limits, including significant regions where the hidden photon can be dark matter.

  10. Brillouin light scattering from quantized spin waves in micron-size magnetic wires

    NASA Astrophysics Data System (ADS)

    Jorzick, J.; Demokritov, S. O.; Mathieu, C.; Hillebrands, B.; Bartenlian, B.; Chappert, C.; Rousseaux, F.; Slavin, A. N.

    1999-12-01

    An experimental study of spin-wave quantization in arrays of micron-size magnetic Ni80Fe20 wires by means of Brillouin light-scattering spectroscopy is reported. Dipolar-dominated Damon-Eshbach spin-wave modes laterally quantized in a single wire with quantized wave vector values determined by the width of the wire are studied. The frequency splitting between quantized modes, which decreases with increasing mode number, depends on the wire sizes and is up to 1.5 GHz. The transferred wave vector interval, where each mode is observed, is calculated using a light-scattering theory for confined geometries. The frequencies of the modes are calculated, taking into account finite-size effects. The results of the calculations are in a good agreement with the experimental data.

  11. Two-dimensional magnetohydrodynamic studies of implosion modes of nested wire array z-pinches

    SciTech Connect

    Huang, Jun; Ding, Ning Xue, Chuang; Sun, Shunkai

    2014-07-15

    Implosion dynamics of nested wire arrays in (r, θ) geometry was studied with two-dimensional magnetohydrodynamic (2D MHD) simulations. Three different implosion modes are obtained by just changing the wire number of the outer array, when the other conditions, such as the initial radius, length, mass of each array, the wire number of the inner array, and the discharge voltage waveform, are fixed. Simulation results show that the effect of discrete wires, which cannot be described by the thin shell inductive model, will influence the distribution of current between the outer and inner arrays at the early stage, and the discrepancy between results from MHD and thin shell model increases with the interwire gap of the outer array.

  12. Hydrogen sensor based on metallic photonic crystal slabs.

    PubMed

    Nau, D; Seidel, A; Orzekowsky, R B; Lee, S-H; Deb, S; Giessen, H

    2010-09-15

    We present a hydrogen sensor based on metallic photonic crystal slabs. Tungsten trioxide (WO(3)) is used as a waveguide layer below an array of gold nanowires. Hydrogen exposure influences the optical properties of this photonic crystal arrangement by gasochromic mechanisms, where the photonic crystal geometry leads to sharp spectral resonances. Measurements reveal a change of the transmission depending on the hydrogen concentration. Theoretical limits for the detection range and sensitivity of this approach are discussed.

  13. Cloud geometry effects on atmospheric solar absorption

    SciTech Connect

    Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

    2000-04-15

    A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

  14. Plasma arc torch with coaxial wire feed

    DOEpatents

    Hooper, Frederick M

    2002-01-01

    A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

  15. Microalgae photonics

    NASA Astrophysics Data System (ADS)

    Floume, Timmy; Coquil, Thomas; Sylvestre, Julien

    2011-05-01

    Due to their metabolic flexibility and fast growth rate, microscopic aquatic phototrophs like algae have a potential to become industrial photochemical converters. Algae photosynthesis could enable the large scale production of clean and renewable liquid fuels and chemicals with major environmental, economic and societal benefits. Capital and operational costs are the main issues to address through optical, process and biochemical engineering improvements. In this perspective, a variety of photonic approaches have been proposed - we introduce them here and describe their potential, limitations and compatibility with separate biotechnology and engineering progresses. We show that only sunlight-based approaches are economically realistic. One of photonics' main goals in the algae field is to dilute light to overcome photosaturation effects that impact upon cultures exposed to full sunlight. Among other approaches, we introduce a widely-compatible broadband spectral adaptation technique called AlgoSun® that uses luminescence to optimize sunlight spectrum in view of the bioconverter's requirements.

  16. Californium Recovery from Palladium Wire

    SciTech Connect

    Burns, Jon D.

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  17. Fabrication of square and round Ag/Bi(2223) wires and their ac loss behaviour

    NASA Astrophysics Data System (ADS)

    Su, X. D.; Witz, G.; Kwasnitza, K.; Flükiger, R.

    2002-08-01

    Square and round wires have been fabricated by using a combination of two-axial rolling and drawing in order to reduce the effect of field anisotropy and to confirm the decrease of ac losses predicted by calculation. Critical current measurements, as a function of magnetic field angle, confirmed that the symmetrical configuration of filaments inside the wire leads to an almost angle-insensitive behaviour of Jc(B). The Bi(2223) grains in our wires have a higher misalignment angle (around 8°) with respect to flat tapes, due to the particular wire configuration and the use of two-axial rolling. Therefore, the Jc values in our square wire are somewhat lower, 11 kA cm-2 at 77 K and zero field. AC loss measurements showed that the combination of wire geometry and twisting leads to strongly reduced ac losses in square Ag/Bi(2223) wires when compared to flat tapes: the value of 0.53 mW A-1 m-1 was measured, regardless of the field direction.

  18. Photonic homeostatics

    NASA Astrophysics Data System (ADS)

    Liu, Timon C.; Li, Fan-Hui

    2010-11-01

    Photonic homeostatics is a discipline to study the establishment, maintenance, decay, upgrading and representation of function-specific homoestasis (FSH) by using photonics. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stress may increase sirtuin 1 (SIRT1) activities above FSH-specific SIRT1 activity to induce a function far from its FSH. On the one hand, low level laser irradiation or monochromatic light (LLL) can not modulate a function in its FSH or a stress in its stress-specific homeostasis (StSH), but modulate a function far from its FSH or a stress far from its StSH. On the other hand, the biophotons from a biosystem with its function in its FSH should be less than the one from the biosystem with its function far from its FSH. The non-resonant interaction of low intensity laser irradiation or monochromatic light (LIL) and a kind of membrane protein can be amplified by all the membrane proteins if the function is far from its FSH. This amplification might hold for biophoton emission of the membrane protein so that the photonic spectroscopy can be used to represent the function far from its FSH, which is called photonomics.

  19. Integrable Background Geometries

    NASA Astrophysics Data System (ADS)

    Calderbank, David M. J.

    2014-03-01

    This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ℓ-manifold, determines a (k+ℓ)-dimensional geometry (k+ℓ≤4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ℓ-dimensional group H acting on itself by the regular representation, all (k+ℓ)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(∞) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(Σ^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently

  20. Photon Sieve Space Telescope

    NASA Astrophysics Data System (ADS)

    Andersen, G.; Dearborn, M.; Hcharg, G.

    2010-09-01

    We are investigating new technologies for creating ultra-large apertures (>20m) for space-based imagery. Our approach has been to create diffractive primaries in flat membranes deployed from compact payloads. These structures are attractive in that they are much simpler to fabricate, launch and deploy compared to conventional three-dimensional optics. In this case the flat focusing element is a photon sieve which consists of a large number of holes in an otherwise opaque substrate. A photon sieve is essentially a large number of holes located according to an underlying Fresnel Zone Plate (FZP) geometry. The advantages over the FZP are that there are no support struts which lead to diffraction spikes in the far-field and non-uniform tension which can cause wrinkling of the substrate. Furthermore, with modifications in hole size and distribution we can achieve improved resolution and contrast over conventional optics. The trade-offs in using diffractive optics are the large amounts of dispersion and decreased efficiency. We present both theoretical and experimental results from small-scale prototypes. Several key solutions to issues of limited bandwidth and efficiency have been addressed. Along with these we have studied the materials aspects in order to optimize performance and achieve a scalable solution to an on-orbit demonstrator. Our current efforts are being directed towards an on-orbit 1m solar observatory demonstration deployed from a CubeSat bus.

  1. Contact Geometry of Curves

    NASA Astrophysics Data System (ADS)

    Vassiliou, Peter J.

    2009-10-01

    Cartan's method of moving frames is briefly recalled in the context of immersed curves in the homogeneous space of a Lie group G. The contact geometry of curves in low dimensional equi-affine geometry is then made explicit. This delivers the complete set of invariant data which solves the G-equivalence problem via a straightforward procedure, and which is, in some sense a supplement to the equivariant method of Fels and Olver. Next, the contact geometry of curves in general Riemannian manifolds (M,g) is described. For the special case in which the isometries of (M,g) act transitively, it is shown that the contact geometry provides an explicit algorithmic construction of the differential invariants for curves in M. The inputs required for the construction consist only of the metric g and a parametrisation of structure group SO(n); the group action is not required and no integration is involved. To illustrate the algorithm we explicitly construct complete sets of differential invariants for curves in the Poincaré half-space H3 and in a family of constant curvature 3-metrics. It is conjectured that similar results are possible in other Cartan geometries.

  2. Geometry of membrane fission.

    PubMed

    Frolov, Vadim A; Escalada, Artur; Akimov, Sergey A; Shnyrova, Anna V

    2015-01-01

    Cellular membranes define the functional geometry of intracellular space. Formation of new membrane compartments and maintenance of complex organelles require division and disconnection of cellular membranes, a process termed membrane fission. Peripheral membrane proteins generally control membrane remodeling during fission. Local membrane stresses, reflecting molecular geometry of membrane-interacting parts of these proteins, sum up to produce the key membrane geometries of fission: the saddle-shaped neck and hour-glass hemifission intermediate. Here, we review the fundamental principles behind the translation of molecular geometry into membrane shape and topology during fission. We emphasize the central role the membrane insertion of specialized protein domains plays in orchestrating fission in vitro and in cells. We further compare individual to synergistic action of the membrane insertion during fission mediated by individual protein species, proteins complexes or membrane domains. Finally, we describe how local geometry of fission intermediates defines the functional design of the protein complexes catalyzing fission of cellular membranes. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. In situ three-dimensional reconstruction of mouse heart sympathetic innervation by two-photon excitation fluorescence imaging

    PubMed Central

    Freeman, Kim; Tao, Wen; Sun, Hongli; Soonpaa, Mark H.; Rubart, Michael

    2013-01-01

    Background Sympathetic nerve wiring in the mammalian heart has remained largely unexplored. Resolving the wiring diagram of the cardiac sympathetic network would help establish the structural underpinnings of neurocardiac coupling. New Method We used two-photon excitation fluorescence microscopy, combined with a computer-assisted 3-D tracking algorithm, to map the local sympathetic circuits in living hearts from adult transgenic mice expressing enhanced green fluorescent protein (EGFP) in peripheral adrenergic neurons. Results Quantitative co-localization analyses confirmed that the intramyocardial EGFP distribution recapitulated the anatomy of the sympathetic arbor. In the left ventricular subepicardium of the uninjured heart, the sympathetic network was composed of multiple subarbors, exhibiting variable branching and looping topology. Axonal branches did not overlap with each other within their respective parental subarbor nor with neurites of annexed subarbors. The sympathetic network in the border zone of a 2-week-old myocardial infarction was characterized by substantive rewiring, which included spatially heterogeneous loss and gain of sympathetic fibers and formation of multiple, predominately nested, axon loops of widely variable circumference and geometry. Comparison with Existing Methods In contrast to mechanical tissue sectioning methods that may involve deformation of tissue and uncertainty in registration across sections, our approach preserves continuity of structure, which allows tracing of neurites over distances, and thus enables derivation of the three-dimensional and topological morphology of cardiac sympathetic nerves. Conclusions Our assay should be of general utility to unravel the mechanisms governing sympathetic axon spacing during development and disease. PMID:24056230

  4. Total internal reflection photonic crystal prism.

    PubMed

    Schonbrun, Ethan; Abashin, Maxim; Blair, John; Wu, Qi; Park, Wounjhang; Fainman, Yeshaiahu; Summers, Christopher J

    2007-06-25

    An integrated total internal reflection prism is demonstrated that generates a transversely localized evanescent wave along the boundary between a photonic crystal and an etched out trench. The reflection can be described by either the odd symmetry of the Bloch wave or a tangential momentum matching condition. In addition, the Bloch wave propagates through the photonic crystal in a negative refraction regime, which manages diffraction within the prism. A device with three input channels has been fabricated and tested that illuminates different regions of the reflection interface. The reflected wave is then sampled by a photonic wire array, where the individual channels are resolved. Heterodyne near field scanning optical microscopy is used to characterize the spatial phase variation of the evanescent wave and its decay constant.

  5. Students Discovering Spherical Geometry Using Dynamic Geometry Software

    ERIC Educational Resources Information Center

    Guven, Bulent; Karatas, Ilhan

    2009-01-01

    Dynamic geometry software (DGS) such as Cabri and Geometers' Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to…

  6. Students Discovering Spherical Geometry Using Dynamic Geometry Software

    ERIC Educational Resources Information Center

    Guven, Bulent; Karatas, Ilhan

    2009-01-01

    Dynamic geometry software (DGS) such as Cabri and Geometers' Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to…

  7. Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode.

    PubMed

    Wu, Bulong; Luo, Xiaobing; Zheng, Huai; Liu, Sheng

    2011-11-21

    Gold wire bonding is an important packaging process of lighting emitting diode (LED). In this work, we studied the effect of gold wire bonding on the angular uniformity of correlated color temperature (CCT) in white LEDs whose phosphor layers were coated by freely dispersed coating process. Experimental study indicated that different gold wire bonding impacts the geometry of phosphor layer, and it results in different fluctuation trends of angular CCT at different spatial planes in one LED sample. It also results in various fluctuating amplitudes of angular CCT distributions at the same spatial plane for samples with different wire bonding angles. The gold wire bonding process has important impact on angular uniformity of CCT in LED package.

  8. Geometry and Cloaking Devices

    NASA Astrophysics Data System (ADS)

    Ochiai, T.; Nacher, J. C.

    2011-09-01

    Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

  9. Photonic Bandgap (PBG) Shielding Technology

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.

    2007-01-01

    Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects

  10. Twist knot cerclage wire: the appropriate wire tension for knot construction and fracture stability.

    PubMed

    Harnroongroj, Thossart

    1998-09-01

    OBJECTIVE: The aim was to find the best wire tension in order to permit a reliable first twist and simultaneously provide the best stability of fracture fixation from the twist knot cerclage wire. DESIGN: Wires at different distal tensions, looped around the fracture, were measured during twist and compared with the yield strength of the wire. Then, the fracture stability of the twist knot cerclage wire was determined from the pull-out strength. METHODS: In order to measure wire tension during twist knot construction, an instrument was designed using the tension load cell of a universal testing machine, a 15 degrees oblique osteotomy femoral shaft and 1.25 mm diameter wire. A wire tensioner and a pair of extraction grips were then used for measuring the pull-out strength of the cerclage wire fixation. RESULT: Three wire tensions (160, 200 and 240 N) were used as looped wire for the first twist knot construction. The 200 N tension cerclage wire provided the best fracture stability. CONCLUSION: It was found that 200 N was the best wire tension for the construction of a twist knot cerclage wire. RELEVANCE: When a cerclage wire is twisted at a femoral shaft using 1.25 mm diameter wire, a wire tension of 200 N should be used to achieve a reliable first twist and the best stability of fracture fixation.

  11. Quantitative assessment of tension in wires of fine-wire external fixators.

    PubMed

    Dong, Yin; Saleh, Micheal; Yang, Lang

    2005-01-01

    Fine-wire fixators are widely used in fracture management. Stable fixation requires the wires maintaining tension throughout the treatment. Clinical experience indicates that wire site complications relate to wire tension. However, there lacks a method to assess wire tension quantitatively in the clinic. The objective of this study was to develop a quantitative assessment method for in situ wire tension and to investigate the factors that influence the assessment. An apparatus was developed based on a linear variable differential transformer (LVDT) displacement transducer that measured the deflection of the testing wire with respect to a parallel reference wire when a constant transverse force of 30N was applied to the testing wire. The wire deflection measured was correlated with the wire tension measured by the force transducer. The experiment was performed under different conditions to assess the effect of bone-clamp distance, reference wire tension, number of wires, and fracture stiffness. The results showed that there was a significant and negative correlation between wire tension and deflection and the bone-clamp distance was the most important factor that affected the wire tension-deflection relationship. The assessment method makes it possible to investigate the relationship between wire tension and wire site complications in the clinic.

  12. Designing potentials by sculpturing wires

    SciTech Connect

    Della Pietra, Leonardo; Aigner, Simon; Groth, Soenke; Hagen, Christoph von; Schmiedmayer, Joerg; Bar-Joseph, Israel; Lezec, Henri J.

    2007-06-15

    Magnetic trapping potentials for atoms on atom chips are determined by the current flow in the chip wires. By modifying the shape of the conductor we can realize specialized current flow patterns and therefore microdesign the trapping potentials. We have demonstrated this by nano-machining an atom chip using the focused ion beam technique. We built a trap, a barrier, and using a Bose-Einstein Condensate as a probe we showed that by polishing the conductor edge the potential roughness on the selected wire can be reduced. Furthermore, we give different other designs and discuss the creation of a one-dimensional magnetic lattice on an atom chip.

  13. Wire Detection Algorithms for Navigation

    NASA Technical Reports Server (NTRS)

    Kasturi, Rangachar; Camps, Octavia I.

    2002-01-01

    In this research we addressed the problem of obstacle detection for low altitude rotorcraft flight. In particular, the problem of detecting thin wires in the presence of image clutter and noise was studied. Wires present a serious hazard to rotorcrafts. Since they are very thin, their detection early enough so that the pilot has enough time to take evasive action is difficult, as their images can be less than one or two pixels wide. Two approaches were explored for this purpose. The first approach involved a technique for sub-pixel edge detection and subsequent post processing, in order to reduce the false alarms. After reviewing the line detection literature, an algorithm for sub-pixel edge detection proposed by Steger was identified as having good potential to solve the considered task. The algorithm was tested using a set of images synthetically generated by combining real outdoor images with computer generated wire images. The performance of the algorithm was evaluated both, at the pixel and the wire levels. It was observed that the algorithm performs well, provided that the wires are not too thin (or distant) and that some post processing is performed to remove false alarms due to clutter. The second approach involved the use of an example-based learning scheme namely, Support Vector Machines. The purpose of this approach was to explore the feasibility of an example-based learning based approach for the task of detecting wires from their images. Support Vector Machines (SVMs) have emerged as a promising pattern classification tool and have been used in various applications. It was found that this approach is not suitable for very thin wires and of course, not suitable at all for sub-pixel thick wires. High dimensionality of the data as such does not present a major problem for SVMs. However it is desirable to have a large number of training examples especially for high dimensional data. The main difficulty in using SVMs (or any other example-based learning

  14. Plasma spraying with wire feedstock

    SciTech Connect

    Scholl, M.

    1994-12-31

    Plasma spraying has been limited to using powder feedstocks for a number of reasons. One limitation has been the low energy output of conventional plasma guns. The advent of high energy plasma spraying (HEPS) devices and the associated technology has effectively removed this functional limitation. With HEPS, the combination of high gas velocities and high thermal plasma temperatures coupled with a large exit gas volume enables wire and rod feedstocks to be effectively utilized. Rather than a bulk melting mechanism, a model based on ablation phenomena is considered. The paper examines an analysis of melting phenomena and presents a simple model for molten droplet formation for plasma spraying using wire feedstocks.

  15. Pyramidal GaAs/AlzGa1-zAs quantum wire/dot systems with controlled heterostructure potential

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Ganière, J. D.; He, Z. B.; Karlsson, K. F.; Byszewski, M.; Pelucchi, E.; Rudra, A.; Kapon, E.

    2010-10-01

    The structural and optical properties of controlled-heterostructure-potential, low-dimensional GaAs/AlGaAs nanostructures self-formed during organometallic chemical vapor deposition in tetrahedral pyramids etched in (111)B-GaAs substrates, are investigated using electron microscopy, cathodoluminescence, photoluminescence (PL), photon correlation spectroscopy, and theoretical modeling. Quantum wires/dots with AlGaAs cores with growth-controlled dimensions are formed, with a system of well-defined, low-dimensional nanostructure barriers around them. Transitions between carrier states confined in the AlGaAs quantum wires and dots are identified in the PL spectra, with features in good agreement with model calculations. Emission of single-photons and bunched-photon pairs is observed using temporal photon correlation spectroscopy. This self-formed nanostructure system provides new ways for shaping low-dimensional quantum structures and their heterostructure environment.

  16. Voltage plateaus on V( I) curves of long quasi-one-dimensional superconducting wires (without microwave irradiation)

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. I.; Firsov, A. A.

    2016-11-01

    Segments of an almost constant voltage (plateaus) on the V( I) curves of long quasi-one-dimensional superconducting aluminum wires placed in a magnetic field are found slightly below T c, which are unexpected at the parameters and geometry considered in this work. These plateaus are assumingly attributed to subharmonics of the superconducting gap and are due to multiple Andreev reflection and strong quasiparticle heating, which occur in the nonequilibrium region of a wire. The plateaus indicate the coexistence of superconductivity and dissipation in these wires. These results cannot be described by the existing theories.

  17. Photonic Nanojets.

    PubMed

    Heifetz, Alexander; Kong, Soon-Cheol; Sahakian, Alan V; Taflove, Allen; Backman, Vadim

    2009-09-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet's minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter d(ν) perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as d(ν)3 for a fixed λ. This perturbation is much slower than the d(ν)6 dependence of Rayleigh scattering for the same nanoparticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-μm diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000(th) the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applications of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage.

  18. Photonic Nanojets

    PubMed Central

    Heifetz, Alexander; Kong, Soon-Cheol; Sahakian, Alan V.; Taflove, Allen; Backman, Vadim

    2009-01-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter dν perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as dν3 for a fixed λ. This perturbation is much slower than the dν6 dependence of Rayleigh scattering for the same nanoparticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-μm diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000th the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applications of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage. PMID:19946614

  19. Photon calorimeter

    DOEpatents

    Chow, Tze-Show

    1988-04-22

    A photon calorimeter is provided that comprises a laminar substrate that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating, that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions, are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly. 4 figs.

  20. Photon Calorimeter

    DOEpatents

    Chow, Tze-Show

    1989-01-01

    A photon calorimeter (20, 40) is provided that comprises a laminar substrate (10, 22, 42) that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating (28, 48, 52), that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions (30, 50, 54) are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly.

  1. Electrical wire insulation and electromagnetic coil

    DOEpatents

    Bich, George J.; Gupta, Tapan K.

    1984-01-01

    An electromagnetic coil for high temperature and high radiation application in which glass is used to insulate the electrical wire. A process for applying the insulation to the wire is disclosed which results in improved insulation properties.

  2. Put Your Cable Wiring to the Test.

    ERIC Educational Resources Information Center

    Day, C. William

    2001-01-01

    Discusses why schools and universities should use testing procedures in any wire bid specification for cable wiring and also know how experienced the installers are in testing and installing structured cabling systems. Key cabling terms are included. (GR)

  3. Wire Capture Programs for Macintosh and IBM.

    ERIC Educational Resources Information Center

    Wiley, Gale

    1989-01-01

    Discusses wire capture programs (computer programs which gather and process wire services such as the Associated Press or United Press) for computer labs in journalism departments. Describes details of such programs for Macintosh, IBM, and IBM clones. (SR)

  4. Wire Capture Programs for Macintosh and IBM.

    ERIC Educational Resources Information Center

    Wiley, Gale

    1989-01-01

    Discusses wire capture programs (computer programs which gather and process wire services such as the Associated Press or United Press) for computer labs in journalism departments. Describes details of such programs for Macintosh, IBM, and IBM clones. (SR)

  5. Quality control of microelectronic wire bonds

    NASA Technical Reports Server (NTRS)

    Thiel, R. A.; Schmidt, G. D.

    1975-01-01

    Report evaluates ultrasonic bonding of small-diameter aluminum wire joined to ceramic substrates metalized with thin-film and thick-film gold. Quick testing technique for nondestructive location of poor wire bonds is also presented.

  6. Evaluation of high temperature stranded hookup wire

    NASA Technical Reports Server (NTRS)

    Donnelly, J. H.; Moore, H. J., Jr.

    1967-01-01

    Tests are performed on wire and insulation materials to determine selection for electronic space assemblies. Wire characteristics of tensile strength, flexibility, conductivity, and general workability are tested. Knowledge of the advantages and limitations of these materials should prevent overspecification.

  7. 49 CFR 393.28 - Wiring systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Lamps, Reflective Devices, and Electrical Wiring § 393.28 Wiring systems...

  8. 49 CFR 393.28 - Wiring systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Lamps, Reflective Devices, and Electrical Wiring § 393.28 Wiring systems...

  9. 49 CFR 393.28 - Wiring systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Lamps, Reflective Devices, and Electrical Wiring § 393.28 Wiring systems...

  10. Anode wire aging tests with selected gases

    SciTech Connect

    Kadyk, J.; Wise, J.; Hess, D.; Williams, M. )

    1990-04-01

    As a continuation of earlier wire aging investigations, additional candidates for wire chamber gas and wire have been tested. These include the gases: argon/ethane, HRS gas, dimethyl ether, carbon dioxide/ethane, and carbon tetrafluoride/isobutane. Wires used were: gold- plated tungsten, Stablohm, Nicotin, and Stainless Steel. Measurements were made of the effects upon wire aging of impurities from plumbing materials or contamination from various types of oil. Attempts were made to induce wire aging by adding measured amounts of oxygen and halogen (methyl chloride) with negative results. In this paper, the possible role of electronegativity in the wire aging process is discussed, and measurements of electronegativity are made with several single carbon Freons, using both an electron capture detector and a wire chamber operating with dimethyl ether.

  11. New insulation constructions for aerospace wiring applications

    NASA Technical Reports Server (NTRS)

    Slenski, George

    1994-01-01

    Outlined in this presentation is the background to insulation constructions for aerospace wiring applications, the Air Force wiring policy, the purpose and contract requirements of new insulation constructions, the test plan, and the test results.

  12. Strain and Texture in Al-Interconnect Wires Measured by X-Ray Microbeam Diffraction

    SciTech Connect

    Budai, J.D.; Chung, J.-S.; Ice, G.E.; Larson, B.C.; Lowe, W.P.; Tamura, N.; Tischler, J.Z.; Williams, E.L.; Yoon, M.

    1999-04-05

    The local strain and texture in Al interconnect wires have been investigated using white and monochromatic x-ray microbeams on the MHATTCAT undulator beam line at the Advanced Photon Source. Intergrain and intragrain orientations were obtained with ~0.01 degree sensitivity using white beam measurements on wide Al pads (~100 Mu-m) and thin (2 Mu-m) Al wires. Orientation changes of up to 1 degree were found within individual grains of the (111) textured Al interconnects. Deviatoric strain measurements indicate small intragranular strain variations, but intergranular strain variations were found to be quite large.

  13. Geometry of spinor regularization

    NASA Technical Reports Server (NTRS)

    Hestenes, D.; Lounesto, P.

    1983-01-01

    The Kustaanheimo theory of spinor regularization is given a new formulation in terms of geometric algebra. The Kustaanheimo-Stiefel matrix and its subsidiary condition are put in a spinor form directly related to the geometry of the orbit in physical space. A physically significant alternative to the KS subsidiary condition is discussed. Derivations are carried out without using coordinates.

  14. Sliding vane geometry turbines

    DOEpatents

    Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

    2014-12-30

    Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

  15. Listening to Geometry

    ERIC Educational Resources Information Center

    Cooper, Brett D.; Barger, Rita

    2009-01-01

    The many connections between music and mathematics are well known. The length of a plucked string determines its tone, the time signature of a piece of music is a ratio, and note durations are measured in fractions. One connection commonly overlooked is that between music and geometry--specifically, geometric transformations, including…

  16. GEOMETRY, TENTATIVE GUIDES.

    ERIC Educational Resources Information Center

    KLIER, KATHERINE M.

    PRESENTED IS A FUSED COURSE IN PLANE, SOLID, AND COORDINATE GEOMETRY. ELEMENTARY SET THEORY, LOGIC, AND THE PRINCIPLE OF SEPARATION PROVIDE UNIFYING THREADS THROUGHOUT THE TEXT. THE TWO CURRICULUM GUIDES HAVE BEEN PREPARED FOR USE WITH TWO DIFFERENT TEXTS. EITHER CURRICULUM GUIDE MAY BE USED DEPENDING UPON THE CHOICE OF THE TEACHER AND THE NEEDS…

  17. The Helen of Geometry

    ERIC Educational Resources Information Center

    Martin, John

    2010-01-01

    The cycloid has been called the Helen of Geometry, not only because of its beautiful properties but also because of the quarrels it provoked between famous mathematicians of the 17th century. This article surveys the history of the cycloid and its importance in the development of the calculus.

  18. Core Geometry Manual.

    ERIC Educational Resources Information Center

    Hirata, Li Ann

    Core Geometry is a course offered in the Option Y sequence of the high school mathematics program described by the Hawaii State Department of Education's guidelines. The emphasis of this course is on the general awareness and use of the relationships among points, lines, and figures in planes and space. This sample course is based on the…

  19. Emergent Hyperbolic Network Geometry

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph

    2017-02-01

    A large variety of interacting complex systems are characterized by interactions occurring between more than two nodes. These systems are described by simplicial complexes. Simplicial complexes are formed by simplices (nodes, links, triangles, tetrahedra etc.) that have a natural geometric interpretation. As such simplicial complexes are widely used in quantum gravity approaches that involve a discretization of spacetime. Here, by extending our knowledge of growing complex networks to growing simplicial complexes we investigate the nature of the emergent geometry of complex networks and explore whether this geometry is hyperbolic. Specifically we show that an hyperbolic network geometry emerges spontaneously from models of growing simplicial complexes that are purely combinatorial. The statistical and geometrical properties of the growing simplicial complexes strongly depend on their dimensionality and display the major universal properties of real complex networks (scale-free degree distribution, small-world and communities) at the same time. Interestingly, when the network dynamics includes an heterogeneous fitness of the faces, the growing simplicial complex can undergo phase transitions that are reflected by relevant changes in the network geometry.

  20. Emergent Hyperbolic Network Geometry.

    PubMed

    Bianconi, Ginestra; Rahmede, Christoph

    2017-02-07

    A large variety of interacting complex systems are characterized by interactions occurring between more than two nodes. These systems are described by simplicial complexes. Simplicial complexes are formed by simplices (nodes, links, triangles, tetrahedra etc.) that have a natural geometric interpretation. As such simplicial complexes are widely used in quantum gravity approaches that involve a discretization of spacetime. Here, by extending our knowledge of growing complex networks to growing simplicial complexes we investigate the nature of the emergent geometry of complex networks and explore whether this geometry is hyperbolic. Specifically we show that an hyperbolic network geometry emerges spontaneously from models of growing simplicial complexes that are purely combinatorial. The statistical and geometrical properties of the growing simplicial complexes strongly depend on their dimensionality and display the major universal properties of real complex networks (scale-free degree distribution, small-world and communities) at the same time. Interestingly, when the network dynamics includes an heterogeneous fitness of the faces, the growing simplicial complex can undergo phase transitions that are reflected by relevant changes in the network geometry.

  1. The Geometry of Viruses.

    ERIC Educational Resources Information Center

    Case, Christine L.

    1991-01-01

    Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)

  2. Origami, Geometry and Art

    ERIC Educational Resources Information Center

    Wares, Arsalan; Elstak, Iwan

    2017-01-01

    The purpose of this paper is to describe the mathematics that emanates from the construction of an origami box. We first construct a simple origami box from a rectangular sheet and then discuss some of the mathematical questions that arise in the context of geometry and algebra. The activity can be used as a context for illustrating how algebra…

  3. Making Solid Geometry Solid.

    ERIC Educational Resources Information Center

    Hartz, Viggo

    1981-01-01

    Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

  4. Emergent Hyperbolic Network Geometry

    PubMed Central

    Bianconi, Ginestra; Rahmede, Christoph

    2017-01-01

    A large variety of interacting complex systems are characterized by interactions occurring between more than two nodes. These systems are described by simplicial complexes. Simplicial complexes are formed by simplices (nodes, links, triangles, tetrahedra etc.) that have a natural geometric interpretation. As such simplicial complexes are widely used in quantum gravity approaches that involve a discretization of spacetime. Here, by extending our knowledge of growing complex networks to growing simplicial complexes we investigate the nature of the emergent geometry of complex networks and explore whether this geometry is hyperbolic. Specifically we show that an hyperbolic network geometry emerges spontaneously from models of growing simplicial complexes that are purely combinatorial. The statistical and geometrical properties of the growing simplicial complexes strongly depend on their dimensionality and display the major universal properties of real complex networks (scale-free degree distribution, small-world and communities) at the same time. Interestingly, when the network dynamics includes an heterogeneous fitness of the faces, the growing simplicial complex can undergo phase transitions that are reflected by relevant changes in the network geometry. PMID:28167818

  5. Making Solid Geometry Solid.

    ERIC Educational Resources Information Center

    Hartz, Viggo

    1981-01-01

    Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

  6. Listening to Geometry

    ERIC Educational Resources Information Center

    Cooper, Brett D.; Barger, Rita

    2009-01-01

    The many connections between music and mathematics are well known. The length of a plucked string determines its tone, the time signature of a piece of music is a ratio, and note durations are measured in fractions. One connection commonly overlooked is that between music and geometry--specifically, geometric transformations, including…

  7. Fractal geometry of music.

    PubMed Central

    Hsü, K J; Hsü, A J

    1990-01-01

    Music critics have compared Bach's music to the precision of mathematics. What "mathematics" and what "precision" are the questions for a curious scientist. The purpose of this short note is to suggest that the mathematics is, at least in part, Mandelbrot's fractal geometry and the precision is the deviation from a log-log linear plot. PMID:11607061

  8. Teaching Geometry with Tangrams.

    ERIC Educational Resources Information Center

    Russell, Dorothy S.; Bologna, Elaine M.

    1982-01-01

    Geometry is viewed as the most neglected area of the elementary school mathematics curriculum. Tangram activities provide numerous worthwhile mathematical experiences for children. A method of constructing tangrams through paper folding is followed by suggested spatial visualization, measurement, and additional activities. (MP)

  9. Geoff Giles and Geometry

    ERIC Educational Resources Information Center

    Fielker, David

    2007-01-01

    Geoff Giles died suddenly in 2005. He was a highly original thinker in the field of geometry teaching. As early as 1964, when teaching at Strathallen School in Perth, he was writing in "MT27" about constructing tessellations by modifying the sides of triangles and (irregular) quadrilaterals to produce what he called "trisides" and "quadrisides".…

  10. Origami, Geometry and Art

    ERIC Educational Resources Information Center

    Wares, Arsalan; Elstak, Iwan

    2017-01-01

    The purpose of this paper is to describe the mathematics that emanates from the construction of an origami box. We first construct a simple origami box from a rectangular sheet and then discuss some of the mathematical questions that arise in the context of geometry and algebra. The activity can be used as a context for illustrating how algebra…

  11. The Geometry of Viruses.

    ERIC Educational Resources Information Center

    Case, Christine L.

    1991-01-01

    Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)

  12. Gravity is Geometry.

    ERIC Educational Resources Information Center

    MacKeown, P. K.

    1984-01-01

    Clarifies two concepts of gravity--those of a fictitious force and those of how space and time may have geometry. Reviews the position of Newton's theory of gravity in the context of special relativity and considers why gravity (as distinct from electromagnetics) lends itself to Einstein's revolutionary interpretation. (JN)

  13. Geometry and physics

    PubMed Central

    Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel

    2010-01-01

    We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology. PMID:20123740

  14. Geoff Giles and Geometry

    ERIC Educational Resources Information Center

    Fielker, David

    2007-01-01

    Geoff Giles died suddenly in 2005. He was a highly original thinker in the field of geometry teaching. As early as 1964, when teaching at Strathallen School in Perth, he was writing in "MT27" about constructing tessellations by modifying the sides of triangles and (irregular) quadrilaterals to produce what he called "trisides" and "quadrisides".…

  15. Gravity is Geometry.

    ERIC Educational Resources Information Center

    MacKeown, P. K.

    1984-01-01

    Clarifies two concepts of gravity--those of a fictitious force and those of how space and time may have geometry. Reviews the position of Newton's theory of gravity in the context of special relativity and considers why gravity (as distinct from electromagnetics) lends itself to Einstein's revolutionary interpretation. (JN)

  16. Advanced geometries and regimes

    SciTech Connect

    Bulanov, S. S.; Bulanov, S. V.; Turchetti, G.; Limpouch, J.; Klimo, O.; Psikal, J.; Margarone, D.; Korn, G.

    2013-07-26

    We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project.

  17. LSP Calculations of Cone-Wire Experiments

    SciTech Connect

    Town, R J; Cottrill, L A; Key, M H; Kruer, W L; Langdon, A B; Lasinski, B F; McCandless, B C; Myatt, J F; Park, H S; Remington, B A; Snavely, R A; Still, C H; Tabak, M; Welch, D R; Wilks, S C

    2005-06-13

    Recent experiments at the Institute of Laser Engineering (ILE) in Japan [1] and at Rutherford Appleton Laboratory (RAL) in the United Kingdom [2] have shown good coupling of short-pulse high-intensity laser light into high-energy electrons channeled down a narrow fiber. Such target configurations are being considered as backlighter targets on the National Ignition Facility (NIF). We will report on LSP calculations of these cone-wire experiments and other candidate target configurations. These calculations also give insight into the transport of MeV-electrons, which remains the critical issue for the achievement of fast ignition [3]. The LSP code uses a direct implicit particle-in-cell (PIC) algorithm in 2 or 3 dimensions to solve for beam particle transport, while treating the background particles as a fluid [4]. We have modified LSP to produce K{alpha} photons in a non-interfering manner and will show calculated absolute K{alpha} yields for the experiments reported by Key [2].

  18. Geometry of PDE's. IV

    NASA Astrophysics Data System (ADS)

    Prástaro, Agostino

    2008-02-01

    Following our previous results on this subject [R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(I): Webs on PDE's and integral bordism groups. The general theory, Adv. Math. Sci. Appl. 17 (2007) 239-266; R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(II): Webs on PDE's and integral bordism groups. Applications to Riemannian geometry PDE's, Adv. Math. Sci. Appl. 17 (2007) 267-285; A. Prástaro, Geometry of PDE's and Mechanics, World Scientific, Singapore, 1996; A. Prástaro, Quantum and integral (co)bordism in partial differential equations, Acta Appl. Math. (5) (3) (1998) 243-302; A. Prástaro, (Co)bordism groups in PDE's, Acta Appl. Math. 59 (2) (1999) 111-201; A. Prástaro, Quantized Partial Differential Equations, World Scientific Publishing Co, Singapore, 2004, 500 pp.; A. Prástaro, Geometry of PDE's. I: Integral bordism groups in PDE's, J. Math. Anal. Appl. 319 (2006) 547-566; A. Prástaro, Geometry of PDE's. II: Variational PDE's and integral bordism groups, J. Math. Anal. Appl. 321 (2006) 930-948; A. Prástaro, Th.M. Rassias, Ulam stability in geometry of PDE's, Nonlinear Funct. Anal. Appl. 8 (2) (2003) 259-278; I. Stakgold, Boundary Value Problems of Mathematical Physics, I, The MacMillan Company, New York, 1967; I. Stakgold, Boundary Value Problems of Mathematical Physics, II, Collier-MacMillan, Canada, Ltd, Toronto, Ontario, 1968], integral bordism groups of the Navier-Stokes equation are calculated for smooth, singular and weak solutions, respectively. Then a characterization of global solutions is made on this ground. Enough conditions to assure existence of global smooth solutions are given and related to nullity of integral characteristic numbers of the boundaries. Stability of global solutions are related to some characteristic numbers of the space-like Cauchy dataE Global solutions of variational problems constrained by (NS) are classified by means of suitable integral bordism groups too.

  19. NEMA wire and cable standards development programs

    NASA Technical Reports Server (NTRS)

    Baird, Robert W.

    1994-01-01

    The National Electrical Manufacturers Association (NEMA) is the nation's largest trade association for manufacturers of electrical equipment. Its member companies produce components, end-use equipment and systems for the generation, transmission, distribution, control and use of electricity. The wire and cable division is presented in 6 sections: building wire and cable, fabricated conductors, flexible cords, high performance wire and cable, magnet wire, and power and control cable. Participating companies are listed.

  20. Life prediction of aging aircraft wiring systems

    NASA Technical Reports Server (NTRS)

    Slenski, George

    1995-01-01

    The program goal is to develop a computerized life prediction model capable of identifying present aging progress and predicting end of life for aircraft wiring. A summary is given in viewgraph format of progress made on phase 1 objectives, which were to identify critical aircraft wiring problems; relate most common failures identified to the wire mechanism causing the failure; assess wiring requirments, materials, and stress environment for fighter aircraft; and demonstrate the feasibility of a time-temperature-environment model.

  1. Further Studies Of Hot-Wire Anemometry

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert; Logan, Pamela; Bershader, Daniel

    1990-01-01

    Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Represents extension of work described in "Hot-Wire Anemometry Versus Laser-Induced Fluorescence" (ARC-11802). Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF).

  2. Novel Wiring Technologies for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Gibson, Tracy L.; Parrish, Lewis M.

    2014-01-01

    Because wire failure in aerospace vehicles could be catastrophic, smart wiring capabilities have been critical for NASA. Through the years, researchers at Kennedy Space Center (KSC) have developed technologies, expertise, and research facilities to meet this need. In addition to aerospace applications, NASA has applied its knowledge of smart wiring, including self-healing materials, to serve the aviation industry. This webinar will discuss the development efforts of several wiring technologies at KSC and provide insight into both current and future research objectives.

  3. Moving Large Wiring-Harness Boards

    NASA Technical Reports Server (NTRS)

    Shepherd, Samuel D.; Gurman, Isaac

    1990-01-01

    Carrier for wiring-harness fabrication boards enables lone operator to move board easily and safely. Holds harness while operator fabricating, while being stored, and being transported to equipment frame for mounting. When positioned for assembly of wiring harness, board and carrier give operator easy and convenient access to wires and cables, when positioned for transfer of wiring harness to or from storage area, carrier holds board securely while moved by one person.

  4. Pool boiling of water on nano-structured micro wires at sub-atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Arya, Mahendra; Khandekar, Sameer; Pratap, Dheeraj; Ramakrishna, S. Anantha

    2016-09-01

    Past decades have seen active research in enhancement of boiling heat transfer by surface modifications. Favorable surface modifications are expected to enhance boiling efficiency. Several interrelated mechanisms such as capillarity, surface energy alteration, wettability, cavity geometry, wetting transitions, geometrical features of surface morphology, etc., are responsible for change in the boiling behavior of modified surfaces. Not much work is available on pool boiling at low pressures on microscale/nanoscale geometries; low pressure boiling is attractive in many applications wherein low operating temperatures are desired for a particular working fluid. In this background, an experimental setup was designed and developed to investigate the pool boiling performance of water on (a) plain aluminum micro wire (99.999 % pure) and, (b) nano-porous alumina structured aluminum micro wire, both having diameter of 250 µm, under sub-atmospheric pressure. Nano-structuring on the plain wire surface was achieved via anodization. Two samples, A and B of anodized wires, differing by the degree of anodization were tested. The heater length scale (wire diameter) was much smaller than the capillary length scale. Pool boiling characteristics of water were investigated at three different sub-atmospheric pressures of 73, 123 and 199 mbar (corresponding to T sat = 40, 50 and 60 °C). First, the boiling characteristics of plain wire were measured. It was noticed that at sub-atmospheric pressures, boiling heat transfer performance for plain wire was quite low due to the increased bubble sizes and low nucleation site density. Subsequently, boiling performance of nano-structured wires (both Sample A and Sample B) was compared with plain wire and it was noted that boiling heat transfer for the former was considerably enhanced as compared to the plain wire. This enhancement is attributed to increased nucleation site density, change in wettability and possibly due to enhanced pore scale

  5. 30 CFR 75.906 - Trailing cables for mobile equipment, ground wires, and ground check wires.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cables for mobile equipment, ground wires, and ground check wires. 75.906 Section 75.906 Mineral Resources MINE SAFETY AND HEALTH..., ground wires, and ground check wires. Trailing cables for mobile equipment shall contain one or more...

  6. 30 CFR 75.906 - Trailing cables for mobile equipment, ground wires, and ground check wires.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Trailing cables for mobile equipment, ground wires, and ground check wires. 75.906 Section 75.906 Mineral Resources MINE SAFETY AND HEALTH..., ground wires, and ground check wires. Trailing cables for mobile equipment shall contain one or more...

  7. 30 CFR 75.906 - Trailing cables for mobile equipment, ground wires, and ground check wires.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Trailing cables for mobile equipment, ground wires, and ground check wires. 75.906 Section 75.906 Mineral Resources MINE SAFETY AND HEALTH..., ground wires, and ground check wires. Trailing cables for mobile equipment shall contain one or more...

  8. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding wires; capacity of wires. 75.701-4 Section 75.701-4 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE...; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

  9. Fabrication of tungsten wire needles

    SciTech Connect

    Roder, A.

    1983-02-01

    Fine point needles for field emissoin are conventionally produced by electrolytically or chemically etching tungsten wire. Points formed in this manner have a typical tip radius of about 0.5 microns and a cone angle of some 30 degrees. The construction of needle matrix detector chambers has created a need for tungsten needles whose specifications are: 20 mil tungsten wire, 1.5 inch total length, 3 mm-long taper (resulting in a cone angle of about 5 degrees), and 25 micron-radius point (similar to that found on sewing needles). In the process described here for producing such needles, tungsten wire, immersed in a NaOH solution and in the presence of an electrode, is connected first to an ac voltage and then to a dc supply, to form a taper and a point on the end of the wire immersed in the solution. The process parameters described here are for needles that will meet the above specifications. Possible variations will be discussed under each approprite heading.

  10. Plated wire random access memories

    NASA Technical Reports Server (NTRS)

    Gouldin, L. D.

    1975-01-01

    A program was conducted to construct 4096-work by 18-bit random access, NDRO-plated wire memory units. The memory units were subjected to comprehensive functional and environmental tests at the end-item level to verify comformance with the specified requirements. A technical description of the unit is given, along with acceptance test data sheets.

  11. Flexible substrate for printed wiring

    NASA Technical Reports Server (NTRS)

    Asakura, M.; Yabe, K.; Tanaka, H.; Soda, A.

    1982-01-01

    A very flexible substrate for printed wiring is disclosed which is composed of a blend of phenoxy resin-polyisocyanate-brominated epoxy resin in which the equivalent ration of the functional groups is hydroxyl grouped: isocyanate group: epoxy group = 1:0.2 to 2:0.5 to 3. The product has outstanding solder resistance and is applied to metal without using adhesives.

  12. Vocational Preparation Curriculum: Electrical Wiring.

    ERIC Educational Resources Information Center

    Usoro, Hogan

    This document is a curriculum guide for instructors teaching vocational preparation for electrical wiring to special needs students. The purpose of the curriculum guide is to provide minimum skills for disadvantaged and handicapped students entering the mainstream; to supplement vocational skills of those students already in a regular training…

  13. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

  14. Space Wire Upper Layer Protocols

    NASA Technical Reports Server (NTRS)

    Rakow, Glenn; Schnurr, Richard; Gilley, Daniel; Parkes, Steve

    2004-01-01

    This viewgraph presentation addresses efforts to provide a streamlined approach for developing SpaceWire Upper layer protocols which allows industry to drive standardized communication solutions for real projects. The presentation proposes a simple packet header that will allow flexibility in implementing a diverse range of protocols.

  15. Health care's 100 most wired.

    PubMed

    Solovy, A; Serb, C

    1999-02-01

    They're wired all right, and America's 100 most techno-savvy hospitals and health systems share one more thing: a commitment to using technology to link with employees, patients, suppliers, and insurers. "We want to be a health care travel agency for our community," says one chief information officer. "And we see Internet technology as a key."

  16. Ultrasonic Calibration Wire Test Phantom

    SciTech Connect

    Lehman, S K; Fisher, K A; Werve, M; Chambers, D H

    2004-09-24

    We designed and built a phantom consisting of vertical wires maintained under tension to be used as an ultrasonic test, calibration, and reconstruction object for the Lawrence Livermore National Laboratory annular array scanner. We provide a description of the phantom, present example data sets, preliminary reconstructions, example metadata, and MATLAB codes to read the data.

  17. Non-destructive X-ray examination of weft knitted wire structures

    NASA Astrophysics Data System (ADS)

    Obermann, M.; Ellouz, M.; Aumann, S.; Martens, Y.; Bartelt, P.; Klöcker, M.; Kordisch, T.; Ehrmann, A.; Weber, M. O.

    2016-07-01

    Conductive yarns or wires are often integrated in smart textiles to enable data or energy transmission. In woven fabrics, these conductive parts are fixed at defined positions and thus protected from external loads. Knitted fabrics, however, have relatively loose structures, resulting in higher impacts of possible mechanical forces on the individual yarns. Hence, metallic wires with smaller diameters in particular are prone to break when integrated in knitted fabrics. In a recent project, wires of various materials including copper, silver and nickel with diameters varying between 0.05 mm and 0.23 mm were knitted in combination with textile yarns. Hand flat knitting machines of appropriate gauges were used to produce different structures. On these samples, non-destructive examinations, using an industrial X-ray system Seifert x|cube (225 kV) equipped with a minifocus X-ray tube, were carried out, directly after knitting as well as after different mechanical treatments (tensile, burst, and washing tests). In this way, structural changes of the stitch geometry could be visualized before failure. In this paper, the loop geometries in the knitted fabrics are depicted depending on knitted structures, wire properties and the applied mechanical load. Consequently, it is shown which metallic wires and yarns are most suitable to be integrated into knitted smart textiles.

  18. Program EPICP: Electron photon interaction code, photon test module. Version 94.2

    SciTech Connect

    Cullen, D.E.

    1994-09-01

    The computer code EPICP performs Monte Carlo photon transport calculations in a simple one zone cylindrical detector. Results include deposition within the detector, transmission, reflection and lateral leakage from the detector, as well as events and energy deposition as a function of the depth into the detector. EPICP is part of the EPIC (Electron Photon Interaction Code) system. EPICP is designed to perform both normal transport calculations and diagnostic calculations involving only photons, with the objective of developing optimum algorithms for later use in EPIC. The EPIC system includes other modules that are designed to develop optimum algorithms for later use in EPIC; this includes electron and positron transport (EPICE), neutron transport (EPICN), charged particle transport (EPICC), geometry (EPICG), source sampling (EPICS). This is a modular system that once optimized can be linked together to consider a wide variety of particles, geometries, sources, etc. By design EPICP only considers photon transport. In particular it does not consider electron transport so that later EPICP and EPICE can be used to quantitatively evaluate the importance of electron transport when starting from photon sources. In this report I will merely mention where we expect the results to significantly differ from those obtained considering only photon transport from that obtained using coupled electron-photon transport.

  19. 30 CFR 57.12047 - Guy wires.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Guy wires. 57.12047 Section 57.12047 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12047 Guy wires. Guy wires of poles supporting high-voltage transmission lines shall meet the...

  20. 49 CFR 234.231 - Fouling wires.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Fouling wires. 234.231 Section 234.231... EMERGENCY NOTIFICATION SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway-rail grade crossing train detection circuit shall consist...

  1. 49 CFR 234.231 - Fouling wires.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Fouling wires. 234.231 Section 234.231... EMERGENCY NOTIFICATION SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway-rail grade crossing train detection circuit shall consist...

  2. 49 CFR 234.231 - Fouling wires.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Fouling wires. 234.231 Section 234.231... EMERGENCY NOTIFICATION SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway-rail grade crossing train detection circuit shall consist...

  3. Home and School Technology: Wired versus Wireless.

    ERIC Educational Resources Information Center

    Van Horn, Royal

    2001-01-01

    Presents results of informal research on smart homes and appliances, structured home wiring, whole-house audio/video distribution, hybrid cable, and wireless networks. Computer network wiring is tricky to install unless all-in-one jacketed cable is used. Wireless phones help installers avoid pre-wiring problems in homes and schools. (MLH)

  4. Home and School Technology: Wired versus Wireless.

    ERIC Educational Resources Information Center

    Van Horn, Royal

    2001-01-01

    Presents results of informal research on smart homes and appliances, structured home wiring, whole-house audio/video distribution, hybrid cable, and wireless networks. Computer network wiring is tricky to install unless all-in-one jacketed cable is used. Wireless phones help installers avoid pre-wiring problems in homes and schools. (MLH)

  5. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit. ...

  6. Braided cerclage wires: a biomechanical study.

    PubMed

    Steinberg, Ely L; Shavit, Ronen

    2011-04-01

    One of the drawbacks that makes many surgeons reluctant to use cerclage wires is the risk of periosteal vascular compromise. A new, easily applied braided wire configuration has been developed to improve mechanical wire gripping and to decrease the contact area between the hardware and the bony surface. Braided wires with two diameters (1 mm and 1.5 mm) were compared to single strand and double-strand wire configurations. The biomechanical properties, peak and elongation loads,and wire pressure imprint points of this new configuration were evaluated in the current study. The braided wire was found to have the same peak load as the double-strand wire (P = 0.315) and more than twice the peak load than the single-strand wire (P = 0.0001), but a much shorter elongation peak than the other two. The imprint test showed that the braided wire has an interrupted dotted pattern compared to the continuous circular one that characterises the single-strand and double strand wires, indicating less potential damage to the bone. The braided cerclage wire may decrease the extent of insult to the bone by decreasing the contact area between the hardware and the bony surface and by enhancing stability by reducing the elongation peak, affording increased fracture fixation stability. 2010 Elsevier Ltd. All rights reserved.

  7. 30 CFR 57.12047 - Guy wires.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Guy wires. 57.12047 Section 57.12047 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12047 Guy wires. Guy wires of poles supporting high-voltage transmission lines shall meet the...

  8. 47 CFR 32.2431 - Aerial wire.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other material used in the construction of such plant. (b) The cost of permits and privileges for the construction of cable and wire...

  9. Getting "Wired" for McLuhan's Cyberculture.

    ERIC Educational Resources Information Center

    McMurdo, George

    1995-01-01

    Examines the introduction of the computing magazine, "Wired", into the United Kingdom's (UK) market. Presents conversations with the founder and editorial staff of the UK edition, and discusses the accessibility of "Wired" via the World Wide Web. Describes 10 articles from United States "Wired" back-issues and…

  10. 75 FR 4584 - Wire Decking From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-28

    ... may be drawn or rolled and may have a round, square or other profile. Wire decking is sold in a... COMMISSION Wire Decking From China AGENCY: United States International Trade Commission. ACTION: Scheduling... retarded, by reason of subsidized and less-than-fair-value imports from China of wire decking, provided for...

  11. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit....

  12. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit....

  13. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit....

  14. 47 CFR 32.2431 - Aerial wire.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Aerial wire. 32.2431 Section 32.2431... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other material used in...

  15. 47 CFR 32.2431 - Aerial wire.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Aerial wire. 32.2431 Section 32.2431... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other material used in...

  16. 47 CFR 32.2431 - Aerial wire.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Aerial wire. 32.2431 Section 32.2431... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other material used in...

  17. 47 CFR 32.2431 - Aerial wire.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Aerial wire. 32.2431 Section 32.2431... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other material used in...

  18. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit....

  19. Tevatron direct photon results.

    SciTech Connect

    Kuhlmann, S.

    1999-09-21

    Tevatron direct photon results since DIS98 are reviewed. Two new CDF measurements are discussed, the Run Ib inclusive photon cross section and the photon + Muon cross section. Comparisons with the latest NLO QCD calculations are presented.

  20. Controlling electromagnetic scattering with wire metamaterial resonators.

    PubMed

    Filonov, Dmitry S; Shalin, Alexander S; Iorsh, Ivan; Belov, Pavel A; Ginzburg, Pavel

    2016-10-01

    Manipulation of radiation is required for enabling a span of electromagnetic applications. Since properties of antennas and scatterers are very sensitive to the surrounding environment, macroscopic artificially created materials are good candidates for shaping their characteristics. In particular, metamaterials enable controlling both dispersion and density of electromagnetic states, available for scattering from an object. As a result, properly designed electromagnetic environments could govern wave phenomena and tailor various characteristics. Here electromagnetic properties of scattering dipoles, situated inside a wire medium (metamaterial), are analyzed both numerically and experimentally. The effect of the metamaterial geometry, dipole arrangement inside the medium, and frequency of the incident radiation on the scattering phenomena is studied in detail. It is shown that the resonance of the dipole hybridizes with Fabry-Perot modes of the metamaterial, giving rise to a complete reshaping of electromagnetic properties. Regimes of controlled scattering suppression and super-scattering are experimentally observed. Numerical analysis is in agreement with the experiment, performed at the GHz spectral range. The reported approach to scattering control with metamaterials could be directly mapped into optical and infrared spectral ranges by employing scalability properties of Maxwell's equations.