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Sample records for mbi bending magnets

  1. Residual Field Correction of Pulsed Bending Magnet

    NASA Astrophysics Data System (ADS)

    Takano, Junpei; Igarashi, Susumu; Kamikubota, Norihiko; Meigo, Shin-ichiro; Sato, Kenichi; Shirakata, Masashi; Yamada, Shuei

    The Japan Proton Accelerator Research Complex (J-PARC) has an accelerator chain, Linac, Rapid Cycling Synchrotron (RCS), and Main Ring (MR). The RCS accelerates the proton beam up to 3 GeV every 40 msec. After the beam is extracted from the RCS, it is delivered to a beam transport line, which is 3NBT for the Material and Life Science Experimental Facility (MLF). Some bunches of the proton beam are bended from the 3NBT to another beam transport line, which is 3-50BT for the MR, by using a pulsed bending magnet (PB) [1]. However, the beam orbit in the 3NBT is kicked by the residual magnetic field of the PB. In order to correct the residual magnetic field, additional coils had been wound on the PB poles. As a result of scanning the current pattern of the correction coils, the orbit distortion in the 3NBT has been reduced.

  2. SRI CAT Section 1 bending magnet beamline description

    SciTech Connect

    Srajer, G.; Rodricks, B.; Assoufid, L.; Mills, D.M.

    1994-03-10

    This report discusses: APS bending magnet source; beamline layout; beamline optical components; beamline operation; time-resolved studies station; polarization studies station; and commissioning and operational schedule.

  3. Bending of magnetic filaments under a magnetic field

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Valera P.; Winklhofer, Michael

    2004-12-01

    Magnetic beads and superparamagnetic (SP) colloid particles have successfully been employed for micromechanical manipulation of soft material, in situ probing of elastic properties, and design of smart materials (ferrogels). Here we derive analytical expressions for the equilibrium shape of magnetic fibers, considering two end-member cases, (a) SP or single-domain particles concentrated at the free end of cantilevered rods or tubes, and (b) filaments consisting of SP particles, with this case being mathematically equivalent to tubes containing SP particles. Our analysis yields also metastable equilibrium states (MES’s), which only exist above a critical filament length, but become more stable with increasing magnetic field. The MES’s for case (a) are, like the ground state, circular arcs, but more strongly bent. The multiform MES’s in case (b), which comprise hairpin, sinuous, or even closed shapes, have recently been observed in experiments, too. We also study the effect of gravity on the balance between bending and magnetic energy, which leads to curves with inflection point if the influence of gravity is stronger than that of the magnetic field. Because of their simple experimental realization, case (a) magnetic filaments are deemed highly suitable for micromechanical experiments on long chains of polymer molecules. Another potential application of cantilevered magnetic filaments with magnetic material attached to the free end is in scanning probe microscopes. Because the magnetic field due to the magnetic tip is comparatively weak, the magnetization structure of the sample to be investigated would not be affected by the probe. Thus, for the examination of magnetically soft materials, probes in the form of magnetic filaments may hold advantages over tips usually employed in magnetic force microscopy.

  4. Twist-bend nematic liquid crystals in high magnetic fields.

    PubMed

    Challa, P K; Borshch, V; Parri, O; Imrie, C T; Sprunt, S N; Gleeson, J T; Lavrentovich, O D; Jákli, A

    2014-06-01

    We present magneto-optic measurements on two materials that form the recently discovered twist-bend nematic (N_{tb}) phase. This intriguing state of matter represents a fluid phase that is orientationally anisotropic in three directions and also exhibits translational order with periodicity several times larger than the molecular size. N_{tb} materials may also spontaneously form a visible, macroscopic stripe texture. We show that the optical stripe texture can be persistently inhibited by a magnetic field, and a 25T external magnetic field depresses the N-N_{tb} phase transition temperature by almost 1{∘}C. We propose a quantitative mechanism to account for this shift and suggest a Helfrich-Hurault-type mechanism for the optical stripe formation. PMID:25019707

  5. Light bending by nonlinear electrodynamics under strong electric and magnetic field

    SciTech Connect

    Kim, Jin Young; Lee, Taekoon E-mail: tlee@kunsan.ac.kr

    2011-11-01

    We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.

  6. A superconducting bending magnet system for a compact synchrotron light source

    SciTech Connect

    Green, M.A.; Garren, A.A.; Leung, E.M.; Madura, D.D.; Cline, D.B.; Kolonko, J.J.; Schachinger, L.C.

    1995-07-01

    High intensity, high energy X-rays for use in protein crystallography, nano-machining and medical applications, such as non invasive coronary angiography, can be produced by a 1.2 to 1.5 GeV electron storage ring compact light source with 6 to 8 tesla superconducting bending magnets. Because the bending magnets are to be superconducting, the storage ring energy can be over factor of two lower than a conventional storage ring that delivers same photon energy. The ring, which has superconducting bending magnets, is smaller in circumference and has the advantage of having fewer particles in the ring for a given x ray source intensity. The proposed storage ring is a separated function accelerator ring with six superconducting bending magnet units. Conventional quadruples and correction elements would be located between the bending magnets. Because the synchrotron radiation is generated in the bend, the superconducting bending magnets must have a warm vacuum chamber for the electron beam. Variations of a superferric magnet design have been studied for this application. This report presents a superferric H magnet design that can produce good quality magnetic field in a region that is 50 mm high by 100 mm wide. This modified superferric H magnet design has saturated iron poles but the magnetic flux is returned from one pole to the other through an unsaturated iron return path. The dipole magnet required for a compact storage ring must be physically short (380 mm long), and the field must fall off rapidly at the ends of the magnet. This report describes a preliminary design for a pair of 6.894 tesia, thirty degree bending magnets in a common vacuum vessel for use in a 1.5 GeV compact storage ring light source.

  7. Magnetic measurement of the pi bend dipole magnets for the IR-FEL at the Thomas Jefferson National Accelerator Facility

    SciTech Connect

    Biallas, G.; Douglas, D.; Karn, J.; Tremblay, K.

    1999-04-01

    A family of large bending dipoles has been successfully magnetically measured, installed and is operational in the high power IR-FEL. These magnets are unique in that they bend the beam 180 {degree} on a 1 meter radius. The optics requirements for the magnets include low fields, large horizontal apertures, tight field homogeneity, high repeatability of core field and integrated field, and control of the horizontal and vertical focusing terms that are designed into the magnets. Quantifying the optics requirements proved to be a difficult task, due to the magnet's mechanical construction and sharp bending radius. The process involved in measuring and achieving the results are discussed.

  8. Bioeconomy Initiative at MBI International

    SciTech Connect

    Kleff, Susanne, Ph.D.

    2011-11-30

    Di-carboxylic acids have the potential to replace petrochemicals used in the polymer industry (Werpy and Petersen, 2004). MBI developed a process for the production of succinic acid using a proprietary organism. During this work MBI assessed the feasibility to produce other carboxylic acids either using A. succinogenes or other organisms. The development of recombinant A. succinogenes strain derivatives for a mono-carboxylic acid through over-expression of enzymatic activities was successful. Fermentations achieved titers of 58 g/L for this organic acid. Recombinant strains that produced the same acid, but a different stereoisomer, reached titers of 10 g/L. Attempts to increase the titers for this isomer as well as other organic acids were unsuccessful. MBI is looking for commercial partners to pursue the development of recombinant A. succinogenes strains for the production of other organic acids. Attempts to develop recombinant strains of A. succinogenes for fumaric acid production through introduction of various antisense RNA constructs were unsuccessful. Alternative suitable organisms were evaluated and Rhizopus oryzae, a natural fumaric acid producer with potential for process improvements, was selected. A novel fermentation and one-step recovery process was developed that allowed capture of IP, produced titers of >80 g/L with a productivity of 1.8 g/L-h and 57% (g/g glucose) yield. The process was scaled to 2000 L pilot scale. The economic analysis projected a production cost of 72 c/lb. Recycling and re-use of the base was demonstrated and incorporated into the process. The ability of the organism to produce fumaric acid from other carbon sources and biomass hydrolysate was demonstrated. The production of other organic acids was evaluated and techno-economic de-risking roadmap documents were prepared.

  9. Critical Currents of MgB2 Wire and Tape in Magnetic Field under Bending Deformations

    NASA Astrophysics Data System (ADS)

    Abin, D. A.; Mineev, N. A.; Osipov, M. A.; Pokrovsky, S. V.; Rudnev, I. A.

    Nowadays MgB2 wires are attractive for designing real devices like motors and magnets. The latest production technologies allow to increase critical current value of wires. However, there is a problem of wire performance degradation under bending strain. Thus, there is a problem of manufacturing solenoids with small diameters, especially from ex situ MgB2 wires produced by powder-in-tube (PIT) technology. In this work, influence of bending on critical current Ic multifilament PIT ex situ MgB2 tape and wire has been studied. Critical current dependencies on external magnetic field Ic(H) were measured at liquid helium temperature in the range of fields from 2.5 T up to 8 T. Measurements were carried out in parallel (H||), and perpendicular (H⊥) orientation of external magnetic field to the sample surface. Voltage current characteristics (V-I) on tape samples were measured with bending on diameters D=30; 40; 60; 70; 80; 90;100 mm. It was shown that critical current density (Jc) decreases by 24% and by 28% for tape and wire respectively with decreasing bending diameter from 100 mm to 60 mm. It was found that the tape still had superconductive properties even with bending diameter D=30 mm, but its Jc decreased by 44% in comparison with Jc(D=100 mm). One more feature that was found is the appearance of resistive component in the voltage current characteristics for all bend diameters in magnetic fields H>3.5 T.

  10. Applications of circularly polarized photons at the ALS with a bend magnet source

    SciTech Connect

    Not Available

    1992-02-01

    The purpose of this workshop is to focus attention on, and to stimulate the scientific exploitation of, the natural polarization properties of bend-magnet synchrotron radiation at the ALS -- for research in biology, materials science, physics, and chemistry. The topics include: The Advanced Light Source; Magnetic Circular Dichroism and Differential Scattering on Biomolecules; Tests of Fundamental Symmetries; High {Tc} Superconductivity; Photoemission from Magnetic and Non-magnetic Solids; Studies of Highly Correlated Systems; and Instrumentation for Photon Transport and Polarization Measurements.

  11. A 6.3 T Bend Magnet for the Advanced Light Source

    SciTech Connect

    Taylor, C.E.; Caspi, S.

    1995-06-07

    The Advanced Light Source (ALS) is a 1.5 to 1.9 GeV high-brightness electron storage ring operating at Lawrence Berkeley Laboratory (LBL) that provides synchrotron radiation for a large variety of users. It Is proposed to replace three of the thirty six 1.5T, one meter long bend magnets with very sbort high-field superconductlng (SC) dipoles. These magnets would provide bend-magnet synchrotron radiation to six bcamlines with a critical energy of at least 6 keV that is much better suited for protein crystallography and other small-sample x-ray diffraction and adsorption studies, than is currently available at the ALS. The magnet design is described, including coil, yoke, magnetic field analysis, and cyrostat. A prototype magnet is under construction at LBL.

  12. Development of bending characteristics for the TPX TF magnet coil cable-in-conduit conductor

    SciTech Connect

    Grut, K.E.; Holbrook, R.L.; Hook, E.; Antaya, T.A.

    1996-12-31

    The conductor for the toroidal field (TF) magnet coils for the Tokamak Physics experiment (TPX) is an assembly of stranded Nb{sub 3}Sn superconductor sheathed by an Incoloy 908 conduit. The coil shape, when coupled with stiffness of the cable-in-conduit conductor (CICC) is such that conventional magnet winding techniques cannot be utilized. Therefore a bending and forming method will be employed in the TF coils. The cable will be reacted after bending because the reaction process hardens the conduit and also lowers the strain the cable can withstand without performance degradation. The Incoloy 908 conduit also work hardens quickly, necessitating the production of the required coil shape in one step without correction. This paper discusses the limiting processes for forming the TPX TF magnet geometry, the methods utilized in establishing the CICC bending characteristics and the methods employed to account for material springback so that a coil can be manufactured accurately and efficiently.

  13. The millimeter-wave bolometric interferometer (MBI)

    NASA Astrophysics Data System (ADS)

    Tucker, Gregory S.; Korotkov, Andrei L.; Gault, Amanda C.; Hyland, Peter O.; Malu, Siddharth; Timbie, Peter T.; Bunn, Emory F.; Keating, Brian G.; Bierman, Evan; O'Sullivan, Créidhe; Ade, Peter A. R.; Piccirillo, Lucio

    2008-07-01

    We report on the design and tests of a prototype of the Millimeter-wave Bolometric Interferometer (MBI). MBI is designed to make sensitive measurements of the polarization of the cosmic microwave background (CMB). It combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. The prototype, which we call MBI-4, views the sky directly through four corrugated horn antennas. MBI ultimately will have ~ 1000 antennas. These antennas have low sidelobes and nearly symmetric beam patterns, so spurious instrumental polarization from reflective optics is avoided. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines, determined by placement of the four antennas, results in sensitivity to CMB polarization fluctuations over the multipole range l = 150 - 270. The signals are combined with a Fizeau beam combiner and interference fringes are detected by an array of spider-web bolometers. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Initial tests and observations have been made at Pine Bluff Observatory (PBO) outside Madison, WI.

  14. The Millimeter-wave Bolometric Interferometer (MBI)

    NASA Astrophysics Data System (ADS)

    Gault, Amanda C.; Ade, P. A. R.; Bierman, E.; Bunn, E. F.; Hyland, P. O.; Keating, B. G.; Korotkov, A. L.; Malu, S. S.; O'Sullivan, C.; Piccirillo, L.; Timbie, P. T.; Tucker, G. S.

    2009-01-01

    We report on the design and tests of a prototype of the Millimeter-wave Bolometric Interferometer (MBI). MBI is designed to make sensitive measurements of the polarization of the cosmic microwave background (CMB). It combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. The prototype, which we call MBI-4, views the sky directly through four corrugated horn antennas. MBI ultimately will have 1000 antennas. These antennas have low sidelobes and nearly symmetric beam patterns, so spurious instrumental polarization from reflective optics is avoided. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines, determined by placement of the four antennas, results in sensitivity to CMB polarization fluctuations over the multipole range l = 150 - 270. The signals are combined with a Fizeau beam combiner and interference fringes are detected by an array of spiderweb bolometers. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Initial tests and observations have been made at Pine Bluff Observatory (PBO) outside Madison, WI. This work was supported by NASA grants NAG5-12758, NNX07AG82G, the Rhode Island Space Grant and the Wisconsin Space Grant.

  15. Bending of electromagnetic wave in an ultra-strong magnetic field

    SciTech Connect

    Kim, Jin Young

    2012-10-01

    We consider the bending of light by nonlinear electrodynamics when the magnetic field B exceeds the critical value B{sub c} = m{sup 2}c{sup 2}/e h-bar = 4.4 × 10{sup 9}T. Using the index of refraction derived from the analytic series representation in one-loop effective action of QED, we found the trajectory and the bending angle of light in geometric optics. The angle bent by ultra-strong magnetic field of magnetar was estimated and compared with the gravitational bending. The result may be useful in studying the lensing, birefringence, and other nonlinear quantum electrodynamic effects above B{sub c}.

  16. FINAL REPORT. CONSTRUCTION OF BENDING MAGNET BEAMLINE AT THE APS FOR ENVIRONMENTAL STUDIES

    EPA Science Inventory

    Design and construction of a bending magnet beamline at the Advanced Photon Source (APS) by the Pacific Northwest Consortium-Collaborative Access Team (PNC-CAT). The beamline will be optimized for x-ray absorption spectroscopy (XAS) studies with a major focus on environmental iss...

  17. Textile artificial magnetic conductor jacket for transmission enhancement between antennas under bending and wetness measurements

    NASA Astrophysics Data System (ADS)

    Kamardin, Kamilia; Rahim, Mohamad Kamal A.; Hall, Peter S.; Samsuri, Noor Asmawati; Latef, Tarik Abdul; Ullah, Mohammad Habib

    2016-04-01

    Textile artificial magnetic conductor (AMC) waveguide jacket for transmission enhancement between on-body antennas is proposed. Transmission characteristics between antennas with different orientations and placements are studied. Significant transmission enhancement is observed for all tested positions. Bending and wetness measurements are also conducted. Bending is found not to give significant effect to the antennas and AMC performance, while wetness yields severe performance distortion. However, the original performance is retrieved once the antennas and AMC dried. The proposed AMC jacket will act as a new approach for efficient wearable body-centric communications.

  18. MBI: Millimetre-wave bolometric interferometer

    NASA Astrophysics Data System (ADS)

    Ali, S.; Rossinot, P.; Piccirillo, L.; Gear, W. K.; Mauskopf, P.; Ade, P.; Haynes, V.; Timbie, P.

    2002-05-01

    We present the design of the prototype of a millimeter-wave bolometric interferometer (MBI). This interferometer uses two arrays bolometers as detectors. The combination of high sensitivity bolometers and interferometric imaging appears to be well suited for precision measurements in observational cosmology. .

  19. X-ray lasers at MBI

    NASA Astrophysics Data System (ADS)

    Janulewicz, Karol A.; Lucianetti, Antonio; Priebe, Gerd; Sandner, Wolfgang; Nickles, Peter-Viktor

    2003-10-01

    The state-of-the-art and the trends in development of table-top soft x-ray lasers (XRLs) with a special emphasis on the work of the Max Born Institute (MBI) are presented. Both, basic physics and some features of the output radiation crucial for applications are discussed as well.

  20. Solar wind magnetic field bending of Jovian dust trajectories.

    PubMed

    Zook, H A; Grün, E; Baguhl, M; Hamilton, D P; Linkert, G; Liou, J; Forsyth, R; Phillips, J L

    1996-11-29

    From September 1991 to October 1992, the cosmic dust detector on the Ulysses spacecraft recorded 11 short bursts, or streams, of dust. These dust grains emanated from the jovian system, and their trajectories were strongly affected by solar wind magnetic field forces. Analyses of the on-board measurements of these fields, and of stream approach directions, show that stream-associated dust grain masses are of the order of 10(-18) gram and dust grain velocities exceed 200 kilometers per second. These masses and velocities are, respectively, about 10(3) times less massive and 5 to 10 times faster than earlier reported. PMID:8929405

  1. X-ray laser program at MBI

    NASA Astrophysics Data System (ADS)

    Nickles, P. V.; Janulewicz, K. A.; Lucianetti, A.; Priebe, G.; Zigler, A.; Rocca, J. J.; Sandner, W.

    2002-11-01

    A survey of the Max Born Institute (MBI) activities in the field of X-ray lasers (XRLs) is presented. The main interest is focused on the transient soft X-ray lasers. Additionally, much work is put to look for new, efficient, compact (table-top) pumping schemes with a prospect to be applied in practice. The current state of the research and the plans for the future are described as well.

  2. Advantages of a Synchrotron Bending Magnet as the Sample Illuminator for a Wide-field X-ray Microscope

    SciTech Connect

    Feser, M.; Howells, M. R.; Kirz, J.; Rudati, J.; Yun, W.

    2012-09-01

    In our paper the choice between bending magnets and insertion devices as sample illuminators for a hard X-ray full-field microscope is investigated. An optimized bending-magnet beamline design is presented. Its imaging speed is very competitive with the performance of similar microscopes installed currently at insertion-device beamlines. The fact that imaging X-ray microscopes can accept a large phase space makes them very well suited to the output characteristics of bending magnets which are often a plentiful and paid-for resource. There exist opportunities at all synchrotron light sources to take advantage of this finding to build bending-magnet beamlines that are dedicated to transmission X-ray microscope facilities. We expect that demand for such facilities will increase as three-dimensional tomography becomes routine and advanced techniques such as mosaic tomography and XANES tomography (taking three-dimensional tomograms at different energies to highlight elemental and chemical differences) become more widespread.

  3. Curvature-Induced Bunch Self-Interaction for an Energy-Chirped Bunch in Magnetic Bends

    SciTech Connect

    Li, Rui

    2008-02-01

    Within the realm of classical electrodynamics, the curvature-induced bunch collective interaction in magnetic bends can be studied using effective forces in the canonical formulation of the coherent synchrotron radiation (CSR) effect. As an application of this canonical formulation, in this paper, for an electron distribution moving ultrarelativistically in a bending system, the dynamics of the particles in the distribution is derived from the Hamiltonian of the particles in terms of the bunch internal coordinates. The consequent Vlasov equation manifests explicitly how the phase-space distribution is perturbed by the effective CSR forces. In particular, we study the impact of an initial linear energy chirp of the bunch on the behavior of the effective longitudinal CSR force, which arises due to the modification of the retardation relation as a result of the energy-chirping- induced longitudinal-horizontal correlation of the bunch distribution (bunch tilt) in dispersive regions. Our study demonstrates clearly the time delay (or retardation) of the behavior of the effective longitudinal CSR force on a bunch in responding to the change of the bunch length in a magnetic bend. Our result also shows that the effective longitudinal CSR force for a bunch under full compression can have sensitive dependence on the transverse position of the test particle in the bunch for certain parameter regimes.

  4. Curvature-Induced Bunch Self-Interaction for an Energy-Chirped Bunch in Magnetic Bends

    SciTech Connect

    Rui Li

    2006-01-04

    The curvature-induced bunch collective interaction in magnetic bends can be studied using effective forces in the canonical formulation of the coherent synchrotron radiation (CSR) effect. In this paper, for an electron distribution moving ultrarelativistically in a bending system, the dynamics of a particle in the electron distribution is derived from the Hamiltonian of the particle in terms of the bunch internal coordinates. The consequent Vlasov equation manifests explicitly how the phase space distribution is perturbed by the effective CSR forces. In particular, we study the impact of an initial linear energy chirp of the bunch on the behavior of the effective longitudinal CSR force, which arises due to the modification of the retardation relation as a result of the energy-chirping-induced longitudinal-horizontal correlation of the bunch distribution (bunch tilt) in dispersive regions.

  5. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    SciTech Connect

    Kortright, J.B.; Rice, M.; Hussain, Z.

    1997-04-01

    Growing interest in utilizing circular polarization prompted the design of bend-magnet beamline 9.3.2 at the Advanced Light Source, covering the 30-1500 eV spectral region, to include vertical aperturing capabilities for optimizing the collection of circular polarization above and below the orbit plane. After commissioning and early use of the beamline, a multilayer polarimeter was used to characterize the polarization state of the beam as a function of vertical aperture position. This report partially summarizes the polarimetry measurements and compares results with theoretical calculations intended to simulate experimental conditions.

  6. Investigation of collisional effects within the bending magnet region of a DIII-D neutral beamline

    SciTech Connect

    Kessler, D.N.; Hong, R.; Kellman, D.H.

    1993-10-01

    The region between the pole faces of the DIII-D neutral beamline residual ion bending magnets is an area of transient high gas pressure which may cause beam defocusing and increased heating of beamline internal components due to collisional effects. An investigation of these effects helps in understanding residual ion trajectories and in providing information for studying in the beamline capability for operation with increased pulse duration. Examination of collisional effects, and of the possible existence of space charge blow-up, was carried out by injecting deuterium gas into the region between the magnet pole faces with rates varying from 0 to 18 torr-{ell}/sec. Thermocouple and waterflow calorimetry data were taken to measure the beamline component heating and beam powder deposition on the magnet pole shields, magnet louvers, ion dump, beam collimators, and calorimeter. Data was also taken at gas flow rates varying from 0 to 25 torr-{ell}/sec into the neutralizer cell and is compared with the magnet region gas injection data obtained. Results show that both collisional effects and space charge blow-up play a role in magnet region component heating and that neutralizer gas flow sufficiently reduces component heating without incurring unacceptable power losses through collisional effects.

  7. Suite of three protein crystallography beamlines with single superconducting bend magnet as the source

    SciTech Connect

    MacDowell, Alastair A.; Celestre, Richard S.; Howells, Malcolm; McKinney, Wayne; Krupnick, James; Cambie, Daniella; Domning, Edward E; Duarte, Robert M.; Kelez, Nicholas; Plate, David W.; Cork, Carl W.; Earnest, Thomas N.; Dickert, Jeffery; Meigs, George; Ralston, Corie; Holton, James M.; Alber, Thomas; Berger, James M.; Agard, David A.; Padmore, Howard A.

    2004-08-01

    At the Advanced Light Source (ALS), three protein crystallography (PX) beamlines have been built that use as a source one of the three 6 Tesla single pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single pole superconducting bend magnets enables the development of a hard x-ray program on a relatively low energy 1.9 GeV ring without taking up insertion device straight sections. The source is of relatively low power, but due to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.

  8. A novel topology for the bending magnets power supply at LNLS

    SciTech Connect

    Pomilio, J.A. ); Wisnivesky, D.; Lira, A.C. )

    1992-10-01

    The Synchrotron Radiation source under construction at the LNLS in Brazil is composed of 12 bending magnets and 3 quadrupole families. This paper reports on a new topology of high-performance dc current power supply developed to feed the magnets. The main goal is to get a high performance (mean current stability, tracking, repeatability and ripple better than 100 ppm), highly efficient and reliable system. To achieve these goals, a new power supply topology was developed based on a modular switched-mode power supply associated in series with a 6 pulse SCR bridge. To reduce possible high levels of electromagnetic interference, only a small fraction of the total load voltage is used to feed the SMPS; more than 90% of the power is delivered by the SCR bridge. Furthermore, the load current is shared among the SMPS modules, so that each one switches only a fraction of the total current.

  9. Directly water-cooled crystal development for SPring-8 bending magnet beamlines

    NASA Astrophysics Data System (ADS)

    Takeshita, Kunikazu; Goto, Shunji; Ishikawa, Tetsuya

    2007-09-01

    The directly water-cooled first crystal of the SPring-8 standard monochromator for bending magnet beamlines has been developed. Thanks to the bonding technique, the performance of the new crystal has been improved without decreasing the cooling efficiency. The finite element analyses show the deformation of the crystal by the hydraulic pressure and by the crystal clamping is negligible small, which were dominated for the previous crystal. Both Si(111) and Si(311) crystal were evaluated in SPring-8 beamlines, the deformation induced while the bonding process is comparable to the thermal deformation. and long-term endurance test shows the lifetime of the O-ring becomes long because they are not on the direct path of the SR beam. Although the overall performance is insufficient, much improvement was shown.

  10. Commissioning of horizontal-bend superconducting magnet for Jefferson Lab's 11-GeV super high momentum spectrometer

    DOE PAGESBeta

    Sun, Eric; Brindza, Paul D.; Lassiter, Steven R.; Fowler, Mike J.; Fenker, Howard C.; DeKamp, Jon C.

    2016-03-02

    Commissioning characteristics of the Superconducting High Momentum Spectrometer (SHMS) Horizontal Bend (HB) magnet was presented. Pre-commissioning peer review of the magnet uncovered issues with eddy currents in the thermal shield, resulting in additional testing and modeling of the magnet. A three-stage test plan was discussed. A solution of using a small dump resistor and a warm thermal shield was presented. Analyses illustrated that it was safe to run the magnet to full test current. As a result, the HB magnet was successfully cooled to 4 K and reached its maximum test current of 4000 A.

  11. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    NASA Astrophysics Data System (ADS)

    Gruszecki, P.; Romero-Vivas, J.; Dadoenkova, Yu. S.; Dadoenkova, N. N.; Lyubchanskii, I. L.; Krawczyk, M.

    2014-12-01

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

  12. Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

    SciTech Connect

    Gruszecki, P. Krawczyk, M.; Romero-Vivas, J.; Dadoenkova, Yu. S.; Dadoenkova, N. N.; Lyubchanskii, I. L.

    2014-12-15

    For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hänchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

  13. Control and Interlocking System for Bending Magnet Front-end at Indus-2

    SciTech Connect

    Kane, Sanjeev R.; Garg, Chander Kant; Nandedkar, R. V.

    2007-01-19

    We present control and interlock system developed for Indus-2 bending magnet front-end. The paper describes in detail the control of various signals associated with the front-end and the interlocking scheme implemented for the installed front-end. The number of signals associated with each front-end is {approx} 75. A control system is designed for monitoring temperature, pressure, airflow, water flow and control of vacuum gauges, fast shutter, water cooled shutter, safety shutter, pneumatic gate valves, sputter ion pump power supplies, beam position monitor etc. Two independent signals are generated for critical components that are used for software interlock and hard-wired interlock. The front-end control system is VME based and window 2000/XP workstation as an operator console. The CPU used is Motorola 68000-processor board of the VME bus having OS-9 real time operating system. One VME crate serves a cluster of 2-3 front ends. The communication between the VME and the workstation is linked over RS232 serial communication. The sputter ion power supplies are connected over isolated RS485 network. Critical protection features are implemented so that no single failure can render the system unsafe. This is implemented by providing two independent chains of protection (1) Hard wired in which relay logic is used and (2) Software. A Graphical User Interface (GUI) is developed using Lab view Version 7.0.

  14. Bending strain-tunable magnetic anisotropy in Co2FeAl Heusler thin film on KaptonxAE

    NASA Astrophysics Data System (ADS)

    Gueye, M.; Wague, B. M.; Zighem, F.; Belmeguenai, M.; Gabor, M. S.; Petrisor, T.; Tiusan, C.; Mercone, S.; Faurie, D.

    2014-08-01

    Bending effect on the magnetic anisotropy in 20 nm Co2FeAl Heusler thin film grown on Kapton® has been studied by ferromagnetic resonance and glued on curved sample carrier with various radii. The results reported in this Letter show that the magnetic anisotropy is drastically changed in this system by bending the thin films. This effect is attributed to the interfacial strain transmission from the substrate to the film and to the magnetoelastic behavior of the Co2FeAl film. Moreover, two approaches to determine the in-plane magnetostriction coefficient of the film, leading to a value that is close to λCFA= 14 × 10-6, have been proposed.

  15. A new bend magnet beam line for scanning transmission x-ray microscopy at the Advanced Light Source

    SciTech Connect

    Warwick, Tony; Ade, Harald; Kilcoyne, A.L. David; Kritscher, Michael; Tylisczcak, Tolek; Fakra, Sirine; Hitchcock, Adam P.; Hitchcock, Peter; Padmore, Howard A.

    2001-12-12

    The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a Scanning Transmission X-ray Microscope (STXM). This is the first diffraction-limited scanning x-ray microscope to operate with useful count rate on a synchrotron bend magnet source. A simple, dedicated beam line has been built covering the range of photon energy from 250 eV to 600 eV. Ease of use and operational availability are radically improved compared to previous installations using undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near edge x-ray absorption spectro-microscopy with a spectral resolution up to about 1:5000 and with STXM count rates in excess of 1 MHz.

  16. Justification for the development of a bending magnet beamline at sector 10 at the APS.

    SciTech Connect

    Kemner, K. M.; Biosciences Division

    2006-09-18

    The long-planned and much-needed merger of EnviroCAT into the Materials Research Collaborative Access Team (MR-CAT) will provide dedicated state-of-the-art facilities that are critical to research on a broad range of issues in environmental sciences. These CATs will focus on developing a bending magnet (BM) beamline for x-ray absorption fine structure (XAFS) and micro x-ray analysis of environmental samples through integration with existing insertion device (ID) capabilities in XAFS, micro x-ray analysis, and x-ray scattering. In addition, the expanded MR-CAT will serve as the hub of personnel and laboratory infrastructure support for molecular environmental science and biogeochemical science at the Advanced Photon Source (APS). In conjunction with the merger of EnviroCAT into MR-CAT, the US Environmental Protection Agency (EPA) will become a member institution of MR-CAT, joining the present members (University of Notre Dame, Illinois Institute of Technology, University of Florida, British Petroleum, and Argonne's Chemical Engineering and Biosciences Division). The motivation for blending capabilities meeting the needs of EnviroCAT users into the MR-CAT facilities is the explosion of synchrotron-radiation-based research in the field known as molecular environmental science (MES). This research is driven largely by the need to remediate contaminated environmental materials and to understand the scientific foundations that govern contaminant transport in the environment. Synchrotron radiation is playing a crucial role in solving environmental science problems by offering x-ray-based analytical techniques for detailed molecular- and atomic-level studies of these systems. This document focuses on the scientific justification for developing a specific type of BM beamline capability at Sector 10 for XAFS and micro x-ray analysis to support the growing MES community. However, the modification of Sector 10 will meet other future needs by providing (1) an existing undulator

  17. Computer studies of a combined-function bend magnet for a proposed redesign of the SLAC SLC damping rings

    SciTech Connect

    Early, R.A.; Raubenheimer, T.O.

    1993-04-01

    A proposed redesign of the SLAC SLC Damping Ring requires a combined-function bending magnet. The magnet will operate with a main field of 1.8338 T, and quadrupole and sextupole gradients dB{sub y}/dx, d{sup 2}B{sub y}/dx{sup 2} of {minus}14.1 T/m and {minus}477 T/m{sup 2}, respectively. Because the orbit sagitta in the magnet is in excess of 2 cm, the pole will be curved with a 2 m radius of curvature. Furthermore, since the current must be variable over a range of {plus_minus}2 percent, we have considered using vanadium permendur poles to avoid a adverse saturation effects. Studies were done using POISSON in 2-D and TOSCA for 3-D end effects.

  18. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  19. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  20. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  1. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  2. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  3. Relaxation of bending stresses and the reversibility of residual stresses in amorphous soft magnetic alloys

    SciTech Connect

    Kekalo, I. B.; Mogil’nikov, P. S.

    2015-06-15

    The reversibility of residual bending stresses is revealed in ribbon samples of cobalt- and iron-based amorphous alloys Co{sub 69}Fe{sub 3.7}Cr{sub 3.8}Si{sub 12.5}B{sub 11} and Fe{sub 57}Co{sub 31}Si{sub 2.9}B{sub 9.1}: the ribbons that are free of applied stresses and bent under the action of residual stresses become completely or incompletely straight upon annealing at the initial temperatures. The influence of annealing on the relaxation of bending stresses is studied. Preliminary annealing is found to sharply decrease the relaxation rate of bending stresses, and the initial stage of fast relaxation of these stresses is absent. Complete straightening of preliminarily annealed ribbons is shown to occur at significantly higher temperatures than that of the initial ribbons. Incomplete straightening of the ribbons is explained by the fact that bending stresses relaxation at high annealing temperatures proceeds due to both reversible anelastic deformation and viscous flow, which is a fully irreversible process. Incomplete reversibility is also caused by irreversible processes, such as the release of excess free volume and clustering (detected by small-angle X-ray scattering). The revealed differences in the relaxation processes that occur in the cobalt- and iron-based amorphous alloys are discussed in terms of different atomic diffusion mobilities in these alloys.

  4. Design and Fabrication of the Superconducting Horizontal Bend Magnet for the Super High Momentum Spectrometer at Jefferson Lab

    SciTech Connect

    Chouhan, Shailendra S.; DeKamp, Jon; Burkhart, E. E,; Bierwagen, J.; Song, H.; Zeller, Albert F.; Brindza, Paul D.; Lassiter, Steven R.; Fowler, Michael J.; Sun, Qiuli

    2015-06-01

    A collaboration exists between NSCL and JLab to design and build JLab's Super High Momentum Spectrometer (SHMS) horizontal bend magnet that allows the bending of the 12 GeV/c particles horizontally by 3° to allow SHMS to reach angles as low as 5.5°. Two full size coils have been wound and are cold tested for both magnetic and structural properties. Each coil is built from 90 layers of single-turn SSC outer conductor cable. An initial test coil with one third the turns was fabricated to demonstrate that the unique saddle shape with fully contoured ends could be wound with Rutherford superconducting cable. Learned lessons during the trial winding were integrated into the two complete full-scale coils that are now installed in the helium vessel. The fabrication of the iron yoke, cold mass, and thermal shield is complete, and assembly of the vacuum vessel is in progress. This paper presents the process and progress along with the modified magnet design to reduce the fringe field in the primary beam region and also includes the impact of the changes on coil forces and coil restraint system.

  5. An ion-optical design study of a carbon-ion rotating gantry with a superconducting final bending magnet

    NASA Astrophysics Data System (ADS)

    Bokor, J.; Pavlovič, M.

    2016-03-01

    Ion-optical designs of an isocentric ion gantry with a compact curved superconducting final bending magnet are presented. The gantry is designed for transporting carbon-therapy beams with nominal kinetic energy of 400 MeV/u, which corresponds to the penetration range of C6+ beam in water of about 28 cm. In contrast to other existing designs, we present a "hybrid" beam transport system containing a single superconducting element - the last bending magnet. All other elements are based on conventional warm technology. Ion-optical properties of such a hybrid system are investigated in case of transporting non-symmetric (i.e. different emittance patterns in the horizontal and vertical plane) beams. Different conditions for transporting the non-symmetric beams are analyzed aiming at finding the optimal, i.e. the most compact, gantry version. The final gantry layout is presented including a 2D parallel scanning. The ion-optical and scanning properties of the final gantry design are described, discussed and illustrated by computer simulations performed by WinAGILE.

  6. A finite element analysis of room temperature silicon crystals for the advanced photon source bending-magnet and insertion-device beams

    SciTech Connect

    Assoufid, L.; Lee, W.K.; Mills, D.

    1994-10-01

    In this paper, we give the results of a series of thermal and distortion finite element analyses performed on room temperature silicon for the three standard APS sources, namely, the bending magnet, Wiggler A, and Undulator A. The modeling was performed with the silicon cooled directly with water or liquid gallium through rectangular channels.

  7. A finite element analysis of room-temperature silicon crystals for the advanced photon source bending-magnet and insertion-device beams

    SciTech Connect

    Assoufid, L.; Lee, W.; Mills, D.M. )

    1995-03-01

    In this paper, the results of a series of thermal and distortion finite element analyses performed on room-temperature silicon for the three standard APS sources, namely, the bending magnet, wiggler A, and undulator A, are reported. The modeling was performed with the silicon cooled directly with water or liquid gallium through rectangular channels.

  8. A finite element analysis of room-temperature silicon crystals for the advanced photon source bending-magnet and insertion-device beams (abstract)

    SciTech Connect

    Assoufid, L.; Lee, W.; Mills, D.M. )

    1995-02-01

    In this paper, the results of a series of thermal and distortion finite element analyses performed on room-temperature silicon for the three standard APS sources, namely, the bending magnet, wiggler A, and undulator A, are reported. The modeling was performed with the silicon cooled directly with water or liquid gallium through rectangular channels.

  9. Beamline 9.3.2 - a high-resolution, bend-magnet beamline with circular polarization capability

    SciTech Connect

    Moler, E.J.; Hussain, Z.; Howells, M.R.

    1997-04-01

    Beamline 9.3.2 is a high resolution, SGM beamline on an ALS bending magnet with access to photon energies from 30-1500 eV. Features include circular polarization capability, a rotating chamber platform that allows switching between experiments without breaking vacuum, an active feedback system that keeps the beam centered on the entrance slit of the monochromator, and a bendable refocusing mirror. The beamline optics consist of horizontally and vertically focussing mirrors, a Spherical Grating Monochromator (SGM) with movable entrance and exit slits, and a bendable refocussing mirror. In addition, a movable aperature has been installed just upstream of the vertically focussing mirror which can select the x-rays above or below the plane of the synchrotron storage ring, allowing the user to select circularly or linearly polarized light. Circularly polarized x-rays are used to study the magnetic properties of materials. Beamline 9.3.2 can supply left and right circularly polarized x-rays by a computer controlled aperture which may be placed above or below the plane of the synchrotron storage ring. The degree of linear and circular polarization has been measured and calibrated.

  10. Passive, achromatic, nearly isochronous bending system

    DOEpatents

    Douglas, David R.; Yunn, Byung C.

    2004-05-18

    A particle beam bending system having a geometry that applies active bending only beyond the chord of the orbit for any momentum component. Using this bending configuration, all momentum components emerge dispersed in position only; all trajectories are parallel by construction. Combining a pair of such bends with reflective symmetry produces a bend cell that is, by construction, achromatic to all orders. By the particular choice of 45.degree. individual bends, a pair of such achromats can be used as the basis of a 180.degree. recirculation arc. Other rational fractions of a full 180.degree. bend serve equally well (e.g., 2 bends/cell.times.90.degree./bend.times.1 cell /arc; 2 bends/cell.times.30.degree./bend.times.3 cells/arc, etc), as do combinations of multiple bending numerologies (e.g., 2 bends/cell.times.22.5.degree./bend.times.2 cells+2 bends/cell.times.45.degree./bend.times.1 cell). By the choice of entry pole face rotation of the first magnet and exit pole face rotation of the second magnet (with a value to be determined from the particular beam stability requirements imposed by the choice of bending angle and beam properties to be used in any particular application), desirable focusing properties can be introduced and beam stability can be insured.

  11. Polycapillary-optics-based micro-XANES and micro-EXAFS at a third-generation bending-magnet beamline.

    PubMed

    Silversmit, Geert; Vekemans, Bart; Nikitenko, Sergey; Bras, Wim; Czhech, Viktoria; Zaray, Gyula; Szaloki, Imre; Vincze, Laszlo

    2009-03-01

    A focusing system based on a polycapillary half-lens optic has been successfully tested for transmission and fluorescence micro-X-ray absorption spectroscopy at a third-generation bending-magnet beamline equipped with a non-fixed-exit Si(111) monochromator. The vertical positional variations of the X-ray beam owing to the use of a non-fixed-exit monochromator were shown to pose only a limited problem by using the polycapillary optic. The expected height variation for an EXAFS scan around the Fe K-edge is approximately 200 microm on the lens input side and this was reduced to approximately 1 microm for the focused beam. Beam sizes (FWHM) of 12-16 microm, transmission efficiencies of 25-45% and intensity gain factors, compared with the non-focused beam, of about 2000 were obtained in the 7-14 keV energy range for an incoming beam of 0.5 x 2 mm (vertical x horizontal). As a practical application, an As K-edge micro-XANES study of cucumber root and hypocotyl was performed to determine the As oxidation state in the different plant parts and to identify a possible metabolic conversion by the plant. PMID:19240336

  12. Polycapillary based μ-XAS and confocal μ-XANES at a bending magnet source of the ESRF

    NASA Astrophysics Data System (ADS)

    Silversmit, Geert; Vekemans, Bart; Nikitenko, Sergey; Tirez, Kristof; Bras, Wim; Brenker, Frank E.; Vincze, Laszlo

    2009-11-01

    Glass polycapillary optics are shown to be easy to use focusing optics for bending magnet XAS stations. These achromatic optics have acceptances of several mm horizontally and vertically, while their angular acceptances can be matched to the source divergence by the design of the polycapillary. A polycapillary half-lens based focusing system was successfully tested for transmission and fluorescence μ-XAS at the DUBBLE beamline (BM26A, ESRF) and the feasibility of confocal μ-XANES in fluorescence mode is presented. Transmission efficiencies of 25-45% with flux density gain factors of about 2000 and beam sizes of 10-20 μm were obtained in the 7-14 keV energy range. Although the polycapillary optic has a smoothly changing energy dependent transmission efficiency, the amplitude and shape of the EXAFS oscillations are not influenced by this. The focusing properties of the polycapillary lens cancel slight vertical motions of the incoming X-ray beam, resulting in a fixed μ-beam spot in the focal plane, making polycapillaries also suitable optic in combination with a non-fixed exit monochromator. In addition, by mounting a second polycapillary half-lens in front of an energy dispersive detector, a confocal set-up is obtained, which restricts the part of the sample seen by the detector to a microscopic volume of about 20×20×15 μm3 at the Fe K absorption edge for example.

  13. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    NASA Astrophysics Data System (ADS)

    Sutter, John P.; Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-01

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  14. A BEAMLINE FOR HIGH PRESSURE STUDIES AT THE ADVANCED LIGHT SOURCE WITH A SUPERCONDUCTING BENDING MAGNET AS THE SOURCE

    SciTech Connect

    Kunz, M; MacDowell, A A; Caldwell, W A; Cambie, D; Celestre, R S; Domning, E E; Duarte, R M; Gleason, A; Glossinger, J; Kelez, N; Plate, D W; Yu, T; Zaug, J M; Padmore, H A; Jeanloz, R; Alivisatos, A P; Clark, S M

    2005-04-19

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/{Delta}E {approx} 7000) and a W/B{sub 4}C multilayer (E/{Delta}E {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.

  15. A Beamline for High-Pressure Studies at the Advanced Light Sourcewith a Superconducting Bending Magnet as the Source

    SciTech Connect

    Kunz, Martin; MacDowell, Alastair A.; Caldwell, Wendel A.; Cambie, Daniella; Celestre, Richard S.; Domning, Edward E.; Duarte,Robert M.; Gleason, Arianna E.; Glossinger, James M.; Kelez, Nicholas; Plate, David W.; Yu, Tony; Zaug, Joeseph M.; Padmore, Howard A.; Jeanloz,Raymond; Alivisatos, A. Paul; Clark, Simon M.

    2005-06-30

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/DE {approx}7000) and a W/B4C multilayers (E/DE {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.

  16. A beamline for high-pressure studies at the Advanced Light Source with a superconducting bending magnet as the source.

    PubMed

    Kunz, Martin; MacDowell, Alastair A; Caldwell, Wendel A; Cambie, Daniella; Celestre, Richard S; Domning, Edward E; Duarte, Robert M; Gleason, Arianna E; Glossinger, James M; Kelez, Nicholas; Plate, David W; Yu, Tony; Zaug, Joeseph M; Padmore, Howard A; Jeanloz, Raymond; Alivisatos, A Paul; Clark, Simon M

    2005-09-01

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 T superconducting bending magnet (superbend). Useful X-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness-preserving optics of the beamline. These optics are comprised of a plane parabola collimating mirror, followed by a Kohzu monochromator vessel with Si(111) crystals (E/DeltaE approximately equal 7000) and W/B4C multilayers (E/DeltaE approximately equal 100), and then a toroidal focusing mirror with variable focusing distance. The experimental enclosure contains an automated beam-positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detector (CCD or image-plate detector). Future developments aim at the installation of a second endstation dedicated to in situ laser heating and a dedicated high-pressure single-crystal station, applying both monochromatic and polychromatic techniques. PMID:16120990

  17. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    SciTech Connect

    Sutter, John P. Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-28

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  18. eMBI: Boosting Gene Expression-based Clustering for Cancer Subtypes.

    PubMed

    Chang, Zheng; Wang, Zhenjia; Ashby, Cody; Zhou, Chuan; Li, Guojun; Zhang, Shuzhong; Huang, Xiuzhen

    2014-01-01

    Identifying clinically relevant subtypes of a cancer using gene expression data is a challenging and important problem in medicine, and is a necessary premise to provide specific and efficient treatments for patients of different subtypes. Matrix factorization provides a solution by finding checker-board patterns in the matrices of gene expression data. In the context of gene expression profiles of cancer patients, these checkerboard patterns correspond to genes that are up- or down-regulated in patients with particular cancer subtypes. Recently, a new matrix factorization framework for biclustering called Maximum Block Improvement (MBI) is proposed; however, it still suffers several problems when applied to cancer gene expression data analysis. In this study, we developed many effective strategies to improve MBI and designed a new program called enhanced MBI (eMBI), which is more effective and efficient to identify cancer subtypes. Our tests on several gene expression profiling datasets of cancer patients consistently indicate that eMBI achieves significant improvements in comparison with MBI, in terms of cancer subtype prediction accuracy, robustness, and running time. In addition, the performance of eMBI is much better than another widely used matrix factorization method called nonnegative matrix factorization (NMF) and the method of hierarchical clustering, which is often the first choice of clinical analysts in practice. PMID:25374455

  19. Effect of bending stresses on the high-frequency magnetic properties and their time stability in a cobalt-based amorphous alloy with an extremely low magnetostriction

    NASA Astrophysics Data System (ADS)

    Kekalo, I. B.; Mogil'nikov, P. S.

    2015-12-01

    An unusual effect of the stresses of bending (toroidal sample diameter D) on the hysteretic magnetic properties ( H c , μ5) of an amorphous Co69Fe3.7Cr3.8Si12B11 alloy with an extremely low magnetostriction (|λ s | ≤ 10-7) is revealed. These properties are measured in a dynamic regime at a magnetic-field frequency f = 0.1-20 kHz. The coercive force of the alloy H c weakly depends on D at low frequencies ( f < 1 kHz), and permeability μ5 ( H = 5 mOe), in contrast, is independent of D at high frequencies and is dependent on D at low frequencies. The samples subjected to high-temperature (390°C) annealing followed by water quenching exhibit "anomalous" dependences: permeability μ5 increases with decreasing toroidal sample radius, i.e., with increasing bending stresses. The detected dependences are related to the fact that magnetization reversal via the displacement of rigid domain walls is predominant at low frequencies and during static measurements and magnetization reversal via the displacement of flexible domain walls is predominant at high frequencies.

  20. Liquid-metal-cooled, curved-crystal monochromator for Advanced Photon Source bending-magnet beamline 1-BM

    SciTech Connect

    Brauer, S.; Rodricks, B.; Assoufid, L.; Beno, M.A.; Knapp, G.S.

    1996-06-01

    The authors describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5--20 keV range, with a predicted focal spot size of {le} 100 {micro}m. To minimize thermal distortions and thermal equilibration time, the 355 x 32 x 0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed.

  1. Liquid-metal-cooled curved-crystal monochromator for Advanced Photon Source bending-magnet beamline 1-BM

    SciTech Connect

    Brauer, S.; Rodricks, B.; Assoufid, L.; Beno, M.; Knapp, G.

    1996-09-01

    We describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5{endash}20 keV range, with a predicted focal spot size of {le}100 {mu}m. To minimize thermal distortions and thermal equilibration time, the 355{times}32{times}0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed. {copyright} {ital 1996 American Institute of Physics.}

  2. The millimeter-wave bolometric interferometer (MBI) for observing the cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Kim, Jaiseung

    This thesis describes the Millimeter-wave Bolometric Interferometer (MBI) to measure the Cosmic Microwave Background Polarization (CMBP) anisotropy at angular scales 0.5°--1° and a center frequency of 90 GHz. The measurement of the CMBP anisotropy on these angular scales will put more stringent constraints on cosmological models and parameters. The prototype instrument employs four corrugated feedhorns and cooled bolometers. Using a Butler beam combiner, beams from four feedhorns are correlated, yielding interferometric measurements of the CMBP. From these interferometric measurements, we can reconstruct the image of polarization by aperture synthesis and estimate the power spectrum of the CMBP by maximum likelihood method. We describe aperture synthesis and maximum likelihood method. We present the result of the image reconstruction and the power spectrum estimation from simulated MBI observations. With the planned sensitivity of the MBI, the MBI will be able to estimate the E mode power spectra of the CMBP in the multipole range (150 <= l <= 300) and put upper bounds on the B mode power spectra in the relevant multipoles. In the end, we describe all-sky imaging method from interferometric measurements developed for the Einstein Probe Interferometer for Cosmology (EPIC), which is the satellite version of the MBI.

  3. Stress-anneal-induced magnetic anisotropy in highly textured Fe-Ga and Fe-Al magnetostrictive strips for bending-mode vibrational energy harvesters

    NASA Astrophysics Data System (ADS)

    Park, Jung Jin; Na, Suok-Min; Raghunath, Ganesh; Flatau, Alison B.

    2016-05-01

    Magnetostrictive Fe-Ga and Fe-Al alloys are promising materials for use in bending-mode vibrational energy harvesters. For this study, 50.8 mm × 5.0 mm × 0.5 mm strips of Fe-Ga and Fe-Al were cut from 0.50-mm thick rolled sheet. An atmospheric anneal was used to develop a Goss texture through an abnormal grain growth process. The anneal lead to large (011) grains that covered over 90% of sample surface area. The resulting highly-textured Fe-Ga and Fe-Al strips exhibited saturation magnetostriction values (λsat = λ∥ - λ⊥) of ˜280 ppm and ˜130 ppm, respectively. To maximize 90° rotation of magnetic moments during bending of the strips, we employed compressive stress annealing (SA). Samples were heated to 500°C, and a 100-150 MPa compressive stress was applied while at 500°C for 30 minutes and while being cooled. The effectiveness of the SA on magnetic moment rotation was inferred by comparing post-SA magnetostriction with the maximum possible yield of rotated magnetic moments, which is achieved when λ∥ = λsat and λ⊥ = 0. The uniformity of the SA along the sample length and the impact of the SA on sensing/energy harvesting performance were then assessed by comparing pre- and post-SA bending-stress-induced changes in magnetization at five different locations along the samples. The SA process with a 150 MPa compressive load improved Fe-Ga actuation along the sample length from 170 to 225 ppm (from ˜60% to within ˜80% of λsat). The corresponding sensing/energy harvesting performance improved by as much as a factor of eight in the best sample, however the improvement was not at all uniform along the sample length. The SA process with a 100 MPa compressive load improved Fe-Al actuation along the sample length from 60 to 73 ppm (from ˜46% to ˜56% of λsat, indicating only a marginally effective SA and suggesting the need for modification of the SA protocol. In spite of this, the SA was effective at improving the sensing/energy harvesting

  4. The time-resolved and extreme conditions XAS (TEXAS) facility at the European Synchrotron Radiation Facility: the general-purpose EXAFS bending-magnet beamline BM23

    PubMed Central

    Mathon, O.; Beteva, A.; Borrel, J.; Bugnazet, D.; Gatla, S.; Hino, R.; Kantor, I.; Mairs, T.; Munoz, M.; Pasternak, S.; Perrin, F.; Pascarelli, S.

    2015-01-01

    BM23 is the general-purpose EXAFS bending-magnet beamline at the ESRF, replacing the former BM29 beamline in the framework of the ESRF upgrade. Its mission is to serve the whole XAS user community by providing access to a basic service in addition to the many specialized instruments available at the ESRF. BM23 offers high signal-to-noise ratio EXAFS in a large energy range (5–75 keV), continuous energy scanning for quick-EXAFS on the second timescale and a micro-XAS station delivering a spot size of 4 µm × 4 µm FWHM. It is a user-friendly facility featuring a high degree of automation, online EXAFS data reduction and a flexible sample environment. PMID:26524321

  5. A finite element analysis of room temperature silicon crystals for the Advanced Photon Source bending-magnet and insertion-device beams

    SciTech Connect

    Assoufid, L.; Lee, W.K.; Mills, D.M.

    1994-08-01

    The third generation of synchrotron radiation sources, such as the Advanced Photon Source (APS), will provide users with a high brilliance x-ray beam with high power and power densities. In many cases, the first optical component to intercept the x-ray beam is a silicon-crystal monochromator. Due to extreme heat loading, the photon throughput and brilliance will be severely degraded if the monochromator is not properly designed (or cooled). This document describes a series of finite element analyses performed on room temperature silicon for the three standard APS sources, namely, the bending magnet, Wiggler A, and Undulator A. The modeling is performed with the silicon cooled directly with water or liquid gallium through rectangular channels. The temperature distributions and thermally induced deformations are presented.

  6. Discursive Modes and Their Pedagogical Functions in Model-Based Inquiry (MBI) Classrooms

    ERIC Educational Resources Information Center

    Campbell, Todd; Oh, Phil Seok; Neilson, Drew

    2012-01-01

    This research investigated the emergent discursive modes and their pedagogical functions found in model-based inquiry (MBI) science classrooms. A sample of four high school physics classrooms was video-recorded and analysed using a newly established discourse mode analysis framework. Qualitative methods were employed to identify the most salient…

  7. The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric interferometer (MBI)

    NASA Astrophysics Data System (ADS)

    Timbie, P. T.; Tucker, G. S.; Ade, P. A. R.; Ali, S.; Bierman, E.; Bunn, E. F.; Calderon, C.; Gault, A. C.; Hyland, P. O.; Keating, B. G.; Kim, J.; Korotkov, A.; Malu, S. S.; Mauskopf, P.; Murphy, J. A.; O'Sullivan, C.; Piccirillo, L.; Wandelt, B. D.

    2006-12-01

    We provide an overview of a mission concept study underway for the Einstein Inflation Probe (EIP). Our study investigates the advantages and tradeoffs of using an interferometer (EPIC) for the mission. We also report on the status of the millimeter-wave bolometric interferometer (MBI), a ground-based pathfinder optimized for degree-scale CMB polarization measurements at 90 GHz.

  8. Discursive Modes and Their Pedagogical Functions in Model-Based Inquiry (MBI) Classrooms

    NASA Astrophysics Data System (ADS)

    Campbell, Todd; Oh, Phil Seok; Neilson, Drew

    2012-10-01

    This research investigated the emergent discursive modes and their pedagogical functions found in model-based inquiry (MBI) science classrooms. A sample of four high school physics classrooms was video-recorded and analysed using a newly established discourse mode analysis framework. Qualitative methods were employed to identify the most salient types and sequences of discursive modes and to interpret their pedagogical functions in the context of MBI. Results indicated that exploring was one of the most frequently used discursive modes in the MBI classrooms. Sometimes two different types of exploring discourse were connected sequentially so that the pattern of exploring (scientific phenomena)-exploring (student ideas) appeared. The discursive sequences of exploring-retrieving and exploring-negotiating also emerged whereby the teacher guided students to align their models with the canonical knowledge of science. The teacher also helped students in modelling using elaborating and reformulating discourse modes as well as metadiscourse. Although the MBI classes were implemented in a manner similar to teacher-guided inquiry, it was also observed that students participated actively in several discursive practices. Implications for model- or modelling-based science instruction and science education research were discussed.

  9. CSR IMPEDANCE DUE TO A BEND MAGNET OF FINITE LENGTH WITH A VACUUM CHAMBER OF RECTANGULAR CROSS SECTION

    SciTech Connect

    Stupakov, G.; Kotelnikov, I.A.; /Novosibirsk State U.

    2009-06-05

    We study the impedance due to coherent synchrotron radiation (CSR) generated by a short bunch of charged particles passing through a dipole magnet of finite length in a vacuum chamber of a given cross section. Our method represents a further development of the previous studies: we decompose the electromagnetic field of the beam over the eigenmodes of the toroidal chamber and derive a system of equations for the expansion coefficients in the series. We illustrate our general method by calculating the CSR impedance of a beam moving in a toroidal vacuum chamber of rectangular cross section.

  10. Reversal bending fatigue testing

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Tan, Ting

    2014-10-21

    Embodiments for apparatuses for testing reversal bending fatigue in an elongated beam are disclosed. Embodiments are configured to be coupled to first and second end portions of the beam and to apply a bending moment to the beam and create a pure bending condition in an intermediate portion of the beam. Embodiments are further configured to cyclically alternate the direction of the bending moment applied to the beam such that the intermediate portion of the beam cyclically bends in opposite directions in a pure bending condition.

  11. Sub-micron spatial resolution of a micro-XAFS electrostatic microscope with bending magnet radiation: Performance assessments and prospects for aberration correction

    NASA Astrophysics Data System (ADS)

    Tonner, B. P.; Dunham, D.

    1994-08-01

    The X-ray photoemission electron microscope (XPEEM) has been shown to be a valuable tool for small-area X-ray absorption fine-structure (XAFS) spectroscopy, and for state-selected imaging. The instrument currently in regular operation on bending-magnet monochromators uses electrostatic optics to create an image of a sample surface in vacuum. The instrument can be operated on a wide variety of X-ray and VUV beamlines, and the spectral resolution is determined by the beamline monochromator. The spatial resolution is determined primarily by the aberrations of the immersion lens accelerating field and the objective lens, although other factors such as surface roughness play an important, though less fundamental role. We have tested the spatial resolution of micro-XAFS with a high quality test object, consisting of a free-standing circular zone plate made of gold. These tests confirm the assessment that chromatic aberration limits the performance of the optics, because of the wide range of kinetic energies of secondary electrons produced in XAFS spectroscopy, and the highly asymmetric intensity distribution of these secondaries. One attempt at solving the chromatic aberration problem is the use of an energy filter, which solves the problem by allowing only a narrow band of electrons to produce an image. We describe an alternative approach, based on chromatic aberration correction, which has great potential for an XPEEM instrument with extremely high transmission, and spatial resolution below 10 nm. We also point out the performance improvements to be expected when XPEEM is adapted to high-throughput undulator beamlines.

  12. Divertor Experiments with MBI and Strong Gas Puffing on HL-2A

    NASA Astrophysics Data System (ADS)

    Duan, Xuru; Ding, Xuantong; Yang, Qingwei; Yan, Longwen; Yao, Lianghua; Hong, Wenyu; Xuan, Weimin; Liu, Dequan; Chen, Liaoyuan; Song, Xianming; Zhang, Jinhua; Cao, Zeng; Cui, Zhengying; Li, Wei; Liu, Yi; Pan, Yudong; Pan, Li; Zheng, Yinjia; Zhou, Yan; Mao, Weicheng; Liu, Yong; HL-2A Team

    2006-01-01

    In the HL-2A 2004 experiment campaign, pulsed molecular beam injection (MBI) and strong hydrogen gas puffing under the divertor configuration were used for gas fueling. The experimental results show that the MBI of hydrogen can reduce the heat flux to the divertor target plate. The electron temperature measured by the Langmuir probe array decreases significantly during the injection of the molecular beam whereas the electron density increases. This indicates that the plasma pressure near the target plates tends to be constant at a new equilibrium level. In the divertor plasmas with strong hydrogen gas puffing a high plasma density up to 4.4 × 1019 m-3 was achieved. In addition, a phenomenon similar to the partially detached divertor regime was observed, which is being studied in open divertor tokamaks such as DIII-D to reduce the peak heat flux on the target plates near the separatrix. After a strong gas puffing the electron temperature measured on the outer divertor target plate near the separatrix decreases till below 5 eV or even lower, but that of the farther outer divertor target plate does not change obviously; and the CIII and the Hα emissions at the plasma edge decrease as expected, but the Hα emission near the X-point increases. These results reflects some interesting characteristics, which needs to be studied by further modeling and experiments.

  13. Microhole Tubing Bending Report

    DOE Data Explorer

    Oglesby, Ken

    2012-01-01

    A downhole tubing bending study was made and is reported herein. IT contains a report and 2 excel spreadsheets to calculate tubing bending and to estimate contact points of the tubing to the drilled hole wall (creating a new support point).

  14. Discovering Gee's Bend Quilts

    ERIC Educational Resources Information Center

    Johnson, Ann

    2008-01-01

    Gee's Bend is a small community near Selma, Alabama where cotton plantations filled the land before the Civil War. After the war, the freed slaves of the plantations worked as tenant farmers and founded an African-American community. In 2002, the women of this community brought international attention and acclaim to Gee's Bend through the art of…

  15. MBI facility at BESSY II for time-resolved pump-probe techniques with laser and undulator radiation

    NASA Astrophysics Data System (ADS)

    Gatzke, Johannes; Winter, Bernd J.; Quast, T.; Hertel, Ingolf V.

    1998-10-01

    The MBI develops a facility at BESSY II dedicated to pump- probe techniques combining synchrotron and laser radiation. The synchronization of laser and synchrotron pulses will allow time resolved experiments on the picosecond time scale at this. The features of the facility, the optical parameters of the synchrotron beamline, the synchronization technique and pulse stretching considerations will be outlined. Current developments will be reported.

  16. Alpha effect due to magnetic buoyancy instability of a horizontal magnetic layer

    NASA Astrophysics Data System (ADS)

    Chatterjee, Piyali

    In this paper we study the hydromagnetic instability of a toroidal magnetic layer such as that thought to be located in the solar tachocline. The magnetic layer is located in a convectively stable layer and is subject to what is known as the magnetic buoyancy instability (MBI) and under suitable conditions breaks up into twisted and arching magnetic flux tubes. The MBI gives rise to an anti-quenched α effect which can be measured by using the sophisticated quasi-kinematic test field method. This paper aims at summarizing the main results of a much longer paper by Chatterjee et al. 2011, A&A (in press).

  17. Simulation of the performance of the Millimetre-Wave Bolometric Interferometer (MBI) for cosmic microwave background observations

    NASA Astrophysics Data System (ADS)

    Calderon, Carolina

    The Millimetre-wave Bolometric Interferometer (MBI) is a four element interferometer sensitive to polarisation, designed to measure the faint Cosmic Microwave Background anisotropics. MBI's new approach attempts to use the advantages of interferometry and the high sensitivity of bolometers in order to be able to measure the primordial B mode signal in subsequent versions of MBI. This thesis presents novel methods for simulating the performance of MBI, and assesses how well the instrument will be able to measure the Cosmic Microwave Background (CMB) power spectrum. These methods can be used to make improvements in the design of future MBI versions. Many of these simulations have taken advantage of a scattering matrix approach, in which ideal or measured scattering matrices can be used. This allows to accurately simulate the noise at the detectors, in conjunction with other scattering matrices approaches, in order to describe the phonon noise from the sky and the instrument itself simultaneously. Together with known data analysis theory, the expected estimates, error bars and mixing have been derived for both ideal and non-ideal situations where systematic errors were present. Results show no significant correlation between noise at different detectors, and suggest that noise at the detectors is overestimated when the traditional photon NEP formula is used, as opposed to the method described here. This matter should be taken into account in future experiments where phonon noise is the dominant detector noise, since the phonon NEP can be reduced to the level of the photon noise by modifying the bolometers conductance. The band power window functions of MBI showed a lot of mixing between the bands, much more than that found in a single baseline interferometer measuring both Q and U. The error bars were also affected by the fact that the derivatives of the covariance matrix with respect to the band powers were very similar. The only significant systematic errors were

  18. Modeling of magnetostrictive Galfenol sensor and validation using four point bending test

    SciTech Connect

    Datta, Supratik; Atulasimha, Jayasimha; Flatau, Alison B.

    2007-05-01

    A magnetomechanical bending model has been developed to predict the magnetic induction, elastic, and magnetostrictive strain and bending stress in a magnetostrictive member subjected simultaneously to bending load and dc magnetic bias field. This model was obtained by coupling Euler-Bernoulli beam theory with an energy-based statistical model. The bending model predictions were within 10% of the experimental results obtained from a uniquely devised four point bending test of Galfenol (nominal composition of 84 at. % Fe and 16 at. % Ga) performed under different magnetic bias fields.

  19. Dispersion suppressors with bending

    SciTech Connect

    Garren, A.

    1985-10-01

    Dispersion suppressors of two main types are usually used. In one the cell quadrupole focussing structure is the same as in normal cells but some of the dipoles are replaced by drifts. In the other, the quadrupole strengths and/or spacings are different from those of the normal cells, but the bending is about the same as it is in the cells. In SSC designs to date, dispersion suppressors of the former type have been used, consisting of two cells with bending equivalent to one. In this note a suppressor design with normal bending and altered focussing is presented. The advantage of this scheme is that circumference is reduced. The disadvantages are that additional special quadrupoles must be provided (however, they need not be adjustable), and the maximum beta values within them are about 30% higher than the cell maxima.

  20. Right-angle slot waveguide bends with high bending efficiency.

    PubMed

    Ma, Changbao; Zhang, Qun; Van Keuren, Edward

    2008-09-15

    Two right-angle bends for nanoscale slot waveguides with high bending efficiency based on a corner mirror and different resonant cavities are presented, one with a triangular cavity and the other with a square cavity. Through two-dimensional parametric scanning of the position of the mirror and the dimension of the cavity, a maximum bending efficiency calculated using mode overlap integral (MOI) of 94.3% is achieved for the bend with the triangular cavity and 93.1% is achieved for the bend with the square cavity. Although they both have similar bending performance, the position of the mirror is different between the two cases. PMID:18794968

  1. Remarkable anti-trichomonas vaginalis activity of plants traditionally used by the Mbyá-Guarani indigenous group in Brazil.

    PubMed

    Brandelli, Clara Lia Costa; Vieira, Patrícia de Brum; Macedo, Alexandre José; Tasca, Tiana

    2013-01-01

    Trichomonas vaginalis, a flagellate protozoan, is the causative agent of trichomonosis, the most common nonviral sexually transmitted disease worldwide. Taking into account the increased prevalence of metronidazole-resistant isolates, alternative drugs are essential for the successful treatment. Natural products are the source of most new drugs, and popular wisdom about the use of medicinal plants is a powerful tool in this search. In this study, the activity of 10 medicinal plants extensively used in daily life by Mbyá-Guarani indigenous group was evaluated against seven different T. vaginalis isolates. Among the aqueous extracts tested, Verbena sp. (Guachu ka'a in Mbyá-Guarani language) and Campomanesia xanthocarpa (Guavira in Mbyá-Guarani language) showed the highest activity against T. vaginalis with MIC value of 4.0 mg/mL reaching 100% of efficacy against the parasite. The kinetic growth assays showed that the extracts promoted complete growth abolishment after 4 h of incubation. In addition, the extracts tested did not promote a significant hemolytic activity against human erythrocytes. Our results show for the first time the potential activity of Verbena sp. and C. xanthocarpa against T. vaginalis. In addition, this study demonstrates that indigenous knowledge is an important source of new prototype antiprotozoal agents. PMID:23865068

  2. Remarkable Anti-Trichomonas vaginalis Activity of Plants Traditionally Used by the Mbyá-Guarani Indigenous Group in Brazil

    PubMed Central

    Brandelli, Clara Lia Costa; Vieira, Patrícia de Brum; Macedo, Alexandre José; Tasca, Tiana

    2013-01-01

    Trichomonas vaginalis, a flagellate protozoan, is the causative agent of trichomonosis, the most common nonviral sexually transmitted disease worldwide. Taking into account the increased prevalence of metronidazole-resistant isolates, alternative drugs are essential for the successful treatment. Natural products are the source of most new drugs, and popular wisdom about the use of medicinal plants is a powerful tool in this search. In this study, the activity of 10 medicinal plants extensively used in daily life by Mbyá-Guarani indigenous group was evaluated against seven different T. vaginalis isolates. Among the aqueous extracts tested, Verbena sp. (Guachu ka'a in Mbyá-Guarani language) and Campomanesia xanthocarpa (Guavira in Mbyá-Guarani language) showed the highest activity against T. vaginalis with MIC value of 4.0 mg/mL reaching 100% of efficacy against the parasite. The kinetic growth assays showed that the extracts promoted complete growth abolishment after 4 h of incubation. In addition, the extracts tested did not promote a significant hemolytic activity against human erythrocytes. Our results show for the first time the potential activity of Verbena sp. and C. xanthocarpa against T. vaginalis. In addition, this study demonstrates that indigenous knowledge is an important source of new prototype antiprotozoal agents. PMID:23865068

  3. Measuring graphene's bending stiffness

    NASA Astrophysics Data System (ADS)

    Blees, Melina; Barnard, Arthur; Roberts, Samantha; Kevek, Joshua W.; Ruyack, Alexander; Wardini, Jenna; Ong, Peijie; Zaretski, Aliaksandr; Wang, Siping; McEuen, Paul L.

    2013-03-01

    Graphene's unusual combination of in-plane strength and out-of-plane flexibility makes it promising for mechanical applications. A key value is the bending stiffness, which microscopic theories and measurements of phonon modes in graphite put at κ0 = 1.2 eV.1 However, theories of the effects of thermal fluctuations in 2D membranes predict that the bending stiffness at longer length scales could be orders of magnitude higher.2,3 This macroscopic value has not been measured. Here we present the first direct measurement of monolayer graphene's bending stiffness, made by mechanically lifting graphene off a surface in a liquid and observing both motion induced by thermal fluctuations and the deflection caused by gravity's effect on added weights. These experiments reveal a value κeff = 12 keV at room temperature -- four orders of magnitude higher than κ0. These results closely match theoretical predictions of the effects of thermally-induced fluctuations which effectively thicken the membrane, dramatically increasing its bending stiffness at macroscopic length scales.

  4. Evaluating the Psychometric Properties of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS) among Italian Nurses: How Many Factors Must a Researcher Consider?

    PubMed Central

    Loera, Barbara; Converso, Daniela; Viotti, Sara

    2014-01-01

    Background The Maslach Burnout Inventory (MBI) is the mainstream measure for burnout. However, its psychometric properties have been questioned, and alternative measurement models of the inventory have been suggested. Aims Different models for the number of items and factors of the MBI-HSS, the version of the Inventory for the Human Service sector, were tested in order to identify the most appropriate model for measuring burnout in Italy. Methods The study dataset consisted of a sample of 925 nurses. Ten alternative models of burnout were compared using confirmatory factor analysis. The psychometric properties of items and reliability of the MBI-HSS subscales were evaluated. Results Item malfunctioning may confound the MBI-HSS factor structure. The analysis confirmed the factorial structure of the MBI-HSS with a three-dimensional, 20-item assessment. Conclusions The factorial structure underlying the MBI-HSS follows Maslach’s definition when items are reduced from the original 22 to a 20-item set. Alternative models, either with fewer items or with an increased number of latent dimensions in the burnout structure, do not yield better results to justify redefining the item set or theoretically revising the syndrome construct. PMID:25501716

  5. Intestinal parasitism and socio-environmental factors among Mbyá-Guarani Indians, Porto Alegre, Rio Grande do Sul, Brazil.

    PubMed

    Brandelli, Clara Lia Costa; de Carli, Geraldo Attilio; Macedo, Alexandre José; Tasca, Tiana

    2012-01-01

    Disturbing data reveal the prevalence of intestinal parasites and their relationship with socio-environmental factors among Mbyá-Guarani Indians. The prevalence was determined by spontaneous sedimentation in water, centrifugation-floatation, and Kato-Katz. A socioeconomic questionnaire was submitted to each family. The overall prevalence of intestinal parasites was 88.7%, and 45.5% were polyparasitized. There was 90.5% prevalence of enteric parasites in children (1-12- year-old), and 85% among 13-65-year-old individuals, indicating that both age groups are extensively parasitized. The parasite load was low to moderate for geohelminths and 75% of the families did not have latrine, thus the practice of defecation occurred outdoors. These findings suggest that the multiple intestinal parasitism in the Mbyá-Guarani community is high to the point of being the rule, and that it relates essentially to the traditional lifestyle and health habits. It is urgently necessary to implement the association of anti-parasitic treatment with sanitation improvement. This should be done simultaneously with health education activities for this population. PMID:22634881

  6. Phase trombones with bending

    SciTech Connect

    Courant, E.D.; Garren, A.

    1985-10-01

    The phase shifting trombones considered up to now for SSC application consisted of sets of evenly spaced quadrupoles separated by drift spaces. One such trombone was placed between a dispersion suppressor and a crossing insertion, so that the trombone had zero dispersion. With such trombones, it is possible to change {beta}{sup *} at constant tune, or to change the tunes by several units without altering the cell phase advances in the arcs. An objection to the above type of phase trombone is that it adds to the circumference, since no bending is included. This objection may or may not be valid depending on the potential usefulness of the drift spaces in them. In this note the authors show an alternative trombone design in which dipoles are included between the quadrupoles as in the normal arc cells. Since these trombones have dispersion, they are placed at the ends of the arcs, to be followed in turn by the dispersion suppressors and crossing insertions.

  7. Condition and residual life assessment of seamless steam pipe bends

    SciTech Connect

    Dufour, L.B.

    1995-12-01

    The majority of steam pipe bends in Dutch power plants are seamless. Reliable assessment of the condition of seamless bends after {approximately}100,000 hours of operation and beyond is a very complex and sometime frustrating procedure. Complex because external pipe forces can influence the damage and/or strain distribution in the bend. Besides, metallurgical, wall thickness and ovality variations are present anyhow, making the damage distribution in fact unknown. In accordance with a Dutch authority rule, a seamless bend is tested using a magnetic particles and investigated metallurgically with the aid of five surface replicas. Sometime more replicas are investigated and wall thickness and diameter measurements are performed as well. Occasionally, strain measurements are executed by applying capacitive strain gauges and the speckle correlation technique. In rare cases samples are taken from the first bend near the boiler outlet in order to perform isostress creep tests, allowing the determination of the condition and the residual life of other bends in the pipe systems. Based on years of experience the authors have learned that there is no single method or technique capable of assessing the condition and residual life of seamless steam pipe bends. Some experiences will be highlighted, together with recent developments in the field of quantified creep (void) damage--in order to determine inspection intervals--and the field of the speckle correlation technique.

  8. Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Ping; Wen, Yu-Mei; Zhu, Yong

    2013-07-01

    As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation, the ME effect is significantly enhanced in the vicinity of resonance frequency. The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied, and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the ΔE effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses. The experimental results show that with Hdc increasing from 0 Oe (1 Oe=79.5775 A/m) to 700 Oe, the bending resonance frequency can be shifted in a range of 32.68 kHz <= fr <= 33.96 kHz. In addition, with the thickness of the FeCuNbSiB layer increasing from 0 μm to 90 μm, the bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz. This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite, which plays a guiding role in the ME composite design for real applications.

  9. Hysteresis of the resonance frequency of magnetostrictive bending cantilevers

    NASA Astrophysics Data System (ADS)

    Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard

    2015-05-01

    Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ΔE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.

  10. ACHRO: A program to help design achromatic bends

    SciTech Connect

    Rusthoi, D.

    1993-01-01

    ACHRO is a very simple 2000-line. FORTRAN code that provides help for the designer of the achromatic bend. Given a beam momentum, the program calculates the required drift lengths and dipole parameters which it will apply to any one of several different types of achromats. The types of achromats that the code helps to design include the Enge dual-270,'' the Brown 2-dipole, the Leboutet 3-dipole, and the Enge 4-dipole, as well as the periodic systems which can be designed to any order in symmetric, nonsymmetric and stair-step varieties. Given the dimensions into which a bend must fit, ACHRO will calculate the geometrical parameters in an X-Y plane for a single or multiple achromat, and for achromatic S-bend'' configurations where possible. ACHRO makes it very easy to optimize a bend with respect to drift lengths and magnet parameters by allowing the user to change parameter values and see the resulting calculation. Used in conjunction with a beam-transport code, ACHRO makes it possible for a designer to consider various types of achromatic bends in the same beamline layout in order to compare important bend characteristics such as dispersion, Isochronicity, sensitivity, geometric and chromatic aberrations, aperture requirements, space for diagnostics, etc., all of which are largely a function of the geometry and the type of achromat selected.

  11. ACHRO: A program to help design achromatic bends

    SciTech Connect

    Rusthoi, D.

    1993-03-01

    ACHRO is a very simple 2000-line. FORTRAN code that provides help for the designer of the achromatic bend. Given a beam momentum, the program calculates the required drift lengths and dipole parameters which it will apply to any one of several different types of achromats. The types of achromats that the code helps to design include the Enge dual-270,`` the Brown 2-dipole, the Leboutet 3-dipole, and the Enge 4-dipole, as well as the periodic systems which can be designed to any order in symmetric, nonsymmetric and stair-step varieties. Given the dimensions into which a bend must fit, ACHRO will calculate the geometrical parameters in an X-Y plane for a single or multiple achromat, and for achromatic ``S-bend`` configurations where possible. ACHRO makes it very easy to optimize a bend with respect to drift lengths and magnet parameters by allowing the user to change parameter values and see the resulting calculation. Used in conjunction with a beam-transport code, ACHRO makes it possible for a designer to consider various types of achromatic bends in the same beamline layout in order to compare important bend characteristics such as dispersion, Isochronicity, sensitivity, geometric and chromatic aberrations, aperture requirements, space for diagnostics, etc., all of which are largely a function of the geometry and the type of achromat selected.

  12. Bending fracture in carbon nanotubes.

    PubMed

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. PMID:21730690

  13. Bending rules for animal propulsion.

    PubMed

    Lucas, Kelsey N; Johnson, Nathan; Beaulieu, Wesley T; Cathcart, Eric; Tirrell, Gregory; Colin, Sean P; Gemmell, Brad J; Dabiri, John O; Costello, John H

    2014-01-01

    Animal propulsors such as wings and fins bend during motion and these bending patterns are believed to contribute to the high efficiency of animal movements compared with those of man-made designs. However, efforts to implement flexible designs have been met with contradictory performance results. Consequently, there is no clear understanding of the role played by propulsor flexibility or, more fundamentally, how flexible propulsors should be designed for optimal performance. Here we demonstrate that during steady-state motion by a wide range of animals, from fruit flies to humpback whales, operating in either air or water, natural propulsors bend in similar ways within a highly predictable range of characteristic motions. By providing empirical design criteria derived from natural propulsors that have convergently arrived at a limited design space, these results provide a new framework from which to understand and design flexible propulsors. PMID:24548870

  14. Method for uniformly bending conduits

    DOEpatents

    Dekanich, S.J.

    1984-04-27

    The present invention is directed to a method for bending metal tubing through various radii while maintaining uniform cross section of the tubing. The present invention is practical by filling the tubing to a sufficient level with water, freezing the water to ice and bending the ice-filled tubing in a cooled die to the desired radius. The use of the ice as a filler material provides uniform cross-sectional bends of the tubing and upon removal of the ice provides an uncontaminated interior of the tubing which will enable it to be used in its intended application without encountering residual contaminants in the tubing due to the presence of the filler material.

  15. Superconducting Bi2Te: Pressure-induced universality in the (Bi2)m(Bi2Te3)n series

    DOE PAGESBeta

    Stillwell, Ryan L.; Jeffries, Jason R.; Jenei, Zsolt; Weir, Samuel T.; Vohra, Yogesh K.

    2016-03-09

    Using high-pressure magnetotransport techniques we have discovered superconductivity in Bi2Te, a member of the infinitely adaptive (Bi2)m(Bi2Te3)n series, whose end members, Bi and Bi2Te3, can be tuned to display topological surface states or superconductivity. Bi2Te has a maximum Tc = 8.6 K at P = 14.5 GPa and goes through multiple high pressure phase transitions, ultimately collapsing into a bcc structure that suggests a universal behavior across the series. High-pressure magnetoresistance and Hall measurements suggest a semi-metal to metal transition near 5.4 GPa, which accompanies the hexagonal to intermediate phase transition seen via x-ray diffraction measurements. In addition, the linearitymore » of Hc2 (T) exceeds the Werthamer-Helfand-Hohenberg limit, even in the extreme spin-orbit scattering limit, yet is consistent with other strong spin-orbit materials. Furthermore, considering these results in combination with similar reports on strong spin-orbit scattering materials seen in the literature, we suggest the need for a new theory that can address the unconventional nature of their superconducting states.« less

  16. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  17. Characterization of bending EAP beams

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart

    2004-01-01

    Electroactive polymers are attractive actuation materials because of their large deformation, flexibility, and lightweight. A CCD camera system was constructed to record the curved shapes of bending during the activation of EAP films and image-processing software was developed to digitize the bending curves. A computer program was developed to solve the invese problem of cantilever EAP beams with tip position limiter. using the developed program and acquired curves without tip position limiter as well as the corresponding tip force, the EAP material properties of voltage-strain sensitivity and Young's modulus were determined.

  18. The bifactor model of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS)--an alternative measurement model of burnout.

    PubMed

    Mészáros, V; Adám, Sz; Szabó, M; Szigeti, R; Urbán, R

    2014-02-01

    The purpose of the present study was to examine the construct validity of the Hungarian language version of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS). A sample of 653 healthcare professionals (420 physicians and 233 nurses and nursing assistants) completed the MBI-HSS. A series of confirmatory factor analyses showed that a hierarchical bifactor model including a global burnout factor and three specific factors of emotional exhaustion, depersonalization and reduced personal accomplishment had the closest fit to the data, compared with an alternative second-order three-factor hierarchical model as well as to non-hierarchical one-factor, two-factor, three-factor, four-factor and five-factor models. However, only the global burnout factor and the specific personal accomplishment factor explained a considerable unique proportion of variance in observed scores. Our study confirms the validity of the MBI-HSS and suggests an alternative structural model, which may contribute to further understanding of the burnout construct. PMID:23349135

  19. The statistical difference between bending arcs and regular polar arcs

    NASA Astrophysics Data System (ADS)

    Kullen, A.; Fear, R. C.; Milan, S. E.; Carter, J. A.; Karlsson, T.

    2015-12-01

    In this work, the Polar UVI data set by Kullen et al. (2002) of 74 polar arcs is reinvestigated, focusing on bending arcs. Bending arcs are typically faint and form (depending on interplanetary magnetic field (IMF) By direction) on the dawnside or duskside oval with the tip of the arc splitting off the dayside oval. The tip subsequently moves into the polar cap in the antisunward direction, while the arc's nightside end remains attached to the oval, eventually becoming hook-shaped. Our investigation shows that bending arcs appear on the opposite oval side from and farther sunward than most regular polar arcs. They form during By-dominated IMF conditions: typically, the IMF clock angle increases from 60 to 90° about 20 min before the arc forms. Antisunward plasma flows from the oval into the polar cap just poleward of bending arcs are seen in Super Dual Auroral Radar Network data, indicating dayside reconnection. For regular polar arcs, recently reported characteristics are confirmed in contrast to bending arcs. This includes plasma flows along the nightside oval that originate close to the initial arc location and a significant delay in the correlation between IMF By and initial arc location. In our data set, the highest correlations are found with IMF By appearing at least 1-2 h before arc formation. In summary, bending arcs are distinctly different from regular arcs and cannot be explained by existing polar arc models. Instead, these results are consistent with the formation mechanism described in Carter et al. (2015), suggesting that bending arcs are caused by dayside reconnection.

  20. Bending behavior of lapped plastic ehv cables

    SciTech Connect

    Morgan, G H; Muller, A C

    1980-01-01

    One of the factors delaying the development of lapped polymeric cables has been their reputed poor bending characteristics. Complementary programs were begun at BNL several years ago to mathematically model the bending of synthetic tape cables and to develop novel plastic tapes designed to have moduli more favorable to bending. A series of bend tests was recently completed to evaluate the bending performance of several tapes developed for use in experimental superconducting cables. The program is discussed and the results of the bend tests are summarized.

  1. Hormonal regulation of gravitropic bending

    NASA Astrophysics Data System (ADS)

    Hu, X.; Cui, D.; Xu, X.; Hu, L.; Cai, W.

    Gravitropic bending is an important subject in the research of plant Recent data support the basics of the Cholodny-Went hypothesis indicating that differential growth in gravitropism is due to redistribution of auxin to the lower sides of gravistimulated roots but little is known regarding the molecular details of such effects So we carried a series of work surround the signals induced by auxin end center We found the endogenous signaling molecules nitric oxide NO and cGMP mediate responses to gravistimulation in primary roots of soybean Glycine max Horizontal orientation of soybean roots caused the accumulation of both NO and cGMP in the primary root tip Fluorescence confocal microcopy revealed that the accumulation of NO was asymmetric with NO concentrating in the lower side of the root Auxin induced NO accumulation in root protoplasts and asymmetric NO accumulation in root tips Gravistimulation NO and auxin also induced the accumulation of cGMP a response inhibited by removal of NO or by inhibitors of guanylyl cyclase compounds that also reduced gravitropic bending Asymmetric NO accumulation and gravitropic bending were both inhibited by an auxin transport inhibitor and the inhibition of bending was overcome by treatment with NO or 8-bromo-cGMP a cell-permeable analog of cGMP These data indicate that auxin-induced NO and cGMP mediate gravitropic curvature in soybean roots From Hu et al Plant Physiol 2005 137 663-670 The asymmetric distribution of auxin plays a fundamental role in plant gravitropic bending

  2. Membrane Bending by Protein Crowding

    NASA Astrophysics Data System (ADS)

    Stachowiak, Jeanne

    2014-03-01

    From endosomes and synaptic vesicles to the cristae of the mitochondria and the annulus of the nuclear pore, highly curved membranes are fundamental to the structure and physiology of living cells. The established view is that specific families of proteins are able to bend membranes by binding to them. For example, inherently curved proteins are thought to impose their structure on the membrane surface, while membrane-binding proteins with hydrophobic motifs are thought to insert into the membrane like wedges, driving curvature. However, computational models have recently revealed that these mechanisms would require specialized membrane-bending proteins to occupy nearly 100% of a curved membrane surface, an improbable physiological situation given the immense density and diversity of membrane-bound proteins, and the low expression levels of these specialized proteins within curved regions of the membrane. How then does curvature arise within the complex and crowded environment of cellular membranes? Our recent work using proteins involved in clathrin-mediated endocytosis, as well as engineered protein-lipid interactions, has suggested a new hypothesis - that lateral pressure generated by collisions between membrane-bound proteins can drive membrane bending. Specifically, by correlating membrane bending with quantitative optical measurements of protein density on synthetic membrane surfaces and simple physical models of collisions among membrane-bound proteins, we have demonstrated that protein-protein steric interactions can drive membrane curvature. These findings suggest that a simple imbalance in the concentration of membrane-bound proteins across a membrane surface can drive a membrane to bend, providing an efficient mechanism by which essentially any protein can contribute to shaping membranes.

  3. Bend ductility of tungsten heavy alloys

    SciTech Connect

    Gurwell, W.E.; Garnich, M.R.; Dudder, G.B.; Lavender, C.A.

    1992-11-01

    A bend ductility test is used to indicate the formability of tungsten heavy alloys sheet. The primary test bends a notchless Charpy impact specimen to a bend angle of approximately 100C. This can be augmented by a bend-completion test. Finite element modeling as well as strain-gaged bend specimens elucidate the strain distribution in the specimen as a function of material thickness and bend angle. The bend ductilities of 70%W, 807.W and 90%W alloys are characterized. As expected, decreasing thickness or tungsten content enhances bend ductility. Oxidation is not detrimental; therefore, controlled atmosphere is not required for cooling. The potentially detrimental effects of mechanical working (e.g., rolling, roller-leveling, grit blasting, and peening) and machining (e.g., cutting and sanding) are illustrated.

  4. Improved Method Of Bending Concentric Pipes

    NASA Technical Reports Server (NTRS)

    Schroeder, James E.

    1995-01-01

    Proposed method for bending two concentric pipes simultaneously while maintaining void between them replaces present tedious, messy, and labor-intensive method. Array of rubber tubes inserted in gap between concentric pipes. Tubes then inflated with relatively incompressible liquid to fill gap. Enables bending to be done faster and more cleanly, and amenable to automation of significant portion of bending process on computer numerically controlled (CNC) tube-bending machinery.

  5. Bending Stiffness of Multiwall Sandwich

    NASA Technical Reports Server (NTRS)

    Blosser, M. L.

    1983-01-01

    An analytical and experimental study was carried out to understand the extensional and flexural behavior of multiwall sandwich, a metallic insulation composed of alternate layers of flat and dimpled foil. The multiwall sandwich was structurally analyzed by using several simplifying assumptions combined with a finite element analysis. The simplifying assumptions made in this analysis were evaluated by bending and tensile tests. Test results validate the assumption that flat sheets in compression do not significantly contribute to the flexural stiffness of multiwall sandwich for the multiwall geometry tested. However, calculations show that thicker flat sheets may contribute significantly to bending stiffness and cannot be ignored. Results of this analytical approach compare well with test data; both show that the extensional stiffness of the dimpled sheet in he 0 deg direction is about 30 percent of that for a flat sheet, and that in the 45 deg direction, it is about 10 percent. The analytical and experimental multiwall bending stiffness showed good agreement for the particular geometry tested.

  6. MBiO{sub 2}Cl (M=Sr, Ba) as novel photocatalysts: Synthesis, optical property and photocatalytic activity

    SciTech Connect

    Huang, Hongwei Wang, Shuobo; Zhang, Yihe Han, Xu

    2015-02-15

    Novel quaternary photocatalysts MBiO{sub 2}Cl (M=Sr, Ba) have been successfully developed for efficient photodecomposition of RhB. Their photocatalytic mechanism was also investigated. - Highlights: • Two Bi-based compounds SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were explored as photocatalysts. • They were successfully synthesized by a solid-state reaction. • RhB can be effectively photodecomposed by SrBiO{sub 2}Cl and BaBiO{sub 2}Cl under UV light. • ·OH radicals serving as active species play important roles in degradation process. - Abstract: Two Bi-based compounds SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were successfully synthesized by a solid-state reaction and investigated as new photocatalysts for the first time. Their microstructures and optical properties were characterized by XRD, SEM and DRS. The band gaps of SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were separately determined to be 3.52 and 3.71 eV, and their E{sub CB} and E{sub VB} were also estimated. The photocatalytic activities of the as-prepared samples were evaluated by photodecomposition of rhodamine B (RhB) in aqueous solution. The results revealed that both SrBiO{sub 2}Cl and BaBiO{sub 2}Cl can be used as effective photocatalysts under UV irradiation, and SrBiO{sub 2}Cl exhibits a higher photocatalytic activity than BaBiO{sub 2}Cl, which was also verified by the PL spectra. Terephthalic acid photoluminescence probing technique (TA-PL) demonstrated that ·OH radicals serving as active species play an important role in photooxidative degradation of RhB over SrBiO{sub 2}Cl and BaBiO{sub 2}Cl. Moreover, a larger amount of ·OH radicals generation was observed over SrBiO{sub 2}Cl, which is in agreement with its higher photocatalytic activity.

  7. Where the Granular Flows Bend

    NASA Astrophysics Data System (ADS)

    Khomenko, E.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.; Gandorfer, A.; Bonet, J. A.; Domingo, V.; Schmidt, W.; Barthol, P.; Knölker, M.

    2010-11-01

    Based on IMaX/SUNRISE data, we report on a previously undetected phenomenon in solar granulation. We show that in a very narrow region separating granules and intergranular lanes, the spectral line width of the Fe I 5250.2 Å line becomes extremely small. We offer an explanation of this observation with the help of magneto-convection simulations. These regions with extremely small line widths correspond to the places where the granular flows bend from upflow in granules to downflow in intergranular lanes. We show that the resolution and image stability achieved by IMaX/SUNRISE are important requisites to detect this interesting phenomenon.

  8. Bending of electromagnetic waves in all-dielectric particle array waveguides

    SciTech Connect

    Savelev, Roman S.; Filonov, Dmitry S.; Kapitanova, Polina V.; Krasnok, Alexander E.; Belov, Pavel A.; Miroshnichenko, Andrey E.; Kivshar, Yuri S.

    2014-11-03

    We propose and demonstrate experimentally an alternative approach for realizing subwavelength photonic structures, exploiting the waveguiding properties of chains of high-index dielectric disks with both electric and magnetic dipole resonances. We reveal that the electromagnetic energy can be efficiently guided through sharp corners by means of the mode polarization conversion at waveguide bends. We confirm experimentally the guidance through a 90° bend in the microwave frequency range.

  9. Medicinal Plants Used by a Mbyá-Guarani Tribe Against Infections: Activity on KPC-Producing Isolates and Biofilm-Forming Bacteria.

    PubMed

    Brandelli, Clara Lia Costa; Ribeiro, Vanessa Bley; Zimmer, Karine Rigon; Barth, Afonso Luís; Tasca, Tiana; Macedo, Alexandre José

    2015-11-01

    The traditional use of medicinal plants for treatment of infectious diseases by an indigenous Mbyá-Guarani tribe from South Brazil was assessed by evaluating the antibiotic and antibiofilm activities against relevant bacterial pathogens. Aqueous extracts from 10 medicinal plants were prepared according to indigenous Mbyá-Guarani traditional uses. To evaluate antibiotic (OD600) and antibiofilm (crystal violet method) activities, Pseudomonas aeruginosa ATCC 27853, Staphylococcus epidermidis ATCC 35984 and seven multi-drug resistant Klebsiella pneumoniae carbapenemase (KPC)-producing bacterial clinical isolates were challenged with the extracts. Furthermore, the susceptibility profile of KPC-producing bacteria and the ability of these isolates to form biofilm were evaluated. The plants Campomanesia xanthocarpa, Maytenus ilicifolia, Bidens pilosa and Verbena sp. showed the best activity against bacterial growth and biofilm formation. The majority of KPC-producing isolates, which showed strong ability to form biofilm and a multidrug resistance profile, was inhibited by more than 50% by some extracts. The Enterobacter cloacae (KPC 05) clinical isolate was the only one resistant to all extracts. This study confirms the importance of indigenous traditional medicinal knowledge and describes for the first time the ability of these plants to inhibit biofilm formation and/or bacterial growth of multi-drug resistant KPC-producing isolates. PMID:26749812

  10. Dynamic hysteretic sensing model of bending-mode Galfenol transducer

    SciTech Connect

    Cao, Shuying Zheng, Jiaju; Sang, Jie; Zhang, Pengfei; Wang, Bowen; Huang, Wenmei

    2015-05-07

    A dynamic hysteretic sensing model has been developed to predict the dynamic responses of the magnetic induction, the stress, and the output voltage for a bending-mode Galfenol unimorph transducer subjected simultaneously to acceleration and bias magnetic field. This model is obtained by coupling the hysteretic Armstrong model and the structural dynamic model of the Galfenol unimorph beam. The structural dynamic model of the beam is founded based on the Euler-Bernouli beam theory, the nonlinear constitutive equations, and the Faraday law of electromagnetic induction. Comparisons between the calculated and measured results show the model can describe dynamic nonlinear voltage characteristics of the device, and can predict hysteretic behaviors between the magnetic induction and the stress. Moreover, the model can effectively analyze the effects of the bias magnetic field, the acceleration amplitude, and frequency on the root mean square voltage of the device.

  11. Kerr microscopy studies of the effects of bending stress on galfenola)

    NASA Astrophysics Data System (ADS)

    Raghunath, Ganesh; Marana, Michael; Na, Suok-Min; Flatau, Alison

    2014-05-01

    This work deals with using a magneto-optic Kerr effect (MOKE) microscope to optically analyze the evolution of magnetic domains in a rolled and Goss textured galfenol (Fe81Ga19 + 1.0% NbC) sample when subjected to a bending stress. The initial magnetization state of the cantilevered sample was fixed along its length by a 0.3 T permanent magnet. The magnetic state was monitored with the MOKE microscope as a tip load was applied to bend the sample. The magnetic state of galfenol depends on its magneto-elastic properties. A finite element model that incorporates an energy based formulation of magnetostriction [W. D. Armstrong, J. Magn. Magn. Mater. 263(1-2), 208-218 (2003)] was used to investigate the stresses in the sample and the corresponding change in the magnetic induction as bending occurred. A qualitative comparison with the domain pictures is presented, and the experimental micromagnetic behavior results are shown to correlate well to the macro scale bending stress and magnetization results obtained in the FEM simulations.

  12. Band Bending Inversion in Bi2Se3 Nanostructures.

    PubMed

    Veyrat, Louis; Iacovella, Fabrice; Dufouleur, Joseph; Nowka, Christian; Funke, Hannes; Yang, Ming; Escoffier, Walter; Goiran, Michel; Eichler, Barbara; Schmidt, Oliver G; Büchner, Bernd; Hampel, Silke; Giraud, Romain

    2015-11-11

    Shubnikov-de Haas oscillations were studied under high magnetic field in Bi2Se3 nanostructures grown by chemical vapor transport, for different bulk carrier densities ranging from 3 × 10(19) cm(-3) to 6 × 10(17) cm(-3). The contribution of topological surface states to electrical transport can be identified and separated from bulk carriers and massive two-dimensional electron gas. Band bending is investigated, and a crossover from upward to downward band bending is found at low bulk density as a result of a competition between bulk and interface doping. These results highlight the need to control electrical doping both in the bulk and at interfaces in order to study only topological surface states. PMID:26479681

  13. Peeling, sliding, pulling and bending

    NASA Astrophysics Data System (ADS)

    Lister, John; Peng, Gunnar

    2015-11-01

    The peeling of an elastic sheet away from thin layer of viscous fluid is a simply-stated and generic problem, that involves complex interactions between the flow and elastic deformation on a range of length scales. Consider an analogue of capillary spreading, where a blister of injected viscous fluid spreads due to tension in the overlying elastic sheet. Here the tension is coupled to the deformation of the sheet, and thus varies in time and space. A key question is whether or not viscous shear stresses ahead of the blister are sufficient to prevent the sheet sliding inwards and relieving the tension. Our asymptotic analysis reveals a dichotomy between fast and slow spreading, and between two-dimensional and axisymmetric spreading. In combination with bending stresses and gravity, which may dominate parts of the flow but not others, there is a plethora of dynamical regimes.

  14. 46 CFR 56.80-5 - Bending.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....1 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). This shall not prohibit the use of..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Bending and Forming § 56.80-5 Bending. Pipe may be bent by any hot or cold method and to any radius which will...

  15. Direct Spectroscopic Observation of Large Quenching of First Order Orbital Angular Momentum with Bending in Monomeric, Two-Coordinate Fe(II) Primary Amido Complexes and the Profound Magnetic Effects of the Absence of Jahn- and Renner-Teller Distortions in Rigorously Linear Coordination

    PubMed Central

    Merrill, W. Alexander; Stich, Troy A.; Brynda, Marcin; Yeagle, Gregory J.; Fettinger, James C.; De Hont, Raymond; Reiff, William M.; Schulz, Charles E.; Britt, R. David; Power, Philip P.

    2009-01-01

    The monomeric iron(II) amido derivatives Fe{N(H)Ar*}2 (1), Ar* = C6H3-2,6-(C6H2-2,4,6-Pri3)2, and Fe{N(H)Ar#}2 (2), Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, were synthesized and studied in order to determine the effects of geometric changes on their unusual magnetic properties. The compounds, which are the first stable homoleptic primary amides of iron(II), were obtained by the transamination of Fe{N(SiMe3)2}2, with HN(SiMe3)2 elimination, by the primary amines H2NAr* or H2NAr#. X-ray crystallography shows that they have either strictly linear (1) or bent (2, N–Fe–N = 140.9(2)°) iron coordination. Variable temperature magnetization and applied magnetic field Mössbauer spectroscopy studies reveal a very large dependence of the magnetic properties on the metal coordination geometry. At ambient temperature, the linear 1 displayed an effective magnetic moment in the range 7.0 to 7.50 μB, consistent with essentially free ion magnetism. There is a very high internal orbital field component, HL ≈ 170 T which is only exceeded by a HL ≈ 203 T of Fe{C(SiMe3)3}2. In contrast, the strongly bent 2 displays a significantly lower μeff value in the range 5.25 to 5.80 μB at ambient temperature and a much lower orbital field HL value of 116 T. The data for the two amido complexes demonstrate a very large quenching of the orbital magnetic moment upon bending the linear geometry. In addition, a strong correlation of HL with overall formal symmetry is confirmed. ESR spectroscopy supports the existence of large orbital magnetic moments in 1 and 2, and DFT calculations provide good agreement with the physical data. PMID:19670870

  16. Effects of repetitive bending on the magnetoresistance of a flexible spin-valve

    SciTech Connect

    Kwon, J.-H.; Kwak, W.-Y.; Cho, B. K.; Choi, H. Y.; Kim, G. H.

    2015-05-07

    A positive magnetostrictive single layer (CoFe) and top-pinned spin-valve structure with positive magnetostrictive free (NiFe) and pinned (CoFe) layers were deposited on flexible polyethylene terephthalate film to investigate the changes in the magnetic properties in flexible environments, especially with a repetitive bending process. It was found that the stress, applied by repetitive bending, changes significantly the magnetic anisotropy of both layers in a single and spin-valve structure depending on the direction of applied stress. The changes in magnetic anisotropy were understood in terms of the inverse magnetostriction effect (the Villari effect) and the elastic recovery force from the flexibility of the polymer substrate. Repetitive bending with tensile stress transverse (or parallel) to the magnetic easy axis was found to enhance (or reduce) the magnetic anisotropy and, consequently, the magnetoresistance ratio of a spin-valve. The observed effects of bending stress in this study should be considered for the practical applications of electro-magnetic devices, especially magneto-striction sensor.

  17. Wire and Cable Cold Bending Test

    NASA Technical Reports Server (NTRS)

    Colozza, Anthony

    2010-01-01

    One of the factors in assessing the applicability of wire or cable on the lunar surface is its flexibility under extreme cold conditions. Existing wire specifications did not address their mechanical behavior under cold, cryogenic temperature conditions. Therefore tests were performed to provide this information. To assess this characteristic 35 different insulated wire and cable pieces were cold soaked in liquid nitrogen. The segments were then subjected to bending and the force was recorded. Any failure of the insulation or jacketing was also documented for each sample tested. The bending force tests were performed at room temperature to provide a comparison to the change in force needed to bend the samples due to the low temperature conditions. The results from the bending tests were plotted and showed how various types of insulated wire and cable responded to bending under cold conditions. These results were then used to estimate the torque needed to unroll the wire under these low temperature conditions.

  18. Bending of light in conformal Weyl gravity

    NASA Astrophysics Data System (ADS)

    Sultana, Joseph; Kazanas, Demosthenes

    2010-06-01

    We reexamine the bending of light issue associated with the metric of the static, spherically symmetric solution of Weyl gravity discovered by Mannheim and Kazanas (1989). To this end we employ the procedure used recently by Rindler and Ishak to obtain the bending angle of light by a centrally concentrated spherically symmetric matter distribution in a Schwarzschild-de Sitter background. In earlier studies the term γr in the metric led to the paradoxical result of a bending angle proportional to the photon impact parameter, when using the usual formalism appropriate to asymptotically flat space-times. However, employing the approach of light bending of Rindler and Ishak we show that the effects of this term are in fact insignificant, with the discrepancy between the two procedures attributed to the definition of the bending angle between the asymptotically flat and nonflat spaces.

  19. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel... wrinkle bend on steel pipe must comply with the following: (1) The bend must not have any sharp kinks....

  20. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel... wrinkle bend on steel pipe must comply with the following: (1) The bend must not have any sharp kinks....

  1. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel... wrinkle bend on steel pipe must comply with the following: (1) The bend must not have any sharp kinks....

  2. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel... wrinkle bend on steel pipe must comply with the following: (1) The bend must not have any sharp kinks....

  3. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel... wrinkle bend on steel pipe must comply with the following: (1) The bend must not have any sharp kinks....

  4. 49 CFR 195.212 - Bending of pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Bending of pipe. 195.212 Section 195.212... PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field bend must comply with the following: (1) A bend must not impair the serviceability of the pipe. (2)...

  5. Gravitropic bending of fruit bodies

    NASA Astrophysics Data System (ADS)

    Hock, Bertold

    Fruit bodies of basidiomycetes exhibit a unique mechanism of gravitropic bending, related to their specific architecture. The gravisensitive region of the stipe directly below the cap coincides with the bending zone. The hyphae of this region are equipped with the ability to generate positional information and translate it into differential growth. A model is introduced with the fundamental characteristics of agent-based modeling as it is applied in robotics and artificial intelligence. The hyphae are equivalent to autonomous decision-making agents on the basis of a simple set of rules. Repetitive interactions between the agents, i.e. the hyphae, permit the correct adjustment of the fruit body independent from its relative position in space. This model is based on the following structural as well as biochemical data derived from the basidiomycete Flammulina velutipes. A statolith-mediated mechanism in each individual hypha of the gravisensitive region accounts for graviperception. Cell nuclei with a density of 1.22 g cm-3 are considered the most likely candidates for gravity-induced sedimentation (statoliths). The number of nuclei in this zone is increased from 2 to up to 10 individual nuclei within each hyphal compartment. The nuclei are suspended in a web of actin filaments anchored in the plasma membrane. Any shift from the vertical position is converted into a change in the gravitational pull exerted on the plasma membrane. This leads to a functional distinction of the upper and lower flanks of each hypha. Each hypha is equipped with the ability to generate and amplify a positional signal perpendicular to the axis of the gravisensitive zone. This signal coordinates different hyphal extension of the upper and lower flank of the stipe: upper flank hyphae grow slower than lower flank hyphae. Hyphal growth requires continued turgor pressure and depends on the expansion of the vacuolar compartment. This vacuolation is conspicuously increased in lower flank

  6. Bend Properties of Sapphire Fibers at Elevated Temperatures. 1; Bend Survivability

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Sayir, Haluk

    1995-01-01

    The effect of temperature on the bend radius that a c-axis-oriented sapphire fiber can withstand was determined for fibers of various diameter. Bend stress rupture tests were performed for times of 1-100 h and temperatures of 300-1700 C. Fibers would survive the bend test undeformed, would fracture or would deform. The bend survival radius was determined to be the radius above which no fibers fractured or deformed for a given time-temperature treatment. It was found that the ability of fibers to withstand curvature decreases substantially with time and increasing temperature and that fibers of smaller diameter (46-83 micron) withstood smaller bend radii than would be expected from just a difference in fiber diameter when compared with the bend results of the fibers of large diameter (144 micron). This was probably due to different flaw populations, causing high temperature bend failure for the tested sapphire fibers of different diameters.

  7. Initial Ares I Bending Filter Design

    NASA Technical Reports Server (NTRS)

    Jang, Jiann-Woei; Bedrossian, Nazareth; Hall, Robert; Norris, H. Lee; Hall, Charles; Jackson, Mark

    2007-01-01

    The Ares-I launch vehicle represents a challenging flex-body structural environment for control system design. Software filtering of the inertial sensor output will be required to ensure control system stability and adequate performance. This paper presents a design methodology employing numerical optimization to develop the Ares-I bending filters. The filter design methodology was based on a numerical constrained optimization approach to maximize stability margins while meeting performance requirements. The resulting bending filter designs achieved stability by adding lag to the first structural frequency and hence phase stabilizing the first Ares-I flex mode. To minimize rigid body performance impacts, a priority was placed via constraints in the optimization algorithm to minimize bandwidth decrease with the addition of the bending filters. The bending filters provided here have been demonstrated to provide a stable first stage control system in both the frequency domain and the MSFC MAVERIC time domain simulation.

  8. Thermal static bending of deployable interlocked booms

    NASA Technical Reports Server (NTRS)

    Staugaitis, C. L.; Predmore, R. E.

    1973-01-01

    Metal ribbons processed with a heat-forming treatment are enabled to form tubelike structures when deployed from a roll. Deployable booms of this have been utilized for gravity-gradient stabilization on the RAE, ATS, and Nimbus D satellites. An experimental thermal-mechanics test apparatus was developed to measure the thermal static bending and twist of booms up to 3 meters long. The apparatus was calibrated by using the correlation between calculated and observed thermal bending of a seamless tube. Thermal static bending values of 16 interlocked deployable booms were observed to be within a factor of 2.5 of the values calculated from seamless-tube theory. Out-of-Sun-plane thermal bending was caused by complex heat transfer across the interlocked seam. Significant thermal static twisting was not observed.

  9. Turbulent flow analysis on bend and downstream of the bend for different curvature ratio

    NASA Astrophysics Data System (ADS)

    Chowdhury, Rana Roy; Biswas, Suranjan; Alam, Md. Mahbubul; Islam, A. K. M. Sadrul

    2016-07-01

    A CFD analysis on the bend and downstream of the bend has been carried out for turbulent flow through 90 degree bend pipe with different curvature ratios using standard k-epsilon turbulence model. Numerical results are compared with the existing experimental results, and then a detailed study has been performed to investigate the flow characteristics. For different curvature ratios, the static pressure distributions along inner, outer wall and pressure loss factor with different Reynolds number is analyzed. The obtained results show that pressure distribution and pressure loss factor are dependent for different Reynolds number and curvature ratio throughout the bend. Again, It is observed that the disturbance of the flow due to bend exists for a downstream distance of 50D from the central plane of the bend.

  10. Bending rigidity of composite resin coating clasps.

    PubMed

    Ikebe, K; Kibi, M; Ono, T; Nokubi, T

    1993-12-01

    The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps. PMID:8935086

  11. A transparent bending-insensitive pressure sensor

    NASA Astrophysics Data System (ADS)

    Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao

    2016-05-01

    Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.

  12. A transparent bending-insensitive pressure sensor.

    PubMed

    Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao

    2016-05-01

    Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions. PMID:26809055

  13. fMRI-Compatible Registration of Jaw Movements Using a Fiber-Optic Bend Sensor.

    PubMed

    Sörös, Peter; Macintosh, Bradley J; Tam, Fred; Graham, Simon J

    2010-01-01

    A functional magnetic resonance imaging (fMRI)-compatible fiber-optic bend sensor was investigated to assess whether the device could be used effectively to monitor opening and closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a bend sensor fixed to the chin of the participant is fast and easy to use and is not affected by strong electromagnetic fields. Bend sensor recordings are characterized by high validity (compared with concurrent video recordings of mouth opening) and high reliability (comparing two independent measurements). The results of this study indicate that a bend sensor is able to record the opening and closing of the jaw associated with different overt speech conditions (producing the utterances /a/, /pa/, /pataka/) and the opening of the mouth without speech production. Data post-processing such as filtering was not necessary. There are several potential applications for bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are a valuable tool to assess behavioral performance, such as response latencies, accuracies, and completion times, which is particularly important in children, seniors, or patients with various neurological or psychiatric conditions. Second, the timing information provided by bend sensor data may improve the predicted hemodynamic response that is used for fMRI analysis based on the general linear model (GLM). Third, bend sensor recordings may be included in GLM analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for part of the data variance to model fMRI artifacts due to motion outside the field of view. PMID:20463865

  14. fMRI-Compatible Registration of Jaw Movements Using a Fiber-Optic Bend Sensor

    PubMed Central

    Sörös, Peter; MacIntosh, Bradley J.; Tam, Fred; Graham, Simon J.

    2009-01-01

    A functional magnetic resonance imaging (fMRI)-compatible fiber-optic bend sensor was investigated to assess whether the device could be used effectively to monitor opening and closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a bend sensor fixed to the chin of the participant is fast and easy to use and is not affected by strong electromagnetic fields. Bend sensor recordings are characterized by high validity (compared with concurrent video recordings of mouth opening) and high reliability (comparing two independent measurements). The results of this study indicate that a bend sensor is able to record the opening and closing of the jaw associated with different overt speech conditions (producing the utterances /a/, /pa/, /pataka/) and the opening of the mouth without speech production. Data post-processing such as filtering was not necessary. There are several potential applications for bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are a valuable tool to assess behavioral performance, such as response latencies, accuracies, and completion times, which is particularly important in children, seniors, or patients with various neurological or psychiatric conditions. Second, the timing information provided by bend sensor data may improve the predicted hemodynamic response that is used for fMRI analysis based on the general linear model (GLM). Third, bend sensor recordings may be included in GLM analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for part of the data variance to model fMRI artifacts due to motion outside the field of view. PMID:20463865

  15. Form of developing bends in reactivated sperm flagella.

    PubMed

    Goldstein, S F

    1976-02-01

    1. Dark-field, multiple-exposure photographs of reactivated tritonated sea urchin sperm flagella swimming under a variety of conditions were analysed. 2. The length, radius and subtended angle of bends increased during bend development. The pattern of development was essentially the same under all conditions observed. 3. The angles of the two bends nearest the base tend to increase at the same rate, cancelling one another, so that the development of new bends causes little if any net microtubular sliding. 4. The direction of microtubular sliding within a bend is initially in the same direction as that within the preceding bend, and reverses as the bend develops. PMID:1270988

  16. A Novel Circular TE01-Mode Bend

    SciTech Connect

    Tantawi, S

    2004-04-19

    Future Linear Colliders and Accelerators require rf systems and components that are capable of handling hundreds of megawatts power levels at x-band frequencies and higher. Standard rf components that have been in use for a long time such as waveguide bends, directional couplers and hybrids, can not be used because of peak field considerations. Indeed, one has to reinvent most of these components taking into account the constraints imposed by ultra-high-power operation. Here, we present a new design for circular waveguides bends propagating the low-loss TE{sub 01} mode. The bend has smooth walls and low field levels. We present a simple synthesis process for designing such device. The general philosophy of this technique can be applied to other components as well. We describe the detailed design of the bend and compare our design with finite element simulations and experimental data. The bend has very low ohmic losses, and the TE{sub 01} mode is transmitted with virtually perfect mode purity.

  17. Sharp bends of phononic crystal surface modes

    NASA Astrophysics Data System (ADS)

    Cicek, Ahmet; Salman, Aysevil; Adem Kaya, Olgun; Ulug, Bulent

    2015-12-01

    Sharp bending of surface waves at the interface of a two-dimensional phononic crystal (PnC) of steel cylinders in air and the method of using a diagonally offset cylindrical scatterer are numerically demonstrated by finite-element method simulations. The radii of the diagonally offset scatterer and the cylinder at the PnC corner, along with the distance between them, are treated as optimization parameters in the genetic algorithm optimization of sharp bends. Surface wave transmittance of at most 5% for the unmodified sharp bend is significantly enhanced to approximately 75% as a result of optimization. A series of transmittance peaks whose maxima increase exponentially, as their widths reduce, with increasing frequency is observed for the optimized sharp bend. The transmittance peaks appear at frequencies corresponding to integer plus half-beat periods, depending on the finite surface length. The optimal parameters are such that the cylinder radius at the PnC corner is not significantly modified, whereas a diagonally offset scatterer having a diameter of almost two periods and a shortest distance of about 0.7 periods between them is required for the strongest transmittance peak. Utilization of PnC surface sharp bends as acoustic ring resonators is demonstrated.

  18. Tunable thermoelectric properties in bended graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Chang-Ning, Pan; Jun, He; Mao-Fa, Fang

    2016-07-01

    The ballistic thermoelectric properties in bended graphene nanoribbons (GNRs) are systematically investigated by using atomistic simulation of electron and phonon transport. We find that the electron resonant tunneling effect occurs in the metallic–semiconducting linked ZZ-GNRs (the bended GNRs with zigzag edge leads). The electron-wave quantum interference effect occurs in the metallic–metallic linked AA-GNRs (the bended GNRs with armchair edge leads). These different physical mechanisms lead to the large Seebeck coefficient S and high electron conductance in bended ZZ-GNRs/AA-GNRs. Combined with the reduced lattice thermal conduction, the significant enhancement of the figure of merit ZT is predicted. Moreover, we find that the ZTmax (the maximum peak of ZT) is sensitive to the structural parameters. It can be conveniently tuned by changing the interbend length of bended GNRs. The magnitude of ZT ranges from the 0.15 to 0.72. Geometry-controlled ballistic thermoelectric effect offers an effective way to design thermoelectric devices such as thermocouples based on graphene. Project supported by the National Natural Science Foundation of China (Grant No. 61401153) and the Natural Science Foundation of Hunan Province, China (Grant Nos. 2015JJ2050 and 14JJ3126).

  19. Superconducting B i2Te : Pressure-induced universality in the (Bi2) m(Bi2Te3 ) n series

    NASA Astrophysics Data System (ADS)

    Stillwell, Ryan L.; Jenei, Zsolt; Weir, Samuel T.; Vohra, Yogesh K.; Jeffries, Jason R.

    2016-03-01

    Using high-pressure magnetotransport techniques we have discovered superconductivity in B i2Te , a member of the infinitely adaptive (Bi2) m(Bi2Te3 ) n series, whose end members, Bi and B i2T e3 , can be tuned to display topological surface states or superconductivity. B i2Te has a maximum Tc=8.6 K at P =14.5 GPa and goes through multiple high-pressure phase transitions, ultimately collapsing into a bcc structure that suggests a universal behavior across the series. High-pressure magnetoresistance and Hall measurements suggest a semimetal to metal transition near 5.4 GPa, which accompanies the hexagonal to intermediate phase transition seen via x-ray diffraction measurements. In addition, the linearity of Hc 2(T ) exceeds the Werthamer-Helfand-Hohenberg limit, even in the extreme spin-orbit scattering limit, yet is consistent with other strong spin-orbit materials. Considering these results in combination with similar reports on strong spin-orbit scattering materials seen in the literature, we suggest the need for a new theory that can address the unconventional nature of their superconducting states.

  20. Mechanism of bending electrostriction in thermoplastic polyurethane

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Wong, Y. W.; Shin, F. G.

    2004-07-01

    The mechanism of bending electrostriction in polyurethane films is discussed and elucidated through a numerical calculation. The simulations are carried out on a model in which charge carriers are assumed to be electrons injected from the cathode by the Schottky effect, and the positive charges are immobile. Under a dc field, our simulation results show that the electrons go out of the anode, leaving behind a large quantity of positive charge around the anode. As a result, the electric field near the anode eventually becomes much larger than that near the cathode. The asymmetrical electric field distribution leads to an asymmetrical stress distribution through the electrostriction effect and thus to bending of the polyurethane film under the application of a dc electric field. The results can also explain the gradual change in bending direction after reversing the polarity of the electric field.

  1. Magnetic chicane for terahertz management

    DOEpatents

    Benson, Stephen; Biallas, George Herman; Douglas, David; Jordan, Kevin Carl; Neil, George R.; Michelle D. Shinn; Willams, Gwyn P.

    2010-12-28

    The introduction of a magnetic electron beam orbit chicane between the wiggler and the downstream initial bending dipole in an energy recovering Linac alleviates the effects of radiation propagated from the downstream bending dipole that tend to distort the proximate downstream mirror of the optical cavity resonator.

  2. Robotic Arm Comprising Two Bending Segments

    NASA Technical Reports Server (NTRS)

    Mehling, Joshua S.; Difler, Myron A.; Ambrose, Robert O.; Chu, Mars W.; Valvo, Michael C.

    2010-01-01

    The figure shows several aspects of an experimental robotic manipulator that includes a housing from which protrudes a tendril- or tentacle-like arm 1 cm thick and 1 m long. The arm consists of two collinear segments, each of which can be bent independently of the other, and the two segments can be bent simultaneously in different planes. The arm can be retracted to a minimum length or extended by any desired amount up to its full length. The arm can also be made to rotate about its own longitudinal axis. Some prior experimental robotic manipulators include single-segment bendable arms. Those arms are thicker and shorter than the present one. The present robotic manipulator serves as a prototype of future manipulators that, by virtue of the slenderness and multiple- bending capability of their arms, are expected to have sufficient dexterity for operation within spaces that would otherwise be inaccessible. Such manipulators could be especially well suited as means of minimally invasive inspection during construction and maintenance activities. Each of the two collinear bending arm segments is further subdivided into a series of collinear extension- and compression-type helical springs joined by threaded links. The extension springs occupy the majority of the length of the arm and engage passively in bending. The compression springs are used for actively controlled bending. Bending is effected by means of pairs of antagonistic tendons in the form of spectra gel spun polymer lines that are attached at specific threaded links and run the entire length of the arm inside the spring helix from the attachment links to motor-driven pulleys inside the housing. Two pairs of tendons, mounted in orthogonal planes that intersect along the longitudinal axis, are used to effect bending of each segment. The tendons for actuating the distal bending segment are in planes offset by an angle of 45 from those of the proximal bending segment: This configuration makes it possible to

  3. Interdisciplinary Invitations: Exploring Gee's Bend Quilts

    ERIC Educational Resources Information Center

    Mitchell, Rebecca; Whitin, Phyllis; Whitin, David

    2012-01-01

    Engaging with the quilts of Gee's Bend offers a rich opportunity for students in grades four through eight to develop appreciation for pattern, rhythm, and innovation while learning about history, entrepreneurship, and political activism. By easily accessing print, film, and Internet resources teachers can include these vibrant quilts and…

  4. Aerosol deposition in bends with turbulent flow

    SciTech Connect

    McFarland, A.R.; Gong, H.; Wente, W.B.

    1997-08-01

    The losses of aerosol particles in bends were determined numerically for a broad range of design and operational conditions. Experimental data were used to check the validity of the numerical model, where the latter employs a commercially available computational fluid dynamics code for characterizing the fluid flow field and Lagrangian particle tracking technique for characterizing aerosol losses. Physical experiments have been conducted to examine the effect of curvature ratio and distortion of the cross section of bends. If it curvature ratio ({delta} = R/a) is greater than about 4, it has little effect on deposition, which is in contrast with the recommendation given in ANSI N13.1-1969 for a minimum curvature ratio of 10. Also, experimental results show that if the tube cross section is flattened by 25% or less, the flattening also has little effect on deposition. Results of numerical tests have been used to develop a correlation of aerosol penetration through a bend as a function of Stokes number (Stk), curvature ratio ({delta}) and the bend angle ({theta}). 17 refs., 10 figs., 2 tabs.

  5. Probing the elastic limit of DNA bending

    PubMed Central

    Le, Tung T.; Kim, Harold D.

    2014-01-01

    Sharp bending of double-stranded DNA (dsDNA) plays an essential role in genome structure and function. However, the elastic limit of dsDNA bending remains controversial. Here, we measured the opening rates of small dsDNA loops with contour lengths ranging between 40 and 200 bp using single-molecule Fluorescence Resonance Energy Transfer. The relationship of loop lifetime to loop size revealed a critical transition in bending stress. Above the critical loop size, the loop lifetime changed with loop size in a manner consistent with elastic bending stress, but below it, became less sensitive to loop size, indicative of softened dsDNA. The critical loop size increased from ∼60 bp to ∼100 bp with the addition of 5 mM magnesium. We show that our result is in quantitative agreement with the kinkable worm-like chain model, and furthermore, can reproduce previously reported looping probabilities of dsDNA over the range between 50 and 200 bp. Our findings shed new light on the energetics of sharply bent dsDNA. PMID:25122748

  6. UV - BIG BEND NATIONAL PARK TX

    EPA Science Inventory

    Brewer 130 is located in Big Bend NP, measuring ultraviolet solar radiation. Irradiance and column ozone are derived from this data. Ultraviolet solar radiation is measured with a Brewer Mark IV, single-monochrometer, spectrophotometer manufactured by SCI-TEC Instruments, Inc. of...

  7. The Hungarian-Americans of South Bend.

    ERIC Educational Resources Information Center

    Scherer, Darlene; Rasmussen, Karen, Ed.

    Developed as part of an ethnic heritage studies program, this historical narrative of Hungarian Americans in South Bend, Indiana, is intended to increase cultural awareness and appreciation. The document is divided into three sections. Section I offers a brief history of Hungary and describes the background of the three emigrant groups; lower…

  8. Bending of skew plates of variable rigidity.

    NASA Technical Reports Server (NTRS)

    Willems, N.; Mahmood, S. S.

    1972-01-01

    Description of an analytical procedure for studying the bending of thin skew plates of a thickness varying in one direction, under arbitrary lateral loading. The analysis was programmed for execution on an electronic computer for various conditions and types of loading. The results obtained suggest that the proposed analytical procedure is more accurate than the finite-difference technique used in earlier investigations.

  9. Age of the Hawaiian-Emperor bend

    USGS Publications Warehouse

    Dalrymple, G.B.; Clague, D.A.

    1976-01-01

    40Ar/39Ar age data on alkalic and tholeiitic basalts from Diakakuji and Kinmei Seamounts in the vicinity of the Hawaiian-Emperor bend indicate that these volcanoes are about 41 and 39 m.y. old, respectively. Combined with previously published age data on Yuryaku and Ko??ko Seamounts, the new data indicate that the best age for the bend is 42.0 ?? 1.4 m.y. Petrochemical data indicate that the volcanic rocks recovered from bend seamounts are indistinguishable from Hawaiian volcanic rocks, strengthening the hypothesis that the Hawaiian-Emperor bend is part of the Hawaiian volcanic chain. 40Ar/39Ar total fusion ages on altered whole-rock basalt samples are consistent with feldspar ages and with 40Ar/39Ar incremental heating data and appear to reflect the crystallization ages of the samples even though conventional K-Ar ages are significantly younger. The cause of this effect is not known but it may be due to low-temperature loss of 39Ar from nonretentive montmorillonite clays that have also lost 40Ar. ?? 1976.

  10. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  11. An analytical study of double bend achromat lattice

    SciTech Connect

    Fakhri, Ali Akbar Kant, Pradeep; Singh, Gurnam; Ghodke, A. D.

    2015-03-15

    In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.

  12. Oroclinal bending of the southern sierra nevada batholith.

    PubMed

    McWilliams, M; Li, Y

    1985-10-11

    Structural, magmatic, and isotopic features of the southern Sierra Nevada batholith are deflected clockwise with respect to its central and northern parts. Directions of magnetization at three localities in the southern Sierra Nevada are progressively deflected; this is consistent with the hypothesis that the region was tectonically rotated in an orocline. No paleomagnetic deflection was observed northwest of the White Wolf-Kern Canyon fault system. Oroclinal bending ofa block bounded by the San Andreas, Garlock, and White Wolf-Kern Canyon faults may have occurred before about 16 x l0(6) years ago. The deformation may have been a response to shear at the western boundary of the North American plate caused by oblique subduction. PMID:17842695

  13. An analytical study of double bend achromat lattice

    NASA Astrophysics Data System (ADS)

    Fakhri, Ali Akbar; Kant, Pradeep; Singh, Gurnam; Ghodke, A. D.

    2015-03-01

    In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.

  14. An analytical study of double bend achromat lattice.

    PubMed

    Fakhri, Ali Akbar; Kant, Pradeep; Singh, Gurnam; Ghodke, A D

    2015-03-01

    In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented. PMID:25832220

  15. Genetic analysis of six communities of Mbyá-Guaraní inhabiting northeastern Argentina by means of nuclear and mitochondrial polymorphic markers.

    PubMed

    Sala, Andrea; Argüelles, Carina F; Marino, Miguel E; Bobillo, Cecilia; Fenocchio, Alberto; Corach, Daniel

    2010-08-01

    Autosomal STRs, Y-chromosome markers, and mitochondrial DNA sequences were investigated in six Mbyá-Guaraní villages (Fortín M'Bororé, Yryapu, Tabay, Kaaguy Poty, Jejy, and Yaboti), all of them settled within the province of Misiones, northeastern Argentina. One hundred twenty-one unrelated individuals were analyzed. The study involved typing fifteen autosomal STRs, nine Y-chromosome STRs, and four biallele loci in the nonrecombinant region of the Y chromosome, sequencing the mtDNA of hypervariable regions I and II, and detecting the 9-bp ins/del in region V of mtDNA. All autosomal STRs were in Hardy-Weinberg equilibrium. The four major native American mtDNA haplogroups were represented in the sample. Haplogroups A2 and D1 exhibited the highest frequencies (40.5% and 36.0%, respectively), and haplogroups B2 and C1 appeared to be less frequent (17.5% and 6.0%, respectively). The native American haplogroup Q1a3a was observed in a relevant proportion (88.8%). In addition, a nine-STR Y-chromosome haplo-type (DYS19*13, DYS389I*14, DYS389II*31, DYS390*24, DYS391*11, DYS392*14, DYS393*11, DYS385A*14, DYS385B*16) exhibited a frequency of more than 36%. Our results indicate that the analyzed Argentinean Guaraní individuals are genetically more closely related to Guaraní from Brazil [genetic distance (Δµ)(2) = 0.48] than to other related tribes that are geographically closer. Statistical approaches based on autosomal data do not support the hypothesis of genetic drift previously proposed; however, this apparent discrepancy might be due to the lack of sensitivity of the autosomal markers used here. PMID:21082911

  16. Mindfulness in Motion (MIM): An Onsite Mindfulness Based Intervention (MBI) for Chronically High Stress Work Environments to Increase Resiliency and Work Engagement

    PubMed Central

    Klatt, Maryanna; Steinberg, Beth; Duchemin, Anne-Marie

    2015-01-01

    A pragmatic mindfulness intervention to benefit personnel working in chronically high-stress environments, delivered onsite during the workday, is timely and valuable to employee and employer alike. Mindfulness in Motion (MIM) is a Mindfulness Based Intervention (MBI) offered as a modified, less time intensive method (compared to Mindfulness-Based Stress Reduction), delivered onsite, during work, and intends to enable busy working adults to experience the benefits of mindfulness. It teaches mindful awareness principles, rehearses mindfulness as a group, emphasizes the use of gentle yoga stretches, and utilizes relaxing music in the background of both the group sessions and individual mindfulness practice. MIM is delivered in a group format, for 1 hr/week/8 weeks. CDs and a DVD are provided to facilitate individual practice. The yoga movement is emphasized in the protocol to facilitate a quieting of the mind. The music is included for participants to associate the relaxed state experienced in the group session with their individual practice. To determine the intervention feasibility/efficacy we conducted a randomized wait-list control group in Intensive Care Units (ICUs). ICUs represent a high-stress work environment where personnel experience chronic exposure to catastrophic situations as they care for seriously injured/ill patients. Despite high levels of work-related stress, few interventions have been developed and delivered onsite for such environments. The intervention is delivered on site in the ICU, during work hours, with participants receiving time release to attend sessions. The intervention is well received with 97% retention rate. Work engagement and resiliency increase significantly in the intervention group, compared to the wait-list control group, while participant respiration rates decrease significantly pre-post in 6/8 of the weekly sessions. Participants value institutional support, relaxing music, and the instructor as pivotal to program success

  17. Mindfulness in Motion (MIM): An Onsite Mindfulness Based Intervention (MBI) for Chronically High Stress Work Environments to Increase Resiliency and Work Engagement.

    PubMed

    Klatt, Maryanna; Steinberg, Beth; Duchemin, Anne-Marie

    2015-01-01

    A pragmatic mindfulness intervention to benefit personnel working in chronically high-stress environments, delivered onsite during the workday, is timely and valuable to employee and employer alike. Mindfulness in Motion (MIM) is a Mindfulness Based Intervention (MBI) offered as a modified, less time intensive method (compared to Mindfulness-Based Stress Reduction), delivered onsite, during work, and intends to enable busy working adults to experience the benefits of mindfulness. It teaches mindful awareness principles, rehearses mindfulness as a group, emphasizes the use of gentle yoga stretches, and utilizes relaxing music in the background of both the group sessions and individual mindfulness practice. MIM is delivered in a group format, for 1 hr/week/8 weeks. CDs and a DVD are provided to facilitate individual practice. The yoga movement is emphasized in the protocol to facilitate a quieting of the mind. The music is included for participants to associate the relaxed state experienced in the group session with their individual practice. To determine the intervention feasibility/efficacy we conducted a randomized wait-list control group in Intensive Care Units (ICUs). ICUs represent a high-stress work environment where personnel experience chronic exposure to catastrophic situations as they care for seriously injured/ill patients. Despite high levels of work-related stress, few interventions have been developed and delivered onsite for such environments. The intervention is delivered on site in the ICU, during work hours, with participants receiving time release to attend sessions. The intervention is well received with 97% retention rate. Work engagement and resiliency increase significantly in the intervention group, compared to the wait-list control group, while participant respiration rates decrease significantly pre-post in 6/8 of the weekly sessions. Participants value institutional support, relaxing music, and the instructor as pivotal to program success

  18. Monitoring thermoplastic composites under cyclic bending tests

    NASA Astrophysics Data System (ADS)

    Boccardi, Simone; Meola, Carosena; Carlomagno, Giovanni Maria; Simeoli, Giorgio; Acierno, Domenico; Russo, Pietro

    2016-05-01

    This work is concerned with the use of infrared thermography to visualize temperature variations linked to thermo-elastic effects developing over the surface of a specimen undergoing deflection under bending tests. Several specimens are herein considered, which involve change of matrix and/or reinforcement. More specifically, the matrix is either a pure polypropylene, or a polypropylene added with a certain percentage of compatibilizing agent; the reinforcement is made of glass, or jute. Cyclic bending tests are carried out by the aid of an electromechanical actuator. Each specimen is viewed, during deflection, from one surface by an infrared imaging device. As main finding the different specimens display surface temperature variations which depend on the type of material in terms of both matrix and reinforcement.

  19. Combined bending-torsion fatigue reliability. III

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Chester, L. B.; Nolf, C. F., Jr.

    1975-01-01

    Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. AISI 4340 steel, grooved specimens with a stress concentration factor of 1.42 and 2.34, and Rockwell C hardness of 35/40 were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effects of the groove, and of the various combined bending-torsion loads, on the S-N and Goodman diagrams are determined. Two design applications are presented which illustrate the direct useability and value of the distributional failure governing strength and cycles-to-failure data in designing for specified levels of reliability and in predicting the reliability of given designs.

  20. Torsion and transverse bending of cantilever plates

    NASA Technical Reports Server (NTRS)

    Reissner, Eric; Stein, Manuel

    1951-01-01

    The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.

  1. Fracture of surface cracks loaded in bending

    SciTech Connect

    Chao, Y.J.; Reuter, W.G.

    1997-12-31

    Theoretical background of the constraint effect in brittle fracture of solids is reviewed. Fracture test data from D6-aC, a high strength steel, using three-point-bend (SE(B)) specimens and surface cracked plate (SC(B)) specimens under bending are presented. It is shown that the SE(B) data has an elevated fracture toughness for increasing a/W, i.e., a crack geometry with a larger T/K corresponds to a higher K{sub c} which is consistent with the theoretical prediction. The fundamental fracture properties, i.e., the critical strain and the critical distance, determined from the SE(B) test data are then applied to the interpretation and prediction of the SC(B) test data. Reasonable agreement is achieved for the crack growth initiation site and the load.

  2. Effect of confinements: Bending in Paramecium

    NASA Astrophysics Data System (ADS)

    Eddins, Aja; Yang, Sung; Spoon, Corrie; Jung, Sunghwan

    2012-02-01

    Paramecium is a unicellular eukaryote which by coordinated beating of cilia, generates metachronal waves which causes it to execute a helical trajectory. We investigate the swimming parameters of the organism in rectangular PDMS channels and try to quantify its behavior. Surprisingly a swimming Paramecium in certain width of channels executes a bend of its flexible body (and changes its direction of swimming) by generating forces using the cilia. Considering a simple model of beam constrained between two walls, we predict the bent shapes of the organism and the forces it exerts on the walls. Finally we try to explain how bending (by sensing) can occur in channels by conducting experiments in thin film of fluid and drawing analogy to swimming behavior observed in different cases.

  3. Development of Bend Sensor for Catheter Tip

    NASA Astrophysics Data System (ADS)

    Nagano, Yoshitaka; Sano, Akihito; Fujimoto, Hideo

    Recently, a minimally invasive surgery which makes the best use of the catheter has been becoming more popular. In endovascular coil embolization for a cerebral aneurysm, the observation of the catheter's painting phenomenon is very important to execute the appropriate manipulation of the delivery wire and the catheter. In this study, the internal bend sensor which consists of at least two bending enhanced plastic optical fibers was developed in order to measure the curvature of the catheter tip. Consequently, the painting could be more sensitively detected in the neighborhood of the aneurysm. In this paper, the basic characteristics of the developed sensor system are described and its usefulness is confirmed from the comparison of the insertion force of delivery wire and the curvature of catheter tip in the experiment of coil embolization.

  4. Molecular Origin of Model Membrane Bending Rigidity

    SciTech Connect

    Kurtisovski, Erol; Taulier, Nicolas; Waks, Marcel; Ober, Raymond; Urbach, Wladimir

    2007-06-22

    The behavior of the bending modulus {kappa} of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic C{sub i}E{sub j} surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of {kappa} decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of {kappa} decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to {kappa}.

  5. Molecular Origin of Model Membrane Bending Rigidity

    NASA Astrophysics Data System (ADS)

    Kurtisovski, Erol; Taulier, Nicolas; Ober, Raymond; Waks, Marcel; Urbach, Wladimir

    2007-06-01

    The behavior of the bending modulus κ of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic CiEj surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of κ decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of κ decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to κ

  6. Big Bend National Park, TX, USA, Mexico

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Sierra del Carmen of Mexico, across the Rio Grande River from Big Bend National Park, TX, (28.5N, 104.0W) is centered in this photo. The Rio Grande River bisects the scene; Mexico to the east, USA to the west. The thousand ft. Boquillas limestone cliff on the Mexican side of the river changes colors from white to pink to lavender at sunset. This severely eroded sedimentary landscape was once an ancient seabed later overlaid with volcanic activity.

  7. Strain Engineering of Phosphorene via Bending

    NASA Astrophysics Data System (ADS)

    Verma, Deepti; Dumitrica, Traian

    Phosphorene (PE) - the newly discovered 2D derivative of Phosphorus - has an inherent band gap and a high current on/off ratio. Manipulating strain in PE films - strain engineering (SE) - will offer the opportunity to further tailor its electronic properties. Using objective boundary conditions (OBC) coupled with density functional tight binding model (DFTB), we calculate bending rigidity of PE and its 2D allotropes by modeling bent PE as large diameter nanotubes (PNTs). OBCs not only allow for drastic reductions in the number of atoms in simulations but also enable simulations of chiral PNTs, which is impossible with periodic boundary conditions. At the same time, the method describes how bending influences the electronic structure. We establish a robust platform for achieving SE for anisotropic 2D films. Using results from our calculations and orthotropic thin shell model we develop equivalent continuum structure (ECS) for PE and its allotropes upon bending. The developed ECS can be used for performing finite element simulations of PE films on substrates.

  8. Forming and Bending of Metal Foams

    NASA Astrophysics Data System (ADS)

    Nebosky, Paul; Tyszka, Daniel; Niebur, Glen; Schmid, Steven

    2004-06-01

    This study examines the formability of a porous tantalum foam, known as trabecular metal (TM). Used as a bone ingrowth surface on orthopedic implants, TM is desirable due to its combination of high strength, low relative density, and excellent osteoconductive properties. This research aims to develop bend and stretch forming as a cost-effective alternative to net machining and EDM for manufacturing thin parts made of TM. Experimentally, bending about a single axis using a wiping die was studied by observing cracking and measuring springback. It was found that die radius and clearance strongly affect the springback properties of TM, while punch speed, embossings, die radius and clearance all influence cracking. Depending on the various combinations of die radius and clearance, springback factor ranged from .70-.91. To examine the affect of the foam microstructure, bending also was examined numerically using a horizontal hexagonal mesh. As the hexagonal cells were elongated along the sheet length, elastic springback decreased. This can be explained by the earlier onset of plastic hinging occurring at the vertices of the cells. While the numerical results matched the experimental results for the case of zero clearance, differences at higher clearances arose due to an imprecise characterization of the post-yield properties of tantalum. By changing the material properties of the struts, the models can be modified for use with other open-cell metallic foams.

  9. Controlled impact demonstration airframe bending bridges

    NASA Technical Reports Server (NTRS)

    Soltis, S. J.

    1986-01-01

    The calibration of the KRASH and DYCAST models for transport aircraft is discussed. The FAA uses computer analysis techniques to predict the response of controlled impact demonstration (CID) during impact. The moment bridges can provide a direct correlation between the predictive loads or moments that the models will predict and what was experienced during the actual impact. Another goal is to examine structural failure mechanisms and correlate with analytical predictions. The bending bridges did achieve their goals and objectives. The data traces do provide some insight with respect to airframe loads and structural response. They demonstrate quite clearly what's happening to the airframe. A direct quantification of metal airframe loads was measured by the moment bridges. The measured moments can be correlated with the KRASH and DYCAST computer models. The bending bridge data support airframe failure mechanisms analysis and provide residual airframe strength estimation. It did not appear as if any of the bending bridges on the airframe exceeded limit loads. (The observed airframe fracture was due to the fuselage encounter with the tomahawk which tore out the keel beam.) The airframe bridges can be used to estimate the impact conditions and those estimates are correlating with some of the other data measurements. Structural response, frequency and structural damping are readily measured by the moment bridges.

  10. Probe of local impurity states by bend resistance measurements in graphene cross junctions

    NASA Astrophysics Data System (ADS)

    Du, J.; Li, J. Y.; Kang, N.; Lin, Li; Peng, Hailin; Liu, Zhongfan; Xu, H. Q.

    2016-06-01

    We report on low-temperature transport measurements on four-terminal cross junction devices fabricated from high-quality graphene grown by chemical vapor deposition. At high magnetic fields, the bend resistance reveals pronounced peak structures at the quantum Hall plateau transition, which can be attributed to the edge state transport through the junctions. We further demonstrate that the bend resistance is drastically affected by the presence of local impurity states in the junction regions, and exhibits an unusual asymmetric behavior with respect to the magnetic field direction. The observations can be understood in a model taking into account the combination of the edge transport and an asymmetric scatterer. Our results demonstrate that a graphene cross junction may serve as a sensitive probe of local impurity states in graphene at the nanoscale.

  11. Probe of local impurity states by bend resistance measurements in graphene cross junctions.

    PubMed

    Du, J; Li, J Y; Kang, N; Lin, Li; Peng, Hailin; Liu, Zhongfan; Xu, H Q

    2016-06-17

    We report on low-temperature transport measurements on four-terminal cross junction devices fabricated from high-quality graphene grown by chemical vapor deposition. At high magnetic fields, the bend resistance reveals pronounced peak structures at the quantum Hall plateau transition, which can be attributed to the edge state transport through the junctions. We further demonstrate that the bend resistance is drastically affected by the presence of local impurity states in the junction regions, and exhibits an unusual asymmetric behavior with respect to the magnetic field direction. The observations can be understood in a model taking into account the combination of the edge transport and an asymmetric scatterer. Our results demonstrate that a graphene cross junction may serve as a sensitive probe of local impurity states in graphene at the nanoscale. PMID:27159926

  12. 76 FR 81992 - PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ... COMMISSION PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption 1.0..., Certifications, and Approvals for Nuclear Power Plants.'' This reactor is to be identified as Bell Bend Nuclear... application is based upon the U.S. EPR reference COL (RCOL) application for UniStar's Calvert Cliffs...

  13. Theory of magnetoelectric effect for bending modes in magnetostrictive-piezoelectric bilayers

    NASA Astrophysics Data System (ADS)

    Petrov, V. M.; Srinivasan, G.; Bichurin, M. I.; Galkina, T. A.

    2009-03-01

    In a magnetostrictive-piezoelectric bilayer the interaction between the magnetic and electric subsystems occurs through mechanical deformation. A model is discussed here for the resonance enhancement of such magnetoelectric (ME) interactions at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The frequency dependence for longitudinal and transverse ME voltage coefficients have obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end. It is shown that the bending resonance and consequent enhancement in ME coupling occurs at the lowest frequency for a bilayer that is fixed at one end and free at the other end. The model is applied to a specific case of permendur-lead zinconate titanate bilayer. The theory is in very good agreement with representative data.

  14. Design of a 90{degree} overmoded waveguide bend

    SciTech Connect

    Nantista, C.; Kroll, N.M.; Nelson, E.M.

    1993-04-01

    A design for a 90{degree} bend for the TE{sub 01} mode in over-moded circular waveguide is presented. A pair of septa, symmetrically placed perpendicular to the plane of the bend, are adiabatically introduced into the waveguide before the bend and removed after it. Introduction of the curvature excites five propagating modes in the curved section. The finite element field solver YAP is used to calculate the propagation constants of these modes in the bend, and the guide diameter, septum depth, septum thickness, and bend radius are set so that the phase advances of all five modes through the bend are equal modulo 2{pi}. To a good approximation these modes are expected to recombine to form a pure mode at the end of the bend.

  15. Characterization of bending loss in hollow flexible terahertz waveguides.

    PubMed

    Doradla, Pallavi; Joseph, Cecil S; Kumar, Jayant; Giles, Robert H

    2012-08-13

    Attenuation characteristics of hollow, flexible, metal and metal/dielectric coated polycarbonate waveguides were investigated using an optically pumped far infrared (FIR) laser at 215 µm. The bending loss of silver coated polycarbonate waveguides were measured as a function of various bending angles, bending radii, and bore diameters. Minimal propagation losses of 1.77, 0.96 dB/m were achieved by coupling the lowest loss TE11 mode into the silver or gold coated waveguide, and HE11 mode into the silver/polystyrene coated waveguides respectively. The maximal bending loss was found to be less than 1 dB/m for waveguides of 2 to 4.1 mm bore diameters, with a 6.4 cm bend radius, and up to 150° bending angle. The investigation shows the preservation of single laser mode in smaller bore waveguides even at greater bending angles. PMID:23038558

  16. Evolving efficiency of restraining bends within wet kaolin analog experiments

    NASA Astrophysics Data System (ADS)

    Hatem, Alexandra E.; Cooke, Michele L.; Madden, Elizabeth H.

    2015-03-01

    Restraining bends along strike-slip fault systems evolve by both propagation of new faults and abandonment of fault segments. Scaled analog modeling using wet kaolin allows for qualitative and quantitative observations of this evolution. To explore how bend geometry affects evolution, we model bends with a variety of initial angles, θ, from θ = 0° for a straight fault to θ = 30°. High-angle restraining bends (θ ≥ 20°) overcome initial inefficiencies by abandoning unfavorably oriented restraining segments and propagating multiple new, inwardly dipping, oblique-slip faults that are well oriented to accommodate convergence within the bend. Restraining bends with 0° < θ ≤ 15° maintain activity along the restraining bend segment and grow a single new oblique slip fault on one side of the bend. In all restraining bends, the first new fault propagates at ~5 mm of accumulated convergence. Particle Image Velocimetry analysis provides a complete velocity field throughout the experiments. From these data, we quantify the strike-slip efficiency of the system as the percentage of applied plate-parallel velocity accommodated as slip in the direction of plate motion along faults within the restraining bend. Bends with small θ initially have higher strike-slip efficiency compared to bends with large θ. Although they have different fault geometries, all systems with a 5 cm bend width reach a steady strike-slip efficiency of 80% after 50 mm of applied plate displacement. These experimental restraining bends resemble crustal faults in their asymmetric fault growth, asymmetric topographic gradient, and strike-slip efficiency.

  17. Cricket antennae shorten when bending (Acheta domesticus L.)

    PubMed Central

    Loudon, Catherine; Bustamante, Jorge; Kellogg, Derek W.

    2014-01-01

    Insect antennae are important mechanosensory and chemosensory organs. Insect appendages, such as antennae, are encased in a cuticular exoskeleton and are thought to bend only between segments or subsegments where the cuticle is thinner, more flexible, or bent into a fold. There is a growing appreciation of the dominating influence of folds in the mechanical behavior of a structure, and the bending of cricket antennae was considered in this context. Antennae will bend or deflect in response to forces, and the resulting bending behavior will affect the sensory input of the antennae. In some cricket antennae, such as in those of Acheta domesticus, there are a large number (>100) of subsegments (flagellomeres) that vary in their length. We evaluated whether these antennae bend only at the joints between flagellomeres, which has always been assumed but not tested. In addition we questioned whether an antenna undergoes a length change as it bends, which would result from some patterns of joint deformation. Measurements using light microscopy and SEM were conducted on both male and female adult crickets (Acheta domesticus) with bending in four different directions: dorsal, ventral, medial, and lateral. Bending occurred only at the joints between flagellomeres, and antennae shortened a comparable amount during bending, regardless of sex or bending direction. The cuticular folds separating antennal flagellomeres are not very deep, and therefore as an antenna bends, the convex side (in tension) does not have a lot of slack cuticle to “unfold” and does not lengthen during bending. Simultaneously on the other side of the antenna, on the concave side in compression, there is an increasing overlap in the folded cuticle of the joints during bending. Antennal shortening during bending would prevent stretching of antennal nerves and may promote hemolymph exchange between the antenna and head. PMID:25018734

  18. Contribution of Elasticity in Slab Bending

    NASA Astrophysics Data System (ADS)

    Fourel, L.; Goes, S. D. B.; Morra, G.

    2014-12-01

    Previous studies have shown that plate rheology exerts a dominant control on the shape and velocity of subducting plates. Here, we perform a systematic investigation of the, often disregarded, role of elasticity in slab bending at the trench, using simple, yet fully dynamic, set of 2.5D models where an elastic, visco-elastic or visco-elasto-plastic plate subducts freely into a purely viscous mantle. We derive a scaling relationship between the bending radius of visco-elastic slabs and the Deborah number, De, which is the ratio of Maxwell time over deformation time. We show that De controls the ratio of elastically stored energy over viscously dissipated energy and find that at De exceeding 10-2, it requires substantially less energy to bend a visco-elastic slab to the same shape as a purely viscous slab with the same viscosity (90% less for De=0.1). Elastically stored energy at higher De facilitates slab unbending and hence favours retreating modes of subduction, while trench advance only occurs for some cases with De<10-2. We use our scaling relation to estimate apparent Deborah numbers, Deapp, from a global compilation of subduction-zone parameters. Values range from 10-3 to >1, where most zones have low Deapp<10-2, but a few young plates have Deapp>0.1. Slabs with Deapp ≤ 10-2 either have very low viscosities, ≤10 times mantle viscosity, or they may be yielding, in which case our apparent Deborah number may underestimate actual De by up to an order of magnitude. If a significant portion of the low Deapp slabs yield, then elastically stored energy may actually be important in quite a large number of subduction zones. Interestingly, increasing Deapp correlates with increasing proportion of larger seismic events (b-value) in both instrumental and historic catalogues, indicating that increased contribution of elasticity may facilitate rupture in larger, less frequent earthquakes.

  19. Great Bend tornadoes of August 30, 1974

    NASA Technical Reports Server (NTRS)

    Umenhofer, T. A.; Fujita, T. T.; Dundas, R.

    1977-01-01

    Photogrammetric analyses of movies and still pictures taken of the Great Bend, Kansas Tornado series have been used to develop design specifications for nuclear power plants and facilities. A maximum tangential velocity of 57 m/sec and a maximum vertical velocity of 27 m/sec are determined for one suction vortex having a translational velocity of 32 m/sec. Three suction vortices with radii in the 20 to 30 m range are noted in the flow field of one tornado; these suction vortices apparently form a local convergence of inflow air inside the outer portion of the tornado core.

  20. Self-bending symmetric cusp beams

    SciTech Connect

    Gong, Lei; Liu, Wei-Wei; Lu, Yao; Li, Yin-Mei; Ren, Yu-Xuan

    2015-12-07

    A type of self-bending symmetric cusp beams with four accelerating intensity maxima is theoretically and experimentally presented. Distinguished from the reported regular polygon beams, the symmetric cusp beams simultaneously exhibit peculiar features of natural autofocusing and self-acceleration during propagation. Further, such beams take the shape of a fine longitudinal needle-like structure at the focal region and possess the strong ability of self-healing over obstacles. All these intriguing properties were verified experimentally. Particularly, the spatial profile of the reconstructed beam exhibits spatially sculpted optical structure with four siamesed curved arms. Thus, we anticipate that the structured beam will benefit optical guiding and optofluidics in surprising ways.

  1. Self-bending symmetric cusp beams

    NASA Astrophysics Data System (ADS)

    Gong, Lei; Liu, Wei-Wei; Ren, Yu-Xuan; Lu, Yao; Li, Yin-Mei

    2015-12-01

    A type of self-bending symmetric cusp beams with four accelerating intensity maxima is theoretically and experimentally presented. Distinguished from the reported regular polygon beams, the symmetric cusp beams simultaneously exhibit peculiar features of natural autofocusing and self-acceleration during propagation. Further, such beams take the shape of a fine longitudinal needle-like structure at the focal region and possess the strong ability of self-healing over obstacles. All these intriguing properties were verified experimentally. Particularly, the spatial profile of the reconstructed beam exhibits spatially sculpted optical structure with four siamesed curved arms. Thus, we anticipate that the structured beam will benefit optical guiding and optofluidics in surprising ways.

  2. Bending of light in quantum gravity.

    PubMed

    Bjerrum-Bohr, N E J; Donoghue, John F; Holstein, Barry R; Planté, Ludovic; Vanhove, Pierre

    2015-02-13

    We consider the scattering of lightlike matter in the presence of a heavy scalar object (such as the Sun or a Schwarzschild black hole). By treating general relativity as an effective field theory we directly compute the nonanalytic components of the one-loop gravitational amplitude for the scattering of massless scalars or photons from an external massive scalar field. These results allow a semiclassical computation of the bending angle for light rays grazing the Sun, including long-range ℏ contributions. We discuss implications of this computation, in particular, the violation of some classical formulations of the equivalence principle. PMID:25723201

  3. Mixed-Mode-Bending Delamination Apparatus

    NASA Technical Reports Server (NTRS)

    Crews, John H., Jr.; Reeder, James R.

    1991-01-01

    Mixed-mode-bending delamination apparatus generates two types of delamination stress simultaneously in specimen from single externally applied point load. In technique, indivial mode I and mode II contributions to delamination in specimen analyzed by use of simple beam-theory equations, eliminating need for time-consuming, difficult numerical analysis. Allows wider range of mode I/mode II ratios than possible with many other methods. Mixed-mode delamination testing of interest in all fields utilizing composite materials, used mostly in aerospace field, but also used in automobiles, lightweight armored military vehicles, boats, and sporting equipment. Useful in general lumber, plywood, and adhesive industries, as well.

  4. Bending and buckling of wet paper

    NASA Astrophysics Data System (ADS)

    Lee, Minhee; Kim, Seungho; Kim, Ho-Young; Mahadevan, L.

    2016-04-01

    Flat paper stained with water buckles and wrinkles as it swells and deforms out of the original plane. Here we quantify the geometry and mechanics of a strip of paper that swells when it imbibes water from a narrow capillary. Characterizing the hygroexpansive nature of paper shows that thickness-wise swelling is much faster than in-plane water imbibition, leading to a simple picture for the process by which the strip of paper bends out of the plane. We model the out-of-plane deformation using a quasi-static theory and show that our results are consistent with quantitative experiments.

  5. Quasi-static characterization and modeling of the bending behavior of single crystal galfenol for magnetostrictive sensors and actuators

    NASA Astrophysics Data System (ADS)

    Datta, Supratik

    2009-12-01

    Iron-gallium alloys (Galfenol) are structural magnetostrictive materials that exhibit high free-strain at low magnetic fields, high stress-sensitivity and useful thermo-mechanical properties. Galfenol, like smart materials in general, is attractive for use as a dynamic actuator and/or sensor material and can hence find use in active shape and vibration control, real-time structural health monitoring and energy harvesting applications. Galfenol possesses significantly higher yield strength and greater ductility than most smart materials, which are generally limited to use under compressive loads. The unique structural attributes of Galfenol introduce opportunities for use of a smart material in applications that involve tension, bending, shear or torsion. A principal motivation for the research presented in this dissertation is that bending and shear loads lead to development of non-uniform stress and magnetic fields in Galfenol which introduce significantly more complexity to the considerations to be modeled, compared to modeling of purely axial loads. This dissertation investigates the magnetostrictive response of Galfenol under different stress and magnetic field conditions which is essential for understanding and modeling Galfenol's behavior under bending, shear or torsion. Experimental data are used to calculate actuator and sensor figures of merit which can aid in design of adaptive structures. The research focuses on the bending behavior of Galfenol alloys as well as of laminated composites having Galfenol attached to other structural materials. A four-point bending test under magnetic field is designed, built and conducted on a Galfenol beam to understand its performance as a bending sensor. An extensive experimental study is conducted on Galfenol-Aluminum laminated composites to evaluate the effect of magnetic field, bending moment and Galfenol-Aluminum thickness ratio on actuation and sensing performance. A generalized recursive algorithm is presented for

  6. Design of a multi-bend achromat lattice for 3 GeV synchrotron light source

    NASA Astrophysics Data System (ADS)

    Kim, Eun-San

    2016-03-01

    We present a lattice design for a low-emittance and high-brilliance 3 GeV synchrotron light source that has been widely investigated in the world. We show the design results for a MBA (Multi-Bend Achromat) lattice with an emittance of 1.3 nm and 282.4 m circumference. Each cell has 5 bending magnets that consist of outer two with bending angle of 4.5° and inner three with bending angle of 7°. The lattice is designed to be flexible and consists of 12 straight sections in which one straight section has a length of 5.9 m. We have studied the dynamic aperture in the lattice with machine errors. It is shown that the designed low-emittance lattice provides sufficient dynamic aperture after COD correction. We present the results of variations of emittance, energy spread and dynamic aperture due to in-vacuum undulators in the straight sections. We performed particle tracking after the beam injection to investigate the efficiency of the injection scheme. We show the designed results of an injection scheme that shows the space allocation in injection section and the particle motions of injected beam. Our designed lattice provides a good optimization in terms of the emittance and brilliance as a light source for 3 GeV energy and circumference of 28 m.

  7. Magnetic

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  8. Multifiber optical bend sensor to aid colonoscope navigation

    NASA Astrophysics Data System (ADS)

    Kesner, Jessica E.; Gavalis, Robb M.; Wong, Peter Y.; Cao, Caroline G. L.

    2011-12-01

    A colonoscopy's near-blind navigation process frequently causes disorientation for the scope operator, leading to harm for the patient. Navigation can be improved if real-time colonoscope shape, location, and orientation information is provided by a shape-tracking aid, such as a fiber optic bend sensor. Fiber optic bend sensors provide advantages over conventional electromechanical shape-trackers, including low cost and ease of integration. However, current fiber optic bend sensors lack either the ability to detect both bending direction and curvature, or the ability to detect multiple localized bends. An inexpensive multifiber bend sensor was developed to aid users in navigation during colonoscopy. The bend sensor employs active-cladding optical fibers modified with fluorescent quantum dots, bandpass filters, and a complementary metal-oxide-semiconductor imager as key components. Results from three-fiber sensors demonstrate the bend sensor's ability to measure curvature (error of 0.01 mm), direction (100% accuracy), and location (predetermined distance) of a bend in the fiber bundle. Comparison with spectroscopy data further confirmed the accuracy of the bending direction measurement for a three-fiber sensor. Future work includes improvements in fiber manufacturing to increase sensor sensitivity and consistency. An expanded 31 fiber bundle would be needed to track the full length of a colonoscope.

  9. The design of an agent to bend DNA.

    PubMed Central

    Akiyama, T; Hogan, M E

    1996-01-01

    An artificial DNA bending agent has been designed to assess helix flexibility over regions as small as a protein binding site. Bending was obtained by linking a pair of 15-base-long triple helix forming oligonucleotides (TFOs) by an adjustable polymeric linker. By design, DNA bending was introduced into the double helix within a 10-bp spacer region positioned between the two sites of 15-base triple helix formation. The existence of this bend has been confirmed by circular permutation and phase-sensitive electrophoresis, and the directionality of the bend has been determined as a compression of the minor helix groove. The magnitude of the resulting duplex bend was found to be dependent on the length of the polymeric linker in a fashion consistent with a simple geometric model. Data suggested that a 50-70 degrees bend was achieved by binding of the TFO chimera with the shortest linker span (18 rotatable bonds). Equilibrium analysis showed that, relative to a chimera which did not bend the duplex, the stability of the triple helix possessing a 50-70 degrees bend was reduced by less than 1 kcal/mol of that of the unbent complex. Based upon this similarity, it is proposed that duplex DNA may be much more flexible with respect to minor groove compression than previously assumed. It is shown that this unusual flexibility is consistent with recent quantitation of protein-induced minor groove bending. Images Fig. 2 Fig. 3 PMID:8901543

  10. Nonlinear Bending Stiffness of Plates Clamped by Bolted Joints under Bending Moment

    NASA Astrophysics Data System (ADS)

    Naruse, Tomohiro; Shibutani, Yoji

    Equivalent stiffness of plates clamped by bolted joints for designing should be evaluated according to not only the strength of bolted joints but also the deformation and vibration characteristics of the structures. When the applied external axial load or the bending moment is sufficiently small, the contact surfaces of the bolted joint are stuck together, and thus both the bolt and the clamped plates deform linearly. Although the sophisticated VDI 2230 code gives the appropriate stiffness of clamped plates for the infinitesimal deformation, the stiffness may vary nonlinearly with increasing the loading because of changing the contact state. Therefore, the present paper focuses on the nonlinear behaviour of the bending stiffness of clamped plates by using Finite Element (FE) analyses, taking the contact condition on bearing surfaces and between the plates into account. The FE models of the plates with thicknesses of 3.2, 4.5, 6.0 and 9.0 mm tightened with M8, 10, 12 and 16 bolts were constructed. The relation between bending moment and bending compliance of clamped plates is found to be categorized into three regions, namely, (i) constant compliance with fully stuck contact surfaces, (ii) transition showing the nonlinear compliance, and (iii) constant compliance with one-side contact surfaces. The mechanical models for these three regions are proposed and compared with FEM solutions. The prediction on the bounds of three regions is in a fairly good agreement except the case with smaller bolts and thicker plates.

  11. Guided Wave Travel Time Tomography for Bends

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Bloom, Joost

    2011-06-01

    The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography has been developed to map the wall thickness using the travel times of guided waves. The method has been demonstrated for straight pipes. The extension of this method to bends is not straightforward because natural focusing occurs due to geometrical path differences. This yields a phase jump, which complicates travel time picking. Because ray-tracing is no longer sufficient to predict the travel times a recursive wave field extrapolation has been developed. The method uses a short spatial convolution operator to propagate a wave field through a bend. The method allows to calculate the wave field at the detector ring, including the phase jump as a consequence of the natural focusing. The recursive wave field extrapolation is done in the space-frequency domain. Therefore dispersion effects can be included easily in the forward modeling. Comparison with measurements shows the accuracy of the method.

  12. Characterization of bending magnetostriction in iron-gallium alloys for nanowire sensor applications

    NASA Astrophysics Data System (ADS)

    Downey, Patrick Ramon

    This research explores the possibility of using electrochemically deposited nanowires of magnetostrictive iron-gallium (Galfenol) to mimic the sensing capabilities of biological cilia. Sensor design calls for incorporating Galfenol nanowires cantilevered from a membrane and attached to a conventional magnetic field sensor. As the wires deflect in response to acoustic, air flow, or tactile excitation, the resultant bending stresses induce changes in magnetization that due to the scale of the nanowires offer the potential for excellent spatial resolution and frequency bandwidth. In order to determine the suitability for using Galfenol nanowires in this role, the first task was experimentally characterizing magnetostrictive transduction in bending beam structures, as this means of operation has been unattainable in previous materials research due to low tensile strengths in conventional alloys such as Terfenol-D. Results show that there is an appreciable sensing response from cantilevered Galfenol beams and that this phenomenon can be accurately modeled with an energy based formulation. For progressing experiments to the nanowire scale, a nanomanipulation instrument was designed and constructed that interfaces within a scanning electron microscope and allows for real time characterization of individual wires with diameters near 100 nm. The results of mechanical tensile testing and dynamic resonance identification reveal that the Galfenol nanowires behave similarly to the bulk material with the exception of a large increase in ultimate tensile strength. The magnetic domain structure of the nanowires was theoretically predicted and verified with magnetic force microscopy. An experimental methodology was developed to observe the coupling between bending stress and magnetization that is critical for accurate sensing, and the key results indicate that specific structural modifications need to be made to reduce the anisotropy in the nanowires in order to improve the

  13. Precision Small Angle Bending of Sheet Metals Using Shear Deformation

    NASA Astrophysics Data System (ADS)

    Hirota, Kenji; Mori, Yorifumi

    This paper deals with a new method to bend sheet metals at a small angle precisely, in which a sheet metal is slightly bent by shear deformation at negative punch-die clearance. Deformation behavior and key factors affecting on the bend angle were studied in detail with pure aluminum sheets. It was proved that the bend angle was changed in proportion to both punch penetration and negative punch-die clearance within a certain range. The same was true for high-strength steel and phosphor bronze, which are difficult to bend precisely by conventional methods due to large springback after unloading. By using this relationship as a control law, four kinds of sheet metals were precisely bent within a few degrees. This method was applied to correct the angular errors in U-bend products of high-strength steel and to bend leaf springs of phosphor bronze at an arbitrary small angle.

  14. Bending strain tolerance of MgB2 superconducting wires

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kulich, M.; Kopera, L.

    2016-04-01

    This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. I c-bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.

  15. Transient Pinning and Pulling: A Mechanism for Bending Microtubules.

    PubMed

    Kent, Ian A; Rane, Parag S; Dickinson, Richard B; Ladd, Anthony J C; Lele, Tanmay P

    2016-01-01

    Microtubules have a persistence length of the order of millimeters in vitro, but inside cells they bend over length scales of microns. It has been proposed that polymerization forces bend microtubules in the vicinity of the cell boundary or other obstacles, yet bends develop even when microtubules are polymerizing freely, unaffected by obstacles and cell boundaries. How these bends are formed remains unclear. By tracking the motions of microtubules marked by photobleaching, we found that in LLC-PK1 epithelial cells local bends develop primarily by plus-end directed transport of portions of the microtubule contour towards stationary locations (termed pinning points) along the length of the microtubule. The pinning points were transient in nature, and their eventual release allowed the bends to relax. The directionality of the transport as well as the overall incidence of local bends decreased when dynein was inhibited, while myosin inhibition had no observable effect. This suggests that dynein generates a tangential force that bends microtubules against stationary pinning points. Simulations of microtubule motion and polymerization accounting for filament mechanics and dynein forces predict the development of bends of size and shape similar to those observed in cells. Furthermore, simulations show that dynein-generated bends at a pinning point near the plus end can cause a persistent rotation of the tip consistent with the observation that bend formation near the tip can change the direction of microtubule growth. Collectively, these results suggest a simple physical mechanism for the bending of growing microtubules by dynein forces accumulating at pinning points. PMID:26974838

  16. Bending response of single layer MoS2.

    PubMed

    Xiong, Si; Cao, Guoxin

    2016-03-11

    Using molecular mechanics (or dynamics) simulations, three different approaches, including the targeted molecular mechanics, four-point bending and nanotube methods, are employed to investigate the bending response of single layer MoS2 (SLMoS2), among which four-point bending is the most accurate approach to determine the bending stiffness according to the continuum theory. It is found that when the bending curvature radius is large enough (e.g. >4 nm), three approaches will give the same bending stiffness of SLMoS2 and the bending behavior is isotropic for SLMoS2, whereas the nanotube method with small tubes (e.g. <4 nm) cannot give the correct bending stiffness. Compared with the reported result from the MoS2 nanotube calculated by density functional theory, the revised Stillinger-Weber (SW) and reactive empirical bond-order (REBO) potentials can give the reasonable bending stiffness of SLMoS2 (8.7-13.4 eV) as well as the effective deformed conformation. In addition, since the Mo-S bond deformation of SLMoS2 under bending is similar to that under in-plane tension/compression, the continuum bending theory can quite accurately predict the bending stiffness of SLMoS2 if a reasonable thickness of SLMoS2 is given. For SLMoS2, the reasonable thickness should be larger than the distance between its two S atomic planes and lower than the distance between two Mo atomic planes of bulk MoS2 crystal, e.g. 0.375-0.445 nm. PMID:26861930

  17. The mechanics of gravitropic bending in leafy dicot stems

    NASA Technical Reports Server (NTRS)

    Salisbury, F. B.; Mueller, W. J.; Blotter, P. T.; Harris, C. S.; White, R. G.; Gillespie, L. S.; Sliwinski, J. E.

    1982-01-01

    The mechanism of the gravitropic bending in stems of the cocklebur and castor bean are investigated. The results of these experiments demonstrate the quick stopping of growth and the increased tensions on the upper layer of a horizontal stem. It is suggested that bending apparently occurs as the resistance of the upper surface layers is extended to the inner cells below. A model of stem bending is developed which can explain the asymmetry of the stem-cell response.

  18. Transient Pinning and Pulling: A Mechanism for Bending Microtubules

    PubMed Central

    Kent, Ian A.; Rane, Parag S.; Dickinson, Richard B.; Ladd, Anthony J. C.; Lele, Tanmay P.

    2016-01-01

    Microtubules have a persistence length of the order of millimeters in vitro, but inside cells they bend over length scales of microns. It has been proposed that polymerization forces bend microtubules in the vicinity of the cell boundary or other obstacles, yet bends develop even when microtubules are polymerizing freely, unaffected by obstacles and cell boundaries. How these bends are formed remains unclear. By tracking the motions of microtubules marked by photobleaching, we found that in LLC-PK1 epithelial cells local bends develop primarily by plus-end directed transport of portions of the microtubule contour towards stationary locations (termed pinning points) along the length of the microtubule. The pinning points were transient in nature, and their eventual release allowed the bends to relax. The directionality of the transport as well as the overall incidence of local bends decreased when dynein was inhibited, while myosin inhibition had no observable effect. This suggests that dynein generates a tangential force that bends microtubules against stationary pinning points. Simulations of microtubule motion and polymerization accounting for filament mechanics and dynein forces predict the development of bends of size and shape similar to those observed in cells. Furthermore, simulations show that dynein-generated bends at a pinning point near the plus end can cause a persistent rotation of the tip consistent with the observation that bend formation near the tip can change the direction of microtubule growth. Collectively, these results suggest a simple physical mechanism for the bending of growing microtubules by dynein forces accumulating at pinning points. PMID:26974838

  19. BEND3 mediates transcriptional repression and heterochromatin organization.

    PubMed

    Khan, Abid; Prasanth, Supriya G

    2015-01-01

    Transcription repression plays a central role in gene regulation. Transcription repressors utilize diverse strategies to mediate transcriptional repression. We have recently demonstrated that BEND3 (BANP, E5R and Nac1 domain) protein represses rDNA transcription by stabilizing a NoRC component. We discuss the role of BEND3 as a global regulator of gene expression and propose a model whereby BEND3 associates with chromatin remodeling complexes to modulate gene expression and heterochromatin organization. PMID:26507581

  20. Compliance measurements of chevron notched four point bend specimen

    NASA Technical Reports Server (NTRS)

    Calomino, Anthony; Bubsey, Raymond; Ghosn, Louis J.

    1994-01-01

    The experimental stress intensity factors for various chevron notched four point bend specimens are presented. The experimental compliance is verified using the analytical solution for a straight through crack four point bend specimen and the boundary integral equation method for one chevron geometry. Excellent agreement is obtained between the experimental and analytical results. In this report, stress intensity factors, loading displacements and crack mouth opening displacements are reported for different crack lengths and different chevron geometries, under four point bend loading condition.

  1. Bending response of single layer MoS2

    NASA Astrophysics Data System (ADS)

    Xiong, Si; Cao, Guoxin

    2016-03-01

    Using molecular mechanics (or dynamics) simulations, three different approaches, including the targeted molecular mechanics, four-point bending and nanotube methods, are employed to investigate the bending response of single layer MoS2 (SLMoS2), among which four-point bending is the most accurate approach to determine the bending stiffness according to the continuum theory. It is found that when the bending curvature radius is large enough (e.g. >4 nm), three approaches will give the same bending stiffness of SLMoS2 and the bending behavior is isotropic for SLMoS2, whereas the nanotube method with small tubes (e.g. <4 nm) cannot give the correct bending stiffness. Compared with the reported result from the MoS2 nanotube calculated by density functional theory, the revised Stillinger-Weber (SW) and reactive empirical bond-order (REBO) potentials can give the reasonable bending stiffness of SLMoS2 (8.7-13.4 eV) as well as the effective deformed conformation. In addition, since the Mo-S bond deformation of SLMoS2 under bending is similar to that under in-plane tension/compression, the continuum bending theory can quite accurately predict the bending stiffness of SLMoS2 if a reasonable thickness of SLMoS2 is given. For SLMoS2, the reasonable thickness should be larger than the distance between its two S atomic planes and lower than the distance between two Mo atomic planes of bulk MoS2 crystal, e.g. 0.375-0.445 nm.

  2. Static Fatigue of Optical Fibers in Bending

    NASA Astrophysics Data System (ADS)

    Roberts, D.; Cuellar, E.; Middleman, L.; Zucker, J.

    1987-02-01

    While delayed fracture, or static fatigue, of optical fibers is well known, it is not well understood, and the prediction of the time to failure under a given set of conditions can be problematic. Unlike short term fracture, which is quite well understood and quantified in terms of the theory of linear elastic fracture mechanics, the long term strength remains empirical. The goal of this study is to determine the design criteria for optical fibers subjected to long term applied mechanical loads. One difficulty in making lifetime predictions, as pointed out by Matthewson (Reference 1) and others, is that predictions made from data taken in tension and in bending do not agree. Another difficulty is the statistical nature of the fracture of glass. In making lifetime predictions it becomes important therefore that one (a) have ample data for statistical analysis and (b) have data for the loading configuration of interest. This is the purpose of our work. Since there is less data available in bending, and since several applications (such as wiring in aircraft and missiles) require bending, the data are taken in that configuration. The most significant finding in our work so far is the very large difference in static fatigue behavior between buffer coatings. Chandan and Kalish (Reference 2) and others have reported static fatigue curves, log (time to failure) versus log (applied stress), which are not linear, but rather bimodal. Our study confirms this result, but so far only for acrylate coated fibers. Silicone coated fibers show unimodal behavior. That is, the log (time to failure) versus log (applied stress) curve is linear, at least on the time scale studied so far. Data for acrylate coated fibers at 80°C in water are linear only for time scales of about one day, where a pronounced "knee" is observed. Data for silicone coated fibers under the same conditions are linear up to at least 6 months. Longer time scale tests and tests on fibers with other buffer materials

  3. PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING

    SciTech Connect

    Harbour, J; Tommy Edwards, T; Vickie Williams, V

    2008-01-30

    One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10{sup -9} cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for

  4. Bending waves and the structure of Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.

    1985-01-01

    The surface mass density profiles at four locations within Saturn's rings are calculated using Voyager spacecraft images of spiral bending waves. The identification of a feature in Saturn's outer B ring as Mimas's 4:2 bending waves is confirmed, and these 4:2 waves are analyzed to determine the surface density in Saturn's B ring. A fourth set of bending waves, the Mimas 7:4, located in the inner A ring, is identified and analyzed. Mimas's 5:3 and 8:5 bending waves, observed in the middle and outer A ring respectively, are reanalyzed.

  5. GENERAL VIEW OF TUMALO FEED CANAL (RIGHT) AND BEND FEED ...

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

    GENERAL VIEW OF TUMALO FEED CANAL (RIGHT) AND BEND FEED CANAL (LEFT) INTERSECTION. LOOKING SOUTHEAST - Tumalo Irrigation District, Tumalo Project, West of Deschutes River, Tumalo, Deschutes County, OR

  6. Sorting of bed load sediment by flow in meander bends.

    USGS Publications Warehouse

    Parker, G.; Andrews, E.D.

    1985-01-01

    Equilibrium sorting of coarse mobile bed load sediment in meander bends is considered. A theory of two-dimensional bed load transport of graded material, including the effects of gravity on lateral slopes and secondary currents, is developed. This theory is coupled with a simple tratement of flow in bends, an analytically determined bend shape, and the condition of continuity of each grain size range in transport to describe sorting. The theory indicates that the locus of coarse sediment shifts from the inside bank to the outside bank near the bend apex, as is observed.-Authors

  7. Adaptive waveguide bends with homogeneous, nonmagnetic, and isotropic materials.

    PubMed

    Han, Tiancheng; Qiu, Cheng-Wei; Tang, Xiaohong

    2011-01-15

    We propose a method for adaptive waveguide bends using homogeneous, nonmagnetic, and isotropic materials, which simplifies the parameters of the bends to the utmost extent. The proposed bend has an adaptive and compact shape because of all the flat boundaries. The nonmagnetic property is realized by selecting OB'/OC = 0.5. Only two nonmagnetic isotropic dielectrics are needed throughout, and the transmission is not sensitive to nonmagnetic isotropic dielectrics. Results validate and illustrate these functionalities, which make the bend much easier to fabricate and apply, owing to its simple parameters, compact shape, and versatility in connecting different waveguides. PMID:21263493

  8. Fatigue life prediction in bending from axial fatigue information

    NASA Technical Reports Server (NTRS)

    Manson, S. S.; Muralidharan, U.

    1982-01-01

    Bending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress-strain relation normally used to determine the nominal stresses. An approach is presented to take into account the plastic flow in calculating nominal bending stress (S sub bending) based on true surface stress. These functions are derived in closed form for rectangular and circular cross sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life (N sub S) and these curves are shown for several materials of engineering interest.

  9. Transport IV characterisation of MgB2 conductor at a bend radius of 50mm

    NASA Astrophysics Data System (ADS)

    Young, E. A.; Falorio, I.; Beduz, C.; Bailey, W. O. S.; Yang, Y.

    2014-05-01

    Performance of state of the art MgB2 multifilamentary conductor at a required bend radius is essential for many applications including but not limited to magnets and motors. The characterisation is generally done with benchmark transport Ic but further detail can be seen in IV characteristics which are undertaken in this paper. Two conductors with the same architecture but different diameters, 0.89 and 0.45 mm were measured from 32 K to 20 K in self-field in conditions of as received and deformed to a 50 mm bend diameter, corresponding to strains of 1.4 % and 0.7 % respectively. The qualifying 0.45mm conductor was further measured in background fields up to 3 T. The smaller diameter wire was found to have no signs of degradation of critical behaviour in Ic or IV characteristics.

  10. Superconducting flat tape cable magnet

    DOEpatents

    Takayasu, Makoto

    2015-08-11

    A method for winding a coil magnet with the stacked tape cables, and a coil so wound. The winding process is controlled and various shape coils can be wound by twisting about the longitudinal axis of the cable and bending following the easy bend direction during winding, so that sharp local bending can be obtained by adjusting the twist pitch. Stack-tape cable is twisted while being wound, instead of being twisted in a straight configuration and then wound. In certain embodiments, the straight length should be half of the cable twist-pitch or a multiple of it.

  11. Separation of blood in microchannel bends

    NASA Astrophysics Data System (ADS)

    Blattert, Christoph; Jurischka, Reinhold; Schoth, Andreas; Kerth, Paul; Menz, Wolfgang

    2004-01-01

    Biological applications of micro assay devices require integrated on-chip microfluidics for separation of plasma or serum from blood. This is achieved by a new blood separation technique based on a microchannel bend structure developed within the collaborative Micro-Tele-BioChip (μTBC) project co-funded by the German Ministry For Education and Research (BMBF). Different prototype polymer chips have been manufactured with an UV-LIGA process and hot embossing technology. The separation efficiency of these chips has been determined by experimental measurements using human whole blood. Results show different separation efficiencies for cells and plasma depending on microchannel geometry and blood sample characteristics and suggest an alternative blood separation method as compared to existing micro separation technologies.

  12. Separation of blood in microchannel bends

    NASA Astrophysics Data System (ADS)

    Blattert, Christoph; Jurischka, Reinhold; Schoth, Andreas; Kerth, Paul; Menz, Wolfgang

    2003-12-01

    Biological applications of micro assay devices require integrated on-chip microfluidics for separation of plasma or serum from blood. This is achieved by a new blood separation technique based on a microchannel bend structure developed within the collaborative Micro-Tele-BioChip (μTBC) project co-funded by the German Ministry For Education and Research (BMBF). Different prototype polymer chips have been manufactured with an UV-LIGA process and hot embossing technology. The separation efficiency of these chips has been determined by experimental measurements using human whole blood. Results show different separation efficiencies for cells and plasma depending on microchannel geometry and blood sample characteristics and suggest an alternative blood separation method as compared to existing micro separation technologies.

  13. Bending the Cost Curve in Childhood Cancer.

    PubMed

    Russell, Heidi; Bernhardt, M Brooke

    2016-08-01

    Healthcare for children with cancer costs significantly more than other children. Cost reduction efforts aimed toward relatively small populations of patients that use a disproportionate amount of care, like childhood cancer, could have a dramatic impact on healthcare spending. The aims of this review are to provide stakeholders with an overview of the drivers of financial costs of childhood cancer and to identify possible directions to curb or decrease these costs. Costs are incurred throughout the spectrum of care. Recent trends in pharmaceutical costs, evidence identifying the contribution of administration costs, and overuse of surveillance studies are described. Awareness of cost and value, i.e., the outcome achieved per dollar or burden spent, in delivery of care and research is necessary to bend the cost curve. Incorporation of these dimensions of care requires methodology development, prioritization, and ethical balance. PMID:27193602

  14. A comparison of needle bending models.

    PubMed

    Dehghan, Ehsan; Goksel, Orcun; Salcudean, Septimiu E

    2006-01-01

    Modeling the deflection of flexible needles is an essential part of needle insertion simulation and path planning. In this paper, three models are compared in terms of accuracy in simulating the bending of a prostate brachytherapy needle. The first two utilize the finite element method, one using geometric non-linearity and triangular plane elements, the other using non-linear beam elements. The third model uses angular springs to model cantilever deflection. The simulations are compared with the experimental bent needle configurations. The models are assessed in terms of geometric conformity using independently identified and pre-identified model parameters. The results show that the angular spring model, which is also the simplest, simulates the needle more accurately than the others. PMID:17354904

  15. Pure bending of a solid cone

    NASA Astrophysics Data System (ADS)

    Renton, J. D.

    1997-05-01

    The problems of torsion, axial loading and shear of a solid cone were solved around the turn of the century by Michell and Föppl. Surprisingly, no solution to the problem of the elastic response of a cone to the only other possible resultant applied to its apex seems to have been published until now. The method used here is based on certain theoretical considerations related to the author's work on generalizing the engineering theory of beams. This means that the result is derived rather than being the result of a trial-and-error process. A comparison is made with the usual engineering theory as modified for variable bending stiffness. The two analyses give the same results at the limit as the cone angle tends to zero.

  16. Light bending in f(T) gravity

    NASA Astrophysics Data System (ADS)

    Ruggiero, Matteo Luca

    2016-05-01

    In the framework of f(T) gravity, we focus on a weak-field and spherically symmetric solution for the Lagrangian f(T) = T + αT2, where α is a small constant which parametrizes the departure from general relativity (GR). In particular, we study the propagation of light and obtain the correction to the general relativistic bending angle. Moreover, we discuss the impact of this correction on some gravitational lensing observables, and evaluate the possibility of constraining the theory parameter α by means of observations. In particular, on taking into account the astrometric accuracy in the Solar System, we obtain that |α|≤ 1.85 × 105m2; this bound is looser than those deriving from the analysis of Solar System dynamics, e.g. |α|≤ 5 × 10‑1m2 [L. Iorio, N. Radicella and M. L. Ruggiero, J. Cosmol. Astropart. Phys. 1508 (2015) 021, arXiv:1505.06996 [gr-qc].], |α|≤ 1.8 × 104m2 [L. Iorio and E. N. Saridakis, Mon. Not. R. Astron. Soc. 427 (2012) 1555, arXiv:1203.5781 [gr-qc].] or |α|≤ 1.2 × 102m2 [Y. Xie and X. M. Deng, Mon. Not. R. Astron. Soc. 433 (2013) 3584, arXiv:1312.4103 [gr-qc].]. However, we suggest that, since the effect only depends on the impact parameter, better constraints could be obtained by studying light bending from planetary objects.

  17. A High Power Ultrasonic Linear Motor Using a Longitudinal and Bending Hybrid Bolt-Clamped Langevin Type Transducer

    NASA Astrophysics Data System (ADS)

    Yun, Cheol-Ho; Ishii, Takaaki; Nakamura, Kentaro; Ueha, Sadayuki; Akashi, Koji

    2001-05-01

    A hybrid transducer type ultrasonic linear motor using the 1st longitudinal and the 2nd bending vibration modes of a bolt-clamped Langevin type transducer has been proposed and studied for accomplishing high mechanical output. The longitudinal vibration generates the mechanical driving force and the bending vibration controls the frictional force. To obtain large vibration amplitude and large mechanical output, a method of tuning the longitudinal resonance frequency to the bending one was investigated using finite element simulations, and demonstrated experimentally. To avoid magnetic interaction, we employed phosphor bronze for the bolt of the transducer. The prototype motor achieved the no-load velocity of 0.47 m/s and the maximum output mechanical force of 92 N.

  18. Metamaterial-waveguide bends with effective bend radius < λ₀/2.

    PubMed

    Shen, Bing; Polson, Randy; Menon, Rajesh

    2015-12-15

    We designed, fabricated, and characterized broadband, efficient, all-dielectric metamaterial-waveguide bends (MWBs) that redirect light by 180 deg. The footprint of each MWB is 3  μm×3  μm and redirection is achieved for single-mode waveguides spaced by 1.3 μm, which corresponds to an effective bend radius of 0.65 μm (<λ₀/2 for λ₀=1.55  μm). The designed and measured transmission efficiencies are >80% and ∼70%, respectively. Furthermore, the MWBs have an operating bandwidth >66 nm (design) and >56  nm (experiments). Our design methodology that incorporates fabrication constraints enables highly robust devices. The methodology can be extended to the general routing of light in tight spaces for large-scale photonic integration. PMID:26670503

  19. 36 CFR 7.41 - Big Bend National Park.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Big Bend National Park. 7.41 Section 7.41 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.41 Big Bend National Park. (a) Fishing; closed...

  20. COASTAL BEND BAYS & ESTUARIES PROGRAM IMPLEMENTATION REVIEW 2004

    EPA Science Inventory

    The Coastal Bend Bays & Estuaries Program, Inc. (CBBEP) is a nonprofit 501(c)(3)organization. The CBBEP project area encompasses 12 counties coincident with the Coastal Bend Council of Governments and extends from the Land-Cut in the Laguna Madre, through the Corpus Christi Bay s...

  1. Regulation of transcription by synthetic DNA-bending agents.

    PubMed

    Bednarski, David; Firestine, Steven M

    2006-11-01

    Gene expression is regulated by a complex interplay between binding and the three-dimensional arrangement of transcription factors with RNA polymerase and DNA. Previous studies have supported a direct role for DNA bending and conformation in gene expression, which suggests that agents that induce bends in DNA might be able to control gene expression. To test this hypothesis, we examined the effect of triple-helix-forming oligonucleotide (TFO) bending agents on the transcription of luciferase in an in vitro transcriptional/translational system. We find that transcription is regulated only by a TFO that induces a bend in the DNA. Related TFOs that do not induce bends in DNA have no effect on transcription. Reporter expression can be increased by as much as 80 % or decreased by as much as 50 % depending on the phasing of the upstream bend relative to the promoter. We interpret the results as follows: when the bend is positioned such that the upstream DNA is curved toward the RNA polymerase on the same DNA face, transcription is enhanced. When the upstream DNA is curved away, transcription is attenuated. These results support the hypothesis that DNA-bending agents might have the capability to regulate gene expression, thereby opening up a previously undervalued avenue in research on the artificial control of gene expression. PMID:17004274

  2. General plan, bending machinge, Johnson Company, Johnstown, Pa. Scale 3 ...

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

    General plan, bending machinge, Johnson Company, Johnstown, Pa. Scale 3 inches - 1 ft, March 13th 1893, drawing number 15384 (photograph of drawing of rail bending machine held at the Johnstown Corporation General Office, Johnstown, Pennsylvania) - Johnson Steel Street Rail Company, 525 Central Avenue, Johnstown, Cambria County, PA

  3. View north of tube bending shop in boilermakers department located ...

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

    View north of tube bending shop in boilermakers department located in southeast corner of the structural shop building (building 57). The computer controlled tube bender can be programmed to bend boiler tubing to nearly any required configuration - Naval Base Philadelphia-Philadelphia Naval Shipyard, Structure Shop, League Island, Philadelphia, Philadelphia County, PA

  4. Observation and Modeling of Single Wall Carbon Nanotube Bend Junctions

    NASA Technical Reports Server (NTRS)

    Han, Jie; Anantram, M. P.; Jaffe, R. L.; Kong, J.; Dai, H.; Saini, Subhash (Technical Monitor)

    1998-01-01

    Single wall carbon nanotube (SWNT) bends, with diameters from approx. 1.0 to 2.5 nm and bend angles from 18 deg. to 34 deg., are observed in catalytic decomposition of hydrocarbons at 600 - 1200 C. An algorithm using molecular dynamics simulation (MD) techniques is developed to model these structures that are considered to be SWNT junctions formed by topological defects (i.e. pentagon-heptagon pairs). The algorithm is used to predict the tube helicities and defect configurations for bend junctions using the observed tube diameters and bend angles. The number and arrangement of the defects at the junction interfaces are found to depend on the tube helicities and bend angle. The structural and energetic calculations using the Brenner potential show a number of stable junction configurations for each bend angle with the 34 deg. bends being more stable than the others. Tight binding calculations for local density of state (LDOS) and transmission coefficients are carried out to investigate electrical properties of the bend junctions.

  5. 49 CFR 195.212 - Bending of pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field...

  6. 49 CFR 195.212 - Bending of pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field...

  7. 49 CFR 195.212 - Bending of pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field...

  8. 49 CFR 195.212 - Bending of pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field...

  9. Actuators Help Correct For Gravitational Bending Of Antenna

    NASA Technical Reports Server (NTRS)

    Levy, Roy; Strain, Douglas M.

    1996-01-01

    Force-actuator scheme devised to help correct for decrease, caused by gravitational bending, in gain of 34-m-diameter paraboloidal microwave antenna reflector used for tracking distant spacecraft and observing celestial radio sources. Also applicable to other antennas bending significantly under own weight, with consequent degradation of performance.

  10. BENDING SHOP & OVEN. United Engineering Co., Alameda, California. Plan, ...

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

    BENDING SHOP & OVEN. United Engineering Co., Alameda, California. Plan, two elevations, sections, and details. Alben Froberg, Architect, Oakland, California. Sheet no. 1 of 1. Various scales. December 15, 1941. pencil on tracing paper - United Engineering Company Shipyard, Bending Shop & Oven, 2900 Main Street, Alameda, Alameda County, CA

  11. Bend stresses arising from ion-exchange diffusion in glasses

    SciTech Connect

    Babukova, M.V.; Glebov, L.B.; Nikonorov, N.V.; Petrovskii, G.T.

    1985-11-01

    This paper demonstrates experimental confirmation of the presence of gigastresses arising under ion exchange, for the purpose of providing data relating to the magnitudes of stress greater than 1 GPa in these ion-exchange layers. To determine the stresses, a bend method was used on a specimen under nonuniform load. Small values of bend were determined on an IT-70 inferometer. With larger values of bend the radius of curvature of the surface was determined by measuring the focal distance in the beam of a He-Ne laser reflected from the specimen. Bending is observed in silicate glass subjected to unilateral ion-exchange diffusion of K/sup +/. It is shown that the bending of the specimens is caused by compressive stresses arising in the diffusion layer and having a value of greater than 1.5 GPa. The changes in the refractive index (RI) in the diffusion layer are determined primarily by the photoelastic effect.

  12. Limits of stability in supported graphene nanoribbons subject to bending

    NASA Astrophysics Data System (ADS)

    Korhonen, Topi; Koskinen, Pekka

    2016-06-01

    Graphene nanoribbons are prone to in-plane bending even when supported on flat substrates. However, the amount of bending that ribbons can stably withstand remains poorly known. Here, by using molecular dynamics simulations, we study the stability limits of 0.5-1.9-nm-wide armchair and zigzag graphene nanoribbons subject to bending. We observe that the limits for maximum stable curvatures are below ˜10 deg /nm in case the bending is externally forced and the limit is caused by buckling instability. Furthermore, it turns out that the limits for maximum stable curvatures are also below ˜10 deg /nm in case the bending is not forced and the limit arises only from the corrugated potential-energy landscape due to the substrate. Both of the stability limits lower rapidly when ribbons widen. These results agree with recent experiments and can be understood by means of transparent elasticity models.

  13. Bending properties of nickel electrodes for nickel-hydrogen batteries

    NASA Astrophysics Data System (ADS)

    Lerch, Bradley

    1995-04-01

    Recent changes in manufacturing have resulted in nickel-hydrogen batteries which fail prematurely by electrical shorting. This is believed to be a result of a blistering problem in the nickel electrodes. This study investigates the bending properties of nickel electrodes in an attempt to correlate the bending properties with the propensity of the electrode to blister. Nickel electrodes from three different batches of material were tested in both the as-received and impregnated forms. Effects of specimen curvature and position within the electrode on the bending strength were studied and within-electrode and batch-to-batch variation were addressed. Two color imaging techniques were employed which allowed differentiation of phases within the electrodes. These techniques aided in distinguishing the relative amounts of nickel hydroxide surface loading on each electrode, relating surface loading to bend strength. Bend strength was found to increase with the amount of surface loading.

  14. Bending Properties of Nickel Electrodes for Nickel-Hydrogen Batteries

    NASA Technical Reports Server (NTRS)

    Lerch, Brad A.; Wilson, Richard M.; Keller, Dennis; Corner, Ralph

    1995-01-01

    Recent changes in manufacturing have resulted in nickel-hydrogen batteries that fail prematurely by electrical shorting, This failure is believed to be a result of a blistering problem in the nickel electrodes. In this study the bending properties of nickel electrodes are investigated in an attempt to correlate the bending properties of the electrode with its propensity to blister. Nickel electrodes from three different batches of material were tested in both the as-received and impregnated forms. The effects of specimen curvature and position within the electrode on the bending strength were studied, and within-electrode and batch-to-batch variations were addressed. Two color-imaging techniques were employed to differentiate between the phases within the electrodes. These techniques aided in distinguishing the relative amounts of nickel hyroxide surface loading on each electrode, thereby relating surface loading to bend strength. Bend strength was found to increase with the amount of surface loading.

  15. Ultimate bending capacity of strain hardening steel pipes

    NASA Astrophysics Data System (ADS)

    Chen, Yan-fei; Zhang, Juan; Zhang, Hong; Li, Xin; Zhou, Jing; Cao, Jing

    2016-04-01

    Based on Hencky's total strain theory of plasticity, ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material, the simplified analytical solution is proposed as well. Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes. Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes. It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material. Thus, the ignorance of strain hardening effect, as commonly assumed in current codes, may underestimate the ultimate bending capacity of steel pipes. The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes, supports of offshore platforms and other tubular structural steel members.

  16. Electronic and optical properties of carbon nanotubes under pure bending

    NASA Astrophysics Data System (ADS)

    Koskinen, Pekka

    2010-11-01

    The high aspect ratio of carbon nanotubes makes them prone to bending. To know how bending affects the tubes is therefore crucial for tube identification and for electrical component design. Very few studies, however, have investigated tubes under small bending well below the buckling limit, because of technical problems due to broken translational symmetry. In this Brief Report a cost-effective and exact modeling of singe-walled nanotubes under such small bending is enabled by revised periodic boundary conditions, combined with density-functional tight-binding. The resulting, bending-induced changes in electronic and optical properties fall in clear chirality-dependent trend families. While the correct trends require full structural relaxation, they can be understood by one general argument. To know these trends fills a fundamental gap in our understanding of the properties of carbon nanotubes.

  17. Bending properties of nickel electrodes for nickel-hydrogen batteries

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley

    1995-01-01

    Recent changes in manufacturing have resulted in nickel-hydrogen batteries which fail prematurely by electrical shorting. This is believed to be a result of a blistering problem in the nickel electrodes. This study investigates the bending properties of nickel electrodes in an attempt to correlate the bending properties with the propensity of the electrode to blister. Nickel electrodes from three different batches of material were tested in both the as-received and impregnated forms. Effects of specimen curvature and position within the electrode on the bending strength were studied and within-electrode and batch-to-batch variation were addressed. Two color imaging techniques were employed which allowed differentiation of phases within the electrodes. These techniques aided in distinguishing the relative amounts of nickel hydroxide surface loading on each electrode, relating surface loading to bend strength. Bend strength was found to increase with the amount of surface loading.

  18. Mechanical properties of graphynes under shearing and bending

    NASA Astrophysics Data System (ADS)

    Yi, Lijun; Zhang, Yingyan; Feng, Xiqiao; Chang, Tienchong; Wang, Ji; Du, Jianke; Zhou, Jianxin

    2016-05-01

    Graphynes are the allotrope of graphene. In this work, extensive molecular dynamics simulations are performed on four different graphynes ( α - , β - , γ - , and 6,6,12-graphynes) to explore their mechanical properties (shear modulus, shear strength, and bending rigidity) under shearing and bending. While the shearing properties are anisotropic, the bending rigidity is almost independent of the chirality of graphynes. We also find that the shear modulus and shear fracture strength of graphynes decrease with increasing temperature. The effect of the percentage of the acetylenic linkages on the shear mechanical properties and bending rigidity is investigated. It is shown that the fracture shear strengths and bending rigidities of the four types of graphynes decrease, while the fracture shear strain increases, with increasing percentages of the acetylenic linkages. Significant wrinkling is observed in graphyne under shear strain. The influence of the temperatures and percentages of the acetylenic linkages on the ratio of amplitude-to-wavelength in the wrinkles are examined.

  19. R&D ERL: Magnetic measurements of the ERL magnets

    SciTech Connect

    Jain, A.

    2010-08-01

    The magnet system of ERL consists of G5 solenoids, 6Q12 quadrupoles with 0.58 T/m gradient, 3D60 dipoles with 0.4 T central field, 15 and 30 degree Z-bend injection line dipole/quadrupole combined function magnets, and extraction line magnets. More details about the magnets can be found in a report by G. Mahler. Field quality in all the 6Q12 quadrupoles, 3D60 dipoles and the injection line magnets has been measured with either a rotating coil, or a Hall probe mapper. This report presents the results of these magnetic measurements.

  20. Re-direction of dc magnetic flux in magnetically isotropic multilayered structures

    NASA Astrophysics Data System (ADS)

    Tarkhanyan, Roland H.; Niarchos, Dimitris G.

    2016-07-01

    Analytical design of a periodic composite structure allowing re-direction (bending) of dc magnetic flux with respect to applied external field is presented using methods of transformation optics. The composite structure is made of micrometer scale alternating layers of two different homogeneous and magnetically isotropic materials. Dependence of the magnetic flux bending angle on geometrical orientation of the layers as well as on the magnetic permeability ratio is examined. Such structures can find use in various devices based on the control and manipulations of the magnetic flux.

  1. Effects of magnetomechanical vibrations and bending stresses on three-phase three-leg transformers with amorphous cores

    NASA Astrophysics Data System (ADS)

    Hsu, Chang-Hung; Chang, Yeong-Hwa; Lee, Chun-Yao; Yao, Chia-Shiang; He, Yan-Lou; Chu, Huei-Lung; Chang, Chia-Wen; Chan, Wei-Shou

    2012-04-01

    This paper explores the influence of bending stresses on the magnetic characteristics of three-phase transformers with amorphous cores. Different types of core structures, including C-cores and toroidal cores, and their magnetic properties are compared using VSM and XRD. The losses in the magnetic core of the three-phase transformer are analyzed using the finite element analysis for both design and measurement. In addition, experimental results indicated that amorphous-core transformers with rectangular corners had higher audible noise and vibration intensities. This is because the condensed distribution of magnetic flux lines in the corners of the core may create high magnetic inductions associated with high magnetostriction. Finally, experiments with three-phase amorphous-core transformers were performed to study the effects of magnetism and magnetostriction on their performance in terms of core loss, vibration, and audible noise.

  2. Nonlinear bending models for beams and plates

    PubMed Central

    Antipov, Y. A.

    2014-01-01

    A new nonlinear model for large deflections of a beam is proposed. It comprises the Euler–Bernoulli boundary value problem for the deflection and a nonlinear integral condition. When bending does not alter the beam length, this condition guarantees that the deflected beam has the original length and fixes the horizontal displacement of the free end. The numerical results are in good agreement with the ones provided by the elastica model. Dynamic and two-dimensional generalizations of this nonlinear one-dimensional static model are also discussed. The model problem for an inextensible rectangular Kirchhoff plate, when one side is clamped, the opposite one is subjected to a shear force, and the others are free of moments and forces, is reduced to a singular integral equation with two fixed singularities. The singularities of the unknown function are examined, and a series-form solution is derived by the collocation method in terms of the associated Jacobi polynomials. The procedure requires solving an infinite system of linear algebraic equations for the expansion coefficients subject to the inextensibility condition. PMID:25294960

  3. ZERODUR: bending strength data for etched surfaces

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Leys, Antoine; Carré, Antoine; Kerz, Franca; Westerhoff, Thomas

    2014-07-01

    In a continuous effort since 2007 a considerable amount of new data and information has been gathered on the bending strength of the extremely low thermal expansion glass ceramic ZERODUR®. By fitting a three parameter Weibull distribution to the data it could be shown that for homogenously ground surfaces minimum breakage stresses exist lying much higher than the previously applied design limits. In order to achieve even higher allowable stress values diamond grain ground surfaces have been acid etched, a procedure widely accepted as strength increasing measure. If surfaces are etched taking off layers with thickness which are comparable to the maximum micro crack depth of the preceding grinding process they also show statistical distributions compatible with a three parameter Weibull distribution. SCHOTT has performed additional measurement series with etch solutions with variable composition testing the applicability of this distribution and the possibility to achieve further increase of the minimum breakage stress. For long term loading applications strength change with time and environmental media are important. The parameter needed for prediction calculations which is combining these influences is the stress corrosion constant. Results from the past differ significantly from each other. On the basis of new investigations better information will be provided for choosing the best value for the given application conditions.

  4. Occipital bending (Yakovlevian torque) in bipolar depression.

    PubMed

    Maller, Jerome J; Anderson, Rodney; Thomson, Richard H; Rosenfeld, Jeffrey V; Daskalakis, Zafiris J; Fitzgerald, Paul B

    2015-01-30

    Differing levels of occipital lobe asymmetry and enlarged lateral ventricles have been reported within patients with bipolar disorder (BD) compared with healthy controls, suggesting different rates of occipital bending (OB). This may exert pressure on subcortical structures, such as the hippocampus, reduced among psychiatric patients. We investigated OB prevalence in 35 patients with BD and 36 healthy controls, and ventricular and occipital volumes. Prevalence was four times higher among BD patients (12/35 [34.3%]) than in control subjects (3/36 [8.3%]), as well as larger lateral ventricular volumes (LVVs). Furthermore, we found OB to relate to left-to-right ventricular and occipital lobe volume (OLV) ratios. Those with OB also had reduced left-to-right hippocampal volume ratios. The results suggest that OB is more common among BD patients than healthy subjects, and prevalent in both BD Type I and Type II patients. We posit that anomalies in neural pruning or ventricular enlargement may precipitate OB, consequently resulting in one occipital lobe twisting around the other. Although the clinical implications of these results are unclear, the study suggests that asymmetrical ventricular volume matched with a pattern of oppositely asymmetrical occipital volume is related to OB and may be a marker of psychiatric illness. PMID:25480522

  5. Large Deformation Dynamic Bending of Composite Beams

    NASA Technical Reports Server (NTRS)

    Derian, E. J.; Hyer, M. W.

    1986-01-01

    Studies were conducted on the large deformation response of composite beams subjected to a dynamic axial load. The beams were loaded with a moderate eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied to determine potential differences between the static and dynamic failure. Twelve different laminate types were tested. The beams tested were 23 in. by 2 in. and generally 30 plies thick. The beams were loaded dynamically with a gravity-driven impactor traveling at 19.6 ft/sec and quasi-static tests were conducted on identical beams in a displacement controlled manner. For laminates of practical interest, the failure modes under static and dynamic loadings were identical. Failure in most of the laminate types occurred in a single event involving 40% to 50% of the plies. However, failure in laminates with 300 or 150 off-axis plies occurred in several events. All laminates exhibited bimodular elastic properties. The compressive flexural moduli in some laminates was measured to be 1/2 the tensile flexural modulus. No simple relationship could be found among the measured ultimate failure strains of the different laminate types. Using empirically determined flexural properties, a finite element analysis was reasonably accurate in predicting the static and dynamic deformation response.

  6. Bending analysis of laminated composite box beams

    SciTech Connect

    Tripathy, A.K.; Patel, H.J.; Pang, S.S. . Dept. of Mechanical Engineering)

    1994-01-01

    Box beams are widely used in weight reduction structures such as aircraft wings. The use of composite box beams further reduces the weight factor for such structures with the same deflection and stress as that of isotropic box beams. The difference in the behavior of composite box beam with different fiber orientation, number of plies, and number of stringers also provides a wide range of designing parameters to achieve the required performance for a given problem. A bending analysis has been carried out for the study of deflections and stresses for box beams of different material (isotropic and laminated composites), size, and number of stringers subjected to different kinds of loading conditions. A finite element model has been developed based on the strain energy principle, and the results are compared with an available commercial code COSMOS/M.'' Experiments using aluminum and scotchply composite laminates were conducted to verify the results. An optimal design for size and number of stiffeners for a given loading condition has been achieved. Investigations have also been carried out to find the effect of transverse shear on the span-wise normal stress.

  7. Atmospheric Refractive Electromagnetic Wave Bending and Propagation Delay

    NASA Astrophysics Data System (ADS)

    Mangum, Jeffrey G.; Wallace, Patrick

    2015-01-01

    In this tutorial we summarize the physics and mathematics behind refractive electromagnetic wave bending and delay. Refractive bending and delay through the Earth's atmosphere at both radio/millimetric and optical/IR wavelengths are discussed, but with most emphasis on the former, and with Atacama Large Millimeter Array (ALMA) applications in mind. As modern astronomical measurements often require subarcsecond position accuracy, care is required when selecting refractive bending and delay algorithms. For the spherically-uniform model atmospheres generally used for all refractive bending and delay algorithms, positional accuracies lsim1'' are achievable when observing at zenith angles lsim75°. A number of computationally economical approximate methods for atmospheric refractive bending and delay calculation are presented, appropriate for astronomical observations under these conditions. For observations under more realistic atmospheric conditions, for zenith angles lsim75°, or when higher positional accuracy is required, more rigorous refractive bending and delay algorithms must be employed. For accurate calculation of the refractive bending, we recommend the Auer and Standish method, using numerical integration to ray-trace through a two-layer model atmosphere, with an atmospheric model determination of the atmospheric refractivity. For the delay calculation we recommend numerical integration through a model atmosphere.

  8. Earthquakes, Segments, Bends, and Fault-Face Geology: Correlations Within the San Andreas System, California

    NASA Astrophysics Data System (ADS)

    Jachens, R. C.; Simpson, R. W.; Thurber, C. H.; Murray, J. R.

    2006-12-01

    Three-dimensional geologic maps of regions surrounding parts of the San Andreas Fault system reveal correlations between fault face geology and both short- and long-term behavior of the faults. The Loma Prieta fault segment that ruptured during the 1989 M6.9 earthquake, as defined by its aftershocks, closely corresponds to the subsurface reach (80 km long) where a large body of Logan gabbro is truncated at the fault, as defined by its magnetic anomaly. This Jurassic ophiolitic gabbro and its related rocks occupy an unusual fault-bounded basement block within Salinaa, a largely Cretaceous granitic terrane SW of the San Andreas Fault. The along-fault reach of the Logan gabbro also coincides with essentially the entire Santa Cruz Mountains left-bend in the San Andreas Fault. Rejecting a chance coincidence, the position of the Logan gabbro with respect to the left bend implies that the bend is fixed relative to Salinia and that the block NE of the San Andreas Fault has been forced to negotiate around the bend as the blocks moved past each other. Thus the basement rocks of the Logan block appear to define (control?) the Loma Prieta segment in terms both of short-term behavior (earthquakes) and long-term behavior (restraining bend fault geometry). The Parkfield segment of the San Andreas Fault also closely corresponds to a characteristic geologic unit in the NE face of the fault, the greenstone-rich Permanente terrane of the Franciscan Complex. The along-fault subsurface extent of the Permanente terrane at the fault face, as inferred from a recent 3D tomographic wavespeed model, corresponds to the reach filled by the aftershocks of the 2004 Parkfield earthquake. Furthermore, the 2004 co-seismic slip inferred from geodetic observations also coincides with the Permanente terrane at the fault face. To test whether these observations are directly related to the presence of the Permanente terrane along the fault face, we looked at fault behavior at the location of its offset

  9. Bending Electrostriction in Polyurethanes Containing Ions as Contaminants or Additives

    NASA Astrophysics Data System (ADS)

    Watanabe, Masashi; Kato, Takahiro; Suzuki, Makoto; Amaike, Yoichi; Hirai, Toshihiro

    1999-08-01

    We demonstrated that the bending electrostriction in polyurethane films is controlled by the ions contained as contaminants or additives. The sample film used in this investigation was composed of a segmented polyester-polyurethane and was coated with a thin gold electrode on each surface by ion-sputtering. Although the application of an electric field (2 MV/m) can caused bending deformation of the film, removal of the ionic contaminants from the polyurethane by electrodialysis reduced the degree of deformation. On the other hand, the addition of a small amount of lithium bromide changed the bending direction.

  10. Integration of high power lasers in bending tools

    NASA Astrophysics Data System (ADS)

    Bammer, F.; Holzinger, B.; Humenberger, G.; Schuöcker, D.; Schumi, T.

    The integration of high power lasers into bending tools creates a possibility to bend brittle materials with conventional presses. A diode laser, which is based on 200W-laser-bars and a solid state laser with 3 kW are used in this work. By heating the material within a narrow zone the ductility is increased and the forming process can be enabled. The assembly of the heat source within the bending tools is a prerequisite in order to feed energy into the workpiece before, during and after the forming process. As a result the heating and forming process can be optimized regarding any material.

  11. Damage Analysis of Rectangular Section Composite Beam under Pure Bending

    NASA Astrophysics Data System (ADS)

    Liu, Yiping; Xiao, Fan; Liu, Zejia; Tang, Liqun; Fang, Daining

    2013-02-01

    Laminated composite beams are commonly used in engineering applications involving macro to nano structures. Based on the assumption that plain sections remain plain after deformation, this paper analyzes stress distributions in cross-ply laminated composite beams with rectangular cross-sections, and formulates the basic damage equations through Kachanov's damage definition and Janson's failure criterion. The location of the neutral axis and the ultimate bending moment are obtained for pure bending cases. The effect of the elastic modulus of the two layers on the damage evolution is analyzed; a reasonable damage composite beam model is proposed to predict the ultimate bending moment.

  12. Coupled composite rotor blades under bending and torsional loads

    NASA Astrophysics Data System (ADS)

    Chandra, Ramesh; Chopra, Inderjit

    This paper presents an analytical-cum-experimental study of the structural response of composite rotor blades with elastic couplings. Vlasov theory is expanded to analyze two-cell composite rotor blades made out of general composite laminates including the transverse shear deformation of the cross-section. In order to validate this analysis, two-cell graphite-epoxy composite blades with bending-torsion coupling were fabricated using matched-die molding technique. These blades were tested under tip bending and torsional loads, and their structural response in terms of bending slope and twist was measured with a laser optical system. Good correlation between theory and experiment is achieved.

  13. Propagating director bend fluctuations in nematic liquid crystals.

    PubMed

    Humpert, Anja; Allen, Michael P

    2015-01-16

    We show, by molecular simulation, that for a range of standard, coarse-grained, nematic liquid crystal models, the director bend fluctuation is a propagating mode. This is in contrast to the generally accepted picture of nematic hydrodynamics, in which all the director modes (splay, twist, bend, and combinations thereof) are overdamped. By considering the various physical parameters that enter the equations of nematodynamics, we propose an explanation of this effect and conclude that propagating bend fluctuations may be observable in some experimental systems. PMID:25635566

  14. Optimum design of ninety degree bends

    NASA Technical Reports Server (NTRS)

    Modi, Vijay; Cabuk, Hayri; Huan, Jian-Chun; Quadracci, Richard

    1992-01-01

    An algorithm for the optimum design of an internal flow component to obtain the maximum pressure rise is presented. Maximum pressure rise in a duct with simultaneous turning and diffusion is shown to be related to the control of flow separation on the passage walls. Such a flow is usually associated with downstream conditions that are desirable in turbomachinery and propulsion applications to ensure low loss and stable performance. The algorithm requires the solution of an 'adjoint' problem in addition to the 'direct' equations governing the flow in a body, which in the present analysis are assumed to be the laminar Navier-Stokes equations. The theoretical framework and computational algorithms presented in this study are for the steady Navier-Stokes equations. A procedure is developed for the numerical solution of the adjoint equations. This procedure is coupled with a direct solver in a design iteration loop, that provides a new shape with a higher pressure rise. This procedure is first validated for the design of optimum plane diffusers in two-dimensional flow. The direct Navier-Stokes and the 'adjoint' equations are solved using a finite volume formulation for spatial discretization in an artificial compressibility framework. A simplified version of the above approach is then utilized to design ninety degree diffusing bends. Calculations were carried out for a mean radius ratio at inlet of 2.5 and Reynolds numbers varying from 100 to 500. While at this stage laminar flows is assumed, it is shown that a similar approach can be conceived for turbulent flows.

  15. Advantages of customer/supplier involvement in the upgrade of River Bend`s IST program

    SciTech Connect

    Womack, R.L.; Addison, J.A.

    1996-12-01

    At River Bend Station, IST testing had problems. Operations could not perform the test with the required repeatability; engineering could not reliably trend test data to detect degradation; licensing was heavily burdened with regulatory concerns; and maintenance could not do preventative maintenance because of poor prediction of system health status. Using Energy`s Total Quality principles, it was determined that the causes were: lack of ownership, inadequate test equipment usage, lack of adequate procedures, and lack of program maintenance. After identifying the customers and suppliers of the IST program data, Energy management put together an upgrade team to address these concerns. These customers and suppliers made up the IST upgrade team. The team`s mission was to supply River Bend with a reliable, functional, industry correct and user friendly IST program. The IST program in place went through a verification process that identified and corrected over 400 individual program discrepancies. Over 200 components were identified for improved testing methods. An IST basis document was developed. The operations department was trained on ASME Section XI testing. All IST tests have been simplified and shortened, due to heavy involvement by operations in the procedure development process. This significantly reduced testing time, resulting in lower cost, less dose and greater system availability.

  16. Turbulent flow computation in a circular U-Bend

    NASA Astrophysics Data System (ADS)

    Miloud, Abdelkrim; Aounallah, Mohammed; Belkadi, Mustapha; Adjlout, Lahouari; Imine, Omar; Imine, Bachir

    2014-03-01

    Turbulent flows through a circular 180° curved bend with a curvature ratio of 3.375, defined as the the bend mean radius to pipe diameter is investigated numerically for a Reynolds number of 4.45×104. The computation is performed for a U-Bend with full long pipes at the entrance and at the exit. The commercial ANSYS FLUENT is used to solve the steady Reynolds-Averaged Navier-Stokes (RANS) equations. The performances of standard k-ɛ and the second moment closure RSM models are evaluated by comparing their numerical results against experimental data and testing their capabilities to capture the formation and extend this turbulence driven vortex. It is found that the secondary flows occur in the cross-stream half-plane of such configurations and primarily induced by high anisotropy of the cross-stream turbulent normal stresses near the outer bend.

  17. DESIGN MANUAL: SWIRL AND HELICAL BEND POLLUTION CONTROL DEVICES

    EPA Science Inventory

    This design manual contains descriptions of design procedures and operating experience to date, including results obtained, for secondary flow pollution control devices. Two types of combined sewer overflow regulators are described: the swirl and the helical bend regulator/separa...

  18. Technique cuts time and cost of bending jacketed piping

    NASA Technical Reports Server (NTRS)

    Gardner, J. N.

    1967-01-01

    Technique uses a stiff medium in the annular space between inner and outer pipes of jacketed piping in transfer lines. The process eliminates splitting and welding and makes possible the use of standard pipe-bending tools.

  19. Thickness-dependent bending modulus of hexagonal boron nitride nanosheets

    NASA Astrophysics Data System (ADS)

    Li, Chun; Bando, Yoshio; Zhi, Chunyi; Huang, Yang; Golberg, Dmitri

    2009-09-01

    Bending modulus of exfoliation-made single-crystalline hexagonal boron nitride nanosheets (BNNSs) with thicknesses of 25-300 nm and sizes of 1.2-3.0 µm were measured using three-point bending tests in an atomic force microscope. BNNSs suspended on an SiO2 trench were clamped by a metal film via microfabrication based on electron beam lithography. Calculated by the plate theory of a doubly clamped plate under a concentrated load, the bending modulus of BNNSs was found to increase with the decrease of sheet thickness and approach the theoretical C33 value of a hexagonal BN single crystal in thinner sheets (thickness<50 nm). The thickness-dependent bending modulus was suggested to be due to the layer distribution of stacking faults which were also thought to be responsible for the layer-by-layer BNNS exfoliation.

  20. Active vibration control of structures undergoing bending vibrations

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

    1995-01-01

    An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

  1. GENERAL VIEW ROUTE OF BEND FEED CANAL FLUME #4 REPLACEMENT ...

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

    GENERAL VIEW ROUTE OF BEND FEED CANAL FLUME #4 REPLACEMENT SIPHON FROM WEST BANK TUMALO CREEK. LOOKING EAST - Tumalo Irrigation District, Tumalo Project, West of Deschutes River, Tumalo, Deschutes County, OR

  2. VIEW OF BEND FEED CANAL FLUME #4 REPLACEMENT SIPHON OUTLET ...

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

    VIEW OF BEND FEED CANAL FLUME #4 REPLACEMENT SIPHON OUTLET STRUCTURE ON WEST BANK OF TUMALO CREEK. LOOKING EAST - Tumalo Irrigation District, Tumalo Project, West of Deschutes River, Tumalo, Deschutes County, OR

  3. VIEW OF NORTHWEST BEND IN BIRCH CIRCLE. VIEW FACING WEST ...

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

    VIEW OF NORTHWEST BEND IN BIRCH CIRCLE. VIEW FACING WEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  4. POU proteins bend DNA via the POU-specific domain.

    PubMed Central

    Verrijzer, C P; van Oosterhout, J A; van Weperen, W W; van der Vliet, P C

    1991-01-01

    POU proteins constitute a family of ubiquitous as well as cell type-specific transcription factors that share the conserved POU DNA binding domain. This domain consists of two distinct subdomains, a POU-specific domain and a POU homeodomain, that are both required for high affinity sequence-specific DNA binding. In a circular permutation assay, several POU proteins, including Oct-1, Oct-2A, Oct-6 and Pit-1, demonstrated a position dependent mobility of the protein-DNA complexes, suggesting induction of DNA bending. This was confirmed by detection of relative bend direction, using pre-bent DNA, and by enhanced ligase mediated cyclization. Bending was caused by interaction with the POU domain. By contrast, binding of the POU homeodomain did not distort the DNA structure, indicating that the POU-specific domain confers DNA bending. Images PMID:1915275

  5. Bending Properties of Nickel Electrodes for Nickel-Hydrogen Batteries

    NASA Technical Reports Server (NTRS)

    Lerch, Brad A.; Wilson, Richard M.; Keller, Dennis; Corner, Ralph

    1996-01-01

    Recent changes in manufacturing have resulted in nickel-hydrogen batteries that fail prematurely by electrical shorting. This failure is believed to be a result of a blistering problem in the nickel electrodes. In this study, the bending properties of nickel electrodes are investigated in an attempt to correlate the bending properties of the electrode with its propensity to blister. Nickel electrodes from three different batches of material were tested in both the as-received and impregnated forms. The effects of specimen curvature and position within the electrode on the bending strength were studied, and within-electrode and batch-to-batch variations were addressed. Bend strength was found to increase with the amount of surface loading.

  6. 9. NORTH SIDE, FROM A BOAT. THE TWO BENDING SHOP ...

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

    9. NORTH SIDE, FROM A BOAT. THE TWO BENDING SHOP AND OVEN BUILDINGS ARE VISIBLE AT THE RIGHT. - United Engineering Company Shipyard, Engineering Building, 2900 Main Street, Alameda, Alameda County, CA

  7. Theory of bending waves with applications to disk galaxies

    SciTech Connect

    Mark, J.W.K.

    1982-01-01

    A theory of bending waves is surveyed which provides an explanation for the required amplification of the warp in the Milky Way. It also provides for self-generated warps in isolated external galaxies. The shape of observed warps and partly their existence in isolated galaxies are indicative of substantial spheroidal components. The theory also provides a plausible explanation for the bending of the inner disk (<2 kpc) of the Milky Way.

  8. Calibration of combined bending-torsion fatigue reliability data reduction

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Mcconnell, J. B.

    1969-01-01

    The combined bending-torsion fatigue reliability research machines are described. Three such machines are presently in operation. The calibration of these machines is presented in depth. Fatigue data generated with these machines for SAE 4340 steel grooved specimens subjected to reversed bending and steady torque loading are given. The data reduction procedure is presented. Finally, some comments are made about notch sensitivity and stress concentration as applied to combined fatigue.

  9. Bending strength studies on hot-pressed silicon carbide

    NASA Technical Reports Server (NTRS)

    Kriegesmann, J.

    1984-01-01

    The 4-point bending strength of 4 grades of hot-pressed SiC was determined at different temperatures. With a transgranular mode of fracture the values for bending strength are retained up to high temperatures. For intergranular fracture the decrease of strength is governed by subcritical crack growth. The intergranular fracture is caused by a high content of silicate glassy phase at the grain boundaries of hot-pressed SiC.

  10. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    A study of the attenuation of bending boundary layers in balanced and unbalanced, symmetrically and unsymmetrically laminated cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize the effects of laminate orthotropy and anisotropy on the bending boundary-layer decay length in a very general manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all laminates considered, the results show that the differences between results obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that, in some cases, neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and, in other cases, results in an overestimation.

  11. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    An analytical, parametric study of the attenuation of bending boundary layers or edge effects in balanced and unbalanced, symmetrically and unsymmetrically laminated thin cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize and quantify the effects of laminate orthotropy and laminate anisotropy on the bending boundary-layer decay length in a very general and encompassing manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all the laminate constructions considered, the results show that the differences between results that were obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that in some cases neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and in other cases it results in an overestimation.

  12. Bending of Light in Modified Gravity at Large Distances

    NASA Technical Reports Server (NTRS)

    Sultana, Joseph; Kazanas, Demosthenes

    2012-01-01

    We discuss the bending of light in a recent model for gravity at large distances containing a Rindler type acceleration proposed by Grumiller. We consider the static, spherically symmetric metric with cosmological constant and Rindler-like term 2ar presented in this model, and we use the procedure by Rindler and Ishak. to obtain the bending angle of light in this metric. Earlier work on light bending in this model by Carloni, Grumiller, and Preis, using the method normally employed for asymptotically flat space-times, led to a conflicting result (caused by the Rindler-like term in the metric) of a bending angle that increases with the distance of closest approach r(sub 0) of the light ray from the centrally concentrated spherically symmetric matter distribution. However, when using the alternative approach for light bending in nonasymptotically flat space-times, we show that the linear Rindler-like term produces a small correction to the general relativistic result that is inversely proportional to r(sub 0). This will in turn affect the bounds on Rindler acceleration obtained earlier from light bending and casts doubts on the nature of the linear term 2ar in the metric

  13. First cell magnet system tests

    SciTech Connect

    Schneider, W.J.; Brown, D.P.; Briggs, J.J.; Foerster, C.L.; Halama, H.J.; Schlafke, A.P.; Werner, A.P.

    1981-01-01

    The ISABELLE refrigeration system utilizes compressed liquid helium to supply refrigeration to nearly 1100 superconducting bending and focusing magnets. These magnets steer the proton orbits of the accelerator and are arranged into two interlocking rings. The total heat load that the refrigerator must provide is made up of the heat load of the magnets, magnet leads and vessels and the interconnecting piping to the refrigerator. The design and test results of the magnet system during various operating conditions in use on the ISABELLE prototype, the First Cell, are described.

  14. Superconducting energy storage magnet

    NASA Technical Reports Server (NTRS)

    Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

    1993-01-01

    A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

  15. Nonlinear Curvature Expressions for Combined Flapwise Bending, Chordwise Bending, Torsion and Extension of Twisted Rotor Blades

    NASA Technical Reports Server (NTRS)

    Kvaternik, R. G.; Kaza, K. R. V.

    1976-01-01

    The nonlinear curvature expressions for a twisted rotor blade or a beam undergoing transverse bending in two planes, torsion, and extension were developed. The curvature expressions were obtained using simple geometric considerations. The expressions were first developed in a general manner using the geometrical nonlinear theory of elasticity. These general nonlinear expressions were then systematically reduced to four levels of approximation by imposing various simplifying assumptions, and in each of these levels the second degree nonlinear expressions were given. The assumptions were carefully stated and their implications with respect to the nonlinear theory of elasticity as applied to beams were pointed out. The transformation matrices between the deformed and undeformed blade-fixed coordinates, which were needed in the development of the curvature expressions, were also given for three of the levels of approximation. The present curvature expressions and transformation matrices were compared with corresponding expressions existing in the literature.

  16. Coupled bending-bending-torsion flutter of a mistuned cascade with nonuniform blades

    NASA Technical Reports Server (NTRS)

    Kaza, K. R. V.; Kielb, R. E.

    1982-01-01

    A set of aeroelastic equations describing the motion of an arbitrarily mistuned cascade with flexible, pretwisted, nonuniform blades is developed using an extended Hamilton's principle. The derivation of the equations has its basis in the geometric nonlinear theory of elasticity in which the elongations and shears are negligible compared to unity. A general expression for foreshortening of a blade is derived and is explicity used in the formulation. The blade aerodynamic loading in the subsonic and supersonic flow regimes is obtained from two dimensional, unsteady, cascade theories. The aerodynamic, inertial and structural coupling between the bending (in two planes) and torsional motions of the blade is included. The equations are used to investigate the aeroelastic stability and to quantify the effect of frequency mistuning on flutter in turbofans. Results indicate that a moderate amount of intentional mistuning has enough potential to alleviate flutter problems in unshrouded, high aspect ratio turbofans.

  17. Analyses of MHD Pressure Drop in a Curved Bend for Different Liquid Metals

    NASA Astrophysics Data System (ADS)

    Arshad, Kameel; Rafique, Muhammad; Majid, Asad

    In this research we have analyzed liquid-metal flow in a curved bend in the presence of a magnetic field, which acts in two transverse directions. The magnetic field along the x-axis varied as B0(R + x)-1, while the magnetic field in y-direction is kept constant. The duct has conducting vanadium walls and liquid metal (lithium, sodium and potassium) have been used as a coolant. Magneto hydrodynamic (MHD) equations in three dimensions have been developed in the modified toroidal coordinate system. Then these coupled set of equations are solved by using finite difference techniques and an extended SIMPLER algorithm approach and an estimation of MHD pressure drop has been made for three different liquid metals, namely lithium, sodium and potassium. The results for a curved bend indicate an immense axial MHD pressure drop. The axial MHD pressure drop for three liquid metals, increases for an increase in both kinds of magnetic fields. It has been found that the MHD pressure drop is maximum in the case of sodium and minimum in the case of lithium In this paper a detailed comparative analysis has been carried out to find a suitable fluid for the cooling of high heat flux components of a fusion reactor, which is compatible with liquid metal lithium blanket and can also remove the 5 MW m-2 heat flux falling on the limiter or diverter plate. We finally concluded that from MHD pressure drop point of view that liquid lithium is the best choice for cooling of high heat flux components of a fusion reactor

  18. Refrigeration options for the Advanced Light Source Superbend Dipole Magnets

    SciTech Connect

    Green, M.A.; Hoyer, E.H.; Schlueter, R.D.; Taylor, C.E.; Zbasnik, J.; Wang, S.T.

    1999-07-09

    The 1.9 GeV Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL) produces photons with a critical energy of about 3.1 kev at each of its thirty-six 1.3 T gradient bending magnets. It is proposed that at three locations around the ring the conventional gradient bending magnets be replaced with superconducting bending magnets with a maximum field of 5.6 T. At the point where the photons are extracted, their critical energy will be about 12 keV. In the beam lines where the SuperBend superconducting magnets are installed, the X ray brightness at 20 keV will be increased over two orders of magnitude. This report describes three different refrigeration options for cooling the three SuperBend dipoles. The cooling options include: (1) liquid helium and liquid nitrogen cryogen cooling using stored liquids, (2) a central helium refrigerator (capacity 70 to 100 W) cooling all of the SuperBend magnets, (3) a Gifford McMahon (GM) cryocooler on each of the dipoles. This paper describes the technical and economic reasons for selecting a small GM cryocooler as the method for cooling the SuperBend dipoles on the LBNL Advanced Light Source.

  19. [Relationship between hardness, abrasion and bending strength of UV-polymerizable adhesives].

    PubMed

    Reinhardt, K J; Vahl, J

    1978-04-01

    These experiments were undertaken to explore the influence of hardening on bending and bending strength of photopolymerisable adhesives. It was shown that light sources at present in use only influence the bending strength to a small degree but enable 40% variation in bending. The use of more intensive light sources not yet in commercial use led to further improvements. PMID:274282

  20. Nondestructive Detection of Flaw in Carbon-Fiber-Reinforced Plastics Using High-\\mbi{T}\\textbf{c} Superconducting Quantum Interference Device

    NASA Astrophysics Data System (ADS)

    Kasai, Naoko; Suzuki, Daisuke; Hatsukade, Yoshimi; Koyanagi, Masao

    2000-03-01

    The nondestructive detection of small cracks and deep-lying flaws in structures is important for safety inspection. Carbon-fiber-reinforced plastics (CFRP) are complex materials for use in aircrafts and structures. We investigated the possibility of detecting flaws in CFRP using a nondestructive evaluation system using high-Tc superconducting quantum interference device (SQUID). A SQUID system for the nondestructive evaluation was developed using a SQUID magnetometer and a SQUID gradiometer fabricated based on a YBa2Cu3O7-δ thin film. Holes, the diameters of which were equal to or larger than 0.4 mm, were made in CFRP plates and all holes except the smallest one were detected by a current-injection method using this system. The results show that the location and the diameter of the holes can be estimated from the distribution of the magnetic flux density, Bz, measured by the magnetometer or the distribution of the first-order gradient of Bz, dBz/dx, measured by the gradiometer. The effect of texture of the carbon fiber in CFRP on the magnetic signal strength was discussed.

  1. Uncoupled achromatic tilted S-bend

    SciTech Connect

    Tsoupas,N.; Kayran, D.; Litvinenko, V.; MacKay, W.W.

    2008-06-23

    A particular section of the electron beam transport line, to be used in the e-cooling project [l] of the Relativistic Heavy Ion Collider (RHIC), is constrained to displace the trajectory with both horizontal and vertical offsets so that the outgoing beamline is parallel to the incoming beamline. We also require that section be achromatic in both planes. This mixed horizontal and vertical achromatic Sbend is accomplished by rotating the two dipoles and the quadrupoles of the line, about the longitudinal axis of the incoming beam. However such a rotation of the magnetic elements may couple the transported beam through the first order beam transfer matrix (linear coupling). In this paper we study a sufficient condition, that the first order transport matrix (R-matrix) can satisfy, so that this section of beam transfer line is both achromatic and linearly uncoupled. We provide a complete solution for the beam optics which satisfies both conditions.

  2. How do spin waves pass through a bend?

    PubMed Central

    Xing, Xiangjun; Yu, Yongli; Li, Shuwei; Huang, Xiaohong

    2013-01-01

    Spin-wave devices hold great promise to be used in future information processing. Manipulation of spin-wave propagation inside the submicrometer waveguides is at the core of promoting the practical application of these devices. Just as in today's silicon-based chips, bending of the building blocks cannot be avoided in real spin-wave circuits. Here, we examine spin-wave transport in bended magnonic waveguides at the submicron scale using micromagnetic simulations. It is seen that the impact of the bend is relevant to the frequency of the passing spin wave. At the lowest frequencies, the spin wave continuously follows the waveguide in the propagation process. At the higher frequencies, however the bend acts as a mode converter for the passing spin wave, causing zigzag-like propagation path formed in the waveguide behind the bend. Additionally, we demonstrate a logic-NOT gate based on such a waveguide, which could be combined to perform logic-NAND operation. PMID:24129823

  3. Bending-induced phase transition in monolayer black phosphorus

    NASA Astrophysics Data System (ADS)

    Pan, Dou-Xing; Wang, Tzu-Chiang; Guo, Wan-Lin

    2015-08-01

    Bending-induced phase transition in monolayer black phosphorus is investigated through first principles calculations. By wrapping the layer into nanotubes along armchair and zigzag directions with different curvatures, it is found that phase transitions of the tubes occur when radius of curvature is smaller than 5 Å in bending along the zigzag direction, while the tubes remain stable along the armchair direction. Small zigzag tubes with odd numbered monolayer unit cells tend to transfer toward armchair-like phases, but the tubes with even numbered monolayer unit cells transfer into new complex bonding structures. The mechanism for the bending-induced phase transition is revealed by the comprehensive analyses of the bending strain energies, electron density distributions, and band structures. The results show significant anisotropic bending stability of black phosphorus and should be helpful for its mechanical cleavage fabrication in large size. Project supported by the National Natural Science Foundation of China (Grant Nos. 11021262, 11172303, and 11132011) and the National Basic Research Program of China (Grant No.2012CB937500).

  4. Performance evaluation of bending actuators made from electrostrictive graft elastomers

    NASA Astrophysics Data System (ADS)

    Su, Ji; Costen, Robert C.; Harrison, Joycelyn S.; Newbury, Kenneth M.; Leo, Donald J.

    2002-07-01

    Recently a new class of electrostrictive polymers, called electrostrictive graft elastomers, was developed at NASA Langley Research Center. In this work, the output force of a bending actuator made from electrostrictive graft elastomer was measured and modeled to understand the dependence of performance on device configuration. This understanding should lead to better actuator design and fabrication. The prototype bending actuator is 47micrometers thick and 8 mm wide. The output bending force at the tip was measured as a function of applied voltage and the distance from the tip to the holding stage. The output force at 2.1 kV increases from 124(mu) N at a length of 33.5 mm to 662(mu) N at 7 mm. Accourding to a small displacement, 5-layer, a strength-of- materials model, the output bending force of the actuator varies inversely with its length and directly with the square of the applied voltage. Consequently, the output bending force can be about 5 mN when the length of the actuator is reduced to 1 mm for application to micro- electromechanical (MEMS) devices. The experimental results will be presented and a method for enhancing the performance will also be discussed.

  5. Theoretical and experimental investigation of magnetoelectric effect for bending-tension coupled modes in magnetostrictive-piezoelectric layered composites

    NASA Astrophysics Data System (ADS)

    Hasanyan, D.; Gao, J.; Wang, Y.; Viswan, R.; Li, M.; Shen, Y.; Li, J.; Viehland, D.

    2012-07-01

    In this paper, we discuss a theoretical model with experimental verification for the resonance enhancement of magnetoelectric (ME) interactions at frequencies corresponding to bending-tension oscillations. A dynamic theory of arbitrary laminated magneto-elasto-electric bars was constructed. The model included bending and longitudinal vibration effects for predicting ME coefficients in laminate bar composite structures consisting of magnetostrictive, piezoelectric, and pure elastic layers. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account, as such the bending deformations should be considered in an applied magnetic or electric field. The frequency dependence of the ME voltage coefficients has obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to free vibrations at both ends. As a demonstration, our theory for multilayer ME composites was then applied to ferromagnetic-ferroelectric bilayers, specifically Metglas-PZT ones. A theoretical model is presented for static (low-frequency) ME effects in such bilayers. We also performed experiments for these Metglas-PZT bilayers and analyzed the influence of Metglas geometry (length and thickness) and Metglas/PZT volume fraction on the ME coefficient. The frequency dependence of the ME coefficient is also presented for different geometries (length, thickness) of Metglas. The theory shows good agreement with experimental data, even near the resonance frequency.

  6. Effect of bend separation distance on the mass transfer in back-to-back pipe bends arranged in a 180° configuration

    NASA Astrophysics Data System (ADS)

    Chen, X.; Le, T.; Ewing, D.; Ching, C. Y.

    2016-02-01

    The mass transfer to turbulent flow through back-to-back pipe bends arranged in a 180° configuration with different lengths of pipe between the bends was measured using a dissolving gypsum test section in water. The measurements were performed for bends with a radius of curvature of 1.5 times the pipe diameter (D) at a Reynolds numbers of 70,000 and Schmidt number of 1280. The maximum mass transfer in the bends decreased from approximately 1.8 times the mass transfer in the upstream pipe when there was no separation distance between the bends to 1.7 times when there was a 1D or 5D length of pipe between the bends. The location of the maximum mass transfer was on the inner sidewall downstream of the second bend when there was no separation distance between the bends. This location changed to the inner wall at the beginning of the second bend when there was a 1D long pipe between the bends, and to the inner sidewall at the end of the first bend when there was a 5D long pipe between the bends.

  7. Contact and Bending Durability Calculation for Spiral-Bevel Gears

    NASA Technical Reports Server (NTRS)

    Vijayakar, Sandeep

    2016-01-01

    The objective of this project is to extend the capabilities of the gear contact analysis solver Calyx, and associated packages Transmission3D, HypoidFaceMilled, HypoidFaceHobbed. A calculation process for the surface durability was implemented using the Dowson-Higginson correlation for fluid film thickness. Comparisons to failure data from NASA's Spiral Bevel Gear Fatigue rig were carried out. A bending fatigue calculation has been implemented that allows the use of the stress-life calculation at each individual fillet point. The gears in the NASA test rig did not exhibit any bending fatigue failure, so the bending fatigue calculations are presented in this report by using significantly lowered strength numbers.

  8. Simulated Single Tooth Bending of High Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert, F.; Burke, Christopher

    2012-01-01

    Future unmanned space missions will require mechanisms to operate at extreme conditions in order to be successful. In some of these mechanisms, very high gear reductions will be needed to permit very small motors to drive other components at low rotational speed with high output torque. Therefore gearing components are required that can meet the mission requirements. In mechanisms such as this, bending fatigue strength capacity of the gears is very important. The bending fatigue capacity of a high temperature, nickel-based alloy, typically used for turbine disks in gas turbine engines and two tool steel materials with high vanadium content, were compared to that of a typical aerospace alloy-AISI 9310. Test specimens were fabricated by electro-discharge machining without post machining processing. Tests were run at 24 and at 490 C. As test temperature increased from 24 to 490 C the bending fatigue strength was reduced by a factor of five.

  9. Stretching and bending in cross-linked biopolymer networks

    NASA Astrophysics Data System (ADS)

    Heussinger, Claus; Frey, Erwin

    2007-03-01

    The elastic response of cross-linked biopolymer networks is usually interpreted in terms of affine stretching models, adopted from the theory of rubber-elasticity valid for flexible polymer gels. Unlike flexible polymers, however, stiff polymers have a highly anisotropic elastic response, where the low-energy elastic excitations are actually of bending nature. As a consequence, similar to springs connected in series, one would expect the softer bending mode to dominate the elastic energy rather than the stiff stretching mode. We propose a theory that, unlike recent affine models, properly accounts for the soft bending response of stiff polymers. It allows calculating the macroscopic elastic moduli starting from a microscopic characterization of the (non-affine) deformation field. The calculated scaling properties for the shear modulus are in excellent agreement with the results of recent simulations obtained in simple two-dimensional model networks, and can also be applied to rationalize bulk rheological data in reconstituted actin networks.

  10. Flood characteristics of the Buffalo River at Tyler Bend, Arkansas

    USGS Publications Warehouse

    Neely, Braxtel L.

    1987-01-01

    The Buffalo River is located in the Ozark Mountains in north-central Arkansas. Tyler Bend is on the Buffalo River about 1.5 miles upstream from U.S. Highway 65. The National Park Service is developing several recreational park sites along this scenic river. The magnitude, frequency, duration and velocities of floods are primary factors needed for establishing guidelines for developing facilities and managing park sites. The Park Service plans to develop park facilities at Tyler Bend and needs flood information at this site. This report provides information on the 100-, 75-, 50-, 30-, 20-, 10-, and 5-year floods on the Buffalo River at Tyler Bend. It was prepared by the U.S. Geological Survey in cooperation with the National Park Service and is based on data collected during the December 1982 flood, gaging station data for the Buffalo River near St. Joe, Arkansas and a Statewide flood-frequency report. (Lantz-PTT)

  11. Estimation of blade airloads from rotor blade bending moments

    NASA Technical Reports Server (NTRS)

    Bousman, William G.

    1987-01-01

    A method is developed to estimate the blade normal airloads by using measured flap bending moments; that is, the rotor blade is used as a force balance. The blade's rotation is calculated in vacuum modes and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated for measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.

  12. Modeling of bend effects on fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Cadusch, Peter J.; Thompson, Alexander C.; Stoddart, Paul R.; Wade, Scott A.

    2012-02-01

    Sensing and telecommunication applications requiring the bending of optical fibers to small diameters are on the increase. Recent work has shown that the centre wavelength of fiber Bragg gratings has a bend dependence the magnitude of which varies with the type of fiber in which the grating is written. In this work the basis of the centre wavelength shift is investigated by modeling the effects of several potential causes for standard and depressed cladding fiber designs. The majority of the expected affects, including bend induced stress and mode field deformation, were found to result in small wavelength shifts in the opposite direction to those observed experimentally. However, a new account of the shift, based on simplistic geometrical optics, does show wavelength changes in the observed direction, of up to -0.15 nm, which is in the range of the experimentally measured shifts.

  13. Flow resistance of ice slurry in bends and elbow pipes

    NASA Astrophysics Data System (ADS)

    Niezgoda-Żelasko, B.; Żelasko, J.

    2014-08-01

    The present paper covers the flow of ice slurry made of a 10.6% ethanol solution through small-radius bends and elbow pipes. The paper presents the results of experimental research on the flow resistances of Bingham-fluid ice slurry in bends and elbows. The research, performed for three pipe diameters and a relative bend radius of 1<=D/di<=2, has made it possible to take into consideration the influence of friction resistances as well the of the flow geometry on the total local resistance coefficients. The study attempts to make the local resistance coefficient dependent on the Dean number defined for a generalized Reynolds number according to Metzner-Reade

  14. Longitudinal-bending mode micromotor using multilayer piezoelectric actuator.

    PubMed

    Yao, K; Koc, B; Uchino, K

    2001-07-01

    Longitudinal-bending mode ultrasonic motors with a diameter of 3 mm were fabricated using stacked multilayer piezoelectric actuators, which were self-developed from hard lead zirconate titanate (PZT) ceramic. A bending vibration was converted from a longitudinal vibration with a longitudinal-bending coupler. The motors could be bidirectionally operated by changing driving frequency. Their starting and braking torque were analyzed based on the transient velocity response. With a load of moment of inertia 2.5 x 10(-7) kgm2, the motor showed a maximum starting torque of 127.5 microNm. The braking torque proved to be a constant independent on the motor's driving conditions and was roughly equivalent to the maximum starting torque achievable with our micromotors. PMID:11477764

  15. Strain localization and damage development in 2060 alloy during bending

    NASA Astrophysics Data System (ADS)

    Jin, Xiao; Fu, Bao-qin; Zhang, Cheng-lu; Liu, Wei

    2015-12-01

    The microstructure evolution and damage development of the third-generation Al-Li alloy 2060 (T8) were studied using in situ bending tests. Specimens were loaded with a series of punches of different radii, and the microstructure evolution was studied by scanning electron microscopy, electron backscatter diffraction, and digital image correlation (DIC) methods. The evolution of the microscopic fracture strain distribution and microstructure in 2060 alloy during bending was characterized, where the dispersion distribution of precipitates was recorded by backscattered electron imaging and later inputted into a DIC system for strain calculations. The experimental results showed that strain localization in the free surface of bent specimens induced damage to the microstructure. The region of crack initiation lies on the free surface with maximum strain, and the shear crack propagates along the macro-shear band in the early stages of bending. Crack propagation in the later stages was interpreted on the basis of the conventional mechanism of ductile fracture.

  16. Bending properties of foamed aluminum panels and sandwiches

    SciTech Connect

    Simancik, F.; Kovacik, J.; Minarikova, N.

    1998-12-31

    The foamed panels and sandwiches were prepared by powder metallurgical route using various matrix alloys. The effect of the apparent density, geometry and structure of the foam on its bending stiffness was studied with respect to the results of the four-point-bending. It has been shown that the modulus of elasticity of the foam cannot be related only to its apparent density, because the distribution of the cell-wall material along the thickness of the foamed panel is not uniform. Therefore the real moment of inertia of the foam`s cross-section should be used for the calculation of bending stiffness. This moment can be determined from the square weight of the foamed sample.

  17. Platonic Scattering Cancellation for Bending Waves in a Thin Plate

    PubMed Central

    Farhat, M.; Chen, P.-Y.; Bağcı, H.; Enoch, S.; Guenneau, S.; Alù, A.

    2014-01-01

    We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry. PMID:24844801

  18. [Effect of bending on shot peened and polished osteosynthesis plates].

    PubMed

    Starker, M; Fröhling, M; Hirsch, T

    1991-03-01

    Shot peening can increase the fatigue strength of commercially available surgical plates made of 1.4435 alloy by 40% even in a corrosive environment. Our investigations show that residual stresses resulting from shot peening are reduced by additional bending of the plates. In such plates smaller tensile residual stresses were found than after polishing of the plates. Bending of polished plates results in considerable tensile residual stresses. The hardening achieved by shot peening is not reduced by bending. As the fatigue strength of soft materials depends mainly on the hardening and less on the residual stresses, only little influence of the changed residual stresses on the fatigue strength can be expected. Shot peening of surgical implants thus means an improvement in quality. PMID:2054460

  19. Ultrathin 90-degree sharp bends for spoof surface plasmon polaritons.

    PubMed

    Yang, Yihao; Chen, Hongsheng; Xiao, Sanshui; Mortensen, N Asger; Zhang, Jingjing

    2015-07-27

    At low frequencies outside the plasmonic range, strongly confined surface waves can be achieved on periodically structured metal surfaces, thereby allowing for the design of compact electromagnetic guiding devices. Here, we propose an approach to realize highly efficient transmission of spoof surface plasmons around 90-degree sharp bends on ultrathin metallic films in the microwave regime. We demonstrate that by judiciously engineering the structure, the dispersion relation can be designed to reduce the scattering. Furthermore, the reflection can be suppressed by proper structural decoration at the bending corner. A one-dimensional scattering theory is employed to understand and verify the transmission properties of our waveguide bend structure. Our design scheme is not restricted to the specific structure we propose here but can be applied to other guiding components built up on two dimensional metal surfaces. PMID:26367570

  20. Single crystal plasticity with bend-twist modes

    NASA Astrophysics Data System (ADS)

    Elkhodary, Khalil I.; Bakr, Mohamed A.

    2015-06-01

    In this work a formulation is proposed and computationally implemented for rate dependent single crystal plasticity, which incorporates plastic bend-twist modes that arise from dislocation density based poly-slip mechanisms. The formulation makes use of higher order continuum theory and may be viewed as a generalized micromechanics model. The formulation is then linked to the burgers and Nye tensors, showing how their material rates are derivable from a newly proposed third-rank tensor Λp, which incorporates a crystallographic description of bend-twist plasticity through selectable slip-system level constitutive laws. A simple three-dimensional explicit finite element implementation is outlined and employed in three simulations: (a) bi-crystal bending; (b) tension on a notched single crystal; and (c) the large compression of a microstructure to induce the plastic buckling of secondary phases. All simulation are transient, for computational expediency. The results shed light on the physics resulting from dynamic inhomogeneous plastic deformation.

  1. Platonic Scattering Cancellation for Bending Waves in a Thin Plate

    NASA Astrophysics Data System (ADS)

    Farhat, M.; Chen, P.-Y.; Bağcı, H.; Enoch, S.; Guenneau, S.; Alù, A.

    2014-04-01

    We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry.

  2. Bending of light in modified gravity at large distances

    NASA Astrophysics Data System (ADS)

    Sultana, Joseph; Kazanas, Demosthenes

    2012-04-01

    We discuss the bending of light in a recent model for gravity at large distances containing a Rindler-type acceleration proposed by Grumiller [Phys. Rev. Lett. 105, 211303 (2010)10.1103/PhysRevLett.105.211303PRLTAO0031-9007]. We consider the static, spherically symmetric metric with cosmological constant Λ and Rindler-like term 2ar presented in this model, and we use the procedure by Rindler and Ishak [W. Rindler and M. Ishak, Phys. Rev. DPRVDAQ1550-7998 76, 043006 (2007).10.1103/PhysRevD.76.043006] to obtain the bending angle of light in this metric. Earlier work on light bending in this model by Carloni, Grumiller, and Preis [Phys. Rev. DPRVDAQ1550-7998 83, 124024 (2011)10.1103/PhysRevD.83.124024], using the method normally employed for asymptotically flat space-times, led to a conflicting result (caused by the Rindler-like term in the metric) of a bending angle that increases with the distance of closest approach r0 of the light ray from the centrally concentrated spherically symmetric matter distribution. However, when using the alternative approach for light bending in nonasymptotically flat space-times, we show that the linear Rindler-like term produces a small correction to the general relativistic result that is inversely proportional to r0. This will in turn affect the bounds on Rindler acceleration obtained earlier from light bending and casts doubts on the nature of the linear term 2ar in the metric.

  3. Review of a Few Selected Theories of Plates in Bending

    PubMed Central

    Vijayakumar, Kaza

    2014-01-01

    The author's recent investigations on plate theories form the basis to review development of plate theories. In spite of several review articles on plate theories reported in the literature, the present work is essentially due to Jemielita's inspiring article (1993). It is shown that methods of analysis based on vertical displacement as domain variable deal with solution of associated torsion problem in bending of plates. It is essential to use vertical displacement as face variable instead of domain variable in proper analysis of bending problems. PMID:27355028

  4. Origin of bending in uncoated microcantilever - Surface topography?

    SciTech Connect

    Lakshmoji, K.; Prabakar, K.; Tripura Sundari, S. Jayapandian, J.; Tyagi, A. K.; Sundar, C. S.

    2014-01-27

    We provide direct experimental evidence to show that difference in surface topography on opposite sides of an uncoated microcantilever induces bending, upon exposure to water molecules. Examination on opposite sides of the microcantilever by atomic force microscopy reveals the presence of localized surface features on one side, which renders the induced stress non-uniform. Further, the root mean square inclination angle characterizing the surface topography shows a difference of 73° between the opposite sides. The absence of deflection in another uncoated microcantilever having similar surface topography confirms that in former microcantilever bending is indeed induced by differences in surface topography.

  5. Elastostatic bending of a bimaterial plate with a circular interface

    NASA Astrophysics Data System (ADS)

    Ogbonna, Nkem

    2015-08-01

    The elastostatic bending of an arbitrarily loaded bimaterial plate with a circular interface is analysed. It is shown that the deflections in the composite solid are directly related to the deflection in the corresponding homogeneous material by integral and differential operators. It is further shown that, by a simple transformation of elastic constants, the Airy stress function induced in the composite by a stretching singularity can be deduced from the deflection induced by a bending singularity. This result is significant for reduction of mathematical labour and for systematic construction of solutions for more complex structures with circular geometry.

  6. Bending of solitons in weak and slowly varying inhomogeneous plasma

    SciTech Connect

    Mukherjee, Abhik Janaki, M. S. Kundu, Anjan

    2015-12-15

    The bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev-Petviashvili equation is obtained with a chosen unperturbed ion density profile. The exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, while the amplitude of the soliton remains constant.

  7. Optical characteristics of bending multimode superstructure fiber gratings.

    PubMed

    Fu, Ming-Yue; Liu, Wen-Fung; Sheng, Hao-Jan; Ai, Lung; Peng, Hsin-Wen; Tien, Chuen-Lin

    2009-09-01

    The dispersion characteristics of superstructure fiber gratings written in multimode fibers and side-polished multimode fibers are investigated at different bending curvatures. The experimental results show that the group time delay in multimode superstructure fiber gratings can be tuned more easily than that of superstructure gratings in single-mode fiber. This method can provide tunable dispersion of superstructure fiber gratings by controlling the bending curvatures for application in dispersion compensators, fiber sensors, or suitable optical filters of optical communication systems. PMID:19724306

  8. Test Equal Bending by Gravity for Space and Time

    NASA Astrophysics Data System (ADS)

    Sweetser, Douglas

    2009-05-01

    For the simplest problem of gravity - a static, non-rotating, spherically symmetric source - the solution for spacetime bending around the Sun should be evenly split between time and space. That is true to first order in M/R, and confirmed by experiment. At second order, general relativity predicts different amounts of contribution from time and space without a physical justification. I show an exponential metric is consistent with light bending to first order, measurably different at second order. All terms to all orders show equal contributions from space and time. Beautiful minimalism is Nature's way.

  9. Laminar flow heat transfer downstream from U-bends

    NASA Astrophysics Data System (ADS)

    Abdelmessih, Amanie Nassif

    1987-05-01

    The laminar flow heat transfer downstream from the unheated, vertical bends in horizontal U-tubes with electrically heated straight tube sections was investigated. For each test section, local axial and peripheral wall temperatures were measured and the local peripheral heat transfer coefficients at the various locations were calculated. The investigation permitted a better understanding of the interaction of the primary, secondary and tertiary flow patterns, i.e., the combination of forced and natural convection with the centrifugal effects. Also, a correlation was developed, which predicts the heat transfer coefficient downstream from an unheated U-bend, and which can be extended to straight tubes.

  10. Solution structure of an A-tract DNA bend.

    PubMed

    MacDonald, D; Herbert, K; Zhang, X; Pologruto, T; Lu, P; Polgruto, T

    2001-03-01

    The solution structure of a DNA dodecamer d(GGCAAAAAACGG)/d(CCGTTTTTTGCC) containing an A-tract has been determined by NMR spectroscopy with residual dipolar couplings. The structure shows an overall helix axis bend of 19 degrees in a geometry consistent with solution and gel electrophoresis experiments. Fourteen degrees of the bending occurs in the GC regions flanking the A-tract. The remaining 5 degrees is spread evenly over its six AT base-pairs. The A-tract is characterized by decreasing minor groove width from the 5' to the 3' direction along the A strand. This is a result of propeller twist in the AT pairs and the increasing negative inclination of the adenine bases at the 3' side of the run of adenine bases. The four central thymine bases all have negative inclination throughout the A-tract with an average value of -6.1 degrees. Although this negative inclination makes the geometry of the A-tract different from all X-ray structures, the proton on N6 of adenine and the O4 of thymine one step down the helix are within distance to form bifurcated hydrogen bonds. The 5' bend of 4 degrees occurs at the junction between the GC flank and the A-tract through a combination of tilt and roll. The larger 3' bend, 10 degrees, occurs in two base steps: the first composed of tilt, -4.1 degrees, and the second a combination of tilt, -4.2 degrees, and roll, 6.0 degrees. This second step is a direct consequence of the change in inclination between an adjacent cytosine base, which has an inclination of -12 degrees, and the next base, a guanine, which has 3 degrees inclination. This bend is a combination of tilt and roll. The large change in inclination allows the formation of a hydrogen bond between the protons of N4 of the 3' cytosine and the O6 of the next 3' base, a guanine, stabilizing the roll component in the bend. These structural features differ from existing models for A-tract bends.For comparison, we also determined the structure of the control sequence, d

  11. How protein-making machine bends without breaking

    SciTech Connect

    2011-01-01

    Scientists from several institutions including the U.S. Department of Energy's Lawrence Berkeley National Laboratory. They derived atomic-scale resolution structures of the cell's protein-making machine, the ribosome, at key stages of its job. The ability to bend but not break comes from this hinge within transfer RNA, which allows it to bend as much as 70 degrees when it passes through the ribosome during protein synthesis. The structures, developed primarily at Berkeley Lab's Advanced Light Source, reveal that the ribosome's ability to rotate an incredible amount without falling apart is due to the never-before-seen springiness of molecular widgets that hold it together.

  12. Preliminary survey of the mayflies (Ephemeroptera) and caddisflies (Trichoptera) of Big Bend Ranch State Park and Big Bend National Park

    PubMed Central

    Baumgardner, David E.; Bowles, David E.

    2005-01-01

    The mayfly (Insecta: Ephemeroptera) and caddisfly (Insecta: Trichoptera) fauna of Big Bend National Park and Big Bend Ranch State Park are reported based upon numerous records. For mayflies, sixteen species representing four families and twelve genera are reported. By comparison, thirty-five species of caddisflies were collected during this study representing seventeen genera and nine families. Although the Rio Grande supports the greatest diversity of mayflies (n=9) and caddisflies (n=14), numerous spring-fed creeks throughout the park also support a wide variety of species. A general lack of data on the distribution and abundance of invertebrates in Big Bend National and State Park is discussed, along with the importance of continuing this type of research. PMID:17119610

  13. Flow studies of highly loaded coal-water mixtures around bends and across horizontal sections. [Pressure loss with 90-degree bends and sweep bends

    SciTech Connect

    Wildman, D.J.; Ekmann, J.M.

    1984-01-01

    From the data taken in the flow loop, it appears that the coal-water mixtures (CWMs) prepared at PETC bracket the range of flow characteristics anticipated for commercial CWMs. Furthermore, the lower concentration slurries (55 wt % and 60 wt %) show nonhomogeneous behavior as a function of particle size and mixture velocity. Preliminary analysis of the pressure loss data around bends indicate 90-degree elbows are more efficient for the 60 wt % CWMS prepared with beneficiated coal, whereas the sweep bends yield lower pressure gradients for 65 wt % CWMs prepared with the same coal. The model developed for horizontal homogenous-nonhomogeneous laminar flow adequately predicts the pressure losses measured in the loop facility. The nonhomogeneous portion of the flow is restricted to a height of twenty percent of the pipe diameter. The accuracy of the model depends heavily on viscosity-shear-rate data measured in the rheology laboratory. The nonhomogenous flow pressure gradient is calculated via the Durand-Condolios equation. The homogeneous flow pressure gradient is calculated using the classical laminar flow equation. The model developed for sweep bends satisfactorily predicts the pressure losses measured. The revised model predicted the measured pressure losses with an index of determination of 0.95. The model consists of revising the pressure loss equation of Ito to include a parameter that is a function of the Reynolds number. 11 refs.

  14. Bending-induced mode non-degeneracy and coupling in chalcogenide negative curvature fibers.

    PubMed

    Wei, Chengli; Menyuk, Curtis R; Hu, Jonathan

    2016-05-30

    We study bend loss in chalcogenide negative curvature fibers with different polarizations, different tube wall thicknesses, and different bend directions relative to the mode polarization. The coupling between the core mode and tube modes induces bend loss peaks in the two non-degenerate modes at the same bend radius. There is as much as a factor of 28 difference between the losses of the two polarization modes. The fiber with a larger tube wall thickness, corresponding to a smaller inner tube diameter, can sustain a smaller bend radius. The bend loss is sensitive to the bend direction when coupling occurs between the core mode and tube modes. A bend loss of 0.2 dB/m at a bend radius of 16 cm, corresponding to 0.2 dB/turn, can be achieved in a chalcogenide negative curvature fiber. PMID:27410139

  15. Integration of a photonic crystal polarization beam splitter and waveguide bend.

    PubMed

    Zheng, Wanhua; Xing, Mingxin; Ren, Gang; Johnson, Steven G; Zhou, Wenjun; Chen, Wei; Chen, Lianghui

    2009-05-11

    In this work, we present the design of an integrated photonic-crystal polarization beam splitter (PC-PBS) and a low-loss photonic-crystal 60 degrees waveguide bend. Firstly, the modal properties of the PC-PBS and the mechanism of the low-loss waveguide bend are investigated by the two-dimensional finite-difference time-domain (FDTD) method, and then the integration of the two devices is studied. It shows that, although the individual devices perform well separately, the performance of the integrated circuit is poor due to the multi-mode property of the PC-PBS. By introducing deformed airhole structures, a single-mode PC-PBS is proposed, which significantly enhance the performance of the circuit with the extinction ratios remaining above 20 dB for both transverse-electric (TE) and transverse-magnetic (TM) polarizations. Both the specific result and the general idea of integration design are promising in the photonic crystal integrated circuits in the future. PMID:19434199

  16. 2. VIEW OF CENTRAL BEND OF LOWER DIAGONAL NO. 1 ...

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

    2. VIEW OF CENTRAL BEND OF LOWER DIAGONAL NO. 1 DRAIN, LOOKING 2932 EAST OF NORTH. - Truckee-Carson Irrigation District, Lower Diagonal No. 1 Drain, Bounded by West Gate Road & Weapons Delivery Road, Naval Air Station Fallon, Fallon, Churchill County, NV

  17. The Clinch Bend Regional Industrial Site and economic development opportunities

    SciTech Connect

    1995-12-31

    This effort focuses initially on the Clinch Bend site. Other sites and developable tracts of land are identified with the assistance of communities in proximity to Oak Ridge, the State of Tennessee, and others, and compared with the projected site requirements for large industrial facilities.

  18. Bending behavior of prestressed-concrete beams at low temperatures

    SciTech Connect

    Okada, T.; Imai, M.; Nagasawa, Y.; Kunishima, M.

    1982-01-01

    The report describes the results of experimental studies on the bending behavior and creep characteristics of prestressed concrete beams at temperatures from -100 C to +20 C. In addition, the mechanical properties pertinent to the design of liquified natural gas storage tanks, at low temperatures, is investigated.

  19. Teaching Cultural Geography with "Bend It like Beckham"

    ERIC Educational Resources Information Center

    Algeo, Katie

    2007-01-01

    The British film "Bend It Like Beckham" (2002) is pedagogically useful in the cultural geography classroom for engaging students with core concepts, such as ethnicity, migration, acculturation, and assimilation, and with more advanced modes of analysis, such as the social construction of identity. Although the film depicts a particular ethnic…

  20. 'It's still bending': verbal suggestion and alleged psychokinetic ability.

    PubMed

    Wiseman, Richard; Greening, Emma

    2005-02-01

    Some alleged psychics appear to be able to deform metallic objects, such as keys and cutlery, by thought alone. This paper describes two studies that examined whether one aspect of these demonstrations could be created by verbal suggestion. In the first study, participants were shown a videotape in which a fake psychic placed a bent key on a table. Participants in one condition heard the fake psychic suggest that the key was continuing to bend, whilst those in the other condition did not. Participants in the suggestion condition were significantly more likely to report that the key continued to bend. These findings were replicated in the second study. In addition, participants who reported that the key continued to bend displayed a significantly higher level of confidence in their testimony than others, and were significantly less likely to recall that the fake psychic had suggested the continued bending of the key. Neither experiment revealed any differences between participants who expressed a prior belief in the paranormal compared with those who did not. The paper discusses the implications of these results for the psychology of suggestion and the assessment of eyewitness testimony for anomalous events. PMID:15826327

  1. 10. MOVABLE BED SEDIMENTATION MODELS. DOGTOOTH BEND MODEL (MODEL SCALE: ...

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

    10. MOVABLE BED SEDIMENTATION MODELS. DOGTOOTH BEND MODEL (MODEL SCALE: 1' = 400' HORIZONTAL, 1' = 100' VERTICAL), AND GREENVILLE BRIDGE MODEL (MODEL SCALE: 1' = 360' HORIZONTAL, 1' = 100' VERTICAL). - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

  2. A Second Look at Brian Simon's "Bending the Rules"

    ERIC Educational Resources Information Center

    Cox, Sue

    2016-01-01

    In this article the author revisits an important book: Brian Simon's "Bending the Rules: the Baker reform of education." Written by a key figure in the history of the journal FORUM as well as in the history of education, Simon's book documented the features of the Education Reform Bill of 1987 (the precursor to the Education Reform Act…

  3. Photoacoustic elastic bending in thin film—Substrate system

    SciTech Connect

    Todorović, D. M.; Rabasović, M. D.; Markushev, D. D.

    2013-12-07

    Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm.

  4. Water-rich bending faults at the Middle America Trench

    NASA Astrophysics Data System (ADS)

    Naif, Samer; Key, Kerry; Constable, Steven; Evans, Rob L.

    2015-09-01

    The portion of the Central American margin that encompasses Nicaragua is considered to represent an end-member system where multiple lines of evidence point to a substantial flux of subducted fluids. The seafloor spreading fabric of the incoming Cocos plate is oriented parallel to the trench such that flexural bending at the outer rise optimally reactivates a dense network of normal faults that extend several kilometers into the upper mantle. Bending faults are thought to provide fluid pathways that lead to serpentinization of the upper mantle. While geophysical anomalies detected beneath the outer rise have been interpreted as broad crustal and upper mantle hydration, no observational evidence exists to confirm that bending faults behave as fluid pathways. Here we use seafloor electromagnetic data collected across the Middle America Trench (MAT) offshore of Nicaragua to create a comprehensive electrical resistivity image that illuminates the infiltration of seawater along bending faults. We quantify porosity from the resistivity with Archie's law and find that our estimates for the abyssal plain oceanic crust are in good agreement with independent observations. As the Cocos crust traverses the outer rise, the porosity of the dikes and gabbros progressively increase from 2.7% and 0.7% to 4.8% and 1.7%, peaking within 20 km of the trench axis. We conclude that the intrusive crust subducts twice as much pore water as previously thought, significantly raising the flux of fluid to the seismogenic zone and the mantle wedge.

  5. Bed plate for rail bending machine, Johnson Company, Johnstown, Pa. ...

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

    Bed plate for rail bending machine, Johnson Company, Johnstown, Pa. Scale 3 inches - 1 ft, Jan 30th 1893, drawing number 14929. (Photograph of drawing held at the Johnstown Corporation General Office,Johnstown, Pennsylvania) - Johnson Steel Street Rail Company, 525 Central Avenue, Johnstown, Cambria County, PA

  6. Tool nos. 277 and 2201, details for bending machine, Johnson ...

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

    Tool nos. 277 and 2201, details for bending machine, Johnson Company, Johnstown, Pa. Scale 3 inches - 1 ft, Feb 13th 1893, drawing number 15098. (Photograph of drawing held at the Johnstown Corporation General Office, Johnstown, Pennsylvania) - Johnson Steel Street Rail Company, 525 Central Avenue, Johnstown, Cambria County, PA

  7. 78 FR 34553 - Amendment of Class E Airspace; Bend, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... Bend, OR (78 FR 13843). Interested parties were invited to participate in this rulemaking effort by... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  8. VIEW OF BEND IN CEDAR DRIVE WITH 603 CEDAR DRIVE ...

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

    VIEW OF BEND IN CEDAR DRIVE WITH 603 CEDAR DRIVE ON RIGHT. VIEW FACING NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  9. Twist and writhe of a DNA loop containing intrinsic bends.

    PubMed Central

    Bauer, W R; Lund, R A; White, J H

    1993-01-01

    The finite-element method of solid mechanics is applied to calculation of the three-dimensional structure of closed circular DNA, modeled as an elastic rod subject to large motions. The results predict the minimum elastic energy conformation of a closed loop of DNA as a function of relaxed equilibrium configuration and linking number (Lk). We apply the method to four different starting states: a straight rod, two rods containing either one or two 20 degrees bends, and a circular O-ring. The results, here at low superhelix density, show the changes in writhe (Wr) and in twist (Tw) as Lk is progressively lowered. The presence of even a single intrinsic bend reduces significantly the linking number change at which Wr first appears, compared to an initially straight, bend-free rod. The presence of two in-phase bends, situated at opposite ends of a diameter, leads to the formation of at least two distinct regions of different but relatively uniform Tw increment. The O-ring begins to writhe immediately upon reduction of Lk, and the Tw increment distribution is sinusoidal along the rod. The mechanics calculations, unlike other theoretical approaches, permit us to calculate Tw and Wr independent of the constraint of constant Lk. Images PMID:8430093

  10. Twist and writhe of a DNA loop containing intrinsic bends.

    PubMed

    Bauer, W R; Lund, R A; White, J H

    1993-02-01

    The finite-element method of solid mechanics is applied to calculation of the three-dimensional structure of closed circular DNA, modeled as an elastic rod subject to large motions. The results predict the minimum elastic energy conformation of a closed loop of DNA as a function of relaxed equilibrium configuration and linking number (Lk). We apply the method to four different starting states: a straight rod, two rods containing either one or two 20 degrees bends, and a circular O-ring. The results, here at low superhelix density, show the changes in writhe (Wr) and in twist (Tw) as Lk is progressively lowered. The presence of even a single intrinsic bend reduces significantly the linking number change at which Wr first appears, compared to an initially straight, bend-free rod. The presence of two in-phase bends, situated at opposite ends of a diameter, leads to the formation of at least two distinct regions of different but relatively uniform Tw increment. The O-ring begins to writhe immediately upon reduction of Lk, and the Tw increment distribution is sinusoidal along the rod. The mechanics calculations, unlike other theoretical approaches, permit us to calculate Tw and Wr independent of the constraint of constant Lk. PMID:8430093

  11. Bending strength model for internal spur gear teeth

    NASA Technical Reports Server (NTRS)

    Savage, Michael; Rubadeux, K. L.; Coe, H. H.

    1995-01-01

    Internal spur gear teeth are normally stronger than pinion teeth of the same pitch and face width since external teeth are smaller at the base. However, ring gears which are narrower have an unequal addendum or are made of a material with a lower strength than that of the meshing pinion may be loaded more critically in bending. In this study, a model for the bending strength of an internal gear tooth as a function of the applied load pressure angle is presented which is based on the inscribed Lewis constant strength parabolic beam. The bending model includes a stress concentration factor and an axial compression term which are extensions of the model for an external gear tooth. The geometry of the Lewis factor determination is presented, the iteration to determine the factor is described, and the bending strength J factor is compared to that of an external gear tooth. This strength model will assist optimal design efforts for unequal addendum gears and gears of mixed materials.

  12. Design and development of a MEMS capacitive bending strain sensor

    NASA Astrophysics Data System (ADS)

    Aebersold, J.; Walsh, K.; Crain, M.; Martin, M.; Voor, M.; Lin, J.-T.; Jackson, D.; Hnat, W.; Naber, J.

    2006-05-01

    The design, modeling, fabrication and testing of a MEMS-based capacitive bending strain sensor utilizing a comb drive is presented. This sensor is designed to be integrated with a telemetry system that will monitor changes in bending strain to assist with the diagnosis of spinal fusion. ABAQUS/CAE finite-element analysis (FEA) software was used to predict sensor actuation, capacitance output and avoid material failure. Highly doped boron silicon wafers with a low resistivity were fabricated into an interdigitated finger array employing deep reactive ion etching (DRIE) to create 150 µm sidewalls with 25 µm spacing between the adjacent fingers. The sensor was adhered to a steel beam and subjected to four-point bending to mechanically change the spacing between the interdigitated fingers as a function of strain. As expected, the capacitance output increased as an inverse function of the spacing between the interdigitated fingers. At the unstrained state, the capacitive output was 7.56 pF and increased inversely to 17.04 pF at 1571 µɛ of bending strain. The FEA and analytical models were comparable with the largest differential of 0.65 pF or 6.33% occurring at 1000 µɛ. Advantages of this design are a dice-free process without the use of expensive silicon-on-insulator (SOI) wafers.

  13. Cumberland Extension entering Magnolia Bend in West Virginia. After passing ...

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

    Cumberland Extension entering Magnolia Bend in West Virginia. After passing over the Third Potomac and C&O Canal Crossing, the line curves over the former B&O Railroad at Bridge No. 1363, First B&O Crossing in foreground, looking northeast. - Western Maryland Railway, Cumberland Extension, Pearre to North Branch, from WM milepost 125 to 160, Pearre, Washington County, MD

  14. Optimal semi-active damping of cables with bending stiffness

    NASA Astrophysics Data System (ADS)

    Boston, C.; Weber, F.; Guzzella, L.

    2011-05-01

    The problem of optimal semi-active damping of cables with bending stiffness is investigated with an evolutionary algorithm. The developed damping strategy is validated on a single strand cable with a linear motor attached close to the anchor position. The motor is operated in force feedback mode during free decay of cable vibrations, during which time the decay ratios of the cable modes are measured. It is shown from these experiments that the damping ratios predicted in simulation are close to those measured. The semi-active damping strategy found by the evolutionary algorithm is very similar in character to that for a cable without bending stiffness, being the superposition of an amplitude-dependent friction and negative stiffness element. However, due to the bending stiffness of the cable, the tuning of the above elements as a function of the relevant cable parameters is greatly altered, especially for damper positions close to a fixed end anchor, where the mode shape depends strongly on bending stiffness. It is furthermore demonstrated that a semi-active damper is able to dissipate significantly more energy for a cable with simply supported ends compared to fixed ends due to larger damper strokes and thereby increased energy dissipation in the device.

  15. Bend-twist coupling potential of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Fedorov, V.; Berggreen, C.

    2014-06-01

    In the present study an evaluation of the potential for bend-twist coupling effects in wind turbine blades is addressed. A method for evaluation of the coupling magnitude based on the results of finite element modeling and full-field displacement measurements obtained by experiments is developed and tested on small-scale coupled composite beams. In the proposed method the coupling coefficient for a generic beam is introduced based on the Euler-Bernoulli beam formulation. By applying the developed method for analysis of a commercial wind turbine blade structure it is demonstrated that a bend-twist coupling magnitude of up to 0.2 is feasible to achieve in the baseline blade structure made of glass-fiber reinforced plastics. Further, by substituting the glass-fibers with carbon-fibers the coupling effect can be increased to 0.4. Additionally, the effect of introduction of bend-twist coupling into a blade on such important blade structural properties as bending and torsional stiffness is demonstrated.

  16. Photoacoustic elastic bending in thin film—Substrate system

    NASA Astrophysics Data System (ADS)

    Todorović, D. M.; Rabasović, M. D.; Markushev, D. D.

    2013-12-01

    Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm.

  17. Modeling bicortical screws under a cantilever bending load.

    PubMed

    James, Thomas P; Andrade, Brendan A

    2013-12-01

    Cyclic loading of surgical plating constructs can precipitate bone screw failure. As the frictional contact between the plate and the bone is lost, cantilever bending loads are transferred from the plate to the head of the screw, which over time causes fatigue fracture from cyclic bending. In this research, analytical models using beam mechanics theory were developed to describe the elastic deflection of a bicortical screw under a statically applied load. Four analytical models were developed to simulate the various restraint conditions applicable to bicortical support of the screw. In three of the models, the cortical bone near the tip of the screw was simulated by classical beam constraints (1) simply supported, (2) cantilever, and (3) split distributed load. In the final analytical model, the cortices were treated as an elastic foundation, whereby the response of the constraint was proportional to screw deflection. To test the predictive ability of the new analytical models, 3.5 mm cortical bone screws were tested in a synthetic bone substitute. A novel instrument was developed to measure the bending deflection of screws under radial loads (225 N, 445 N, and 670 N) applied by a surrogate surgical plate at the head of the screw. Of the four cases considered, the analytical model utilizing an elastic foundation most accurately predicted deflection at the screw head, with an average difference of 19% between the measured and predicted results. Determination of the bending moments from the elastic foundation model revealed that a maximum moment of 2.3 N m occurred near the middle of the cortical wall closest to the plate. The location of the maximum bending moment along the screw axis was consistent with the fracture location commonly observed in clinical practice. PMID:24105350

  18. Experimental observation of surface states and Landau levels bending in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Yin, Long-Jing; Zhang, Yu; Qiao, Jia-Bin; Li, Si-Yu; He, Lin

    2016-03-01

    We report on microscopic measurements of the low-energy electronic structures both at the zigzag and armchair edges of bilayer graphene using scanning tunneling microscopy and spectroscopy (STM and STS). We have found that, both in the absence and in the presence of a magnetic field, an almost zero-energy peak in the density of states was localized at the zigzag edges, as expected for the surface states at the zigzag edges of bilayer graphene. In the quantum Hall regime, we have clearly observed Landau levels bending away from the charge neutrality point near both the zigzag and armchair edges. Such a result is direct evidence for the evolution of Landau levels into quantum Hall edge states in graphene bilayers. Our experiment indicates that it is possible to explore rich quantum Hall physics in graphene systems using STM and STS.

  19. Theory of using magnetic deflections to combine charged particle beams.

    SciTech Connect

    Doyle, Barney Lee; Steckbeck, Mackenzie K.

    2014-09-01

    Several radiation effects projects in the Ion Beam Lab (IBL) have recently required two disparate charged particle beams to simultaneously strike a single sample through a single port of the target chamber. Because these beams have vastly different mass- energy products (MEP), the low MEP beam requires a large angle of deflection toward the sample by a bending electromagnet. A second electromagnet located further upstream provides a means to compensate for the small angle deflection experienced by the high MEP beam during its path through the bending magnet. This paper derives the equations used to select the magnetic fields required by these two magnets to achieve uniting both beams at the target sample. A simple result was obtained when the separation of the two magnets was equivalent to the distance from the bending magnet to the sample, and the equations is given by: , 1 2 c s c s r B B r where and are the magnetic fields in the steering and bending magnet and is s B c B c s r r the ratio of the radii of the bending magnet to that of the steering magnet. This result is not dependent upon the parameters of the high MEP beam, i.e. energy, mass, charge state. Therefore, once the field of the bending magnet is set for the low MEP beam, and the field in the steering magnet is set as indicted in the equation, the trajectory path of any high MEP beam will be directed into the sample. (page intentionally left blank)

  20. Tension, compression, and bending of superelastic shape memory alloy tubes

    NASA Astrophysics Data System (ADS)

    Reedlunn, Benjamin; Churchill, Christopher B.; Nelson, Emily E.; Shaw, John A.; Daly, Samantha H.

    2014-02-01

    While many uniaxial tension experiments of shape memory alloys (SMAs) have been published in the literature, relatively few experimental studies address their behavior in compression or bending, despite the prevalence of this latter deformation mode in applications. In this study, superelastic NiTi tubes from a single lot of material were characterized in tension, compression, and pure bending, which allowed us to make direct comparisons between the deformation modes for the first time. Custom built fixtures were used to overcome some long-standing experimental difficulties with performing well-controlled loading and accurate measurements during uniaxial compression (avoiding buckling) and large-rotation bending. In all experiments, the isothermal, global, mechanical responses were measured, and stereo digital image correlation (DIC) was used to measure the evolution of the strain fields on the tube's outer surface.As is characteristic of textured NiTi, our tubes exhibited significant tension-compression asymmetry in their uniaxial responses. Stress-induced transformations in tension exhibited flat force plateaus accompanied by strain localization and propagation. No such localization, however, was observed in compression, and the stress "plateaus" during compression always maintained a positive tangent modulus. While our uniaxial results are similar to the observations of previous researchers, the DIC strain measurements provided details of localized strain behavior with more clarity and allowed more quantitative measurements to be made. Consistent with the tension-compression asymmetry, our bending experiments showed a significant shift of the neutral axis towards the compression side. Furthermore, the tube exhibited strain localization on the tension side, but no localization on the compression side during bending. This is a new observation that has not been explored before. Detailed analysis of the strain distribution across the tube diameter revealed that the

  1. Influence of Additional Tensile Force on Springback of Tube Under Rotary Draw Bending

    NASA Astrophysics Data System (ADS)

    E, Daxin; Guan, Zhiping; Chen, Jisheng

    2012-11-01

    According to the characteristics of tube under rotary draw bending, the formulae were derived to calculate the springback angles of tubes subjected to combined bending and additional tension. Especially, as the neutral layer (NL) moves to the inner concave surface of the bend, the analytical values agree very well with the experimental results. The analysis shows that the additional tensile force causes the movement of the NL toward the bending center and makes the deformation behavior under rotary draw bending or numerically controlled (NC) bending different with that under pure bending, and also it could enlarge the springback angle if taking the movement of the NL into consideration. In some range, the springback angle would increase slightly with larger wall thickness/diameter ratio and decrease with wall thinning. The investigation could provide reference for the analysis of rotary draw bending, the design of NC tube bender and the related techniques.

  2. Development of finite element analysis method for three-dimensional hot bending and direct quench (3DQ) process

    NASA Astrophysics Data System (ADS)

    Kubota, Hiroaki; Tomizawa, Atsushi; Yamamoto, Kenji; Okada, Nobuhiro

    2013-05-01

    The automotive industry has been focusing on developing lighter vehicles to improve fuel economy and crash safety. In order to meet these requirements, Three Dimensional Hot Bending and Direct Quench (3DQ) Technology has been developed, which enables a manufacturer to form hollow tubular automotive parts with a tensile strength of 1,470 MPa or over. 3DQ is a type of consecutive forming that allows bending and quenching at the same time, with a tube feeding device, an induction heater, a cooling device, and a bending device. In this research, a coupled thermomechanical-metallurgical finite element analysis (FEA) method has been developed to investigate the deformation behavior and to predict the forming capability of 3DQ. In the developed FEA procedure, the temperature distribution was calculated with electro magnetic and heat transfer analysis, and the flow stress was defined by transformation models and linear mixture rule. An experimental formula was used to track the ferrite-austenite transformation, and a Koistinen-Marburger relationship was employed to describe austenite-martensite change. The simulated results were compared with the experimental measurements, and the effectiveness of the developed FEA method was confirmed. Furthermore, the deformation characteristics of 3DQ, such as the wrinkling limit and the thickness change, were investigated, and simple equations to describe them were proposed.

  3. Effect of ball geometry on endurance limit in bending of drilled balls

    NASA Technical Reports Server (NTRS)

    Munson, H. E.

    1975-01-01

    Four designs of drilled (cylindrically hollow) balls were tested for resistance to bending fatigue. Bending fatigue has been demonstrated to be a limiting factor in previous evaluations of the drilled ball concept. A web reinforced drilled ball was most successful in resisting bending fatigue. Another design of through drilled design, involving a heavier wall than the standard reference ball, also showed significant improvement in resistance to bending fatigue.

  4. OPTIMIZING THE DYNAMIC APERTURE FOR TRIPLE BEND ACHROMATIC LATTICES.

    SciTech Connect

    KRAMER, S.L.; BENGTSSON, J.

    2006-06-26

    The Triple Bend Achromatic (TBA) lattice has the potential for lower natural emittance per period than the Double Bend Achromatic (DBA) lattice for high brightness light sources. However, the DBA has been chosen for 3rd generation light sources more often due to the higher number of undulator straight section available for a comparable emittance. The TBA has considerable flexibility in linear optics tuning while maintaining this emittance advantage. We have used the tune and chromaticity flexibility of a TBA lattice to minimize the lowest order nonlinearities to implement a 3rd order achromatic tune, while maintaining a constant emittance. This frees the geometric sextupoles to counter the higher order nonlinearities. This procedure is being used to improve the nonlinear dynamics of the TBA as a proposed lattice for NSLS-II facility. The flexibility of the TBA lattice will also provide for future upgrade capabilities of the beam parameters.

  5. Bending and Torsion Load Alleviator With Automatic Reset

    NASA Technical Reports Server (NTRS)

    delaFuente, Horacio M. (Inventor); Eubanks, Michael C. (Inventor); Dao, Anthony X. (Inventor)

    1996-01-01

    A force transmitting load alleviator apparatus and method are provided for rotatably and pivotally driving a member to be protected against overload torsional and bending (moment) forces. The load alleviator includes at least one bias spring to resiliently bias cam followers and cam surfaces together and to maintain them in locked engagement unless a predetermined load is exceeded whereupon a center housing is pivotal or rotational with respect to a crown assembly. This pivotal and rotational movement results in frictional dissipation of the overload force by an energy dissipator. The energy dissipator can be provided to dissipate substantially more energy from the overload force than from the bias force that automatically resets the center housing and crown assembly to the normally fixed centered alignment. The torsional and bending (moment) overload levels can designed independently of each other.

  6. Vibrational transitions of coupled stretching and bending overtones in chloroform

    NASA Astrophysics Data System (ADS)

    Beckmann, Kai; Gerhards, Markus; Kleist, Einhard; Bettermann, Hans

    1995-08-01

    The intensities and frequencies of Fermi-coupled stretching and bending overtone transitions in CHCl3 were calculated by means of a variational method. Symmetrized two-dimensional ab initio potential and dipole moment surfaces were determined at the MP2 level using the 6-31G** basis set. The Hamiltonian for the CH- stretching motion and the simultaneously excited twofold degenerate CH- bending vibration is expressed most easily in cylindrical coordinates. Absorption intensities up to the Δv=7 CH-stretching overtone above 16 300 cm-1 are calculated and are compared to former experimental values and theoretical results. New quantitative intracavity measurements for the N=6 polyad are presented. Relative errors between absolute experimental intensities and the calculated values are less than 30%.

  7. Bending stresses due to torsion in cantilever box beams

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1935-01-01

    The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests.

  8. Interaction between bending and tension forces in bilayer membranes.

    PubMed Central

    Secomb, T W

    1988-01-01

    A theoretical analysis is presented of the bending mechanics of a membrane consisting of two tightly-coupled leaflets, each of which shears and bends readily but strongly resists area changes. Structures of this type have been proposed to model biological membranes such as red blood cell membrane. It is shown that when such a membrane is bent, anisotropic components of resultant membrane tension (shear stresses) are induced, even when the tension in each leaflet is isotropic. The induced shear stresses increase as the square of the membrane curvature, and become significant for moderate curvatures (when the radius of curvature is much larger than the distance between the leaflets). This effect has implications for the analysis of shape and deformation of freely suspended and flowing red blood cells. PMID:3224154

  9. The bending of cell sheets--from folding to rolling.

    PubMed

    Keller, Ray; Shook, David

    2011-01-01

    The bending of cell sheets plays a major role in multicellular embryonic morphogenesis. Recent advances are leading to a deeper understanding of how the biophysical properties and the force-producing behaviors of cells are regulated, and how these forces are integrated across cell sheets during bending. We review work that shows that the dynamic balance of apical versus basolateral cortical tension controls specific aspects of invagination of epithelial sheets, and recent evidence that tissue expansion by growth contributes to neural retinal invagination in a stem cell-derived, self-organizing system. Of special interest is the detailed analysis of the type B inversion in Volvox reported in BMC Biology by Höhn and Hallmann, as this is a system that promises to be particularly instructive in understanding morphogenesis of any monolayered spheroid system. PMID:22206439

  10. Bending and buckling behavior analysis of foamed metal circular plate.

    PubMed

    Fan, Jian Ling; Ma, Lian Sheng; Zhang, Lu; De Su, Hou

    2016-01-01

    This paper establishes a density gradient model along the thickness direction of a circular plate made of foamed material. Based on the first shear deformation plate theory, the result is deduced that the foamed metal circular plate with graded density along thickness direction yields axisymmetric bending problem under the action of uniformly distributed load, and the analytical solution is obtained by solving the governing equation directly. The analyses on two constraint conditions of edge radial clamping and simply supported show that the density gradient index and external load may affect the axisymmetric bending behavior of the plate. Then, based on the classical plate theory, the paper analyzes the behavior of axisymmetric buckling under radial pressure applied on the circular plate. Shooting method is used to obtain the critical load, and the effects of gradient nature of material properties and boundary conditions on the critical load of the plate are analyzed. PMID:27339281

  11. Coupled Torsional and Bending Vibrations of Actively Controlled Drillstrings

    NASA Astrophysics Data System (ADS)

    YIGIT, A. S.; CHRISTOFOROU, A. P.

    2000-06-01

    The dynamics of actively controlled drillstrings is studied. The equations of motion are derived using a lumped parameter model in which the coupling between torsional and bending vibrations is considered. The model also includes the dynamics of the rotary drive system which contains the rotary table, the gearbox and an armature controlled DC motor. The interactions between the drillstring and the borehole which are considered, include the impacts of collars with the borehole wall as well as bit rotation-dependent weight and torque on bit (WOB and TOB). Simulation results obtained by numerically solving the equations of motion are in close qualitative agreement with field and laboratory observations regarding stick-slip oscillations. A linear quadratic regulator (LQR) controller is designed based on a linearized model and is shown to be effective in eliminating this type of oscillations. It is also shown that for some operational parameters the control action may excite large bending vibrations due to coupling with the torsional motion.

  12. 46 CFR 56.80-15 - Heat treatment of bends and formed components.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Heat treatment of bends and formed components. 56.80-15 Section 56.80-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Bending and Forming § 56.80-15 Heat treatment of bends and formed components. (a) Carbon-steel piping that has...

  13. 33 CFR 3.65-20 - Sector North Bend Search and Rescue Mission Coordinator Zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Sector North Bend Search and... CAPTAIN OF THE PORT ZONES Thirteenth Coast Guard District § 3.65-20 Sector North Bend Search and Rescue... Sector North Bend's Search and Rescue Mission Coordinator Zone start at a point 45°12.0′ N. latitude,...

  14. 33 CFR 3.65-20 - Sector North Bend Search and Rescue Mission Coordinator Zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Sector North Bend Search and... CAPTAIN OF THE PORT ZONES Thirteenth Coast Guard District § 3.65-20 Sector North Bend Search and Rescue... Sector North Bend's Search and Rescue Mission Coordinator Zone start at a point 45°12.0′ N. latitude,...

  15. 46 CFR 56.80-15 - Heat treatment of bends and formed components.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference; see 46 CFR 56.01-2) may be used without a postheat treatment. (e) For other materials the heat... 46 Shipping 2 2010-10-01 2010-10-01 false Heat treatment of bends and formed components. 56.80-15... PIPING SYSTEMS AND APPURTENANCES Bending and Forming § 56.80-15 Heat treatment of bends and...

  16. Anomalous magnetoresistance in magnetized topological insulator cylinders

    SciTech Connect

    Siu, Zhuo Bin; Jalil, Mansoor B. A.

    2015-05-07

    The close coupling between the spin and momentum degrees of freedom in topological insulators (TIs) presents the opportunity for the control of one to manipulate the other. The momentum can, for example, be confined on a curved surface and the spin influenced by applying a magnetic field. In this work, we study the surface states of a cylindrical TI magnetized in the x direction perpendicular to the cylindrical axis lying along the z direction. We show that a large magnetization leads to an upwards bending of the energy bands at small |k{sub z}|. The bending leads to an anomalous magnetoresistance where the transmission between two cylinders magnetized in opposite directions is higher than when the cylinders are magnetized at intermediate angles with respect to each other.

  17. Buoyancy, bending, and seismic visibility in deep slab stagnation

    NASA Astrophysics Data System (ADS)

    Bina, Craig R.; Kawakatsu, Hitoshi; Suetsugu, D.; Bina, C.; Inoue, T.; Wiens, D.; Jellinek, M.

    2010-11-01

    The petrological consequences of deep subhorizontal deflection ("stagnation") of subducting slabs should affect both apparent seismic velocity structures and slab morphology. We construct kinematic thermal models of stagnant slabs and perform thermodynamic modeling of the consequent perturbation of high-pressure phase transitions in mantle minerals, focusing upon Japan as our study area. We calculate associated thermo-petrological buoyancy forces and bending moments which (along with other factors such as viscosity variations and rollback dynamics) may contribute to slab deformation. We consider effects of variations in depth of stagnation, post-stagnation dip angle, phase transition sharpness, transition triplication due to multiple intersection of geotherms with phase boundaries, and potential persistence of metastable phases due to kinetic hindrance. We also estimate seismic velocity anomalies, as might be imaged by seismic tomography, and corresponding seismic velocity gradients, as might be imaged by receiver-function analysis. We find that buoyant bending moment gradients of petrological origin at the base of the transition zone may contribute to slab stagnation. Such buoyancy forces vary with the depth at which stagnation occurs, so that slabs may seek an equilibrium slab stagnation depth. Metastable phase bending moment gradients further enhance slab stagnation, but they thermally decay after ∱/4600•700 km of horizontal travel, potentially allowing stagnant slabs to descend into the lower mantle. Stagnant slabs superimpose zones of negative velocity gradient onto a depressed 660-km seismic discontinuity, affecting the seismological visibility of such features. Seismologically resolvable details should depend upon both stagnation depth and the nature of the imaging technique (travel-time tomography vs. boundary-interaction phases). While seismic tomography appears to yield images of stagnant slabs, discontinuity topography beneath Japan resolved by

  18. Geomorpho-tectonic evolution of the Jamaican restraining bend

    NASA Astrophysics Data System (ADS)

    Domínguez-González, Leomaris; Andreani, Louis; Stanek, Klaus P.; Gloaguen, Richard

    2015-01-01

    This work applies recent advances in tectonic geomorphology in order to understand the geomorphic evolution of the Jamaican restraining bend located along the Caribbean-Gonâve-North American plate boundary. We propose a classification of landscapes according to their erosional stages. The approach is mainly based on the combination of two DEM-based geomorphic indices: the hypsometric integral which highlights elevated surfaces, and the surface roughness which increases when the relief is incised by the drainage network. River longitudinal profiles were also analyzed as the drainage network responds quickly to base-level change triggered by external forcing such as tectonics. Anomalies in river profiles (knickpoints and convex segments) were mapped using stream length-gradient (SL) and normalized steepness (ksn) indices. The results provide new insights for understanding the complex evolution of the Jamaican restraining bend. Three main morphotectonic regions were identified in Jamaica: (1) the Blue Mountain-Wagwater unit located at the eastern tip of the island, (2) the Jamaican highlands plateau which covers most of the northern and central areas and (3) the tilted block province located along the southern part of Jamaica. Each region has a specific morphological signature which marks a different stage in the Late Miocene to present evolution of the Jamaican restraining bend. The evolution of the bend is mainly associated with the western propagation of major E-trending strike-slip faults and NW-trending thrusts. In the western and central parts of Jamaica the present-day motion between the Caribbean plate and the Gonâve microplate is broadly distributed along several structures, while in the easternmost part of the island this motion seems to be almost completely accommodated along the Blue Mountain range and the Plantain-Garden Fault.

  19. Problems with cryogenic operation of piezoelectric bending elements

    NASA Astrophysics Data System (ADS)

    Duffield, C. L.; Moreland, John; Fickett, F. R.

    1986-05-01

    Piezoelectric bimorphs constructed from lead titanate-zirconate (PZT) ceramic bonded to a brass sheet have been tested at cryogenic temperatures to determine their suitability for use in a low-temperature micropositioner. Experimental data are presented on bimorph sensitivity (displacement per volt) as a function of the number of temperature cycles. Results indicate that bimorphs of this type cannot be calibrated because of irreversible changes in the bending characteristics that occur while cycling from room temperature to 4 K.

  20. [On fatigue bending strength of PMMA-specimen (author's transl)].

    PubMed

    Rojczyk, M; Rojczyk-Pflüger, J

    1980-01-01

    The fatigue response of PMMA-specimen was tested under cyclic bending of 1.5 Hz in a particularly designed testing device. Specimen were tested that a "Wöhler" curve and the corresponding fatigue strength could be evaluated. The fatigue strength was reached after a comparatively short time and ranged in the order of 33 per cent of static breaking strength. PMID:7447658

  1. New triangular and quadrilateral plate-bending finite elements

    NASA Technical Reports Server (NTRS)

    Narayanaswami, R.

    1974-01-01

    A nonconforming plate-bending finite element of triangular shape and associated quadrilateral elements are developed. The transverse displacement is approximated within the element by a quintic polynomial. The formulation takes into account the effects of transverse shear deformation. Results of the static and dynamic analysis of a square plate, with edges simply supported or clamped, are compared with exact solutions. Good accuracy is obtained in all calculations.

  2. Fiber-optic bending sensor for cochlear implantation

    NASA Astrophysics Data System (ADS)

    Li, Enbang; Yao, Jianquan

    2006-09-01

    Cochlear implantation has been proved as a great success in treating profound sensorineural deafness in both children and adults. Cochlear electrode array implantation is a complex and delicate surgical process. Surgically induced damage to the inner wall of the scala tympani could happen if the insertion angle of the electrode is incorrect and an excessive insertion force is applied to the electrode. This damage could lead to severe degeneration of the remaining neural elements. It is therefore of vital importance to monitor the shape and position of the electrode during the implantation surgery. In this paper, we report a fiber-optic bending sensor which can be integrated with the electrode and used to guide the implantation process. The sensor consists of a piece of optical fiber. The end of the fiber is coated with aluminum layer to form a mirror. Bending the fiber with the electrode introduces loss to the light transmitting in the fiber. By detecting the power of the reflected light, we can detennine the bending happened to the fiber, and consequently measure the curved shape of the electrode. Experimental results show that the proposed fiber sensor is a promising technique to make in-situ monitoring of the shape and position of the electrode during the implantation process.

  3. Orbiter Gap Filler Bending Model for Re-entry

    NASA Technical Reports Server (NTRS)

    Campbell, Charles H.

    2007-01-01

    Pressure loads on a protruding gap filler during an Orbiter reentry are investigated to evaluate the likelihood of extraction due to pressure loads, and to ascertain how much bending will be induced by re-entry pressure loads. Oblique shock wave theory is utilized to develop a representation of the pressure loads induced on a gap filler for the ISSHVFW trajectory, representative of a heavy weight ISS return. A free body diagram is utilized to react the forces induced by the pressure forces. Preliminary results developed using these methods demonstrate that pressure loads, alone, are not likely causes of gap filler extraction during reentry. Assessment of the amount a gap filler will bend over is presented. Implications of gap filler bending during re-entry include possible mitigation of early boundary layer transition concerns, uncertainty in ground based measurement of protruding gap fillers from historical Orbiter flight history, and uncertainty in the use of Orbiter gap fillers for boundary layer prediction calibration. Authors will be added to the author list as appropriate.

  4. Optimal Recursive Digital Filters for Active Bending Stabilization

    NASA Technical Reports Server (NTRS)

    Orr, Jeb S.

    2013-01-01

    In the design of flight control systems for large flexible boosters, it is common practice to utilize active feedback control of the first lateral structural bending mode so as to suppress transients and reduce gust loading. Typically, active stabilization or phase stabilization is achieved by carefully shaping the loop transfer function in the frequency domain via the use of compensating filters combined with the frequency response characteristics of the nozzle/actuator system. In this paper we present a new approach for parameterizing and determining optimal low-order recursive linear digital filters so as to satisfy phase shaping constraints for bending and sloshing dynamics while simultaneously maximizing attenuation in other frequency bands of interest, e.g. near higher frequency parasitic structural modes. By parameterizing the filter directly in the z-plane with certain restrictions, the search space of candidate filter designs that satisfy the constraints is restricted to stable, minimum phase recursive low-pass filters with well-conditioned coefficients. Combined with optimal output feedback blending from multiple rate gyros, the present approach enables rapid and robust parametrization of autopilot bending filters to attain flight control performance objectives. Numerical results are presented that illustrate the application of the present technique to the development of rate gyro filters for an exploration-class multi-engined space launch vehicle.

  5. On-line fuzzy logic control of tube bending

    NASA Astrophysics Data System (ADS)

    Lieh, Junghsen; Li, Wei Jie

    2005-11-01

    This paper describes the simulation and on-line fuzzy logic control of tube bending. By combining elasticity and plasticity theories, a conventional model was developed. The results from simulation were compared with those obtained from testing. The experimental data reveal that there exists certain level of uncertainty and nonlinearity in tube bending, and its variation could be significant. To overcome this, a on-line fuzzy logic controller with self-tuning capabilities was designed. The advantages of this on-line system are (1) its computational requirement is simple in comparison with more algorithmic-based controllers, and (2) the system does not need prior knowledge of material characteristics. The device includes an AC motor, a servo controller, a forming mechanism, a 3D optical sensor, and a microprocessor. This automated bending machine adopts primary and secondary errors between the actual response and desired output to conduct on-line rule reasoning. Results from testing show that the spring back angle can be effectively compensated by the self- tuning fuzzy system in a real-time fashion.

  6. Biomorphodynamic modelling of inner bank advance in migrating meander bends

    NASA Astrophysics Data System (ADS)

    Zen, Simone; Zolezzi, Guido; Toffolon, Marco; Gurnell, Angela M.

    2016-07-01

    We propose a bio-morphodynamic model at bend cross-sectional scale for the lateral migration of river meander bends, where the two banks can migrate separately as a result of the mutual interaction between river flow, sediments and riparian vegetation, particularly at the interface between the permanently wet channel and the advancing floodplain. The model combines a non-linear analytical model for the morphodynamic evolution of the channel bed, a quasi-1D model to account for flow unsteadiness, and an ecological model describing riparian vegetation dynamics. Simplified closures are included to estimate the feedbacks among vegetation, hydrodynamics and sediment transport, which affect the morphology of the river-floodplain system. Model tests reveal the fundamental role of riparian plants in generating bio-morphological patterns at the advancing floodplain margin. Importantly, they provide insight into the biophysical controls of the 'bar push' mechanism and into its role in the lateral migration of meander bends and in the temporal variations of the active channel width.

  7. How two-dimensional bending can extraordinarily stiffen thin sheets.

    PubMed

    Pini, V; Ruz, J J; Kosaka, P M; Malvar, O; Calleja, M; Tamayo, J

    2016-01-01

    Curved thin sheets are ubiquitously found in nature and manmade structures from macro- to nanoscale. Within the framework of classical thin plate theory, the stiffness of thin sheets is independent of its bending state for small deflections. This assumption, however, goes against intuition. Simple experiments with a cantilever sheet made of paper show that the cantilever stiffness largely increases with small amounts of transversal curvature. We here demonstrate by using simple geometric arguments that thin sheets subject to two-dimensional bending necessarily develop internal stresses. The coupling between the internal stresses and the bending moments can increase the stiffness of the plate by several times. We develop a theory that describes the stiffness of curved thin sheets with simple equations in terms of the longitudinal and transversal curvatures. The theory predicts experimental results with a macroscopic cantilever sheet as well as numerical simulations by the finite element method. The results shed new light on plant and insect wing biomechanics and provide an easy route to engineer micro- and nanomechanical structures based on thin materials with extraordinary stiffness tunability. PMID:27403938

  8. How two-dimensional bending can extraordinarily stiffen thin sheets

    PubMed Central

    Pini, V.; Ruz, J. J.; Kosaka, P. M.; Malvar, O.; Calleja, M.; Tamayo, J.

    2016-01-01

    Curved thin sheets are ubiquitously found in nature and manmade structures from macro- to nanoscale. Within the framework of classical thin plate theory, the stiffness of thin sheets is independent of its bending state for small deflections. This assumption, however, goes against intuition. Simple experiments with a cantilever sheet made of paper show that the cantilever stiffness largely increases with small amounts of transversal curvature. We here demonstrate by using simple geometric arguments that thin sheets subject to two-dimensional bending necessarily develop internal stresses. The coupling between the internal stresses and the bending moments can increase the stiffness of the plate by several times. We develop a theory that describes the stiffness of curved thin sheets with simple equations in terms of the longitudinal and transversal curvatures. The theory predicts experimental results with a macroscopic cantilever sheet as well as numerical simulations by the finite element method. The results shed new light on plant and insect wing biomechanics and provide an easy route to engineer micro- and nanomechanical structures based on thin materials with extraordinary stiffness tunability. PMID:27403938

  9. The Application of Guided Wave Travel Time Tomography to Bends

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Luiten, Erik; Bloom, Joost

    2010-02-01

    The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. The method should be capable of providing quantitative wall thickness information for both straight pipes and bends. The wave propagation in bends is far more complicated than in straight pipes because natural focusing occurs due to geometrical path differences. Numerical simulations clearly show this effect. Travel time tomography requires accurate modeling of travel times that can be translated to spatial wall thickness variations. Therefore, a ray tracing algorithm has been developed to calculate travel times as part of the tomographic inversion kernel. Numerical results show that a tomographic inversion on simple simulated data provides accurate results. The focusing effect due to the shape of the bend yields a phase rotation of the wavelet, which complicates accurate timing picking. This effect was excluded in the simulated ray tracing data. Based on these observations it is concluded that a more accurate, wave equation based forward modeling algorithm is required to obtain accurate inversion results on realistic data.

  10. Traveling wave type ultrasonic linear motor using twin bending bars

    NASA Astrophysics Data System (ADS)

    Kondo, Shuichi; Yamaura, Hiroshi; Koyama, Daisuke; Nakamura, Kentaro

    2010-01-01

    Ultrasonic linear motors with a small body are highly demanded since efficiency does not decrease very much with downsizing. In this study, we aim at realizing ultrasonic linear motor with the diameter less than 10 mm as an alternative to small air cylinder actuators. We propose a new stator structure using two PZT elements between two parallel bending bars. The PZT elements are bonded at the position of several mm from the bar end. In this structure, both bar ends vibrate resonantly in a bending mode, and high vibration displacement amplitude can be obtained along the bars. The length between the PZT element and the bar end determines the optimum driving frequency. The slider simply consists of three metal plates, which sandwich the bending bars, and the preload can be controlled by springs. The conditions in which the traveling wave can be generated along the bars were investigated. When the bars vibrate in a symmetric mode and traveling waves are generated, the slider moves in the direction to the opposite of traveling wave. Traveling wave could be generated by controlling the driving phase difference between the two PZT elements. It was found that the phase differences depend on the distance between the two PZT elements. We experimentally achieved the stroke of 10 mm and the thrust of 78 mN at 23 kHz.

  11. Bending-induced Symmetry Breaking of Lithiation in Germanium Nanowires

    SciTech Connect

    Gu, Meng; Yang, Hui; Perea, Daniel E.; Zhang, Jiguang; Zhang, Sulin; Wang, Chong M.

    2014-08-01

    From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on one hand lithiation-generated stress mediates lithiation kinetics, and on the other electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion.

  12. Stretching and Bending Fluctuations of Short DNA Molecules

    PubMed Central

    Padinhateeri, Ranjith; Menon, Gautam I.

    2013-01-01

    Recent measurements of the distribution of end-to-end distance in short DNA molecules infer cooperative stretching fluctuations. The assumptions underlying the analysis can be questioned if transient, thermally induced defects producing a localized decrease in bending stiffness are present in thermal equilibrium, such as regions in which DNA melts locally (bubbles), sustains large-angle bends (kinks), or can locally transform into an alternative (S-DNA) state. We study a generalized discrete worm-like chain model for DNA, capable of describing these experiments, showing that the model yields accurate fits to available experimental data. Our results indicate that DNA bending arising from such localized defects, rather than solely stretching, can be an equal contributor to end-to-end distance fluctuations for 35-bp DNA and contributes nontrivially to such fluctuations at all scales below the persistence length. The analysis suggests that such fluctuations should exhibit a scale-dependent cooperativity, specifically relevant in determining the behavior of short chains, but which saturates rapidly to a length-independent value for longer DNA, to ensure a consistent physical description of DNA across multiple scales. Our approach provides a minimal, yet accurate, coarse-grained description of DNA at the subpersistence length scales of current experimental interest. PMID:23442868

  13. How a short double-stranded DNA bends

    NASA Astrophysics Data System (ADS)

    Shin, Jaeoh; Lee, O.-Chul; Sung, Wokyung

    2015-04-01

    A recent experiment using fluorescence microscopy showed that double-stranded DNA fragments shorter than 100 base pairs loop with the probabilities higher by the factor of 102-106 than predicted by the worm-like chain (WLC) model [R. Vafabakhsh and T. Ha, Science 337, 1101(2012)]. Furthermore, the looping probabilities were found to be nearly independent of the loop size. The results signify a breakdown of the WLC model for DNA mechanics which works well on long length scales and calls for fundamental understanding for stressed DNA on shorter length scales. We develop an analytical, statistical mechanical model to investigate what emerges to the short DNA under a tight bending. A bending above a critical level initiates nucleation of a thermally induced bubble, which could be trapped for a long time, in contrast to the bubbles in both free and uniformly bent DNAs, which are either transient or unstable. The trapped bubble is none other than the previously hypothesized kink, which releases the bending energy more easily as the contour length decreases. It leads to tremendous enhancement of the cyclization probabilities, in a reasonable agreement with experiment.

  14. Mechanical properties of orthodontic wires in tension, bending, and torsion.

    PubMed

    Drake, S R; Wayne, D M; Powers, J M; Asgar, K

    1982-09-01

    The mechanical properties of three sizes of stainless steel (SS), nickel-titanium (NT), and titanium-molybdenum (TM) orthodontic wires were studied in tension, bending, and torsion. The wires (0.016 inch, 0.017 by 0.025 inch, and 0.019 by 0.025 inch) were tested in the as-received condition. Tensile testing and stiffness testing machines along with a torsional instrument were used. Mean values and standard deviations of properties were computed. The data were analyzed statistically by analysis of variance using a factorial design. Means were ranked by a Tukey interval calculated at the 95 percent level of confidence. In tension, the stainless steel wires had the least maximum elastic strain or springback, whereas the titanium-molybdenum wires had the most. Higher values of springback indicate the capacity for an increased range of activation clinically. In bending and torsion, the stainless steel wires had the least stored energy at a fixed moment, whereas the nickel-titanium wires had the most. Spring rates in bending and torsion, however, were highest for stainless steel wires and lowest for nickel-titanium wires. A titanium-molybdenum teardrop closing loop delivered less than one half the force of a comparable stainless steel loop for similar activations. PMID:6961793

  15. Atomistic modeling of bending properties of oxidized silicon nanowires

    SciTech Connect

    Ilinov, Andrey Kuronen, Antti

    2014-03-14

    In this work, we have modeled a three point bending test of monocrystalline Si nanowires using molecular dynamics simulations in order to investigate their elastic properties. Tested nanowires were about 30 nm in length and had diameters from 5 to 9 nm. To study the influence of a native oxide layer, nanowires were covered with a 1 nm thick silica layer. The bending force was applied by a carbon diamond half-sphere with a 5 nm diameter. The Si-O parametrization for the Tersoff potential was used to describe atomic interactions between Si and O atoms. In order to remove the indentation effect of the diamond half-sphere and to obtain a pure bending behavior, we have also performed a set of simulations with fixed bottoms of the nanowires. Our results show that the oxide layer reduces the nanowire stiffness when compared with a pure Si nanowire with the same number of silicon atoms—in spite of the fact that the oxidized nanowires had larger diameters.

  16. How two-dimensional bending can extraordinarily stiffen thin sheets

    NASA Astrophysics Data System (ADS)

    Pini, V.; Ruz, J. J.; Kosaka, P. M.; Malvar, O.; Calleja, M.; Tamayo, J.

    2016-07-01

    Curved thin sheets are ubiquitously found in nature and manmade structures from macro- to nanoscale. Within the framework of classical thin plate theory, the stiffness of thin sheets is independent of its bending state for small deflections. This assumption, however, goes against intuition. Simple experiments with a cantilever sheet made of paper show that the cantilever stiffness largely increases with small amounts of transversal curvature. We here demonstrate by using simple geometric arguments that thin sheets subject to two-dimensional bending necessarily develop internal stresses. The coupling between the internal stresses and the bending moments can increase the stiffness of the plate by several times. We develop a theory that describes the stiffness of curved thin sheets with simple equations in terms of the longitudinal and transversal curvatures. The theory predicts experimental results with a macroscopic cantilever sheet as well as numerical simulations by the finite element method. The results shed new light on plant and insect wing biomechanics and provide an easy route to engineer micro- and nanomechanical structures based on thin materials with extraordinary stiffness tunability.

  17. Ethnic Differences in Bending Stiffness of the Ulna and Tibia

    NASA Technical Reports Server (NTRS)

    Arnaud, S. B.; Liang, M. T. C.; Bassin, S.; Braun, W.; Dutto, D.; Plesums, K.; Huvnh, H. T.; Cooper, D.; Wong, N.

    2004-01-01

    There is considerable information about the variations in bone mass associated with different opportunity to compare a mechanical property of bone in young college women of Caucasian, Hispanic and Asian descent who gave informed consent to participate in an exercise study. The subjects were sedentary, in good health, eumenorrheic, non-smokers and had body mass indices (BMI) less than 30. Measurements acquired were body weight, kg, and height, cm, calcaneal and wrist bone density, g/square cm (PIXI, Lunar GE) and bending stiffness (EI, Nm(exp 2)) in the ulna and tibia. E1 was determined non-invasively with an instrument called the Mechanical Response Tissue Analyzer (MRTA) that delivers a vibratory stimulus to the center of the ulna or tibia and analyzes the response curve based on the equation E1 = k(sub b) L(exp 3)/48 where k, is lateral bending stiffness, L is the length of the bone, E is Young's modulus of elasticity and I, the bending moment of inertia. The error of the test (CV) based on measurements of an aluminum rod with a known E1 was 4.8%, of calcaneal BMD, 0.54%, and of wrist bone density, 3.45%.

  18. An optical fiber weighing sensor based on bending

    NASA Astrophysics Data System (ADS)

    Vijayan, Anu; Gawli, Sarika; Kulkarni, Atul; Karekar, R. N.; Aiyer, R. C.

    2008-10-01

    The bending of plastic optical fiber (POF) is used to develop a weighing sensor by fully gluing POF onto a strip of spring steel used as a clamped beam for sensing, keeping the glued fiber either on the top or bottom side of the beam. Force, in the form of weight, is applied to the beam in two ways: by attaching a pan (i) at one of the ends of the beam or (ii) at the center of the beam, with proper clamping. The known weight is added in the pan for calibration purposes. The output light intensity of the fiber, measured as voltage, changes practically linearly with increasing weight up to a certain limit due to the macrobending of POF. It is found that though elongative bending decreases the output intensity, compressive bending gives a reverse effect. The response time for sensing is found to be approximately 5-7 s with larger recovery time (<=1 min). No noticeable hysteresis is observed. The thickness and length of the beam are varied and optimized. The sensor specifications can be tailored by this to some extent. A minimum weight of 5 g and a maximum of ~1900 g could be measured in a linear range for the beam-length used.

  19. Lateral bending of the lumbar spine during quadrupedalism in strepsirhines.

    PubMed

    Shapiro, L J; Demes, B; Cooper, J

    2001-03-01

    Much research has been devoted to spinal kinematics of nonmammalian vertebrates, while comparatively little is known about the locomotor role of spinal movements in mammals, especially primates. This study, conducted at the Duke University Primate Center, examines the function of lateral spinal bending during quadrupedal walking among a diverse sample of strepsirhines. The taxa studied include Loris tardigradus (1), Nycticebus coucang (1), N. pygmaeus (1), Cheirogaleus medius (2), Varecia variegata (2), Eulemur fulvus (2), and a total sample size of 261 strides. Lateral bending varies among the taxa with respect to both magnitude and effects of velocity, and does not appear to be correlated with body size. In addition, the timing of lateral bending during a stride appears to differ from that reported for other (nonmammalian) tetrapods. On average, maximum lateral flexion occurs just after ipsilateral foot touchdown, which may be functionally associated with touchdown of the contralateral forelimb during diagonal sequence gait. For some of the taxa, lateral flexion coincides more closely with foot touchdown as velocity increases, suggesting a functional role in increasing hindlimb stride length. Both of these timing patterns contrast with those reported for lizards. Finally, although lorids as a group have been described as having a "sinuous" gait, this study shows more pronounced lateral flexion in Nycticebus than in Loris. PMID:11180987

  20. Four point bending setup for characterization of semiconductor piezoresistance.

    PubMed

    Richter, J; Arnoldus, M B; Hansen, O; Thomsen, E V

    2008-04-01

    We present a four point bending setup suitable for high precision characterization of piezoresistance in semiconductors. The compact setup has a total size of 635 cm(3). Thermal stability is ensured by an aluminum housing wherein the actual four point bending fixture is located. The four point bending fixture is manufactured in polyetheretherketon and a dedicated silicon chip with embedded piezoresistors fits in the fixture. The fixture is actuated by a microstepper actuator and a high sensitivity force sensor measures the applied force on the fixture and chip. The setup includes heaters embedded in the housing and controlled by a thermocouple feedback loop to ensure characterization at different temperature settings. We present three-dimensional finite element modeling simulations of the fixture and discuss the possible contributions to the uncertainty of the piezoresistance characterization. As a proof of concept, we show measurements of the piezocoefficient pi(44) in p-type silicon at three different doping concentrations in the temperature range from T=30 degrees C to T=80 degrees C. The extracted piezocoefficients are determined with an uncertainty of 1.8%. PMID:18447540

  1. Measuring the bending of asymmetric planar EAP structures

    NASA Astrophysics Data System (ADS)

    Weiss, Florian M.; Zhao, Xue; Thalmann, Peter; Deyhle, Hans; Urwyler, Prabitha; Kovacs, Gabor; Müller, Bert

    2013-04-01

    The geometric characterization of low-voltage dielectric electro-active polymer (EAP) structures, comprised of nanometer thickness but areas of square centimeters, for applications such as artificial sphincters requires methods with nanometer precision. Direct optical detection is usually restricted to sub-micrometer resolution because of the wavelength of the light applied. Therefore, we propose to take advantage of the cantilever bending system with optical readout revealing a sub-micrometer resolution at the deflection of the free end. It is demonstrated that this approach allows us to detect bending of rather conventional planar asymmetric, dielectric EAP-structures applying voltages well below 10 V. For this purpose, we built 100 μm-thin silicone films between 50 nm-thin silver layers on a 25 μm-thin polyetheretherketone (PEEK) substrate. The increase of the applied voltage in steps of 50 V until 1 kV resulted in a cantilever bending that exhibits only in restricted ranges the expected square dependence. The mean laser beam displacement on the detector corresponded to 6 nm per volt. The apparatus will therefore become a powerful mean to analyze and thereby improve low-voltage dielectric EAP-structures to realize nanometer-thin layers for stack actuators to be incorporated into artificial sphincter systems for treating severe urinary and fecal incontinence.

  2. Magnetic measurements of the correction and adjustment magnets of the main ring

    SciTech Connect

    Trbojevic, D.

    1986-07-01

    Correction magnets correct the field imperfections and alignment errors of the main quadrupole and bend magnets. For reducing and controlling chromaticity there are 186 sextupoles and 78 octupoles, while for suppressing various resonances there are 12 normal and 18 skew sextupoles and 24 normal and 19 skew quadrupoles. Beam positions are individually controlled by 108 horizontal and 108 skew dipoles. This report includes results of the all Main Ring correction and adjustment magnet harmonic measurements. The measurement principle and basic equations are described.

  3. Magnetic flux circulation in the rotationally-driven giant magnetospheres

    NASA Astrophysics Data System (ADS)

    Delamere, P. A.; Otto, A.; Ma, X.; Bagenal, F.; Wilson, R. J.

    2014-12-01

    The giant planet magnetodiscs are shaped by the radial transport of plasma originating in the inner magnetosphere. Along with plasma transport, magnetic flux transport is a key aspect of the stretched magnetic field configuration of the magnetodisc. While net mass transport is outward (ultimately lost to the solar wind), magnetic flux conservation requires a balanced two-way transport process involving magnetic reconnection. A key property of flux transport is the azimuthal bend forward or bend back of the magnetic field. The bend back configuration is an expected property of the magnetodisc with net mass outflow, but the bend forward configuration can be achieved with the rapid inward motion of mostly empty flux tubes following thin current sheet reconnection. We present a comprehensive analysis of current sheet crossings in Saturn's magnetosphere using Cassini MAG data from 2004 to 2012 in an attempt to quantify the circulation of magnetic flux, emphasizing local time dependence. We find that the bend forward cases are limited mostly to the post-noon sector, indicating that much of the reconnection returning flux to the inner magnetosphere occurs in the subsolar and dusk sector. We also find a complex and patchy network of reconnection sites, supporting the idea that plasma can be lost on small-scales through a ``drizzle''-like process rather than a single extended X-line as originally envisioned for the Vasyliunas cycle. Auroral implications for the observed flux circulation and comparisons with Jupiter will also be presented.

  4. In situ transmission electron microscopy of individual carbon nanotetrahedron/ribbon structures in bending

    SciTech Connect

    Kohno, Hideo; Masuda, Yusuke

    2015-05-11

    When the direction of flattening of a carbon nanotube changes during growth mediated by a metal nanoparticle, a carbon nanotetrahedron is formed in the middle of the carbon nanoribbon. We report the bending properties of the carbon nanotetrahedron/nanoribbon structure using a micro-manipulator system in a transmission electron microscope. In many cases, bending occurs at an edge of the carbon nanotetrahedron. No significant change is observed in the tetrahedron's shape during bending, and the bending is reversible and repeatable. Our results show that the carbon nanotetrahedron/nanoribbon structure has good durability against mechanical bending.

  5. Studies on the influence of axial bends on ultrasonic guided waves in hollow cylinders (pipes)

    NASA Astrophysics Data System (ADS)

    Verma, Bhupesh; Balasubramaniam, Krishnan; Rajagopal, Prabhu

    2013-01-01

    Ultrasonic guided waves in hollow cylinders (pipes) are today widely applied as rapid screening tools in the inspection of straight pipe segments in oil, power generation and petrochemical processing industries. However, the characteristics of guided wave propagation across features such as bends in the pipe network are complicated, hampering a wider application of the developed techniques. Although a growing number of studies in recent years have considered guided wave propagation across elbows and U-type bends, the topic is still not very well understood for a general bend angle φ, mean bend radius R and pipe thickness b. Here we use 3D Finite Element (FE) simulation to illumine the propagation of fundamental guided pipe modes across bends of several different angles φ. Two different bend radius regimes, R/λ ≈ 1 and 10 (where λ denotes the wavelength of the mode studied) are considered, exemplifying 'sharp' and gradual or 'slow' bends. Different typical pipe thicknesses b within these regimes are also studied. The results confirm the expectation that different bend radius regimes affect the waves differently. Further, while as observed in earlier studies, at moderate bend radii, fundamental modes travel almost unaffected by an elbow (bend angle φ = 90 degrees), we find that as the bend angle is reduced, there is a progressively larger extent of mode-conversion. These trends and results are validated using experiments.

  6. Design and Simulation Results of Waveguide Bends Used in Debuncher Cooling System

    SciTech Connect

    Sun, Ding; /Fermilab

    2000-09-13

    This note is a document about design and simulation results of waveguide bends installed with the arrays in debuncher cooling upgrade. The main feature of these bends is that they are not traditional mitered bends or round bends. Instead, a cylinder is placed in the corner area of the bend. The reason for this design is purely to overcome some practical problems: (1) since these bends are very close to the slotted foil which serves as part of the waveguide array, it is very difficult to make good joint and contact if mitered bends are used, (2) assembly difficulty due to the location of these bends, and (3) limited space requires a compact design. Shown in Figure 1 is a schematic drawing of a bend. Dimensions of bends for each frequency band are listed in Table 1. Shown in Figure 2-5 are the simulation results using HFSS. One of the bends was fabricated with flanges on both ends and measured using a Network Analyzer. The HFSS result was confirmed by the measured data.

  7. Experimental investigations and statistical analysis of pulsed laser bending of AISI 304 stainless steel sheet

    NASA Astrophysics Data System (ADS)

    Maji, Kuntal; Pratihar, D. K.; Nath, A. K.

    2013-07-01

    This paper presents experimental investigations on pulsed laser bending of sheet metal and statistical analysis to study the effects of process parameters. Laser power, scan speed, spot diameter and pulsed duration were taken as input variables and bending angle was considered as the output. Response surface methodology was used for modeling and optimization of the pulsed laser bending process. The performance of the developed model was validated through the experiments. All the input variables were found to have significant influence on the bending angle. Bending angle increased with the increase of laser power and pulse duration and decreased with the increase of scan speed and spot diameter. The optimum process parameters for the maximum bending angle were also found and verified with experimental data. The effects of pulse frequency, pulse width and pulse energy on bending angle were also investigated through experiments. Bending angle was found to be the maximum for a certain value of pulse frequency. With the increase of pulse width, bending angle increased at constant laser power but decreased at constant pulse energy. Bending angle was seen to increase with the increase of spatial overlapping and decrease with the increase of gap at constant laser power, but it showed optimal values for both the cases at constant line energy. A comparative study between continuous and pulsed laser bending was carried out to study the process efficiency in terms of energy input and produced deformation.

  8. The influence of bending strains on AC power losses in multifilamentary BSCCO-2223/Ag tapes

    NASA Astrophysics Data System (ADS)

    Tsukamoto, O.; Ciszek, M.; Suzuki, H.; Ogawa, J.

    2006-08-01

    Recent advances in the manufacturing of multifilamentary high temperature superconducting composite wires allow for wider practical applications of the conductors, e.g. in power transmission cables, transformers and motors. The wires, based mainly on BSCCO-2223 and YBCO-123 cuprates, are used in the forms of variously shaped coils; therefore they are subjected to different kinds of mechanical stresses and strains. These, in turn, lead to some changes in the physical parameters of the superconducting material, mainly in the critical current density, and thus in the dissipated electromagnetic energy, when subjected to changing magnetic fields and transport currents. In this work we report some experimental results related to the AC loss characteristics of Bi-2223/Ag multifilamentary tapes and their dependences on bending strains. These losses are compared to the losses of virgin, straight tapes. The total AC losses, i.e. transport current and magnetization losses, in the Bi-2223/Ag tapes, were measured by means of the electrical and calorimetric methods. The experimental data obtained are compared with the critical state model predictions for AC loss behaviour in the experimental conditions presented here.

  9. Accurate Determination of Torsion and Pure Bending Moment for Viscoelastic Measurements

    NASA Astrophysics Data System (ADS)

    Wang, Yun-Che; Ko, Chih-Chin; Shiau, Li-Ming

    Measurements of time-dependent material properties in the context of linear viscoelasticity, at a given frequency and temperature, require accurate determination of both loading and deformation that are subjected to the testing materials. A pendulum-type viscoelastic spectroscopy is developed to experimentally measure loss tangent and the magnitude of dynamic modulus of solid materials. The mechanical system of the device is based on the behavior of the cantilever beam, and torsion and pure bending moment are generated from the interaction between a permanent magnet and the Helmholtz coils. The strength of the magnetic interactions may be determined with a material with known mechanical properties, such as aluminum 6061T4 alloy. The sensitivity of the torque measurement is on the order of one micro N-m level. With the high accurate torque measurement and deformation detection from a laser-based displacement measurement system, viscoelastic properties of materials can be experimentally measured in different frequency regimes. Sinusoidal driving signals are adopted for measuring complex modulus in the sub-resonant regime, and dc bias driving for creep tests in the low frequency limit. At structural resonant frequencies, the full-width-at-half-maximum (FWHM) method or Lorentzian curve fitting method is adopted to extract material properties. The completion of determining material properties in the wide frequency spectrum may help to identify the deformation mechanisms of the material and to create better models for simulation work.

  10. Charge and Strain Control of Interface Magnetism

    NASA Astrophysics Data System (ADS)

    Fitzsimmons, M. R.; Dumesnil, K.; Jaouen, N.; Maroutian, T.; Agnus, G.; Tonnerre, J.-M.; Kirby, B.; Fohtung, E.; Holladay, B.; Fullerton, E. E.; Shpyrko, O.; Sinha, S. K.; Wang, Q.; Chen, A.; Jia, Q. X.

    2015-03-01

    We studied the influence of an electric field applied to an La0.67Sr0.33MnO3 (LSMO) layer in a LSMO/Pb(Zr0.2Ti0.8) O3 (PZT)/Nb-doped SrTiO3 (STO) heterostructure by measuring its magnetization depth profile using resonant x-ray magnetic reflectivity. The saturation magnetization of the ferromagnetically-ordered LSMO was not affected by the direction of the polarization of the PZT. However, the ferromagnetic thickness and magnetization of the LSMO film at remanence were reduced for hole-charge accumulation at the LSMO/PZT interface. To understand the independent roles of strain and hole-doping, we performed neutron scattering experiments of La0.8Sr0.2MnO3 films grown on Nb-doped STO in which bending strain (via 4-point bending jig) or electric field (via parallel plate capacitor) was applied to the films. We observed that bending strain affects the saturation magnetization of the LSMO film, whereas electric field affects the remanent magnetization of the film. These observations suggest strain may be a more effective means to control magnetism than charge. This work has benefited from use of CINT(LANL), NIST Center for Neutron Research and the Synchrotron SOLEIL and funding from LANL/LDRD program, DOE-BES (UCSD) and DOD (NMSU).

  11. Composite Bending Box Section Modal Vibration Fault Detection

    NASA Technical Reports Server (NTRS)

    Werlink, Rudy

    2002-01-01

    One of the primary concerns with Composite construction in critical structures such as wings and stabilizers is that hidden faults and cracks can develop operationally. In the real world, catastrophic sudden failure can result from these undetected faults in composite structures. Vibration data incorporating a broad frequency modal approach, could detect significant changes prior to failure. The purpose of this report is to investigate the usefulness of frequency mode testing before and after bending and torsion loading on a composite bending Box Test section. This test article is representative of construction techniques being developed for the recent NASA Blended Wing Body Low Speed Vehicle Project. The Box section represents the construction technique on the proposed blended wing aircraft. Modal testing using an impact hammer provides an frequency fingerprint before and after bending and torsional loading. If a significant structural discontinuity develops, the vibration response is expected to change. The limitations of the data will be evaluated for future use as a non-destructive in-situ method of assessing hidden damage in similarly constructed composite wing assemblies. Modal vibration fault detection sensitivity to band-width, location and axis will be investigated. Do the sensor accelerometers need to be near the fault and or in the same axis? The response data used in this report was recorded at 17 locations using tri-axial accelerometers. The modal tests were conducted following 5 independent loading conditions before load to failure and 2 following load to failure over a period of 6 weeks. Redundant data was used to minimize effects from uncontrolled variables which could lead to incorrect interpretations. It will be shown that vibrational modes detected failure at many locations when skin de-bonding failures occurred near the center section. Important considerations are the axis selected and frequency range.

  12. Bending strength and holding power of tibial locking screws.

    PubMed

    Lin, J; Lin, S J; Chiang, H; Hou, S M

    2001-04-01

    The bending strength and holding power of two types of specially designed tibial locking devices, a both-ends-threaded screw and an unthreaded bolt, were studied and compared with four types of commercially available tibial interlocking screws: Synthes, Howmedica, Richards, and Osteo AG. To test bending strength, the devices were inserted into a high molecular weight polyethylene tube and loaded at their midpoint by a materials testing machine to simulate a three point bending test. Single loading yielding strength and cyclic loading fatigue life were measured. To test holding power, the devices were inserted into tubes made of polyurethane foam, and their tips were loaded axially to measure pushout strength. The devices were tested with two different densities of foam materials and two different sizes of pilot holes. Insertion torque and stripping torque of the screws were measured first. Pushout tests were performed with each screw inserted with a tightness equal to 60% of its stripping torque. Test results showed that the yielding strength and the fatigue life were related closely to the inner diameter of the screws. The stripping torque predicted the pushout strength more reliably than did the insertion torque. All tested devices showed greater holding power in the foam with the higher density and with the smaller pilot holes. The both-ends-threaded screw had the highest pushout strength and a satisfactory fatigue strength. The unthreaded bolt had the highest fatigue strength but only fair holding power. Clinical studies of the use of these two types of locking devices are worthwhile. PMID:11302315

  13. Reversible Bending Fatigue Testing on Zry-4 Surrogate Rods

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L

    2014-01-01

    Testing high-burnup spent nuclear fuel (SNF) presents many challenges in areas such as specimen preparation, specimen installation, mechanical loading, load control, measurements, data acquisition, and specimen disposal because these tasks are complicated by the radioactivity of the test specimens. Research and comparison studies conducted at Oak Ridge National Laboratory (ORNL) resulted in a new concept in 2010 for a U-frame testing setup on which to perform hot-cell reversible bending fatigue testing. Subsequently, the three-dimensional finite element analysis and the engineering design of components were completed. In 2013 the ORNL team finalized the upgrade of the U-frame testing setup and the integration of the U-frame setup into a Bose dual linear motor test bench to develop a cyclic integrated reversible-bending fatigue tester (CIRFT). A final check was conducted on the CIRFT test system in August 2013, and the CIRFT was installed in the hot cell in September 2013 to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The fatigue responses of Zircaloy-4 (Zry-4) cladding and the role of pellet pellet and pellet clad interactions are critical to SNF vibration integrity, but such data are not available due to the unavailability of an effective testing system. While the deployment of the developed CIRFT test system in a hot cell will provide the opportunity to generate the data, the use of a surrogate rod has proven quite effective in identifying the underlying deformation mechanism of an SNF composite rod under an equivalent loading condition. This paper presents the experimental results of using surrogate rods under CIRFT reversible cyclic loading. Specifically, monotonic and cyclic bending tests were conducted on surrogate rods made of a Zry-4 tube and alumina pellet inserts, both with and without an epoxy bond.

  14. Bending modulus of bidisperse particle rafts: Local and collective contributions

    NASA Astrophysics Data System (ADS)

    Petit, Pauline; Biance, Anne-Laure; Lorenceau, Elise; Planchette, Carole

    2016-04-01

    The bending modulus of air-water interfaces covered by a monolayer of bidisperse particles is probed experimentally under quasistatic conditions via the compression of the monolayer, and under dynamical conditions studying capillary-wave propagation. Simple averaging of the modulus obtained solely with small or large particles fails to describe our data. Indeed, as observed in other configurations for monodisperse systems, bidisperse rafts have both a granular and an elastic character: chain forces and collective effects must be taken into account to fully understand our results.

  15. Experimental Stress Analysis of Stiffened Cylinders with Cutouts : Pure Bending

    NASA Technical Reports Server (NTRS)

    Schlechte, Floyd R; Rosecrans, Richard

    1954-01-01

    Bending tests were made on a cylindrical semimonocoque shell of circular cross section. The cylinder was tested without a cutout and then with a rectangular cutout which was successively enlarged through six sizes varying from 30 degrees to 130 degrees in circumference and from 1 to 2 bays in length. Strain measurements were made with resistance-type wire strain gages near the cutout on the stringers, the skin, and the rings for each size of cutout, and the stresses obtained are presented in tables. (author)

  16. Damping in coupled bending and torsion - An experiment

    NASA Technical Reports Server (NTRS)

    Umland, Jeffrey W.; Inman, Daniel J.; Banks, H. T.

    1991-01-01

    Traditional experimental modal testing methods are used to determine the damping properties of a Euler-Bernoulli beam with offset inertial tip mass. Both viscous and strain rate damping models are considered in bending and in torsion. A partial differential equation model of the coupled system is used. Eigenfunctions are derived for the coupled system by using a Green's function approach to derive the approximate uncoupled eigenfunctions. These eigenfunctions are used in a decoupled fashion with experimental modal data to estimate the damping parameters of the coupled system. The experimental modal data were obtained from both free and impulse responses using a combined translational and rotational accelerometer.

  17. CFD Application to Flow-Accelerated Corrosion in Feeder Bends

    SciTech Connect

    Pietralik, John M.; Smith, Bruce A.W.

    2006-07-01

    Feeder piping in CANDU{sup R} plants experiences a thinning degradation mechanism called Flow-Accelerated Corrosion (FAC). The piping is made of carbon steel and has high water flow speeds. Although the water chemistry is highly alkaline with room-temperature pH in a range of 10.0-10.5, the piping has FAC rates exceeding 0.1 mm/year in some locations, e.g., in bends. One of the most important parameters affecting the FAC rate is the mass transfer coefficient for convective mass transport of ferrous ions. The ions are created at the pipe wall as a result of corrosion, diffuse through the oxide layer, and are transported from the oxide-layer/water interface to the bulk water by mass transport. Consequently, the local flow characteristics contribute to the highly turbulent convective mass transfer. Plant data and laboratory experiments indicate that the mass transfer step dominates FAC under feeder conditions. In this study, the flow and mass transfer in a feeder bend under operating conditions were simulated using the Fluent{sup TM} computer code. Because the flow speed is very high, with the Reynolds numbers in a range of several millions, and because the geometry is complex, experiments in a 1:1 scale were conducted with the main objective to validate flow simulations. The experiments measured pressure at several key locations and visualized the flow. The flow and mass transfer models were validated using available friction-factor and mass transfer correlations and literature experiments on mass transfer in a bend. The validation showed that the turbulence model that best predicts the experiments is the realizable k-{epsilon} model. Other two-equation turbulence models, as well as one-equation models and Reynolds stress models were tried. The near-wall treatment used the non-equilibrium wall functions. The wall functions were modified for surface roughness when necessary. A comparison of the local mass transfer coefficient with measured FAC rate in plant specimens

  18. Wake-induced bending of two-dimensional plasma crystals

    SciTech Connect

    Röcker, T. B. Ivlev, A. V. Zhdanov, S. K.; Morfill, G. E.; Couëdel, L.

    2014-07-15

    It is shown that the wake-mediated interactions between microparticles in a two-dimensional plasma crystal affect the shape of the monolayer, making it non-flat. The equilibrium shape is calculated for various distributions of the particle number density in the monolayer. For typical experimental conditions, the levitation height of particles in the center of the crystal can be noticeably smaller than at the periphery. It is suggested that the effect of wake-induced bending can be utilized in experiments, to deduce important characteristics of the interparticle interaction.

  19. Bending stiffness of conical and standard external fixator pins.

    PubMed

    Oni, O O; Capper, M; Soutis, C

    1993-10-01

    The bending stiffnesses of a conical and a standard external fixator pin have been compared. The pins were inserted into pilot holes in a piece of teak hardwood and loads of different magnitudes were applied at a fixed moment arm. Force-deflection curves were obtained for each pin, and stiffness (newtons per metre) and percentage stiffness reduction were calculated for each pilot hole size. The results show that deflection increased (i.e. stiffness decreased) with increasing force or diameter of pilot hole. This loss of stiffness was linear for the standard pin but was bimodal for the conical pin. PMID:8286671

  20. Determining a bends-preventing pressure for a space suit

    NASA Technical Reports Server (NTRS)

    Krutz, R. W., Jr.; Webb, J. T.; Dixon, G. A.

    1989-01-01

    Research conducted to determine the proper pressure for preventing bends during EVA without preoxygenation is examined. Male and female subjects with different breathing gas mixtures and pressures are studied in order to define the pressure. Visual and auditory Doppler ultrasonic signals are utilized to monitor intravascular gas bubbles. The workload, which simulates EVA, consists of a handturned bicycle ergometer, a torque wrench operation, and a rope pull. The experimental data reveal that the minimum space suit pressure needed to prevent decompression sickness is 9.5 psi.

  1. Numerical fracture simulation of compact and bend specimens

    NASA Astrophysics Data System (ADS)

    Shivakumar, K. N.; Newman, J. C., Jr.

    An elastic-plastic finite-element analysis with a critical crack-tip-opening displacement criterion was used to simulate fracture of various size compact and bend specimens made of HY-130 steel. From the calculated load-crack-extension and load-displacement curves, J-resistance (J-R) curves were determined by several methods. The simulated 3-R curves were insensitive to specimen size up to maximum load but were sensitive to specimen configuration for crack extensions greater than 10 percent of the initial uncracked ligament length.

  2. Numerical fracture simulation of compact and bend specimens

    NASA Technical Reports Server (NTRS)

    Shivakumar, K. N.; Newman, J. C., Jr.

    1988-01-01

    An elastic-plastic finite-element analysis with a critical crack-tip-opening displacement criterion was used to simulate fracture of various size compact and bend specimens made of HY-130 steel. From the calculated load-crack-extension and load-displacement curves, J-resistance (J-R) curves were determined by several methods. The simulated 3-R curves were insensitive to specimen size up to maximum load but were sensitive to specimen configuration for crack extensions greater than 10 percent of the initial uncracked ligament length.

  3. Particle deposition in ventilation ducts: Connectors, bends anddeveloping flow

    SciTech Connect

    Sippola, Mark R.; Nazaroff, William W.

    2004-03-01

    In ventilation duct flow the turbulent flow profile is commonly disturbed or not fully developed and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90{sup o} duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. In the steel duct system, experiments with nominal particle diameters of 1, 3, 5, 9 and 16 {micro}m were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition of particles with nominal diameters of 1, 3, 5, 8 and 13 {micro}m was measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces. Deposition at S-connectors, in bends and in straight ducts with developing turbulence was often greater than deposition in straight ducts with fully developed turbulence for equal particle sizes, air speeds and duct surface orientations. Deposition rates at all locations were found to increase with an increase in particle size or air speed. High deposition rates at S-connectors resulted from impaction and these rates were nearly independent of the orientation of the S-connector. Deposition rates in the two 90{sup o} bends differed by more than an order of magnitude in some cases, probably because of the difference in turbulence conditions at the bend inlets. In straight steel ducts where the turbulent flow profile was developing, the deposition enhancement relative to fully developed turbulence generally increased with air speed and decreased with downstream distance from the duct inlet. This enhancement was greater at the duct ceiling and wall than at the duct floor. In insulated ducts, deposition enhancement was less pronounced overall

  4. Prevention of thermal bending of multilayered beams and plates

    NASA Technical Reports Server (NTRS)

    Yang, J. C. S.

    1975-01-01

    By adding an extra layer to multilayer beams or plates of different isotropic materials, it is possible to prevent the thermal bending of these materials. With the proper selection of thermoelastic properties the curvature produced prior to this addition would be eliminated. Several numerical examples are presented for various temperature distributions. A simple experiment was conducted, involving the addition of a brass strip to a bimetallic strip made of aluminum and steel at room temperature. The trimetal strip was placed in a furnace and remained straight for varying temperatures.

  5. The effect of bending on the stresses in adhesive joints

    NASA Technical Reports Server (NTRS)

    Yuceoglu, U.; Updike, D. P.

    1975-01-01

    The problem of stress distribution in adhesive joints where two orthotropic plates are bonded through a flexible adhesive layer is analyzed. It is shown that the effect of bending of the adherends on the stresses in the adhesive layer is very significant. The transverse shear deformations of the adherends appear to have little influence on the adhesive layer stresses. The maximum transverse normal stress in the adhesive is shown to be larger than the maximum longitudinal shear stress. The method of solution is applied to several examples of specific joint geometries and material combinations, and is proven to be applicable to other related problems.

  6. Geometrical effects of fault bends on fault frictional and mechanical behavior: insights from Distinct Element simulations

    NASA Astrophysics Data System (ADS)

    Guo, Y.; Morgan, J.

    2006-12-01

    Strike slip and transform faults often consist of nonlinear segments, i.e., restraining bends and releasing bends that have significant impacts on stress pattern, strain accumulation, slip rate, and therefore the variation of seismicity along these faults. In order to study the geometrical effects of nonlinear faults on fault frictional and mechanical behavior during fault loading and slip, we simulate the rupture process of faults with bends using the Distinct Element Method (DEM) in 2-dimensions. Breakable elastic bonds were added between adjacent, closely packed circular particles to generate fault blocks. A nonlinear fault surface with a restraining bend and a releasing bend that are symmetrically distributed was defined in the middle of the fault blocks. Deformation was introduced by pulling a spring attached on one of fault zone boundaries at a constant velocity and keeping another boundary fixed, producing compression and contraction along the restraining bend, and tension and dilation along the releasing bend. Significant strain is accommodated adjacent to the restraining bend by formation of secondary faults and slip along them. The slip rates, fault frictional strengths, and rupture processes are affected by multiple parameters, including bond strength, loading velocity, bend angle and amplitude. Among these parameters, bend geometry plays a more important role in determining spatial and temporal distribution of contact slip and failure of our simulated nonlinear faults.

  7. Evaluation of spinal instrumentation rod bending characteristics for in-situ contouring.

    PubMed

    Noshchenko, Andriy; Xianfeng, Yao; Armour, Grant Alan; Baldini, Todd; Patel, Vikas V; Ayers, Reed; Burger, Evalina

    2011-07-01

    Bending characteristics were studied in rods used for spinal instrumentation at in-situ contouring conditions. Five groups of five 6 mm diameter rods made from: cobalt alloy (VITALLIUM), titanium-aluminum-vanadium alloy (SDI™), β-titanium alloy (TNTZ), cold worked stainless steel (STIFF), and annealed stainless steel (MALLEABLE) were studied. The bending procedure was similar to that typically applied for in-situ contouring in the operating room and included two bending cycles: first--bending to 21-24° under load with further release of loading for 10 min, and second--bending to 34-37° at the previously bent site and release of load for 10 min. Applied load, bending stiffness, and springback effect were studied. Statistical evaluation included ANOVA, correlation and regression analysis. TNTZ and SDI™ rods showed the highest (p < 0.05) springback at both bending cycles. VITALLIUM and STIFF rods showed mild springback (p < 0.05). The least (p < 0.05) springback was observed in the MALLEABLE rods. Springback significantly correlated with the bend angle under load (p < 0.001). To reach the necessary bend angle after unloading, over bending should be 37-40% of the required angle in TNTZ and SDI™ rods, 27-30% in VITALLIUM and STIFF rods, and around 20% in MALLEABLE rods. PMID:21563305

  8. Bend insensitive graded index multimode polymer optical waveguides fabricated using the Mosquito method

    NASA Astrophysics Data System (ADS)

    Takahashi, Asami; Ishigure, Takaaki

    2015-02-01

    We fabricate low-loss graded index (GI) circular core multimode polymer optical waveguides with 90o bending and demonstrate low bending loss even if the bend radius is as small as 1 mm. In the several fabrication methods for GI-core polymer waveguides already proposed, we adopt the "Mosquito method" that utilize a microdispenser because the Mosquito method makes it possible to fabricate waveguides directly on board at desired places on a printed circuit board, and to draw various patterns of cores including curves. However, in the waveguides including such curved cores, the additional transmission loss due to the bending (bending loss) is a concern. Thus, we characterize the fabricated GI-core polymer waveguides with bending: using two kinds of cladding monomer with different refractive indexes for fabricating waveguides with bending. We found when the NA of waveguides was as high as 0.35, no additional loss due to bending was observed even if the bending radius is as small as 1 mm. The core diameter of the fabricated waveguides is 50 μm, and it is possible to further decrease the bending loss in the waveguides with smaller core diameter. Furthermore, utilizing the Mosquito method, we fabricate waveguides with not only horizontally curved cores but also vertically curved ones. Waveguides with vertically curved cores could make it possible to realize three-dimensionally optical wiring applicable to on-board optical interconnects.

  9. A Novel Low-Cost, Large Curvature Bend Sensor Based on a Bowden-Cable

    PubMed Central

    Jeong, Useok; Cho, Kyu-Jin

    2016-01-01

    Bend sensors have been developed based on conductive ink, optical fiber, and electronic textiles. Each type has advantages and disadvantages in terms of performance, ease of use, and cost. This study proposes a new and low-cost bend sensor that can measure a wide range of accumulated bend angles with large curvatures. This bend sensor utilizes a Bowden-cable, which consists of a coil sheath and an inner wire. Displacement changes of the Bowden-cable’s inner wire, when the shape of the sheath changes, have been considered to be a position error in previous studies. However, this study takes advantage of this position error to detect the bend angle of the sheath. The bend angle of the sensor can be calculated from the displacement measurement of the sensing wire using a Hall-effect sensor or a potentiometer. Simulations and experiments have shown that the accumulated bend angle of the sensor is linearly related to the sensor signal, with an R-square value up to 0.9969 and a root mean square error of 2% of the full sensing range. The proposed sensor is not affected by a bend curvature of up to 80.0 m−1, unlike previous bend sensors. The proposed sensor is expected to be useful for various applications, including motion capture devices, wearable robots, surgical devices, or generally any device that requires an affordable and low-cost bend sensor. PMID:27347959

  10. A Novel Low-Cost, Large Curvature Bend Sensor Based on a Bowden-Cable.

    PubMed

    Jeong, Useok; Cho, Kyu-Jin

    2016-01-01

    Bend sensors have been developed based on conductive ink, optical fiber, and electronic textiles. Each type has advantages and disadvantages in terms of performance, ease of use, and cost. This study proposes a new and low-cost bend sensor that can measure a wide range of accumulated bend angles with large curvatures. This bend sensor utilizes a Bowden-cable, which consists of a coil sheath and an inner wire. Displacement changes of the Bowden-cable's inner wire, when the shape of the sheath changes, have been considered to be a position error in previous studies. However, this study takes advantage of this position error to detect the bend angle of the sheath. The bend angle of the sensor can be calculated from the displacement measurement of the sensing wire using a Hall-effect sensor or a potentiometer. Simulations and experiments have shown that the accumulated bend angle of the sensor is linearly related to the sensor signal, with an R-square value up to 0.9969 and a root mean square error of 2% of the full sensing range. The proposed sensor is not affected by a bend curvature of up to 80.0 m(-1), unlike previous bend sensors. The proposed sensor is expected to be useful for various applications, including motion capture devices, wearable robots, surgical devices, or generally any device that requires an affordable and low-cost bend sensor. PMID:27347959

  11. The first ANDES elements: 9-DOF plate bending triangles

    NASA Technical Reports Server (NTRS)

    Militello, Carmelo; Felippa, Carlos A.

    1991-01-01

    New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.

  12. Photoinduced Bending of Self-Assembled Azobenzene-Siloxane Hybrid.

    PubMed

    Guo, Sufang; Matsukawa, Kimihiro; Miyata, Takashi; Okubo, Tatsuya; Kuroda, Kazuyuki; Shimojima, Atsushi

    2015-12-16

    A novel azobenzene-siloxane hybrid material displaying photoinduced macroscopic motions has been prepared by one-step organosilane self-assembly. Two types of alkoxysilane precursors with either pendant or bridging azobenzene groups were synthesized via thiol-ene click reactions. Hybrid films with well-ordered lamellar structures were obtained by hydrolysis and polycondensation of these precursors. The film with solely pendant azobenzene groups showed reversible and rapid d-spacing variation upon UV-vis irradiation, which was induced by the trans-cis isomerization of azobenzene moieties. The flexible, free-standing film obtained by co-condensation of two types of precursors showed reversible bending-unbending motions upon UV-vis irradiation. The partial cross-linking between the siloxane layers by bridging azobenzene groups was crucial for photoinduced distortion of the film. This film possesses high elastic modulus, good thermal stability, and shows large amplitude of photoinduced bending-unbending over a wide temperature range. This is the first report on photoinduced macroscopic motions of azobenzene-containing siloxane-based materials. These materials possess great potential for applications in smart devices and energy conversion systems. PMID:26575345

  13. Curled optical patch cord for bending insensitive biomedical imaging endoscope

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Seok; Jeong, Myung Yung; Jung, Chang-Hyun; Ouh, Chi-Hwan; Kang, Hee-Jeon; Han, Young-Geun

    2008-02-01

    Biomedical optical imaging technologies based on optical fibers have been of great interest because of their superiority over conventional bulk-optic counter part in size and integration. Flexible endoscope is a key component to deliver the reflected optical signal from biological tissue to the optical imaging system, such as Optical Coherence Tomography (OCT) and Fiber Confocal Microscopy (FCM). However, conventional optical fibers for the biomedical imaging endoscope have been suffered from a critical wiring problem of a fiber waveguide, which induces additional loss severely. In this work, we have shown excellent properties of holey optical fibers with low bending loss under a minimum bending radius of 10 mm or less, which is almost reaching the wiring limit of endoscope. A curled optical patch cord, like a curled telephone cord, is practically demonstrated for the convenient access of imaging probe to the biological target at the flexible distance. The quality improvement of optical imaging is compared to show the great potential for the endoscopic OCT and endoscopic FCM.

  14. Progress in developing DBTT determinations from miniature disk bend tests

    NASA Astrophysics Data System (ADS)

    Kohse, G.; Ames, M.; Harling, O. K.

    1986-11-01

    Experiments to investigate the possibility of obtaining ductile-to-brittle transition temperature (DBTT) data using bend tests of 3 mm diameter disks are described. A disk specimen 0.40 mm thick with two V-shaped grooves, 0.10 mm deep at right angles to each other along diameters of the disk face, is found to be suitable. In high strain-rate bend testing of materials which exhibit a Charpy V-notch (CVN) DBTT, such specimens undergo a marked change in load/deflection behavior as temperature is lowered. The temperature at which this transition occurs is 145-178 K below the CVN 68 J (50 ft-1b) temperature for three materials tested. There is some evidence that the miniature test transition correlates more consistently with the temperature at which CVN energy reaches a low value such as 7 J. This test offers interesting possibilities for in-service monitoring of critical components such as reactor pressure vessels. Further testing to investigate more fully the relationship between the miniature test and Charpy V-notch results is required.

  15. Composite failure prediction of π-joint structures under bending

    NASA Astrophysics Data System (ADS)

    Huang, Hong-mei; Yuan, Shen-fang

    2012-03-01

    In this article, the composite -joint is investigated under bending loads. The "L" preform is the critical component regarding composite -joint failure. The study is presented in the failure detection of a carbon fiber composite -joint structure under bending loads using fiber Bragg grating (FBG) sensor. Firstly, based on the general finite element method (FEM) software, the 3-D finite element (FE) model of composite -joint is established, and the failure process and every lamina failure load of composite -joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.

  16. Bending mechanics of the red-eared slider turtle carapace.

    PubMed

    Achrai, Ben; Bar-On, Benny; Wagner, H Daniel

    2014-02-01

    The turtle shell is a natural shield that possesses complex hierarchical structure, giving rise to superior mechanical properties. The keratin-covered boney top (dorsal) part of the shell, termed carapace, is composed of rigid sandwich-like ribs made of a central foam-like interior flanked by two external cortices. The ribs are attached to one another in a 3-D interdigitated manner at soft unmineralized collagenous sutures. This unique structural combination promotes sophisticated mechanical response upon predator attacks. In the present study mechanical bending tests were performed to examine the static behavior of the red-eared slider turtle carapace, in different orientations and from various locations, as well as from whole-rib and sub-layer regions. In addition, the suture properties were evaluated as well and compared with those of the rib. A simplified classical analysis was used here to rationalize the experimental results of the whole rib viewed as a laminated composite. The measured strength (~300MPa) and bending modulus (~7-8.5GPa) of the rib were found to be of the same order of magnitude as the strength and modulus of the cortices. The theoretical prediction of the ribs' moduli, predicted in terms of the individual sub-layers moduli, agreed well with the experimental results. The suture regions were found to be more compliant and weaker than the ribs, but comparatively tough, likely due to the interlocking design of the boney zigzag elements. PMID:24333673

  17. Sensor enabled closed-loop bending control of soft beams

    NASA Astrophysics Data System (ADS)

    Case, Jennifer C.; White, Edward L.; Kramer, Rebecca K.

    2016-04-01

    Control of soft-bodied systems is challenging, as the absence of rigidity typically implies distributed deformations and infinite degrees-of-freedom. In this paper, we demonstrate closed-loop control of three elastomer beams that vary in bending stiffness. The most stiff beam is comprised of a single prismatic structure made from a single elastomer. In the next beam, increased flexibility is introduced via an indentation in the elastomer, forming a joint. The most flexible beam uses a softer elastomer in the joint section, along with an indentation. An antagonistic pair of actuators bend the joint while a pair of liquid-metal-embedded strain sensors provide angle feedback to a control loop. We were able to achieve control of the system with a proportional-integral-derivative control algorithm. The procedure we demonstrate in this work is not dependent on actuator and sensor choice and could be applied to to other hardware systems, as well as more complex multi-joint robotic structures in the future.

  18. Overall Thermal Performance of Flexible Piping Under Simulated Bending Conditions

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

    2001-01-01

    Flexible, vacuum-insulated transfer lines for low-temperature applications have higher thermal losses than comparable rigid lines. Typical flexible piping construction uses corrugated tubes, inner and outer, with a multilayer insulation (MLI) system in the annular space. Experiments on vacuum insulation systems in a flexible geometry were conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. The effects of bending were simulated by causing the inner tube to be eccentric with the outer tube. The effects of spacers were simulated in a controlled way by inserting spacer tubes for the length of the cylindrical test articles. Two material systems, standard MLI and a layered composite insulation (LCI), were tested under the full range of vacuum levels using a liquid nitrogen boiloff calorimeter to determine the apparent thermal conductivity (k-value). The results indicate that the flexible piping under simulated bending conditions significantly degrades the thermal performance of the insulation system. These data are compared to standard MLI for both straight and flexible piping configurations. The definition of an overall k-value for actual field installations (k(sub oafi)) is described for use in design and analysis of cryogenic piping systems.

  19. Model for bending actuators that use electrostrictive graft elastomers

    NASA Astrophysics Data System (ADS)

    Costen, Robert C.; Su, Ji; Harrison, Joycelyn S.

    2001-07-01

    Recently, it was reported that an electrostrictive graft elastomer exhibits large electric field-induced strain (4%). Combined with its high mechanical modulus, the elastomer can offer very promising electromechanical properties, in terms of output mechanical energy density, for an electroactive polymeric material. Therefore, it has been considered as one of the candidates that can be used in high performance, low mass actuation devices in many aerospace applications. Various bi-layer-based bending actuators have been designed and fabricated. An analytic model based on beam theory in the strength of materials has been derived for the transverse deflection, or curvature, and the longitudinal strain of the bi-layer beam. The curvature and strain are functions of the applied voltage and the thickness, width, and Young's modulus of the active and passive layers. The model can be used to optimize the performance of electrostrictive graft elastomer-based actuators to meet the requirements of various applications. In this presentation, optimization and sensitivity studies are applied to the bending performance of such actuators.

  20. Model For Bending Actuators That Use Electrostrictive Graft Elastomers

    NASA Technical Reports Server (NTRS)

    Costen, Robert C.; Su, Ji; Harrison, Joycelyn S.

    2001-01-01

    Recently, it was reported that an electrostrictive graft elastomer exhibits large electric field-induced strain (4%). Combined with its high mechanical modulus, the elastomer can offer very promising electromechanical properties, in terms of output mechanical energy density, for an electroactive polymeric material. Therefore, it has been considered as one of the candidates that can be used in high performance, low mass actuation devices in many aerospace applications. Various bilayer- based bending actuators have been designed and fabricated. An analytic model based on beam theory in the strength of materials has been derived for the transverse deflection, or curvature, and the longitudinal strain of the bi-layer beam. The curvature and strain are functions of the applied voltage and the thickness, width, and Young s modulus of the active and passive layers. The model can be used to optimize the performance of electrostrictive graft elastomer-based actuators to meet the requirements of various applications. In this presentation, optimization and sensitivity studies are applied to the bending performance of such actuators.

  1. Experiments and analyses on undermatched interleaf specimens in bending

    SciTech Connect

    Parks, D.M.; Ganti, S.; McClintock, F.A.; Epstein, J.S.; Lloyd, L.R.; Reuter, W.G.

    1995-12-31

    Model weldment fracture specimens have been fabricated, tested, and analyzed using finite elements. The specimens consist of an interleaf of commercially pure titanium diffusion-bonded to a harder alloy titanium. A deep edge crack is introduced symmetrically into the interleaf, and the specimens are loaded in pure bending. Variation of the thickness (2h) of the soft interleaf layer provides insight into effects of weld geometry in strongly undermatched weldments tested in plane strain bending. Ductile crack growth (beyond blunting) initiated at loads giving J {doteq} 95 kJ/m{sup 2} in all specimens. In the thickest interleaf geometries, stable tearing was obtained, but in the thinnest interleaf (2h {doteq} 3mm), crack initiation resulted in a massive pop-in of 5.4 mm across an initial ligament of 12 mm. Finite element studies show that the thinnest interleaf geometry had slightly higher peak stress triaxiality at the beginning of cracking, and that the highest triaxiality extended over a larger region than in the thicker interleaf specimens loaded to the same initiation J-values. More importantly, the blockage of plastic straining above and below the crack tip in the 3 mm interleaf specimen forced higher values of plastic strain to spread forward into the {+-} 45{degree} sector of highest stress triaxiality directly ahead of the crack tip. The higher strains, in conjunction with the slightly higher stress triaxiality, led to the unstable pop-in initiation.

  2. Design of bending multi-layer electroactive polymer actuators

    NASA Astrophysics Data System (ADS)

    Balakrisnan, Bavani; Nacev, Alek; Smela, Elisabeth

    2015-04-01

    The effects of layer thickness and stiffness on multilayer bending actuator performance were investigated with an analytical mechanical model. Performance was evaluated in terms of curvature, blocked force, and work. Multilayer device designs corresponding to dielectric elastomer actuator, ionic polymer metal composite, and conjugated polymer structures were examined. Normalized plots of the performance metrics as functions of relative layer thickness and stiffness are presented that should allow initial, starting-point estimates for designs for particular applications. The results show that to achieve high curvature, layer thickness and stiffness may need to be set above or below particular bounds, or varied together, depending on the device configuration; often there is a broad plateau of combinations that work equally well. There is a conflict between achieving high bending and high force: the former requires the device to behave as much as possible like a simple bilayer with optimal ratios of thickness and modulus, while the latter requires thicker layers and shows little dependence on their moduli. Finally, to maximize work there are areas in the thickness-modulus plane that should be avoided, these areas varying with the configuration in sometimes surprising ways.

  3. Inertia and Double Bending of Light from Equivalence

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L., Jr.

    2010-01-01

    Careful examination of light paths in an accelerated reference frame, with use of Special Relativity, can account fully for the observed bending of light in a gravitational field, not just half of it as reported in 1911. This analysis also leads to a Machian formulation of inertia similar to the one proposed by Einstein in 1912 and later derived from gravitational field equations in Minkowsky Space by Sciama in 1953. There is a clear inference from equivalence that there is some type of inertial mass increase in a gravitational field. It is the purpose of the current paper to suggest that equivalence provides a more complete picture of gravitational effects than previously thought, correctly predicting full light bending, and that since the theory of inertia is derivable from equivalence, any theory based on equivalence must take account of it. Einstein himself clearly was not satisfied with the status of inertia in GRT, as our quotes have shown. Many have tried to account for inertia and met with less than success, for example Davidson s integration of Sciama s inertia into GRT but only for a steady state cosmology [10], and the Machian gravity theory of Brans and Dicke [11]. Yet Mach s idea hasn t gone away, and now it seems that it cannot go away without also disposing of equivalence.

  4. Overall thermal performance of flexible piping under simulated bending conditions

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Augustynowicz, S. D.; Demko, J. A.

    2002-05-01

    Flexible, vacuum-insulated transfer lines for low-temperature applications have higher thermal losses than comparable rigid lines. Typical flexible piping construction uses corrugated tubes, inner and outer, with a multilayer insulation (MLI) system in the annular space. Experiments on vacuum insulation systems in a flexible geometry were conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. The effects of bending were simulated by causing the inner tube to be eccentric with the outer tube. The effects of spacers were simulated in a controlled way by inserting spacer tubes for the length of the cylindrical test articles. Two material systems, standard MLI and a layered composite insulation (LCI), were tested under the full range of vacuum levels using a liquid nitrogen boiloff calorimeter to determine the apparent thermal conductivity (k-value). The results indicate that the flexible piping under simulated bending conditions significantly degrades the thermal performance of the insulation system. These data are compared to standard MLI for both straight and flexible piping configurations. The definition of an overall k-value for actual field installations (koafi) is described for use in design and analysis of cryogenic piping systems.

  5. Electrical Bending and Mechanical Buckling Instabilities in Electrospinning Jets

    NASA Astrophysics Data System (ADS)

    Han, Tao; Reneker, Darrell H.

    2007-03-01

    The electrospinning jet was a continuous fluid flow ejected from the surface of a fluid when the applied electrical force overcomes the surface tension. The jet moved straight away from the tip and then became unstable and bent into coils. This phenomenon is the electrical bending instability [1]. When the distance between the tip and collector was reduced to less than the maximal straight segment length, the electrical bending instability did not occur. The periodic buckling of a fluid jet incident onto a surface is a striking fluid mechanical instability [2]. When axial compressive stress along the jet reached a sufficient value, it produced the fluid mechanics analogue to the buckling of a slender solid column. In the electrospinning, the buckling instability occurred just above the collector where the jet was compressed as it encountered the collector. The buckling frequencies of these jets are in the range of 10^4 to 10^5 Hz. The buckling lengths of these jets are in the range of 10 to 100μm. *Reneker,D.H.; Yarin, A. L.; Fong, H.; Koombhongse, S., Journal of Applied Physics, 87, 4531, 2000 *Tchavdarov B.; Yarin, A. L.; Radev S., Journal of Fluid Mechanics; 253, 593,1993

  6. Xyloglucan for generating tensile stress to bend tree stem.

    PubMed

    Baba, Kei'ichi; Park, Yong Woo; Kaku, Tomomi; Kaida, Rumi; Takeuchi, Miyuki; Yoshida, Masato; Hosoo, Yoshihiro; Ojio, Yasuhisa; Okuyama, Takashi; Taniguchi, Toru; Ohmiya, Yasunori; Kondo, Teiji; Shani, Ziv; Shoseyov, Oded; Awano, Tatsuya; Serada, Satoshi; Norioka, Naoko; Norioka, Shigemi; Hayashi, Takahisa

    2009-09-01

    In response to environmental variation, angiosperm trees bend their stems by forming tension wood, which consists of a cellulose-rich G (gelatinous)-layer in the walls of fiber cells and generates abnormal tensile stress in the secondary xylem. We produced transgenic poplar plants overexpressing several endoglycanases to reduce each specific polysaccharide in the cell wall, as the secondary xylem consists of primary and secondary wall layers. When placed horizontally, the basal regions of stems of transgenic poplars overexpressing xyloglucanase alone could not bend upward due to low strain in the tension side of the xylem. In the wild-type plants, xyloglucan was found in the inner surface of G-layers during multiple layering. In situ xyloglucan endotransglucosylase (XET) activity showed that the incorporation of whole xyloglucan, potentially for wall tightening, began at the inner surface layers S1 and S2 and was retained throughout G-layer development, while the incorporation of xyloglucan heptasaccharide (XXXG) for wall loosening occurred in the primary wall of the expanding zone. We propose that the xyloglucan network is reinforced by XET to form a further connection between wall-bound and secreted xyloglucans in order to withstand the tensile stress created within the cellulose G-layer microfibrils. PMID:19825666

  7. Optical guiding and beam bending in free-electron lasers

    SciTech Connect

    Scharlemann, E.T.

    1987-01-01

    The electron beam in a free-electron laser (FEL) can act as an optical fiber, guiding or bending the optical beam. The refractive and gain effects of the bunched electron beam can compensate for diffraction, making possible wigglers that are many Rayleigh ranges (i.e., characteristic diffraction lengths) long. The origin of optical guiding can be understood by examining gain and refractive guiding in a fiber with a complex index of refraction, providing a mathematical description applicable also to the FEL, with some extensions. In the exponential gain regime of the FEL, the electron equations of motion must be included, but a self-consistent description of exponential gain with diffraction fully included becomes possible. The origin of the effective index of refraction of an FEL is illustrated with a simple example of bunched, radiating dipoles. Some of the properties of the index of refraction are described. The limited experimental evidence for optical beam bending is summarized. The evidence does not yet provide conclusive proof of the existence of optical guiding, but supports the idea. Finally, the importance of refractive guiding for the performance of a high-gain tapered-wiggler FEL amplifier is illustrated with numerical simulations.

  8. Laminar-flow heat transfer downstream from U-bends

    SciTech Connect

    Abdelmessih, A.N

    1987-01-01

    The laminar-flow heat transfer downstream from the unheated, vertical bends in horizontal U-tubes with electrically heated straight tube sections was investigated. Four U-tubes with curvature ratios of 4.84, 7.66, 12.35, and 25.36 were studied. Distilled water and almost-pure ethylene glycol solutions (water content 1 to 5%) were the test fluids. For each test section, local axial and peripheral wall temperatures were measured, and the local peripheral heat-transfer coefficients at the various locations were calculated. The experiments covered the local bulk Reynolds number range of 120 to 2500. The local bulk Prandtl number varied between 4 and 110, while the Grashof number ranged from 2500 to 1,130,000. The uniform wall heat flux ranged from 900 to 4230 Btu/hr.sq.ft (3.12 to 13.33 KW/sq.m.). This investigation permitted a better understanding of the interaction of the primary, secondary, and tertiary flow patterns. Also, a correlation was developed that predicts the heat-transfer coefficient downstream from an unheated U-bend and that can be extended to straight tubes.

  9. Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation

    SciTech Connect

    Railsback, Justin; Singh, Abhishek; Pearce, Ryan; McKnight, Timothy E; Collazo, Ramon; Sitar, Zlatko; Yingling, Yaroslava; Melechko, Anatoli Vasilievich

    2012-01-01

    The understanding of interactions between double stranded (ds) DNA and charged nanoparticles will have a broad bearing on many important applications from drug delivery [ 1 4 ] to DNAtemplated metallization. [ 5 , 6 ] Cationic nanoparticles (NPs) can bind to DNA, a negatively charged molecule, through a combination of electrostatic attraction, groove binding, and intercalation. Such binding events induce changes in the conformation of a DNA strand. In nature, DNA wraps around a cylindrical protein assembly (diameter and height of 6 nm) [ 7 ] with an 220 positive charge, [ 8 ] creating the complex known as chromatin. Wrapping and bending of DNA has also been achieved in the laboratory through the binding of highly charged species such as molecular assemblies, [ 9 , 10 ] cationic dendrimers, [ 11 , 12 ] and nanoparticles. [ 13 15 ] The charge of a nanoparticle plays a crucial role in its ability to induce DNA structural changes. If a nanoparticle has a highly positive surface charge density, the DNA is likely to wrap and bend upon binding to the nanoparticle [ 13 ] (as in the case of chromatin). On the other hand, if a nanoparticle is weakly charged it will not induce dsDNA compaction. [ 9 , 10 , 15 ] Consequently, there is a transition zone from extended to compact DNA conformations which depends on the chemical nature of the nanoparticle and occurs for polycations with charges between 5 and 10. [ 9 ] While the interactions between highly charged NPs and DNA have been extensively studied, the processes that occur within the transition zone are less explored.

  10. Radio occultation bending angle anomalies during tropical cyclones

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J.

    2011-02-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  11. Radio occultation bending angle anomalies during tropical cyclones

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J. K.

    2011-06-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  12. Finite element residual stress analysis of induction heating bended ferritic steel piping

    SciTech Connect

    Kima, Jong Sung; Kim, Kyoung-Soo; Oh, Young-Jin; Chang, Hyung-Young; Park, Heung-Bae

    2014-10-06

    Recently, there is a trend to apply the piping bended by induction heating process to nuclear power plants. Residual stress can be generated due to thermo-mechanical mechanism during the induction heating bending process. It is well-known that the residual stress has important effect on crack initiation and growth. The previous studies have focused on the thickness variation. In part, some studies were performed for residual stress evaluation of the austenitic stainless steel piping bended by induction heating. It is difficult to find the residual stresses of the ferritic steel piping bended by the induction heating. The study assessed the residual stresses of induction heating bended ferriticsteel piping via finite element analysis. As a result, it was identified that high residual stresses are generated on local outersurface region of the induction heating bended ferritic piping.

  13. Theoretical analysis on shear-bending deflection of a ring-shape piezoelectric plate

    NASA Astrophysics Data System (ADS)

    Yu, Zejun; Dong, Shuxiang; Fang, Daining

    2016-02-01

    In this paper, the electromechanical coupling field in shear-bending mode for a ring-shape piezoelectric plate was theoretically established. According to the classical small bending elastic plate theory and piezoelectric constitutive equations, the analytical solution to the bending deformation of the piezo-actuator under electric field and a concentrated or uniformly distributed mechanical load was achieved. The mechanism for generating bending deformation is attributed to axisymmetric shear strain, which further induces the bending deformation of the single ring-shape piezoelectric plate. This mechanism is significant different from that of piezoelectric bimorph or unimorph actuators reported before. Our analysis offers guidance for the optimum design of a ring-shape shear-bending piezo-actuator.

  14. Bending sensor based on intermodal interference properties of two-dimensional waveguide array fiber.

    PubMed

    Li, S; Wang, Zhi; Liu, Y; Han, T; Wu, Z; Wei, C; Wei, H; Li, J; Tong, W

    2012-05-15

    We propose a highly sensitive bending sensor based on the intermodal interference properties of a strongly coupled two-dimentional waveguide array fiber (WAF). The interference resonance peaks formed by the SMF-WAF-SMF Mach-Zehnder interferometer are intrinsically the result of interference between the LP(01)-like supermode and other higher order supermodes, displaying supernormal sensitivity to bending in a wide curvature range. The bending sensitivity of the intermodal MZI is a quadratic function of curvature, and the resonance wavelength shift is up to 100 nm within a curvature range 0-10 m(-1). The fabrication reveals briefness, and temperature response shows little impact on the bend sensing precision. The high bending sensitivity and wide sensing range can make this device a candidate for bending discrimination and measurement in widespread areas. PMID:22627512

  15. Reconciliation and interpretation of Big Bend National Park particulate sulfur source apportionment: results from the Big Bend Regional Aerosol and Visibility Observational Study--part I.

    PubMed

    Schichtel, Bret A; Gebhart, Kristi A; Malm, William C; Barna, Michael G; Pitchford, Marc L; Knipping, Eladio M; Tombach, Ivar H

    2005-11-01

    The Big Bend Regional Aerosol and Visibility Observational (BRAVO) study was an intensive monitoring study from July through October 1999 followed by extensive assessments to determine the causes and sources of haze in Big Bend National Park, located in Southwestern Texas. Particulate sulfate compounds are the largest contributor of haze at Big Bend, and chemical transport models (CTMs) and receptor models were used to apportion the sulfate concentrations at Big Bend to North American source regions and the Carbón power plants, located 225 km southeast of Big Bend in Mexico. Initial source attribution methods had contributions that varied by a factor of > or =2. The evaluation and comparison of methods identified opposing biases between the CTMs and receptor models, indicating that the ensemble of results bounds the true source attribution results. The reconciliation of these differences led to the development of a hybrid receptor model merging the CTM results and air quality data, which allowed a nearly daily source apportionment of the sulfate at Big Bend during the BRAVO study. The best estimates from the reconciliation process resulted in sulfur dioxide (SO2) emissions from U.S. and Mexican sources contributing approximately 55% and 38%, respectively, of sulfate at Big Bend. The distribution among U.S. source regions was Texas, 16%; the Eastern United States, 30%; and the Western United States, 9%. The Carbón facilities contributed 19%, making them the largest single contributing facility. Sources in Mexico contributed to the sulfate at Big Bend on most days, whereas contributions from Texas and Eastern U.S. sources were episodic, with their largest contributions during Big Bend sulfate episodes. On the 20% of the days with the highest sulfate concentrations, U.S. and Mexican sources contributed approximately 71% and 26% of the sulfate, respectively. However, on the 20% of days with the lowest sulfate concentrations, Mexico contributed 48% compared with 40

  16. Sharp bends associated with deep scours in a tropical river: The river Mahakam (East Kalimantan, Indonesia)

    NASA Astrophysics Data System (ADS)

    Vermeulen, B.; Hoitink, A. J. F.; Berkum, S. W.; Hidayat, H.

    2014-07-01

    Autogenic scouring in sharp river bends has received ample attention in laboratory and modeling studies. These studies have significantly advanced our understanding of how flow processes are influenced by strong curvature and how they affect the bathymetry. Here we present a 300 km reach of the Mahakam River in Indonesia, which features several sharp bends (W/R > 0.5), providing a unique field data set to validate existing knowledge on sharp bends. Scour depths were found to strongly exceed what can be expected based on existing understanding of sharp bends and are highly correlated with curvature. A comprehensive stream reconnaissance was carried out to compare the occurrence of sharp bends and deep scours with lateral bank migration. Histograms of the occurrence of erosive, stable, advancing, and bar-type banks as a function of curvature quantify the switch from a mildly curved bend regime to a sharp bend regime. In mild bends, outer banks erode and inner banks advance. In sharp bends the erosion pattern inverts. Outer banks stabilize or advance, while inner banks erode. In sharply curved river bends, bars occur near the outer banks that become less erosive for higher curvatures. Inner banks become more erosive for higher curvatures but nevertheless accommodate the larger portion of exposed bars. No relation was found between the land cover adjacent to the river and the occurrence of sharp bends. Soil processes may play a crucial role in the formation of sharp bends, which is inferred from iron and manganese concretions observed in the riverbanks, indicating ferric horizons and early stages of the formation of plinthic horizons. Historical topographic maps show the planform activity of the river is low, which may relate to the scour holes slowing down planimetric development.

  17. Use of Generalized Mass in the Interpretation of Dynamic Response of BENDING-TORSION Coupled Beams

    NASA Astrophysics Data System (ADS)

    ESLIMY-ISFAHANY, S. H. R.; BANERJEE, J. R.

    2000-11-01

    The interpretation of mode shapes and dynamic response of bending-torsion coupled beams is assessed by using the concept of generalized mass. In the first part of this investigation, the free vibratory motion of bending-torsion coupled beams is studied in detail. The conventional method of interpreting the normal modes of vibration consisting of bending displacements and torsional rotations is shown to be inadequate and replaced by an alternative method which is focussed on the constituent parts of the generalized mass arising from bending and torsional displacements. Basically, the generalized mass in a particular mode is identified and examined in terms of bending, torsion and bending-torsion coupling effects. It is demonstrated that the contribution of individual components in the expression of the generalized mass of a normal mode is a much better indicator in characterizing a coupled mode. It is also shown that the usually adopted criteria of plotting bending displacement and torsional rotations to describe a coupled mode can be deceptive and misleading. In the second part of the investigation, attention is focussed on the dynamic response characteristics of bending-torsion coupled beams when subjected to random bending or torsional loads. A normal mode approach is used to establish the total response. The input random excitation is assumed to be stationary and ergodic so that with the linearity assumption, the output spectrum of the response is obtained by using the frequency response function. The contribution of each normal mode to the overall response is isolated. Particular emphasis is placed on bending-induced torsional response and torsion-induced bending response. A number of case studies involving different types of bending-torsion coupled beams with Cantilever end conditions are presented. The limitations of existing methods of modal interpretation are highlighted, and an insight into the mode selection for response analysis is provided.

  18. Contained Rupture in HeartMate II Outflow Graft Bend Relief Disconnection.

    PubMed

    Chua, Kim Chai; Tan, Teing Ee; Lim, Chong Hee; Kerk, Ka Lee; Sivathasan, Cumaraswamy

    2016-03-01

    Thoratec recalled their HeartMate II ventricular assist device in March 2012 after some problems related to disconnection of the bend relief. Abrasion on the pump outflow graft caused by a disconnected bend relief is rare. We report the case of a 49-year-old man in whom a disconnected bend relief caused a puncture in the outflow graft, resulting in a contained hematoma, requiring outflow graft replacement. PMID:25348159

  19. Springback control in sheet metal bending by laser-assisted bending: Experimental analysis, empirical and neural network modelling

    NASA Astrophysics Data System (ADS)

    Gisario, A.; Barletta, M.; Conti, C.; Guarino, S.

    2011-12-01

    The present investigation deals with the control of springback phenomena in the bending process of aluminium sheets by hybrid forming process. Metal substrates were pre-bent to nominal shapes on a built-ad-hoc mould after being constrained on it. Then, they were post-treated by high power diode laser to prevent the deformation of the pre-bent sheets after the release of the constraints. The extent of springback phenomena were estimated by measuring the difference between the nominal bending angles and those achieved on the unconstrained substrates after laser post-treatments. Analytical models, aimed at predicting the springback by varying the setting of the operational parameters of the forming process, were developed. Neural network solutions were also proposed to improve the matching between experimental and numerical data, with the Multi-Layer Perceptrons trained by Back-Propagation algorithm being the fittest one. On this basis, a control modulus very useful to practitioners for automation and simulation purposes was built-on.

  20. Effect of Centrifugal Transverse Wakefield for Microbunch in Bend

    SciTech Connect

    Stupakov, G.V.; /SLAC

    2006-03-22

    We calculate centrifugal force for a short bunch in vacuum moving in a circular orbit and estimate the emittance growth of the beam in a bend due to this force. Many of the basic features of the coherent synchrotron radiation (CSR) of short bunches and its effect on beam dynamics in accelerators are now well established. The effect is usually described in terms of the longitudinal force, or wakefield, that causes the energy loss in the beam, and also redistributes the energy between the particles by accelerating the head and decelerating the tail of the bunch. Coherent radiation becomes most important for short bunches and high currents. More subtle features of CSR such as transition effect due to the entrance to and exit from the bend, CSR force in the undulator, and shielding due to the close metallic boundaries have been also studied. Much less is known about the transverse force in a short bunch moving on a circular orbit. The problem has been treated in several papers beginning from R. Talman's work, who pointed out that the centrifugal force of a rotating bunch can result in a noticeable tune shift of betatron oscillations. Later, an important correction to the Talman paper has been added, where it was shown that due to the energy variation in the bunch, the effect of the transverse force proportional to R{sup -1} is canceled, and the residual effect is of the order of R{sup -2}, that is much smaller than originally predicted. Recently, however, Derbenev and Shiltsev found the centrifugal force of the order of R{sup -1} that differs from Talman's result by a logarithmic factor only. Taking into account the existing controversy in the literature, in this paper, we consider the transverse force in a bunch based on simple physical arguments, starting from a dc beam. We will derive the centrifugal force for a relativistic coasting beam in vacuum, and then generalize the result for a short bunch, and estimate its effect on the emittance growth in a bend

  1. 50-Ma initiation of Hawaiian-Emperor bend records major change in Pacific plate motion.

    PubMed

    Sharp, Warren D; Clague, David A

    2006-09-01

    The Hawaiian-Emperor bend has played a prominent yet controversial role in deciphering past Pacific plate motions and the tempo of plate motion change. New ages for volcanoes of the central and southern Emperor chain define large changes in volcanic migration rate with little associated change in the chain's trend, which suggests that the bend did not form by slowing of the Hawaiian hot spot. Initiation of the bend near Kimmei seamount about 50 million years ago (MA) was coincident with realignment of Pacific spreading centers and early magmatism in western Pacific arcs, consistent with formation of the bend by changed Pacific plate motion. PMID:16946069

  2. Nanoscale Bending of Multilayered Boron Nitride and Graphene Ribbons: Experiment and Objective Molecular Dynamics Calculations

    NASA Astrophysics Data System (ADS)

    Nikiforov, Ilia; Tang, Dai-Ming; Wei, Xianlong; Dumitricǎ, Traian; Golberg, Dmitri

    2012-07-01

    By combining experiments performed on nanoribbons in situ within a high-resolution TEM with objective molecular dynamics simulations, we reveal common mechanisms in the bending response of few-layer-thick hexagonal boron nitride and graphene nanoribbons. Both materials are observed forming localized kinks in the fully reversible bending experiments. Microscopic simulations and theoretical analysis indicate platelike bending behavior prior to kinking, in spite of the possibility of interlayer sliding, and give the critical curvature for the kinking onset. This behavior is distinct from the rippling and kinking of multi- and single-wall nanotubes under bending. Our findings have implications for future study of nanoscale layered materials, including nanomechanical device design.

  3. Arbitrary bending of electromagnetic waves using realizable inhomogeneous and anisotropic materials.

    PubMed

    Jiang, Wei Xiang; Cui, Tie Jun; Zhou, Xiao Yang; Yang, Xin Mi; Cheng, Qiang

    2008-12-01

    We propose an optical transformation to bend electromagnetic waves by designing proper inhomogeneous and anisotropic materials, which are hereinafter referred to as metamaterials (MTMs). When the waveguide bends are filled with MTMs, the incident waves will pass through the bends without any reflections (for full-parameter MTMs) or with very small reflections (for simplified-parameter MTMs). When MTMs are placed in air, the incident waves will be bent to any designed directions. We also discuss the wave bending using layered homogeneous uniaxial MTMs, which can be easily realized using artificial structures. PMID:19256968

  4. Modeling and measurement of losses in silicon-on-insulator resonators and bends.

    PubMed

    Xiao, Shijun; Khan, Maroof H; Shen, Hao; Qi, Minghao

    2007-08-20

    We present an analytical model to quantify losses in resonators and bends without uncertain contributions from fiber coupling in/out or waveguide cleavage facets. With resonators in add-drop configuration, intrinsic losses are calculated from the free spectral range, through-port extinction and drop-port bandwidth. We fabricated and characterized silicon-on-insulator resonator for loss analysis. At 1.55 mum, racetrack resonators with a bending radius of 4.5 mum show intrinsic losses as small as 0.14+/-0.014 dB/round-trip. Meanwhile, intrinsic losses increase up to 1.23 dB/round-trip in the racetrack resonator that has a bending radius of 2.25 mum. Losses in a 180 degrees bend are estimated as a half of the intrinsic losses in these racetrack resonators, i.e., 0.07+/-0.007 dB/turn for a bending radius of 4.5 mum and 0.62 dB/turn for a bending radius of 2.25 mum. Loss in a 90 degrees bend with a radius of 4.5 mum is determined to be 0.06+/-0.006 dB/turn at 1.55 mum. The losses in 180 degrees or 90 degrees bends are found to be mainly due to the transition loss between waveguide bends and straight waveguides. PMID:19547408

  5. The use of a bend singlemode-multimode-singlemode (SMS) fibre structure for vibration sensing

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Yang, Minwei; Yuan, Jinhui; Chan, Hau Ping; Ma, Youqiao; Semenova, Yuliya; Wang, Pengfei; Yu, Chongxiu; Farrell, Gerald

    2014-11-01

    A bend singlemode-multimode-singlemode (SMS) fibre structure based vibration sensor is proposed and developed. This sensor configuration is very simple and employs a bend SMS fibre structure and a broadband optical source. The vibration applied to the bend SMS fibre structure will change the bend radius and hence the intensity of the transmitted optical power will also vary. Experimental results show that the sensor can detect both vibration frequencies and amplitudes over a broad range with good sensitivity, from a hertz to 12 kHz.

  6. Continuous Curvilinear Capsulorhexis in Cataract Surgery Using a Modified 3-Bend Cystotome

    PubMed Central

    Zeng, Yuan; Gao, Jian-hua

    2015-01-01

    We modified a 2-bend cystotome for continuous curvilinear capsulorhexis (CCC) in manual or phacoemulsification cataract surgery to improve the safety and ease of performance. A 26G needle was converted into a cystotome with 3 bends. In this retrospective study, the performance of modified 3-bend cystotome was compared with conventional 2-bend cystotome. During cataract surgery, in the 3-bend cystotome group, mean completion time of CCC was shorter, mean times of viscoelastic agent supplement were less, and CCC success rate was higher than that in 2-bend group. Complication incidence, such as postoperative transient corneal edema and irreparable V-shaped tear, was also lower in 3-bend group. No posterior capsular rupture or no other complication was observed in either group. A polymethyl methacrylate intraocular lens or a hydrogel intraocular lens was implanted in the capsular bag in all eyes. We conclude that it is safe and efficient to accomplish a CCC using the 3-bend cystotome due to its ability to sustain the anterior chamber depth (ACD) and keep the posterior lip intact. Using the 3-bend cystotome also allowed for an adequate view into the anterior chamber from lack of wound deformation. PMID:26509078

  7. Continuous Curvilinear Capsulorhexis in Cataract Surgery Using a Modified 3-Bend Cystotome.

    PubMed

    Zeng, Yuan; Gao, Jian-Hua

    2015-01-01

    We modified a 2-bend cystotome for continuous curvilinear capsulorhexis (CCC) in manual or phacoemulsification cataract surgery to improve the safety and ease of performance. A 26G needle was converted into a cystotome with 3 bends. In this retrospective study, the performance of modified 3-bend cystotome was compared with conventional 2-bend cystotome. During cataract surgery, in the 3-bend cystotome group, mean completion time of CCC was shorter, mean times of viscoelastic agent supplement were less, and CCC success rate was higher than that in 2-bend group. Complication incidence, such as postoperative transient corneal edema and irreparable V-shaped tear, was also lower in 3-bend group. No posterior capsular rupture or no other complication was observed in either group. A polymethyl methacrylate intraocular lens or a hydrogel intraocular lens was implanted in the capsular bag in all eyes. We conclude that it is safe and efficient to accomplish a CCC using the 3-bend cystotome due to its ability to sustain the anterior chamber depth (ACD) and keep the posterior lip intact. Using the 3-bend cystotome also allowed for an adequate view into the anterior chamber from lack of wound deformation. PMID:26509078

  8. Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis.

    PubMed

    Kim, Hoonbae; Ye, Donghyun; Won, Beomhee; Yu, SeGi; Jung, Donggeun

    2016-05-01

    Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed. PMID:27483935

  9. Anisotropic surface roughness enhances the bending response of ionic polymer-metal composite (IPMC) artificial muscles

    NASA Astrophysics Data System (ADS)

    Stoimenov, Boyko L.; Rossiter, Jonathan M.; Mukai, Toshiharu

    2007-01-01

    Demands from the fields of bio-medical engineering and biologically-inspired robotics motivate a growing interest in actuators with properties similar to biological muscle, including ionic polymer-metal composites (IPMC), the focus of this study. IPMC actuators consist of an ion-conductive polymer membrane, coated with thin metal electrodes on both sides and bend when voltage is applied. Some of the advantages of IPMC actuators are their softness, lack of moving parts, easy miniaturization, light weight and low actuation voltage. When used in bio-mimetic robotic applications, such as a snake-like swimming robot, locomotion speed can be improved by increasing the bending amplitude. However, it cannot be improved much by increasing the driving voltage, because of water electrolysis. To enhance the bending response of IPMCs we created a "preferred" bending direction by anisotropic surface modification. Introduction of anisotropic roughness with grooves across the length of the actuator improved the bending response by a factor of 2.1. Artificially introduced cracks on the electrodes in direction, in which natural cracks form by bending, improved bending response by a factor of 1.6. Anisotropic surface modification is an effective method to enhance the bending response of IPMC actuators and does not compromise their rigidity under loads perpendicular to the bending plane.

  10. Bending a beam by a generalized ideal elastomeric gel

    PubMed Central

    Cai, Shengqiang

    2015-01-01

    A hybrid beam with a gel layer bonded on the top of an elastic non-swellable substrate has been commonly adopted to make various sensors and actuators. Usually, different models need to be developed for the hybrid beam when different gels are used in the system. In this article, based on the generalized ideal elastomeric gel model, we formulate a unified relationship between the swelling of hydrogels and the bending curvature of the elastic beam, which is independent of specific swelling mechanisms of gels. We further illustrate that the equations derived in the article can be used to validate the ideal elastomeric gel model and measure the elasticity of polymer networks of the gels. PMID:25792965

  11. Automated Wing Twist And Bending Measurements Under Aerodynamic Load

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Martinson, S. D.

    1996-01-01

    An automated system to measure the change in wing twist and bending under aerodynamic load in a wind tunnel is described. The basic instrumentation consists of a single CCD video camera and a frame grabber interfaced to a computer. The technique is based upon a single view photogrammetric determination of two dimensional coordinates of wing targets with a fixed (and known) third dimensional coordinate, namely the spanwise location. The measurement technique has been used successfully at the National Transonic Facility, the Transonic Dynamics Tunnel, and the Unitary Plan Wind Tunnel at NASA Langley Research Center. The advantages and limitations (including targeting) of the technique are discussed. A major consideration in the development was that use of the technique must not appreciably reduce wind tunnel productivity.

  12. Small bending and stretching of sandwich-type shells

    NASA Technical Reports Server (NTRS)

    Reissner, Eric

    1950-01-01

    A theory has been developed for small bending and stretching of sandwich-type shells. This theory is an extension of the known theory of homogeneous thin elastic shells. It was found that two effects are important in the present problem, which are not normally of importance in the theory of curved shells: (1) the effect of transverse shear deformation and (2) the effect of transverse normal stress deformation. The first of these two effects has been known to be of importance in the theory of plates and beams. The second effect was found to occur in a manner which is typical for shells and has no counterpart in flat-plate theory. The general results of this report have been applied to the solution of problems concerning flat plates, circular rings, circular cylindrical shells, and spherical shells. In each case numerical examples have been given, illustrating the magnitude of the effects of transverse shear and normal stress deformation.

  13. Geometrically nonlinear bending analysis of laminated composite plate

    NASA Astrophysics Data System (ADS)

    Dash, Padmanav; Singh, B. N.

    2010-10-01

    In this work, a transverse bending of shear deformable laminated composite plates in Green-Lagrange sense accounting for the transverse shear and large rotations are presented. Governing equations are developed in the framework of higher order shear deformation theory. All higher order terms arising from nonlinear strain-displacement relations are included in the formulation. The present plate theory satisfies zero transverse shear strains conditions at the top and bottom surfaces of the plate in von-Karman sense. A C0 isoparametric finite element is developed for the present nonlinear model. Numerical results for the laminated composite plates of orthotropic materials with different system parameters and boundary conditions are found out. The results are also compared with those available in the literature. Some new results with different parameters are also presented.

  14. Estimation of blade airloads from rotor blade bending moments

    NASA Technical Reports Server (NTRS)

    Bousman, William G.

    1987-01-01

    This paper presents a method for the estimation of blade airloads, based on the measurements of flap bending moments. In this procedure, the blade rotation in vacuum modes is calculated, and the airloads are expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The method was validated by comparing the calculated airload distribution with the original wind tunnel measurements which were made using ten modes and twenty measurement stations. Good agreement between the predicted and the measured airloads was found up to 0.90 R, but the agreement degraded towards the blade tip. The method is shown to be quite robust to the type of experimental problems that could be expected to occur in the testing of full-scale and model-scale rotors.

  15. Influence of nanobubbles on the bending of microcantilevers

    SciTech Connect

    Jeon, Sangmin; Desikan, Ramya; Thundat, Thomas George

    2006-03-01

    Young's equation, which is commonly used for determining the contact angle of liquid drops on a solid surface, ignores the vertical component of the surface energy. Although this force is extremely small and its effect on the solid can be ignored, it plays a significant role for flexible surfaces such as microcantilevers. A gold-coated silicon microcantilever and a dodecanethiol coated silicon microcantilever were used to detect real-time formation of nanobubbles on their surfaces when exposed to air-rich water. As air nanobubbles form on the surfaces of the cantilever, the cantilever undergoes bending, and we relate this to the vertical component of surface energy in Young's equation. This implies that the vertical component of the surface tension should be considered for flexible solid surfaces, and the formation of nanobubbles should be avoided when cantilevers are used as sensors to avoid artifacts.

  16. Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

    NASA Astrophysics Data System (ADS)

    Baltov, Anguel; Yanakieva, Ana

    2015-12-01

    Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

  17. Acoustic emission monitoring of recycled aggregate concrete under bending

    NASA Astrophysics Data System (ADS)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  18. Design of a Variable Thickness Plate to Focus Bending Waves

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Lin, Sz-Chin Steven; Cabell, Randolph H.; Huang, Tony Jun

    2012-01-01

    This paper describes the design of a thin plate whose thickness is tailored in order to focus bending waves to a desired location on the plate. Focusing is achieved by smoothly varying the thickness of the plate to create a type of lens, which focuses structural-borne energy. Damping treatment can then be positioned at the focal point to efficiently dissipate energy with a minimum amount of treatment. Numerical simulations of both bounded and unbounded plates show that the design is effective over a broad frequency range, focusing traveling waves to the same region of the plate regardless of frequency. This paper also quantifies the additional energy dissipated by local damping treatment installed on a variable thickness plate relative to a uniform plate.

  19. Rheology of a Twist-bend Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Salili, Seyyed Muhammad; Kim, Chanjoong; Sprunt, Samuel; Gleeson, James; Parri, Owain; Jakli, Antal; Kim Lab Team; Merck Lab Team

    2015-03-01

    First detailed flow shear alignment studies and rheological measurements in the twist-bend nematic (Ntb) liquid crystalline phase of odd numbered flexible dimer molecules is presented. It is found that the Ntb phase is strongly shear-thinning. At shear stresses below 1 Pa the apparent viscosity of the Ntb phase is 1000 times larger than in the nematic phase. At stresses above 10 Pa the Ntb viscosity drops by two orders of magnitude and the material exhibits Newtonian fluid behavior. The results are consistent with the behavior of a system with pseudo-layer structure with layer spacing determined by the heliconical pitch. From the measurements of dynamic modulus we estimate the compression modulus of the pseudo-layers to be B ~ 2 kPa this value is discussed within the context of a simple theoretical model based upon a coarse-grained elastic free energy. www.jakligroup.com.

  20. ATP transport in saccular cerebral aneurysms at arterial bends.

    PubMed

    Imai, Yohsuke; Sato, Kodai; Ishikawa, Takuji; Comerford, Andrew; David, Tim; Yamaguchi, Takami

    2010-03-01

    ATP acts as an extracellular signaling molecule in purinergic signaling that regulates vascular tone. ATP binds purinergic P2 nucleotide receptors on endothelial cells. Understanding the mass transport of ATP to endothelial cells by blood flow is thus important to predict functional changes in aneurysmal walls. While some clinical observations indicate a difference of wall pathology between ruptured and unruptured aneurysms, no study has focused on the mass transport in aneurysms. We investigated the characteristics of ATP concentration at aneurysmal wall using a numerical model of ATP transport in aneurysms formed at arterial bends. The magnitude of ATP concentration at the aneurysmal wall was significantly smaller than that at the arterial wall. In particular, significantly low concentration was predicted at the proximal side of the aneurysmal sac. A strong correlation was revealed between the inflow flux at the aneurysmal neck and the resultant concentration at the aneurysmal wall. PMID:20012692

  1. Bending overload and implant fracture: a retrospective clinical analysis.

    PubMed

    Rangert, B; Krogh, P H; Langer, B; Van Roekel, N

    1995-01-01

    Thirty-nine patients with implant fractures treated by three of the authors have been analyzed as to probable causes. Thirty-five (90%) of the fractures occurred in the posterior region. Thirty (77%) of the prostheses were supported by one or two implants, which were exposed to a combination of cantilever load magnification and bruxism or heavy occlusal forces. It was concluded that prostheses supported by one or two implants and replacing missing posterior teeth are subjected to an increased risk of bending overload. The literature review indicates that the fracture frequency is low in these situations and this study demonstrates that with appropriate treatment planning, such overload situations can essentially be prevented. PMID:7615329

  2. Stiffened plate bending analysis by the boundary element method

    NASA Astrophysics Data System (ADS)

    Fernandes, G. R.; Venturini, W. S.

    In this work, the plate bending formulation of the boundary element method (BEM) based on the Kirchhoff's hypothesis, is extended to the analysis of stiffened elements usually present in building floor structures. Particular integral representations are derived to take directly into account the interactions between the beams forming grid and surface elements. Equilibrium and compatibility conditions are automatically imposed by the integral equations, which treat this composite structure as a single body. Two possible procedures are shown for dealing with plate domain stiffened by beams. In the first, the beam element is considered as a stiffer region requiring therefore the discretization of two internal lines with two unknowns per node. In the second scheme, the number of degrees of freedom along the interface is reduced by two by assuming that the cross-section motion is defined by three independent components only.

  3. Bending Fatigue of Carburized Steel at Very Long Lives

    NASA Astrophysics Data System (ADS)

    Nelson, D. V.; Long, Z.

    2016-01-01

    The bending fatigue behavior of two carburized steels is investigated for lives between approximately 105 and 108 cycles. Cracks are observed to start at sub-surface inclusions and develop features on fracture surfaces resembling "fish eyes" in appearance. This type of sub-surface cracking tends to govern fatigue strength at long lives. Previous studies of "fish eye" fatigue in carburized steel have been relatively few and have mainly considered failures originating at depths beneath a carburized case, where compressive residual stresses are minimal and hardness values approach those in the core. This study provides fatigue data for cracks originating within cases at various depths where compressive residual stresses are substantial and hardness is much higher than in the core. Fatigue strength is predicted by a simple model, accounting for the influence of residual stresses and hardness values at the different depths at which cracks started. Predictions of fatigue strength are compared with data generated in this study.

  4. Bending-torsion flutter of a highly swept advanced turboprop

    NASA Technical Reports Server (NTRS)

    Mehmed, O.; Kaza, K. R. V.; Lubomski, J. F.; Kielb, R. E.

    1981-01-01

    Experimental and analytical results are presented for a bending-torsion flutter phenomena encountered during wind-tunnel testing of a ten-bladed, advanced, high-speed propeller (turboprop) model with thin airfoil sections, high blade sweep, low aspect ratio, high solidity and transonic tip speeds. Flutter occurred at free-stream Mach numbers of 0.6 and greater and when the relative tip Mach number (based on vector sum of axial and tangential velocities) reached a value of about one. The experiment also included two- and five-blade configurations. The data indicate that aerodynamic cascade effects have a strong destabilizing influence on the flutter boundary. The data was correlated with analytical results which include aerodynamic cascade effects and good agreement was found.

  5. Bending induced self-organized switchable gratings on polymeric substrates.

    PubMed

    Parra-Barranco, Julian; Oliva-Ramirez, Manuel; Gonzalez-Garcia, Lola; Alcaire, Maria; Macias-Montero, Manuel; Borras, Ana; Frutos, Fabian; Gonzalez-Elipe, Agustin R; Barranco, Angel

    2014-08-13

    We present a straightforward procedure of self-surface patterning with potential applications as large area gratings, invisible labeling, optomechanical transducers, or smart windows. The methodology is based in the formation of parallel micrometric crack patterns when polydimethylsiloxane foils coated with tilted nanocolumnar SiO2 thin films are manually bent. The SiO2 thin films are grown by glancing angle deposition at room temperature. The results indicate that crack spacing is controlled by the film nanostructure independently of the film thickness and bending curvature. They also show that the in-plane microstructural anisotropy of the SiO2 films due to column association perpendicular to the growth direction determines the anisotropic formation of parallel cracks along two main axes. These self-organized patterned foils are completely transparent and work as customized reversible diffraction gratings under mechanical activation. PMID:25007108

  6. Recuperation of Electron Beam in the Coolers with Electrostatic Bending

    SciTech Connect

    Bryzgunov, M.; Panasyuk, V.; Parkhomchuk, V.; Reva, V.; Vedenev, M.

    2006-03-20

    An important aspect of the cooler operation is the collector efficiency. The low loss current improves the vacuum condition, the radiation condition and makes the easy design of the power supply system. This article deals with the reuse of collector at the electrostatic bending in the toroidal section. It's possible to compensate the centrifugal force for the secondary electrons by the electric field because the effect of both forces is independent from the direction of the electron longitudinal velocity. As result the secondary electrons may return into the collector after reflection from the gun. Nonzero loss current is defined mainly by the energy spectrum of the secondary electrons. The review of the experimental data for the different cooler is described in this article. The range of the electron energy is 2-300 keV. Some physical model is proposed for the experiment explanations.

  7. High-pressure sensor using piezoelectric bending resonators

    NASA Astrophysics Data System (ADS)

    Bao, Xiaoqi; Sherrit, Stewart; Takano, Nobuyuki

    2016-04-01

    A novel design of pressure sensor based on piezoelectric bending resonator is described in this paper. The resonator is isolated from and mechanically coupled to the surrounding fluid using a sealed enclosure. The pressure applied to the enclosure induces a compressive stress to the resonator and reduces its resonance frequency. In principle the mechanism allows for achieving large resonance frequency shifts close to 100% of the resonance frequency. A high-pressure sensor based on the mechanism was designed for down-hole pressure monitoring in oil wells. The sensor is potentially remotely-readable via the transmission of an electromagnetic signal down a waveguide formed by the pipes in the oil well. The details of the pressure sensor design and verification by FE analysis and initial test results of a preliminary prototype are presented in this paper.

  8. Stabilization of Helical Macromolecular Phases by Confined Bending

    NASA Astrophysics Data System (ADS)

    Williams, Matthew J.; Bachmann, Michael

    2015-07-01

    By means of extensive replica-exchange simulations of generic coarse-grained models for helical polymers, we systematically investigate the structural transitions into all possible helical phases for flexible and semiflexible elastic polymers with self-interaction under the influence of torsion barriers. The competing interactions lead to a variety of conformational phases including disordered helical arrangements, single helices, and ordered, tertiary helix bundles. Most remarkably, we find that a bending restraint entails a clear separation and stabilization of the helical phases. This aids in understanding why semiflexible polymers such as double-stranded DNA tend to form pronounced helical structures and proteins often exhibit an abundance of helical structures, such as helix bundles, within their tertiary structure.

  9. Spring-back of flexible roll forming bending process

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Kim, D. H.; Jung, D. W.

    2015-12-01

    Simulations are now widely used in the field of roll forming because of their convenience. Simulations provide a low cost, secure and fast analysis tool. Flexible roll forming provides the desired shapes with a one time forming process. For roll forming, the velocity of the sheet and friction are important factors to attain an ideal shape. Because it is a complicated process, simulations provide a better understanding of the roll forming process. Simulations were peformed using ABAQUS software linked to elastic-plastic modules which we developed taking into account of interactions between these fields [1]. The application of this method makes it possible to highlight the strain-stress and mechanical behaviour laws and the spring-back. Thus, the flexible roll forming and bending process can bewell described by the simulation software and guide the actual machine.

  10. Fluctuation Modes of a Twist-Bend Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Parsouzi, Z.; Shamid, S. M.; Borshch, V.; Challa, P. K.; Baldwin, A. R.; Tamba, M. G.; Welch, C.; Mehl, G. H.; Gleeson, J. T.; Jakli, A.; Lavrentovich, O. D.; Allender, D. W.; Selinger, J. V.; Sprunt, S.

    2016-04-01

    We report a dynamic light-scattering study of the fluctuation modes in a thermotropic liquid crystalline mixture of monomer and dimer compounds that exhibits the twist-bend nematic (NTB ) phase. The results reveal a spectrum of overdamped fluctuations that includes two nonhydrodynamic modes and one hydrodynamic mode in the NTB phase, and a single nonhydrodynamic mode plus two hydrodynamic modes (the usual nematic optic axis or director fluctuations) in the higher temperature, uniaxial nematic phase. The properties of these fluctuations and the conditions for their observation are comprehensively explained by a Landau-de Gennes expansion of the free-energy density in terms of heliconical director and helical polarization fields that characterize the NTB structure, with the latter serving as the primary order parameter. A "coarse-graining" approximation simplifies the theoretical analysis and enables us to demonstrate quantitative agreement between the calculated and experimentally determined temperature dependence of the mode relaxation rates.

  11. Homogenization of long fiber reinforced composites including fiber bending effects

    NASA Astrophysics Data System (ADS)

    Poulios, Konstantinos; Niordson, Christian F.

    2016-09-01

    This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows to maintain the kinematics of the two material phases independent from the assumed constitutive models, so that stress-deformation relationships, can be expressed in the framework of hyper-elasticity and hyper-elastoplasticity for the fiber and the matrix materials respectively. The bending stiffness of the reinforcing fibers is captured by higher order strain terms, resulting in an accurate representation of the micro-mechanical behavior of the composite. Numerical examples show that the accuracy of the proposed model is very close to a non-homogenized finite-element model with an explicit discretization of the matrix and the fibers.

  12. Meshless Local Petrov-Galerkin Method for Bending Problems

    NASA Technical Reports Server (NTRS)

    Phillips, Dawn R.; Raju, Ivatury S.

    2002-01-01

    Recent literature shows extensive research work on meshless or element-free methods as alternatives to the versatile Finite Element Method. One such meshless method is the Meshless Local Petrov-Galerkin (MLPG) method. In this report, the method is developed for bending of beams - C1 problems. A generalized moving least squares (GMLS) interpolation is used to construct the trial functions, and spline and power weight functions are used as the test functions. The method is applied to problems for which exact solutions are available to evaluate its effectiveness. The accuracy of the method is demonstrated for problems with load discontinuities and continuous beam problems. A Petrov-Galerkin implementation of the method is shown to greatly reduce computational time and effort and is thus preferable over the previously developed Galerkin approach. The MLPG method for beam problems yields very accurate deflections and slopes and continuous moment and shear forces without the need for elaborate post-processing techniques.

  13. Bending Fatigue Strength of Austempered Ductile Iron Spur Gears

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masashi; Tamura, Ryo; Inoue, Katsumi; Narita, Yukihito

    This paper deals with an experimental evaluation of bending fatigue strength for austempered ductile iron (ADI) spur gears. The module is 2.5 and the number of teeth is 26 in the test gears. The material of the test gears corresponds to Japan Industrial Standard (JIS) FCAD1100-15. Some gears are processed by one of two types of fine particle bombarding (FPB). The surface roughness is slightly increased by FPB. The obtained strengths are 623 MPa for the as-austempered gears, and 1011 and 1085 MPa for the gears after FPB. The strength is expressed by the fillet stress level, which is calculated by FEM. The strength of a gear with the same dimensions made of carburized SCr420H alloy steel is 1205 MPa, and the strength of the ADI gear is approximately half that of the carburized steel gear. The FPB process has a significant effect on the ADI gear, improving its strength by 62-74%.

  14. Polyelectrolyte gels as bending actuators: modeling and numerical simulation

    NASA Astrophysics Data System (ADS)

    Wallmersperger, Thomas; Keller, Karsten; Attaran, Abdolhamid

    2013-04-01

    Polyelectrolyte gels are ionic electroactivematerials. They have the ability to react as both, sensors and actuators. As actuators they can be used e.g. as artificial muscles or drug delivery control; as sensors they may be used for measuring e.g. pressure, pH or other ion concentrations in the solution. In this research both, anionic and cationic polyelectrolyte gels placed in aqueous solution with mobile anions and cations are investigated. Due to external stimuli the polyelectrolyte gels can swell or shrink enormously by the uptake or delivery of solvent. In the present research a coupled multi-field problem within a continuum mechanics framework is proposed. The modeling approach introduces a set of equations governing multiple fields of the problem, including the chemical field of the ionic species, the electrical field and the mechanical field. The numerical simulation is performed by using the Finite Element Method. Within the study some test cases will be carried out to validate our model. In the works by Gülch et al., the application of combined anionic-cationic gels as grippers was shown. In the present research for an applied electric field, the change of the concentrations and the electric potential in the complete polymer is simulated by the given formulation. These changes lead to variations in the osmotic pressure resulting in a bending of different polyelectrolyte gels. In the present research it is shown that our model is capable of describing the bending behavior of anionic or cationic gels towards the different electrodes (cathode or anode).

  15. Sensitivity analysis of channel-bend hydraulics influenced by vegetation

    NASA Astrophysics Data System (ADS)

    Bywater-Reyes, S.; Manners, R.; McDonald, R.; Wilcox, A. C.

    2015-12-01

    Alternating bars influence hydraulics by changing the force balance of channels as part of a morphodynamic feedback loop that dictates channel geometry. Pioneer woody riparian trees recruit on river bars and may steer flow, alter cross-stream and downstream force balances, and ultimately change channel morphology. Quantifying the influence of vegetation on stream hydraulics is difficult, and researchers increasingly rely on two-dimensional hydraulic models. In many cases, channel characteristics (channel drag and lateral eddy viscosity) and vegetation characteristics (density, frontal area, and drag coefficient) are uncertain. This study uses a beta version of FaSTMECH that models vegetation explicitly as a drag force to test the sensitivity of channel-bend hydraulics to riparian vegetation. We use a simplified, scale model of a meandering river with bars and conduct a global sensitivity analysis that ranks the influence of specified channel characteristics (channel drag and lateral eddy viscosity) against vegetation characteristics (density, frontal area, and drag coefficient) on cross-stream hydraulics. The primary influence on cross-stream velocity and shear stress is channel drag (i.e., bed roughness), followed by the near-equal influence of all vegetation parameters and lateral eddy viscosity. To test the implication of the sensitivity indices on bend hydraulics, we hold calibrated channel characteristics constant for a wandering gravel-bed river with bars (Bitterroot River, MT), and vary vegetation parameters on a bar. For a dense vegetation scenario, we find flow to be steered away from the bar, and velocity and shear stress to be reduced within the thalweg. This provides insight into how the morphodynamic evolution of vegetated bars differs from unvegetated bars.

  16. Video observations of bed form morphodynamics in a meander bend

    NASA Astrophysics Data System (ADS)

    Palmsten, Margaret L.; Kozarek, Jessica L.; Calantoni, Joseph

    2015-09-01

    A new optical remote sensing technique for estimating water depth from an oblique camera view is described. The water surface and the bed were imaged simultaneously to create time-dependent maps of the water surface velocities and the bed elevations that can be used to validate numerical models at high spatial and temporal resolution. The technique was applied in a sandy meander bend at the University of Minnesota Saint Anthony Falls Laboratory Outdoor StreamLab. The root mean square differences between optical estimates of the bed and in situ observations ranged between 0.01 and 0.03 m. Mean bed form wavelength was 0.73 m and mean crest height was 0.07 m, but both varied with distance around the meander bend. Bed form classification varied with distance downstream, and sinuosity of bed forms varied with local radius of curvature. Bed form roughness scaled similarly to other natural riverine environments although wavelength and height magnitude and variability were larger than predicted by empirical formulations for straight reaches. Bed form translation rate varied between 1 and 5 mm s-1. Estimates of velocity from particle image velocimetry (PIV) on the water surface were ˜10% higher than in situ observations collected ˜0.05 m below the water surface. Using the PIV observations to drive simple equations for bed load sediment flux, we explained up to 72% of the observed variance in downstream sediment flux. The new methodology described here provides nonintrusive, high spatial and temporal resolution measurements of both the bed and the flow.

  17. HYDRODYNAMICS AND SEDIMENT TRANSPORT IN LOWER MISSISSIPPI RIVER MEANDER BENDS (LOUISIANA): IMPLICATIONS FOR LARGE SEDIMENT DIVERSIONS

    NASA Astrophysics Data System (ADS)

    Allison, M. A.; McCorquodale, A.; Meselhe, E. A.

    2009-12-01

    Field data collection and numerical modeling is being conducted in the lower Mississippi River in the region of a meander bend at Myrtle Grove, LA (river km 96 above Head of Passes) in support of a proposed large water and sediment diversion (1,130-2,830 cms) for coastal wetland restoration. Field studies in October 2008, April and May 2009, at discharges ranging from 11,000-21,000 cms, examined the role of bend dynamics on sediment transport through this reach relative to control sites further downriver and USGS monitoring stations upriver. Suspended loads and grain size character measured by ADCP (velocities and backscatter), isokinetic point sampler (P-63), and optical sensors (LISST, OBS, transmissometer) indicate that during the rising-to-high discharge phase, sand lifting off from the downstream edge of the lateral bar upriver of the bend augments that carried from further upriver, and is entrained in the upper 10-25m of the water column. This excess suspended sand is advected around the bend before concentrations are reduced to background levels over the lateral bar downstream of the bend. Bedload transport rates measured by repeat swath bathymetric mapping of migrating dunes are comparable upstream of the bend, downstream, and in the control sites. However, no bedforms are observed in the bend thalweg (up to 60 m deep) supporting the dominance of suspended sand transport in the bend. Both 1D (HEC-RAS and HEC6-T) and 3D (Flow3D) numerical hydrodynamic and sediment transport modeling is underway to simulate this process and the large-scale eddy present in the bend that generates upriver transport along the inside of the meander bend at all observed discharges. Our preliminary results suggest that the outside of meander bends might be an appropriate site for sediment diversions that draw near-surface water from this sediment-rich layer.

  18. Oroclinal bending and evidence against the Pangea megashear: The Cantabria-Asturias arc (northern Spain)

    NASA Astrophysics Data System (ADS)

    Weil, Arlo B.; van der Voo, Rob; van der Pluijm, Ben A.

    2001-11-01

    The Cantabria-Asturias arc of southwestern Europe is a highly curved Variscan belt that formed along the ancient plate boundary between Gondwana and Laurussia during the assembly of Pangea. New paleomagnetic data from 59 sites in the southern limb of the arc were combined with previously published data from 109 sites to determine the evolution of the arc. A previously unrecognized postrotation magnetization is found in the southern limb, refuting earlier models of arc formation that concluded secondary rotation of only 50% of present-day arc curvature. The new data show that the arc underwent true (100%) oroclinal bending of an originally linear belt in a two-stage tectonic history. This history represents two regional compression phases: (1) east-west in the late Carboniferous (Pennsylvanian) and (2) north-south in the Permian (both in present-day coordinates). The north-south compression phase coincides with the northward movement of Gondwana and its final collision with Laurussia. This tectonic scenario argues against an indentor scenario, and does not support a 3500 km dextral megashear proposed in earlier reconstructions.

  19. Soft tissue artifact evaluation of the cervical spine in motion patterns of flexion and lateral bending: a preliminary study.

    PubMed

    Wang, Jiajia; Lui, Zhongwen; Qian, Zhihui; Ren, Luquan

    2016-01-01

    Background. Soft tissue artifact (STA) is increasingly becoming a focus of research as the skin marker method is widely employed in motion capture technique. At present, medical imaging methods provide reliable ways to investigate the cervical STA. Among these approaches, magnetic resonance imaging (MRI) is a highly preferred tool because of its low radiation. Methods. In the study, the 3D spatial location of vertebral landmarks and corresponding skin markers of the spinous processes of the second (C2), fifth (C5), and sixth (C6) cervical levels during flexion and lateral bending were investigated. A series of static postures were scanned using MRI. Skin deformation was obtained by the Mimics software. Results. Results shows that during flexion, the maximum skin deformation occurs at C6, in the superior-inferior (Z) direction. Upon lateral bending, the maximum skin displacement occurs at C2 level, in the left-right (Y) direction. The result presents variability of soft tissue in the terms of direction and magnitude, which is consistent with the prevailing opinion. Discussion. The results testified variability of cervical STA. Future studies involving large ranges of subject classification, such as age, sex, height, gravity, and etc. should be performed to completely verify the existing hypothesis on human cervical skin deformation. PMID:27069821

  20. Soft tissue artifact evaluation of the cervical spine in motion patterns of flexion and lateral bending: a preliminary study

    PubMed Central

    Wang, Jiajia; Lui, Zhongwen; Ren, Luquan

    2016-01-01

    Background. Soft tissue artifact (STA) is increasingly becoming a focus of research as the skin marker method is widely employed in motion capture technique. At present, medical imaging methods provide reliable ways to investigate the cervical STA. Among these approaches, magnetic resonance imaging (MRI) is a highly preferred tool because of its low radiation. Methods. In the study, the 3D spatial location of vertebral landmarks and corresponding skin markers of the spinous processes of the second (C2), fifth (C5), and sixth (C6) cervical levels during flexion and lateral bending were investigated. A series of static postures were scanned using MRI. Skin deformation was obtained by the Mimics software. Results. Results shows that during flexion, the maximum skin deformation occurs at C6, in the superior–inferior (Z) direction. Upon lateral bending, the maximum skin displacement occurs at C2 level, in the left–right (Y) direction. The result presents variability of soft tissue in the terms of direction and magnitude, which is consistent with the prevailing opinion. Discussion. The results testified variability of cervical STA. Future studies involving large ranges of subject classification, such as age, sex, height, gravity, and etc. should be performed to completely verify the existing hypothesis on human cervical skin deformation. PMID:27069821

  1. Twist, tilt, and orientational order at the nematic to twist-bend nematic phase transition of 1″,9″-bis(4-cyanobiphenyl-4'-yl) nonane: A dielectric, 2H NMR, and calorimetric study

    NASA Astrophysics Data System (ADS)

    Robles-Hernández, Beatriz; Sebastián, Nerea; de la Fuente, M. Rosario; López, David O.; Diez-Berart, Sergio; Salud, Josep; Ros, M. Blanca; Dunmur, David A.; Luckhurst, Geoffrey R.; Timimi, Bakir A.

    2015-12-01

    The nature of the nematic-nematic phase transition in the liquid crystal dimer 1″,9″-bis(4-cyanobiphenyl-4'-yl) nonane (CB9CB) has been investigated using techniques of calorimetry, dynamic dielectric response measurements, and 2H NMR spectroscopy. The experimental results for CB9CB show that, like the shorter homologue CB7CB, the studied material exhibits a normal nematic phase, which on cooling undergoes a transition to the twist-bend nematic phase (NTB), a uniaxial nematic phase, promoted by the average bent molecular shape, in which the director tilts and precesses describing a conical helix. Modulated differential scanning calorimetry has been used to analyze the nature of the NTB-N phase transition, which is found to be weakly first order, but close to tricritical. Additionally broadband dielectric spectroscopy and 2H magnetic resonance studies have revealed information on the structural characteristics of the recently discovered twist-bend nematic phase. Analysis of the dynamic dielectric response in both nematic phases has provided an estimate of the conical angle of the heliconical structure for the NTB phase. Capacitance measurements of the electric-field realignment of the director in initially planar aligned cells have yielded values for the splay and bend elastic constants in the high temperature nematic phase. The bend elastic constant is small and decreases with decreasing temperature as the twist-bend phase is approached. This behavior is expected theoretically and has been observed in materials that form the twist-bend nematic phase. 2H NMR measurements characterize the chiral helical twist identified in the twist-bend nematic phase and also allow the determination of the temperature dependence of the conical angle and the orientational order parameter with respect to the director.

  2. Calculation of the transverse kicks generated by the bends of a hollow electron lens

    SciTech Connect

    Stancari, Giulio

    2014-03-25

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam in high-energy accelerators. They were used in the Fermilab Tevatron collider for abort-gap clearing, beam-beam compensation, and halo scraping. A beam-beam compensation scheme based upon electron lenses is currently being implemented in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. This work is in support of a conceptual design of hollow electron beam scraper for the Large Hadron Collider. It also applies to the implementation of nonlinear integrable optics with electron lenses in the Integrable Optics Test Accelerator at Fermilab. We consider the axial asymmetries of the electron beam caused by the bends that are used to inject electrons into the interaction region and to extract them. A distribution of electron macroparticles is deposited on a discrete grid enclosed in a conducting pipe. The electrostatic potential and electric fields are calculated using numerical Poisson solvers. The kicks experienced by the circulating beam are estimated by integrating the electric fields over straight trajectories. These kicks are also provided in the form of interpolated analytical symplectic maps for numerical tracking simulations, which are needed to estimate the effects of the electron lens imperfections on proton lifetimes, emittance growth, and dynamic aperture. We outline a general procedure to calculate the magnitude of the transverse proton kicks, which can then be generalized, if needed, to include further refinements such as the space-charge evolution of the electron beam, magnetic fields generated by the electron current, and longitudinal proton dynamics.

  3. Magnetic fish-robot based on multi-motion control of a flexible magnetic actuator.

    PubMed

    Kim, Sung Hoon; Shin, Kyoosik; Hashi, Shuichiro; Ishiyama, Kazushi

    2012-09-01

    This paper presents a biologically inspired fish-robot driven by a single flexible magnetic actuator with a rotating magnetic field in a three-axis Helmholtz coil. Generally, magnetic fish-robots are powered by alternating and gradient magnetic fields, which provide a single motion such as bending the fish-robot's fins. On the other hand, a flexible magnetic actuator driven by an external rotating magnetic field can create several gaits such as the bending vibration, the twisting vibration, and their combination. Most magnetic fish-like micro-robots do not have pectoral fins on the side and are simply propelled by the tail fin. The proposed robot can swim and perform a variety of maneuvers with the addition of pectoral fins and control of the magnetic torque direction. In this paper, we find that the robot's dynamic actuation correlates with the magnetic actuator and the rotating magnetic field. The proposed robot is also equipped with new features, such as a total of six degrees of freedom, a new control method that stabilizes posture, three-dimensional swimming, a new velocity control, and new turning abilities. PMID:22550128

  4. Reversible Bending Behaviors of Photomechanical Soft Actuators Based on Graphene Nanocomposites.

    PubMed

    Niu, Dong; Jiang, Weitao; Liu, Hongzhong; Zhao, Tingting; Lei, Biao; Li, Yonghao; Yin, Lei; Shi, Yongsheng; Chen, Bangdao; Lu, Bingheng

    2016-01-01

    Photomechanical nanocomposites embedded with light-absorbing nanoparticles show promising applications in photoresponsive actuations. Near infrared (nIR)-responsive nanocomposites based photomechanical soft actuators can offer lightweight functional and underexploited entry into soft robotics, active optics, drug delivery, etc. A novel graphene-based photomechanical soft actuators, constituted by Polydimethylsiloxane (PDMS)/graphene-nanoplatelets (GNPs) layer (PDMS/GNPs) and pristine PDMS layer, have been constructed. Due to the mismatch of coefficient of thermal expansion of two layers induced by dispersion of GNPs, controllable and reversible bendings response to nIR light irradiation are observed. Interestingly, two different bending behaviors are observed when the nIR light comes from different sides, i.e., a gradual single-step photomechanical bending towards PDMS/GNPs layer when irradiation from PDMS side, while a dual-step bending (finally bending to the PDMS/GNPs side but with an strong and fast backlash at the time of light is on/off) when irradiation from PDMS/GNPs side. The two distinctive photomechanical bending behaviors are investigated in terms of heat transfer and thermal expansion, which reveals that the distinctive bending behaviors can be attributed to the differences in temperature gradients along the thickness when irradiation from different sides. In addition, the versatile photomechanical bending properties will provide alternative way for drug-delivery, soft robotics and microswitches, etc. PMID:27265380

  5. Extraordinary Bending Effects in MoS2 , Phosphorene, and Graphene Nanoribbons

    NASA Astrophysics Data System (ADS)

    Yu, Liping; Ruzsinszky, Adrienn; Perdew, John

    The two-dimensional (2D) materials show great potential for flexible electronics and energy applications. They have remarkable mechanical, electronic, thermal and optical properties, which are often coupled to each other. In this talk, we shall present our first principles study on the bending effects in the electronic structure of MoS2, phosphorene, and graphene nanoribbons. We predict that mechanical bending, as a unique attribute of thin 2D materials, can be used to control conductivity and Fermi-level shift. We find that bending can control the charge localization of top valence bands in both MoS2 and phosphorene nanoribbons. The donor-like in-gap edge-states of armchair MoS2 ribbon and their associated Fermi-level pinning can be removed by bending. A bending-controllable new in-gap state and accompanying direct-indirect gap transition are predicted in armchair phosphorene nanoribbon. We demonstrate that such emergent bending effects are realizable in experiment and can be attributed to the highly non-uniform and enormously large local in-plane strains induced by bending. The bending stiffness as wells as the effective thickness of 2D materials are also derived from first principles. The work was supported as part of the Center for the Computational Design of Functional Layered Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

  6. Performance study of macro-bending EDFA/Raman hybrid optical fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Mahran, O.

    2015-10-01

    In this paper, we present an analytical study of a (macro-bending EDFA)/Raman hybrid optical amplifier. The bending radius is 4 mm with EDFA length 10 m with forward pump power in the range (100-500 mW) and Raman amplifier length (12-55 km) with backward pump power variations (80-200 mW) is considered in our model. Due to bending loss in EDFA, the gain of hybrid amplifier is increased to ~7 dB more than the normal EDFA/Raman hybrid amplifier and the noise figure is decreased by ~2 dB rather than without macro-bending EDFA/Raman hybrid amplifier. The signal to noise ratio (OSNR) calculations shows a better performance of macro-bending EDFA/Raman hybrid amplifier than without macro-bending one. A flat gain is obtained in the signal wavelength region (1560-1600 nm), which is the L-band. The calculated results for macro-bending case are compared with experimental results of normal case by Lee et al., in the L-band showing an increase in the gain, reduction in the noise figure and more gain flatness at the input signal -20 dBm for macro-bending EDFA/Raman hybrid amplifier.

  7. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  8. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  9. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  10. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  11. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  12. Incisor crown bending strength correlates with diet and incisor curvature in anthropoid primates.

    PubMed

    Deane, Andrew S

    2015-02-01

    Anthropoid incisors are large relative to the postcanine dentition and function in the preprocessing of food items. Previous analyses of anthropoid incisor allometry and shape demonstrate that incisor morphology is correlated with preferred foods and that more frugivorous anthropoids have larger and more curved incisors. Although the relationship between incisal crown curvature and preferred foods has been well documented in extant and fossil anthropoids, the functional significance of curvature variation has yet to be conclusively established. Given that an increase in crown curvature will increase maximum linear crown dimensions, and bending resistance is a function of linear crown dimensions, it is hypothesized that incisor crown curvature functons to increase incisor crown resistance to bending forces. This study uses beam theory to calculate the mesiodistal and labiolingual bending strengths of the maxillary and mandibular incisors of hominoid and platyrrhine taxa with differing diets and variable degrees of incisal curvature. Results indicate that bending strength correlates with incisal curvature and that frugivores have elevated incisor bending resistance relative to folivores. Maxillary central incisor bending strengths further discriminate platyrrhine and hominoid hard- and soft-object frugivores suggesting this crown is subjected to elevated occlusal loading relative to other incisors. These results are consistent with the hypothesis that incisor crown curvature functions to increase incisor crown resistance to bending forces but does not preclude the possibility that incisor bending strength is a composite function of multiple dentognathic variables including, but not limited to, incisor crown curvature. PMID:25156755

  13. The Battle of Horseshoe Bend: Collision of Cultures. Teaching with Historic Places.

    ERIC Educational Resources Information Center

    Horak, Virginia

    This lesson is based on the National Register of Historic Places registration file "Horseshoe Bend Battlefield," documents from archives at Horseshoe Bend National Military Park, and other resources. The lesson can be used in units on American Indian culture, early 19th-century westward expansion, the War of 1812, European American and American…

  14. Reversible Bending Behaviors of Photomechanical Soft Actuators Based on Graphene Nanocomposites

    PubMed Central

    Niu, Dong; Jiang, Weitao; Liu, Hongzhong; Zhao, Tingting; Lei, Biao; Li, Yonghao; Yin, Lei; Shi, Yongsheng; Chen, Bangdao; Lu, Bingheng

    2016-01-01

    Photomechanical nanocomposites embedded with light-absorbing nanoparticles show promising applications in photoresponsive actuations. Near infrared (nIR)-responsive nanocomposites based photomechanical soft actuators can offer lightweight functional and underexploited entry into soft robotics, active optics, drug delivery, etc. A novel graphene-based photomechanical soft actuators, constituted by Polydimethylsiloxane (PDMS)/graphene-nanoplatelets (GNPs) layer (PDMS/GNPs) and pristine PDMS layer, have been constructed. Due to the mismatch of coefficient of thermal expansion of two layers induced by dispersion of GNPs, controllable and reversible bendings response to nIR light irradiation are observed. Interestingly, two different bending behaviors are observed when the nIR light comes from different sides, i.e., a gradual single-step photomechanical bending towards PDMS/GNPs layer when irradiation from PDMS side, while a dual-step bending (finally bending to the PDMS/GNPs side but with an strong and fast backlash at the time of light is on/off) when irradiation from PDMS/GNPs side. The two distinctive photomechanical bending behaviors are investigated in terms of heat transfer and thermal expansion, which reveals that the distinctive bending behaviors can be attributed to the differences in temperature gradients along the thickness when irradiation from different sides. In addition, the versatile photomechanical bending properties will provide alternative way for drug-delivery, soft robotics and microswitches, etc. PMID:27265380

  15. 78 FR 50454 - Entergy Operations, Inc., River Bend Station, Unit 1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-19

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Entergy Operations, Inc., River Bend Station, Unit 1 AGENCY: Nuclear Regulatory Commission. ACTION...-47, issued to Entergy Operations, Inc. (the licensee), for operation of the River Bend Station,...

  16. 78 FR 53482 - Entergy Operations, Inc., River Bend Station, Unit 1; Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-29

    ... environment (78 FR 50454; August 19, 2013). This exemption is effective upon issuance. Dated at Rockville... COMMISSION Entergy Operations, Inc., River Bend Station, Unit 1; Exemption 1.0 Background Entergy Operations... operation of the River Bend Station, Unit 1 (RBS). The license provides, among other things, that...

  17. 75 FR 25204 - Foreign-Trade Zone 125 - South Bend, Indiana

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-07

    ... (74 FR 1170, 1/12/09; correction 74 FR 3987, 1/22/09). The ASF is an option for grantees for the... Foreign-Trade Zones Board Foreign-Trade Zone 125 - South Bend, Indiana Application for Reorganization... Industrial Park, South Bend (St. Joseph County); and Site 2: (21 acres) - located at 1507 South Olive...

  18. Galvanic vestibular stimulation may improve anterior bending posture in Parkinson's disease.

    PubMed

    Okada, Yohei; Kita, Yorihiro; Nakamura, Junji; Kataoka, Hiroshi; Kiriyama, Takao; Ueno, Satoshi; Hiyamizu, Makoto; Morioka, Shu; Shomoto, Koji

    2015-05-01

    This study investigated the effects of binaural monopolar galvanic vestibular stimulation (GVS), which likely stimulates the bilateral vestibular system, on the anterior bending angle in patients with Parkinson's disease (PD) with anterior bending posture in a single-blind, randomized sham-controlled crossover trial. The seven PD patients completed two types of stimulation (binaural monopolar GVS and sham stimulation) applied in a random order 1 week apart. We measured each patient's anterior bending angles while he or she stood with eyes open and eyes closed before/after the stimulations. The anterior bending angles in both the eyes-open and the eyes-closed conditions were significantly reduced after the GVS. The amount of change in the eyes-closed condition post-GVS was significantly larger than that by sham stimulation. The amount of change in anterior bending angles in the GVS condition was not significantly correlated with Unified Parkinson's Disease Rating Scale motor score, disease duration, the duration of the postural deformities, and the anterior bending angles before the GVS. Binaural monopolar GVS might improve anterior bending posture in PD patients, irrespective of the duration and the severity of disease and postural deformities. Binaural monopolar GVS might be a novel treatment strategy to improve anterior bending posture in PD. PMID:25793635

  19. 75 FR 42119 - Notice of Intent to Repatriate Cultural Items: High Desert Museum, Bend, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-20

    ... National Park Service Notice of Intent to Repatriate Cultural Items: High Desert Museum, Bend, OR AGENCY... cultural items in the possession of the High Desert Museum, Bend, OR, that meet the definition of... notice. In 1990, Native American cultural items were donated to the High Desert Museum by the Roger...

  20. Reversible Bending Behaviors of Photomechanical Soft Actuators Based on Graphene Nanocomposites

    NASA Astrophysics Data System (ADS)

    Niu, Dong; Jiang, Weitao; Liu, Hongzhong; Zhao, Tingting; Lei, Biao; Li, Yonghao; Yin, Lei; Shi, Yongsheng; Chen, Bangdao; Lu, Bingheng

    2016-06-01

    Photomechanical nanocomposites embedded with light-absorbing nanoparticles show promising applications in photoresponsive actuations. Near infrared (nIR)-responsive nanocomposites based photomechanical soft actuators can offer lightweight functional and underexploited entry into soft robotics, active optics, drug delivery, etc. A novel graphene-based photomechanical soft actuators, constituted by Polydimethylsiloxane (PDMS)/graphene-nanoplatelets (GNPs) layer (PDMS/GNPs) and pristine PDMS layer, have been constructed. Due to the mismatch of coefficient of thermal expansion of two layers induced by dispersion of GNPs, controllable and reversible bendings response to nIR light irradiation are observed. Interestingly, two different bending behaviors are observed when the nIR light comes from different sides, i.e., a gradual single-step photomechanical bending towards PDMS/GNPs layer when irradiation from PDMS side, while a dual-step bending (finally bending to the PDMS/GNPs side but with an strong and fast backlash at the time of light is on/off) when irradiation from PDMS/GNPs side. The two distinctive photomechanical bending behaviors are investigated in terms of heat transfer and thermal expansion, which reveals that the distinctive bending behaviors can be attributed to the differences in temperature gradients along the thickness when irradiation from different sides. In addition, the versatile photomechanical bending properties will provide alternative way for drug-delivery, soft robotics and microswitches, etc.