Science.gov

Sample records for rough rod bundles

  1. Heat Transfer Enhancement By Three-Dimensional Surface Roughness Technique In Nuclear Fuel Rod Bundles

    NASA Astrophysics Data System (ADS)

    Najeeb, Umair

    This thesis experimentally investigates the enhancement of single-phase heat transfer, frictional loss and pressure drop characteristics in a Single Heater Element Loop Tester (SHELT). The heater element simulates a single fuel rod for Pressurized Nuclear reactor. In this experimental investigation, the effect of the outer surface roughness of a simulated nuclear rod bundle was studied. The outer surface of a simulated fuel rod was created with a three-dimensional (Diamond-shaped blocks) surface roughness. The angle of corrugation for each diamond was 45 degrees. The length of each side of a diamond block is 1 mm. The depth of each diamond block was 0.3 mm. The pitch of the pattern was 1.614 mm. The simulated fuel rod had an outside diameter of 9.5 mm and wall thickness of 1.5 mm and was placed in a test-section made of 38.1 mm inner diameter, wall thickness 6.35 mm aluminum pipe. The Simulated fuel rod was made of Nickel 200 and Inconel 625 materials. The fuel rod was connected to 10 KW DC power supply. The Inconel 625 material of the rod with an electrical resistance of 32.3 kO was used to generate heat inside the test-section. The heat energy dissipated from the Inconel tube due to the flow of electrical current flows into the working fluid across the rod at constant heat flux conditions. The DI water was employed as working fluid for this experimental investigation. The temperature and pressure readings for both smooth and rough regions of the fuel rod were recorded and compared later to find enhancement in heat transfer coefficient and increment in the pressure drops. Tests were conducted for Reynold's Numbers ranging from 10e4 to 10e5. Enhancement in heat transfer coefficient at all Re was recorded. The maximum heat transfer co-efficient enhancement recorded was 86% at Re = 4.18e5. It was also observed that the pressure drop and friction factor increased by 14.7% due to the increased surface roughness.

  2. Coolant mixing in LMFBR rod bundles and outlet plenum mixing transients. Progress report

    SciTech Connect

    Todreas, N.E.; Golay, M.W.; Wold, L.

    1981-02-01

    Four tasks are reported on: bundle geometry (wrapped and bare rods), subchannel geometry (bare rods), LMFBR outlet plenum flow mixing, and theoretical determination of local temperature fields in LMFBR fuel rod bundles. (DLC)

  3. Overview of rod-bundle thermal-hydraulic analysis

    SciTech Connect

    Sha, W.T.

    1980-11-01

    Three methods used in rod-bundle thermal-hydraulic analysis are summarized. These methods are: (1) subchannel analysis, and its inherent assumptions are clearly stated; (2) porous medium formulation with volume porosity, surface permeability, distributed resistance and distributed heat source (sink) - the concept of surface permeability is new in porous medium formulation, and greatly facilitates modeling anisotropic effects; and (3) benchmark rod-bundle thermal-hydraulic analysis using a boundary-fitted coordinate system, and it represents the most rigorous method to date. For laminar flow, this method gives solutions without any assumptions and it requires information on rod bundle geometry and thermal physical properties of the fluid. Basic limitations and merits of each method are discussed in detail. 19 refs., 6 figs., 1 tab.

  4. LWR fuel rod bundle behavior under severe fuel damage conditions

    SciTech Connect

    Kuczera, B. Hagen, S.; Hofmann, P.

    1988-01-01

    Light water reactor (LWR) safety research and development activities conducted at Kernforschungszentrum Karlsruhe have recently been reorganized with a concentrated mission under the LWR safety project group. The topics treated relate mainly to severe-accident analysis research and source term assessment as well as to source term mitigation measures. A major part of the investigations concerns the early phase of a severe core meltdown accident, specifically LWR rod assembly behavior under sever fuel damage (SFD) conditions. To determine the extent of fuel rod damage, including the relocation behavior of molten reaction products, damage propagation, time-dependent H{sub 2} generation from clad oxidation, and fragmentation of oxygen-embrittled materials during cooldown and quenching, extensive out-of-pile rod bundle experiments have been initiated in the new CORA test facility. The bundle parameters, such as rod dimensions, rod pitch, and grid spacer, can be adjusted to both pressurized water reactor (PWR) and boiling water reactor (BWR) conditions. Currently, the test program consists of 15 experiments in which the influence of Inconel grid spacer, (Ag,In,Cd)-absorber rods (PWR) and of B{sub 4}C control blades (BWR) on fuel damage initiation and damage propagation are being investigated for different boundary conditions. As of June 1988, four bundle tests had been successfully carried out for PWR accident conditions.

  5. Coolant mixing in LMFBR rod bundles and outlet plenum mixing transients. Progress report, March 1, 1980-May 31, 1980

    SciTech Connect

    Todreas, N.E.; Golay, M.W.; Wolf, L.

    1980-01-01

    Experimental and theoretical work is reported on four tasks: bundle geometry (wrapped and bare rods), subchannel geometry (bare rods), LMFBR outlet plenum flow mixing, and theoretical local temperature files in LMFBR fuel rod bundles. (DLC)

  6. Method of bundling rods so as to form an optical fiber preform

    DOEpatents

    Kliner, Dahv A. V.; Koplow, Jeffery P.

    2004-03-30

    The present invention provides a simple method for fabricating fiber-optic glass preforms having complex refractive index configurations and/or dopant distributions in a radial direction with a high degree of accuracy and precision. The method teaches bundling together a plurality of glass rods of specific physical, chemical, or optical properties and wherein the rod bundle is fused in a manner that maintains the cross-sectional composition and refractive-index profiles established by the position of the rods.

  7. Subchannel thermal-hydraulic modeling of an APT tungsten target rod bundle

    SciTech Connect

    Hamm, L.L.; Shadday, M.A. Jr.

    1997-09-01

    The planned target for the Accelerator Production of Tritium (APT) neutron source consists of an array of tungsten rod bundles through which D{sub 2}O coolant flows axially. Here, a scoping analysis of flow through an APT target rod bundle was conducted to demonstrate that lateral cross-flows are important, and therefore subchannel modeling is necessary to accurately predict thermal-hydraulic behavior under boiling conditions. A local reactor assembly code, FLOWTRAN, was modified to model axial flow along the rod bundle as flow through three concentric heated annular passages.

  8. Anisotropic Turbulence Modeling for Accurate Rod Bundle Simulations

    SciTech Connect

    Baglietto, Emilio

    2006-07-01

    An improved anisotropic eddy viscosity model has been developed for accurate predictions of the thermal hydraulic performances of nuclear reactor fuel assemblies. The proposed model adopts a non-linear formulation of the stress-strain relationship in order to include the reproduction of the anisotropic phenomena, and in combination with an optimized low-Reynolds-number formulation based on Direct Numerical Simulation (DNS) to produce correct damping of the turbulent viscosity in the near wall region. This work underlines the importance of accurate anisotropic modeling to faithfully reproduce the scale of the turbulence driven secondary flows inside the bundle subchannels, by comparison with various isothermal and heated experimental cases. The very low scale secondary motion is responsible for the increased turbulence transport which produces a noticeable homogenization of the velocity distribution and consequently of the circumferential cladding temperature distribution, which is of main interest in bundle design. Various fully developed bare bundles test cases are shown for different geometrical and flow conditions, where the proposed model shows clearly improved predictions, in close agreement with experimental findings, for regular as well as distorted geometries. Finally the applicability of the model for practical bundle calculations is evaluated through its application in the high-Reynolds form on coarse grids, with excellent results. (author)

  9. Void Fraction in a Four by Four Rod Bundle under a Stagnant Condition

    NASA Astrophysics Data System (ADS)

    Kamei, Akihiro; Hosokawa, Shigeo; Tomiyama, Akio; Kinoshita, Ikuo; Murase, Michio

    In the case of a hypothetical failure of a residual heat removal (RHR) systems under mid-loop operation, vapor generated in a reactor core forms two-phase flow in a stagnant liquid and rises the water level in the core. The vapor flows into a steam generator through a hot leg, and condenses in the steam generator. Since the flow rate of vapor from the reactor core to the hot leg depends on the water level and the void fraction α in the reactor core, the reliable analysis of the RHR failure cannot be carried out without accurately estimating the void fraction in the reactor core. Although a number of studies on void fractions in two-phase flows in rod bundles have been carried out, there are few experimental data on void fractions in rod bundles under the stagnant condition. Void fractions in four by four rod bundles under the stagnant condition were measured for a wide range of gas volume fluxes to examine the validity of available void correlations. Flow patterns were visualized by using a high-speed video camera to examine the effects of flow pattern on the void fraction. As a result, the following conclusions were obtained: (1) Dependence of the void fraction on the gas volume flux JG changed at JG ≅ 1.5 m/s due to the flow pattern transition. (2) Murase's correlation agreed well with the void fraction in the two kinds of rod bundles having different dimensions under the stagnant condition.

  10. Rod bundle thermal-hydraulic and melt progression analysis of CORA severe fuel damage experiments

    SciTech Connect

    Suh, K.Y. )

    1994-04-01

    An integral, fast-running computational model is developed to simulate the thermal-hydraulic and melt progression behavior in a nuclear reactor rod bundle under severe fuel damage conditions. This consists of the submodels for calculating steaming from the core, hydrogen formation, heat transfer in and out of the core, cooling from core spray or injection, and, most importantly, fuel melting, relocation, and freezing with chemical interactions taking place among the material constituents in a degrading core. The integral model is applied to three German severe fuel damage tests to analyze the core thermal and melt behavior: CORA-16 (18-rod bundle and slow cooling), CORA-17 (18-rod bundle and quenching), and CORA-18 (48-rod bundle and slow cooling). Results of the temperature response of the fuel rods, the channel box, and the absorber blade; hydrogen generation from the fuel rod and the channel box; and core material eutectic formation, melt relocation, and blockage formation are discussed. Reasonable agreement is observed for component temperatures at midelevation where prediction and measurement uncertainties are minimal. However, discrepancies or uncertainties are noticed for hydrogen generation and core-melt progression. The experimentally observed peak generation of hydrogen upon reflooding is not able to be reproduced, and the total amount generated is generally underpredicted primarily because of the early relocation of the Zircaloy fuel channel box and cladding. Also, difficulties are encountered in the process of assessing the core-melt formation and the relocation model because of either modeling uncertainties or a lack of definitive metallurgical data as a function of time throughout the transient.

  11. CFD analyses of flow structures in air-ingress and rod bundle problems

    NASA Astrophysics Data System (ADS)

    Wei, Hong-Chan

    Two topics from nuclear engineering field are included in this dissertation. One study is the air-ingress phenomenon during a loss of coolant accident (LOCA) scenario, and the other is a 5-by-5 bundle assembly with a PWR design. The objectives were to investigate the Kelvin-Helmholtz instability of the gravity-driven stratified flows inside a coaxial pipe and the effects caused by two types of spacers at the downstream of the rod bundle. Richardson extrapolation was used for the grid independent study. The simulation results show good agreements with the experiments. Wavelet analysis and Proper Orthogonal Decomposition (POD) were used to study the flow behaviors and flow patterns. For the air-ingress phenomenon, Brunt-Vaisala frequency, or buoyancy frequency, predicts a frequency of 2.34 Hz; this is confirmed by the dominant frequency of 2.4 Hz obtained from the wavelet analysis between times 1.2 s and 1.85 s. For the rod bundle study, the dominant frequency at the center of the subchannel was determined to be 2.4 Hz with a secondary dominant frequency of 4 Hz and a much minor frequency of 6 Hz. Generally, wavelet analysis has much better performance than POD, in the air-ingress phenomenon, for a strongly transient scenario; they are both appropriate for the rod bundle study. Based on this study, when the fluid pair in a real condition is used, the time which air intrudes into the reactor is predictable.

  12. RADGEN: A radiation exchange factor generator for rod bundles

    SciTech Connect

    Rector, D.R.

    1987-10-01

    The RADGEN computer program has been developed at Pacific Northwest Laboratory (PNL) to generate input required for the thermal radiation models used in the COBRA-SFS (Spent Fuel Storage) computer program. The COBRA-SFS program uses radiation exchange factors to describe the net amount of energy transferred from each surface to every other surface in an enclosure. The RADGEN program generates radiation exchange factors for arrays of rods on a square or triangular pitch as well as open channel geometries. This report describes the input requirements for the RADGEN code, which may be executed in a batch or interactive mode, and outlines the solution procedure used to obtain the exchange factors. 4 refs., 25 figs., 13 tabs.

  13. Two-phase flow interfacial structures in a rod bundle geometry

    NASA Astrophysics Data System (ADS)

    Paranjape, Sidharth S.

    Interfacial structure of air-water two-phase flow in a scaled nuclear reactor rod bundle geometry was studied in this research. Global and local flow regimes were obtained for the rod bundle geometry. Local two-phase flow parameters were measured at various axial locations in order to understand the transport of interfacial structures. A one-dimensional two-group interfacial area transport model was evaluated using the local parameter database. Air-water two-phase flow experiments were performed in an 8 X 8 rod bundle test section to obtain flow regime maps at various axial locations. Area averaged void fraction was measured using parallel plate type impedance void meters. The cumulative probability distribution functions of the signals from the impedance void meters were used along with a self organizing neural network to identify flow regimes. Local flow regime maps revealed the cross-sectional distribution of flow regimes in the bundle. Local parameters that characterize interfacial structure, that is, void fraction alpha, interfacial area concentration, ai, bubble Sauter mean diameter, DSm and bubble velocity, vg were measured using four sensor conductivity probe technique. The local data revealed the distribution of the interfacial structure in the radial direction, as well as its development in the axial direction. In addition to this, the effect of spacer grid on the flow structure at different gas and liquid velocities was revealed by local parameter measurements across the spacer grids. A two-group interfacial area transport equation (IATE) specific to rod bundle geometry was derived. The derivation of two-group IATE required certain assumption on the bubble shapes in the subchannels and the bubbles spanning more than a subchannel. It was found that the geometrical relationship between the volume and the area of a cap bubble distorted by rods was similar to the one derived for a confined channel under a specific geometrical transformation. The one

  14. CHF prediction of GE 3 x 3 rod bundle based on BODYFIT-2PE. [BWR

    SciTech Connect

    Chien, T.H.; Chen, B.C.J.; Sha, W.T.; Kim, J.H.

    1983-01-01

    A General Electric 3 x 3 rod bundle critical heat flux (CHF) experiment was analyzed by using BODYFIT-2PE. (Boundary-fitted coordinates-2 phase partially elliptic). BODYFIT-2PE is a three-dimensional, steady-state/transient, single-phase rod-bundle thermal-hydraulic computer program based on the technique of boudnary-fitted coordinate system. In this coordinate system, all the physical boundaries are made to be coincident with the coordinate lines so that the boundary conditions, such as constant heat fluxes and zero velocities, can be accurately represented without interpolation. However, the transformed coordinate system is not unique for a given geometric configuration. The more orthogonal the coordinates are, the faster the rates of calculational convergence. The generation of the transformed coordinates is based on the solution of a set of second-order partial differential equations, subject to a set of geometric boundary conditions. A simple Laplacian is used in the present study.

  15. Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

    SciTech Connect

    Krauss, T.; Meyer, L.

    1995-09-01

    Turbulent air flow in a wall sub-channel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. measurements were performed with hot-wire probe with X-wires and a temperature wire. The mean velocity, the mean fluid temperature, the wall shear stress and wall temperature, the turbulent quantities such as the turbulent kinetic energy, the Reynolds-stresses and the turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large scale periodic fluctuations are responsible for the high intersubchannel heat and momentum exchange.

  16. A thermal-hydraulic code for transient analysis in a channel with a rod bundle

    SciTech Connect

    Khodjaev, I.D.

    1995-09-01

    The paper contains the model of transient vapor-liquid flow in a channel with a rod bundle of core of a nuclear power plant. The computer code has been developed to predict dryout and post-dryout heat transfer in rod bundles of nuclear reactor core under loss-of-coolant accidents. Economizer, bubble, dispersed-annular and dispersed regimes are taken into account. The computer code provides a three-field representation of two-phase flow in the dispersed-annular regime. Continuous vapor, continuous liquid film and entrained liquid drops are three fields. For the description of dispersed flow regime two-temperatures and single-velocity model is used. Relative droplet motion is taken into account for the droplet-to-vapor heat transfer. The conservation equations for each of regimes are solved using an effective numerical technique. This technique makes it possible to determine distribution of the parameters of flows along the perimeter of fuel elements. Comparison of the calculated results with the experimental data shows that the computer code adequately describes complex processes in a channel with a rod bundle during accident.

  17. DESIGN OF WIRE-WRAPPED ROD BUNDLE MATCHED INDEX-OF-REFRACTION EXPERIMENTS

    SciTech Connect

    Hugh McIlroy; Hongbin Zhang; Kurt Hamman

    2008-05-01

    Experiments will be conducted in the Idaho National Laboratory (INL) Matched Index-of-Refraction (MIR) Flow Facility [1] to characterize the three-dimensional velocity and turbulence fields in a wire-wrapped rod bundle typically employed in liquid-metal cooled fast reactors and to provide benchmark data for computer code validation. Sodium cooled fast reactors are under consideration for use in the U.S. Department of Energy (DOE) Global Nuclear Energy Partnership (GNEP) program. The experiment model will be constructed of quartz components and the working fluid will be mineral oil. Accurate temperature control (to within 0.05 oC) matches the index-of-refraction of mineral oil with that of quartz and renders the model transparent to the wavelength of laser light employed for optical measurements. The model will be a scaled 7-pin rod bundle enclosed in a hexagonal canister. Flow field measurements will be obtained with a LaVision 3-D particle image velocimeter (PIV) and complimented by near-wall velocity measurements obtained from a 2-D laser Doppler velocimeter (LDV). These measurements will be used as benchmark data for computational fluid dynamics (CFD) validation. The rod bundle model dimensions will be scaled up from the typical dimensions of a fast reactor fuel assembly to provide the maximum Reynolds number achievable in the MIR flow loop. A range of flows from laminar to fully-turbulent will be available with a maximum Reynolds number, based on bundle hydraulic diameter, of approximately 22,000. The fuel pins will be simulated by 85 mm diameter quartz tubes (closed on the inlet ends) and the wire-wrap will be simulated by 25 mm diameter quartz rods. The canister walls will be constructed from quartz plates. The model will be approximately 2.13 m in length. Bundle pressure losses will also be measured and the data recorded for code comparisons. The experiment design and preliminary CFD calculations, which will be used to provide qualitative hydrodynamic

  18. The Annular Two-phase Flow on Rod Bundle: The Effects of Spacers

    NASA Astrophysics Data System (ADS)

    Kunugi, Tomoaki; Pham, Son; Kawara, Zensaku; Yokomine, Takehiko

    2013-11-01

    The annular two-phase flow on rod bundle keeps an important role in many heat exchange systems but our knowledge about it, especially the interaction between the liquid film flowing on the rods' surfaces and the spacers is very limited. This study is aimed to the investigation of how the spacer affects the disturbance waves of the flow in a 3 × 3 simulating BWR fuel rod bundle test section. Firstly, the characteristics of the disturbance waves at both upstream and downstream locations of the spacer were obtained by using reflected light arrangement with a high speed camera Phantom V7.1 (Vision Research Inc.) and a Nikon macro lens 105mm f/2.8. The data showed that the parameters such as frequency and circumferential coherence of the disturbance waves are strongly modified when they go through the spacer. Then, the observations at the locations right before and after the spacer were performed by using the back light arrangement with the same high speed camera and a Cassegrain optical system (Seika Cooperation). The obtained images at micro-scale of time and space provided the descriptions of the wavy interface behaviors right before and after the spacer as well as different droplets creation processes caused by the presence of this spacer.

  19. CFD study of isothermal water flow in rod bundle with split-type spacer grid

    NASA Astrophysics Data System (ADS)

    Batta, A.; Class, A. G.

    2014-06-01

    The design of rod bundles in nuclear application nowadays is assessed by CFD (computational fluid dynamics). The accuracy of CFD models need validation. Within the OECD/NEA benchmark MATiS-H (Measurement and Analysis of Turbulent Mixing in Sub-channels - Horizontal) a single-phase water flow in a 5x5 rod bundle is studied. In the benchmark, two types of spacer grids are tested, the swirl type and the split type, where the current study focuses on the split type spacer grid. Comparison of CFD results obtained at Karlsruhe Institut of Technology (KIT) with experimental results of KAERI (Korea Atomic Energy Research Institute) are presented. In the benchmark velocities components along selected lines downstream of the spacer grid are measured and compared to CFD results. The CFD code STAR CCM+ with the Realized k-ɛ model is used. Comparisons with experimental results show quantitative and qualitative agreement for the averaged values of velocity components. Comparisons of results to other benchmark partners using different modeling show that the selected mesh size and models for the analysis of the current case gives relatively accurate results. However, the used turbulent model (Realized k-ɛ does not capture the turbulent intensity correctly. Computation shows that the flow has very high mixing due to the spacer grid, which does not decay within the measurements domain (z/ DH =0-10 downstream of spacer grid). The same conclusion can be drawn from experimental data.

  20. Reflooding and boil-off experiments in a VVER-440 like rod bundle and analyses with the CATHARE code

    SciTech Connect

    Korteniemi, V.; Haapalehto, T.; Puustinen, M.

    1995-09-01

    Several experiments were performed with the VEERA facility to simulate reflooding and boil-off phenomena in a VVER-440 like rod bundle. The objective of these experiments was to get experience of a full-scale bundle behavior and to create a database for verification of VVER type core models used with modern thermal-hydraulic codes. The VEERA facility used in the experiments is a scaled-down model of the Russian VVER-440 type pressurized water reactors used in Loviisa, Finland. The test section of the facility consists of one full-scale copy of a VVER-440 reactor rod bundle with 126 full-length electrically heated rod simulators. Bottom and top-down reflooding, different modes of emergency core cooling (ECC) injection and the effect of heating power on the heat-up of the rods was studied. In this paper the results of calculations simulating two reflood and one boil-off experiment with the French CATHARE2 thermal-hydraulic code are also presented. Especially the performance of the recently implemented top-down reflood model of the code was studied.

  1. Development of Design Technology on Thermal-Hydraulic Performance in Tight-Lattice Rod Bundles: II - Rod Bowing Effect on Boiling Transition under Transient Conditions

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Tamai, Hidesada; Kureta, Masatoshi; Ohnuki, Akira; Akimoto, Hajime

    A thermal-hydraulic feasibility project for an Innovative Water Reactor for Flexible fuel cycle (FLWR) has been performed since 2002. In this R&D project, large-scale thermal-hydraulic tests, several model experiments and development of advanced numerical analysis codes have been carried out. In this paper, we describe the critical power characteristics in a 37-rod tight-lattice bundle with rod bowing under transient states. It is observed that transient Boiling Transition (BT) always occurs axially at exit elevation of upper high-heat-flux region and transversely in the central area of the bundle, which is same as that under steady state. For the postulated power increase and flow decrease cases that may be possibly met in a normal operation of the FLWR, it is confirmed that no BT occurs when Initial Critical Power Ratio (ICPR) is 1.3. Moreover, when the transients are run under severer ICPR that causes BT, the transient critical powers are generally same as the steady ones. The experiments are analyzed with a modified TRAC-BFI code, where Japan Atomic Energy Agency (JAEA) newest critical power correlation is implemented for the BT judgement. The code shows good prediction for the occurrence or the non occurrence of the BT and predicts the BT starting time conservatively. Traditional quasi-steady state prediction of the transient BT is confirmed being applicable for the postulated abnormal transient processes in the tight-lattice bundle with rod bowing.

  2. Rod-bundle transient-film boiling of high-pressure water in the liquid-deficient regime. [PWR

    SciTech Connect

    Morris, D.G.; Mullins, C.B.; Yoder, G.L.

    1982-01-01

    Results are reported from a recent experiment investigating dispersed flow film boiling of high pressure water in upflow through a rod bundle. The data, obtained under mildly transient conditions, are used to assess correlations currently used to predict heat transfer in these circumstances. In light of the scarcity of similar data, the data should prove useful in the development and assessment of new heat transfer models. The experiment was conducted at the Oak Ridge National Laboratory in the Thermal-Hydraulic Test Facility, a highly instrumented, non-nuclear, pressurized-water loop containing 64, 3.66-m (12-ft) long rods (of which 60 are electrically heated). The rods are arranged in a square array typical of 17 x 17 fuel rod assemblies in late generation PWRs. Data were collected over typical reactor blowdown parameter ranges.

  3. Numerical Simulation of Boiling Two-Phase Flow in Tight-Lattice Rod Bundle by 3-Dimensional Two-Fluid Model Code ACE-3D

    NASA Astrophysics Data System (ADS)

    Yoshida, Hiroyuki; Misawa, Takeharu; Takase, Kazuyuki

    Two-fluid model can simulate two-phase flow by computational cost less than detailed two-phase flow simulation method such as interface tracking method or particle interaction method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as a rod bundle. Japan Atomic Energy Agency (JAEA) develops three dimensional two-fluid model analysis code ACE-3D that adopts boundary fitted coordinate system in order to simulate complex shape flow channel. In this paper, boiling two-phase flow analysis in a tight-lattice rod bundle was performed by ACE-3D code. The parallel computation using 126 CPUs was applied to this analysis. In the results, the void fraction, which distributes in outermost region of rod bundle, is lower than that in center region of rod bundle. The tendency of void fraction distribution agreed with the measurement results by neutron radiography qualitatively. To evaluate effects of two-phase flow model used in ACE-3D code, numerical simulation of boiling two-phase in tight-lattice rod bundle with no lift force model was also performed. From the comparison of calculated results, it was concluded that the effects of lift force model were not so large for overall void fraction distribution of tight-lattice rod bundle. However, the lift force model is important for local void fraction distribution of fuel bundles.

  4. Electrostatics and depletion determine competition between 2D nematic and 3D bundled phases of rod-like DNA nanotubes.

    PubMed

    Park, Chang-Young; Fygenson, Deborah K; Saleh, Omar A

    2016-06-21

    Rod-like particles form solutions of technological and biological importance. In particular, biofilaments such as actin and microtubules are known to form a variety of phases, both in vivo and in vitro, whose appearance can be controlled by depletion, confinement, and electrostatic interactions. Here, we utilize DNA nanotubes to undertake a comprehensive study of the effects of those interactions on two particular rod-like phases: a 2D nematic phase consisting of aligned rods pressed against a glass surface, and a 3D bundled network phase. We experimentally measure the stability of these two phases over a range of depletant concentrations and ionic strengths, finding that the 2D phase is slightly more stable than the 3D phase. We formulate a quantitative model of phase stability based on consideration of pairwise rod-rod and rod-surface interactions; notably, we include a careful accounting of solution electrostatics interactions using an effective-charge strategy. The model is relatively simple and contains no free parameters, yet predicts phase boundaries in good agreement with the experiment. Our results indicate that electrostatic interactions, rather than depletion, are largely responsible for the enhanced stability of the 2D phase. This work provides insight into the polymorphism of rod-like solutions, indicating why certain phases appear, and providing a means (and a predictive model) for controlling those phases. PMID:27126684

  5. Scale resolving simulations of the water flow through a rod bundle with split-type spacer grid

    NASA Astrophysics Data System (ADS)

    Matyushenko, A. A.; Garbaruk, A. V.

    2014-12-01

    Unsteady isothermal turbulent flow in periodic sub-channel of 5×5 rod bundle with split-type spacer grid is investigated using modern Scale Resolving Simulation methods: Wall Modelling Large Eddy Simulation (WMLES) and Scale Adapting Simulation (SAS). Solutions obtained with both methods show complicated swirling flow dissipating over the distance from spacer grid and are in a good agreement with the experimental data except an area in close vicinity of the vanes.

  6. PWR FLECHT SEASET 163-Rod Bundle Flow Blockage Task data report. NRC/EPRI/Westinghouse report No. 13, August-October 1982

    SciTech Connect

    Loftus, M J; Hochreiter, L E; McGuire, M F; Valkovic, M M

    1983-10-01

    This report presents data from the 163-Rod Bundle Blow Blockage Task of the Full-Length Emergency Cooling Heat Transfer Systems Effects and Separate Effects Test Program (FLECHT SEASET). The task consisted of forced and gravity reflooding tests utilizing electrical heater rods with a cosine axial power profile to simulate PWR nuclear core fuel rod arrays. These tests were designed to determine effects of flow blockage and flow bypass on reflooding behavior and to aid in the assessment of computational models in predicting the reflooding behavior of flow blockage in rod bundle arrays.

  7. Numerical Investigation of Cross Flow Phenomena in a Tight-Lattice Rod Bundle Using Advanced Interface Tracking Method

    NASA Astrophysics Data System (ADS)

    Zhang, Weizhong; Yoshida, Hiroyuki; Ose, Yasuo; Ohnuki, Akira; Akimoto, Hajime; Hotta, Akitoshi; Fujimura, Ken

    In relation to the design of an innovative FLexible-fuel-cycle Water Reactor (FLWR), investigation of thermal-hydraulic performance in tight-lattice rod bundles of the FLWR is being carried out at Japan Atomic Energy Agency (JAEA). The FLWR core adopts a tight triangular lattice arrangement with about 1 mm gap clearance between adjacent fuel rods. In view of importance of accurate prediction of cross flow between subchannels in the evaluation of the boiling transition (BT) in the FLWR core, this study presents a statistical evaluation of numerical simulation results obtained by a detailed two-phase flow simulation code, TPFIT, which employs an advanced interface tracking method. In order to clarify mechanisms of cross flow in such tight lattice rod bundles, the TPFIT is applied to simulate water-steam two-phase flow in two modeled subchannels. Attention is focused on instantaneous fluctuation characteristics of cross flow. With the calculation of correlation coefficients between differential pressure and gas/liquid mixing coefficients, time scales of cross flow are evaluated, and effects of mixing section length, flow pattern and gap spacing on correlation coefficients are investigated. Differences in mechanism between gas and liquid cross flows are pointed out.

  8. Investigation of combined free and forced convection in a 2 x 6 rod bundle during controlled flow transients

    SciTech Connect

    Bates, J.M.; Khan, E.U.

    1980-10-01

    An experimental study was performed to obtain local fluid velocity and temperature measurements in the mixed (combined free and forced) convection regime for specific flow coastdown transients. A brief investigation of steady-state flows for the purely free-convection regime was also completed. The study was performed using an electrically heated 2 x 6 rod bundle contained in a flow housing. In addition a transient data base was obtained for evaluating the COBRA-WC thermal-hydraulic computer program (a modified version of the COBRA-IV code).

  9. Laboratory manual for static pressure drop experiments in LMFBR wire wrapped rod bundles

    SciTech Connect

    Burns, K.J.; Todreas, N.E.

    1980-07-01

    Purpose of this experiment is to determine both interior and edge subchannel axial pressure drops for a range of Reynolds numbers. The subchannel static pressure drop is used to calculate subchannel and bundle average friction factors, which can be used to verify existing friction factor correlations. The correlations for subchannel friction factors are used as input to computer codes which solve the coupled energy, continuity, and momentum equations, and are also used to develop flow split correlations which are needed as input to codes which solve only the energy equation. The bundle average friction factor is used to calculate the overall bundle pressure drop, which determines the required pumping power.

  10. Irradiation performance of long-rod duplex fuel-pellet bundle test - LDR test (AWBA Development Program)

    SciTech Connect

    Waldman, L.A.; Sphar, C.D.; Alff, T.H.

    1982-04-01

    The Long Duplex Rod (LDR) test is a five-rod bundle irradiation test of 0.30-inch diameter, 8-foot long, Zircaloy-clad rods containing duplex fuel pellets. These pellets include fissile material in an outer annulus surrounding fertile material in an inner cylindrical core. The rods are axially supported by top or bottom base plates and are laterally supported by an AM-350 stainless steel grid system. Design of the test, which includes duplex pellet annuli of three different compositions (UO/sub 2/, ZrO/sub 2/-UO/sub 2/-CaO, and ThO/sub 2/-UO/sub 2/), is described; and results of nondestructive examination after operation at peak linear power output of 9 to 18 Kw/ft to a peak depletion of 15 x 10/sup 20/ fissions/cm/sup 3/ of compartment (6.0 x 10/sup 4/ MWD/Tonne U + Th), or 30 x 10/sup 20/ fissions/cm/sup 3/ of fuel annulus volume (1.2 x 10/sup 5/ MWD/Tonne U + Th), are presented. It is concluded that performance capability of the duplex pellets is satisfactory for use in prebreeder reactor cores.

  11. Calculation of Inter-Subchannel Turbulent Mixing Rate and Heat Transfer in a Triangular-Arrayed Rod Bundle Using Direct Numerical Simulation

    SciTech Connect

    Yudov, Yury V.

    2006-07-01

    The direct numerical simulation, extended to boundary - fitted coordinate, has been carried out for a fully-developed turbulent flow thermal hydraulics in a triangular rod bundle. The rod bundle is premised to be an infinite array. The spacer grid effects are ignored. The purpose of this work is to verify DNS methodology to be applied for deriving coefficients for inter-subchannel turbulent mixing and heat transfer on a rod. These coefficients are incorporated in subchannel analysis codes. To demonstrate the validity of this methodology, numerical calculation was performed for the bundle with the pitch to diameter ratio 1.2, at friction Reynolds number of 600 and Prandtl number of 1. The results for the hydraulic parameters are compared with published DNS data, and the results for the heat exchange coefficients -- with those obtained using semi-empirical correlations. (authors)

  12. Coolant mixing in LMFBR rod bundles and outlet plenum mixing transients. Final report

    SciTech Connect

    Todreas, N.E.; Cheng, S.K.; Basehore, K.

    1984-08-01

    This project principally undertook the investigation of the thermal hydraulic performance of wire wrapped fuel bundles of LMFBR configuration. Results obtained included phenomenological models for friction factors, flow split and mixing characteristics; correlations for predicting these characteristics suitable for insertion in design codes; numerical codes for analyzing bundle behavior both of the lumped subchannel and distributed parameter categories and experimental techniques for pressure velocity, flow split, salt conductivity and temperature measurement in water cooled mockups of bundles and subchannels. Flow regimes investigated included laminar, transition and turbulent flow under forced convection and mixed convection conditions. Forced convections conditions were emphasized. Continuing efforts are underway at MIT to complete the investigation of the mixed convection regime initiated here. A number of investigations on outlet plenum behavior were also made. The reports of these investigations are identified.

  13. PWR FLECHT SEASET 21-rod bundle flow blockage task data and analysis report. NRC/EPRI/Westinghouse Report No. 11. Appendices K-P

    SciTech Connect

    Loftus, M.J.; Hochreiter, L.E.; Lee, N.; McGuire, M.F.; Wenzel, A.H.; Valkovic, M.M.

    1982-09-01

    This report presents data and limited analysis from the 21-Rod Bundle Flow Blockage Task of the Full-Length Emergency Cooling Heat Transfer Separate Effects and Systems Effects Test Program (FLECHT SEASET). The tests consisted of forced and gravity reflooding tests utilizing electrical heater rods with a cosine axial power profile to simulate PWR nuclear core fuel rod arrays. Steam cooling and hydraulic characteristics tests were also conducted. These tests were utilized to determine effects of various flow blockage configurations (shapes and distributions) on reflooding behavior, to aid in development/assessment of computational models in predicting reflooding behavior of flow blockage configurations, and to screen flow blockage configurations for future 163-rod flow blockage bundle tests.

  14. Fluid-mixing studies in a hexagonal 217-pin wire-wrapped rod bundle. [LMFBR

    SciTech Connect

    Symolon, P.D.; Todreas, N.E.

    1981-02-01

    Mixing, pressure drop, and flow split experiments were performed on a 217 pin LMFBR fuel bundle with a pitch to diameter ratio of 1.25 and a lead length of 12 inches. It was found that the turbulent flow data could best be characterized by the energy parameter C/sub 1L/=.106, which is 9% higher than the value from the correlation of Chiu et al. Chiu's correlation was developed on a data base of 61 and 91 pins. The spread of existing data about the correlation is +- 25%, but the error band on our data is expected to be less (approx. +- 10% since injection depth effects were not previously considered). This result is consistent with the concept of increased swirl flow in larger bundles (more pins).

  15. Assessment of Biasi and Columbia University CHF correlations with GE 3x3 rod bundle experiment. [PWR; BWR

    SciTech Connect

    Chen, B.C.J.; Chien, T.H.; Sha, W.T.; Kim, J.H.

    1984-01-01

    The critical heat flux (CHF), at which a sudden degradation of heat transfer occurs without corresponding decrease in heat generation, is one of the limiting parameters for safe operation of nuclear reactors. Reactor operation beyond the CHF causes a rapid rise in fuel cladding temperature and thus should be avoided to maintain the fuel element integrity. Reactor power limits are therefore set so that a prescribed safety margin below the CHF is maintained. Two CHF correlations are evaluated for reactor core thermal hydraulic analysis: the Biasi correlation and the Columbia University correlation. The BODYFIT-2PE computer code is used for this assessment. The CHF predicted by the BODYFIT-2PE using the two correlations is compared with GE 3x3 rod bundle CHF experiment.

  16. Finite element solution of axial turbulent flow in a bare rod bundle using a one-equation turbulence model

    SciTech Connect

    Slagter, W.

    1982-11-01

    A new form of the one-equation turbulence model has been developed and verified by application to fully developed turbulent flow in smooth, bare rod bundles. The present model allows for the effect of anisotropic eddy viscosities on turbulent flow quantities. The finite element method has been used to predict local values of velocity and turbulent kinetic energy right up to the wall. A variational principle is applied to develop the finite element relationships. The resulting set of nonlinear algebraic equations for the nodal parameters is linearized by the successive-substitution scheme and solved by the frontal solution technique. The numerical results are shown to be in good agreement with available experimental data.

  17. Stability analysis of a square rod bundle sub-channel in supercritical water reactor

    NASA Astrophysics Data System (ADS)

    Hai-jun, Wang; Ting, You; Lei, Zhang; Hong-fang, Gu; Yu-shan, Luo; Ji-lian, Bian

    2013-07-01

    Extensive investigations on the flow and heat transfer behavior in SCWR fuel assembly have been undertaken worldwide. However, stability analysis of supercritical water in the sub-channels of tight lattices is still lacking. In this paper, the flow stability of a fuel bundle channel with square pitches has been analyzed using commercial CFD code-ANSYS Fluent. Typical dynamic instability of Density Wave Oscillation (DWO) has occurred in heated channel containing fluids at supercritical pressure. A further discussion about the impacts of various operational parameters (e.g. power input, system pressure, mass velocity, inlet temperature, etc) shows that the system becomes more stable as system pressure and/or mass flow rate increases. An increase in inlet temperature also has a stabilizing effect on the system.

  18. Dispersed-flow film boiling in rod-bundle geometry: steady-state heat-transfer data and correlation comparisons. [PWR; BWR

    SciTech Connect

    Yoder, G. L.; Morris, D. G.; Mullins, C. B.; Ott, L. J.; Reed, D. A.

    1982-03-01

    Assessment of six film boiling correlations and one single-phase vapor correlation has been made using data from 22 steady state upflow rod bundle tests (series 3.07.9). Bundle fluid conditions were calculated using energy and mass conservation considerations. Results of the steady state film boiling tests support the conclusions reached in the analysis of prior transient tests 3.03.6AR, 3.06.6B, and 3.08.6C. Comparisons between experimentally determined and correlation-predicted heat transfer coefficients, are presented.

  19. GMDH-type neural network modeling and genetic algorithm-based multi-objective optimization of thermal and friction characteristics in heat exchanger tubes with wire-rod bundles

    NASA Astrophysics Data System (ADS)

    Rahimi, Masoud; Beigzadeh, Reza; Parvizi, Mehdi; Eiamsa-ard, Smith

    2016-08-01

    The group method of data handling (GMDH) technique was used to predict heat transfer and friction characteristics in heat exchanger tubes equipped with wire-rod bundles. Nusselt number and friction factor were determined as functions of wire-rod bundle geometric parameters and Reynolds number. The performance of the developed GMDH-type neural networks was found to be superior in comparison with the proposed empirical correlations. For optimization, the genetic algorithm-based multi-objective optimization was applied.

  20. PWR FLECHT SEASET 21-rod-bundle flow-blockage task: data and analysis report. NRC/EPRI/Westinghouse report No. 11, main report and appendices A-J

    SciTech Connect

    Loftus, M.J.; Hochreiter, L.E.; Lee, N.; McGuire, M.F.; Wenzel, A.H.; Valkovic, M.M.

    1982-09-01

    This report presents data and limited analysis from the 21-Rod Bundle Flow Blockage Task of the Full-Length Emergency Cooling Heat Transfer Separate Effects and Systems Effects Test Program (FLECHT SEASET). The tests consisted of forced and gravity reflooding tests utilizing electrical heater rods with a cosine axial power profile to simulate PWR nuclear core fuel rod arrays. Steam cooling and hydraulic characteristics tests were also conducted. These tests were utilized to determine effects of various flow blockage configurations (shapes and distributions) on reflooding behavior, to aid in development/assessment of computational models in predicting reflooding behavior of flow blockage configurations, and to screen flow blockage configurations for future 163-rod flow blockage bundle tests.

  1. Assessment of CCFL model of RELAP5/MOD3 against simple vertical tubes and rod bundle tests. International Agreement Report

    SciTech Connect

    Cho, S.; Arne, N.; Chung, B.D.; Kim, H.J.

    1993-06-01

    The CCFL model used in RELAP5/MOD3 version 5m5 has been assessed against simple vertical tubes and bundle tests performed at a facility of Korea Atomic Energy Research Institute. The effect of changes in tube diameter and nodalization of tube section were investigated. The roles of interfacial drags on the flooding characteristics are discussed. Differences between the calculation and the experiment are also discussed. A comparison between model assessment results and the test data showed that the calculated value lay well on the experimental flooding curve specified by user, but the pressure jump before onset of flooding was not calculated.

  2. ORNL rod-bundle heat-transfer test data. Volume 6. Thermal-hydraulic test facility experimental data report for test 3. 05. 5B - double-ended cold-leg break simulation

    SciTech Connect

    Mullins, C.B.; Felde, D.K.; Sutton, A.G.; Gould, S.S.; Morris, D.G.; Robinson, J.J.; Schwinkendorf, K.N.

    1982-05-18

    Thermal-Hydraulic Test Facility (THTF) Test 3.05.5B was conducted by members of the ORNL PWR Blowdown Heat Transfer Separate-Effects Program on July 3, 1980. The objective of the program is to investigate heat transfer phenomena believed to occur in PWRs during accidents, including small and large break loss-of-coolant accidents. Test 3.05.5B was designed to provide transient thermal-hydraulics data in rod bundle geometry under reactor accident-type conditions. Reduced instrument responses are presented. Also included are uncertainties in the instrument responses, calculated mass flows, and calculated rod powers.

  3. BODYFIT-1FE: a computer code for three-dimensional steady-state/transient single-phase rod-bundle thermal-hydraulic analysis. Draft report

    SciTech Connect

    Chen, B.C.J.; Sha, W.T.; Doria, M.L.; Schmitt, R.C.; Thompson, J.F.

    1980-11-01

    The governing equations, i.e., conservation equations for mass, momentum, and energy, are solved as a boundary-value problem in space and an initial-value problem in time. BODYFIT-1FE code uses the technique of boundary-fitted coordinate systems where all the physical boundaries are transformed to be coincident with constant coordinate lines in the transformed space. By using this technique, one can prescribe boundary conditions accurately without interpolation. The transformed governing equations in terms of the boundary-fitted coordinates are then solved by using implicit cell-by-cell procedure with a choice of either central or upwind convective derivatives. It is a true benchmark rod-bundle code without invoking any assumptions in the case of laminar flow. However, for turbulent flow, some empiricism must be employed due to the closure problem of turbulence modeling. The detailed velocity and temperature distributions calculated from the code can be used to benchmark and calibrate empirical coefficients employed in subchannel codes and porous-medium analyses.

  4. COBRA-IV PC: A personal computer version of COBRA-IV-I for thermal-hydraulic analysis of rod bundle nuclear fuel elements and cores

    SciTech Connect

    Webb, B.J.

    1988-01-01

    COBRA-IV PC is a modified version of COBRA-IV-I, adapted for use with most IBM PC and PC-compatible desktop computers. Like COBRA-IV-I, COBRA-IV PC uses the subchannel analysis approach to determine the enthalpy and flow distribution in rod bundles for both steady-state and transient conditions. The steady-state and transient solution schemes used in COBRA-IIIC are still available in COBRA-IV PC as the implicit solution scheme option. An explicit solution scheme is also available, allowing the calculation of severe transients involving flow reversals, recirculations, expulsions, and reentry flows, with a pressure or flow boundary condition specified. In addition, several modifications have been incorporated into COBRA-IV PC to allow the code to run on the PC. These include a reduction in the array dimensions, the removal of the dump and restart options, and the inclusion of several code modifications by Oregon State University, most notably, a critical heat flux correlation for boiling water reactor fuel and a new solution scheme for cross-flow distribution calculations. 7 refs., 8 figs., 1 tab.

  5. ORNL rod-bundle heat-transfer test data. Volume 7. Thermal-Hydraulic Test Facility experimental data report for test series 3. 07. 9 - steady-state film boiling in upflow

    SciTech Connect

    Mullins, C.B.; Felde, D.K.; Sutton, A.G.; Gould, S.S.; Morris, D.G.; Robinson, J.J.

    1982-05-01

    Thermal-Hydraulic Test Facility (THTF) test series 3.07.9 was conducted by members of the Oak Ridge National Laboratory Pressurized-Water Reactor (ORNL-PWR) Blowdown Heat Transfer (BDHT) Separate-Effects Program on September 11, September 18, and October 1, 1980. The objective of the program is to investigate heat transfer phenomena believed to occur in PWRs during accidents, including small- and large-break loss-of-coolant accidents. Test series 3.07.9 was designed to provide steady-state film boiling data in rod bundle geometry under reactor accident-type conditions. This report presents the reduced instrument responses for THTF test series 3.07.9. Also included are uncertainties in the instrument responses, calculated mass flows, and calculated rod powers.

  6. ORNL rod-bundle heat-transfer test data. Volume 3. Thermal-hydraulic test facility experimental data report for test 3. 06. 6B - transient film boiling in upflow. [PWR

    SciTech Connect

    Mullins, C.B.; Felde, D.K.; Sutton, A.G.; Gould, S.S.; Morris, D.G.; Robinson, J.J.

    1982-05-01

    Reduced instrument responses are presented for Thermal-Hyraulic Test Facility (THTF) Test 3.06.6B. This test was conducted by members of the Oak Ridge National Laboratory Pressurized-Water-Reactor (PWR) Blowdown Heat Transfer (BDHT) Separate-Effects Program on August 29, 1980. The objective of the program was to investigate heat transfer phenomena believed to occur in PWR's during accidents, including small and large break loss-of-coolant accidents. Test 3.06.6B was conducted to obtain transient film boiling data in rod bundle geometry under reactor accident-type conditions. The primary purpose of this report is to make the reduced instrument responses for THTF Test 3.06.6B available. Included in the report are uncertainties in the instrument responses, calculated mass flows, and calculated rod powers.

  7. Heat and mass transfer in turbulent flow of the N/sub 2/O/sub 4/ /r reversible/ 2NO/sub 2/ /r reversible/ 2NO + O/sub 2/ system in a rod bundle contained in a hexagonal jacket

    SciTech Connect

    Besedina, T.V.; Tverkovkin, B.E.; Udot, A.V.; Yakushev, A.P.

    1988-08-01

    A model is proposed for heat and mass transfer in a flowing dissociating liquid coolant in a nuclear fuel rod bundle in a hexagonal jacket. The temperature pattern in the liquid and in a heat-conducting rod was determined from general solutions to the conduction equations for rods and shells. Calculations are specifically constructed for determining the longitudinal flow and heat transfer of a N/sub 2//sub 4/ coolant in the peripheral (lateral and corner) channels of the rod groups. The turbulent transfer coefficients were calculated from Buleev's model. The finite-element method was used to derive unknown quantities of the velocity and temperature. Expressions were also found for modeling heat transfer in the frozen and chemically reacting flow components of the coolant. The algorithm is intended for reducing the temperature nonuniformity in parametric fuel rod bundle design calculations.

  8. Studies on sodium boiling phenomena in out of pile rod bundles for various accidental situations in Liquid Metal Fast Breeder Reactors (LMFBR) experiments and interpretations

    NASA Astrophysics Data System (ADS)

    Seiler, J. M.; Rameau, B.

    Bundle sodium boiling in nominal geometry for different accident conditions is reviewed. Voiding of a subassembly is controlled by not only hydrodynamic effects but mainly by thermal effects. There is a strong influence of the thermal inertia of the bundle material compared to the sodium thermal inertia. Flow instability, during a slow transient, can be analyzed with numerical tools and estimated using simplified approximations. Stable boiling operational conditions under bundle mixed convection (natural convection in the reactor) can be predicted. Voiding during a fast transient can be approximated from single channel calculations. The phenomenology of boiling behavior for a subassembly with inlet completely blocked, submitted to decay heat and lateral cooling; two-phase sodium flow pressure drop in a tube of large hydraulic diameter under adiabatic conditions; critical flow phenomena and voiding rate under high power, slow transient conditions; and onset of dry out under local boiling remains problematical.

  9. Fuel bundle design for enhanced usage of plutonium fuel

    DOEpatents

    Reese, Anthony P.; Stachowski, Russell E.

    1995-01-01

    A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced.

  10. End-of-life nondestructive examination of Light Water Breeder Reactor fuel rods (LWBR Development Program)

    SciTech Connect

    Gorscak, D.A.; Campbell, W.R.; Clayton, J.C.

    1987-10-01

    In-bundle and out-of-bundle (single rod) nondestructive examinations of Light Water Breeder Reactor fuel rods were performed. In-bundle examinations included visual examination and measurement of rod bow, rod-to-rod gaps, and rod removal forces. Out-of-bundle examinations included rod visuals and measurement of fuel rod length, diameter and ovality, cladding oxide and crud thickness, support grid induced cladding wear mark depth and volume, and fuel rod free hanging bow. The out-of-bundle examination also included ultrasonic inspection for cladding defects, neutron radiography for pellet integrity and plenum gap measurements, and gamma scans for instack axial gap screening and binary fuel stack length measurements. The measurements confirmed design predictions of fuel rod performance and provided evidence of excellent fuel rod performance for operation of Light Water Breeder Reactor to 29,047 effective full power hours (EFPH).

  11. Fuel bundle design for enhanced usage of plutonium fuel

    DOEpatents

    Reese, A.P.; Stachowski, R.E.

    1995-08-08

    A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced. 10 figs.

  12. Rodding Surgery

    MedlinePlus

    ... Rods can be made of stainless steel or titanium. Regular rods do not expand. They have many ... v regular), the rod materials (stainless steel v titanium) and the age for a first rodding surgery. ...

  13. Hydraulic reinforcement of channel at lower tie-plate in BWR fuel bundle

    SciTech Connect

    Johansson, E.B.

    1989-12-26

    This patent describes an apparatus in a fuel bundle for confining fuel rods for the generation of steam in a steam water mixture passing interior of the fuel bundle. The fuel bundle includes: a lower tie-plate for supporting the fuel rods and permitting flow from the lower exterior portion of the fuel bundle into the interior portion of the fuel bundle; a plurality of fuel rods. The fuel rods supported on the lower tie-plate extending upwardly to and towards the upper portion of the fuel bundle for the generation of steam in a passing steam and water mixture interior of the fuel bundle; an upper tie-plate for maintaining the fuel rods in side-by-side relation and permitting a threaded connection between a plurality of the fuel rods with the threaded connection being at the upper and lower tie-plate. The upper tie-plate permitting escape of a steam water mixture from the top of the fuel bundle; a fuel bundle channel; and a labyrinth seal configured in the lower tie-plate.

  14. German bundle shear - cold test results

    SciTech Connect

    Kunze, P.

    1986-01-01

    In the planned Federal Republic of Germany (FRG) reprocessing plant, the mechanical decladding of the fuel elements will be done with a bundle shear. This shear was designed and built with Thyssen Henschel by adapting the experiences of the Wiederaufarbeitungsanlage Karlsruhe (WAK), the FRG reprocessing pilot plant. The tests included boiling water reactor (BWR) and pressurized water reactor (PWR) dummy elements filled with porcelain as well as steel fuel rod simulators. During the test period with prototype bundle shear, some technical improvements have been found that refer both to operating conditions and to remote handling. In 1987 the acceptance tests will be run.

  15. His bundle electrography

    MedlinePlus

    ... can be given medicines during the test. Electrocardiogram (ECG) leads are placed on your arms and legs. ... HBE; His bundle recording; Electrogram - His bundle Images ECG References Miller JM, Zipes DP. Diagnosis of cardiac ...

  16. Hydrodynamic interaction of bacterial flagella - flagellar bundling

    NASA Astrophysics Data System (ADS)

    Lim, Sookkyung

    2013-11-01

    Flagellar bundling is an important aspect of locomotion in bacteria such as Escherichia coli. To study the hydrodynamic behavior of helical flagella, we present a computational model that is based on the geometry of the bacterial flagellar filament at the micrometer scale. We consider two model flagella, each of which has a rotary motor at its base with the rotation rate of the motor set at 100 Hz. Bundling occurs when both flagella are left-handed helices turning counterclockwise (when viewed from the nonmotor end of the flagellum looking back toward the motor) or when both flagella are right-handed helices turning clockwise. Helical flagella of the other combinations of handedness and rotation direction do not bundle. In this work we use the generalized immersed boundary method combined with the unconstrained Kirchhoff rod theory, which allows us to study the complicated hydrodynamics of flagellar behavior. This is a joint work with Charlie Peskin at NYU. NSF

  17. Control rods in LMFBRs: a physics assessment

    SciTech Connect

    McFarlane, H.F.; Collins, P.J.

    1982-08-01

    This physics assessment is based on roughly 300 control rod worth measurements in ZPPR from 1972 to 1981. All ZPPR assemblies simulated mixed-oxide LMFBRs, representing sizes of 350, 700, and 900 MWe. Control rod worth measurements included single rods, various combinations of rods, and Ta and Eu rods. Additional measurements studied variations in B/sub 4/C enrichment, rod interaction effects, variations in rod geometry, neutron streaming in sodium-filled channels, and axial worth profiles. Analyses were done with design-equivalent methods, using ENDF/B Version IV data. Some computations for the sensitivities to approximations in the methods have been included. Comparisons of these analyses with the experiments have allowed the status of control rod physics in the US to be clearly defined.

  18. On the perfect hexagonal packing of rods

    NASA Astrophysics Data System (ADS)

    Starostin, E. L.

    2006-04-01

    In most cases the hexagonal packing of fibrous structures or rods extremizes the energy of interaction between strands. If the strands are not straight, then it is still possible to form a perfect hexatic bundle. Conditions under which the perfect hexagonal packing of curved tubular structures may exist are formulated. Particular attention is given to closed or cycled arrangements of the rods like in the DNA toroids and spools. The closure or return constraints of the bundle result in an allowable group of automorphisms of the cross-sectional hexagonal lattice. The structure of this group is explored. Examples of open helical-like and closed toroidal-like bundles are presented. An expression for the elastic energy of a perfectly packed bundle of thin elastic rods is derived. The energy accounts for both the bending and torsional stiffnesses of the rods. It is shown that equilibria of the bundle correspond to solutions of a variational problem formulated for the curve representing the axis of the bundle. The functional involves a function of the squared curvature under the constraints on the total torsion and the length. The Euler-Lagrange equations are obtained in terms of curvature and torsion and due to the existence of the first integrals the problem is reduced to the quadrature. The three-dimensional shape of the bundle may be readily reconstructed by integration of the Ilyukhin-type equations in special cylindrical coordinates. The results are of universal nature and are applicable to various fibrous structures, in particular, to intramolecular liquid crystals formed by DNA condensed in toroids or packed inside the viral capsids. International Workshop on Biopolymers: Thermodynamics, Kinetics and Mechanics of DNA, RNA and Proteins, 30.05.2005-3.06.2005, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy.

  19. Bundle duct interaction studies for fuel assemblies. [LMFBR

    SciTech Connect

    Hsia, H.T.S.; Kaplan, S.

    1981-06-01

    It is known that the wire-wrapped rods and duct in an LMFBR are undergoing a gradual structural distortion from the initially uniform geometry under the combined effects of thermal expansion and irradiation induced swelling and creep. These deformations have a significant effect on flow characteristics, thus causing changes in thermal behavior such as cladding temperature and temperature distribution within a bundle. The temperature distribution may further enhance or retard irradiation induced deformation of the bundle. This report summarizes the results of the continuing effort in investigating the bundle-duct interaction, focusing on the need for the large development plant.

  20. Pressure Drop Characteristics in Tight-Lattice Bundles for Reduced-Moderation Water Reactors

    NASA Astrophysics Data System (ADS)

    Tamai, Hidesada; Kureta, Masatoshi; Yoshida, Hiroyuki; Akimoto, Hajime

    The reduced-moderation water reactor (RMWR) consists of several distinctive structures; a triangular tight-lattice configuration and a double-flat core. In order to design the RMWR core from the point of view of thermal-hydraulics, an evaluation method on pressure drop characteristics in the rod bundles at the tight-lattice configuration is required. In this study, calculated results by the Martinelli-Nelson's and Hancox's correlations were compared with experimental results in 4×5 rod bundles and seven-rod bundles. Consequently, the friction loss in two-phase flows becomes smaller at the tight-lattice configuration with the hydraulic diameter less than about 3mm. This reason is due to the difference of the configuration between the multi-rod bundle and the circular tube and due to the effect of the small hydraulic diameter on the two-phase multiplier.

  1. Gelation and mechanical response of patchy rods.

    PubMed

    Kazem, Navid; Majidi, Carmel; Maloney, Craig E

    2015-10-28

    We perform Brownian dynamics simulations to study the gelation of suspensions of attractive, rod-like particles. We show that in detail the rod-rod surface interactions can dramatically affect the dynamics of gelation and the structure and mechanics of the networks that form. If the attraction between the rods is perfectly smooth along their length, they will collapse into compact bundles. If the attraction is sufficiently corrugated or patchy, over time, a rigid space-spanning network will form. We study the structure and mechanical properties of the networks that form as a function of the fraction of the surface, f, that is allowed to bind. Surprisingly, the structural and mechanical properties are non-monotonic in f. At low f, there are not a sufficient number of cross-linking sites to form networks. At high f, rods bundle and form disconnected clusters. At intermediate f, robust networks form. The elastic modulus and yield stress are both non-monotonic in the surface coverage. The stiffest and strongest networks show an essentially homogeneous deformation under strain with rods re-orienting along the extensional axis. Weaker, more clumpy networks at high f re-orient relatively little with strong non-affine deformation. These results suggest design strategies for tailoring surface interactions between rods to yield rigid networks with optimal mechanical properties. PMID:26381995

  2. A Mechanistic Approach for the Prediction of Critical Power in BWR Fuel Bundles

    NASA Astrophysics Data System (ADS)

    Chandraker, Dinesh Kumar; Vijayan, Pallipattu Krishnan; Sinha, Ratan Kumar; Aritomi, Masanori

    The critical power corresponding to the Critical Heat Flux (CHF) or dryout condition is an important design parameter for the evaluation of safety margins in a nuclear fuel bundle. The empirical approaches for the prediction of CHF in a rod bundle are highly geometric specific and proprietary in nature. The critical power experiments are very expensive and technically challenging owing to the stringent simulation requirements for the rod bundle tests involving radial and axial power profiles. In view of this, the mechanistic approach has gained momentum in the thermal hydraulic community. The Liquid Film Dryout (LFD) in an annular flow is the mechanism of CHF under BWR conditions and the dryout modeling has been found to predict the CHF quite accurately for a tubular geometry. The successful extension of the mechanistic model of dryout to the rod bundle application is vital for the evaluation of critical power in the rod bundle. The present work proposes the uniform film flow approach around the rod by analyzing individual film of the subchannel bounded by rods with different heat fluxes resulting in different film flow rates around a rod and subsequently distributing the varying film flow rates of a rod to arrive at the uniform film flow rate as it has been found that the liquid film has a strong tendency to be uniform around the rod. The FIDOM-Rod code developed for the dryout prediction in BWR assemblies provides detailed solution of the multiple liquid films in a subchannel. The approach of uniform film flow rate around the rod simplifies the liquid film cross flow modeling and was found to provide dryout prediction with a good accuracy when compared with the experimental data of 16, 19 and 37 rod bundles under BWR conditions. The critical power has been predicted for a newly designed 54 rod bundle of the Advanced Heavy Water Reactor (AHWR). The selected constitutive models for the droplet entrainment and deposition rates validated for the dryout in tube were

  3. Heat transfer and fluid friction in bundles of twisted tubes

    NASA Astrophysics Data System (ADS)

    Dzyubenko, B. V.; Dreitser, G. A.

    1986-06-01

    The results of heat-transfer and friction studies in bundles of twisted tubes and rods with spiral wire-wrap spacers are analyzed, and recommendations are given for calculating the heat-transfer coefficient in heat exchangers using twisted tubes.

  4. Fiber bundle endocytoscopy

    PubMed Central

    Hughes, Michael; Chang, Tou Pin; Yang, Guang-Zhong

    2013-01-01

    Endocytoscopy is an optical biopsy technique which uses a miniaturized camera to capture white light microscopy images through an endoscope. We have developed an alternative design that instead relays images to an external camera via a coherent fiber bundle. In this paper we characterize the device and demonstrate microscopy of porcine tissue ex vivo. One advantage of our approach is the ease with which other bundle-compatible imaging modalities can be deployed simultaneously. We show this by acquiring quasi-simultaneous endocytoscopy and fluorescence confocal endomicroscopy images through a single fiber bundle. This opens up possibilities for multi-modal endomicroscopy, combining white light and fluorescence imaging. PMID:24409380

  5. MEGARA fiber bundles

    NASA Astrophysics Data System (ADS)

    Pérez-Calpena, A.; García-Vargas, María. Luisa; Arrillaga, X.; Gil de Paz, A.; Sánchez-Blanco, E.; Martínez-Delgado, I.; Carrera, M. A.; Gallego, J.; Carrasco, E.; Sánchez-Moreno, F. M.; Iglesias-Páramo, J.

    2014-07-01

    MEGARA (Multi Espectrógrafo en GTC de Alta Resolución para Astronomía) is the future optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) for the 10.4-m Gran Telescopio CANARIAS (GTC). MEGARA has three different fiber bundles, the Large Central Bundle covering 12.5 arcsec x 11.3 arcsec on sky, the Small Compact Bundle, of 8.5 arcsec x 6.7 arcsec, and a Fiber MOS positioner system that is able to place up to 100 mini-bundles with 7 fibers each in MOS configuration within a 3.5 arcmin x 3.5 arcmin FOV. The MEGARA focal plane subsystems are located at one of the GTC Folded Cassegrain focal stations. A field lens provides a telecentric focal plane, where the fibers are located. Micro-lenses arrays couple the telescope beam to the collimator focal ratio at the entrance of the fibers. Finally, the fibers, organized in bundles conducted the light from the focal plane to the pseudo-slit plates at the entrance of the MEGARA spectrograph, which shall be located at one of the Nasmyth platforms. This article also summarizes the prototypes already done and describes the set-up that shall be used to integrate fibers and micro-lens and characterize the fiber bundles.

  6. CONTROL ROD

    DOEpatents

    Zinn, W.H.; Ross, H.V.

    1958-11-18

    A control rod is described for a nuclear reactor. In certaln reactor designs it becomes desirable to use a control rod having great width but relatively llttle thickness. This patent is addressed to such a need. The neutron absorbing material is inserted in a triangular tube, leaving volds between the circular insert and the corners of the triangular tube. The material is positioned within the tube by the use of dummy spacers to achleve the desired absorption pattern, then the ends of the tubes are sealed with suitable plugs. The tubes may be welded or soldered together to form two flat surfaces of any desired width, and covered with sheetmetal to protect the tubes from damage. This design provides a control member that will not distort under the action of outside forces or be ruptured by gases generated within the jacketed control member.

  7. Bundle Binding in Polyelectrolyte Solutions

    SciTech Connect

    Stevens, M.J.

    1999-01-21

    Stiff polyelectrolytes are found to spontaneously form oriented bundles. Conditions under which bundling occurs are found. Molecular dynamics simulations show that divalent counterions are necessary, and the chains must be sufficiently long and stiff. No aggregation occurs for monovalent counterions. For flexible or short chains aggregation occurs, but bundle formation does not. Due to dynamical constraints the systems tend to order into a network of connected bundles, not a single bundle.

  8. Gelation And Mechanical Response of Patchy Rods

    NASA Astrophysics Data System (ADS)

    Kazem, Navid; Majidi, Carmel; Maloney, Craig

    We perform Brownian Dynamics simulations to study the gelation of suspensions of attractive, rod-like particles. We show that details of the particle-particle interactions can dramatically affect the dynamics of gelation and the structure and mechanics of the networks that form. If the attraction between the rods is perfectly smooth along their length, they will collapse into compact bundles. If the attraction is sufficiently corrugated or patchy, over time, a rigid space spanning network forms. We study the structure and mechanical properties of the networks that form as a function of the fraction of the surface that is allowed to bind. Surprisingly, the structural and mechanical properties are non-monotonic in the surface coverage. At low coverage, there are not a sufficient number of cross-linking sites to form networks. At high coverage, rods bundle and form disconnected clusters. At intermediate coverage, robust networks form. The elastic modulus and yield stress are both non-monotonic in the surface coverage. The stiffest and strongest networks show an essentially homogeneous deformation under strain with rods re-orienting along the extensional axis. Weaker, clumpy networks at high surface coverage exhibit relatively little re-orienting with strong non-affine deformation. These results suggest design strategies for tailoring surface interactions between rods to yield rigid networks with optimal properties. National Science Foundation and the Air Force Office of Scientific Research.

  9. Dynamics of flagellar bundling

    NASA Astrophysics Data System (ADS)

    Janssen, Pieter; Graham, Michael

    2010-11-01

    Flagella are long thin appendages of microscopic organisms used for propulsion in low-Reynolds environments. For E. coli the flagella are driven by a molecular motor, which rotates the flagella in a counter-clockwise motion (CCM). When in a forward swimming motion, all flagella bundle up. If a motor reverses rotation direction, the flagella unbundle and the cell makes a tumbling motion. When all motors turn in the same CC direction again, the flagella bundle up, and forward swimming continues. To investigate the bundling, we consider two flexible helices next to each other, as well as several flagella attached to a spherical body. Each helix is modeled as several prolate spheroids connected at the tips by springs. For hydrodynamic interactions, we consider the flagella to made up of point forces, while the finite size of the body is incorporated via Fax'en's laws. We show that synchronization occurs quickly relative to the bundling process. For flagella next to each other, the initial deflection is generated by rotlet interactions generated by the rotating helices. At longer times, simulations show the flagella only wrap once around each other, but only for flagella that are closer than about 4 helix radii. Finally, we show a run-and-tumble motion of the body with attached flagella.

  10. Experimental study of burnout in channels with twisted fuel rods

    NASA Astrophysics Data System (ADS)

    Bol'Shakov, V. V.; Bashkirtsev, S. M.; Kobzar', L. L.; Morozov, A. G.

    2007-05-01

    The results of experimental studies of pressure drop and critical heat flux in the models of fuel assemblies (FAs) with fuel rod simulators twisted relative to the longitudinal axis and a three-ray cross section are considered. The experimental data are compared to the results obtained with the use of techniques adopted for design calculations with fuel rod bundles of type-VVER reactors.

  11. The design of the DUPIC spent fuel bundle counter

    SciTech Connect

    Menlove, H.O.; Rinard, P.M.; Kroncke, K.E.; Lee, Y.G.

    1997-05-01

    A neutron coincidence detector had been designed to measure the amount of curium in the fuel bundles and associated process samples used in the direct use of plutonium in Canadian deuterium-uranium (CANDU) fuel cycle. All of the sample categories are highly radioactive from the fission products contained in the pressurized water reactor (PWR) spent fuel feed stock. Substantial shielding is required to protect the He-3 detectors from the intense gamma rays. The Monte Carlo neutron and photon calculational code has been used to design the counter with a uniform response profile along the length of the CANDU-type fuel bundle. Other samples, including cut PWR rods, process powder, waste, and finished rods, can be measured in the system. This report describes the performance characteristics of the counter and support electronics. 3 refs., 23 figs., 6 tabs.

  12. Annular Flow Liquid Film Dynamics in Pipes and Bod Bundle

    NASA Astrophysics Data System (ADS)

    Ju, Peng

    improvement on the prediction accuracy compared to other models. In order to develop detailed model of the annular two-phase flow, the average liquid film thickness in rod bundle is an important parameter. It can significantly affect the occurrence of dryout and post-dryout phenomena on heater surfaces. Most research on film thickness has been focused on pipe flows. Data in rod bundle geometry are very limited. However data in rod bundle geometry is much more valuable for reactor safety modeling and calculations. Because of this, an experiment to measure liquid film thickness has been performed for the air-water annular flow in an 8x8 BWR rod bundle. Film thickness data were obtained both on the rods and on the channel wall. Data were recorded at four axial locations within the rod bundle. This included locations just before and just after a spacer grid. This allows the spacer grids effect on the film thickness to be evaluated. The minimum film thickness was measured at the center rod. Also, the presence of the spacer grid results in reduced film thickness. Finally, the models for film thickness and interfacial friction factor in pipes have been implemented into rod bundle geometry with some approaches. These approaches are mainly focused on the length scale and flow conditions. With these methods, the correlations can be successfully used for rod bundle geometry.

  13. Laboratory manual for salt-mixing test in 37- and 217-pin bundles. [LMFBR

    SciTech Connect

    Chan, Y.N.; Todreas, N.E.

    1980-08-01

    This laboratory manual deals with the procedure employed during salt tracer experiments used in evaluating the hydraulic characteristics of a rod bundle. A description of the standard equipment used is given together with the details of manufacture of probes used for detecting the salt concentration. Details of the bundle construction have been excluded as they are availble in the reference cited. An attempt has been made to point out potential trouble areas and procedures.

  14. Bundled monocapillary optics

    DOEpatents

    Hirsch, Gregory

    2002-01-01

    A plurality of glass or metal wires are precisely etched to form the desired shape of the individual channels of the final polycapillary optic. This shape is created by carefully controlling the withdrawal speed of a group of wires from an etchant bath. The etched wires undergo a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation being used. This reflective surface may be a single layer of material, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The collection of individual wires is assembled into a close-packed multi-wire bundle, and the wires are bonded together in a manner which preserves the close-pack configuration, irrespective of the local wire diameter. The initial wires are then removed by either a chemical etching procedure or mechanical force. In the case of chemical etching, the bundle is generally segmented by cutting a series of etching slots. Prior to removing the wire, the capillary array is typically bonded to a support substrate. The result of the process is a bundle of precisely oriented radiation-reflecting hollow channels. The capillary optic is used for efficiently collecting and redirecting the radiation from a source of radiation which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, a synchrotron radiation source, a reactor or spallation source of neutrons, or some other source.

  15. Material distribution in light water reactor-type bundles tested under severe accident conditions

    SciTech Connect

    Noack, V.; Hagen, S.J.L.; Hofmann, P.; Schanz, G.; Sepold, L.K.

    1997-02-01

    Severe fuel damage experiments simulating small-break loss-of-coolant accidents have been carried out in the CORA out-of-pile test facility at Forschungszentrum Karlsruhe. Rod bundles with electrically heated fuel rod simulators containing annular UO{sub 2} pellets, UO{sub 2} full pellet rods, and absorber rods of two kinds (Ag/In/Cd to represent pressurized water reactor conditions and B{sub 4}C to represent boiling water reactor and VVER-1000 fuel elements) were subjected to temperature transients up to 2,300 K. A special method was applied to determine the axial mass distribution of bundle materials. The low-temperature melt formation by various interactions between zirconium and components of absorber and spacer grids strongly influences the bundle degradation and material relocation. Absorber materials can separate from the fuel by a noncoherent relocation of the materials at different temperatures. The distributions of solidified materials in the different test bundles show a clear dependence on the axial temperature profile. Coolant channel blockages are observed mainly at the lower end of the bundle, i.e., near the lowest elevation at which an oxidation excursion resulting from the highly exothermic zirconium-steam reaction had been experienced. This elevation corresponds with a steep axial temperature gradient in the maximum temperature attained. Oxide layers on Zircaloy result in reduced melt formation.

  16. Countercurrent flow-limiting characteristics of a Savannah River Plant control rod septifoil

    SciTech Connect

    Anderson, J.L.

    1992-07-01

    Experiments were performed at the Idaho National Engineering Laboratory to investigate the counter-current flow limiting characteristics of a Savannah River Plant control rod septifoil assembly. These experiments were unheated, using air and water as the working fluids. Results are presented in terms of the Wallis flooding correlation for several different control rod configurations. Flooding was observed to occur in the vicinity of the inlet slots/holes of the septifoil, rather than within the rod bundle at the location of the minimum flow area. Nearly identical flooding characteristics of the septifoil were observed for configurations with zero, three, and four rods inserted, but significantly different results occurred with 5 rods inserted.

  17. Rod examination gauge

    SciTech Connect

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  18. Growth of Bi2O3 rods using a trimethylbismuth and oxygen mixture

    NASA Astrophysics Data System (ADS)

    Kim, H. W.; Myung, J. H.; Shim, S. H.; Lee, C.

    2006-07-01

    We have successfully grown the rod-like structures of bismuth oxide (Bi2O3) on silicon substrate by a reaction of a trimethylbismuth (TMBi) and oxygen (O2) mixture without using any catalyst. We have characterized the samples by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The products consisted of bundles of rod-like structures. The Bi2O3 rods were of monoclinic structure.

  19. FUEL ROD ASSEMBLY

    DOEpatents

    Hutter, E.

    1959-09-01

    A cluster of nuclear fuel rods aod a tubular casing through which a coolant flows in heat-change contact with the ruel rods are described. The casting is of trefoil section and carries the fuel rods, each of which has two fin engaging the serrated fins of the other two fuel rods, whereby the fuel rods are held in the casing and are interlocked against relative longitudinal movement.

  20. ADF/cofilin-actin rods in neurodegenerative diseases

    PubMed Central

    Bamburg, J.R.; Bernstein, B.W.; Davis, R.C.; Flynn, K.C.; Goldsbury, C.; Jensen, J.R.; Maloney, M.T.; Marsden, I.T.; Minamide, L.S.; Pak, C.W.; Shaw, A.E.; Whiteman, I.; Wiggan, O.

    2015-01-01

    Dephosphorylation (activation) of cofilin, an actin binding protein, is stimulated by initiators of neuronal dysfunction and degeneration including oxidative stress, excitotoxic glutamate, ischemia, and soluble forms of β-amyloid peptide (Aβ). Hyperactive cofilin forms rod-shaped cofilin-saturated actin filament bundles (rods). Other proteins are recruited to rods but are not necessary for rod formation. Neuronal cytoplasmic rods accumulate within neurites where they disrupt synaptic function and are a likely cause of synaptic loss without neuronal loss, as occurs early in dementias. Different rod-inducing stimuli target distinct neuronal populations within the hippocampus. Rods form rapidly, often in tandem arrays, in response to stress. They accumulate phosphorylated tau that immunostains for epitopes present in “striated neuropil threads,” characteristic of tau pathology in Alzheimer disease (AD) brain. Thus, rods might aid in further tau modifications or assembly into paired helical filaments, the major component of neurofibrillary tangles (NFTs). Rods can occlude neurites and block vesicle transport. Some rod-inducing treatments cause an increase in secreted Aβ. Thus rods may mediate the loss of synapses, production of excess Aβ, and formation of NFTs, all of the pathological hallmarks of AD. Cofilin-actin rods also form within the nucleus of heat-shocked neurons and are cleared from cells expressing wild type huntingtin protein but not in cells expressing mutant or silenced huntingtin, suggesting a role for nuclear rods in Huntington disease (HD). As an early event in the neurodegenerative cascade, rod formation is an ideal target for therapeutic intervention that might be useful in treatment of many different neurological diseases. PMID:20088812

  1. [Masquerading bundle branch block].

    PubMed

    Kukla, Piotr; Baranchuk, Adrian; Jastrzębski, Marek; Bryniarski, Leszek

    2014-01-01

    We here describe a surface 12-lead electrocardiogram (ECG) of a 72-year-old female with a prior history of breast cancer and chemotherapy-induced cardiomyopathy. An echocardiogram revealed left ventricular dysfunction, ejection fraction of 23%, with mild enlarged left ventricle. The 12-lead ECG showed atrial fibrillation with a mean heart rate of about 100 bpm, QRS duration 160 ms, QT interval 400 ms, right bundle branch block (RBBB) and left anterior fascicular block (LAFB). The combination of RBBB features in the precordial leads and LAFB features in the limb leads is known as ''masquerading bundle branch block''. In most cases of RBBB and LAFB, the QRS axis deviation is located between - 80 to -120 degrees. Rarely, when predominant left ventricular forces are present, the QRS axis deviation is near about -90 degrees, turning the pattern into an atypical form. In a situation of RBBB associated with LAFB, the S wave can be absent or very small in lead I. Such a situation is the result of not only purely LAFB but also with left ventricular hypertrophy and/or focal block due to scar (extensive anterior myocardial infarction) or fibrosis (cardiomyopathy). Sometimes, this specific ECG pattern is mistaken for LBBB. RBBB with LAFB may imitate LBBB either in the limb leads (known as 'standard masquerading' - absence of S wave in lead I), or in the precordial leads (called 'precordial masquerading' - absence of S wave in leads V₅ and V₆). Our ECG showed both these types of masquerading bundle branch block - absence of S wave in lead I and in leads V₅ and V₆. PMID:24469750

  2. Bundle Security Protocol for ION

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.; Birrane, Edward J.; Krupiarz, Christopher

    2011-01-01

    This software implements bundle authentication, conforming to the Delay-Tolerant Networking (DTN) Internet Draft on Bundle Security Protocol (BSP), for the Interplanetary Overlay Network (ION) implementation of DTN. This is the only implementation of BSP that is integrated with ION.

  3. Monad constructions of omalous bundles

    NASA Astrophysics Data System (ADS)

    Henni, Abdelmoubine Amar; Jardim, Marcos

    2013-12-01

    We consider a particular class of holomorphic vector bundles relevant for supersymmetric string theory, called omalous, over nonsingular projective varieties. We use monads to construct examples of such bundles over 3-fold hypersurfaces in P4, complete intersection Calabi-Yau manifolds in Pk, blow-ups of P2 at n distinct points, and products Pm×Pn.

  4. Control rod drive

    SciTech Connect

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  5. Fiber bundle phase conjugate mirror

    SciTech Connect

    Ward, Benjamin G.

    2012-05-01

    An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

  6. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1998-01-01

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

  7. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1998-01-01

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

  8. Cable Bundle Wire Derating

    NASA Technical Reports Server (NTRS)

    Lundquist, Ray A.; Leidecker, Henning

    1999-01-01

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

  9. Piston rod seal

    DOEpatents

    Lindskoug, Stefan

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  10. Effect of interfacial roughness parameters on the fiber pushout behavior of a model composite

    SciTech Connect

    Parthasarathy, T.A. ); Barlage, D.R. . Dept. of Engineering); Jero, P.D.; Kerans, R.J. )

    1994-12-01

    The effect of interfacial roughness on the frictional sliding in composites has been studied using fiber pushout and pushback tests on a model composite of Plexiglas rods in an epoxy matrix. Different extents of roughness were introduced on the Plexiglas rods and the resulting roughness profiles measured. The roughness profiles were characterized using six different roughness parameters. An attempt was made to find a correlation between the sliding resistance and the selected roughness parameters. A parameter defined as the maximum coefficient in the Fourier transform of the roughness profile was found to yield the best correlation. If the roughness introduced is periodic, then the pushout traces exhibit periodic dips, but the magnitude of this periodic dip is significantly smaller than the seating drop obtained from pushback tests.

  11. Transition from a Linear to a Harmonic Potential in Collective Dynamics of a Multifilament Actin Bundle.

    PubMed

    Schnauß, Jörg; Golde, Tom; Schuldt, Carsten; Schmidt, B U Sebastian; Glaser, Martin; Strehle, Dan; Händler, Tina; Heussinger, Claus; Käs, Josef A

    2016-03-11

    Attractive depletion forces between rodlike particles in highly crowded environments have been shown through recent modeling and experimental approaches to induce different structural and dynamic signatures depending on relative orientation between rods. For example, it has been demonstrated that the axial attraction between two parallel rods yields a linear energy potential corresponding to a constant contractile force of 0.1 pN. Here, we extend pairwise, depletion-induced interactions to a multifilament level with actin bundles, and find contractile forces up to 3 pN. Forces generated due to bundle relaxation were not constant, but displayed a harmonic potential and decayed exponentially with a mean decay time of 3.4 s. Through an analytical model, we explain these different fundamental dynamics as an emergent, collective phenomenon stemming from the additive, pairwise interactions of filaments within a bundle. PMID:27015510

  12. Transition from a Linear to a Harmonic Potential in Collective Dynamics of a Multifilament Actin Bundle

    NASA Astrophysics Data System (ADS)

    Schnauß, Jörg; Golde, Tom; Schuldt, Carsten; Schmidt, B. U. Sebastian; Glaser, Martin; Strehle, Dan; Händler, Tina; Heussinger, Claus; Käs, Josef A.

    2016-03-01

    Attractive depletion forces between rodlike particles in highly crowded environments have been shown through recent modeling and experimental approaches to induce different structural and dynamic signatures depending on relative orientation between rods. For example, it has been demonstrated that the axial attraction between two parallel rods yields a linear energy potential corresponding to a constant contractile force of 0.1 pN. Here, we extend pairwise, depletion-induced interactions to a multifilament level with actin bundles, and find contractile forces up to 3 pN. Forces generated due to bundle relaxation were not constant, but displayed a harmonic potential and decayed exponentially with a mean decay time of 3.4 s. Through an analytical model, we explain these different fundamental dynamics as an emergent, collective phenomenon stemming from the additive, pairwise interactions of filaments within a bundle.

  13. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  14. CRUCIFORM CONTROL ROD JOINT

    DOEpatents

    Thorp, A.G. II

    1962-08-01

    An invention is described which relates to nuclear reactor control rod components and more particularly to a joint between cruciform control rod members and cruciform control rod follower members. In one embodiment this invention provides interfitting crossed arms at adjacent ends of a control rod and its follower in abutting relation. This holds the members against relative opposite longitudinal movement while a compression member keys the arms against relative opposite rotation around a common axis. Means are also provided for centering the control rod and its follower on a common axis and for selectively releasing the control rod from its follower for the insertion of a replacement of the control rod and reuse of the follower. (AEC)

  15. Evaluating big deal journal bundles

    PubMed Central

    Bergstrom, Theodore C.; Courant, Paul N.; McAfee, R. Preston; Williams, Michael A.

    2014-01-01

    Large commercial publishers sell bundled online subscriptions to their entire list of academic journals at prices significantly lower than the sum of their á la carte prices. Bundle prices differ drastically between institutions, but they are not publicly posted. The data that we have collected enable us to compare the bundle prices charged by commercial publishers with those of nonprofit societies and to examine the types of price discrimination practiced by commercial and nonprofit journal publishers. This information is of interest to economists who study monopolist pricing, librarians interested in making efficient use of library budgets, and scholars who are interested in the availability of the work that they publish. PMID:24979785

  16. Evaluating big deal journal bundles.

    PubMed

    Bergstrom, Theodore C; Courant, Paul N; McAfee, R Preston; Williams, Michael A

    2014-07-01

    Large commercial publishers sell bundled online subscriptions to their entire list of academic journals at prices significantly lower than the sum of their á la carte prices. Bundle prices differ drastically between institutions, but they are not publicly posted. The data that we have collected enable us to compare the bundle prices charged by commercial publishers with those of nonprofit societies and to examine the types of price discrimination practiced by commercial and nonprofit journal publishers. This information is of interest to economists who study monopolist pricing, librarians interested in making efficient use of library budgets, and scholars who are interested in the availability of the work that they publish. PMID:24979785

  17. Tube bundle system

    PubMed Central

    Marchewka, W.; Mohamed, K.; Addis, J.; Karnack, F.

    2015-01-01

    A tube bundle system (TBS) is a mechanical system for continuously drawing gas samples through tubes from multiple monitoring points located in an underground coal mine. The gas samples are drawn via vacuum pump to the surface and are typically analyzed for oxygen, methane, carbon dioxide and carbon monoxide. Results of the gas analyses are displayed and recorded for further analysis. Trends in the composition of the mine atmosphere, such as increasing methane or carbon monoxide concentration, can be detected early, permitting rapid intervention that prevents problems, such as a potentially explosive atmosphere behind seals, fire or spontaneous combustion. TBS is a well-developed technology and has been used in coal mines around the world for more than 50 years. Most longwall coal mines in Australia deploy a TBS, usually with 30 to 40 monitoring points as part of their atmospheric monitoring. The primary uses of a TBS are detecting spontaneous combustion and maintaining sealed areas inert. The TBS might also provide mine atmosphere gas composition data after a catastrophe occurs in an underground mine, if the sampling tubes are not damaged. TBSs are not an alternative to statutory gas and ventilation airflow monitoring by electronic sensors or people; rather, they are an option to consider in an overall mine atmosphere monitoring strategy. This paper describes the hardware, software and operation of a TBS and presents one example of typical data from a longwall coal mine PMID:26306052

  18. BWR fuel rod performance evaluation program. Final report

    SciTech Connect

    Rowland, T.C.

    1986-05-01

    The joint EPRI/GE fuel performance program, RP510-1, involved thorough preirradiation characterization of fuel used in lead test assemblies, detailed surveillance of their operation, and interim site examinations of the assemblies during reactor outages. The program originally included four GE-5 lead test assemblies operating in the Peach Bottom-2 reactor. The program was later modified to include the pressurized fuel rod test assembly in the Peach Bottom-3 reactor (RP510-2). The program modification also included extending the operation of the Peach Bottom-2 and Peach Bottom-3 lead test assembly fuel beyond normal discharge exposures. Interim site examination results following the first four cycles of operation of the Peach Bottom-2 lead test assemblies up to 35 GWd/MT and the examination of the Peach Bottom-3 pressurized test assembly at 32 GWd/MT are presented in this report. Elements of the examinations included visual examination of the fuel bundles; individual fuel rod visual examinations, rod length measurements, ultrasonic and eddy current nondestructive testing, Zircaloy cladding oxide thickness measurements and fission gas measurements. Channel measurements were made on the PB-2 Lead Test Assemblies after each of the first three operating cycles. All of the bundles were found to be in good condition. Since the pressurized test assembly contained pressurized and nonpressurized fuel rods in symmetric positions, it was possible to make direct comparisons of the fission gas release from pairs of pressurized and nonpressurized fuel rods with identical power histories. With one exception, the release was less from the pressurized fuel rod of each pair. Fuel rod power histories were calculated using new physics methods for all of the fuel rods that were punctured for fission gas release measurements. 28 refs., 41 figs., 16 tabs.

  19. Reconnection of superfluid vortex bundles.

    PubMed

    Alamri, Sultan Z; Youd, Anthony J; Barenghi, Carlo F

    2008-11-21

    Using the vortex filament model and the Gross-Pitaevskii nonlinear Schroedinger equation, we show that bundles of quantized vortex lines in He II are structurally robust and can reconnect with each other maintaining their identity. We discuss vortex stretching in superfluid turbulence and show that, during the bundle reconnection process, kelvin waves of large amplitude are generated, in agreement with the finding that helicity is produced by nearly singular vortex interactions in classical Euler flows. PMID:19113421

  20. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  1. Pull rod assembly

    DOEpatents

    Cioletti, O.C.

    1988-04-21

    A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  2. Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

    DOE PAGESBeta

    Christon, Mark A.; Lu, Roger; Bakosi, Jozsef; Nadiga, Balasubramanya T.; Karoutas, Zeses; Berndt, Markus

    2016-06-29

    Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuelmore » rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid–structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Furthermore, robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.« less

  3. FUEL ROD CLUSTERS

    DOEpatents

    Schultz, A.B.

    1959-08-01

    A cluster of nuclear fuel rods and a tubular casing therefor through which a coolant flows in heat-exchange contact with the fuel rods is described. The fuel rcds are held in the casing by virtue of the compressive force exerted between longitudinal ribs of the fuel rcds and internal ribs of the casing or the internal surfaces thereof.

  4. Roughness and function

    NASA Astrophysics Data System (ADS)

    Thomas, T. R.

    2014-01-01

    A function map is used to locate applications of roughness in separation-velocity space. The importance of roughness in contact mechanics is demonstrated and versions of the plasticity index are introduced and compared. Case studies of roughness and function are presented from tribology and the life sciences. Tribological examples are taken from the automotive industry and include the manufacture of vehicle bodies, and drive train tribology, particularly cylinder liner, cam and gearbox friction and wear. From the life sciences, problems of prosthetic fixation and tribology are shown to depend on roughness. The interaction of haptics and surface finish is described and illustrated. A number of other areas of application are listed. Finally the likely future importance of structured surfaces is discussed.

  5. Bundle Formation in Biomimetic Hydrogels.

    PubMed

    Jaspers, Maarten; Pape, A C H; Voets, Ilja K; Rowan, Alan E; Portale, Giuseppe; Kouwer, Paul H J

    2016-08-01

    Bundling of single polymer chains is a crucial process in the formation of biopolymer network gels that make up the extracellular matrix and the cytoskeleton. This bundled architecture leads to gels with distinctive properties, including a large-pore-size gel formation at very low concentrations and mechanical responsiveness through nonlinear mechanics, properties that are rarely observed in synthetic hydrogels. Using small-angle X-ray scattering (SAXS), we study the bundle formation and hydrogelation process of polyisocyanide gels, a synthetic material that uniquely mimics the structure and mechanics of biogels. We show how the structure of the material changes at the (thermally induced) gelation point and how factors such as concentration and polymer length determine the architecture, and with that, the mechanical properties. The correlation of the gel mechanics and the structural parameters obtained from SAXS experiments is essential in the design of future (synthetic) mimics of biopolymer networks. PMID:27409975

  6. Cohomology of line bundles: Applications

    NASA Astrophysics Data System (ADS)

    Blumenhagen, Ralph; Jurke, Benjamin; Rahn, Thorsten; Roschy, Helmut

    2012-01-01

    Massless modes of both heterotic and Type II string compactifications on compact manifolds are determined by vector bundle valued cohomology classes. Various applications of our recent algorithm for the computation of line bundle valued cohomology classes over toric varieties are presented. For the heterotic string, the prime examples are so-called monad constructions on Calabi-Yau manifolds. In the context of Type II orientifolds, one often needs to compute cohomology for line bundles on finite group action coset spaces, necessitating us to generalize our algorithm to this case. Moreover, we exemplify that the different terms in Batyrev's formula and its generalizations can be given a one-to-one cohomological interpretation. Furthermore, we derive a combinatorial closed form expression for two Hodge numbers of a codimension two Calabi-Yau fourfold.

  7. Evaluation of nonequilibrium effects in bundle dispersed-flow film boiling. [PWR; BWR

    SciTech Connect

    Morris, D.G.; Mullins, C.B.; Yoder, G.L.

    1983-01-01

    The effects of thermodynamic nonequilibrium in dispersed flow film boiling heat transfer are examined. Steady-state and transient rod-bundle data are used to evaluate several empirical heat-transfer models commonly employed to predict post-CHF behavior. The models that account for thermodynamic nonequilibrium perform adequately, while those that ignore nonequilibrium effects incur errors in wall superheat as high as 190/sup 0/K. Nonequilibrium effects can also be treated by explicitly modeling the phenomena. The thermal-hydraulic code COBRA-TF employs this approach. Using bundle data, the models in the code are evaluated. Analysis suggests that the interfacial heat transfer is overpredicted.

  8. Rod Photoreceptors Detect Rapid Flicker

    ERIC Educational Resources Information Center

    Conner, J. D.; MacLeod, Donald I. A.

    1977-01-01

    Rod-isolation techniques show that light-adapted human rods detect flicker frequencies as high as 28 hertz, and that the function relating rod critical flicker frequency to stimulus intensity contains two distinct branches. (MLH)

  9. Chirality and equilibrium biopolymer bundles.

    PubMed

    Grason, Gregory M; Bruinsma, Robijn F

    2007-08-31

    We use continuum theory to show that chirality is a key thermodynamic control parameter for the aggregation of biopolymers: chirality produces a stable disperse phase of hexagonal bundles under moderately poor solvent conditions, as has been observed in in vitro studies of F actin [O. Pelletier et al., Phys. Rev. Lett. 91, 148102 (2003)]. The large characteristic radius of these chiral bundles is not determined by a mysterious long-range molecular interaction but by in-plane shear elastic stresses generated by the interplay between a chiral torque and an unusual, but universal, nonlinear gauge term in the strain tensor of ordered chains that is imposed by rotational invariance. PMID:17931038

  10. Extensional bundle waveguide techniques for measuring flow of hot fluids.

    PubMed

    Lynnworth, Lawrence C; Liu, Yi; Umina, John A

    2005-04-01

    A bundle of acoustically slender metal rods, each thin compared to wavelength, tightly packed within a sheath, and welded closed at each end, provides a dispersion-free waveguide assembly that acts as a thermal buffer between a transducer and the hot fluid medium the flow of which is to be measured. Gas and steam flow applications have ranged up to 600 degrees C. Liquid applications have ranged from cryogenic (-160 degrees C) to 500 degrees C and include intermittent two-phase flows. The individual rods comprising the bundle usually are approximately one millimeter in diameter. The sheath, made of a pipe or tube, typically has an outside diameter of 12.7 to about 33 mm and usually is about 300 mm long. Materials for the sheath and bundle are selected to satisfy requirements of compatibility with the fluid as well as for acoustic properties. Corrosion-resistant alloys such as 316SS and titanium are commonly used. The buffers are used with transducers that are metal-encapsulated and certified for use in hazardous areas. They operate at a frequency in the range of 0.1 to 1 MHz. The radiating end of the buffer is usually flat and perpendicular to the buffer's main axis. In some cases the end of the buffer is stepped or angled. Angling the radiating faces at approximately 2 degrees to overcome beam drift at Mach 0.1 recently contributed to solving a high-temperature high-velocity flow measurement problem. The temperature in this situation was 300 degrees C, and the gas molecular weight was about 95, with pressure 0.9 to 1.1 bar. PMID:16060500

  11. Fault Roughness Records Strength

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Candela, T.; Kirkpatrick, J. D.

    2014-12-01

    Fault roughness is commonly ~0.1-1% at the outcrop exposure scale. More mature faults are smoother than less mature ones, but the overall range of roughness is surprisingly limited which suggests dynamic control. In addition, the power spectra of many exposed fault surfaces follow a single power law over scales from millimeters to 10's of meters. This is another surprising observation as distinct structures such as slickenlines and mullions are clearly visible on the same surfaces at well-defined scales. We can reconcile both observations by suggesting that the roughness of fault surfaces is controlled by the maximum strain that can be supported elastically in the wallrock. If the fault surface topography requires more than 0.1-1% strain, it fails. Invoking wallrock strength explains two additional observations on the Corona Heights fault for which we have extensive roughness data. Firstly, the surface is isotropic below a scale of 30 microns and has grooves at larger scales. Samples from at least three other faults (Dixie Valley, Mount St. Helens and San Andreas) also are isotropic at scales below 10's of microns. If grooves can only persist when the walls of the grooves have a sufficiently low slope to maintain the shape, this scale of isotropy can be predicted based on the measured slip perpendicular roughness data. The observed 30 micron scale at Corona Heights is consistent with an elastic strain of 0.01 estimated from the observed slip perpendicular roughness with a Hurst exponent of 0.8. The second observation at Corona Heights is that slickenlines are not deflected around meter-scale mullions. Yielding of these mullions at centimeter to meter scale is predicted from the slip parallel roughness as measured here. The success of the strain criterion for Corona Heights supports it as the appropriate control on fault roughness. Micromechanically, the criterion implies that failure of the fault surface is a continual process during slip. Macroscopically, the

  12. Exploring Bundling Theory with Geometry

    ERIC Educational Resources Information Center

    Eckalbar, John C.

    2006-01-01

    The author shows how instructors might successfully introduce students in principles and intermediate microeconomic theory classes to the topic of bundling (i.e., the selling of two or more goods as a package, rather than separately). It is surprising how much students can learn using only the tools of high school geometry. To be specific, one can…

  13. PDS4 Bundle Creation Governance Using BPMN

    NASA Astrophysics Data System (ADS)

    Radulescu, C.; Levoe, S. R.; Algermissen, S. S.; Rye, E. D.; Hardman, S. H.

    2015-06-01

    The AMMOS-PDS Pipeline Service (APPS) provides a Bundle Builder tool, which governs the process of creating, and ultimately generates, PDS4 bundles incrementally, as science products are being generated.

  14. Control rod driveline and grapple

    DOEpatents

    Germer, John H.

    1987-01-01

    A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

  15. Global analysis of bundle behavior in pressurized water reactor specific CORA experiments

    SciTech Connect

    Hering, W. ); Minato, Kazuo; Nagase, Fumihisa )

    1993-04-01

    At Kernforschungszentrum Karlsruhe, out-of-pile bundle experiments are performed in the CORA facility to investigate the behavior of light water reactor fuel elements during severe fuel damage accidents. To analyze the phenomena observed during the tests, such as claddin failure, oxidation, and deformation, as well as their influence on the post test bundle state, four pressurized water reactor specific tests are selected: CORA-2, CORA-3, CORA-5, and CORA-12. From each of these tests, a detailed global analysis using all the measured temperatures, pressures, and fluid compositions as well as videoscope information has been performed. To describe the post test bundle state quantitatively, axial profiles of the bundle cross-section area, the damage state of the rods, the average cladding oxidation, and the damage to the pellets are measured. The effects of CORA-specific components on the bundle melt progression and the measured axial profiles are identified and assessed. Most of the observations during the tests as well as the post test bundle state can be explained by the established common sequence of phenomena. For a better understanding of the melt progression, some physical phenomena, such as the energy release associated with the double-sided oxidation of the cladding, the melt release, or the melt relocation, must be analyzed in detail.

  16. Mesoscale roughness of Venus

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.; Frawley, James J.

    1994-01-01

    The global distribution of multi-kilometer (approx. 9 km) length scale 'roughness' (hereafter mesoscale roughness or MR) on Venus can be estimated from the Magellan global altimetry dataset (GxDR) and then compared with MR data derived for Earth from 5' ETOP5 data and for Mars (from USGS Mars DTM dataset). The mesoscale roughness parameter (MR) represents the RMS variance in meters of the actual planetary surface topography relative to the best fitting tangent plane defined on the basis of a 3x3 pixel sliding window. The best-fit plane was computed using a least-squares solution which minimizes delta H, the sum of the squares of the differences between the 9 local elevation values (H(sub i)), and the elevation of best-fit plane at the same grid location. Using the best-fit plane and delta H, we have computed the RMS 'roughness' var(delta R), where this parameter is always minimized on the basis of its calculation using least squares. We have called this 'ruggedness' parameter the Mesoscale Roughness (MR) because it is directly related to the high-frequency variance of topography after mesoscale slopes and tilts (i.e., for Venus, the baseline over which MR is computed (dx) is approx. 8.8 km and dx for Earth is approx. 9.3 km) are removed. As such, MR represents the degree to which a planetary surface is more rugged than approximately 10 km scale facets or tilts. It should not be confused with the radar 'RMS Roughness' parameter computed at 0.1 to 10 m length scales on the basis of the Magellan radar altimeter echo. We will use our MR parameter to investigate the global ruggedness properties of Venus as they relate to geological provinces and in comparison with the spatial pattern of MR for Earth and Mars.

  17. On the Vortex Sound from Rotating Rods

    NASA Technical Reports Server (NTRS)

    Yudin, E. Y.

    1947-01-01

    The motion of different bodies imersed in liquid or gaseous media is accompanied by characteristic sound which is excited by the formation of unstable surfaces of separation behind the body, usually disintegrating into a system of discrete vortices(such as the Karman vortex street due to the flow about an infintely long rod, etc.).In the noise from fans,pumps,and similar machtnery, vortexnQif3eI?Yequently predominates. The purpose of this work is to elucidate certain questions of the dependence ofthis sound upon the aerodynamic parameters and the tip speed of the rotating rods,or blades. Although scme material is given below,insufficientto calculate the first rough approximation to the solution of this question,such as the mechanics of vortex formation,never the less certain conclusions maybe found of practical application for the reduction of noise from rotating blades.

  18. Fluid Dynamics in Sucker Rod Pumps

    SciTech Connect

    Cutler, R.P.; Mansure, A.J.

    1999-01-14

    Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been fully investigated. A project was conducted at Sandia National Laboratories to develop unimproved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verify and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.

  19. Turbulence analysis of rough wall channel flows based on direct numerical simulation

    SciTech Connect

    Mishra, A. V.; Bolotnov, I. A.

    2012-07-01

    Direct numerical simulation (DNS) of rough wall channel flows was performed for various surface roughnesses. The goal of the presented research is to investigate the effect of nucleating bubbles in subcooled boiling conditions on the turbulence. The nucleating bubbles are represented by hemispherical roughness elements at the wall. The stabilized finite element based code, PHASTA, is used to perform the simulations. Validation against theoretical, experimental and numerical data is performed for smooth channel flow and rectangular rod type of roughness. The presence of roughness elements affects the flow structure within the roughness sublayer, which is estimated to be 5 times the height of roughness elements. DNS observations are consistent with this result and demonstrate the flow homogeneity above 50 viscous units. The influence of roughness elements layout and density on the turbulence parameters is also demonstrated and analyzed. (authors)

  20. Salt-Induced Electrospun Patterned Bundled Fibers for Spatially Regulating Cellular Responses.

    PubMed

    Cho, Mira; Kim, Seung-Hyun; Jin, Gyuhyung; Park, Kook In; Jang, Jae-Hyung

    2016-06-01

    Implementing patterned fibrous matrices can offer a highly valuable platform for spatially orchestrating hierarchical cellular constructs, specifically for neural engineering approaches, in which striated alignment or directional growth of axons are key elements for the functional recovery of damaged nervous systems. Thus, understanding the structural parameters of patterned fibrous matrices that can effectively promote neural growth can provide crucial clues for designing state-of-the-art tissue engineering scaffolds. To this end, salt-induced electrospun patterned fiber bundles (SiEP bundles) comprising longitudinally stacked multiple fibers were fabricated, and their capabilities of spatially stimulating the responses of neural cells, including PC12 cells, human neural stem cells (hNSCs), and dorsal root ganglia (DRG), were assessed by comparing them to conventional fibrous matrices having either randomly oriented fibers or individually aligned fibers. The SiEP bundles possessed remarkably distinctive morphological and topographical characteristics: multicomplexed infrastructures with nano- and microscale fibers, rough surfaces, and soft mechanical properties. Importantly, the SiEP bundles resulted in spatial cellular elongations corresponding to the fiber directions and induced highly robust neurite extensions along the patterned fibers. Furthermore, the residence of hNSCs on the topographically rough grooves of the SiEP bundles boosted neuronal differentiation. These findings can provide crucial insights for designing fibrous platforms that can spatially regulate cellular responses and potentially offer powerful strategies for a neural growth system in which directional cellular responses are critical for the functional recovery of damaged neural tissues. PMID:27167566

  1. Sperm bundle and reproductive organs of carabid beetles tribe Pterostichini (Coleoptera: Carabidae)

    NASA Astrophysics Data System (ADS)

    Sasakawa, Kôji

    2007-05-01

    The morphological characteristics of sperm and reproductive organs may offer clues as to how reproductive systems have evolved. In this paper, the morphologies of the sperm and male reproductive organs of carabid beetles in the tribe Pterostichini (Coleoptera: Carabidae) are described, and the morphological associations among characters are examined. All species form sperm bundles in which the head of the sperm was embedded in a rod-shaped structure, i.e., spermatodesm. The spermatodesm shape (left-handed spiral, right-handed spiral, or without conspicuous spiral structure) and the condition of the sperm on the spermatodesm surface (with the tail free-moving or forming a thin, sheetlike structure) vary among species. In all species, the spiral directions of the convoluted seminal vesicles and vasa deferentia are the same on both sides of the body; that is, they show an asymmetric structure. The species in which the sperm bundle and the seminal vesicles both have a spiral structure could be classified into two types, with significant differences in sperm-bundle length between the two types. The species with a sperm-bundle spiral and seminal-vesicle spiral of almost the same diameter have longer sperm bundles than the species with a sperm-bundle spiral and seminal-vesicle tube of almost the same diameter. In the former type, the spiral directions of the sperm bundles and seminal vesicles are inevitably the same, whereas they differ in some species with the later type. Therefore, increased sperm bundle length appears to have been facilitated by the concordance of the sperm bundle’s coiling direction with the coiling direction of the seminal vesicle.

  2. Beta-peptide bundles with fluorous cores.

    PubMed

    Molski, Matthew A; Goodman, Jessica L; Craig, Cody J; Meng, He; Kumar, Krishna; Schepartz, Alanna

    2010-03-24

    We reported recently that certain beta-peptides self-assemble spontaneously into cooperatively folded bundles whose kinetic and thermodynamic metrics mirror those of natural helix bundle proteins. The structures of four such beta-peptide bundles are known in atomic detail. These structures reveal a solvent-sequestered, hydrophobic core stabilized by a unique arrangement of leucine side chains and backbone methylene groups. Here we report that this hydrophobic core can be re-engineered to contain a fluorous subdomain while maintaining the characteristic beta-peptide bundle fold. Like alpha-helical bundles possessing fluorous cores, fluorous beta-peptide bundles are stabilized relative to hydrocarbon analogues and undergo cold denaturation. Beta-peptide bundles with fluorous cores represent the essential first step in the synthesis of orthogonal protein assemblies that can sequester selectively in an interstitial membrane environment. PMID:20196598

  3. Facile synthesis of symmetric bundle-like Sb2S3 micron-structures and their application in lithium-ion battery anodes.

    PubMed

    Yi, Zheng; Han, Qigang; Cheng, Yong; Wu, Yaoming; Wang, Limin

    2016-06-01

    A novel two-step oxidation-sulfuration route is developed to fabricate the symmetric bundle-like Sb2S3 micron-structure, in which hundreds of one-dimensional Sb2S3 nanowires are tied. As an anode material for lithium-ion batteries, the bundle-like Sb2S3 delivers a discharge capacity of 548 mA h g(-1) after 100 cycles, much higher than the rod-like one. PMID:27231231

  4. Quantum Bundles and Their Symmetries

    NASA Astrophysics Data System (ADS)

    Balachandran, A. P.; Marmo, G.; Simoni, A.; Sparano, G.

    Wave functions in the domain of observables such as the Hamiltonian are not always smooth functions on the classical configuration space Q. Rather, they are often best regarded as functions on a G bundle EG over Q or as sections of an associated bundle. If H is a classical group which acts on Q, its quantum version HG, which acts on EG, is not always H, but an extension of H by G. A powerful and physically transparent construction of EG and HG, where G=U(1) and H1(Q, Z)=0, has been developed using the path space {P}. ({P} consists of paths on Q from a fixed point.) In this paper we show how to construct EG and HG when G is U(1) or U(1)×π1(Q) and there is no restriction on H1(Q, Z). The method is illustrated with concrete examples, such as a system of charges and monopoles. We argue also that {P} is a sort of superbundle from which a large variety of bundles can be obtained by imposing suitable equivalence relations.

  5. Gap Structure Effects on Surface-Enhanced Raman Scattering Intensities for Gold Gapped Rods

    SciTech Connect

    Li, Shuzhou Z.; Pedano, Maria L.; Chang, Shih-Hui; Mirkin, Chad A.; Schatz, George C.

    2010-01-01

    Gapped rods provide a unique platform for elucidating structure/function relationships, both for single-molecule electrochemical techniques and for surface-enhanced Raman scattering (SERS). This paper attempts to elucidate the dependence of SERS intensities on gap topography and gap distance for gold gapped rods with segment lengths varying over a wide range (40-2000 nm). Significantly, we have determined that rough gaps lead to a smaller SERS enhancement than smooth gaps for these structures even though the rough gaps have a larger total surface area. Both theory and experiment show periodic variation of SERS intensity with segment length as determined by odd-symmetry plasmon multipoles. Excitation of even-symmetry modes is dipole forbidden (for polarization along the rod axis), but this selection rule can be relaxed by roughness or, for smooth gaps, by near-field coupling between the rod segments.

  6. Understanding flame rods

    SciTech Connect

    McAuley, J.A. Jr.

    1995-11-01

    The flame rod is probably the least understood method of flame detection. Although it is not recommended for oilfired equipment, it is very common on atmospheric, or {open_quotes}in-shot,{close_quotes} gas burners. It is also possible, although not common, to have an application with a constant gas pilot, monitored by a flame rod, and maintaining an oil main flame. Regardless of the application, chances are that flame rods will be encountered during the course of servicing. The technician today must be versatile and able to work on many different types of equipment. One must understand the basic principles of flame rods, and how to correct potential problems. The purpose of a flame detection system is two-fold: (1) to prove there is no flame when there shouldn`t be one, and (2) to prove there is a flame when there should be one. Flame failure response time is very important. This is the amount of time it takes to realize there is a loss of flame, two to four seconds is typical today. Prior to flame rods, either bi-metal or thermocouple type flame detectors were common. The response time for these detectors was up to three minutes, seldom less than one minute.

  7. Simulation of steady-state and transient sodium boiling experiments in a seven-pin bundle under flow rundown conditions by using BODYFIT-1FE code

    SciTech Connect

    Chen, B.C.J.; Sha, W.T.

    1981-01-01

    A seven-pin rod bundle under flow rundown conditions was simulated by using the computer code BODYFIT-1FE (BOunDarY-FITted Coordinate System - 1 phase, Fully-Elliptic). In this code, the complicated rod bundle configuration is first transformed into rectangular geometry with uniform meshes. The transformed governing equations for all the thermal-hydraulic variables are then solved. The results of the simulation are presented here. All the predicted values agree favorably with the measured data. 7 refs., 20 figs.

  8. Random rough surface photofabrication

    NASA Astrophysics Data System (ADS)

    Brissonneau, Vincent; Escoubas, Ludovic; Flory, François; Berginc, Gérard

    2011-10-01

    Random rough surfaces are of primary interest for their optical properties: reducing reflection at the interface or obtaining specific scattering diagram for example. Thus controlling surface statistics during the fabrication process paves the way to original and specific behaviors of reflected optical waves. We detail an experimental method allowing the fabrication of random rough surfaces showing tuned statistical properties. A two-step photoresist exposure process was developed. In order to initiate photoresist polymerization, an energy threshold needs to be reached by light exposure. This energy is brought by a uniform exposure equipment comprising UV-LEDs. This pre-exposure is studied by varying parameters such as optical power and exposure time. The second step consists in an exposure based on the Gray method.1 The speckle pattern of an enlarged scattered laser beam is used to insolate the photoresist. A specific photofabrication bench using an argon ion laser was implemented. Parameters such as exposure time and distances between optical components are discussed. Then, we describe how we modify the speckle-based exposure bench to include a spatial light modulator (SLM). The SLM used is a micromirror matrix known as Digital Micromirror Device (DMD) which allows spatial modulation by displaying binary images. Thus, the spatial beam shape can be tuned and so the speckle pattern on the photoresist is modified. As the photoresist photofabricated surface is correlated to the speckle pattern used to insolate, the roughness parameters can be adjusted.

  9. Intramedullary rodding in osteogenesis imperfecta.

    PubMed

    Mulpuri, K; Joseph, B

    2000-01-01

    The results of intramedullary rodding of long bones of 16 children with osteogenesis imperfecta, over a 10-year period, were analyzed. Sheffield elongating rods or non-elongating rods were used. The frequency of fractures was dramatically reduced after implantation of either type of rod, and the ambulatory status improved in all instances. The results were significantly better after Sheffield rodding with regard to the frequency of complications requiring reoperations and the longevity of the rods. Migration of the rods, encountered frequently, appears to be related to improper placement of the rods in the bone. It seems likely that if care is taken to ensure precise placement of a rod of appropriate size, several of these complications may be avoided. PMID:10739296

  10. COMPOSITE CONTROL ROD

    DOEpatents

    Rock, H.R.

    1963-12-24

    A composite control rod for use in controlling a nuclear reactor is described. The control rod is of sandwich construction in which finned dowel pins are utilized to hold together sheets of the neutron absorbing material and nonabsorbing structural material thereby eliminating the need for being dependent on the absorbing material for structural support. The dowel pins perform the function of absorbing the forces due to differential thermal expansion, seating further with the fins into the sheets of material and crushing before damage is done either to the absorbing or non-absorbing material. (AEC)

  11. Experiment data report for Multirod Burst Test (MRBT) Bundle B-5. [PWR

    SciTech Connect

    Chapman, R H; Crowley, J L; Longest, A W

    1984-08-01

    A reference source of MRBT bundle B-5 test data is presented with interpretation limited to that necessary to understand pertinent features of the test. Primary objectives of this 8 x 8 multirod burst test were to investigate the effects of array size and rod-to-rod interactions on cladding deformation in the high-alpha-Zircaloy temperature range under simulated light-water reactor loss-of-coolant accident (LOCA) conditions. B-5 test conditions, nominally the same as used in an earlier 4 x 4 (B-3) test, simulated the adiabatic heatup (reheat) phase of an LOCA and were conducive to large deformation. The fuel pin simulators were electrically heated (average linear power generation of 3.0 kW/m) and were slightly cooled with a very low flow (Re approx. 140) of low-pressure superheated steam. The cladding temperature increased from the initial temperature (335/sup 0/C) to the burst temperature at a rate of 9.8/sup 0/C/s. The simulators burst in a very narrow temperature range, with an average of 768/sup 0/C. Cladding burst strain ranged from 32% to 95%, with an average of 61%. Volumetric expansion over the heated length of the cladding ranged from 35% to 79%, with an average of 52%. The results clearly show deformation was greater in the bundle interior and suggest rod-to-rod mechanical interactions caused axial propagation of the deformation.

  12. Experimental results of the QUENCH-16 bundle test on air ingress

    SciTech Connect

    Stuckert, J.; Steinbrueck, M.

    2012-07-01

    The out-of-pile bundle experiment QUENCH-16 on air ingress was conducted in the electrically heated 21-rod QUENCH facility at KIT in July 2011. It was performed in the frame of the EC supported LACOMECO program. The test scenario included the oxidation of the Zircaloy-4 claddings in air following a limited pre-oxidation in steam, and involved a long period of oxygen starvation to promote interaction with the nitrogen. The primary aim was to examine the influence of the formed oxide layer structure on bundle coolability and hydrogen release during the terminal flooding phase. QUENCH-16 was thus a companion test to the earlier air ingress experiment, QUENCH-10, which was performed with strongly pre-oxidized bundle. Unlike QUENCH-10, significant temperature escalation and intensive hydrogen release were observed during the reflood phase. Post-test investigations of bundle cross sections reveal residual nitride traces at various elevations. The external part of the oxide scale is of porous structure due to re-oxidation of nitrides during reflood. Relative thick internal oxide scales underneath this porous layer and residual nitrides were formed during reflood. At lower bundle elevations frozen partially oxidized melt was detected, relocated from upper elevations. (authors)

  13. Parallel transport on principal bundles over stacks

    NASA Astrophysics Data System (ADS)

    Collier, Brian; Lerman, Eugene; Wolbert, Seth

    2016-09-01

    In this paper we introduce a notion of parallel transport for principal bundles with connections over differentiable stacks. We show that principal bundles with connections over stacks can be recovered from their parallel transport thereby extending the results of Barrett, Caetano and Picken, and Schreiber and Waldorf from manifolds to stacks. In the process of proving our main result we simplify Schreiber and Waldorf's original definition of a transport functor for principal bundles with connections over manifolds and provide a more direct proof of the correspondence between principal bundles with connections and transport functors.

  14. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    DOE PAGESBeta

    Bakosi, J.; Christon, M. A.; Lowrie, R. B.; Pritchett-Sheats, L. A.; Nourgaliev, R. R.

    2013-07-12

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3 × 3 and 5 × 5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carriedmore » out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.« less

  15. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    SciTech Connect

    Bakosi, J.; Christon, M. A.; Lowrie, R. B.; Pritchett-Sheats, L. A.; Nourgaliev, R. R.

    2013-07-12

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3 × 3 and 5 × 5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.

  16. Determination of Joint Roughness Coefficients Using Roughness Parameters

    NASA Astrophysics Data System (ADS)

    Jang, Hyun-Sic; Kang, Seong-Seung; Jang, Bo-An

    2014-11-01

    This study used precisely digitized standard roughness profiles to determine roughness parameters such as statistical and 2D discontinuity roughness, and fractal dimensions. Our methods were based on the relationship between the joint roughness coefficient (JRC) values and roughness parameters calculated using power law equations. Statistical and 2D roughness parameters, and fractal dimensions correlated well with JRC values, and had correlation coefficients of over 0.96. However, all of these relationships have a 4th profile (JRC 6-8) that deviates by more than ±5 % from the JRC values given in the standard roughness profiles. This indicates that this profile is statistically different than the others. We suggest that fractal dimensions should be measured within the entire range of the divider, instead of merely measuring values within a suitable range. Normalized intercept values also correlated with the JRC values, similarly to the fractal dimension values discussed above. The root mean square first derivative values, roughness profile indexes, 2D roughness parameter, and fractal dimension values decreased as the sampling interval increased. However, the structure function values increased very rapidly with increasing sampling intervals. This indicates that the roughness parameters are not independent of the sampling interval, and that the different relationships between the JRC values and these roughness parameters are dependent on the sampling interval.

  17. Anchor for Fiberglas Guy Rod

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1982-01-01

    Solution to problem of anchoring fiberglas guy rods to install nut with threads on outer circumference, followed by aluminum sleeve. Sleeve has opening oval at upper and round at bottom end. End of rod is split so fiberglas wedge can be inserted to form V-shaped end. Spread end of rod fits into tapered hole in sleeve and threaded aluminum coupling is put over rod and sleeve.

  18. REACTOR CONTROL ROD OPERATING SYSTEM

    DOEpatents

    Miller, G.

    1961-12-12

    A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

  19. RELATIONSHIP BETWEEN THE AERODYNAMIC ROUGHNESS LENGTH AND THE ROUGHNESS DENSITY IN CASES OF LOW ROUGHNESS DENSITY

    EPA Science Inventory

    This paper presents measurements of roughness length performed in a wind tunnel for low roughness density. The experiments were performed with both compact and porous obstacles (clusters), in order to simulate the behavior of sparsely vegetated surfaces.

  20. Hafnium stainless steel absorber rod for control rod

    SciTech Connect

    Charnley, J.E.; Cearley, J.E.; Dixon, R.C.; Izzo, K.R.; Aiello, L.L.

    1989-08-01

    This patent describes an improvement in a control rod having a stainless steel body for enclosing a neutron absorbing poison, the control rod having movement along an axial direction for insertion into and out of a nuclear reactor for controlling a nuclear reaction. The improvement comprising: a piece of hafnium; a piece of stainless steel joined to the hafnium by a thin diffusion interface created by friction welding. The hafnium and the stainless steel oriented serially in the axial direction with the thin diffusion interface disposed normal to the axial direction of the control rod movement; means for confining the hafnium to movement along the axial direction with the control rod; and means for attaching the piece of stainless steel to the remaining portion of the control rod to load the weld therebetween under compression or tension during the control rod movement. Whereby the thin diffusion interface is loaded in tension or compression only upon dynamic movement of the control rod.

  1. Total rod ERG suppression with high dose compassionate Fenretinide usage.

    PubMed

    Marmor, Michael F; Jain, Atul; Moshfeghi, Darius

    2008-11-01

    Fenretinide is a synthetic retinoid that interferes with the attachment of retinol to retinol binding protein. It may inhibit accumulation of A2E and lipofuscin, and is proposed as therapy for Stargardt disease. It is currently used for cancer therapy, and mild depression of rod function and dark adaptation is a side effect at standard dosage. We studied two youngsters (aged between 12 and 13) receiving high doses as compassionate treatment for neuroblastoma: 800 mg daily for 1 out of every 3 weeks, for roughly 2 years. Goldmann-Weekers dark adaptometry, ISCEV standard ERG and mfERG were performed, and blood was analyzed for vitamin A. Neither child complained of night blindness or showed retinal fundus abnormalities. On initial exam, dark adaptation thresholds were elevated by 3 log units, and there were no detectable rod ERG responses. However, cone responses and mfERG were normal. Retesting one subject 3 months after stopping the drug revealed normal rod thresholds (slightly delayed) and low normal rod ERG responses. Serum vitamin A levels were normal from both subjects, but there is no record of whether the samples were drawn during cycles on or off drug. Our study demonstrates that high dose Fenretinide can suppress rod function quite completely, although serum vitamin A and rod function apparently return to normal or near normal levels rapidly once the drug is stopped. It is intriguing that cone function and access to vitamin A seems largely independent of Fenretinide effects on retinol availability. PMID:18523815

  2. SAFETY SYSTEM FOR CONTROL ROD

    DOEpatents

    Paget, J.A.

    1963-05-14

    A structure for monitoring the structural continuity of a control rod foi a neutron reactor is presented. A electric conductor readily breakable under mechanical stress is fastened along the length of the control rod at a plurality of positions and forms a closed circuit with remote electrical components responsive to an open circuit. A portion of the conductor between the control rod and said components is helically wound to allow free and normally unrestricted movement of the segment of conductor secured to the control rod relative to the remote components. Any break in the circuit is indicative of control rod breakage. (AEC)

  3. Locked-wrap fuel rod

    DOEpatents

    Kaplan, Samuel; Chertock, Alan J.; Punches, James R.

    1977-01-01

    A method for spacing fast reactor fuel rods using a wire wrapper improved by orienting the wire-wrapped fuel rods in a unique manner which introduces desirable performance characteristics not attainable by previous wire-wrapped designs. Use of this method in a liquid metal fast breeder reactor results in: (a) improved mechanical performance, (b) improved rod-to-rod contact, (c) reduced steel volume, and (d) improved thermal-hydraulic performance. The method produces a "locked wrap" design which tends to lock the rods together at each of the wire cluster locations.

  4. APPARATUS FOR SHEATHING RODS

    DOEpatents

    Ford, W.K.; Wyatt, M.; Plail, S.

    1961-08-01

    An arrangement is described for sealing a solid body of nuclear fuel, such as a uranium metal rod, into a closelyfitting thin metallic sheath with an internal atmosphere of inert gas. The sheathing process consists of subjecting the sheath, loaded with the nuclear fuel body, to the sequential operations of evacuation, gas-filling, drawing (to entrap inert gas and secure close contact between sheath and body), and sealing. (AEC)

  5. Damping Properties of the Hair Bundle

    NASA Astrophysics Data System (ADS)

    Baumgart, Johannes; Kozlov, Andrei S.; Risler, Thomas; Hudspeth, A. J.

    2011-11-01

    The viscous liquid surrounding a hair bundle dissipates energy and dampens oscillations, which poses a fundamental physical challenge to the high sensitivity and sharp frequency selectivity of hearing. To identify the mechanical forces at play, we constructed a detailed finite-element model of the hair bundle. Based on data from the hair bundle of the bullfrog's sacculus, this model treats the interaction of stereocilia both with the surrounding liquid and with the liquid in the narrow gaps between the individual stereocilia. The investigation revealed that grouping stereocilia in a bundle dramatically reduces the total drag. During hair-bundle deflections, the tip links potentially induce drag by causing small but very dissipative relative motions between stereocilia; this effect is offset by the horizontal top connectors that restrain such relative movements at low frequencies. For higher frequencies the coupling liquid is sufficient to assure that the hair bundle moves as a unit with a low total drag. This work reveals the mechanical characteristics originating from hair-bundle morphology and shows quantitatively how a hair bundle is adapted for sensitive mechanotransduction.

  6. Net order optimization in analog net bundles

    NASA Astrophysics Data System (ADS)

    Jambor, Thomas; Schreiner, Lars; Olbrich, Markus; Barke, Erich

    2005-06-01

    This paper presents a new approach to optimize net order in analog busses. It is used for the PARasitic SYmmetric router (PARSY), which routes net bundles, e.g. busses or differential pairs, maintaining parasitic symmetry and limiting differential coupling. The router is mainly devoted to analog signal interconnect but can also be used for critical digital busses. Net bundles have a fixed order, because wire crossing is not allowed in net bundle segments to enforce symmetry. Wires inside net bundle segments are generated by module generators. Connecting cell terminals to the first or the last net bundle segment is complex, because the cell terminals can vary in geometry and placement. Therefore, an assignment between nets and wires (net order) in a segment is required. This assignment does not affect the order in which nets or net bundles are routed sequentially. The optimization objective for the connections from net bundle segments to terminals is to minimize the number of crossings and the length difference, while maintaining symmetry if possible. Therefore, a net order has to be calculated, which globally optimizes these criteria for all terminal connections. Different net orders can be computed from the placement of terminals, which have to be connected to a net bundle segment. An additional order is calculated from these net orders, which contains the most characteristic features of all net orders. For all net orders costs are evaluated, and the one with the lowest cost is chosen.

  7. Delay Tolerant Networking - Bundle Protocol Simulation

    NASA Technical Reports Server (NTRS)

    SeGui, John; Jenning, Esther

    2006-01-01

    In this paper, we report on the addition of MACHETE models needed to support DTN, namely: the Bundle Protocol (BP) model. To illustrate the useof MACHETE with the additional DTN model, we provide an example simulation to benchmark its performance. We demonstrate the use of the DTN protocol and discuss statistics gathered concerning the total time needed to simulate numerous bundle transmissions.

  8. Fock modules and noncommutative line bundles

    NASA Astrophysics Data System (ADS)

    Landi, Giovanni

    2016-09-01

    To a line bundle over a noncommutative space there is naturally associated a Fock module. The algebra of corresponding creation and annihilation operators is the total space algebra of a principal U(1) -bundle over the noncommutative space. We describe the general construction and illustrate it with examples.

  9. Vortices in vibrated granular rods

    NASA Astrophysics Data System (ADS)

    Neicu, Toni; Kudrolli, Arshad

    2002-03-01

    We report the first experimental observation of vortex patterns in granular rods inside a container that is vibrated vertically . The experiments were carried out with an anodized aluminum circular container which is rigidly attached to an electromagnetic shaker and the patterns are imaged using a high-frame rate digital camera. At low rod numbers and driving amplitudes, the rods are observed to lie horizontally. Above a critical number or packing fraction of rods, moving domains of vertical rods are spontaneously observed to form which coexist with horizontal rods. These small domains of vertical rods coarsen over time to form a few large vortices. The size of the vortices increases with the number of rods. We are able to track the ends of the vertical rods and obtain the velocity fields of the vortices. The mean azimuthal velocity as a function of distance from the center of the vortex is obtained as a function of the packing fraction. We will report the phase diagram of the various patterns observed as function of number of rods and driving amplitude. The mechanism for the formation and motion of the domains of vertical rods will be also discussed.

  10. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small button'' in the latch mechanism had broken off of the lock plunger'' and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  11. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small ``button`` in the latch mechanism had broken off of the ``lock plunger`` and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  12. Optical roughness measurements on specially designed roughness standards

    NASA Astrophysics Data System (ADS)

    Danzl, R.; Helmli, F.; Rubert, P.; Prantl, M.

    2008-09-01

    The measurement of surface texture is one of the most common and important ways to judge the quality of a technical surface. In order to verify whether a metrology device is able to measure certain types of roughness accurately, various roughness standards with calibrated roughness values are available. While almost all roughness standards produced so far have been designed for tactile systems we demonstrate how the optical metrology device InfiniteFocus can be applied to special roughness standards that have been artificially roughened. Experiments are performed on standards with periodic structure and the results of the optical system are compared to the calibrated values obtained by tactile systems with different tip radius. Additionally the profile-based measurements are compared to area-based measurements conform to a recently developed ISO standard draft. Finally roughness measurements on real surfaces are presented.

  13. Line bundle embeddings for heterotic theories

    NASA Astrophysics Data System (ADS)

    Nibbelin, Stefan Groot; Ruehle, Fabian

    2016-04-01

    In heterotic string theories consistency requires the introduction of a non-trivial vector bundle. This bundle breaks the original ten-dimensional gauge groups E8 × E8 or SO(32) for the supersymmetric heterotic string theories and SO(16) × SO(16) for the non-supersymmetric tachyon-free theory to smaller subgroups. A vast number of MSSM-like models have been constructed up to now, most of which describe the vector bundle as a sum of line bundles. However, there are several different ways of describing these line bundles and their embedding in the ten-dimensional gauge group. We recall and extend these different descriptions and explain how they can be translated into each other.

  14. Noise Radiation from Single and Multiple Rod Configurations

    NASA Technical Reports Server (NTRS)

    Hutcheson, Florence V.; Brooks, Thomas F.

    2006-01-01

    Acoustic measurements were performed on single and multiple rod configurations to study the effect of Reynolds number, surface roughness, freestream turbulence, proximity and wake interference on the radiated noise. The Reynolds number ranged from 3.8 x 10(exp 3) to 10(exp 5). Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the different model configurations tested. The dependence of the peak Sound Pressure Level on velocity was also examined. Several concepts for the reduction of the noise radiating from cylindrical rods were tested. It was shown that wire wraps and collar distributions could be used to significantly reduce the noise radiating from rods in tandem configurations.

  15. Influence of non-uniform flow distribution on overall heat transfer in convective bundle of circulating fluidized bed boiler

    NASA Astrophysics Data System (ADS)

    Kalisz, Sylwester; Pronobis, Marek

    2005-09-01

    In the paper the results of comparative investigations on heat transfer performance of boiler convective bundle and its additional surface, i.e. membrane water wall are presented. For this purpose the non-uniform flow field was modelled in an isothermal test stand operated in self-modeling mode. Then the heat transfer characteristics of such arrangement were estimated by means of naphthalene heat/mass transfer analogy technique. The bundle samples in the shape of round bars (rods) were cast with naphthalene and placed in 27 locations in the bundle while water-wall-modeling samples were coated with naphthalene by painting. Both types of samples were exposed to cold air flow. The results were then compared to the mean heat transfer performance of the same bundle exposed to uniform flow field. The differences of approximately 10% were noticed. Moreover, the heat transfer coefficients for additional surface were even three times lower than those of the bundle. In view of results obtained in the work, the commonly made assumption of equality of heat transfer coefficients for both the bundle and its additional surface may lead to certain errors in heat transfer calculations and discrepancies between the calculated values of heating surfaces area and later operational needs of steam generator.

  16. Intranuclear bundles of microfilaments and microtubules in chromaffin cells of the auricle of the heart of a lungfish, Protopterus aethiopicus.

    PubMed

    Scheuermann, D W; Adriaensen, D; De Groodt-Lasseel, M H

    1988-01-01

    Intranuclear microtubular-microfilamentous rod-like inclusions were investigated in chromaffin cells of the auricle of the heart of lungfishes. In conventional electron microscopy, these inclusions reveal a wide variety in appearance, depending on their orientation to the plane of sectioning. Whereas originally they were merely interpreted as a bundle of microfilaments, application of a goniometer stage showed the rod- or spindle-shaped intranuclear inclusions to have a basic substructure of parallel arranged microtubules among microfilaments, which are clearly connected to chromatin granules, occasionally penetrating dense areas of chromatin. The chemical nature and biological significance of these structures, which so far remain enigmatic, are discussed. PMID:3227775

  17. Roughness characteristics of natural channels

    USGS Publications Warehouse

    Barnes, Harry Hawthorne

    1967-01-01

    Color photographs and descriptive data are presented for 50 stream channels for which roughness coefficients have been determined. All hydraulic computations involving flow in open channels require an evaluation of the roughness characteristics of the channel. In the absence of a satisfactory quantitative procedure this evaluation remains chiefly an art. The ability to evaluate roughness coefficients must be developed through experience. One means of gaining this experience is by examining and becoming acquainted with the appearance of some typical channels whose roughness coefficients are known. The photographs and data contained in this report represent a wide range of channel conditions. Familiarity with the appearance, geometry, and roughness characteristics of these channels will improve the engineer's ability to select roughness coefficients for other channels .

  18. Solvation forces between rough surfaces

    SciTech Connect

    Frink, L.J.; van Swol, F.

    1998-04-01

    We investigate the role of surface roughness on solvation forces and solvation free energies. Roughness is introduced by dividing a surface into an array of square tiles that are then randomly displaced in the direction perpendicular to the wall. The integrated wall strength of these tiled surfaces is independent of the surface roughness and hence this class of rough walls is ideally suited for isolating roughness effects. We use grand canonical Monte Carlo simulations of a Lennard-Jones fluid confined in a slit pore with rough walls to generate the solvation interactions as a function of roughness, tile size, and surface area. The simulation data are compared to a simple superposition approximation of smooth wall solvation interactions (obtained from simulation or density functional theory), based on a distribution of wall separations. We find that this approximation provides a surprisingly accurate route to the solvation interaction of rough surfaces. In general, increased roughness leads to a reduction of oscillations in the solvation forces and surface free energies. However, nonmonotonic behavior of the oscillation amplitude with roughness can be observed for finite surfaces. The washing out of the oscillations found for large surface roughness produces a solvation force that exhibits a broad repulsive peak with separation. The broad repulsion is a consequence of the resistance to squeezing out fluid from the smallest gaps between two opposing rough surfaces. It is as much a reflection of packing effects as are the solvation oscillations for perfectly smooth pores. In addition, we present results for patterned and undulating surfaces produced by an analogous modification of the one-body external field for smooth walls. Finally, we discuss the implications of our results for a number of experimental systems including self-assembled monolayers, microporous materials, protein solutions, and DNA crystals. {copyright} {ital 1998 American Institute of Physics.}

  19. Temperature Distributions in LMR Fuel Pin Bundles as Modeled by COBRA-IV-I

    NASA Astrophysics Data System (ADS)

    Wright, Steven A.; Stout, Sherry

    2005-02-01

    Most pin type reactor designs for space power or terrestrial applications group the fuel pins into a number of relatively large fuel pin bundles or subassemblies. Fuel bundles for terrestrial liquid metal fast breeders reactors typically use 217 - 271 pins per sub-assembly, while some SP100 designs use up to 331 pins in a central subassembly that was surrounded by partial assemblies. Because thermal creep is exponentially related to temperature, small changes in fuel pin cladding temperature can make large differences in the lifetime in a high temperature liquid metal reactor (LMR). This paper uses the COBRA-IV-I computer code to determine the temperature distribution within LMR fuel bundles. COBRA-IV-I uses the sub-channel analysis approach to determine the enthalpy (or temperature) and flow distribution in rod bundles for both steady-state and transient conditions. The COBRA code runs in only a few seconds and has been benchmarked and tested extensively over a wide range of flow conditions. In this report the flow and temperature distributions for two types of lithium cooled space reactor core designs were calculated. One design uses a very tight fuel pin packing that has a pitch to diameter ratio of 1.05 (small wire wrap with a diameter of 392 μm) as proposed in SP100. The other design uses a larger pitch to diameter ratio of 1.09 with a larger more conventional sized wire wrap diameter of 1 mm. The results of the COBRA pin bundle calculations show that the larger pitch-to-diameter fuel bundle designs are more tolerant to local flow blockages, and in addition they are less sensitive to mal-flow distributions that occur near the edges of the subassembly.

  20. Temperature Distributions in LMR Fuel Pin Bundles as Modeled by COBRA-IV-I

    SciTech Connect

    Wright, Steven A.; Stout, Sherry

    2005-02-06

    Most pin type reactor designs for space power or terrestrial applications group the fuel pins into a number of relatively large fuel pin bundles or subassemblies. Fuel bundles for terrestrial liquid metal fast breeders reactors typically use 217 - 271 pins per sub-assembly, while some SP100 designs use up to 331 pins in a central subassembly that was surrounded by partial assemblies. Because thermal creep is exponentially related to temperature, small changes in fuel pin cladding temperature can make large differences in the lifetime in a high temperature liquid metal reactor (LMR). This paper uses the COBRA-IV-I computer code to determine the temperature distribution within LMR fuel bundles. COBRA-IV-I uses the sub-channel analysis approach to determine the enthalpy (or temperature) and flow distribution in rod bundles for both steady-state and transient conditions. The COBRA code runs in only a few seconds and has been benchmarked and tested extensively over a wide range of flow conditions. In this report the flow and temperature distributions for two types of lithium cooled space reactor core designs were calculated. One design uses a very tight fuel pin packing that has a pitch to diameter ratio of 1.05 (small wire wrap with a diameter of 392 {mu}m) as proposed in SP100. The other design uses a larger pitch to diameter ratio of 1.09 with a larger more conventional sized wire wrap diameter of 1 mm. The results of the COBRA pin bundle calculations show that the larger pitch-to-diameter fuel bundle designs are more tolerant to local flow blockages, and in addition they are less sensitive to mal-flow distributions that occur near the edges of the subassembly.

  1. Roughness Measurement of Dental Materials

    NASA Astrophysics Data System (ADS)

    Shulev, Assen; Roussev, Ilia; Karpuzov, Simeon; Stoilov, Georgi; Ignatova, Detelina; See, Constantin von; Mitov, Gergo

    2016-06-01

    This paper presents a roughness measurement of zirconia ceramics, widely used for dental applications. Surface roughness variations caused by the most commonly used dental instruments for intraoral grinding and polishing are estimated. The applied technique is simple and utilizes the speckle properties of the scattered laser light. It could be easily implemented even in dental clinic environment. The main criteria for roughness estimation is the average speckle size, which varies with the roughness of zirconia. The algorithm used for the speckle size estimation is based on the normalized autocorrelation approach.

  2. Aerosol behavior during SIC control rod failure in QUENCH-13 test

    NASA Astrophysics Data System (ADS)

    Lind, Terttaliisa; Csordás, Anna Pintér; Nagy, Imre; Stuckert, Juri

    2010-02-01

    In a nuclear reactor severe accident, radioactive fission products as well as structural materials are released from the core by evaporation, and the released gases form particles by nucleation and condensation. In addition, aerosol particles may be generated by droplet formation and fragmentation of the core. In pressurized water reactors (PWR), a commonly used control rod material is silver-indium-cadmium (SIC) covered with stainless steel cladding. The control rod elements, Cd, In and Ag, have relatively low melting temperatures, and especially Cd has also a very low boiling point. Control rods are likely to fail early on in the accident due to melting of the stainless steel cladding which can be accelerated by eutectic interaction between stainless steel and the surrounding Zircaloy guide tube. The release of the control rod materials would follow the cladding failure thus affecting aerosol source term as well as fuel rod degradation. The QUENCH experimental program at Forschungszentrum Karlsruhe investigates phenomena associated with reflood of a degrading core under postulated severe accident conditions. QUENCH-13 test was the first in this program to include a silver-indium-cadmium control rod of prototypic PWR design. To characterize the extent of aerosol release during the control rod failure, aerosol particle size distribution and concentration measurements in the off-gas pipe of the QUENCH facility were carried out. For the first time, it was possible to determine on-line the aerosol concentration and size distribution released from the core. These results are of prime importance for model development for the proper calculation of the source term resulting from control rod failure. The on-line measurement showed that the main aerosol release started at the bundle temperature maximum of T ˜ 1570 K at hottest bundle elevation. A very large burst of aerosols was detected 660 s later at the bundle temperature maximum of T ˜ 1650 K, followed by a relatively

  3. Preliminary report: NIF laser bundle review

    SciTech Connect

    Tietbohl, G.L.; Larson, D.W.; Erlandson, A.C.

    1995-08-31

    As requested in the guidance memo {sup 1}, this committe determined whether there are compelling reasons to recommend a change from the NIF CDR baseline laser. The baseline bundle design based on a tradeoff between cost and technical risk, which is replicated four times to create the required 192 beams. The baseline amplifier design uses bottom loading 1{times}4 slab and flashlamp cassettes for amplifier maintenance and large vacuum enclosures (2.5m high {times} 7m wide in cross-section for each of the two spatial filters in each of the four bundles. The laser beams are arranged in two laser bays configured in a u-shape around the target area. The entire bundle review effort was performed in a very short time (six weeks) and with limited resources (15 personnel part-time). This should be compared to the effort that produced the CDR design (12 months, 50 to 100 personnel). This committee considered three alternate bundle configurations (2{times}2, 4{times}2, and 4{times}4 bundles), and evaluated each bundle against the baseline design using the seven requested issues in the guidance memo: Cost; schedule; performance risk; maintainability/operability; hardware failure cost exposure; activation; and design flexibility. The issues were reviewed to identify differences between each alternate bundle configuration and the baseline.

  4. Prioritary omalous bundles on Hirzebruch surfaces

    NASA Astrophysics Data System (ADS)

    Aprodu, Marian; Marchitan, Marius

    2016-01-01

    An irreducible algebraic stack is called unirational if there exists a surjective morphism, representable by algebraic spaces, from a rational variety to an open substack. We prove unirationality of the stack of prioritary omalous bundles on Hirzebruch surfaces, which implies also the unirationality of the moduli space of omalous H-stable bundles for any ample line bundle H on a Hirzebruch surface (compare with Costa and Miro-Ŕoig, 2002). To this end, we find an explicit description of the duals of omalous rank-two bundles with a vanishing condition in terms of monads. Since these bundles are prioritary, we conclude that the stack of prioritary omalous bundles on a Hirzebruch surface different from P1 ×P1 is dominated by an irreducible section of a Segre variety, and this linear section is rational (Ionescu, 2015). In the case of the space quadric, the stack has been explicitly described by N. Buchdahl. As a main tool we use Buchdahl's Beilinson-type spectral sequence. Monad descriptions of omalous bundles on hypersurfaces in P4, Calabi-Yau complete intersection, blowups of the projective plane and Segre varieties have been recently obtained by A.A. Henni and M. Jardim (Henni and Jardim, 2013), and monads on Hirzebruch surfaces have been applied in a different context in Bartocci et al. (2015).

  5. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

    A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

  6. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K.

    1982-01-01

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  7. Contraction of cross-linked actomyosin bundles

    NASA Astrophysics Data System (ADS)

    Yoshinaga, Natsuhiko; Marcq, Philippe

    2012-08-01

    Cross-linked actomyosin bundles retract when severed in vivo by laser ablation, or when isolated from the cell and micromanipulated in vitro in the presence of ATP. We identify the timescale for contraction as a viscoelastic time τ, where the viscosity is due to (internal) protein friction. We obtain an estimate of the order of magnitude of the contraction time τ ≈ 10-100 s, consistent with available experimental data for circumferential microfilament bundles and stress fibers. Our results are supported by an exactly solvable, hydrodynamic model of a retracting bundle as a cylinder of isotropic, active matter, from which the order of magnitude of the active stress is estimated.

  8. Actively Contracting Bundles of Polar Filaments

    NASA Astrophysics Data System (ADS)

    Kruse, K.; Jülicher, F.

    2000-08-01

    We introduce a phenomenological model to study the properties of bundles of polar filaments which interact via active elements. The stability of the homogeneous state, the attractors of the dynamics in the unstable regime, and the tensile stress generated in the bundle are discussed. We find that the interaction of parallel filaments can induce unstable behavior and is responsible for active contraction and tension in the bundle. The interaction between antiparallel filaments leads to filament sorting. Our model could apply to simple contractile structures in cells such as stress fibers.

  9. Requirements for contractility in disordered cytoskeletal bundles

    NASA Astrophysics Data System (ADS)

    Lenz, Martin; Gardel, Margaret L.; Dinner, Aaron R.

    2012-03-01

    Actomyosin contractility is essential for biological force generation, and is well understood in highly organized structures such as striated muscle. Additionally, actomyosin bundles devoid of this organization are known to contract both in vivo and in vitro, which cannot be described by standard muscle models. To narrow down the search for possible contraction mechanisms in these systems, we investigate their microscopic symmetries. We show that contractile behavior requires non-identical motors that generate large-enough forces to probe the nonlinear elastic behavior of F-actin. This suggests a role for filament buckling in the contraction of these bundles, consistent with recent experimental results on reconstituted actomyosin bundles.

  10. Making Highly Pure Glass Rods

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.

    1986-01-01

    Proposed quasi-containerless method for making glass rods or fibers minimizes contact between processing equipment and product. Method allows greater range of product sizes and shapes than achieved in experiments on containerless processing. Molten zone established in polycrystalline rod. Furnace sections separated, and glass rod solidifies between them. Clamp supports solid glass as it grows in length. Pulling clamp rapidly away from melt draws glass fiber. Fiber diameter controlled by adjustment of pulling rate.

  11. Automatic safety rod for reactors

    DOEpatents

    Germer, John H.

    1988-01-01

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  12. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  13. Interaction of Failed Fuel Rods Under Air Ingress Conditions

    SciTech Connect

    Hozer, Zoltan; Windberg, Peter; Nagy, Imre; Maroti, Laszlo; Matus, Lajos; Horvath, Marta; Csordas, Anna Pinter; Balasko, Marton; Czitrovszky, Aladar; Jani, Peter

    2003-03-15

    In the late phase of a severe reactor accident, the molten corium interacts with the vessel wall, and it can lead to the failure of the lower head. Through the failed bottom wall, part of the corium can flow into the cavity, and air can enter the primary circuit. The residual fuel in the core periphery will be further oxidized in air atmosphere. The degradation process will accelerate, and new chemical species will be formed, which can have an impact on the release of radioactive materials.Two experiments were carried out with electrically heated nine-rod pressurized water reactor-type bundles in the CODEX (COre Degradation EXperiment) facility to provide experimental data on the behavior of real fuel bundles under air oxidation conditions. The main objective of the tests was the investigation of oxidation phenomena, and some other important aspects (e.g., enhanced fission product release) were not addressed.The CODEX air ingress tests indicated the acceleration of oxidation phenomena and core degradation processes during the late phase of the vessel melt through accident, when air can have access to the residual fuel bundles in the reactor core. The degradation process was accompanied with zirconium-nitride formation and release of uranium-rich aerosols.

  14. 85 µm core rod fiber amplifier delivering 350 W/m

    NASA Astrophysics Data System (ADS)

    Johansen, Mette M.; Michieletto, Mattia; Kristensen, Torben; Alkeskjold, Thomas T.; Lægsgaard, Jesper

    2016-03-01

    An improved version of the distributed modal filtering (DMF) rod fiber is tested in a high power setup delivering 350 W/m of extracted signal average power limited by the available pump power. The rod fiber is thoroughly tested to record the transverse modal instability (TMI) behavior and also measure degradation of the TMI threshold with operation time due to induced absorption in the active material increasing the thermo-optical heat load. Multiple testing degrades the rod fiber and TMI threshold from >360 W to a saturated power level of roughly 240 W.

  15. Characteristic classes associated to Q-bundles

    NASA Astrophysics Data System (ADS)

    Kotov, Alexei; Strobl, Thomas

    2015-10-01

    A Q-manifold is a graded manifold endowed with a vector field of degree 1 squaring to zero. We consider the notion of a Q-bundle, that is, a fiber bundle in the category of Q-manifolds. To each homotopy class of "gauge fields" (sections in the category of graded manifolds) and each cohomology class of a certain subcomplex of forms on the fiber we associate a cohomology class on the base. As any principal bundle yields canonically a Q-bundle, this construction generalizes Chern-Weil classes. Novel examples include cohomology classes that are locally de Rham differential of the integrands of topological sigma models obtained by the AKSZ-formalism in arbitrary dimensions. For Hamiltonian Poisson fibrations one obtains a characteristic 3-class in this manner. We also relate the framework to equivariant cohomology and Lecomte's characteristic classes of exact sequences of Lie algebras.

  16. Quantum Bundle Description of Quantum Projective Spaces

    NASA Astrophysics Data System (ADS)

    Ó Buachalla, Réamonn

    2012-12-01

    We realise Heckenberger and Kolb's canonical calculus on quantum projective ( N - 1)-space C q [ C p N-1] as the restriction of a distinguished quotient of the standard bicovariant calculus for the quantum special unitary group C q [ SU N ]. We introduce a calculus on the quantum sphere C q [ S 2 N-1] in the same way. With respect to these choices of calculi, we present C q [ C p N-1] as the base space of two different quantum principal bundles, one with total space C q [ SU N ], and the other with total space C q [ S 2 N-1]. We go on to give C q [ C p N-1] the structure of a quantum framed manifold. More specifically, we describe the module of one-forms of Heckenberger and Kolb's calculus as an associated vector bundle to the principal bundle with total space C q [ SU N ]. Finally, we construct strong connections for both bundles.

  17. Robust incoherent fiber optic bundle decoder

    NASA Technical Reports Server (NTRS)

    Roberts, Hilary E. (Inventor); DePlachett, Charles P. (Inventor); Deason, Brent E. (Inventor); Pilgrim, Robert A. (Inventor); Sanford, Harold S. (Inventor)

    2003-01-01

    Apparatus and method for calibrating an incoherent fiber optic bundle for use in transmitting visual or infrared coherent images. The apparatus includes a computer, a computer video monitor, an objective lens adjacent to the input end of the bundle, a second lens adjacent the output end of the bundle, and a CCD camera. The camera transmits video data to the monitor to produce an illuminated fiber optic image. The coordinates for the center of each fiber is found through an imaging process and the output fibers coordinates are related to the input fiber coordinates and processed in the computer to produce a mapping lookup-table (LUT) unique to the specific fiber bundle. Remapping of the LUT due to changes in the lens focus, CCD camera, or the addition of an infrared filter is accomplished by a software utility in the computer.

  18. Generalizing roughness: experiments with flow-oriented roughness

    NASA Astrophysics Data System (ADS)

    Trevisani, Sebastiano

    2015-04-01

    Surface texture analysis applied to High Resolution Digital Terrain Models (HRDTMs) improves the capability to characterize fine-scale morphology and permits the derivation of useful morphometric indexes. An important indicator to be taken into account in surface texture analysis is surface roughness, which can have a discriminant role in the detection of different geomorphic processes and factors. The evaluation of surface roughness is generally performed considering it as an isotropic surface parameter (e.g., Cavalli, 2008; Grohmann, 2011). However, surface texture has often an anisotropic character, which means that surface roughness could change according to the considered direction. In some applications, for example involving surface flow processes, the anisotropy of roughness should be taken into account (e.g., Trevisani, 2012; Smith, 2014). Accordingly, we test the application of a flow-oriented directional measure of roughness, computed considering surface gravity-driven flow. For the calculation of flow-oriented roughness we use both classical variogram-based roughness (e.g., Herzfeld,1996; Atkinson, 2000) as well as an ad-hoc developed robust modification of variogram (i.e. MAD, Trevisani, 2014). The presented approach, based on a D8 algorithm, shows the potential impact of considering directionality in the calculation of roughness indexes. The use of flow-oriented roughness could improve the definition of effective proxies of impedance to flow. Preliminary results on the integration of directional roughness operators with morphometric-based models, are promising and can be extended to more complex approaches. Atkinson, P.M., Lewis, P., 2000. Geostatistical classification for remote sensing: an introduction. Computers & Geosciences 26, 361-371. Cavalli, M. & Marchi, L. 2008, "Characterization of the surface morphology of an alpine alluvial fan using airborne LiDAR", Natural Hazards and Earth System Science, vol. 8, no. 2, pp. 323-333. Grohmann, C

  19. Sealed fiber-optic bundle feedthrough

    DOEpatents

    Tanner, Carol E.

    2002-01-01

    A sealed fiber-optic bundle feedthrough by which a multitude of fiber-optic elements may be passed through an opening or port in a wall or structure separating two environments at different pressures or temperatures while maintaining the desired pressure or temperature in each environment. The feedthrough comprises a rigid sleeve of suitable material, a bundle of individual optical fibers, and a resin-based sealing material that bonds the individual optical fibers to each other and to the rigid sleeve.

  20. Visual transduction in human rod photoreceptors.

    PubMed Central

    Kraft, T W; Schneeweis, D M; Schnapf, J L

    1993-01-01

    1. Photocurrents were recorded with suction electrodes from rod photoreceptors of seven humans. 2. Brief flashes of light evoked transient outward currents of up to 20 pA. With increasing light intensity the peak response amplitude increased along an exponential saturation function. A half-saturating peak response was evoked by approximately sixty-five photoisomerizations. 3. Responses to brief dim flashes rose to a peak in about 200 ms. The waveform was roughly like the impulse response of a series of four to five low-pass filters. 4. The rising phases of the responses to flashes of increasing strength were found to fit with a biochemical model of phototransduction with an 'effective delay time' and 'characteristic time' of about 2 and 800 ms, respectively. 5. Spectral sensitivities were obtained over a wavelength range from 380 to 760 nm. The action spectrum, which peaked at 495 nm, followed the template described for photoreceptors in the macaque retina. Variation between rods in the position of the spectrum on the wavelength axis was small. 6. The scotopic luminosity function derived from human psychophysical experiments was found to agree well with the measured rod action spectrum after adjustments were made for lens absorption and photopigment self-screening in the intact eye. 7. Responses to steps of light rose monotonically to a maintained level, showing little or no relaxation. Nevertheless, the relationship between light intensity and steady-state response amplitude was shallower than that expected from simple response saturation. This is consistent with an adaptation mechanism acting on a rapid time scale. 8. Flash sensitivity fell with increasing intensities of background light according to Weber's law. Sensitivity was reduced twofold by lights evoking about 120 photoisomerizations per second. Background lights decreased the time to peak and the integration time of the flash response by up to 20%. PMID:8229828

  1. Simulating Topological Defects in Twisted Fiber Bundles

    NASA Astrophysics Data System (ADS)

    Bruss, Isaac R.; Grason, Gregory M.

    2012-02-01

    Twisted bundles are a common motif found in naturally occurring structures of self-assembled fibers, such as collagen and fibrin. By understanding the general principles governing such organizations, new synthetic materials--from the nano to the macroscale--may also be realized. Recently, continuum elasticity theory has been applied to describe generic twisted fiber bundles. This has revealed a relation between a bundle's twist and the presence of topological defects in the cross-sectional packing of the fibers. Here we employ numerical simulations to examine this interdependence. We model a bundle's cross-section as beads confined to a plane. The interactions between beads is governed by a modified Lennard-Jones potential that accounts for the effects of twist. We observe configurations that range from perfect hexagonal packing for cases of no twist, to defect populated structures above a critical amount of twist. For small bundles of less than ˜100 beads, there exists a discrete spectrum of energy ground states corresponding to integer numbers of five-fold disclinations. For larger bundles, we hope to uncover what types of defect arrangements effectively screen the stresses caused by twist, and compare these to current predictions of the internal organization of collagen fibrils.

  2. Mechanical behavior of enamel rods under micro-compression.

    PubMed

    Yilmaz, Ezgi D; Schneider, Gerold A

    2016-10-01

    Exploring the structural strategies behind the optimized mechanical performance of hierarchical materials has been a focal point of extensive research over the past decades. Dental enamel is one such natural material, comprising a complicated hierarchical structure with a high level of mineral content. Bundles of hydroxyapatite nanofibers (level-1) Ø: 50nm form enamel rods (level-2) Ø: 5µm, which constitute bands (level-3) Ø: 50µm. While a number of studies in the last decade using advanced fracture mechanical methods have revealed an increasing trend in the fracture toughness of enamel with each additional level of hierarchy, there is still no general agreement on how hierarchical structuring affects the stiffness and strength of enamel. In this study, we identified the stiffness and strength values of the isolated rods (level-2) via micro-compression. The rods were tested in three different orientations with respect to the loading direction: parallel, perpendicular and oblique. The highest stress level withstood before catastrophic fracture was observed to be ~1500MPa in perpendicular orientation. In the oblique loading, the specimens failed by shearing and exhibited a damage-tolerant deformation behavior, which was attributed to the conjugation spots identified between the rods and interrod sheets. The elastic modulus was ~60GPa on average and similar in all orientations. The isotropy in stiffness was attributed to the mineral contacts residing between rods. This was verified by an analytical model derived for level-1 and extended over higher hierarchical levels. The experimental results obtained at level-2 were comparable to the compressive strength and stiffness values reported for level-1 and bulk enamel in the literature. In general, our results suggest that hierarchy has only a minor influence on the compressive properties of enamel. PMID:27415405

  3. Composite Lightning Rods for Aircraft

    NASA Technical Reports Server (NTRS)

    Bryan, Charles F., Jr.

    1986-01-01

    Composite, lightweight sacrificial tip with graphite designed reduces lightning-strike damage to composite parts of aircraft and dissipates harmful electrical energy. Device consists of slender composite rod fabricated from highly-conductive unidirectional reinforcing fibers in matrix material. Rods strategically installed in trailing edges of aircraft wings, tails, winglets, control surfaces, and rearward-most portion of aft fuselage.

  4. Rod Climbing of Suspensions

    NASA Astrophysics Data System (ADS)

    Guo, Youjing; Wang, Xiaorong

    We wish to report an unexpected effect observed for particle suspensions sucked to pass through a vertical pipe. Above a critical concentration, the suspension on the outside of the pipe may climb along the outside wall of the pipe and then display a surprising rod-climbing effect. Our study shows that the phenomenon is influenced mainly by the suspension composition, the pipe dimension and the suction speed. The effects of the pipe materials of different kinds are negligible. Increasing the suction force and the concentration increases the climbing height. Increasing the pipe diameter and wall thickness reduces the climbing effect. This behavior may be relevant to that the suspensions of the type described are all displaying markedly shear-thickening.

  5. Rod-to-Globule Transition of pDNA/PEG-Poly(l-Lysine) Polyplex Micelles Induced by a Collapsed Balance Between DNA Rigidity and PEG Crowdedness.

    PubMed

    Tockary, Theofilus A; Osada, Kensuke; Motoda, Yusuke; Hiki, Shigehiro; Chen, Qixian; Takeda, Kaori M; Dirisala, Anjaneyulu; Osawa, Shigehito; Kataoka, Kazunori

    2016-03-01

    The role of poly(ethylene-glycol) (PEG) in rod-shaped polyplex micelle structures, having a characteristic core of folded plasmid DNA (pDNA) and a shell of tethered PEG chains, is investigated using PEG-detachable polyplex micelles. Rod shapes undergo change to compacted globule shapes by removal of PEG from polyplex micelles prepared from block copolymer with acid-labile linkage between PEG and poly(l-lysine) (PLys) through exposure to acidic milieu. This structural change supports the previous investigation on the rod shapes that PEG shell prevents the DNA structure from being globule shaped as the most favored structure in minimizing surface area. Noteworthy, despite the PEG is continuously depleted, the structural change does not occur in gradual shortening manner but the rod shapes keep their length unchanged and abruptly transform into globule shapes. Analysis of PEG density reveals the transition occurred when tethered PEG of rod shapes has decreased to a critical crowdedness, i.e., discontacted with neighboring PEG, which eventually illuminates another contribution, rigidity of DNA packaged as bundle in the rod shapes, in addition to the steric repulsion of PEG, in sustaining rod shapes. This investigation affirms significant role of PEG and also DNA rigidity as bundle in the formation of rod-shaped structures enduring the quest of compaction of charge-neutralized DNA in the polyplex micelles. PMID:26426541

  6. Does surface roughness amplify wetting?

    SciTech Connect

    Malijevský, Alexandr

    2014-11-14

    Any solid surface is intrinsically rough on the microscopic scale. In this paper, we study the effect of this roughness on the wetting properties of hydrophilic substrates. Macroscopic arguments, such as those leading to the well-known Wenzel's law, predict that surface roughness should amplify the wetting properties of such adsorbents. We use a fundamental measure density functional theory to demonstrate the opposite effect from roughness for microscopically corrugated surfaces, i.e., wetting is hindered. Based on three independent analyses we show that microscopic surface corrugation increases the wetting temperature or even makes the surface hydrophobic. Since for macroscopically corrugated surfaces the solid texture does indeed amplify wetting there must exist a crossover between two length-scale regimes that are distinguished by opposite response on surface roughening. This demonstrates how deceptive can be efforts to extend the thermodynamical laws beyond their macroscopic territory.

  7. Measuring Roughnesses Of Optical Surfaces

    NASA Technical Reports Server (NTRS)

    Coulter, Daniel R.; Al-Jumaily, Gahnim A.; Raouf, Nasrat A.; Anderson, Mark S.

    1994-01-01

    Report discusses use of scanning tunneling microscopy and atomic force microscopy to measure roughnesses of optical surfaces. These techniques offer greater spatial resolution than other techniques. Report notes scanning tunneling microscopes and atomic force microscopes resolve down to 1 nm.

  8. Buckling Behavior of Individual and Bundled Microtubules

    PubMed Central

    Soheilypour, Mohammad; Peyro, Mohaddeseh; Peter, Stephen J.; Mofrad, Mohammad R.K.

    2015-01-01

    As the major structural constituent of the cytoskeleton, microtubules (MTs) serve a variety of biological functions that range from facilitating organelle transport to maintaining the mechanical integrity of the cell. Neuronal MTs exhibit a distinct configuration, hexagonally packed bundles of MT filaments, interconnected by MT-associated protein (MAP) tau. Building on our previous work on mechanical response of axonal MT bundles under uniaxial tension, this study is focused on exploring the compression scenarios. Intracellular MTs carry a large fraction of the compressive loads sensed by the cell and therefore, like any other column-like structure, are prone to substantial bending and buckling. Various biological activities, e.g., actomyosin contractility and many pathological conditions are driven or followed by bending, looping, and buckling of MT filaments. The coarse-grained model previously developed in our lab has been used to study the mechanical behavior of individual and bundled in vivo MT filaments under uniaxial compression. Both configurations show tip-localized, decaying, and short-wavelength buckling. This behavior highlights the role of the surrounding cytoplasm and MAP tau on MT buckling behavior, which allows MT filaments to bear much larger compressive forces. It is observed that MAP tau interconnections improve this effect by a factor of two. The enhanced ability of MT bundles to damp buckling waves relative to individual MT filaments, may be interpreted as a self-defense mechanism because it helps axonal MTs to endure harsher environments while maintaining their function. The results indicate that MT filaments in a bundle do not buckle simultaneously implying that the applied stress is not equally shared among the MT filaments, that is a consequence of the nonuniform distribution of MAP tau proteins along the bundle length. Furthermore, from a pathological perspective, it is observed that axonal MT bundles are more vulnerable to failure in

  9. Nerve Bundles and Deep Dyspareunia in Endometriosis.

    PubMed

    Williams, Christina; Hoang, Lien; Yosef, Ali; Alotaibi, Fahad; Allaire, Catherine; Brotto, Lori; Fraser, Ian S; Bedaiwy, Mohamed A; Ng, Tony L; Lee, Anna F; Yong, Paul J

    2016-07-01

    The etiology of deep dyspareunia in endometriosis is unclear. Our objective was to determine whether nerve bundle density in the cul-de-sac/uterosacrals (zone II) is associated with deep dyspareunia in women with endometriosis. We conducted a blinded retrospective immunohistochemistry study (n = 58) at a tertiary referral center (2011-2013). Patients were stringently phenotyped into a study group and 2 control groups. The study group (tender endometriosis, n = 29) consisted of patients with deep dyspareunia, a tender zone II on examination, and an endometriosis lesion in zone II excised at surgery. Control group 1 (nontender endometriosis, n = 17) consisted of patients without deep dyspareunia, a nontender zone II on examination, and an endometriosis lesion in zone II excised at surgery. Control group 2 (tender nonendometriosis, n = 12) consisted of patients with deep dyspareunia, a tender zone II on examination, and a nonendometriosis lesion (eg, normal histology) in zone II excised at surgery. Protein gene product 9.5 (PGP9.5) immunohistochemistry was performed to identify nerve bundles (nerve fibers surrounded by perineurium) in the excised zone II lesion. PGP9.5 nerve bundle density (bundles/high powered field [HPF]) was then scored by a pathologist blinded to the group. We found a significant difference in PGP9.5 nerve bundle density between the 3 groups (analysis of variance, F2,55 = 6.39, P = .003). Mean PGP9.5 nerve bundle density was significantly higher in the study group (1.16 ± 0.56 bundles/HPF [±standard deviation]) compared to control group 1 (0.65 ± 0.36, Tukey test, P = .005) and control group 2 (0.72 ± 0.56, Tukey test, P = .044). This study provides evidence that neurogenesis in the cul-de-sac/uterosacrals may be an etiological factor for deep dyspareunia in endometriosis. PMID:26711313

  10. Mechanism of Actin Filament Bundling by Fascin

    SciTech Connect

    Jansen, Silvia; Collins, Agnieszka; Yang, Changsong; Rebowski, Grzegorz; Svitkina, Tatyana; Dominguez, Roberto

    2013-03-07

    Fascin is the main actin filament bundling protein in filopodia. Because of the important role filopodia play in cell migration, fascin is emerging as a major target for cancer drug discovery. However, an understanding of the mechanism of bundle formation by fascin is critically lacking. Fascin consists of four {beta}-trefoil domains. Here, we show that fascin contains two major actin-binding sites, coinciding with regions of high sequence conservation in {beta}-trefoil domains 1 and 3. The site in {beta}-trefoil-1 is located near the binding site of the fascin inhibitor macroketone and comprises residue Ser-39, whose phosphorylation by protein kinase C down-regulates actin bundling and formation of filopodia. The site in {beta}-trefoil-3 is related by pseudo-2-fold symmetry to that in {beta}-trefoil-1. The two sites are {approx}5 nm apart, resulting in a distance between actin filaments in the bundle of {approx}8.1 nm. Residue mutations in both sites disrupt bundle formation in vitro as assessed by co-sedimentation with actin and electron microscopy and severely impair formation of filopodia in cells as determined by rescue experiments in fascin-depleted cells. Mutations of other areas of the fascin surface also affect actin bundling and formation of filopodia albeit to a lesser extent, suggesting that, in addition to the two major actin-binding sites, fascin makes secondary contacts with other filaments in the bundle. In a high resolution crystal structure of fascin, molecules of glycerol and polyethylene glycol are bound in pockets located within the two major actin-binding sites. These molecules could guide the rational design of new anticancer fascin inhibitors.

  11. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  12. Preliminary design report for the prototypical fuel rod consolidation system

    SciTech Connect

    Rosa, J.M.

    1986-12-03

    This report documents NUTECH's preliminary design of a dry, spent fuel rod consolidation system. This preliminary design is the result of Phase I of a planned four phase project. The present report on this project provides a considerable amount of detail for a preliminary design effort. The design and all of its details are described in this Preliminary Design Report (PDR). The NUTECH dry rod consolidation system described herein is remotely operated. It provides for automatic operation, but with operator hold points between key steps in the process. The operator has the ability to switch to a manual operation mode at any point in the process. The system is directed by the operator using an executive computer which controls and coordinates the operation of the in-cell equipment. The operator monitors the process using an in-cell closed circuit television (CCTV) system with audio output and equipment status displays on the computer monitor. The in-cell mechanical equipment consists of the following: (1) two overhead cranes with manipulators; (2) a multi-degree of freedom fuel handling table and its clamping equipment; (3) a fuel assembly end fitting removal station and its tools; (4) a consolidator (which pulls rods, assembles the consolidated bundle and loads the canister); (5) a canister end cap welder and weld inspection system; (6) decontamination systems; and (7) the CCTV and microphone systems.

  13. Audiotactile interactions in roughness perception.

    PubMed

    Guest, Steve; Catmur, Caroline; Lloyd, Donna; Spence, Charles

    2002-09-01

    The sounds produced when we touch textured surfaces frequently provide information regarding the structure of those surfaces. It has recently been demonstrated that the perception of the texture of the hands can be modified simply by manipulating the frequency content of such touch-related sounds. We investigated whether similar auditory manipulations change people's perception of the roughness of abrasive surfaces (experiment 1). Participants were required to make speeded, forced-choice discrimination responses regarding the roughness of a series of abrasive samples which they touched briefly. Analysis of discrimination errors verified that tactile roughness perception was modulated by the frequency content of the auditory feedback. Specifically, attenuating high frequencies led to a bias towards an increased perception of tactile smoothness. In experiment 2, we replicated the rubbing-hands manipulation of previous experimenters while participants rated either the perceived roughness or wetness of their hands. The wetness scale data replicated the results in the literature, while the roughness scale data replicated the result from experiment 1. A final experiment showed that delaying the auditory feedback from the hand-rubbing reduced the magnitude of this parchment-skin illusion. These experiments demonstrate the dramatic effect that auditory frequency manipulations can have on the perceived tactile roughness and moistness of surfaces, and are consistent with the proposal that different auditory perceptual dimensions may have varying salience for different surfaces. PMID:12195518

  14. Roughness reduction on aspheric surfaces

    NASA Astrophysics Data System (ADS)

    Kiontke, S.; Kokot, Sebastian

    2015-02-01

    For a lot of applications like spectrometer and high power laser roughness as an important parameter has been discussed over and over again. Especially for high power systems the surface quality is crucial for determining the damage threshold and therefore the field of application. Above that, it has often been difficult to compare roughness measurements because of different measurement methods and the usage of filters and surface fits. Measurement results differ significantly depending on filters and especially on the measured surface size. Insights will be given how values behave depending on the quality of surface and the size of measured area. Many applications require a high quality of roughness in order to reduce scattering. Some of them in order to prevent from damage like high power laser applications. Others like spectrometers seek to increase the signal-to-noise ratio. Most of them have already been built with spherical surfaces. With higher demands on efficiency and more sophisticated versions aspherical surfaces need to be employed. Therefore, the high requirement in roughness known from spherical surfaces is also needed on aspherical surfaces. For one thing, the constant change of curvature of an aspherical surface accounts for the superior performance, for another thing, it prevents from using classical polishing technics, which guarantied this low roughness. New methods need to be qualified. In addition, also results of a new manufacturing process will be shown allowing low roughness on aspheric even with remarkable departure from the best fit sphere.

  15. Regenerative hyperpolarization in rods.

    PubMed Central

    Werblin, F S

    1975-01-01

    1. The electrical properties of the rods in Necturus maculosus were studied at the cell body and the outer segments in dark and light under current and voltage clamp with a pair of intracellular electrodes separated by about 1 mum. 2. The membrane resistance in the dark was voltage- and time-dependent both for the cell body and the outer segment. Slight depolarizations in the cell body reduced the slope resistance from 60 to 10 M omega with a time constant of about 1 sec. Polarization in either direction, at the outer segment, when greater than about 20 mV, reduced the slope resistance from 60 to 30 M omega. The dark potential in the cell body was typically -30 to -35 m V; at the outer segment it was typically only -10 to -15 mV. 3. The light-elicited voltage response in both the cell body and the outer segment was largest with the membrane near the dark potential level. In both regions, the response was reduced when the membrane was polarized in either direction. 4. Under voltage-clamp conditions, a reversal potential for the light response near + 10 mV was measured at the outer segment. At the cell body no reversal potential for the light response was measured; there the clamping current required during the light response was almost of the same magnitude at all potential levels. 5. When the membrane at the cell body was hyperpolarized in the dark under voltage clamp, a transient outward current, typically about one-half the magnitude of the initial inward clamping current was required to maintain the membrane at the clamped potential level. This outward current transient was associated with a decrease in membrane resistance with similar time course. The transient outward current reversed and became inward when the membrane was clamped to potentials more negative than -80 mV. Thus, the transient outward current appears to involve a transient activation initiated by hyperpolarization. I is regenerative in that it is initiated by hyperpolarization and tends to

  16. Status of rod consolidation, 1988

    SciTech Connect

    Bailey, W.J.

    1989-01-01

    It is estimated that the spent fuel storage pools at some domestic light-water reactors will run out of space before 2003, the year that the US Department of Energy currently predicts it will have a repository available. Of the methods being studied to alleviate the problem, rod consolidation is one of the leading candidates for achieving more efficient use of existing space in spent fuel storage pools. Rod consolidation involves mechanically removing all the fuel rods from the fuel assembly hardware (i.e., the structural components) and placing the fuel rods in a close-packed array in a canister without space grids. A typical goal of rod consolidation systems is to insert the fuel rods from two fuel assemblies into a canister that has the same exterior dimensions as one standard fuel assembly (i.e., to achieve a consolidation or compaction ratio of 2:1) and to compact the nonfuel-bearing structural components from those two fuel assemblies by a factor of 10 to 20. This report provides an overview of the current status of rod consolidation in the United States and a small amount of information on related activities in other countries. 85 refs., 36 figs., 5 tabs.

  17. Photothermal imaging through coherent infrared bundles

    NASA Astrophysics Data System (ADS)

    Milstein, Yonat; Tepper, Michal; Harrington, James A.; Ben David, Moshe; Gannot, Israel

    2011-03-01

    This study aims to develop a photothermal imaging system through a coherent infrared bundle. This system will be used to determine the oxygenation level of various tissues, suspected malignant tissues in particular. The oxygenation estimation is preformed using a computerized algorithm. In order to evaluate the system, different bundle configurations were used for the determination of the optimal one. Bundle transmittance and the algorithm's estimation ability were measured, measurements were performed using agar phantoms consisting of varying ratios of Methylene Blue and ICG. A bundle consisting of 19 Teflon waveguides with a of 1.1mm was found to be the optimal configuration with an RMS of the error of 9.38%. At a second stage the system was validated on blood samples with varying oxygenation levels and there oxygenation levels were estimated. This stage had an RMS of the error of 10.16% for the oxygenation level estimation for samples with a 50% oxygenation level and higher. Once the basic system was validated successfully on agar phantoms and blood samples a portable system was designed and built in order to fit the system for portable use. The portable system consists of a white light illuminating source followed by filters transmitting certain wavelengths, a transmitting fiber, a thermal imaging bundle and a portable thermal camera. This portable system will be evaluated in order to have an adequate portable system for implementing the method out of the lab.

  18. Prediction of incidence and surface roughness effects on turbine performance

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.

    1993-01-01

    The results of a Navier-Stokes analysis for predicting the change in turbine efficiency due to a change in either incidence or surface roughness is discussed. It was experimentally determined by Boynton, Tabibzadeh, and Hudson that polishing the SSME high pressure fuel turbine blades improved turbine efficiency by about 2 points over a wide range of operating conditions. These conditions encompassed the range of incidence seen by the turbine blading during flight. It is also necessary to be able to predict turbine performance at various operating points for future rocket turbopump applications. The code RVCQ3D, developed by Rod Chima, was used to determine the effects of changes in incidence angle on turbine blade row efficiency. The midspan Navier-Stokes results were used in conjunction with an inviscid flow analysis code to predict the efficiency of the two stage SSME over a wide range of operating conditions for smooth and rough turbine blades. The use of the Navier-Stokes analysis to predict changes in turbine efficiency due to variation in incidence angles was found to be superior to other incidence loss correlations available in the literature. The sensitivity of the Navier-Stokes results to grid parameters is discussed. The effects of the surface roughness were accounted for using the Cebeci-Chang rough wall turbulence model. This model was implemented in the code RVCQ3D. The implementation of this model for predicting the change in efficiency is also discussed.

  19. Self-sustained oscillation limit of tube bundle resonant noise. (Phase 1: Evaluation equation of oscillation limit)

    SciTech Connect

    Nishimura, M.; Fujita, K.; Hasegawa, N.

    1995-12-01

    Self-sustained oscillation limit of tube bundle resonant noise is studied in this paper. Excited acoustic energy and dissipating one in tube bundle are derived theoretically. In the exciting stage, the acoustic field is considered to be fed back to the flow field as the inlet flow fluctuation. And the acoustic damping is considered to induce the dissipating energy. Based on the energy balance of both and dimensional analysis, a new simple evaluation equation of self-sustained oscillation limit is proposed concerning on tube bundle resonant noise. A typical experimental results are evaluated based on this equation. The results are roughly good, but this suggests that model analysis of both exciting energy and dissipating one is necessary for more precise evaluation.

  20. Double bundle or single bundle plus extraarticular tenodesis in ACL reconstruction? A CAOS study.

    PubMed

    Monaco, E; Labianca, L; Conteduca, F; De Carli, A; Ferretti, A

    2007-10-01

    Anatomic reconstructions of anterior cruciate ligament (ACL) with double bundle gracilis and semitendonosus tendons graft, reproducing AM and PL bundles, have been introduced to offer a better biomechanical outcome, especially during rotatory loads. On the other hand, many methods of tenodesing the lateral aspect of the tibia to the femur to reduce internal rotation (IR) of the tibia and minimize anterior translation of the tibia relative to the femur as a backup for intra-articular reconstruction, have been also suggested. The goal of this study is to evaluate the effect, on the IR of the tibia, of a lateral reconstruction in addition to a standard single bundle ACL reconstruction as compared with an anatomic double bundle ACL reconstruction. Computer assisted ACL reconstruction has been used because it could be very effective in evaluating the global kinematic performance of the reconstructed knee. We selected 20 consecutive ACL reconstruction procedures to be performed in males in our hospital. Patients were alternately assigned to one of the two groups--group A: standard single bundle ACL reconstruction with doubled gracilis and semitendinosus tendons graft with an arthroscopically assisted two incisions technique and a lateral extraarticular reconstruction; group B: double bundle ACL reconstruction with doubled gracilis and semitendinosus tendons graft with an arthroscopically assisted two incisions technique. In all ACL reconstruction procedures navigation process was performed. Both surgical techniques reduced significantly AP displacement, IR and external rotation (ER) of the tibia respect to pre-operative ACL deficient condition (p<0.05). Comparing the group A after the single bundle reconstruction and the group B after the AM bundle fixation, non differences were found in AP displacement, IR and ER of the tibia (p=0.75, p=0.07 and p=0.07 respectively; power: 0.94). Comparing the group A after the addition of the lateral tenodesis and group B after the PL

  1. Carbon nanotube bundles under electric field perturbations

    NASA Astrophysics Data System (ADS)

    Hammes, I.; Latgé, A.

    2012-03-01

    Here we address the important role played by electric fields applied in carbon nanotube bundles in providing convenient scenarios for their use in electronic devices. We show that a gap modulation may be derived depending on the bundle configuration and the details of the applied field configuration. The system is described by a tight binding Hamiltonian and the Green function formalism is used to calculate the local density of states. Small bundles were used to validate our model on the basis of ab initio calculations. Further analysis shows that the number of tubes, geometrical configuration details and field intensities may be controlled to tune the electronic structure close to the Fermi energy, envisaging atomic-scale devices.

  2. Extremal Bundles on Calabi-Yau Threefolds

    NASA Astrophysics Data System (ADS)

    Gao, Peng; He, Yang-Hui; Yau, Shing-Tung

    2015-06-01

    We study constructions of stable holomorphic vector bundles on Calabi-Yau threefolds, especially those with exact anomaly cancellation which we call extremal. By going through the known databases we find that such examples are rare in general and can be ruled out for the spectral cover construction for all elliptic threefolds. We then introduce a general Hartshorne-Serre construction and use it to find extremal bundles of general ranks and study their stability, as well as computing their Chern numbers. Based on both existing and our new constructions, we revisit the DRY conjecture for the existence of stable sheaves on Calabi-threefolds, and provide theoretical and numerical evidence for its correctness. Our construction can be easily generalized to bundles with no extremal conditions imposed.

  3. A Kinetic Model of Active Extensile Bundles

    NASA Astrophysics Data System (ADS)

    Goldstein, Daniel; Chakraborty, Bulbul; Baskaran, Aparna

    Recent experiments in active filament networks reveal interesting rheological properties (Dan Chen: APS March Meeting 2015 D49.00001). This system consumes ATP to produce an extensile motion in bundles of microtubules. This extension then leads to self generated stresses and spontaneous flows. We propose a minimal model where the activity is modeled by self-extending bundles that are part of a cross linked network. This network can reorganize itself through buckling of extending filaments and merging events that alter the topology of the network. We numerically simulate this minimal kinetic model and examine the emergent rheological properties and determine how stresses are generated by the extensile activity. We will present results that focus on the effects of confinement and network connectivity of the bundles on stress fluctuations and response of an active gel.

  4. Porous Silicon and Denim Fiber Bundle Characterization

    NASA Astrophysics Data System (ADS)

    Deuro, Randi Ellen

    My thesis research aims to characterize and exploit materials in an efficient, rapid, non-destructive manner. Part I of this document summarizes my research on porous silicon (pSi) design, fabrication, and surface modification for use as a novel chemical sensor. The optimization of fabrication process parameters (etching time, etching solution, electrode shape, and the fixing process) on pSi photoluminescence (PL) is presented. I have also investigated the effects of analyte vapors (acetonitrile, toluene, methanol, acetone) on the pSi PL and surface chemistry using luminescence and Fourier-transform infrared (FT-IR) spectroscopy and microscopy methods. The mechanism and benefits of one method of pSi surface modification and protection (ultraviolet (UV) hydrosilylation) will also be presented. Finally, high thorough-put methods of pSi sensor production are described. In Part II of this document, I introduce a novel technique for analyzing and discriminating among denim fiber bundles. An investigation into the benefits of luminescence-based multispectral imaging (LMSI) for denim fiber bundle identification has been conducted. I explore the power of nitromethane (CH 3NO2) based quenching in fiber bundle classification and identify the quenching mechanism. The luminescence spectra (450 - 850 nm) and images from the denim fiber bundles were obtained while exciting at 325 nm or 405 nm. Here, LMSI data were recorded in < 10 s and subsequently assessed by principal component analysis (PCA) and rendered red, green, blue (RGB) component histograms. The results show that LMSI data can be used to rapidly and uniquely classify all the fiber bundle types studied in this research. These non-destructive techniques eliminate extensive sample preparation and allow for rapid multispectral image collection, analysis, and assessment. The quenching data also revealed that the dye molecules within the individual fiber bundles exhibited dramatically different accessibilities to CH 3NO2.

  5. Infrared imaging with fiber optic bundles

    NASA Astrophysics Data System (ADS)

    Hilton, Albert R., Sr.; McCord, James; Thompson, W. S.; LeBlanc, Richard A.

    2003-09-01

    Efforts have resumed to improve the image quality of infrared imaging bundles formed at AMI using the ribbon stacking method. The C4 glass has been used to reduce core size, increase packing density and improve flexibility. Ribbons are formed from unclad fiber wound on a drum with pitch, ribbon count and spacing between ribbons computer controlled. A small portion of each ribbon is compressed and fused using thin, dilute Epoxy. Unfortunately, the Epoxy, serving as a clad, absorbs most all the LWIR energy making the bundles unsuited for 8-12 μm cameras. The ribbons are removed from the drum and stacked, one on top of the other observing proper orientation to form the bundle. A typical 1 meter bundle is formed from 50-70 count ribbons for a total of 2500-4900 fibers, made from 2.5-4.9 Km of C4 fiber. Typical core diameters are 60-80 μm. Active surface area ranges from 60-70%. Infrared resolution images formed using a NIR tube camera equipped with a special relay lens demonstrates the resolution limit for the bundle. Currently, the limit is about 10 lp/mm. The bundle end is imaged in the 3-5 μm Agema 210 camera using an Amtir 1 F/1 meniscus, coated 3-5 μm. Video images taken in natural light of an individual, easily recognizable at 50 feet, will be shown. Results of careful evaluation carried out at Lockheed Martin in Orlando using a high performance Raytheon Galileo camera will be presented.

  6. Hopf solitons and elastic rods

    SciTech Connect

    Harland, Derek; Sutcliffe, Paul; Speight, Martin

    2011-03-15

    Hopf solitons in the Skyrme-Faddeev model are stringlike topological solitons classified by the integer-valued Hopf charge. In this paper we introduce an approximate description of Hopf solitons in terms of elastic rods. The general form of the elastic rod energy is derived from the field theory energy and is found to be an extension of the classical Kirchhoff rod energy. Using a minimal extension of the Kirchhoff energy, it is shown that a simple elastic rod model can reproduce many of the qualitative features of Hopf solitons in the Skyrme-Faddeev model. Features that are captured by the model include the buckling of the charge three solution, the formation of links at charges five and six, and the minimal energy trefoil knot at charge seven.

  7. Roughness effects in uncompensated antiferromagnets

    SciTech Connect

    Charilaou, M.; Hellman, F.

    2015-02-28

    Monte Carlo simulations show that roughness in uncompensated antiferromagnets decreases not just the surface magnetization but also the net magnetization and particularly strongly affects the temperature dependence. In films with step-type roughness, each step creates a new compensation front that decreases the global net magnetization. The saturation magnetization decreases non-monotonically with increasing roughness and does not scale with the surface area. Roughness in the form of surface vacancies changes the temperature-dependence of the magnetization; when only one surface has vacancies, the saturation magnetization will decrease linearly with surface occupancy, whereas when both surfaces have vacancies, the magnetization is negative and exhibits a compensation point at finite temperature, which can be tuned by controlling the occupancy. Roughness also affects the spin-texture of the surfaces due to long-range dipolar interactions and generates non-collinear spin configurations that could be used in devices to produce locally modified exchange bias. These results explain the strongly reduced magnetization found in magnetometry experiments and furthers our understanding of the temperature-dependence of exchange bias.

  8. Heat transfer to water from a vertical tube bundle under natural-circulation conditions. [PWR; BWR

    SciTech Connect

    Gruszczynski, M.J.; Viskanta, R.

    1983-01-01

    The natural circulation heat transfer data for longitudinal flow of water outside a vertical rod bundle are needed for developing correlations which can be used in best estimate computer codes to model thermal-hydraulic behavior of nuclear reactor cores under accident or shutdown conditions. The heat transfer coefficient between the fuel rod surface and the coolant is the key parameter required to predict the fuel temperature. Because of the absence of the required heat transfer coefficient data base under natural circulation conditions, experiments have been performed in a natural circulation loop. A seven-tube bundle having a pitch-to-diameter ratio of 1.25 was used as a test heat exchanger. A circulating flow was established in the loop, because of buoyancy differences between its two vertical legs. Steady-state and transient heat transfer measurements have been made over as wide a range of thermal conditions as possible with the system. Steady state heat transfer data were correlated in terms of relevant dimensionless parameters. Empirical correlations for the average Nusselt number, in terms of Reynolds number, Rayleigh number and the ratio of Grashof to Reynolds number are given.

  9. Bundling in semiflexible polymers: A theoretical overview.

    PubMed

    Benetatos, Panayotis; Jho, YongSeok

    2016-06-01

    Supramolecular assemblies of polymers are key modules to sustain the structure of cells and their function. The main elements of these assemblies are charged semiflexible polymers (polyelectrolytes) generally interacting via a long(er)-range repulsion and a short(er)-range attraction. The most common supramolecular structure formed by these polymers is the bundle. In the present paper, we critically review some recent theoretical and computational advances on the problem of bundle formation, and point a few promising directions for future work. PMID:26813628

  10. Scaling Shift in Multicracked Fiber Bundles

    NASA Astrophysics Data System (ADS)

    Manca, Fabio; Giordano, Stefano; Palla, Pier Luca; Cleri, Fabrizio

    2014-12-01

    Bundles of fibers, wires, or filaments are ubiquitous structures in both natural and artificial materials. We investigate the bundle degradation induced by an external damaging action through a theoretical model describing an assembly of parallel fibers, progressively damaged by a random population of cracks. Fibers in our model interact by means of a lateral linear coupling, thus retaining structural integrity even after substantial damage. Monte Carlo simulations of the Young's modulus degradation for increasing crack density demonstrate a remarkable scaling shift between an exponential and a power-law regime. Analytical solutions of the model confirm this behavior, and provide a thorough understanding of the underlying physics.

  11. Crosstalk analysis of carbon nanotube bundle interconnects.

    PubMed

    Zhang, Kailiang; Tian, Bo; Zhu, Xiaosong; Wang, Fang; Wei, Jun

    2012-01-01

    Carbon nanotube (CNT) has been considered as an ideal interconnect material for replacing copper for future nanoscale IC technology due to its outstanding current carrying capability, thermal conductivity, and mechanical robustness. In this paper, crosstalk problems for single-walled carbon nanotube (SWCNT) bundle interconnects are investigated; the interconnect parameters for SWCNT bundle are calculated first, and then the equivalent circuit has been developed to perform the crosstalk analysis. Based on the simulation results using SPICE simulator, the voltage of the crosstalk-induced glitch can be reduced by decreasing the line length, increasing the spacing between adjacent lines, or increasing the diameter of SWCNT. PMID:22340628

  12. Scaling shift in multicracked fiber bundles.

    PubMed

    Manca, Fabio; Giordano, Stefano; Palla, Pier Luca; Cleri, Fabrizio

    2014-12-19

    Bundles of fibers, wires, or filaments are ubiquitous structures in both natural and artificial materials. We investigate the bundle degradation induced by an external damaging action through a theoretical model describing an assembly of parallel fibers, progressively damaged by a random population of cracks. Fibers in our model interact by means of a lateral linear coupling, thus retaining structural integrity even after substantial damage. Monte Carlo simulations of the Young's modulus degradation for increasing crack density demonstrate a remarkable scaling shift between an exponential and a power-law regime. Analytical solutions of the model confirm this behavior, and provide a thorough understanding of the underlying physics. PMID:25554893

  13. Balance Ability and Proprioception after Single-Bundle, Single-Bundle Augmentation, and Double-Bundle ACL Reconstruction

    PubMed Central

    Ma, Yubao; Iwaki, Daisuke; Asaeda, Makoto; Adachi, Nobuo; Ochi, Mitsuo

    2014-01-01

    Purpose. The present study sought to determine the influences of single-bundle (SB), single-bundle augmentation (SBA), and double-bundle (DB) reconstructions on balance ability and proprioceptive function. Methods. 67 patients who underwent a single- or double-bundle ACL reconstruction or a SBA using multistranded autologous hamstring tendons were included in this study with a 1-year follow-up. Body sway and knee kinesthesia (using the threshold to detect passive motion test (TTDPM)) were measured to indicate balance ability and proprioceptive function, respectively. Additionally, within-subject differences in anterior-posterior stability of the tibia and lower extremity muscle strength were evaluated before and after surgery. Results. At 6 and 12 months after surgery, DB reconstruction resulted in better balance and proprioceptive function than SB reconstruction (P < 0.05). Although no significant difference was observed in balance ability or proprioceptive function between the SBA and DB reconstructions, knee stability was significantly better with SBA and DB reconstructions than SB reconstruction (P < 0.05). No significant differences were found in quadriceps and hamstrings strength among the three reconstruction techniques. Conclusions. Our findings consider that joint stability, proprioceptive function, and balance ability were superior with SBA and DB reconstructions compared to SB reconstruction at 6 and 12 months after surgery. PMID:25614884

  14. Recent Studies of Runway Roughness

    NASA Technical Reports Server (NTRS)

    Morris, Garland; Hall, Albert W.

    1965-01-01

    Recent studies of NASA research related to aircraft operating problems on rough runways are presented. Some of these investigations were conducted cooperatively with the airport operators, with the Federal Aviation Agency, and with the U.S. Air Force. The studies show that criteria based on power spectral levels of runway-profile data are not sufficient to define acceptable levels of runway roughness from the piloting viewpoint. Because of the large variation in response characteristics between various types of aircraft, a runway may be acceptable for some aircraft and unacceptable for others. A criterion for roughness, therefore, should be expressed in terms of aircraft response - preferably, cockpit acceleration. A criterion suggested is that the maximum vertical acceleration in the cockpit should not exceed +/- 0.4 g for sections of the runway where precise aircraft control is required.

  15. Wetting phenomena on rough substrates

    NASA Astrophysics Data System (ADS)

    Li, Hao; Kardar, Mehran

    1990-10-01

    We consider wetting phenomena in the vicinity of rough substrates. The quenched random geometry of the substrate is assumed to be a self-affine fractal with a roughness exponent of ζS. Asymptotic critical properties on approaching complete and critical wetting transitions are studied by combining the replica method with scaling and renormalization-group arguments. We find new critical behavior, controlled by a zero-temperature fixed point, when ζS exceeds the thermal roughness exponent of the emerging wetting layer. The possibility of an effective dimensional reduction due to randomness is considered. In two dimensions a number of exact results are obtained by using a many-body transfer-matrix technique.

  16. Nuclear design of Helical Cruciform Fuel rods

    SciTech Connect

    Shirvan, K.; Kazimi, M. S.

    2012-07-01

    In order to increase the power density of current and new light water reactor designs, the Helical Cruciform Fuel (HCF) rods are proposed. The HCF rods are equivalent to a cylindrical rod, with the fuel in a cruciform shaped, twisted axially. The HCF rods increase the surface area to volume ratio and inter-subchannel mixing behavior due to their cruciform and helical shapes, respectively. In a previous study, the HCF rods have shown the potential to up-rate existing PWRs by 50% and BWRs by 25%. However, HCF rods do display different neutronics modeling and performance. The cruciform cross section of HCF rods creates radially asymmetric heat generation and temperature distribution. The nominal HCF rod's beginning of life reactivity is reduced, compared to a cylindrical rod with the same fuel volume, by 500 pcm, due to increase in absorption in cladding. The rotation of these rods accounts for reactivity changes, which depends on the H/HM ratio of the pin cell. The HCF geometry shows large sensitivities to U{sup 235} or gadolinium enrichments compared to a cylindrical geometry. In addition, the gadolinium-containing HCF rods show a stronger effect on neighboring HCF rods than in case of cylindrical rods, depending on the orientation of the HCF rods. The helical geometry of the rods introduces axial shadowing of about 600 pcm, not seen in typical cylindrical rods. (authors)

  17. Development of burnup dependent fuel rod model in COBRA-TF

    NASA Astrophysics Data System (ADS)

    Yilmaz, Mine Ozdemir

    The purpose of this research was to develop a burnup dependent fuel thermal conductivity model within Pennsylvania State University, Reactor Dynamics and Fuel Management Group (RDFMG) version of the subchannel thermal-hydraulics code COBRA-TF (CTF). The model takes into account first, the degradation of fuel thermal conductivity with high burnup; and second, the fuel thermal conductivity dependence on the Gadolinium content for both UO2 and MOX fuel rods. The modified Nuclear Fuel Industries (NFI) model for UO2 fuel rods and Duriez/Modified NFI Model for MOX fuel rods were incorporated into CTF and fuel centerline predictions were compared against Halden experimental test data and FRAPCON-3.4 predictions to validate the burnup dependent fuel thermal conductivity model in CTF. Experimental test cases from Halden reactor fuel rods for UO2 fuel rods at Beginning of Life (BOL), through lifetime without Gd2O3 and through lifetime with Gd 2O3 and a MOX fuel rod were simulated with CTF. Since test fuel rod and FRAPCON-3.4 results were based on single rod measurements, CTF was run for a single fuel rod surrounded with a single channel configuration. Input decks for CTF were developed for one fuel rod located at the center of a subchannel (rod-centered subchannel approach). Fuel centerline temperatures predicted by CTF were compared against the measurements from Halden experimental test data and the predictions from FRAPCON-3.4. After implementing the new fuel thermal conductivity model in CTF and validating the model with experimental data, CTF model was applied to steady state and transient calculations. 4x4 PWR fuel bundle configuration from Purdue MOX benchmark was used to apply the new model for steady state and transient calculations. First, one of each high burnup UO2 and MOX fuel rods from 4x4 matrix were selected to carry out single fuel rod calculations and fuel centerline temperatures predicted by CTF/TORT-TD were compared against CTF /TORT-TD /FRAPTRAN

  18. NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

    DOEpatents

    Oakes, L.C.; Walker, C.S.

    1959-12-15

    ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

  19. Social Bundles: Thinking through the Infant Body

    ERIC Educational Resources Information Center

    Brownlie, Julie; Leith, Valerie M. Sheach

    2011-01-01

    Drawing on a UK research study on immunization, this article investigates parents' understandings of the relationship between themselves, their infants, other bodies, the state, and cultural practices--material and symbolic. The article argues that infant bodies are best thought of as always social bundles, rather than as biobundles made social…

  20. The Bundled Payments for Care Improvement Initiative.

    PubMed

    Hirsch, Joshua A; Leslie-Mazwi, Thabele M; Barr, Robert M; McGinty, Geraldine; Nicola, Gregory N; Silva, Ezequiel; Manchikanti, Laxmaiah

    2016-05-01

    The Affordable Care Act enters its fifth year firmly entrenched in our national consciousness. One method that has entered the vernacular for achieving cost savings is accountable care. There are other approaches that are less well known. The Bundled Payments for Care Improvement Initiative has the potential to significantly impact neurointerventionalists. We review that initiative here. PMID:25829366

  1. High precision optical fiber bundle displacement sensor

    NASA Astrophysics Data System (ADS)

    Cao, Hui-min; Chen, You-ping; Zhang, Gang; Zhou, Zu-de

    2006-02-01

    A noncontact optical fiber bundle displacement sensor with nanometer resolution and low drift is proposed. The principle of the sensor is based on reflective intensity modulation technique. The optical fiber bundle probe contains one transmitting bundle and two receiving bundles. There are 727 identical glass optical fibers with a diameter of 50μm arranged in a concentric random pattern at the probe end. The diameter of the probe coated with a thin stainless ferrule is as small as 2.5mm. A carrier amplifier system is adopted to reduce dc drift and the interference of ambient stray light. The disturbance caused by fluctuation of light source and variation of target surface reflectivity is eliminated by taking a ratio of two receiving signals. The thermal drifts from two photoelectric signal processing circuits cancel out each other by using elements with identical specifications for both photodetector-amplifier chains. The sensitivity of the sensor is 5.9mV/nm over a linear range of 700-2300μm with a nonlinearity of 1%. The achieved resolution is 1nm/square root Hz; over a dynamic bandwidth of 10KHz and the dynamic range is 286dB. It has been proved that the sensor run sufficiently well when used with nano-technological instruments.

  2. Nanowetting of rough superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Lamb, R. N.; Cookson, D. J.

    2007-12-01

    Small angle x-ray scattering has been used to investigate the in situ immersive wetting of ultrarough surfaces which exhibit superhydrophobicity with extreme water contact angle (θA=169°). Reduced scattering contrast observed from rough surfaces when partially or totally wetted reveals significant physical differences between superhydrophobic surfaces not otherwise apparent from conventional contact angle measurements.

  3. Plant Communities of Rough Rock.

    ERIC Educational Resources Information Center

    Jacobs, Linda

    A unit of study on plants grown in the Navajo community of Rough Rock, Arizona, is presented in sketches providing the common Navajo name for the plant, a literal English translation, the English name of the plant, and the Latin name. A brief description of each plant includes where the plant grows, how the Navajos use the plant, and the color and…

  4. Estimating surface roughness using stereophotogrammetry

    NASA Astrophysics Data System (ADS)

    David, V.; Krasa, J.

    2009-04-01

    At the Department of Drainage, Irrigation and Landscape Engineering (CTU Prague) we use several mathematical models for soil erosion, sediment transport and surface runoff assessment. Here we continuously struggle for successful models parameterizations. One of the typical coefficients usually taken from literature instead of measurements is surface roughness, eg. Manning roughness (Maidment, 1993). Roughness is a key to surface runoff velocity and surface runoff depth estimation but often it is very roughly estimated. Within the COST 22 Action research we focused on estimating actual surface roughness using stereophotogrammetry. Our aim was to set up a simple low cost system useful for roughness measurements in nature conditions - mainly on agricultural fields. Our system consists of Canon EOS 400 digital camera with angle viewfinder, two robust tripods and a horizontal bar with sliding 3D tripod head. We tested different camera heights and focal distances as well as various parallaxes to obtain reasonable results. Finally we shot the surfaces from 1600 millimeters with 24 and 35 mm lens and parallaxes close to 100 mm. For 3D scene development we use Geomatica 10 GIS and its OrthoEngine module. Testing the proper system and many variables of the 3D scene modelling was an important part of the first year of the project. For these purposes we first prepared a calibrated and known 3D surface consisting of 70 by 70 cm grid and several geometrical objects of different sizes and shapes. Preparing the correct lighting conditions, finding the resolving power of the system and solving the problems with low contrast areas of measured surfaces was a time consuming but interesting task. After the system calibration we started with the actual terrain measurements. Our setup, system testing and preliminary results of the roughness computations are presented on the poster. Acknowledgement This research was acomplished within national COST project OC189 „Flood risk and its

  5. Interplanetary Overlay Network Bundle Protocol Implementation

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    The Interplanetary Overlay Network (ION) system's BP package, an implementation of the Delay-Tolerant Networking (DTN) Bundle Protocol (BP) and supporting services, has been specifically designed to be suitable for use on deep-space robotic vehicles. Although the ION BP implementation is unique in its use of zero-copy objects for high performance, and in its use of resource-sensitive rate control, it is fully interoperable with other implementations of the BP specification (Internet RFC 5050). The ION BP implementation is built using the same software infrastructure that underlies the implementation of the CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol (CFDP) built into the flight software of Deep Impact. It is designed to minimize resource consumption, while maximizing operational robustness. For example, no dynamic allocation of system memory is required. Like all the other ION packages, ION's BP implementation is designed to port readily between Linux and Solaris (for easy development and for ground system operations) and VxWorks (for flight systems operations). The exact same source code is exercised in both environments. Initially included in the ION BP implementations are the following: libraries of functions used in constructing bundle forwarders and convergence-layer (CL) input and output adapters; a simple prototype bundle forwarder and associated CL adapters designed to run over an IPbased local area network; administrative tools for managing a simple DTN infrastructure built from these components; a background daemon process that silently destroys bundles whose time-to-live intervals have expired; a library of functions exposed to applications, enabling them to issue and receive data encapsulated in DTN bundles; and some simple applications that can be used for system checkout and benchmarking.

  6. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  7. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  8. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  9. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  10. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Rough diamond. 592.310 Section 592... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply...

  11. Roughness of stable, armored gravel beds

    NASA Astrophysics Data System (ADS)

    Gomez, Basil

    1993-11-01

    The grain roughness of stable armored beds that formed in a laboratory flume under a range of steady flow conditions on rounded, flat and angular gravel is analyzed. Gravel roughness geometry is determined from bed surface profiles and vertical photographs. These techniques have been employed in field situations. Thus the methodology is potentially applicable to the analysis of grain roughness in natural gravel bed channels. The description of representative roughness geometry is also analogous to that used to characterize artificial roughness arrays. Armor roughness increases with increasing flow. Armored surfaces composed of angular gravel are roughest, and surfaces formed of flat gravel offer least resistance to the flow. Stable armored beds may exhibit a tendency to maximize the ratio of the shear due to drag on representative roughness elements to total shear. Roughness concentration is strongly correlated with the energy slope, and there is a linear increase in equivalent roughness height with increasing roughness concentration. The friction factor for an armored surface varies in a linear manner with representative roughness geometry. The equation defining this relation is probably similar to that used to characterize variations in the friction factor with artificial roughness geometry at low roughness concentrations. However, to reconcile the relations for artificial and natural roughness completely, it may be necessary to explicitly consider the contribution to flow resistance made by roughness shape, background roughness, and blocking in shallow flows.

  12. An Alternative Bundle-to-Bundle Suturing Technique for Repairing Fresh Achilles Tendon Rupture.

    PubMed

    Zhao, Jingjing; Yu, Bin; Xie, Ming; Huang, Ruokun; Xiao, Kai

    2016-01-01

    The main concern about conventional Achilles tendon repair surgical techniques is how to maintain the initial strength of the ruptured Achilles tendon through complicated suturing methods. The primary surgical problem lies in the properties of the soft tissue; the deterioration of the Achilles tendon, especially in its elasticity; and the surface lubricity of the local tissues. In the present study, we describe an innovative bundle-to-bundle suturing method that addresses these potential problems. PMID:26970908

  13. Reduction of vortex induced forces and motion through surface roughness control

    SciTech Connect

    Bernitsas, Michael M; Raghavan, Kamaldev

    2014-04-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

  14. Stuck fuel rod capping sleeve

    DOEpatents

    Gorscak, Donald A.; Maringo, John J.; Nilsen, Roy J.

    1988-01-01

    A stuck fuel rod capping sleeve to be used during derodding of spent fuel assemblies if a fuel rod becomes stuck in a partially withdrawn position and, thus, has to be severed. The capping sleeve has an inner sleeve made of a lower work hardening highly ductile material (e.g., Inconel 600) and an outer sleeve made of a moderately ductile material (e.g., 304 stainless steel). The inner sleeve may be made of an epoxy filler. The capping sleeve is placed on a fuel rod which is then severed by using a bolt cutter device. Upon cutting, the capping sleeve deforms in such a manner as to prevent the gross release of radioactive fuel material

  15. Advanced gray rod control assembly

    DOEpatents

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  16. Hierarchical nanostructures self-assembled from a mixture system containing rod-coil block copolymers and rigid homopolymers.

    PubMed

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-01-01

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction εRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the εRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures. PMID:25965726

  17. Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers

    NASA Astrophysics Data System (ADS)

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-05-01

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction ɛRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the ɛRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures.

  18. Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers

    PubMed Central

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

    2015-01-01

    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction εRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the εRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures. PMID:25965726

  19. Critical heat flux in natural convection cooled TRIGA reactors with hexagonal bundle

    SciTech Connect

    Yang, J.; Avery, M.; De Angelis, M.; Anderson, M.; Corradini, M.; Feldman, E. E.; Dunn, F. E.; Matos, J. E.

    2012-07-01

    A three-rod bundle Critical Heat Flux (CHF) study at low flow, low pressure, and natural convection condition has been conducted, simulating TRIGA reactors with the hexagonally configured core. The test section is a custom-made trefoil shape tube with three identical fuel pin heater rods located symmetrically inside. The full scale fuel rod is electrically heated with a chopped-cosine axial power profile. CHF experiments were carried out with the following conditions: inlet water subcooling from 30 K to 95 K; pressure from 110 kPa to 230 kPa; mass flux up to 150 kg/m{sup 2}s. About 50 CHF data points were collected and compared with a few existing CHF correlations whose application ranges are close to the testing conditions. Some tests were performed with the forced convection to identify the potential difference between the CHF under the natural convection and forced convection. The relevance of the CHF to test parameters is investigated. (authors)

  20. All Subdomains of the Talin Rod Are Mechanically Vulnerable and May Contribute To Cellular Mechanosensing

    PubMed Central

    2016-01-01

    Although the relevance of mechanotransduction in cell signaling is currently appreciated, the mechanisms that drive this process remain largely unknown. Mechanical unfolding of proteins may trigger distinct downstream signals in cells, providing a mechanism for cellular mechanotransduction. Force-induced unfolding of talin, a prominent focal adhesion protein, has been demonstrated previously for a small portion of its rod domain. Here, using single-molecule atomic force microscopy (smAFM), we show that the entire talin rod can be unfolded by mechanical extension, over a physiological range of forces between 10 and 40 pN. We also demonstrate, through a combination of smAFM and steered molecular dynamics, that the different bundles within the talin rod exhibit a distinct hierarchy of mechanical stability. These results provide a mechanism by which different force conditions within the cell control a graduated unfolding of the talin rod. Mechanical unfolding of the rod subdomains, and the subsequent effect on talin’s binding interactions, would allow for a finely tuned cellular response to internally or externally applied forces. PMID:27380548

  1. Prediction of number of breached rods following a LBLOCA of Candu plants using a BEPU approach

    SciTech Connect

    Bang, Y. S.; Kim, K.; Seul, K. W.; Woo, S. W.; Han, B. S.

    2012-07-01

    Radioactive doses following design basis accidents (DBA) have been important safety criteria of Candu nuclear power plant and they have been predicted in terms of the number of breached fuel rods. To support the licensing review on this concern, an analysis of LBLOCA has been conducted by using the BEPU method of KINS, KINS-REM. Number of Breached Rods (NBR) following a LBLOCA was predicted at 95 percentile probabilistic upper level in 95 percentile confidence level. Peak Cladding Temperatures (PCT) of the 84 bundles in the core pass 4 were calculated from the 124 MARS code runs in which the uncertainties of 10 major parameters including fuel thermal conductivity and break flow model were implemented. The fuel rod breaching criteria, PCT>1477 K, was used to determine the NBR 95/95. From the calculation, the predicted NBR 95/95 was 1591 rods and the calculated maximum NBR was lower than 2000 rods. Through the further improvements in feedback of the channel power behavior to thermalhydraulic calculation and in channel group modeling, NBR in more reliable level can be expected. (authors)

  2. All Subdomains of the Talin Rod Are Mechanically Vulnerable and May Contribute To Cellular Mechanosensing.

    PubMed

    Haining, Alexander William M; von Essen, Magdaléna; Attwood, Simon J; Hytönen, Vesa P; Del Río Hernández, Armando

    2016-07-26

    Although the relevance of mechanotransduction in cell signaling is currently appreciated, the mechanisms that drive this process remain largely unknown. Mechanical unfolding of proteins may trigger distinct downstream signals in cells, providing a mechanism for cellular mechanotransduction. Force-induced unfolding of talin, a prominent focal adhesion protein, has been demonstrated previously for a small portion of its rod domain. Here, using single-molecule atomic force microscopy (smAFM), we show that the entire talin rod can be unfolded by mechanical extension, over a physiological range of forces between 10 and 40 pN. We also demonstrate, through a combination of smAFM and steered molecular dynamics, that the different bundles within the talin rod exhibit a distinct hierarchy of mechanical stability. These results provide a mechanism by which different force conditions within the cell control a graduated unfolding of the talin rod. Mechanical unfolding of the rod subdomains, and the subsequent effect on talin's binding interactions, would allow for a finely tuned cellular response to internally or externally applied forces. PMID:27380548

  3. Long structures in a turbulent boundary layer with a rod-roughened wall

    NASA Astrophysics Data System (ADS)

    Kim, Jung Hoon; Lee, Jae Hwa

    2015-11-01

    Direct numerical simulation (DNS) of a turbulent boundary layer (TBL) over a rod-roughened wall is performed with long streamwise domain to examine streamwise scale growth mechanism of streamwise velocity fluctuating structures. The surface roughness is the two-dimensional (2-D) rod arranged regularly in the streamwise direction. Inspection of the instantaneous flow fields and streamwise two-point spatial correlations of the streamwise velocity fluctuations shows that the streamwise and spanwise length scales of the structures over the rough wall are generally larger than those over the smooth wall, while the spanwise inclination angle to the streamwise direction (helix angle) is smaller over the rough wall. Inspection of time-evolving instantaneous fields clearly exhibits that adjacent long structures combine to form a longer structure by spanwise merging process over the rough wall, and the occurrence of the spanwise merging for the streamwise scale growth is expected to be more active over the rough wall due to turbulent scales generated by the 2-D roughness. This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2014R1A1A2057031) and 2015 Research Fund (1.150033.01) of UNIST.

  4. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    PubMed

    Kim, Young-Jin; Yamamoto, Seiichiro; Takahashi, Haruko; Sasaki, Naruo; Matsunaga, Yukiko T

    2016-08-19

    This work describes the fabrication and characterization of hydroxypropyl cellulose (HPC)-based biomimetic bundled gel fibres. The bundled gel fibres were reinforced with multiwalled carbon nanotubes (MWCNTs). A phase-separated aqueous solution with MWCNT and HPC was transformed into a bundled fibrous structure after being injected into a co-flow microfluidic device and applying the sheath flow. The resulting MWCNT-bundled gel fibres consist of multiple parallel microfibres. The mechanical and electrical properties of MWCNT-bundled gel fibres were improved and their potential for tissue engineering applications as a cell scaffold was demonstrated. PMID:27200527

  5. Anatomic Double-Bundle Posterior Cruciate Ligament Reconstruction.

    PubMed

    Chahla, Jorge; Nitri, Marco; Civitarese, David; Dean, Chase S; Moulton, Samuel G; LaPrade, Robert F

    2016-02-01

    The posterior cruciate ligament (PCL) is known to be the main posterior stabilizer of the knee. Anatomic single-bundle PCL reconstruction, focusing on reconstruction of the larger anterolateral bundle, is the most commonly performed procedure. Because of the residual posterior and rotational tibial instability after the single-bundle procedure and the inability to restore the normal knee kinematics, an anatomic double-bundle PCL reconstruction has been proposed in an effort to re-create the native PCL footprint more closely and to restore normal knee kinematics. We detail our technique for an anatomic double-bundle PCL reconstruction using Achilles and anterior tibialis tendon allografts. PMID:27284530

  6. Oxidation induced stress-rupture of fiber bundles

    SciTech Connect

    Lara-Curzio, E.

    1997-03-01

    The effect of oxidation on the stress-rupture behavior of fiber bundles was modeled. It is shown that oxidation-induced fiber strength degradation results in the delayed failure of the associated fiber bundle and that the fiber bundle strength decreases with time as t{sup {minus}1/4}. It is also shown that the temperature dependence of the bundle loss of strength reflects the thermal dependence of the mechanism controlling the oxidation of the fibers. The effect of gauge length on the fiber bundle strength was also analyzed. Numerical examples are presented for the special case of Nicalon{trademark} fibers.

  7. A two-phase flow regime map for a MAPLE-type nuclear research reactor fuel channel: Effect of hexagonal finned bundle

    SciTech Connect

    Harvel, G.D.; Chang, J.S.; Krishnan, V.S.

    1997-05-01

    A two-phase flow regime map is developed experimentally and theoretically for a vertical hexagonal flow channel with and without a 36-finned rod hexagonal bundle. This type of flow channel is of interest to MAPLE-type nuclear research reactors. The flow regime maps are determined by visual observations and observation of waveforms shown by a capacitance-type void fraction meter. The experimental results show that the inclusion of the finned hexagonal bundle shifts the flow regime transition boundaries toward higher water flow rates. Existing flow regime maps based on pipe flow require slight modifications when applied to the hexagonal flow channel with and without a MAPLE-type finned hexagonal bundle. The proposed theoretical model agrees well with experimental results.

  8. Polymer Transport Near Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Bloom, Moses; Whitmer, Jonathan; Luijten, Erik

    2011-03-01

    The rheology of dilute polymer solutions under confinement is important in biology, medicine, microfluidic device design, synthetic polymer processing, and even geologic porous media. However, the solution's specific interactions with the confining surface are poorly understood. This situation is exacerbated for composite nanoparticles, such as polymer/metallic hybrids. Using multi-particle collision dynamics, we find a rich array of transport regimes depending on small-scale surface roughness and the specific surface/solute interactions. These factors couple to hydrodynamic conditions, including flow strength and confinement geometry in unexpected ways. Our findings may be relevant to transport phenomena in certain rough-walled capillaries, such as the distribution of various nanoconjugates in vivo.

  9. Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT)

    SciTech Connect

    Burns, C. J. and Aumiler, D. L.

    2006-04-26

    The COBRA-IE computer code is a thermal-hydraulic subchannel analysis program capable of simulating phenomena present in both PWRs and BWRs. As part of ongoing COBRA-IE assessment efforts, the code has been evaluated against experimental data from the NUPEC BWR Full-Size Fine-Mesh Bundle Tests (BFBT). The BFBT experiments utilized an 8 x 8 rod bundle to simulate BWR operating conditions and power profiles, providing an excellent database for investigation of the capabilities of the code. Benchmarks performed included steady-state and transient void distribution, single-phase and two-phase pressure drop, and steady-state and transient critical power measurements. COBRA-IE effectively captured the trends seen in the experimental data with acceptable prediction error. Future sensitivity studies are planned to investigate the effects of enabling and/or modifying optional code models dealing with void drift, turbulent mixing, rewetting, and CHF.

  10. Sensing roughness and polish direction

    NASA Astrophysics Data System (ADS)

    Jakobsen, M. L.; Olesen, A. S.; Larsen, H. E.; Stubager, J.; Hanson, S. G.; Pedersen, T. F.; Pedersen, H. C.

    2016-04-01

    As a part of the work carried out on a project supported by the Danish council for technology and innovation, we have investigated the option of smoothing standard CNC machined surfaces. In the process of constructing optical prototypes, involving custom-designed optics, the development cost and time consumption can become relatively large numbers in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, but then the object needs to be manually polished. During the polishing process the operator needs information about the RMS-value of the surface roughness and the current direction of the scratches introduces by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid complications during the casting process. In this work we present a method for measuring the RMS-values of the surface roughness while simultaneously determining the polishing direction. We are mainly interested in the RMS-values in the range from 0 - 100 nm, which corresponds to the finish categories of A1, A2 and A3. Based on simple intensity measurements we estimates the RMS-value of the surface roughness, and by using a sectioned annual photo-detector to collect the scattered light we can determine the direction of polishing and distinguish light scattered from random structures and light scattered from scratches.

  11. A Comparison between Clinical Results of Selective Bundle and Double Bundle Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Yoo, Yon-Sik; Song, Si Young; Yang, Cheol Jung; Ha, Jong Mun; Kim, Yoon Sang

    2016-01-01

    Purpose The purpose of this study was to compare the clinical outcomes of arthroscopic anatomical double bundle (DB) anterior cruciate ligament (ACL) reconstruction with either selective anteromedial (AM) or posterolateral (PL) bundle reconstruction while preserving a relatively healthy ACL bundle. Materials and Methods The authors evaluated 98 patients with a mean follow-up of 30.8±4.0 months who had undergone DB or selective bundle ACL reconstructions. Of these, 34 cases underwent DB ACL reconstruction (group A), 34 underwent selective AM bundle reconstruction (group B), and 30 underwent selective PL bundle reconstructions (group C). These groups were compared with respect to Lysholm and International Knee Documentation Committee (IKDC) score, side-to-side differences of anterior laxity measured by KT-2000 arthrometer at 30 lbs, and stress radiography and Lachman and pivot shift test results. Pre- and post-operative data were objectively evaluated using a statistical approach. Results The preoperative anterior instability measured by manual stress radiography at 90° of knee flexion in group A was significantly greater than that in groups B and C (all p<0.001). At last follow-up, mean side-to-side instrumented laxities measured by the KT-2000 and manual stress radiography were significantly improved from preoperative data in all groups (all p<0.001). There were no significant differences between the three groups in anterior instability measured by KT-2000 arthrometer, pivot shift, or functional scores. Conclusion Selective bundle reconstruction in partial ACL tears offers comparable clinical results to DB reconstruction in complete ACL tears. PMID:27401652

  12. Heterotic String Compactification and New Vector Bundles

    NASA Astrophysics Data System (ADS)

    Lin, Hai; Wu, Baosen; Yau, Shing-Tung

    2016-07-01

    We propose a construction of Kähler and non-Kähler Calabi-Yau manifolds by branched double covers of twistor spaces. In this construction we use the twistor spaces of four-manifolds with self-dual conformal structures, with the examples of connected sum of n {mathbb{P}2}s. We also construct K3-fibered Calabi-Yau manifolds from the branched double covers of the blow-ups of the twistor spaces. These manifolds can be used in heterotic string compactifications to four dimensions. We also construct stable and polystable vector bundles. Some classes of these vector bundles can give rise to supersymmetric grand unified models with three generations of quarks and leptons in four dimensions.

  13. Covariance and the hierarchy of frame bundles

    NASA Technical Reports Server (NTRS)

    Estabrook, Frank B.

    1987-01-01

    This is an essay on the general concept of covariance, and its connection with the structure of the nested set of higher frame bundles over a differentiable manifold. Examples of covariant geometric objects include not only linear tensor fields, densities and forms, but affinity fields, sectors and sector forms, higher order frame fields, etc., often having nonlinear transformation rules and Lie derivatives. The intrinsic, or invariant, sets of forms that arise on frame bundles satisfy the graded Cartan-Maurer structure equations of an infinite Lie algebra. Reduction of these gives invariant structure equations for Lie pseudogroups, and for G-structures of various orders. Some new results are introduced for prolongation of structure equations, and for treatment of Riemannian geometry with higher-order moving frames. The use of invariant form equations for nonlinear field physics is implicitly advocated.

  14. Phase Slips in Oscillatory Hair Bundles

    NASA Astrophysics Data System (ADS)

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production.

  15. Are Medicare bundles in your future?

    PubMed

    Mulvany, Chad

    2015-08-01

    To ensure they are well-positioned for an expansion by the Centers for Medicare & Medicaid Services of bundled payment, hospitals that are not participants in the Bundled Payments for Care Improvement initiative should take the following steps: Understand which organizations in their markets are already participating and which might participate. Understand care utilization patterns within their care delivery networks and how those patterns affect cost per episode. Identify high-quality, cost-efficient postacute care providers and begin collaborating with them to further improve outcomes. Educate discharging physicians about the impact that choices related to postacute settings have on both beneficiary out-of-pocket obligations and overall cost of care. PMID:26548136

  16. Heterotic String Compactification and New Vector Bundles

    NASA Astrophysics Data System (ADS)

    Lin, Hai; Wu, Baosen; Yau, Shing-Tung

    2016-06-01

    We propose a construction of Kähler and non-Kähler Calabi-Yau manifolds by branched double covers of twistor spaces. In this construction we use the twistor spaces of four-manifolds with self-dual conformal structures, with the examples of connected sum of n {P2} s. We also construct K3-fibered Calabi-Yau manifolds from the branched double covers of the blow-ups of the twistor spaces. These manifolds can be used in heterotic string compactifications to four dimensions. We also construct stable and polystable vector bundles. Some classes of these vector bundles can give rise to supersymmetric grand unified models with three generations of quarks and leptons in four dimensions.

  17. Phase Slips in Oscillatory Hair Bundles

    PubMed Central

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-01-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  18. Phase slips in oscillatory hair bundles.

    PubMed

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  19. Emitters of N-photon bundles.

    PubMed

    Muñoz, C Sánchez; Del Valle, E; Tudela, A González; Müller, K; Lichtmannecker, S; Kaniber, M; Tejedor, C; Finley, J J; Laussy, F P

    2014-07-01

    Controlling the ouput of a light emitter is one of the basic tasks of photonics, with landmarks such as the laser and single-photon sources. The development of quantum applications makes it increasingly important to diversify the available quantum sources. Here, we propose a cavity QED scheme to realize emitters that release their energy in groups, or "bundles" of N photons, for integer N. Close to 100% of two-photon emission and 90% of three-photon emission is shown to be within reach of state of the art samples. The emission can be tuned with system parameters so that the device behaves as a laser or as a N-photon gun. The theoretical formalism to characterize such emitters is developed, with the bundle statistics arising as an extension of the fundamental correlation functions of quantum optics. These emitters will be useful for quantum information processing and for medical applications. PMID:25013456

  20. Radiological evidence for the triple bundle anterior cruciate ligament.

    PubMed

    MacKay, James W; Whitehead, Harry; Toms, Andoni P

    2014-10-01

    The anterior cruciate ligament (ACL) has traditionally been described as having two bundles--one anteromedial and one posterolateral. This has been challenged by studies proposing the existence of a third, intermediate, bundle with distinct functional significance, an arrangement that has been described in a number of domesticated animal species. No radiological evidence for the triple bundle ACL has previously been described. A prevalence study was carried out on 73 consecutive human knee magnetic resonance (MR) studies to determine the number of visible bundles, excluding individuals with a history of ACL injury or mucoid degeneration. A triple bundle ACL was demonstrated in 15 out of 73 human knees (20.5%, 95% confidence interval 12.9-31.2%). This is the first radiological description of the human triple bundle ACL. There was MR imaging evidence of a triple bundle ACL in approximately one fifth of human knees in this study. PMID:24890455

  1. Hierarchical scaling law for the strength of composite fibre bundles

    NASA Astrophysics Data System (ADS)

    Pimenta, Soraia; Pinho, Silvestre T.

    2013-06-01

    This paper presents an analytical model for size effects on the longitudinal tensile strength of composite fibre bundles. The strength of individual fibres is modelled by a Weibull distribution, while the matrix (or fibre-matrix interface) is represented through a perfectly plastic shear-lag model. A probabilistic analysis of the failure process in hierarchical bundles (bundles of bundles) is performed, so that a scaling law relating the strength distributions and characteristic lengths of consecutive bundle levels is derived. An efficient numerical scheme (based on asymptotic limits) is proposed, hence coupon-sized bundle strength distributions are obtained almost instantaneously. Parametric studies show that both fibre and matrix properties are critical for bundle strength; model predictions at different scales are validated against experimental results available in the literature.

  2. The effects of crushing surface roughness on the crushing characteristics of composite tubes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Wolterman, Richard L.; Kennedy, John M.

    1992-01-01

    The effects of crushing-surface roughness on the energy-absorption capability of graphite and glass-epoxy composite tubes were investigated. Fifty different combinations of fiber, matrix, and specimen ply orientation were evaluated. Two different crushing surface roughnesses were used in this investigation. Crushing surface significantly influences the energy-absorption capability only of tubes that crush in the lamina bending crushing mode; tubes that crush in other modes are not influenced because their lamina bundles do not slide against the crushing surface. Those tubes that crush in the lamina bending mode can achieve higher, lower, or no change in energy-absorption capability as crushing surface roughness increases. If the fiber failure strain of tubes that crush in the lamina bending crushing mode exceeds the matrix failure strain then the energy-absorption capability increases as crushing surface roughness increases. However, if the matrix failure strain exceeds the fiber failure strain then the energy-absorption capability increases as crushing surface roughness decreases. Energy-absorption capability is uninfluenced by crushing surface roughness for tubes that have equal fiber and matrix failure strains.

  3. Alpha1 LASSO data bundles Lamont, OK

    DOE Data Explorer

    Gustafson, William Jr; Vogelmann, Andrew; Endo, Satoshi; Toto, Tami; Xiao, Heng; Li, Zhijin; Cheng, Xiaoping; Krishna, Bhargavi (ORCID:000000018828528X)

    2016-08-03

    A data bundle is a unified package consisting of LASSO LES input and output, observations, evaluation diagnostics, and model skill scores. LES input includes model configuration information and forcing data. LES output includes profile statistics and full domain fields of cloud and environmental variables. Model evaluation data consists of LES output and ARM observations co-registered on the same grid and sampling frequency. Model performance is quantified by skill scores and diagnostics in terms of cloud and environmental variables.

  4. Uncovering Ecosystem Service Bundles through Social Preferences

    PubMed Central

    Martín-López, Berta; Iniesta-Arandia, Irene; García-Llorente, Marina; Palomo, Ignacio; Casado-Arzuaga, Izaskun; Amo, David García Del; Gómez-Baggethun, Erik; Oteros-Rozas, Elisa; Palacios-Agundez, Igone; Willaarts, Bárbara; González, José A.; Santos-Martín, Fernando; Onaindia, Miren; López-Santiago, Cesar; Montes, Carlos

    2012-01-01

    Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem’s capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem’s capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs. PMID:22720006

  5. Stable vector bundles and string theory

    SciTech Connect

    Gomez, Tomas L.; Sols, Ignacio; Lukic, Sergio

    2009-05-06

    In [4], Braun, He, Ovrut and Pantev proposed a model of string theory (based on the Calabi-Yau 3-fold X) whose low energy limit predicts certain properties of the Standard Model of particle Physics. This model depends on two vector bundles that have to be stable. We calculate the ample cone of X, and prove that one of them is stable, and the other one is not.

  6. An analytical fiber bundle model for pullout mechanics of root bundles

    NASA Astrophysics Data System (ADS)

    Cohen, D.; Schwarz, M.; Or, D.

    2011-09-01

    Roots in soil contribute to the mechanical stability of slopes. Estimation of root reinforcement is challenging because roots form complex biological networks whose geometrical and mechanical characteristics are difficult to characterize. Here we describe an analytical model that builds on simple root descriptors to estimate root reinforcement. Root bundles are modeled as bundles of heterogeneous fibers pulled along their long axes neglecting root-soil friction. Analytical expressions for the pullout force as a function of displacement are derived. The maximum pullout force and corresponding critical displacement are either derived analytically or computed numerically. Key model inputs are a root diameter distribution (uniform, Weibull, or lognormal) and three empirical power law relations describing tensile strength, elastic modulus, and length of roots as functions of root diameter. When a root bundle with root tips anchored in the soil matrix is pulled by a rigid plate, a unique parameter, ?, that depends only on the exponents of the power law relations, dictates the order in which roots of different diameters break. If ? < 1, small roots break first; if ? > 1, large roots break first. When ? = 1, all fibers break simultaneously, and the maximum tensile force is simply the roots' mean force times the number of roots in the bundle. Based on measurements of root geometry and mechanical properties, the value of ? is less than 1, usually ranging between 0 and 0.7. Thus, small roots always fail first. The model shows how geometrical and mechanical characteristics of roots and root diameter distribution affect the pullout force, its maximum and corresponding displacement. Comparing bundles of roots that have similar mean diameters, a bundle with a narrow variance in root diameter will result in a larger maximum force and a smaller displacement at maximum force than a bundle with a wide diameter distribution. Increasing the mean root diameter of a bundle without

  7. Bundled payment fails to gain a foothold In California: the experience of the IHA bundled payment demonstration.

    PubMed

    Ridgely, M Susan; de Vries, David; Bozic, Kevin J; Hussey, Peter S

    2014-08-01

    To determine whether bundled payment could be an effective payment model for California, the Integrated Healthcare Association convened a group of stakeholders (health plans, hospitals, ambulatory surgery centers, physician organizations, and vendors) to develop, through a consensus process, the methods and means of implementing bundled payment. In spite of a high level of enthusiasm and effort, the pilot did not succeed in its goal to implement bundled payment for orthopedic procedures across multiple payers and hospital-physician partners. An evaluation of the pilot documented a number of barriers, such as administrative burden, state regulatory uncertainty, and disagreements about bundle definition and assumption of risk. Ultimately, few contracts were signed, which resulted in insufficient volume to test hypotheses about the impact of bundled payment on quality and costs. Although bundled payment failed to gain a foothold in California, the evaluation provides lessons for future bundled payment initiatives. PMID:25092835

  8. Thermoreversible Gels Composed of Colloidal Silica Rods with Short-Range Attractions.

    PubMed

    Murphy, Ryan P; Hong, Kunlun; Wagner, Norman J

    2016-08-23

    Dynamic arrest transitions of colloidal suspensions containing nonspherical particles are of interest for the design and processing of various particle technologies. To better understand the effects of particle shape anisotropy and attraction strength on gel and glass formation, we present a colloidal model system of octadecyl-coated silica rods, termed as adhesive hard rods (AHR), which enables control of rod aspect ratio and temperature-dependent interactions. The aspect ratios of silica rods were controlled by varying the initial TEOS concentration following the work of Kuijk et al. (J. Am. Chem. Soc., 2011, 133, 2346-2349) and temperature-dependent attractions were introduced by coating the calcined silica rods with an octadecyl-brush and suspending in tetradecane. The rod length and aspect ratio were found to increase with TEOS concentration as expected, while other properties such as the rod diameter, coating coverage, density, and surface roughness were nearly independent of the aspect ratio. Ultrasmall angle X-ray scattering measurements revealed temperature-dependent attractions between octadecyl-coated silica rods in tetradecane, as characterized by a low-q upturn in the scattered intensity upon thermal quenching. Lastly, the rheology of a concentrated AHR suspension in tetradecane demonstrated thermoreversible gelation behavior, displaying a nearly 5 orders of magnitude change in the dynamic moduli as the temperature was cycled between 15 and 40 °C. The adhesive hard rod model system serves as a tunable platform to explore the combined influence of particle shape anisotropy and attraction strength on the dynamic arrest transitions in colloidal suspensions with thermoreversible, short-range attractions. PMID:27466883

  9. Three-Rod Linear Ion Traps

    NASA Technical Reports Server (NTRS)

    Janik, Gary R.; Prestage, John D.; Maleki, Lutfollah

    1993-01-01

    Three-parallel-rod electrode structures proposed for use in linear ion traps and possibly for electrostatic levitation of macroscopic particles. Provides wider viewing angle because they confine ions in regions outside rod-electrode structures.

  10. One-dimensional nanoferroic rods; synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Seddik, U.; Okasha, N.; Imam, N. G.

    2015-11-01

    One-dimensional nanoferroic rods of BaTiO3 were synthesized by improved citrate auto-combustion technology using tetrabutyl titanate. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize the prepared sample. The results indicated that the crystal structure of BaTiO3 is tetragonal phase with an average crystallite size of 47 nm. SEM image gives a cauliflower-like morphology of the agglomerated nanorods. The stoichiometry of the chemical composition of the BaTiO3 ceramic was confirmed by EDX. TEM micrograph exhibited that BaTiO3 nanoparticles have rod-like shape with an average length of 120 nm and width of 43 nm. AFM was used to investigate the surface topography and its roughness. The topography image in 3D showed that the BaTiO3 particles have a rod shape with an average particle size of 116 nm which in agreement with 3D TEM result.

  11. Formation of a Double Diamond Cubic Phase by Thermotropic Liquid Crystalline Self-Assembly of Bundled Bolaamphiphiles.

    PubMed

    Zeng, Xiangbing; Prehm, Marko; Ungar, Goran; Tschierske, Carsten; Liu, Feng

    2016-07-11

    A quaternary amphiphile with swallow-tail side groups displays a new bicontinuous thermotropic cubic phase with symmetry Pn3‾ m and formed by two interpenetrating networks where cylindrical segments are linked by H bonds at tetrahedral junctions. Each network segment contains two bundles, each containing 12 rod-like mesogens, lying along the segment axis. This assembly leads to the first thermotropic structure of the "double diamond" type. A quantitative geometric model is proposed to explain the occurrence of this rare phase. PMID:27270840

  12. Solid-state-laser-rod holder

    DOEpatents

    Gettemy, D.J.; Barnes, N.P.; Griggs, J.E.

    1981-08-11

    The disclosure relates to a solid state laser rod holder comprising Invar, copper tubing, and epoxy joints. Materials and coefficients of expansion of the components of the holder combine with the rod to produce a joint which will give before the rod itself will. The rod may be lased at about 70 to 80/sup 0/K and returned from such a temperature to room temperature repeatedly without its or the holder's destruction.

  13. Optical receivers using rough reflectors

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.

    1985-01-01

    This report examines the possible use of rough, or nondiffraction-limited, reflectors for collecting optical signals. It is shown that in the absence of background radiation, the reflector's surface quality has little effect on the performance of a properly designed receiver, but that the presence of even small amounts of background radiation can lead to severe performance degradation. Techniques are suggested for improving receiver performance in high-background environments, and bounds and approximations to the exact error-probability expressions are derived.

  14. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  15. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  16. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  17. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  18. Inverted Control Rod Lock-In Device

    DOEpatents

    Brussalis, W. G.; Bost, G. E.

    1962-12-01

    A mechanism which prevents control rods from dropping out of the reactor core in the event the vessel in which the reactor is mounted should capsize is described. The mechanism includes a pivoted toothed armature which engages the threaded control rod lead screw and prevents removal of the rod whenever the armature is not attracted by the provided electromagnetic means. (AEC)

  19. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  20. Fuel followed control rod installation at AFRRI

    SciTech Connect

    Moore, Mark; Owens, Chris; Forsbacka, Matt

    1992-07-01

    Fuel Followed Control Rods (FFCRs) were installed at the Armed Forces Radiobiology Research Institute's 1 MW TRIGA Reactor. The procedures for obtaining, shipping, and installing the FFCRs is described. As part of the FFCR installation, the transient rod drive was relocated. Core performance due to the addition of the fuel followed control rods is discussed. (author)

  1. Force-generation and dynamic instability of microtubule bundles

    PubMed Central

    Laan, Liedewij; Husson, Julien; Munteanu, E. Laura; Kerssemakers, Jacob W. J.; Dogterom, Marileen

    2008-01-01

    Individual dynamic microtubules can generate pushing or pulling forces when their growing or shrinking ends are in contact with cellular objects such as the cortex or chromosomes. These microtubules can operate in parallel bundles, for example when interacting with mitotic chromosomes. Here, we investigate the force-generating capabilities of a bundle of growing microtubules and study the effect that force has on the cooperative dynamics of such a bundle. We used an optical tweezers setup to study microtubule bundles growing against a microfabricated rigid barrier in vitro. We show that multiple microtubules can generate a pushing force that increases linearly with the number of microtubules present. In addition, the bundle can cooperatively switch to a shrinking state, due to a force-induced coupling of the dynamic instability of single microtubules. In the presence of GMPCPP, bundle catastrophes no longer occur, and high bundle forces are reached more effectively. We reproduce the observed behavior with a simple simulation of microtubule bundle dynamics that takes into account previously measured force effects on single microtubules. Using this simulation, we also show that a constant compressive force on a growing bundle leads to oscillations in bundle length that are of potential relevance for chromosome oscillations observed in living cells. PMID:18577596

  2. Synaptic transmission from rods to rod-dominated bipolar cells in the tiger salamander retina.

    PubMed

    Yang, X L; Wu, S M

    1993-06-11

    Synaptic transmission between photoreceptors and bipolar cells was studied in dark-adapted tiger salamander retinas. Based on the relative light sensitivity, bipolar cells, either depolarizing (DBC) or hyperpolarizing (HBC), fell into two groups: one receives inputs primarily from rods (rod-dominated bipolar cells, DBCR and HBCR) and the other receives inputs primarily from cones (cone-dominated bipolar cells, DBCC and HBCC). The input-output relations of the rod-DBCR and rod-HBCR synapses were determined by plotting the voltage responses of the rod and DBCR (or HBCR) to dim 500-nm light steps, which polarizes only the rods but not the cones. The slope gains of both synapses were the highest near the dark rod voltage (-2.5 for the rod-DBCR synapse and 4.0 for the rod-HBCR synapse), and they (the absolute values) became progressively smaller at more hyperpolarized rod voltages. PMID:8186975

  3. Diffusion-induced line-edge roughness

    NASA Astrophysics Data System (ADS)

    Stewart, Michael D.; Schmid, Gerard M.; Goldfarb, Dario L.; Angelopoulos, Marie; Willson, C. Grant

    2003-06-01

    As feature dimensions shrink, line edge roughness has become an increasing concern in semiconductor fabrication. There are numerous potential contributors to line edge roughness throughout the lithographic process and any measured roughness value on a printed device feature is, like the feature itself, a convolved function of every processing step. When the full lithographic process is used to study line edge roughness, it can be difficult to isolate the contribution to final roughness from any individual processing step or factor. To gain a more fundamental understanding of roughness generation that is specifically related to photoresist chemistry and formulation it is necessary to design experiments that separate out exposure related issues like mask dimension variation or local dose variation ("shot noise"). This can be accomplished using previously reported experimental protocols for bilayer film stack creation. The bilayer experimental approach has been used to study the effect of variations in such factors as post exposure bake time, photoacid generator loading, and developer concentration on roughness generation. Surface roughness of the developed film stacks is measured via atomic force microscopy. Surface roughness of developed bilayer film stacks may be considered analogous to sidewall roughness of printed features. An acrylate-based 193nm photoresist resin and an APEX-type resin are used in these experiments. In addition to experimental results, results from mesoscale lithographic simulations are used to gain further insight into diffusion induced roughness and how roughness in the latent image is modified during the development step.

  4. Intelligent Information Retrieval Using Rough Set Approximations.

    ERIC Educational Resources Information Center

    Srinivasan, Padmini

    1989-01-01

    Describes rough sets theory and discusses the advantages it offers for information retrieval, including the implicit inclusion of Boolean logic, term weighting, ranked retrieval output, and relevance feedback. Rough set formalism is compared to Boolean, vector, and fuzzy models of information retrieval and a small scale evaluation of rough sets is…

  5. Electrokinetic transport in microchannels with random roughness

    SciTech Connect

    Wang, Moran; Kang, Qinjun

    2008-01-01

    We present a numerical framework to model the electrokinetic transport in microchannels with random roughness. The three-dimensional microstructure of the rough channel is generated by a random generation-growth method with three statistical parameters to control the number density, the total volume fraction, and the anisotropy characteristics of roughness elements. The governing equations for the electrokinetic transport are solved by a high-efficiency lattice Poisson?Boltzmann method in complex geometries. The effects from the geometric characteristics of roughness on the electrokinetic transport in microchannels are therefore modeled and analyzed. For a given total roughness volume fraction, a higher number density leads to a lower fluctuation because of the random factors. The electroosmotic flow rate increases with the roughness number density nearly logarithmically for a given volume fraction of roughness but decreases with the volume fraction for a given roughness number density. When both the volume fraction and the number density of roughness are given, the electroosmotic flow rate is enhanced by the increase of the characteristic length along the external electric field direction but is reduced by that in the direction across the channel. For a given microstructure of the rough microchannel, the electroosmotic flow rate decreases with the Debye length. It is found that the shape resistance of roughness is responsible for the flow rate reduction in the rough channel compared to the smooth channel even for very thin double layers, and hence plays an important role in microchannel electroosmotic flows.

  6. Calibration of surface roughness standards

    NASA Astrophysics Data System (ADS)

    Thalmann, R.; Nicolet, A.; Meli, F.; Picotto, G. B.; Matus, M.; Carcedo, L.; Hemming, B.; Ganioglu, O.; De Chiffre, L.; Saraiva, F.; Bergstrand, S.; Zelenika, S.; Tonmueanwai, A.; Tsai, C.-L.; Shihua, W.; Kruger, O.; de Souza, M. M.; Salgado, J. A.; Ramotowski, Z.

    2016-01-01

    The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology organisations. Five surface texture standards of different type were circulated and on each of the standards several roughness parameters according to the standard ISO 4287 had to be determined. 32 out of 395 individual results were not consistent with the reference value. After some corrective actions the number of inconsistent results could be reduced to 20, which correspond to about 5% of the total and can statistically be expected. In addition to the material standards, two softgauges were circulated, which allow to test the software of the instruments used in the comparison. The comparison results help to support the calibraton and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Extensive wetting due to roughness

    SciTech Connect

    Yost, F.G.; Michael, J.R.; Eisenmann, E.T. . Center for Solder Science and Technology)

    1995-01-01

    Typically, a small mass of eutectic Sn-Pb solder wets a copper surface and flows radially outward to form a hemispherical shape with a contact angle of approx. 15--20 deg. When a similar mass of solder wets and thick electroless copper coated substrate, rapid radial flow commences and surprising new effects occur. Thick coats of electroless copper have a nodular surface structure and spreading on it does not subside until all solder is consumed. When the nodular structure is wetted by solder a coastline'' with many nearby islands'' are defined. Photos of regions at the wetting front were taken in the backscatter imaging mode of an SEM. These images show that solder wets the valleys between the surface nodules forming a delicate, lacy arrangement. The geometry of this coastal'' solder structure is described as fractal-like having a dimension D = 1.38 making it similar to drying fronts and cloud configurations. The importance of surface roughness in wetting phenomena is discussed in the light of an extensive history on the subject. It is shown that for spontaneous flow, assisted by roughness, the surface geometry must consist of local angles that are larger than the equilibrium contact angle. Kinetics of the wetting process are demonstrated by image analysis of wetted area taken from videotaped experiments. These experimental kinetics are shown to be similar in form to flow in open channel capillaries.

  8. a Comparison of Uav and Tls Data for Soil Roughness Assessment

    NASA Astrophysics Data System (ADS)

    Milenković, M.; Karel, W.; Ressl, C.; Pfeifer, N.

    2016-06-01

    Soil roughness represents fine-scale surface geometry which figures in many geophysical models. While static photogrammetric techniques (terrestrial images and laser scanning) have been recently proposed as a new source for deriving roughness heights, there is still need to overcome acquisition scale and viewing geometry issues. By contrast to the static techniques, images taken from unmanned aerial vehicles (UAV) can maintain near-nadir looking geometry over scales of several agricultural fields. This paper presents a pilot study on high-resolution, soil roughness reconstruction and assessment from UAV images over an agricultural plot. As a reference method, terrestrial laser scanning (TLS) was applied on a 10 m x 1.5 m subplot. The UAV images were self-calibrated and oriented within a bundle adjustment, and processed further up to a dense-matched digital surface model (DSM). The analysis of the UAV- and TLS-DSMs were performed in the spatial domain based on the surface autocorrelation function and the correlation length, and in the frequency domain based on the roughness spectrum and the surface fractal dimension (spectral slope). The TLS- and UAV-DSM differences were found to be under ±1 cm, while the UAV DSM showed a systematic pattern below this scale, which was explained by weakly tied sub-blocks of the bundle block. The results also confirmed that the existing TLS methods leads to roughness assessment up to 5 mm resolution. However, for our UAV data, this was not possible to achieve, though it was shown that for spatial scales of 12 cm and larger, both methods appear to be usable. Additionally, this paper suggests a method to propagate measurement errors to the correlation length.

  9. ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

    DOEpatents

    Young, J.N.

    1958-04-22

    An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

  10. Rod cluster having improved vane configuration

    SciTech Connect

    Shockling, L.A.; Francis, T.A.

    1989-09-05

    This patent describes a pressurized water reactor vessel, the vessel defining a predetermined axial direction of the flow of coolant therewithin and having plural spider assemblies supporting, for vertical movement within the vessel, respective clusters of rods in spaced, parallel axial relationship, parallel to the predetermined axial direction of coolant flow, and a rod guide for each spider assembly and respective cluster of rods. The rod guide having horizontally oriented support plates therewithin, each plate having an interior opening for accommodating axial movement therethrough of the spider assembly and respective cluster of rods. The opening defining plural radially extending channels and corresponding parallel interior wall surfaces of the support plate.

  11. Drag of a turbulent boundary layer with transverse 2D circular rods on the wall

    NASA Astrophysics Data System (ADS)

    Kamruzzaman, Md; Djenidi, L.; Antonia, R. A.; Talluru, K. M.

    2015-06-01

    In this paper, we present the results of a turbulent boundary layer developing over a rod-roughened wall with a spacing of ( is the spacing between two adjacent roughness elements, and is the rod diameter). Static pressure measurements are taken around a single roughness element to accurately determine the friction velocity, and the error in the origin, , which are the two prominent issues that surround rough-wall boundary layers. In addition, velocity measurements are taken at several streamwise locations using hot-wire anemometry to obtain from the momentum integral equation. Results showed that both methods give consistent values for , indicating that the contribution of the viscous drag over this rough wall is negligible. This supports the results of Perry et al. (J Fluid Mech 177:437-466, 1969) and Antonia and Luxton (J Fluid Mech 48(04):721-761, 1971) in a boundary layer and of Leonardi et al. (2003) in a channel flow but does not agree with those of Furuya et al. (J Fluids Eng 98(4):635-643, 1976). The results show that both and can be unambiguously measured on this particular rough wall. This paves the way for a proper comparison between the boundary layer developing over this wall and the smooth-wall turbulent boundary layer.

  12. A maternal effect rough deal mutation suggests that multiple pathways regulate Drosophila RZZ kinetochore recruitment

    PubMed Central

    Défachelles, Lénaïg; Hainline, Sarah G.; Menant, Alexandra; Lee, Laura A.; Karess, Roger E.

    2015-01-01

    ABSTRACT Proper kinetochore recruitment and regulation of dynein and the Mad1–Mad2 complex requires the Rod–Zw10–Zwilch (RZZ) complex. Here, we describe rodZ3, a maternal-effect Drosophila mutation changing a single residue in the Rough Deal (Rod) subunit of RZZ. Although the RZZ complex containing this altered subunit (denoted RZ3ZZ) is present in early syncytial stage embryos laid by homozygous rodZ3 mothers, it is not recruited to kinetochores. Consequently, the embryos have no spindle assembly checkpoint (SAC), and syncytial mitoses are profoundly perturbed. The polar body (residual meiotic products) cannot remain in its SAC-dependent metaphase-like state, and decondenses into chromatin. In neuroblasts of homozygous rodZ3 larvae, RZ3ZZ recruitment is only partially reduced, the SAC is functional and mitosis is relatively normal. RZ3ZZ nevertheless behaves abnormally: it does not further accumulate on kinetochores when microtubules are depolymerized; it reduces the rate of Mad1 recruitment; and it dominantly interferes with the dynein-mediated streaming of RZZ from attached kinetochores. These results suggest that the mutated residue of rodZ3 is required for normal RZZ kinetochore recruitment and function and, moreover, that the RZZ recruitment pathway might differ in syncytial stage embryos and post-embryonic somatic cells. PMID:25616898

  13. Exploiting rod technology. Final report

    SciTech Connect

    1990-06-01

    ROD development was proceeding apace until recent budgetary decisions caused funding support for ROD development to be drastically reduced. The funding which was originally provided by DARPA and the Balanced Technology Initiative (BTI) Office has been cut back to zero from $800K. To determine the aeroballistic coefficients of a candidate dart, ARDEC is currently supporting development out of its own 6.2 funds at about $100K. ARDEC has made slow progress toward achieving this end because of failures in the original dart during testing. It appears that the next dart design to be tested will diverge from the original concept visualized by DARPA and Science and Technology Associates (STA). STA, the design engineer, takes exception to these changes on the basis of inappropriate test conditions and insufficient testing. At this time, the full resolution of this issue will be difficult because of the current management structure, which separates the developer (ARDEC) from the designer (STA).

  14. Synchronization of Spontaneous Active Motility of Hair Cell Bundles

    PubMed Central

    Zhang, Tracy-Ying; Ji, Seung; Bozovic, Dolores

    2015-01-01

    Hair cells of the inner ear exhibit an active process, believed to be crucial for achieving the sensitivity of auditory and vestibular detection. One of the manifestations of the active process is the occurrence of spontaneous hair bundle oscillations in vitro. Hair bundles are coupled by overlying membranes in vivo; hence, explaining the potential role of innate bundle motility in the generation of otoacoustic emissions requires an understanding of the effects of coupling on the active bundle dynamics. We used microbeads to connect small groups of hair cell bundles, using in vitro preparations that maintain their innate oscillations. Our experiments demonstrate robust synchronization of spontaneous oscillations, with either 1:1 or multi-mode phase-locking. The frequency of synchronized oscillation was found to be near the mean of the innate frequencies of individual bundles. Coupling also led to an improved regularity of entrained oscillations, demonstrated by an increase in the quality factor. PMID:26540409

  15. Synchronization of Spontaneous Active Motility of Hair Cell Bundles.

    PubMed

    Zhang, Tracy-Ying; Ji, Seung; Bozovic, Dolores

    2015-01-01

    Hair cells of the inner ear exhibit an active process, believed to be crucial for achieving the sensitivity of auditory and vestibular detection. One of the manifestations of the active process is the occurrence of spontaneous hair bundle oscillations in vitro. Hair bundles are coupled by overlying membranes in vivo; hence, explaining the potential role of innate bundle motility in the generation of otoacoustic emissions requires an understanding of the effects of coupling on the active bundle dynamics. We used microbeads to connect small groups of hair cell bundles, using in vitro preparations that maintain their innate oscillations. Our experiments demonstrate robust synchronization of spontaneous oscillations, with either 1:1 or multi-mode phase-locking. The frequency of synchronized oscillation was found to be near the mean of the innate frequencies of individual bundles. Coupling also led to an improved regularity of entrained oscillations, demonstrated by an increase in the quality factor. PMID:26540409

  16. Mechanics of Individual Keratin Bundles in Living Cells

    PubMed Central

    Nolting, Jens-Friedrich; Möbius, Wiebke; Köster, Sarah

    2014-01-01

    Along with microtubules and microfilaments, intermediate filaments are a major component of the eukaryotic cytoskeleton and play a key role in cell mechanics. In cells, keratin intermediate filaments form networks of bundles that are sparser in structure and have lower connectivity than, for example, actin networks. Because of this, bending and buckling play an important role in these networks. Buckling events, which occur due to compressive intracellular forces and cross-talk between the keratin network and other cytoskeletal components, are measured here in situ. By applying a mechanical model for the bundled filaments, we can access the mechanical properties of both the keratin bundles themselves and the surrounding cytosol. Bundling is characterized by a coupling parameter that describes the strength of the linkage between the individual filaments within a bundle. Our findings suggest that coupling between the filaments is mostly complete, although it becomes weaker for thicker bundles, with some relative movement allowed. PMID:25468348

  17. The proteome of mouse vestibular hair bundles over development

    PubMed Central

    Krey, Jocelyn F.; Sherman, Nicholas E.; Jeffery, Erin D; Choi, Dongseok; Barr-Gillespie, Peter G.

    2015-01-01

    Development of the vertebrate hair bundle is a precisely orchestrated event that culminates in production of a tightly ordered arrangement of actin-rich stereocilia and a single axonemal kinocilium. To understand how the protein composition of the bundle changes during development, we isolated bundles from young (postnatal days P4-P6) and mature (P21-P25) mouse utricles using the twist-off method, then characterized their constituent proteins using liquid-chromatography tandem mass spectrometry with data-dependent acquisition. Using MaxQuant and label-free quantitation, we measured relative abundances of proteins in both bundles and in the whole utricle; comparison of protein abundance between the two fractions allows calculation of enrichment in bundles. These data, which are available via ProteomeXchange with identifier PXD002167, will be useful for examining the proteins present in mammalian vestibular bundles and how their concentrations change over development. PMID:26401315

  18. Historical dynamics in ecosystem service bundles.

    PubMed

    Renard, Delphine; Rhemtulla, Jeanine M; Bennett, Elena M

    2015-10-27

    Managing multiple ecosystem services (ES), including addressing trade-offs between services and preventing ecological surprises, is among the most pressing areas for sustainability research. These challenges require ES research to go beyond the currently common approach of snapshot studies limited to one or two services at a single point in time. We used a spatiotemporal approach to examine changes in nine ES and their relationships from 1971 to 2006 across 131 municipalities in a mixed-use landscape in Quebec, Canada. We show how an approach that incorporates time and space can improve our understanding of ES dynamics. We found an increase in the provision of most services through time; however, provision of ES was not uniformly enhanced at all locations. Instead, each municipality specialized in providing a bundle (set of positively correlated ES) dominated by just a few services. The trajectory of bundle formation was related to changes in agricultural policy and global trends; local biophysical and socioeconomic characteristics explained the bundles' increasing spatial clustering. Relationships between services varied through time, with some provisioning and cultural services shifting from a trade-off or no relationship in 1971 to an apparent synergistic relationship by 2006. By implementing a spatiotemporal perspective on multiple services, we provide clear evidence of the dynamic nature of ES interactions and contribute to identifying processes and drivers behind these changing relationships. Our study raises questions about using snapshots of ES provision at a single point in time to build our understanding of ES relationships in complex and dynamic social-ecological systems. PMID:26460005

  19. Systematic Bundle Adjustment of HRSC Image Data

    NASA Astrophysics Data System (ADS)

    Bostelmann, J.; Schmidt, R.; Heipke, C.

    2012-07-01

    The European Mars Express mission was launched in June 2003 and sent into orbit around Mars. On board the orbiter is the German High Resolution Stereo Camera (HRSC). This multi-line sensor images the Martian surface with a resolution of up to 12m per pixel in three dimensions and provides RGB and infra-red color information. The usage of the stereoscopic image information for the improvement of the observed position and attitude information via bundle adjustment is important to derive high quality 3D surface models, color orthoimages and other data products. In many cases overlapping image strips of different orbits can be used to form photogrammetric blocks, thus allowing the simultaneous adjustment of the exterior orientation data. This reduces not only local, but also regional inconsistencies in the data. With the growing number of HRSC image strips in this ongoing mission, the size and complexity of potential blocks is increasing. Therefore, a workflow has been built up for the systematic improvement of the exterior orientation using single orbit strips and regional blocks. For a successful bundle adjustment of blocks using multiple image strips a sufficient number of tie points in the overlapping area is needed. The number of tie points depends mainly on the geometric and radiometric quality of the images. This is considered by detailed analysis of the tie point accuracy and distribution. The combination of methods for image pre-processing, tie point matching, bundle adjustment and evaluation of the results in an automated workflow allows for all HRSC images a global assessment of the quality and a systematic selection of data for larger blocks.

  20. Tribe kills fuel rod proposal

    SciTech Connect

    1995-02-13

    This article is a review of nuclear utilities` efforts to find a repository of spent fuel rods. The rejection by the Mescalero Apaches of plans to build a waste repository on tribal lands has left a number of utilities scrambling to find interim solutions. Prairie Island will have to close before the end of the year unless a solution is found, and the Hope Creek/Salem units, exhausting there storage capacity within ten years, are considering dry-cask storage.

  1. Fuel rod assembly to manifold attachment

    DOEpatents

    Donck, Harry A.; Veca, Anthony R.; Snyder, Jr., Harold J.

    1980-01-01

    A fuel element is formed with a plurality of fuel rod assemblies detachably connected to an overhead support with each of the fuel rod assemblies having a gas tight seal with the support to allow internal fission gaseous products to flow without leakage from the fuel rod assemblies into a vent manifold passageway system on the support. The upper ends of the fuel rod assemblies are located at vertically extending openings in the support and upper threaded members are threaded to the fuel rod assemblies to connect the latter to the support. The preferred threaded members are cap nuts having a dome wall encircling an upper threaded end on the fuel rod assembly and having an upper sealing surface for sealing contact with the support. Another and lower seal is achieved by abutting a sealing surface on each fuel rod assembly with the support. A deformable portion on the cap nut locks the latter against inadvertent turning off the fuel rod assembly. Orienting means on the fuel rod and support primarily locates the fuel rods azimuthally for reception of a deforming tool for the cap nut. A cross port in the fuel rod end plug discharges into a sealed annulus within the support, which serves as a circumferential chamber, connecting the manifold gas passageways in the support.

  2. Compression of a bundle of light rays.

    PubMed

    Marcuse, D

    1971-03-01

    The performance of ray compression devices is discussed on the basis of a phase space treatment using Liouville's theorem. It is concluded that the area in phase space of the input bundle of rays is determined solely by the required compression ratio and possible limitations on the maximum ray angle at the output of the device. The efficiency of tapers and lenses as ray compressors is approximately equal. For linear tapers and lenses the input angle of the useful rays must not exceed the compression ratio. The performance of linear tapers and lenses is compared to a particular ray compressor using a graded refractive index distribution. PMID:20094478

  3. Chemical vapor infiltration of carbon fiber bundles

    SciTech Connect

    Currier, R.P.; Devlin, D.J.; Barbero, R.S.

    1992-12-31

    Chemical vapor infiltration in carbon fiber bundles is studied under isothermal conditions over the temperature range 1000--1090 C at a nominal pressure of 300 Torr. Pyrolytic decomposition of methane is used in the infiltration experiments with carbon weight gain data obtained continuously from thermogravimetric analysis. The sensitivity of the infiltration dynamics to initial yarn porosity and to spatial variations in fiber positioning are explored. Results indicate that small changes in initial porosity can have significant impact on the weight gain above the solid phase percolation threshold.

  4. Chemical vapor infiltration of carbon fiber bundles

    SciTech Connect

    Currier, R.P.; Devlin, D.J.; Barbero, R.S.

    1992-01-01

    Chemical vapor infiltration in carbon fiber bundles is studied under isothermal conditions over the temperature range 1000--1090 C at a nominal pressure of 300 Torr. Pyrolytic decomposition of methane is used in the infiltration experiments with carbon weight gain data obtained continuously from thermogravimetric analysis. The sensitivity of the infiltration dynamics to initial yarn porosity and to spatial variations in fiber positioning are explored. Results indicate that small changes in initial porosity can have significant impact on the weight gain above the solid phase percolation threshold.

  5. Bohr-Sommerfeld Lagrangians of moduli spaces of Higgs bundles

    NASA Astrophysics Data System (ADS)

    Biswas, Indranil; Gammelgaard, Niels Leth; Logares, Marina

    2015-08-01

    Let X be a compact connected Riemann surface of genus at least two. Let MH(r, d) denote the moduli space of semistable Higgs bundles on X of rank r and degree d. We prove that the compact complex Bohr-Sommerfeld Lagrangians of MH(r, d) are precisely the irreducible components of the nilpotent cone in MH(r, d) . This generalizes to Higgs G-bundles and also to the parabolic Higgs bundles.

  6. Bundle formation in parallel aligned polymers with competing interactions

    NASA Astrophysics Data System (ADS)

    Dutta, Sandipan; Benetatos, P.; Jho, Y. S.

    2016-04-01

    Aggregation of like-charged polymers is widely observed in biological- and soft-matter systems. In many systems, bundles are formed when a short-range attraction of diverse physical origin like charge bridging, hydrogen bonding or hydrophobic interaction, overcomes the longer-range charge repulsion. In this letter, we present a general mechanism of bundle formation in these systems as the breaking of the translational invariance in parallel aligned polymers with competing interactions of this type. We derive a criterion for finite-sized bundle formation as well as for macroscopic phase separation (formation of infinite bundles).

  7. Robust Mapping of Incoherent Fiber-Optic Bundles

    NASA Technical Reports Server (NTRS)

    Roberts, Harry E.; Deason, Brent E.; DePlachett, Charles P.; Pilgrim, Robert A.; Sanford, Harold S.

    2007-01-01

    A method and apparatus for mapping between the positions of fibers at opposite ends of incoherent fiber-optic bundles have been invented to enable the use of such bundles to transmit images in visible or infrared light. The method is robust in the sense that it provides useful mapping even for a bundle that contains thousands of narrow, irregularly packed fibers, some of which may be defective. In a coherent fiber-optic bundle, the input and output ends of each fiber lie at identical positions in the input and output planes; therefore, the bundle can be used to transmit images without further modification. Unfortunately, the fabrication of coherent fiber-optic bundles is too labor-intensive and expensive for many applications. An incoherent fiber-optic bundle can be fabricated more easily and at lower cost, but it produces a scrambled image because the position of the end of each fiber in the input plane is generally different from the end of the same fiber in the output plane. However, the image transmitted by an incoherent fiber-optic bundle can be unscrambled (or, from a different perspective, decoded) by digital processing of the output image if the mapping between the input and output fiber-end positions is known. Thus, the present invention enables the use of relatively inexpensive fiber-optic bundles to transmit images.

  8. Force-strain relation of bundles of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xiao, Tan; Ren, Yu; Wu, Ping; Liao, Kin

    2006-07-01

    The force-strain relation and tensile strength of carbon nanotube bundles are studied based on the assumption that the tensile strength of individual carbon nanotubes (CNTs) obeys the Weibull distribution, with nonlinear stress-strain behavior. The Weibull modulus of the CNT that characterizes the dispersion of tensile strength can be estimated in terms of the maximum sustained force and the failure strain of the bundle. Bundles of single-walled carbon nanotubes (SWNTs) were subjected to tensile testing using a nanomechanical testing device. Results show that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT bundles, more apparent at large strain.

  9. Tangent Bundle Elastica and Computer Vision.

    PubMed

    Ben-Shahar, Ohad; Ben-Yosef, Guy

    2015-01-01

    Visual curve completion, an early visual process that completes the occluded parts between observed boundary fragments (a.k.a. inducers), is a major problem in perceptual organization and a critical step toward higher level visual tasks in both biological and machine vision. Most computational contributions to solving this problem suggest desired perceptual properties that the completed contour should satisfy in the image plane, and then seek the mathematical curves that provide them. Alternatively, few studies (including by the authors) have suggested to frame the problem not in the image plane but rather in the unit tangent bundleR (2) × S(1), the space that abstracts the primary visual cortex, where curve completion allegedly occurs. Combining both schools, here we propose and develop a biologically plausible theory of elastica in the tangent bundle that provides not only perceptually superior completion results but also a rigorous computational prediction that inducer curvatures greatly affects the shape of the completed curve, as indeed indicated by human perception. PMID:26353216

  10. Development boiling to sprinkled tube bundle

    NASA Astrophysics Data System (ADS)

    Kracík, Petr; Pospíšil, Jiří

    2016-03-01

    This paper presents results of a studied heat transfer coefficient at the surface of a sprinkled tube bundle where boiling occurs. Research in the area of sprinkled exchangers can be divided into two major parts. The first part is research on heat transfer and determination of the heat transfer coefficient at sprinkled tube bundles for various liquids, whether boiling or not. The second part is testing of sprinkle modes for various tube diameters, tube pitches and tube materials and determination of individual modes' interface. All results published so far for water as the falling film liquid apply to one to three tubes for which the mentioned relations studied are determined in rigid laboratory conditions defined strictly in advance. The sprinkled tubes were not viewed from the operational perspective where there are more tubes and various modes may occur in different parts with various heat transfer values. The article focuses on these processes. The tube is located in a low-pressure chamber where vacuum is generated using an exhauster via ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another.

  11. Constrained ripple optimization of Tokamak bundle divertors

    SciTech Connect

    Hively, L.M.; Rome, J.A.; Lynch, V.E.; Lyon, J.F.; Fowler, R.H.; Peng, Y-K.M.; Dory, R.A.

    1983-02-01

    Magnetic field ripple from a tokamak bundle divertor is localized to a small toroidal sector and must be treated differently from the usual (distributed) toroidal field (TF) coil ripple. Generally, in a tokamak with an unoptimized divertor design, all of the banana-trapped fast ions are quickly lost due to banana drift diffusion or to trapping between the 1/R variation in absolute value vector B ..xi.. B and local field maxima due to the divertor. A computer code has been written to optimize automatically on-axis ripple subject to these constraints, while varying up to nine design parameters. Optimum configurations have low on-axis ripple (<0.2%) so that, now, most banana-trapped fast ions are confined. Only those ions with banana tips near the outside region (absolute value theta < or equal to 45/sup 0/) are lost. However, because finite-sized TF coils have not been used in this study, the flux bundle is not expanded.

  12. Emitters of N-photon bundles

    NASA Astrophysics Data System (ADS)

    Muñoz, C. Sánchez; Del Valle, E.; Tudela, A. González; Müller, K.; Lichtmannecker, S.; Kaniber, M.; Tejedor, C.; Finley, J. J.; Laussy, F. P.

    2014-07-01

    Controlling the output of a light emitter is one of the basic tasks in photonics, with landmarks such as the development of the laser and single-photon sources. The ever growing range of quantum applications is making it increasingly important to diversify the available quantum sources. Here, we propose a cavity quantum electrodynamics scheme to realize emitters that release their energy in groups (or `bundles') of N photons (where N is an integer). Close to 100% of two-photon emission and 90% of three-photon emission is shown to be within reach of state-of-the-art samples. The emission can be tuned with the system parameters so that the device behaves as a laser or as an N-photon gun. Here, we develop the theoretical formalism to characterize such emitters, with the bundle statistics arising as an extension of the fundamental correlation functions of quantum optics. These emitters will be useful for quantum information processing and for medical applications.

  13. Confinement-dependent friction in peptide bundles.

    PubMed

    Erbaş, Aykut; Netz, Roland R

    2013-03-19

    Friction within globular proteins or between adhering macromolecules crucially determines the kinetics of protein folding, the formation, and the relaxation of self-assembled molecular systems. One fundamental question is how these friction effects depend on the local environment and in particular on the presence of water. In this model study, we use fully atomistic MD simulations with explicit water to obtain friction forces as a single polyglycine peptide chain is pulled out of a bundle of k adhering parallel polyglycine peptide chains. The whole system is periodically replicated along the peptide axes, so a stationary state at prescribed mean sliding velocity V is achieved. The aggregation number is varied between k = 2 (two peptide chains adhering to each other with plenty of water present at the adhesion sites) and k = 7 (one peptide chain pulled out from a close-packed cylindrical array of six neighboring peptide chains with no water inside the bundle). The friction coefficient per hydrogen bond, extrapolated to the viscous limit of vanishing pulling velocity V → 0, exhibits an increase by five orders of magnitude when going from k = 2 to k = 7. This dramatic confinement-induced friction enhancement we argue to be due to a combination of water depletion and increased hydrogen-bond cooperativity. PMID:23528088

  14. Martian surface roughness and stratigraphy

    NASA Astrophysics Data System (ADS)

    Beyer, Ross Alan

    2004-12-01

    Orbital datasets can be combined and manipulated to learn about the three- dimensional structure of planetary surfaces, and the processes that have acted on them. The Mars Orbital Camera (MOC) is providing high-resolution images. These images allow qualitative inspection of features, and contain quantitative information about the shape of the surface. Using a photoclinometry technique derived from a lunar-Lambert photometric function, I am able to obtain estimates of the down-sun slope of each pixel in an image. This technique was calibrated against synthetic topography, compared to an area photoclinometry technique, and applied to the Viking and Pathfinder landing sites. It is a robust technique for obtaining the roughness and slope characteristics of large areas. It was applied to the potential landing sites for the Mars Exploration Rovers to evaluate site safety. The slopes from this point photoclinometry technique can be used to obtain a rough estimate of topography, which I used in a number of studies where topographic information was crucial. MOC images have shown that layering is pervasive on the martian surface. Mars Orbital Laser Altimeter (MOLA) data can be registered to MOC images to provide elevation constraints on layer outcrops. Such layers are observed in eastern Coprates Chasma both in the chasma rim and in a flat-topped massif. Observations indicate that the chasma stratigraphy consists of thin sequences of resistant layers and intervening thicker sequences of relatively less resistant layers. More resistant units cap the massif against erosion and result in steeper slopes than the weaker units would otherwise allow. These resistant layers can be used as stratigraphic markers which have allowed me to measure the subsidence and tilting of the massif relative to the chasma walls, providing evidence for tectonic motion in this portion of the Valles Marineris. These outcrops indicate that some of these layers may be analogus to terristrial flood

  15. High temperature control rod assembly

    DOEpatents

    Vollman, Russell E.

    1991-01-01

    A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

  16. Self-assembly of rod-coil-rod ABA-type triblock copolymers.

    PubMed

    Chen, Ji-Zhong; Sun, Zhao-Yan; Zhang, Cheng-Xiang; An, Li-Jia; Tong, Zhen

    2008-02-21

    Self-assembled behavior of symmetric ABA rod-coil-rod triblock copolymer melts is studied by applying self-consistent-field lattice techniques in three-dimensional space. The phase diagram is constructed to understand the effects of the chain architecture on the self-assembled behavior. Four stable structures are observed for the ABA rod-coil-rod triblock, i.e., spherelike, lamellar, gyroidlike, and cylindrical structures. Different from AB rod-coil diblock and BAB coil-rod-coil triblock copolymers, the lamellar structure observed in ABA rod-coil-rod triblock copolymer melts is not stable for high volume fraction of the rod component (f(rod)=0.8), which is attributed to the intramolecular interactions between the two rod blocks of the polymer chain. When 0.3rod)<0.7, the intramolecular interactions between the two rigid blocks of the polymer chain are decrease, which results in the occurrence of some interesting metastable mixed structures. These structures have not been observed in polymers containing only one rod block, such as a lamellar-alt-lamellar structure. The results are expected to provide guidance for the design of microstructures in experiments. PMID:18298171

  17. Properties of microtubule bundles induced by Glyceraldehyde-3-phosphate dehydrogenase

    NASA Astrophysics Data System (ADS)

    Somers, Marijke; Engelborghs, Yves

    1991-05-01

    The binding of Glyceraldehyde-3-phosphate dehydrogenase (GAPDH; E.C. 1.2.1.12) to microtubules causes the microtubules to assemble into large bundles. This bundling can be considered as a further step in the assembly of supramolecular structures. The rate of bundle formation, after addition of GAPDH to preformed microtubules, is not dependent on the GAPDH concentration and reflects bundling kinetics. Bundle disassembly can be studied by the addition of 1 mM adenosine 5'-(β, -imidotri-phosphate) (AMPPNP) to bundled microtubules, and is extremely fast. Bundling reduces the rate of association of tubulin dimers to microtubules, as well as the dissocation from the microtubles. Both rates are reduced to the same extent. This is in agreement with the fact that the critical concentration of tubulin is practically not influenced by the binding of the enzyme. Adding microtubule associated proteins (at I=0.1 M) does not appreciably influence the affinity for GAPDH, but reduces bundle formation possibly for sterical reasons.

  18. Hair bundle profiles along the chick basilar papilla

    PubMed Central

    DUNCAN, R. K.; ILE, K. E.; DUBIN, M. G.; SAUNDERS, J. C.

    2001-01-01

    Cochlear hair cells play a central role in the transduction of sound into neural output. Anatomical descriptions of these cells, and their protruding hair bundles, are of fundamental interest since hair cell transduction is dependent on hair bundle micromechanics and hair bundle micromechanics depends on hair bundle morphology. In this paper, we describe quantitatively changes in the staircase profile of the hair bundle along the apical portion of the chick's basilar papilla. Images of hair cells from 8 discretely dissected segments of the apical 3rd of the basilar papilla were archived, and the profile contour outlined by the tips of the stereocilia was digitised and curves were fitted by linear and power equations. The hair bundles of tall hair cells exhibited both linear and curvilinear profiles, which were equally distributed along the papilla. All short hair cells in our sample had straight contours. The differences in hair bundle shape among the tall hair cells may lead to differential susceptibility to injury and some variance in the current-displacement transduction curves due to differences in the translation of forces throughout the hair bundle. PMID:11215761

  19. Molecular Architecture of the Chick Vestibular Hair Bundle

    PubMed Central

    Shin, Jung-Bum; Krey, Jocelyn F.; Hassan, Ahmed; Metlagel, Zoltan; Tauscher, Andrew N.; Pagana, James M.; Sherman, Nicholas E.; Jeffery, Erin D.; Spinelli, Kateri J.; Zhao, Hongyu; Wilmarth, Phillip A.; Choi, Dongseok; David, Larry L.; Auer, Manfred; Barr-Gillespie, Peter G.

    2012-01-01

    Hair bundles of the inner ear have a unique structure and protein composition that underlies their sensitivity to mechanical stimulation. Using mass spectrometry, we identified and quantified >1100 proteins, present from a few to 400,000 copies per stereocilium, from purified chick bundles; 336 of these were significantly enriched in bundles. Bundle proteins that we detected have been shown to regulate cytoskeleton structure and dynamics, energy metabolism, phospholipid synthesis, and cell signaling. Three-dimensional imaging using electron tomography allowed us to count the number of actin-actin crosslinkers and actin-membrane connectors; these values compared well to those obtained from mass spectrometry. Network analysis revealed several hub proteins, including RDX (radixin) and SLC9A3R2 (NHERF2), which interact with many bundle proteins and may perform functions essential for bundle structure and function. The quantitative mass spectrometry of bundle proteins reported here establishes a framework for future characterization of dynamic processes that shape bundle structure and function. PMID:23334578

  20. Molecular architecture of the chick vestibular hair bundle.

    PubMed

    Shin, Jung-Bum; Krey, Jocelyn F; Hassan, Ahmed; Metlagel, Zoltan; Tauscher, Andrew N; Pagana, James M; Sherman, Nicholas E; Jeffery, Erin D; Spinelli, Kateri J; Zhao, Hongyu; Wilmarth, Phillip A; Choi, Dongseok; David, Larry L; Auer, Manfred; Barr-Gillespie, Peter G

    2013-03-01

    Hair bundles of the inner ear have a specialized structure and protein composition that underlies their sensitivity to mechanical stimulation. Using mass spectrometry, we identified and quantified >1,100 proteins, present from a few to 400,000 copies per stereocilium, from purified chick bundles; 336 of these were significantly enriched in bundles. Bundle proteins that we detected have been shown to regulate cytoskeleton structure and dynamics, energy metabolism, phospholipid synthesis and cell signaling. Three-dimensional imaging using electron tomography allowed us to count the number of actin-actin cross-linkers and actin-membrane connectors; these values compared well to those obtained from mass spectrometry. Network analysis revealed several hub proteins, including RDX (radixin) and SLC9A3R2 (NHERF2), which interact with many bundle proteins and may perform functions essential for bundle structure and function. The quantitative mass spectrometry of bundle proteins reported here establishes a framework for future characterization of dynamic processes that shape bundle structure and function. PMID:23334578

  1. Amplitude death of coupled hair bundles with stochastic channel noise

    NASA Astrophysics Data System (ADS)

    Kim, Kyung-Joong; Ahn, Kang-Hun

    2014-04-01

    Hair cells conduct auditory transduction in vertebrates. In lower vertebrates such as frogs and turtles, due to the active mechanism in hair cells, hair bundles (stereocilia) can be spontaneously oscillating or quiescent. Recently an amplitude death phenomenon has been proposed [K.-H. Ahn, J. R. Soc. Interface, 10, 20130525 (2013)] as a mechanism for auditory transduction in frog hair-cell bundles, where sudden cessation of the oscillations arises due to the coupling between nonidentical hair bundles. The gating of the ion channel is intrinsically stochastic due to the stochastic nature of the configuration change of the channel. The strength of the noise due to the channel gating can be comparable to the thermal Brownian noise of hair bundles. Thus, we perform stochastic simulations of the elastically coupled hair bundles. In spite of stray noisy fluctuations due to its stochastic dynamics, our simulation shows the transition from collective oscillation to amplitude death as interbundle coupling strength increases. In its stochastic dynamics, the formation of the amplitude death state of coupled hair bundles can be seen as a sudden suppression of the displacement fluctuation of the hair bundles as the coupling strength increases. The enhancement of the signal-to-noise ratio through the amplitude death phenomenon is clearly seen in the stochastic dynamics. Our numerical results demonstrate that the multiple number of transduction channels per hair bundle is an important factor to the amplitude death phenomenon, because the phenomenon may disappear for a small number of transduction channels due to strong gating noise.

  2. Bundled slaty cleavage in laminated argillite, north-central minnesota

    USGS Publications Warehouse

    Southwick, D.L.

    1987-01-01

    Exceptional bundled slaty cleavage (defined herein) has been found in drill cores of laminated, folded, weakly metamorphosed argillite at several localities in the early Proterozoic Animikie basin of north-central Minnesota. The cleavage domains are more closely spaced within the cleavage bundles than outside them, the mean tectosilicate grain size of siltstone layers, measured normal to cleavage, is less in the cleavage bundles than outside them, and the cleavage bundles are enriched in opaque phases and phyllosilicates relative to extra-bundle segments. These facts suggest that pressure solution was a major factor in bundle development. If it is assumed that opaque phases have been conserved during pressure solution, the modal differences in composition between intra-bundle and extra-bundle segments of beds provide a means for estimating bulk material shortening normal to cleavage. Argillite samples from the central part of the Animikie basin have been shortened a minimum of about 22%, as estimated by this method. These estimates are similar to the shortening values derived from other strain markers in other rock types interbedded with the argillite, and are also consistent with the regional pattern of deformation. ?? 1987.

  3. 76 FR 61365 - Bundled Payments for Care Improvement Initiative

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-04

    ... 25, 2011 we published a notice requesting applications in the Federal Register [76 FR 53137] to... HUMAN SERVICES Centers for Medicare & Medicaid Services Bundled Payments for Care Improvement Initiative.... SUMMARY: This notice extends the deadlines for the submission of the Bundled Payments for Care...

  4. Lexical Bundles: Facilitating University "Talk" in Group Discussions

    ERIC Educational Resources Information Center

    Heng, Chan Swee; Kashiha, Hadi; Tan, Helen

    2014-01-01

    Group discussion forms an integral language experience for most language learners, providing them with an opportunity to express themselves in a naturalistic setting. Multi-word expressions are commonly used and one of them is lexical bundles. Lexical bundles are types of extended collocations that occur more commonly than we expect; they are…

  5. His bundle pacing: Initial experience and lessons learned.

    PubMed

    Deshmukh, Amrish; Deshmukh, Pramod

    2016-01-01

    Direct His bundle pacing provides the most physiologic means of artificial pacing of the ventricles with a preserved His-Purkinje system and may play a role in patients with a diseased intrinsic conduction system. We describe our initial motivations and experience with permanent direct His bundle pacing and important lessons learned since that time. PMID:27591359

  6. Reactor control rod timing system. [LMFBR

    DOEpatents

    Wu, P.T.K.

    1980-03-18

    A fluid driven jet-edge whistle timing system is described for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  7. Equivalent impedance of a rough interface

    NASA Astrophysics Data System (ADS)

    Zhuk, N. P.; Tret'iakov, O. A.

    1987-10-01

    An equivalent-impedance (EI) dyad is constructed for a rough and plane (on the average) interface dividing two plane-stratified magnetodielectric media. Its characteristics are related to those of a smooth surface and to the scattering properties of the roughnesses. It is shown that the Hermitian part of an EI dyad is formed through field scattering by roughnesses into the propagating natural modes of the regular medium.

  8. Automatic safety rod for reactors. [LMFBR

    DOEpatents

    Germer, J.H.

    1982-03-23

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  9. Simplified Approach to Predicting Rough Surface Transition

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.; Stripf, M.

    2009-01-01

    Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consistent with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparisons are presented with published experimental data. Some of the data are for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach taken in this analysis is to treat the roughness in a statistical sense, consistent with what would be obtained from blades measured after exposure to actual engine environments. An approach is given to determine the equivalent sand grain roughness from the statistics of the regular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test conditions. Additional comparisons are made with experimental heat transfer data, where the roughness geometries are both regular and statistical. Using the developed analysis, heat transfer calculations are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

  10. Simplified Approach to Predicting Rough Surface Transition

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Stripf, Matthias

    2009-01-01

    Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consiste nt with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparison s are presented with published experimental data. Some of the data ar e for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach ta ken in this analysis is to treat the roughness in a statistical sense , consistent with what would be obtained from blades measured after e xposure to actual engine environments. An approach is given to determ ine the equivalent sand grain roughness from the statistics of the re gular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test co nditions. Additional comparisons are made with experimental heat tran sfer data, where the roughness geometries are both regular as well a s statistical. Using the developed analysis, heat transfer calculatio ns are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

  11. Rough set models of Physarum machines

    NASA Astrophysics Data System (ADS)

    Pancerz, Krzysztof; Schumann, Andrew

    2015-04-01

    In this paper, we consider transition system models of behaviour of Physarum machines in terms of rough set theory. A Physarum machine, a biological computing device implemented in the plasmodium of Physarum polycephalum (true slime mould), is a natural transition system. In the behaviour of Physarum machines, one can notice some ambiguity in Physarum motions that influences exact anticipation of states of machines in time. To model this ambiguity, we propose to use rough set models created over transition systems. Rough sets are an appropriate tool to deal with rough (ambiguous, imprecise) concepts in the universe of discourse.

  12. Voltage- and calcium-dependent motility of saccular hair bundles

    NASA Astrophysics Data System (ADS)

    Quiñones, Patricia M.; Meenderink, Sebastiaan W. F.; Bozovic, Dolores

    2015-12-01

    Active bundle motility, which is hypothesized to supply feedback for mechanical amplification of signals, is thought to enhance sensitivity and sharpen tuning in vestibular and auditory organs. To study active hair bundle motility, we combined high-speed camera recordings of bullfrog sacculi, which were mounted in a two-compartment chamber, and voltage-clamp of the hair cell membrane potential. Using this paradigm, we measured three types of bundle motions: 1) spontaneous oscillations which can be analyzed to measure the physiological operating range of the transduction channel; 2) a sustained quasi-static movement of the bundle that depends on membrane potential; and 3) a fast, transient and asymmetric movement that resets the bundle position and depends on changes in the membrane potential. These data support a role for both calcium and voltage in the transduction-channel function.

  13. Genetic algorithm for bundle adjustment in aerial panoramic stitching

    NASA Astrophysics Data System (ADS)

    Zhang, Chunxiao; Wen, Gaojin; Wu, Chunnan; Wang, Hongmin; Shang, Zhiming; Zhang, Qian

    2015-03-01

    This paper presents a genetic algorithm for bundle adjustment in aerial panoramic stitching. Compared with the conventional LM (Levenberg-Marquardt) algorithm for bundle adjustment, the proposed bundle adjustment combining the genetic algorithm optimization eliminates the possibility of sticking into the local minimum, and not requires the initial estimation of desired parameters, naturally avoiding the associated steps, that includes the normalization of matches, the computation of homography transformation, the calculations of rotation transformation and the focal length. Since the proposed bundle adjustment is composed of the directional vectors of matches, taking the advantages of genetic algorithm (GA), the Jacobian matrix and the normalization of residual error are not involved in the searching process. The experiment verifies that the proposed bundle adjustment based on the genetic algorithm can yield the global solution even in the unstable aerial imaging condition.

  14. Bundling of bovine and brine shrimp (Artemia) microtubules in vitro.

    PubMed

    MacRae, T H

    1984-06-01

    Cell-free extracts from embryos of the brine shrimp (Artemia) induced bundling of bovine microtubules assembled in the presence of glycerol and Mg++. Sedimentation of microtubules through sucrose cushions and subsequent electrophoresis revealed that bundling occurred independently of accessory proteins tightly bound to the microtubules. Bovine microtubules containing microtubule-associated proteins (MAPS) or assembled with taxol did not bundle. The unusual polymerization properties of homogeneous Artemia tubulin, bundling in the absence of added factors and the small number of microtubules assembled in crude embryo extracts upon addition of taxol precluded a complete comparative study of Artemia and bovine microtubule bundling. Interesting properties of the in vitro assembly of Artemia microtubules were, however, elaborated and putative Artemia MAPs were observed as a consequence of the work with brine shrimp embryos. PMID:6744423

  15. Assembly of hair bundles, an amazing problem for cell biology.

    PubMed

    Barr-Gillespie, Peter-G

    2015-08-01

    The hair bundle--the sensory organelle of inner-ear hair cells of vertebrates--exemplifies the ability of a cell to assemble complex, elegant structures. Proper construction of the bundle is required for proper mechanotransduction in response to external forces and to transmit information about sound and movement. Bundles contain tightly controlled numbers of actin-filled stereocilia, which are arranged in defined rows of precise heights. Indeed, many deafness mutations that disable hair-cell cytoskeletal proteins also disrupt bundles. Bundle assembly is a tractable problem in molecular and cellular systems biology; the sequence of structural changes in stereocilia is known, and a modest number of proteins may be involved. PMID:26229154

  16. Extendability of parallel sections in vector bundles

    NASA Astrophysics Data System (ADS)

    Kirschner, Tim

    2016-01-01

    I address the following question: Given a differentiable manifold M, what are the open subsets U of M such that, for all vector bundles E over M and all linear connections ∇ on E, any ∇-parallel section in E defined on U extends to a ∇-parallel section in E defined on M? For simply connected manifolds M (among others) I describe the entirety of all such sets U which are, in addition, the complement of a C1 submanifold, boundary allowed, of M. This delivers a partial positive answer to a problem posed by Antonio J. Di Scala and Gianni Manno (2014). Furthermore, in case M is an open submanifold of Rn, n ≥ 2, I prove that the complement of U in M, not required to be a submanifold now, can have arbitrarily large n-dimensional Lebesgue measure.

  17. Geometries and applications of active fiber bundles

    NASA Astrophysics Data System (ADS)

    Giglmayr, Josef

    2001-10-01

    Active fiber bundles (FBs) are aimed to model photonic switching and processing in 3-D without the restrictions of the photonic technology. The 2-D photonic architectures are assumed to be implemented by networks of directional couplers (DCs) and Mach-Zehnder interferometers (MZIs), respectively. For the implementation several crucial problems are expected: (1) proper operation of the spatial couplers/switches (nonblocking interconnections) and (2) coupling in the interstage interconnection section mainly caused by parallel and crossing fibers/waveguides (WGs). For the design of proper operating switches (refinement of couplers) the application of decoupling concepts of modern control theory is proposed. The final goal is to translate the refined couplers into integrated photonic architectures rather than into additional lightwave circuits (LWCs) which simply would increase the coupling. The decoupling concepts are reviewed. The paper is an attempt to prepare for applying well-known system engineering concepts to the upcoming technology of photonics.

  18. Vision, healing brush, and fiber bundles

    NASA Astrophysics Data System (ADS)

    Georgiev, Todor

    2005-03-01

    The Healing Brush is a tool introduced for the first time in Adobe Photoshop (2002) that removes defects in images by seamless cloning (gradient domain fusion). The Healing Brush algorithms are built on a new mathematical approach that uses Fibre Bundles and Connections to model the representation of images in the visual system. Our mathematical results are derived from first principles of human vision, related to adaptation transforms of von Kries type and Retinex theory. In this paper we present the new result of Healing in arbitrary color space. In addition to supporting image repair and seamless cloning, our approach also produces the exact solution to the problem of high dynamic range compression of17 and can be applied to other image processing algorithms.

  19. Emitters of N-photon bundles

    PubMed Central

    Muñoz, C. Sánchez; del Valle, E.; Tudela, A. González; Müller, K.; Lichtmannecker, S.; Kaniber, M.; Tejedor, C.; Finley, J.J.; Laussy, F.P.

    2014-01-01

    Controlling the ouput of a light emitter is one of the basic tasks of photonics, with landmarks such as the laser and single-photon sources. The development of quantum applications makes it increasingly important to diversify the available quantum sources. Here, we propose a cavity QED scheme to realize emitters that release their energy in groups, or “bundles” of N photons, for integer N. Close to 100% of two-photon emission and 90% of three-photon emission is shown to be within reach of state of the art samples. The emission can be tuned with system parameters so that the device behaves as a laser or as a N-photon gun. The theoretical formalism to characterize such emitters is developed, with the bundle statistics arising as an extension of the fundamental correlation functions of quantum optics. These emitters will be useful for quantum information processing and for medical applications. PMID:25013456

  20. Advanced tube-bundle rocket thrust chamber

    NASA Technical Reports Server (NTRS)

    Kazaroff, John M.; Pavli, Albert J.

    1990-01-01

    An advanced rocket thrust chamber for future space application is described along with an improved method of fabrication. Potential benefits of the concept are improved cyclic life, reusability, and performance. Performance improvements are anticipated because of the enhanced heat transfer into the coolant which will enable higher chamber pressure in expander cycle engines. Cyclic life, reusability and reliability improvements are anticipated because of the enhanced structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber with a tube-bundle of high conductivity copper or copper alloy tubes, and the bonding of these tubes by an electroforming operation. Further, the method of fabrication reduces chamber complexity by incorporating manifolds, jackets, and structural stiffeners while having the potential for thrust chamber cost and weight reduction.

  1. Fiber bundle model under fluid pressure.

    PubMed

    Amitrano, David; Girard, Lucas

    2016-03-01

    Internal fluid pressure often plays an important role in the rupture of brittle materials. This is a major concern for many engineering applications and for natural hazards. More specifically, the mechanisms through which fluid pressure, applied at a microscale, can enhance the failure at a macroscale and accelerate damage dynamics leading to failure remains unclear. Here we revisit the fiber bundle model by accounting for the effect of fluid under pressure that contributes to the global load supported by the fiber bundle. Fluid pressure is applied on the broken fibers, following Biot's theory. The statistical properties of damage avalanches and their evolution toward macrofailure are analyzed for a wide range of fluid pressures. The macroscopic strength of the new model appears to be strongly controlled by the action of the fluid, particularly when the fluid pressure becomes comparable with the fiber strength. The behavior remains consistent with continuous transition, i.e., second order, including for large pressure. The main change concerns the damage acceleration toward the failure that is well modeled by the concept of sweeping of an instability. When pressure is increased, the exponent β characterizing the power-law distribution avalanche sizes significantly decreases and the exponent γ characterizing the cutoff divergence when failure is approached significantly increases. This proves that fluid pressure plays a key role in failure process acting as destabilization factor. This indicates that macrofailure occurs more readily under fluid pressure, with a behavior that becomes progressively unstable as fluid pressure increases. This may have considerable consequences on our ability to forecast failure when fluid pressure is acting. PMID:27078437

  2. Fiber bundle model under fluid pressure

    NASA Astrophysics Data System (ADS)

    Amitrano, David; Girard, Lucas

    2016-03-01

    Internal fluid pressure often plays an important role in the rupture of brittle materials. This is a major concern for many engineering applications and for natural hazards. More specifically, the mechanisms through which fluid pressure, applied at a microscale, can enhance the failure at a macroscale and accelerate damage dynamics leading to failure remains unclear. Here we revisit the fiber bundle model by accounting for the effect of fluid under pressure that contributes to the global load supported by the fiber bundle. Fluid pressure is applied on the broken fibers, following Biot's theory. The statistical properties of damage avalanches and their evolution toward macrofailure are analyzed for a wide range of fluid pressures. The macroscopic strength of the new model appears to be strongly controlled by the action of the fluid, particularly when the fluid pressure becomes comparable with the fiber strength. The behavior remains consistent with continuous transition, i.e., second order, including for large pressure. The main change concerns the damage acceleration toward the failure that is well modeled by the concept of sweeping of an instability. When pressure is increased, the exponent β characterizing the power-law distribution avalanche sizes significantly decreases and the exponent γ characterizing the cutoff divergence when failure is approached significantly increases. This proves that fluid pressure plays a key role in failure process acting as destabilization factor. This indicates that macrofailure occurs more readily under fluid pressure, with a behavior that becomes progressively unstable as fluid pressure increases. This may have considerable consequences on our ability to forecast failure when fluid pressure is acting.

  3. Historical dynamics in ecosystem service bundles

    PubMed Central

    Renard, Delphine; Rhemtulla, Jeanine M.; Bennett, Elena M.

    2015-01-01

    Managing multiple ecosystem services (ES), including addressing trade-offs between services and preventing ecological surprises, is among the most pressing areas for sustainability research. These challenges require ES research to go beyond the currently common approach of snapshot studies limited to one or two services at a single point in time. We used a spatiotemporal approach to examine changes in nine ES and their relationships from 1971 to 2006 across 131 municipalities in a mixed-use landscape in Quebec, Canada. We show how an approach that incorporates time and space can improve our understanding of ES dynamics. We found an increase in the provision of most services through time; however, provision of ES was not uniformly enhanced at all locations. Instead, each municipality specialized in providing a bundle (set of positively correlated ES) dominated by just a few services. The trajectory of bundle formation was related to changes in agricultural policy and global trends; local biophysical and socioeconomic characteristics explained the bundles’ increasing spatial clustering. Relationships between services varied through time, with some provisioning and cultural services shifting from a trade-off or no relationship in 1971 to an apparent synergistic relationship by 2006. By implementing a spatiotemporal perspective on multiple services, we provide clear evidence of the dynamic nature of ES interactions and contribute to identifying processes and drivers behind these changing relationships. Our study raises questions about using snapshots of ES provision at a single point in time to build our understanding of ES relationships in complex and dynamic social-ecological systems. PMID:26460005

  4. Growth and Morphology of Rod Eutectics

    SciTech Connect

    Jing Teng; Shan Liu; R. Trivedi

    2008-03-17

    The formation of rod eutectic microstructure is investigated systematically in a succinonitrile-camphor alloy of eutectic composition by using the directional solidification technique. A new rod eutectic configuration is observed in which the rods form with elliptical cylindrical shape. Two different orientations of the ellipse are observed that differ by a 90{sup o} rotation such that the major and the minor axes are interchanged. Critical experiments in thin samples, where a single layer of rods forms, show that the spacing and orientation of the elliptic rods are governed by the growth rate and the sample thickness. In thicker samples, multi layers of rods form with circular cross-section and the scaling law between the spacing and velocity predicted by the Jackson and Hunt model is validated. A theoretical model is developed for a two-dimensional array of elliptical rods that are arranged in a hexagonal or a square array, and the results are shown to be consistent with the experimental observations. The model of elliptic rods is also shown to reduce to that for the circular rod eutectic when the lengths of the two axes are equal, and to the lamellar eutectic model when one of the axes is much larger than the other one.

  5. Temperature actuated automatic safety rod release

    DOEpatents

    Hutter, Ernest; Pardini, John A.; Walker, David E.

    1987-01-01

    A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

  6. Temperature actuated automatic safety rod release

    DOEpatents

    Hutter, E.; Pardini, J.A.; Walker, D.E.

    1984-03-13

    A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

  7. The directional sensitivity of retinal rods.

    PubMed Central

    Alpern, M; Ching, C C; Kitahara, K

    1983-01-01

    Rod field sensitivity, 10-S(r) (i.e. the reciprocal of the radiance of a background required for 10-fold elevation of rod threshold) was measured for monochromatic backgrounds traversing the pupil at various points (r) on three subjects. The wave-length dependency of the directional sensitivities of the three foveal cone mechanisms of the principal subject have been reported previously (Alpern & Kitahara, 1983). Rods, as cones, are less sensitive to obliquely incident, than to normally incident backgrounds. At the pupil margin (4 mm) the effect is between 0.368 and 0.976 log10 units smaller for rods. After correction for losses by corneal reflexion and by absorption in the lens, S(r) for rods is reasonably described by the parabolic equation used by Stiles (1937) to quantify the directional sensitivity of cones. The small effect for rods precludes a description as consistently precise as this equation provides for cones. The steepness of the parabolic curve best fitting the directional sensitivity data of the rods of the principal subject was independent of background wave number. For a second subject, whose rods are supposed to be smaller, it was directly proportional to the square of that wave number. The latter is the expectation if the directional sensitivity of this subject's rods were determined by principles outlined in the diffraction theory of Simon (1970). PMID:6644624

  8. Experimental investigations of uncovered-bundle heat transfer and two-phase mixture-level swell under high-pressure low heat-flux conditions. [PWR

    SciTech Connect

    Anklam, T. M.; Miller, R. J.; White, M. D.

    1982-03-01

    Results are reported from a series of uncovered-bundle heat transfer and mixture-level swell tests. Experimental testing was performed at Oak Ridge National Laboratory in the Thermal Hydraulic Test Facility (THTF). The THTF is an electrically heated bundle test loop configured to produce conditions similar to those in a small-break loss-of-coolant accident. The objective of heat transfer testing was to acquire heat transfer coefficients and fluid conditions in a partially uncovered bundle. Testing was performed in a quasi-steady-state mode with the heated core 30 to 40% uncovered. Linear heat rates varied from 0.32 to 2.22 kW/m.rod (0.1 to 0.68 kW/ft.rod). Under these conditions peak clad temperatures in excess of 1050 K (1430/sup 0/F) were observed, and total heat transfer coefficients ranged from 0.0045 to 0.037 W/cm/sup 2/.K (8 to 65 Btu/h.ft/sup 2/./sup 0/F). Spacer grids were observed to enhance heat transfer at, and downstream of, the grid. Radiation heat transfer was calculated to account for as much as 65% of total heat transfer in low-flow tests.

  9. His bundle recordings in right bundle-branch block coexisting with iatrogenic right ventricular pre-excitation

    PubMed Central

    Castellanos, Agustin; Castillo, Cesar A.

    1972-01-01

    Iatrogenic right ventricular pre-excitation failed to abolish right bundle-branch block in two patients. When `exclusive' His bundle pacing was performed, the QRS complexes, St-V, and St-LVE intervals were similar to the ventricular deflections, H-V, and V-LVE (intervals) recorded during sinus rhythm. `Exclusive' pacing of the ordinary muscle at the right ventricular inflow tract produced a complete left bundle-branch block pattern without abnormal left axis deviation. Pacing of both His bundle and ordinary muscle yielded combination complexes in which the right bundle-branch block pattern persisted. The ventricular activation process was studied in these beats, as well as during the right and left bundle-branch block induced by coupled atrial stimulation. It appeared as if certain areas of the right septal surface behaved, electrophysiologically, as if they belonged to the left ventricle. Impulses emerging from these sites were not propagated to the right ventricular free wall. The latter was activated by the excitation front emerging through the left bundle system. During right bundle-branch block the endocardium of the right ventricular inflow was activated before the peak of the R in V1. Bipolar leads, 1 mm apart (with the possible exception of the ones over the tricuspid valve), were helpful in mapping the spread of activation in the human heart. Images PMID:18610233

  10. Zwilch, a New Component of the ZW10/ROD Complex Required for Kinetochore Functions

    PubMed Central

    Williams, Byron C.; Li, ZeXiao; Liu, Songtao; Williams, Erika V.; Leung, Garmay; Yen, Tim J.; Goldberg, Michael L.

    2003-01-01

    The Zeste-White 10 (ZW10) and Rough Deal (ROD) proteins are part of a complex necessary for accurate chromosome segregation. This complex recruits cytoplasmic dynein to the kinetochore and participates in the spindle checkpoint. We used immunoaffinity chromatography and mass spectroscopy to identify the Drosophila proteins in this complex. We found that the complex contains an additional protein we name Zwilch. Zwilch localizes to kinetochores and kinetochore microtubules in a manner identical to ZW10 and ROD. We have also isolated a zwilch mutant, which exhibits the same mitotic phenotypes associated with zw10 and rod mutations: lagging chromosomes at anaphase and precocious sister chromatid separation upon activation of the spindle checkpoint. Zwilch's role within the context of this complex is evolutionarily conserved. The human Zwilch protein (hZwilch) coimmunoprecipitates with hZW10 and hROD from HeLa cell extracts and localizes to the kinetochores at prometaphase. Finally, we discuss immunoaffinity chromatography results that suggest the existence of a weak interaction between the ZW10/ROD/Zwilch complex and the kinesin-like kinetochore component CENP-meta. PMID:12686595

  11. Connexin 36 and rod bipolar cell independent rod pathways drive retinal ganglion cells and optokinetic reflexes.

    PubMed

    Cowan, Cameron S; Abd-El-Barr, Muhammad; van der Heijden, Meike; Lo, Eric M; Paul, David; Bramblett, Debra E; Lem, Janis; Simons, David L; Wu, Samuel M

    2016-02-01

    Rod pathways are a parallel set of synaptic connections which enable night vision by relaying and processing rod photoreceptor light responses. We use dim light stimuli to isolate rod pathway contributions to downstream light responses then characterize these contributions in knockout mice lacking rod transducin-α (Trα), or certain pathway components associated with subsets of rod pathways. These comparisons reveal that rod pathway driven light sensitivity in retinal ganglion cells (RGCs) is entirely dependent on Trα, but partially independent of connexin 36 (Cx36) and rod bipolar cells. Pharmacological experiments show that rod pathway-driven and Cx36-independent RGC ON responses are also metabotropic glutamate receptor 6-dependent. To validate the RGC findings in awake, behaving animals we measured optokinetic reflexes (OKRs), which are sensitive to changes in ON pathways. Scotopic OKR contrast sensitivity was lost in Trα(-/-) mice, but indistinguishable from controls in Cx36(-/-) and rod bipolar cell knockout mice. Mesopic OKRs were also altered in mutant mice: Trα(-/-) mice had decreased spatial acuity, rod BC knockouts had decreased sensitivity, and Cx36(-/-) mice had increased sensitivity. These results provide compelling evidence against the complete Cx36 or rod BC dependence of night vision's ON component. Further, the findings suggest the parallel nature of rod pathways provides considerable redundancy to scotopic light sensitivity but distinct contributions to mesopic responses through complicated interactions with cone pathways. PMID:26718442

  12. Mesoscale simulation of semiflexible chains. II. Evolution dynamics and stability of fiber bundle networks.

    PubMed

    Groot, Robert D

    2013-06-14

    Network formation of associative semiflexible fibers and mixtures of fibers and colloidal particles is simulated for the Johnson-Kendall-Roberts model of elastic contacts, and a phase diagram in terms of particle elasticity and surface energy is presented. When fibers self-assemble, they form a network for sufficiently large fiber-solvent surface energy. If the surface energy is above the value where single particles crystallize, the adhesion forces drive diffusion-limited aggregation. Two mechanisms contribute to coarsening: non-associated chains joining existing bundles, and fiber bundles merging. Coarsening stops when the length of the network connections is roughly the persistence length, independent of surface energy. If the surface energy is below the value where single particles crystallize, a network can still be formed but at a much slower (reaction limited) rate. Loose (liquid-like) assemblies between chains form when they happen to run more-or-less parallel. These assemblies grow by diffusion and aggregation and form a loose network, which sets in micro-phase separation, i.e., syneresis. Only when the clusters crystallize, the coarsening process stops. In this case, the length of the network connections is larger than the persistence length of a single chain, and depends on the value of the surface energy. All networks of semiflexible homopolymers in this study show syneresis. Mixtures of fibers and colloid particles also form fiber bundle networks, but by choosing the colloid volume fraction sufficiently low, swelling gels are obtained. Applications of this model are in biological systems where fibers self-assemble into cell walls and bone tissue. PMID:23781818

  13. Mesoscale simulation of semiflexible chains. II. Evolution dynamics and stability of fiber bundle networks

    NASA Astrophysics Data System (ADS)

    Groot, Robert D.

    2013-06-01

    Network formation of associative semiflexible fibers and mixtures of fibers and colloidal particles is simulated for the Johnson-Kendall-Roberts model of elastic contacts, and a phase diagram in terms of particle elasticity and surface energy is presented. When fibers self-assemble, they form a network for sufficiently large fiber-solvent surface energy. If the surface energy is above the value where single particles crystallize, the adhesion forces drive diffusion-limited aggregation. Two mechanisms contribute to coarsening: non-associated chains joining existing bundles, and fiber bundles merging. Coarsening stops when the length of the network connections is roughly the persistence length, independent of surface energy. If the surface energy is below the value where single particles crystallize, a network can still be formed but at a much slower (reaction limited) rate. Loose (liquid-like) assemblies between chains form when they happen to run more-or-less parallel. These assemblies grow by diffusion and aggregation and form a loose network, which sets in micro-phase separation, i.e., syneresis. Only when the clusters crystallize, the coarsening process stops. In this case, the length of the network connections is larger than the persistence length of a single chain, and depends on the value of the surface energy. All networks of semiflexible homopolymers in this study show syneresis. Mixtures of fibers and colloid particles also form fiber bundle networks, but by choosing the colloid volume fraction sufficiently low, swelling gels are obtained. Applications of this model are in biological systems where fibers self-assemble into cell walls and bone tissue.

  14. Wetting properties of molecularly rough surfaces

    SciTech Connect

    Svoboda, Martin; Lísal, Martin; Malijevský, Alexandr

    2015-09-14

    We employ molecular dynamics simulations to study the wettability of nanoscale rough surfaces in systems governed by Lennard-Jones (LJ) interactions. We consider both smooth and molecularly rough planar surfaces. Solid substrates are modeled as a static collection of LJ particles arranged in a face-centered cubic lattice with the (100) surface exposed to the LJ fluid. Molecularly rough solid surfaces are prepared by removing several strips of LJ atoms from the external layers of the substrate, i.e., forming parallel nanogrooves on the surface. We vary the solid-fluid interactions to investigate strongly and weakly wettable surfaces. We determine the wetting properties by measuring the equilibrium droplet profiles that are in turn used to evaluate the contact angles. Macroscopic arguments, such as those leading to Wenzel’s law, suggest that surface roughness always amplifies the wetting properties of a lyophilic surface. However, our results indicate the opposite effect from roughness for microscopically corrugated surfaces, i.e., surface roughness deteriorates the substrate wettability. Adding the roughness to a strongly wettable surface shrinks the surface area wet with the liquid, and it either increases or only marginally affects the contact angle, depending on the degree of liquid adsorption into the nanogrooves. For a weakly wettable surface, the roughness changes the surface character from lyophilic to lyophobic due to a weakening of the solid-fluid interactions by the presence of the nanogrooves and the weaker adsorption of the liquid into the nanogrooves.

  15. Optical methods for cylindrical rough surface testing

    NASA Astrophysics Data System (ADS)

    Perez Quintian, F.; Rebollo, Maria A.; Gaggioli, Nestor G.; Raffo, C. A.

    1999-07-01

    This work studies theoretically the scattering of light from cylindrical rough surfaces. It is shown, for the conical diffraction configuration, that the mean intensity on an observation plane perpendicular to the cylinder longitudinal axis, is related to the statistical parameters that characterize the surface: the roughness (sigma) and the correlation length T.

  16. Roughness configuration matters for aeolian sediment flux

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of s...

  17. Wetting properties of molecularly rough surfaces.

    PubMed

    Svoboda, Martin; Malijevský, Alexandr; Lísal, Martin

    2015-09-14

    We employ molecular dynamics simulations to study the wettability of nanoscale rough surfaces in systems governed by Lennard-Jones (LJ) interactions. We consider both smooth and molecularly rough planar surfaces. Solid substrates are modeled as a static collection of LJ particles arranged in a face-centered cubic lattice with the (100) surface exposed to the LJ fluid. Molecularly rough solid surfaces are prepared by removing several strips of LJ atoms from the external layers of the substrate, i.e., forming parallel nanogrooves on the surface. We vary the solid-fluid interactions to investigate strongly and weakly wettable surfaces. We determine the wetting properties by measuring the equilibrium droplet profiles that are in turn used to evaluate the contact angles. Macroscopic arguments, such as those leading to Wenzel's law, suggest that surface roughness always amplifies the wetting properties of a lyophilic surface. However, our results indicate the opposite effect from roughness for microscopically corrugated surfaces, i.e., surface roughness deteriorates the substrate wettability. Adding the roughness to a strongly wettable surface shrinks the surface area wet with the liquid, and it either increases or only marginally affects the contact angle, depending on the degree of liquid adsorption into the nanogrooves. For a weakly wettable surface, the roughness changes the surface character from lyophilic to lyophobic due to a weakening of the solid-fluid interactions by the presence of the nanogrooves and the weaker adsorption of the liquid into the nanogrooves. PMID:26374050

  18. Computational Methods for Rough Classification and Discovery.

    ERIC Educational Resources Information Center

    Bell, D. A.; Guan, J. W.

    1998-01-01

    Rough set theory is a new mathematical tool to deal with vagueness and uncertainty. Computational methods are presented for using rough sets to identify classes in datasets, finding dependencies in relations, and discovering rules which are hidden in databases. The methods are illustrated with a running example from a database of car test results.…

  19. Structure of the 34 kDa F-actin-bundling protein ABP34 from Dictyostelium discoideum.

    PubMed

    Kim, Min-Kyu; Kim, Ji-Hye; Kim, Ji-Sun; Kang, Sa-Ouk

    2015-09-01

    The crystal structure of the 34 kDa F-actin-bundling protein ABP34 from Dictyostelium discoideum was solved by Ca(2+)/S-SAD phasing and refined at 1.89 Å resolution. ABP34 is a calcium-regulated actin-binding protein that cross-links actin filaments into bundles. Its in vitro F-actin-binding and F-actin-bundling activities were confirmed by a co-sedimentation assay and transmission electron microscopy. The co-localization of ABP34 with actin in cells was also verified. ABP34 adopts a two-domain structure with an EF-hand-containing N-domain and an actin-binding C-domain, but has no reported overall structural homologues. The EF-hand is occupied by a calcium ion with a pentagonal bipyramidal coordination as in the canonical EF-hand. The C-domain structure resembles a three-helical bundle and superposes well onto the rod-shaped helical structures of some cytoskeletal proteins. Residues 216-244 in the C-domain form part of the strongest actin-binding sites (193-254) and exhibit a conserved sequence with the actin-binding region of α-actinin and ABP120. Furthermore, the second helical region of the C-domain is kinked by a proline break, offering a convex surface towards the solvent area which is implicated in actin binding. The F-actin-binding model suggests that ABP34 binds to the side of the actin filament and residues 216-244 fit into a pocket between actin subdomains -1 and -2 through hydrophobic interactions. These studies provide insights into the calcium coordination in the EF-hand and F-actin-binding site in the C-domain of ABP34, which are associated through interdomain interactions. PMID:26327373

  20. Casimir effect with rough metallic mirrors

    SciTech Connect

    Neto, Paulo A. Maia; Lambrecht, Astrid; Reynaud, Serge

    2005-07-15

    We calculate the second-order roughness correction to the Casimir energy for two parallel metallic mirrors. Our results may also be applied to the plane-sphere geometry used in most experiments. The metallic mirrors are described by the plasma model, with arbitrary values for the plasma wavelength, the mirror separation, and the roughness correlation length, with the roughness amplitude remaining the smallest length scale for perturbation theory to hold. From the analysis of the intracavity field fluctuations, we obtain the Casimir energy correction in terms of generalized reflection operators, which account for diffraction and polarization coupling in the scattering by the rough surfaces. We present simple analytical expressions for several limiting cases, as well as numerical results that allow for a reliable calculation of the roughness correction in real experiments. The correction is larger than the result of the proximity force approximation, which is obtained from our theory as a limiting case (very smooth surfaces)

  1. Modeling surface roughness scattering in metallic nanowires

    SciTech Connect

    Moors, Kristof; Sorée, Bart; Magnus, Wim

    2015-09-28

    Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

  2. Effectiveness of Hair Bundle Motility as the Cochlear Amplifier

    PubMed Central

    Sul, Bora; Iwasa, Kuni H.

    2009-01-01

    Abstract The effectiveness of hair bundle motility in mammalian and avian ears is studied by examining energy balance for a small sinusoidal displacement of the hair bundle. The condition that the energy generated by a hair bundle must be greater than energy loss due to the shear in the subtectorial gap per hair bundle leads to a limiting frequency that can be supported by hair-bundle motility. Limiting frequencies are obtained for two motile mechanisms for fast adaptation, the channel re-closure model and a model that assumes that fast adaptation is an interplay between gating of the channel and the myosin motor. The limiting frequency obtained for each of these models is an increasing function of a factor that is determined by the morphology of hair bundles and the cochlea. Primarily due to the higher density of hair cells in the avian inner ear, this factor is ∼10-fold greater for the avian ear than the mammalian ear, which has much higher auditory frequency limit. This result is consistent with a much greater significance of hair bundle motility in the avian ear than that in the mammalian ear. PMID:19917218

  3. Mechanical Amplification Exhibited by Quiescent Saccular Hair Bundles

    PubMed Central

    Roongthumskul, Yuttana; Bozovic, Dolores

    2015-01-01

    Spontaneous oscillations exhibited by free-standing hair bundles from the Bullfrog sacculus suggest the existence of an active process that might underlie the exquisite sensitivity of the sacculus to mechanical stimulation. However, this spontaneous activity is suppressed by coupling to an overlying membrane, which applies a large mechanical load on the bundle. How a quiescent hair bundle utilizes its active process is still unknown. We studied the dynamics of motion of individual hair bundles under different offsets in the bundle position, and observed the occurrence of spikes in hair-bundle motion, associated with the generation of active work. These mechanical spikes can be evoked by a sinusoidal stimulus, leading to an amplified movement of the bundle with respect to the passive response. Amplitude gain reached as high as 100-fold at small stimulus amplitudes. Amplification of motion decreased with increasing amplitude of stimulation, ceasing at ∼6–12 pN stimuli. Results from numerical simulations suggest that the adaptation process, mediated by myosin 1c, is not required for the production of mechanical spikes. PMID:25564852

  4. Spontaneous Oscillation by Hair Bundles of the Bullfrog's Sacculus

    PubMed Central

    Martin, Pascal; Bozovic, D.; Choe, Y.; Hudspeth, A. J.

    2007-01-01

    One prominent manifestation of mechanical activity in hair cells is spontaneous otoacoustic emission, the unprovoked emanation of sound by an internal ear. Because active hair-bundle motility probably constitutes the active process of non-mammalian hair cells, we investigated the ability of hair bundles in the bullfrog's sacculus to produce oscillations that might underlie spontaneous otoacoustic emissions. When maintained in the ear's normal ionic milieu, many bundles oscillated spontaneously through distances as great as 80 nm at frequencies of 5-50 Hz. Whole-cell recording disclosed that the positive phase of movement was associated with the opening of transduction channels. Gentamicin, which blocks transduction channels, reversibly arrested oscillation; drugs that affect the cAMP phosphorylation pathway and might influence myosin's activity altered the rate of oscillation. Increasing the Ca2+ concentration rendered oscillations faster and smaller until they were suppressed; lowering the Ca2+ concentration moderately with chelators had the opposite effect. When a bundle was offset with a stimulus fiber, oscillations were transiently suppressed but gradually resumed. Loading a bundle by partial displacement clamping, which simulated the presence of the accessory structures to which a bundle is ordinarily attached, increased the frequency and diminished the magnitude of oscillation. These observations accord with a model in which oscillations arise from the interplay of the hair bundle's negative stiffness with the activity of adaptation motors and with Ca2+-dependent relaxation of gating springs. PMID:12805294

  5. Mechanical amplification exhibited by quiescent saccular hair bundles.

    PubMed

    Roongthumskul, Yuttana; Bozovic, Dolores

    2015-01-01

    Spontaneous oscillations exhibited by free-standing hair bundles from the Bullfrog sacculus suggest the existence of an active process that might underlie the exquisite sensitivity of the sacculus to mechanical stimulation. However, this spontaneous activity is suppressed by coupling to an overlying membrane, which applies a large mechanical load on the bundle. How a quiescent hair bundle utilizes its active process is still unknown. We studied the dynamics of motion of individual hair bundles under different offsets in the bundle position, and observed the occurrence of spikes in hair-bundle motion, associated with the generation of active work. These mechanical spikes can be evoked by a sinusoidal stimulus, leading to an amplified movement of the bundle with respect to the passive response. Amplitude gain reached as high as 100-fold at small stimulus amplitudes. Amplification of motion decreased with increasing amplitude of stimulation, ceasing at ∼6-12 pN stimuli. Results from numerical simulations suggest that the adaptation process, mediated by myosin 1c, is not required for the production of mechanical spikes. PMID:25564852

  6. Spontaneous oscillation by hair bundles of the bullfrog's sacculus.

    PubMed

    Martin, Pascal; Bozovic, D; Choe, Y; Hudspeth, A J

    2003-06-01

    One prominent manifestation of mechanical activity in hair cells is spontaneous otoacoustic emission, the unprovoked emanation of sound by an internal ear. Because active hair bundle motility probably constitutes the active process of nonmammalian hair cells, we investigated the ability of hair bundles in the bullfrog's sacculus to produce oscillations that might underlie spontaneous otoacoustic emissions. When maintained in the normal ionic milieu of the ear, many bundles oscillated spontaneously through distances as great as 80 nm at frequencies of 5-50 Hz. Whole-cell recording disclosed that the positive phase of movement was associated with the opening of transduction channels. Gentamicin, which blocks transduction channels, reversibly arrested oscillation; drugs that affect the cAMP phosphorylation pathway and might influence the activity of myosin altered the rate of oscillation. Increasing the Ca 2+ concentration rendered oscillations faster and smaller until they were suppressed; lowering the Ca 2+ concentration moderately with chelators had the opposite effect. When a bundle was offset with a stimulus fiber, oscillations were transiently suppressed but gradually resumed. Loading a bundle by partial displacement clamping, which simulated the presence of the accessory structures to which a bundle is ordinarily attached, increased the frequency and diminished the magnitude of oscillation. These observations accord with a model in which oscillations arise from the interplay of the hair bundle's negative stiffness with the activity of adaptation motors and with Ca 2+-dependent relaxation of gating springs. PMID:12805294

  7. Measurement of depletion-induced force in microtubule bundles

    NASA Astrophysics Data System (ADS)

    Hilitski, Fiodar; Ward, Andrew; Dogic, Zvonimir

    2014-03-01

    Microtubule (MT) bundles formed in the presence of non-adsorbing polymers - poly-ethylene glycol (PEG) or Dextran - are widely used in experimental active matter systems. However, many properties of such MT bundles have not been studied experimentally. In this work, we combine optical trapping techniques with an umbrella sampling method in order to measure the depletion force acting on individual microtubule in the axial direction within the bundle. We find depletion force is independent of bundle overlap length and measure its magnitude to be on the order of tens of kB/T μm. We explore the dependence of the depletion force on concentration of depletant (PEG 20K) as well as K+ ions (necessary for screening electrostatic repulsion between MT filaments). We also verify additivity of depletion interaction and confirm that force is increased by a factor of two for three-MT bundles. Additionally, our experimental technique allows us to probe interactions between MTs within the bundle. Experimental data suggests that filaments in the bundle interact only hydrodynamically when depletant concentrations are low enough; however, we observe onset of solid-like friction when osmotic pressure is increased above a certain threshold.

  8. Steric Effects Induce Geometric Remodeling of Actin Bundles in Filopodia.

    PubMed

    Dobramysl, Ulrich; Papoian, Garegin A; Erban, Radek

    2016-05-10

    Filopodia are ubiquitous fingerlike protrusions, spawned by many eukaryotic cells, to probe and interact with their environments. Polymerization dynamics of actin filaments, comprising the structural core of filopodia, largely determine their instantaneous lengths and overall lifetimes. The polymerization reactions at the filopodial tip require transport of G-actin, which enter the filopodial tube from the filopodial base and diffuse toward the filament barbed ends near the tip. Actin filaments are mechanically coupled into a tight bundle by cross-linker proteins. Interestingly, many of these proteins are relatively short, restricting the free diffusion of cytosolic G-actin throughout the bundle and, in particular, its penetration into the bundle core. To investigate the effect of steric restrictions on G-actin diffusion by the porous structure of filopodial actin filament bundle, we used a particle-based stochastic simulation approach. We discovered that excluded volume interactions result in partial and then full collapse of central filaments in the bundle, leading to a hollowed-out structure. The latter may further collapse radially due to the activity of cross-linking proteins, hence producing conical-shaped filament bundles. Interestingly, electron microscopy experiments on mature filopodia indeed frequently reveal actin bundles that are narrow at the tip and wider at the base. Overall, our work demonstrates that excluded volume effects in the context of reaction-diffusion processes in porous networks may lead to unexpected geometric growth patterns and complicated, history-dependent dynamics of intermediate metastable configurations. PMID:27166814

  9. Equivariant algebraic vector bundles over representations of reductive groups: theory.

    PubMed Central

    Masuda, M; Petrie, T

    1991-01-01

    Let G be a reductive algebraic group and let B be an affine variety with an algebraic action of G. Everything is defined over the field C of complex numbers. Consider the trivial G-vector bundle B x S = S over B where S is a G-module. From the endomorphism ring R of the G-vector bundle S a construction of G-vector bundles over B is given. The bundles constructed this way have the property that when added to S they are isomorphic to F + S for a fixed G-module F. For such a bundle E an invariant rho(E) is defined that lies in a quotient of R. This invariant allows us to distinguish nonisomorphic G-vector bundles. This is applied to the case where B is a G-module and, in that case, an invariant of the underlying equivariant variety is given too. These constructions and invariants are used to produce families of inequivalent G-vector bundles over G-modules and families of inequivalent G actions on affine spaces for some finite and some connected semisimple groups. PMID:11607220

  10. Stochastic Molecular Transport on Microtubule Bundles with Structural Defects

    NASA Astrophysics Data System (ADS)

    Gramlich, M. W.; Tabei, S. M. Ali

    Intracellular transport involves complex coordination of multiple components such as: the cytoskeletal network and molecular motors. Perturbations in this process can amplify over time and space, thereby affecting transport. One little studied component of transport are structural defects in the cytoskeletal network. In this talk we will present a stochastic model of the interaction of the molecular motor, kinesin-1, and a bundled cystoskeletal network of microtubules, and explicitly explore the role of microtubule ends (a type of defect) on long-range transport. We will show how different types of end distributions can ultimately result in the same observed transport behavior for bundles. We compare transport on completely uniform bundles, found in the axon, to completely random bundles, found in dendrites. Because of the un-biased random bundle nature, defects affect transport on dendrite bundles more than on uniform bundles in the axon. Further, defects act as large spatial-scale traps that result in random wait-times which have been assumed in previous models.

  11. Bundling actin filaments from membranes: some novel players

    PubMed Central

    Thomas, Clément

    2012-01-01

    Progress in live-cell imaging of the cytoskeleton has significantly extended our knowledge about the organization and dynamics of actin filaments near the plasma membrane of plant cells. Noticeably, two populations of filamentous structures can be distinguished. On the one hand, fine actin filaments which exhibit an extremely dynamic behavior basically characterized by fast polymerization and prolific severing events, a process referred to as actin stochastic dynamics. On the other hand, thick actin bundles which are composed of several filaments and which are comparatively more stable although they constantly remodel as well. There is evidence that the actin cytoskeleton plays critical roles in trafficking and signaling at both the cell cortex and organelle periphery but the exact contribution of actin bundles remains unclear. A common view is that actin bundles provide the long-distance tracks used by myosin motors to deliver their cargo to growing regions and accordingly play a particularly important role in cell polarization. However, several studies support that actin bundles are more than simple passive highways and display multiple and dynamic roles in the regulation of many processes, such as cell elongation, polar auxin transport, stomatal and chloroplast movement, and defense against pathogens. The list of identified plant actin-bundling proteins is ever expanding, supporting that plant cells shape structurally and functionally different actin bundles. Here I review the most recently characterized actin-bundling proteins, with a particular focus on those potentially relevant to membrane trafficking and/or signaling. PMID:22936939

  12. Computing Temperatures In Optically Pumped Laser Rods

    NASA Technical Reports Server (NTRS)

    Farrukh, Usamah O.

    1991-01-01

    Computer program presents new model solving temperature-distribution problem for laser rods of finite length and calculates both radial and axial components of temperature distributions in these rods. Contains several self-checking schemes to prevent over-writing of memory blocks and to provide simple tracing of information in case of trouble. Written in Microsoft FORTRAN 77.

  13. Tipping Time of a Quantum Rod

    ERIC Educational Resources Information Center

    Parrikar, Onkar

    2010-01-01

    The behaviour of a quantum rod, pivoted at its lower end on an impenetrable floor and restricted to moving in the vertical plane under the gravitational potential, is studied analytically under the approximation that the rod is initially localized to a "small-enough" neighbourhood around the point of classical unstable equilibrium. It is shown…

  14. Two-state approach to stochastic hair bundle dynamics

    NASA Astrophysics Data System (ADS)

    Clausznitzer, Diana; Lindner, Benjamin; Jülicher, Frank; Martin, Pascal

    2008-04-01

    Hair cells perform the mechanoelectrical transduction of sound signals in the auditory and vestibular systems of vertebrates. The part of the hair cell essential for this transduction is the so-called hair bundle. In vitro experiments on hair cells from the sacculus of the American bullfrog have shown that the hair bundle comprises active elements capable of producing periodic deflections like a relaxation oscillator. Recently, a continuous nonlinear stochastic model of the hair bundle motion [Nadrowski , Proc. Natl. Acad. Sci. U.S.A. 101, 12195 (2004)] has been shown to reproduce the experimental data in stochastic simulations faithfully. Here, we demonstrate that a binary filtering of the hair bundle's deflection (experimental data and continuous hair bundle model) does not change significantly the spectral statistics of the spontaneous as well as the periodically driven hair bundle motion. We map the continuous hair bundle model to the FitzHugh-Nagumo model of neural excitability and discuss the bifurcations between different regimes of the system in terms of the latter model. Linearizing the nullclines and assuming perfect time-scale separation between the variables we can map the FitzHugh-Nagumo system to a simple two-state model in which each of the states corresponds to the two possible values of the binary-filtered hair bundle trajectory. For the two-state model, analytical expressions for the power spectrum and the susceptibility can be calculated [Lindner and Schimansky-Geier, Phys. Rev. E 61, 6103 (2000)] and show the same features as seen in the experimental data as well as in simulations of the continuous hair bundle model.

  15. Vortex Noise from Rotating Cylindrical Rods

    NASA Technical Reports Server (NTRS)

    Stowell, E Z; Deming, A F

    1935-01-01

    A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula von Karman. From the spectrum estimates are made of the distribution of acoustical power along the rod, the amount of air concerned in sound production, the "equivalent size" of the vortices, and the acoustical energy content for each vortex.

  16. Rod-Coil Block Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Kinder, James D. (Inventor)

    2005-01-01

    This invention is a series of rod-coil block polyimide copolymers that are easy to fabricate into mechanically resilient films with acceptable ionic or protonic conductivity at a variety of temperatures. The copolymers consist of short-rigid polyimide rod segments alternating with polyether coil segments. The rods and coil segments can be linear, branched or mixtures of linear and branched segments. The highly incompatible rods and coil segments phase separate, providing nanoscale channels for ion conduction. The polyimide segments provide dimensional and mechanical stability and can be functionalized in a number of ways to provide specialized functions for a given application. These rod-coil black polyimide copolymers are particularly useful in the preparation of ion conductive membranes for use in the manufacture of fuel cells and lithium based polymer batteries.

  17. Modifications of bundles, elliptic integrable systems, and related problems

    NASA Astrophysics Data System (ADS)

    Zotov, A. V.; Smirnov, A. V.

    2013-10-01

    We describe a construction of elliptic integrable systems based on bundles with nontrivial characteristic classes, especially attending to the bundle-modification procedure, which relates models corresponding to different characteristic classes. We discuss applications and related problems such as the Knizhnik-Zamolodchikov-Bernard equations, classical and quantum R-matrices, monopoles, spectral duality, Painlevé equations, and the classical-quantum correspondence. For an SL(N,ℂ)-bundle on an elliptic curve with nontrivial characteristic classes, we obtain equations of isomonodromy deformations.

  18. Structural Transitions of F-Actin:Espin Bundles

    NASA Astrophysics Data System (ADS)

    Purdy, Kirstin; Bartles, James; Wong, Gerard

    2006-03-01

    Espin is an actin bundling protein involved in the formation of the parallel bundles of filamentous actin in hair cell stereocilia. Mutations in espin are implicated in deafness phenotypes in mice and humans. We present measurements of the F-actin structures induced by wild type and by mutated espin obtained via small angle x-ray scattering and fluorescence microscopy. We found that wild type espin induced a paracrystalline hexagonal array of twisted F-actin, whereas the mutated espin only condensed the F-actin into a nematic-like phase. The possibility of coexisting nematic and bundled actin in mixtures containing both mutant and wild type espins was also investigated.

  19. Method and device for tensile testing of cable bundles

    SciTech Connect

    Robertson, Lawrence M; Ardelean, Emil V; Goodding, James C; Babuska, Vit

    2012-10-16

    A standard tensile test device is improved to accurately measure the mechanical properties of stranded cables, ropes, and other composite structures wherein a witness is attached to the top and bottom mounting blocks holding the cable under test. The witness is comprised of two parts: a top and a bottom rod of similar diameter with the bottom rod having a smaller diameter stem on its upper end and the top rod having a hollow opening in its lower end into which the stem fits forming a witness joint. A small gap is present between the top rod and the larger diameter portion of the bottom rod. A standard extensometer is attached to the top and bottom rods of the witness spanning this small witness gap. When a force is applied to separate the mounting blocks, the gap in the witness expands the same length that the entire test specimen is stretched.

  20. On the roughness measurement on knee prostheses.

    PubMed

    Jaber, Sami Abdel; Ruggiero, Alessandro; Battaglia, Santina; Affatato, Saverio

    2015-01-01

    The majority of total knee replacements currently implanted present an articulation composed of two metal parts, femoral and tibial components, between which there is a polyethylene insert serving as a bearing surface. The finishing surface of the metal components is a very important factor in minimizing the polyethylene wear rate and, later, the gradual production of metal and plastic debris. Considering the role of surface roughness on volumetric wear rates, the purpose of this study is to develop a protocol for the roughness characterization of total knee prosthesis (TKP) metal components, taking into consideration a limited number of points on each surface. Six mobile TKP of different sizes (three size 2 and three size 6) were tested on a knee joint simulator to compare the wear behavior of each group. After 2 million cycles the weight loss by the polyethylene inserts was measured with gravimetric method and the surface roughness of the metallic components was assessed in terms of average surface roughness, Ra, skewness, Rsk, and total roughness, Rt. Roughness measurement involved 29 points on each femoral condyle and 26 points on each metal tibial plate. The data collected has shown an increased roughness upon wear testing for both the investigated TKP sizes. No statistical differences were observed between the two groups for both the parameters Ra, Rsk, and Rt. The surface of all metallic components became more negatively skewed, indicating diminishing peaks. The various parameters were correlated to the volumetric loss using a linear regression analysis. PMID:25588764

  1. Thermal contact conductance of spherical, rough metals

    SciTech Connect

    Lambert, M.A.; Fletcher, L.S.

    1996-12-31

    Junction thermal conductance is an important consideration in such applications as thermally induced stresses in supersonic and hypersonic flight vehicles, nuclear reactor cooling, electronics packaging, spacecraft thermal control, gas turbine and internal combustion engine cooling, and cryogenic liquid storage. A fundamental problem in analyzing and predicting junction thermal conductance is thermal contact conductance of non-flat, rough metals. Workable models have been previously derived for the limiting idealized cases of flat, rough and spherical, smooth surfaces. However, until now, no tractable models have been advanced for non-flat, rough surfaces (so called engineering surfaces) which are much more commonly dealt with in practice. The present investigation details the synthesis of previously derived models for macroscopically non-uniform thermal contact conductance and contact of non-flat, rough spheres, into a thermo-mechanical model, its refinement, and its presentation in an easily applied format. The present model is compared to representative experimental conductance results form the literature for stainless steel 304 with widely varying flatness deviation and roughness. Also included in the comparisons is a previous, often cited model for flat, rough metals to which the present model reduces in the limit of flat surfaces. The present model agrees well with the experimental results over the wide ranges of flatness deviation and roughness for which data was available. Conversely, the previous, well known model becomes increasingly overpredictive with increasing flatness deviation.

  2. Eulerian Formulation of Spatially Constrained Elastic Rods

    NASA Astrophysics Data System (ADS)

    Huynen, Alexandre

    Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is in contact with a stiff constraining surface. The research work presented in this doctoral dissertation formulates a computational model for the solution of elastic rods constrained inside or around frictionless tube-like surfaces. The segmentation strategy adopted to cope with this complex class of problems consists in sequencing the global problem into, comparatively simpler, elementary problems either in continuous contact with the constraint or contact-free between their extremities. Within the conventional Lagrangian formulation of elastic rods, this approach is however associated with two major drawbacks. First, the boundary conditions specifying the locations of the rod centerline at both extremities of each elementary problem lead to the establishment of isoperimetric constraints, i.e., integral constraints on the unknown length of the rod. Second, the assessment of the unilateral contact condition requires, in principle, the comparison of two curves parametrized by distinct curvilinear coordinates, viz. the rod centerline and the constraint axis. Both conspire to burden the computations associated with the method. To streamline the solution along the elementary problems and rationalize the assessment of the unilateral contact condition, the rod governing equations are reformulated within the Eulerian framework of the constraint. The methodical exploration of both types of elementary problems leads to specific formulations of the rod governing equations that stress the profound connection between the mechanics of the rod and the geometry of the constraint surface. The proposed Eulerian reformulation, which restates the rod local equilibrium in terms of the curvilinear coordinate associated with the constraint axis, describes the rod deformed configuration

  3. Concise Care Bundles In Acute Medicine

    PubMed Central

    Kivlin, Jude; Altemimi, Harith

    2015-01-01

    The Queen Elizabeth Hospital in King's Lynn, Norfolk is a 488 bed hospital providing services to approximately 331,000 people across 750 square miles. In 2012 a need was recognised for documentation (pathways) in a practical format to increase usage of national guidelines and facilitate adherence to best practice (gold standards of care) that could be easily version controlled, auditable and provide support in clinical decision-making by junior doctors. BMJ Action Sets[1] fulfilled the brief with expert knowledge, version control and support, though they were deemed too lengthy and unworkable in fast paced settings like the medical assessment unit; they formed the base creation of concise care bundles (CCB). CCB were introduced for 21 clinical presentations and one procedure. Outcomes were fully audited and showed significant improvement in a range of measures, including an increase in completions of CHADVASC score in atrial fibrillation, antibiotics prescribed per protocol in chronic obstructive pulmonary disease (COPD), and Blatchford score recorded for patients presenting with upper gastrointestinal bleed. PMID:26734437

  4. Microendoscopic holography with flexible fiber bundle

    NASA Astrophysics Data System (ADS)

    Coquoz, Olivier; Depeursinge, Christian D.; Conde, Ramiro; de Haller, Emmanuel B.

    1994-05-01

    An in situ holographic technique, involving the use of a flexible miniaturized endoscope (diameter less than 1 mm) coupled to a CCD camera, to record the hologram, has been developed for medical applications. The hologram is formed, by reflection, on the tip of a multimode fiber bundle (MMB), sampled, and then treated electronically. The image is reconstructed numerically, providing more flexibility to the holographic process. Reconstructed images show the capability of the microendoscopic system to restore 3D informations of the observed scene. The limitations of the holographic approach with the microendoscope have been evaluated and discussed in terms of the resolution limit. In particular, the low frequency sampling of the hologram through the MMB is not a limiting factor for the range of observation distance investigated (4 - 10 mm). A good accordance between the experimental results and the theoretical predictions was found by comparing the cut-off frequency obtained. Our results show that, for the considered observation distances, objects of a few micrometers can be clearly identified. The different sources of noise are analyzed and their influence on the quality of the reconstructed image have been quantified.

  5. WEAVE MOS fibre bundle test plan

    NASA Astrophysics Data System (ADS)

    Sayède, Frédéric; Guinouard, Isabelle; Fasola, Gilles; Lhome, Emilie; Amans, Jean-Philippe; Bonifacio, Piercarlo; Abrams, Don Carlos; Middleton, Kevin; Dalton, Gavin; Aguerri, J. Alfonso L.; Trager, Scott C.; Loeb, Avi

    2014-07-01

    WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. WEAVE mainly aims at spectroscopic follow-up of ground-based (e.g. LOFAR) and space-based (GAIA) surveys. The facility consists of a new 2-degree field-of-view prime focus corrector with a 1000- multiplex fibre positioner, a small number of individually deployable integral field units, and a large single integral field unit. The IFUs (Integral Field Units) and the MOS fibres can be used to feed a dual-beam spectrograph that will provide full coverage of the majority of the visible spectrum in a single exposure at a spectral resolution of ~5000 or modest wavelength coverage in both arms at a resolution ~20000. The instrument is expected to be on-sky by 2017 to provide spectroscopic sampling of the fainter end of the Gaia astrometric catalogue, chemical labeling of stars to V~17, and dedicated follow up of substantial numbers of sources from the medium deep LOFAR surveys. After a brief description of the MOS fibre bundle, we described the proposed test plan and the test bench of the 2x1000 WEAVE MOS fibres. The test bench allows us to evaluate the Focal Ratio Degradation and the throughput of the fibers fitted with their buttons and slitlets.

  6. Turbulent flow in smooth and rough pipes.

    PubMed

    Allen, J J; Shockling, M A; Kunkel, G J; Smits, A J

    2007-03-15

    Recent experiments at Princeton University have revealed aspects of smooth pipe flow behaviour that suggest a more complex scaling than previously noted. In particular, the pressure gradient results yield a new friction factor relationship for smooth pipes, and the velocity profiles indicate the presence of a power-law region near the wall and, for Reynolds numbers greater than about 400x103 (R+>9x103), a logarithmic region further out. New experiments on a rough pipe with a honed surface finish with krms/D=19.4x10-6, over a Reynolds number range of 57x103-21x106, show that in the transitionally rough regime this surface follows an inflectional friction factor relationship rather than the monotonic relationship given in the Moody diagram. Outer-layer scaling of the mean velocity data and streamwise turbulence intensities for the rough pipe show excellent collapse and provide strong support for Townsend's outer-layer similarity hypothesis for rough-walled flows. The streamwise rough-wall spectra also agree well with the corresponding smooth-wall data. The pipe exhibited smooth behaviour for ks+ < or =3.5, which supports the suggestion that the original smooth pipe was indeed hydraulically smooth for ReD< or =24x106. The relationship between the velocity shift, DeltaU/utau, and the roughness Reynolds number, ks+, has been used to generalize the form of the transition from smooth to fully rough flow for an arbitrary relative roughness krms/D. These predictions apply for honed pipes when the separation of pipe diameter to roughness height is large, and they differ significantly from the traditional Moody curves. PMID:17244585

  7. Layering of ionic liquids on rough surfaces

    NASA Astrophysics Data System (ADS)

    Sheehan, Alexis; Jurado, L. Andres; Ramakrishna, Shivaprakash N.; Arcifa, Andrea; Rossi, Antonella; Spencer, Nicholas D.; Espinosa-Marzal, Rosa M.

    2016-02-01

    Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact.Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact. Electronic supplementary information (ESI) available: Optimized geometries and sizes for [HMIM] Ntf2, SEM images of the smooth and rough colloids, frequency of occurrence of layering in the resolved force-distance curves for all investigated systems with [HMIM] Ntf2, layer size and layering force measured with a sharp tip on mica for the same IL, and results of the kinetics experiments. See DOI: 10.1039/c5nr07805a

  8. Understanding EUV mask blank surface roughness induced LWR and associated roughness requirement

    SciTech Connect

    Yan, Pei-Yang; Zhang, Guojing; Gullickson, Eric M.; Goldberg, Kenneth A.; Benk, Markus P.

    2015-03-01

    Extreme ultraviolet lithography (EUVL) mask multi-layer (ML) blank surface roughness specification historically comes from blank defect inspection tool requirement. Later, new concerns on ML surface roughness induced wafer pattern line width roughness (LWR) arise. In this paper, we have studied wafer level pattern LWR as a function of EUVL mask surface roughness via High-NA Actinic Reticle Review Tool. We found that the blank surface roughness induced LWR at current blank roughness level is in the order of 0.5nm 3σ for NA=0.42 at the best focus. At defocus of ±40nm, the corresponding LWR will be 0.2nm higher. Further reducing EUVL mask blank surface roughness will increase the blank cost with limited benefit in improving the pattern LWR, provided that the intrinsic resist LWR is in the order of 1nm and above.

  9. Numerical Schemes for Rough Parabolic Equations

    SciTech Connect

    Deya, Aurelien

    2012-04-15

    This paper is devoted to the study of numerical approximation schemes for a class of parabolic equations on (0,1) perturbed by a non-linear rough signal. It is the continuation of Deya (Electron. J. Probab. 16:1489-1518, 2011) and Deya et al. (Probab. Theory Relat. Fields, to appear), where the existence and uniqueness of a solution has been established. The approach combines rough paths methods with standard considerations on discretizing stochastic PDEs. The results apply to a geometric 2-rough path, which covers the case of the multidimensional fractional Brownian motion with Hurst index H>1/3.

  10. Giant persistent photoconductivity in rough silicon nanomembranes.

    PubMed

    Feng, Ping; Mönch, Ingolf; Harazim, Stefan; Huang, Gaoshan; Mei, Yongfeng; Schmidt, Oliver G

    2009-10-01

    This paper reports the observation of giant persistent photoconductivity from rough Si nanomembranes. When exposed to light, the current in p-type Si nanomembranes is enhanced by roughly 3 orders of magnitude in comparison with that in the dark and can persist for days at a high conductive state after the light is switched off. An applied gate voltage can tune the persistent photocurrent and accelerate the response to light. By analyzing the band structure of the devices and the surfaces through various coatings, we attribute the observed effect to hole-localized regions in Si nanomembranes due to the rough surfaces, where light can activate the confined holes. PMID:19637888

  11. Nanoscale roughness micromilled silica evanescent refractometer.

    PubMed

    Carpenter, Lewis G; Cooper, Peter A; Holmes, Christopher; Gawith, Corin B E; Gates, James C; Smith, Peter G R

    2015-01-26

    We demonstrate machining of precision slots in silica with nanoscale roughness for applications in photonics. Using our in-house developed milling system we have achieved machined slots with surface roughness of 3.0 nm (Sa) and 17 µm depth of cut. This result represents eight times improvement in surface roughness and forty times increase in depth of cut than previously reported. We also demonstrate integration of these milled slots with UV-written waveguides and Bragg gratings to create optical refractometers, based on monitoring Fabry-Pérot spectral fringe changes. PMID:25835860

  12. Assembly of hair bundles, an amazing problem for cell biology

    PubMed Central

    Barr-Gillespie, Peter-G.

    2015-01-01

    The hair bundle—the sensory organelle of inner-ear hair cells of vertebrates—exemplifies the ability of a cell to assemble complex, elegant structures. Proper construction of the bundle is required for proper mechanotransduction in response to external forces and to transmit information about sound and movement. Bundles contain tightly controlled numbers of actin-filled stereocilia, which are arranged in defined rows of precise heights. Indeed, many deafness mutations that disable hair-cell cytoskeletal proteins also disrupt bundles. Bundle assembly is a tractable problem in molecular and cellular systems biology; the sequence of structural changes in stereocilia is known, and a modest number of proteins may be involved. PMID:26229154

  13. National Partnership for Maternal Safety: Consensus Bundle on Obstetric Hemorrhage.

    PubMed

    Main, Elliott K; Goffman, Dena; Scavone, Barbara M; Low, Lisa Kane; Bingham, Debra; Fontaine, Patricia L; Gorlin, Jed B; Lagrew, David C; Levy, Barbara S

    2015-07-01

    Hemorrhage is the most frequent cause of severe maternal morbidity and preventable maternal mortality and therefore is an ideal topic for the initial national maternity patient safety bundle. These safety bundles outline critical clinical practices that should be implemented in every maternity unit. They are developed by multidisciplinary work groups of the National Partnership for Maternal Safety under the guidance of the Council on Patient Safety in Women's Health Care. The safety bundle is organized into four domains: Readiness, Recognition and Prevention, Response, and Reporting and System Learning. Although the bundle components may be adapted to meet the resources available in individual facilities, standardization within an institution is strongly encouraged. References contain sample resources and "Potential Best Practices" to assist with implementation. PMID:26241269

  14. 15. VIEW OF SHINGLES BUNDLED, PLACED ON PALLET, AND READIED ...

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

    15. VIEW OF SHINGLES BUNDLED, PLACED ON PALLET, AND READIED FOR FORKLIFT OPERATOR TO MOVE PALLET OF SHINGLES TO LOADING DOCK - Lester Shingle Mill, 1602 North Eighteenth Street, Sweet Home, Linn County, OR

  15. Mechanical Models of Microtubule Bundle Collapse in Alzheimer's Disease

    NASA Astrophysics Data System (ADS)

    Sendek, Austin; Singh, Rajiv; Cox, Daniel

    2013-03-01

    Amyloid-beta aggregates initiate Alzheimer's disease, and downstream trigger degradation of tau proteins that act as microtubule bundle stabilizers and mechanical spacers. Currently it is unclear which of tau cutting by proteases, tau phosphorylation, or tau aggregation are responsible for cytoskeleton degradation., We construct a percolation simulation of the microtubule bundle using a molecular spring model for the taus and including depletion force attraction between microtubules and membrane/actin cytoskeletal surface tension. The simulation uses a fictive molecular dynamics to model the motion of the individual microtubules within the bundle as a result of random tau removal, and calculates the elastic modulus of the bundle as the tau concentration falls. We link the tau removal steps to kinetic tau steps in various models of tau degradation. Supported by US NSF Grant DMR 1207624

  16. SEU43 fuel bundle shielding analysis during spent fuel transport

    SciTech Connect

    Margeanu, C. A.; Ilie, P.; Olteanu, G.

    2006-07-01

    The basic task accomplished by the shielding calculations in a nuclear safety analysis consist in radiation doses calculation, in order to prevent any risks both for personnel protection and impact on the environment during the spent fuel manipulation, transport and storage. The paper investigates the effects induced by fuel bundle geometry modifications on the CANDU SEU spent fuel shielding analysis during transport. For this study, different CANDU-SEU43 fuel bundle projects, developed in INR Pitesti, have been considered. The spent fuel characteristics will be obtained by means of ORIGEN-S code. In order to estimate the corresponding radiation doses for different measuring points the Monte Carlo MORSE-SGC code will be used. Both codes are included in ORNL's SCALE 5 programs package. A comparison between the considered SEU43 fuel bundle projects will be also provided, with CANDU standard fuel bundle taken as reference. (authors)

  17. Heat transfer characteristics of tube bundles during boiling in vacuum

    NASA Astrophysics Data System (ADS)

    Slesarenko, V. N.; Zakharov, G. A.

    1992-06-01

    Heat transfer during boiling in vacuum was compared experimentally for single tubes, rows of tube, and tube bundles to analyze characteristic properties of vaporization under such conditions. Relations for calculating heat transfer coefficients are proposed.

  18. Bundles of Norms About Teen Sex and Pregnancy.

    PubMed

    Mollborn, Stefanie; Sennott, Christie

    2015-09-01

    Teen pregnancy is a cultural battleground in struggles over morality, education, and family. At its heart are norms about teen sex, contraception, pregnancy, and abortion. Analyzing 57 interviews with college students, we found that "bundles" of related norms shaped the messages teens hear. Teens did not think their communities encouraged teen sex or pregnancy, but normative messages differed greatly, with either moral or practical rationalizations. Teens readily identified multiple norms intended to regulate teen sex, contraception, abortion, childbearing, and the sanctioning of teen parents. Beyond influencing teens' behavior, norms shaped teenagers' public portrayals and post hoc justifications of their behavior. Although norm bundles are complex to measure, participants could summarize them succinctly. These bundles and their conflicting behavioral prescriptions create space for human agency in negotiating normative pressures. The norm bundles concept has implications for teen pregnancy prevention policies and can help revitalize social norms for understanding health behaviors. PMID:25387911

  19. Topological T-duality for torus bundles with monodromy

    NASA Astrophysics Data System (ADS)

    Baraglia, David

    2015-05-01

    We give a simplified definition of topological T-duality that applies to arbitrary torus bundles. The new definition does not involve Chern classes or spectral sequences, only gerbes and morphisms between them. All the familiar topological conditions for T-duals are shown to follow. We determine necessary and sufficient conditions for existence of a T-dual in the case of affine torus bundles. This is general enough to include all principal torus bundles as well as torus bundles with arbitrary monodromy representations. We show that isomorphisms in twisted cohomology, twisted K-theory and of Courant algebroids persist in this general setting. We also give an example where twisted K-theory groups can be computed by iterating T-duality.

  20. National Partnership for Maternal Safety: Consensus Bundle on Venous Thromboembolism.

    PubMed

    D'Alton, Mary E; Friedman, Alexander M; Smiley, Richard M; Montgomery, Douglas M; Paidas, Michael J; D'Oria, Robyn; Frost, Jennifer L; Hameed, Afshan B; Karsnitz, Deborah; Levy, Barbara S; Clark, Steven L

    2016-01-01

    Obstetric venous thromboembolism is a leading cause of severe maternal morbidity and mortality. Maternal death from thromboembolism is amenable to prevention, and thromboprophylaxis is the most readily implementable means of systematically reducing the maternal death rate. Observational data support the benefit of risk-factor-based prophylaxis in reducing obstetric thromboembolism. This bundle, developed by a multidisciplinary working group and published by the National Partnership for Maternal Safety under the guidance of the Council on Patient Safety in Women's Health Care, supports routine thromboembolism risk assessment for obstetric patients, with appropriate use of pharmacologic and mechanical thromboprophylaxis. Safety bundles outline critical clinical practices that should be implemented in every maternity unit. The safety bundle is organized into four domains: Readiness, Recognition, Response, and Reporting and Systems Learning. Although the bundle components may be adapted to meet the resources available in individual facilities, standardization within an institution is strongly encouraged. PMID:27619099

  1. Control Rod Malfunction at the NRAD Reactor

    SciTech Connect

    Thomas L. Maddock

    2010-05-01

    The neutron Radiography Reactor (NRAD) is a training, research, and isotope (TRIGA) reactor located at the INL. The reactor is normally shut down by the insertion of three control rods that drop into the core when power is removed from electromagnets. During a routine shutdown, indicator lights on the console showed that one of the control rods was not inserted. It was initially thought that the indicator lights were in error because of a limit switch that was out of adjustment. Through further testing, it was determined that the control rod did not drop when the scram switch was initially pressed. The control rod anomaly led to a six month shutdown of the reactor and an in depth investigation of the reactor protective system. The investigation looked into: scram switch operation, console modifications, and control rod drive mechanisms. A number of latent issues were discovered and corrected during the investigation. The cause of the control rod malfunction was found to be a buildup of corrosion in the control rod drive mechanism. The investigation resulted in modifications to equipment, changes to both operation and maintenance procedures, and additional training. No reoccurrences of the problem have been observed since corrective actions were implemented.

  2. DEVICE FOR CONTROLLING INSERTION OF ROD

    DOEpatents

    Beaty, B.J.

    1958-10-14

    A device for rapidly inserting a safety rod into a nuclear reactor upon a given signal or in the event of a power failure in order to prevent the possibility of extensive damage caused by a power excursion is described. A piston is slidably mounted within a vertical cylinder with provision for an electromagnetic latch at the top of the cylinder. This assembly, with a safety rod attached to the piston, is mounted over an access port to the core region of the reactor. The piston is normally latched at the top of the cylinder with the safety rod clear of the core area, however, when the latch is released, the piston and rod drop by their own weight to insert the rod. Vents along the side of the cylinder permit the escape of the air entrapped under the piston over the greater part of the distance, however, at the end of the fall the entrapped air is compressed thereby bringing the safety rod gently to rest, thus providing for a rapid automatic insertion of the rod with a minimum of structural shock.

  3. Granular materials interacting with thin flexible rods

    NASA Astrophysics Data System (ADS)

    Neto, Alfredo Gay; Campello, Eduardo M. B.

    2016-01-01

    In this work, we develop a computational model for the simulation of problems wherein granular materials interact with thin flexible rods. We treat granular materials as a collection of spherical particles following a discrete element method (DEM) approach, while flexible rods are described by a large deformation finite element (FEM) rod formulation. Grain-to-grain, grain-to-rod, and rod-to-rod contacts are fully permitted and resolved. A simple and efficient strategy is proposed for coupling the motion of the two types (discrete and continuum) of materials within an iterative time-stepping solution scheme. Implementation details are shown and discussed. Validity and applicability of the model are assessed by means of a few numerical examples. We believe that robust, efficiently coupled DEM-FEM schemes can be a useful tool to the simulation of problems wherein granular materials interact with thin flexible rods, such as (but not limited to) bombardment of grains on beam structures, flow of granular materials over surfaces covered by threads of hair in many biological processes, flow of grains through filters and strainers in various industrial segregation processes, and many others.

  4. More on the penetration of yawed rods

    NASA Astrophysics Data System (ADS)

    Rosenberg, Z.; Dekel, E.; Ashuach, Y.

    2006-08-01

    One of the most complex processes, in the field of terminal ballistics, is that of yawed impact of long rods. In spite of many experimental observations, and some analytical modeling, a clear picture of this issue is still lacking. In order to gain some insight into the operating mechanisms, we developed a simple engineering model which considers the yawed rod as a series of small disks. We then define the effective length and diameter of the rod by considering those disks which are going to hit the initial crater which is opened by the impact. We also performed a series of 3D numerical simulations with various L/D tungsten alloy rods impacting a steel target, at yaws in the full range of 0-90^circ. We analyzed the results of these simulations in terms of the normalized penetration (P/D), where D is the rod diameter, and looked for systematic trends in the results for the various rods. The agreement between our model predictions and both experimental data and simulation results is quite good. Based on this agreement we can highlight some new features of the penetration process of yawed rods.

  5. Reversible separation of single-walled carbon nanotubes in bundles

    SciTech Connect

    Sahoo, Sangeeta; Lastella, Sarah; Maranganti, Ravi; Sharma, Pradeep; Mallick, Govind; Karna, Shashi; Ajayan, Pulickel M.

    2008-08-25

    We show that electrostatic charging of nanotubes and the consequent repulsion can lead to reversible separation of individual single-walled carbon nanotubes in bundles. Low-energy electron beam irradiation leads to this completely reversible phenomenon. A simple semianalytical model is used to explain the observed separation mechanism. The reversibility of the separation process is attributed to discharging and thermal-fluctuation induced motion of the nanotubes in ambient air. Further, the separation impacts the electrical conductance of small nanotube bundled devices.

  6. Subdigital setae of chameleon feet: Friction-enhancing microstructures for a wide range of substrate roughness

    PubMed Central

    Spinner, Marlene; Westhoff, Guido; Gorb, Stanislav N.

    2014-01-01

    Hairy adhesive systems of microscopic setae with triangular flattened tips have evolved convergently in spiders, insects and arboreal lizards. The ventral sides of the feet and tails in chameleons are also covered with setae. However, chameleon setae feature strongly elongated narrow spatulae or fibrous tips. The friction enhancing function of these microstructures has so far only been demonstrated in contact with glass spheres. In the present study, the frictional properties of subdigital setae of Chamaeleo calyptratus were measured under normal forces in the physical range on plane substrates having different roughness. We showed that chameleon setae maximize friction on a wide range of substrate roughness. The highest friction was measured on asperities of 1 μm. However, our observations of the climbing ability of Ch. calyptratus on rods of different diameters revealed that also claws and grasping feet are additionally responsible for the force generation on various substrates during locomotion. PMID:24970387

  7. Subdigital setae of chameleon feet: Friction-enhancing microstructures for a wide range of substrate roughness

    NASA Astrophysics Data System (ADS)

    Spinner, Marlene; Westhoff, Guido; Gorb, Stanislav N.

    2014-06-01

    Hairy adhesive systems of microscopic setae with triangular flattened tips have evolved convergently in spiders, insects and arboreal lizards. The ventral sides of the feet and tails in chameleons are also covered with setae. However, chameleon setae feature strongly elongated narrow spatulae or fibrous tips. The friction enhancing function of these microstructures has so far only been demonstrated in contact with glass spheres. In the present study, the frictional properties of subdigital setae of Chamaeleo calyptratus were measured under normal forces in the physical range on plane substrates having different roughness. We showed that chameleon setae maximize friction on a wide range of substrate roughness. The highest friction was measured on asperities of 1 μm. However, our observations of the climbing ability of Ch. calyptratus on rods of different diameters revealed that also claws and grasping feet are additionally responsible for the force generation on various substrates during locomotion.

  8. Effect of Surface Roughness on Hydrodynamic Bearings

    NASA Technical Reports Server (NTRS)

    Majumdar, B. C.; Hamrock, B. J.

    1981-01-01

    A theoretical analysis on the performance of hydrodynamic oil bearings is made considering surface roughness effect. The hydrodynamic as well as asperity contact load is found. The contact pressure was calculated with the assumption that the surface height distribution was Gaussian. The average Reynolds equation of partially lubricated surface was used to calculate hydrodynamic load. An analytical expression for average gap was found and was introduced to modify the average Reynolds equation. The resulting boundary value problem was then solved numerically by finite difference methods using the method of successive over relaxation. The pressure distribution and hydrodynamic load capacity of plane slider and journal bearings were calculated for various design data. The effects of attitude and roughness of surface on the bearing performance were shown. The results are compared with similar available solution of rough surface bearings. It is shown that: (1) the contribution of contact load is not significant; and (2) the hydrodynamic and contact load increase with surface roughness.

  9. Simplified models for mask roughness induced LER

    SciTech Connect

    McClinton, Brittany; Naulleau, Patrick

    2011-02-21

    The ITRS requires < 1.2nm line-edge roughness (LER) for the 22nm half-pitch node. Currently, we can consistently achieve only about 3nm LER. Further progress requires understanding the principle causes of LER. Much work has already been done on how both the resist and LER on the mask effect the final printed LER. What is poorly understood, however, is the extent to which system-level effects such as mask surface roughness, illumination conditions, and defocus couple to speckle at the image plane, and factor into LER limits. Presently, mask-roughness induced LER is studied via full 2D aerial image modeling and subsequent analysis of the resulting image. This method is time consuming and cumbersome. It is, therefore, the goal of this research to develop a useful 'rule-of-thumb' analytic model for mask roughness induced LER to expedite learning and understanding.

  10. Surface roughness effects on bidirectional reflectance

    NASA Technical Reports Server (NTRS)

    Smith, T. F.; Hering, R. G.

    1972-01-01

    An experimental study of surface roughness effects on bidirectional reflectance of metallic surfaces is presented. A facility capable of irradiating a sample from normal to grazing incidence and recording plane of incidence bidirectional reflectance measurements was developed. Samples consisting of glass, aluminum alloy, and stainless steel materials were selected for examination. Samples were roughened using standard grinding techniques and coated with a radiatively opaque layer of pure aluminum. Mechanical surface roughness parameters, rms heights and rms slopes, evaluated from digitized surface profile measurements are less than 1.0 micrometers and 0.28, respectively. Rough surface specular, bidirectional, and directional reflectance measurements for selected values of polar angle of incidence and wavelength of incident energy within the spectral range of 1 to 14 micrometers are reported. The Beckmann bidirectional reflectance model is compared with reflectance measurements to establish its usefulness in describing the magnitude and spatial distribution of energy reflected from rough surfaces.

  11. Plantain fibre bundles isolated from Colombian agro-industrial residues.

    PubMed

    Gañán, Piedad; Zuluaga, Robin; Restrepo, Adriana; Labidi, Jalel; Mondragon, Iñaki

    2008-02-01

    Comestible fruit production from Musaceas plants is an important economical activity in developing countries like Colombia. However, it generates a large amount of agro-industrial residues. Some of them are a potential resource of natural fibres, which can be used as reinforcement for composite materials. In this work, a series of commercial plantain (Musa AAB, cv "Dominico Harton") fibre bundles extracted from pseudostem, leaf sheath and rachis agricultural wastes were analyzed. Mechanical decortication and biological retting processes were used during fiber extraction. No significant differences in composition of vascular bundles were observed for both extraction processes. Gross morphological characteristics and mechanical behavior have been evaluated. Conducting tissues with spiral-like arrangement are observed attached to fibre bundles. This fact suggests a big amount of these tissues in commercial plantain plants. Both used extraction methods are not enough to remove them. Pseudostem fibre bundles have higher specific strength and modulus and lower strain at break than leaf sheath and rachis fibre bundles, having values comparable to other lignocellulosic fibres bundles. PMID:17350832

  12. A Radiologist's Primer on Bundles and Care Episodes.

    PubMed

    Seidenwurm, David; Lexa, Frank James

    2016-09-01

    Bundled or episode payments are among the most heavily emphasized approaches to aligning incentives and promoting care coordination, efficiency, and accountability in health care redesign. Bundled or episode payments price a market basket of services for an entire episode of care with both a clearly defined trigger and termination. Because the radiologist is "ancillary" in many bundles, the specialty is often unaware of the phenomenon. This is likely to change rapidly. Radiology is pivotal in high-prevalence, high-impact care areas such as low back pain and stroke that are focuses of widely used system performance metrics. More important, radiology is central to the diagnosis and management of a wide range of important diagnostic issues in areas such as breast cancer, pulmonary nodules, and incidental findings. Three models of bundled care will probably involve radiology intimately in the near future. Pure radiology bundles might be constructed for breast cancer screening and diagnosis, and these could be priced on the basis of guideline-based best-practice frequencies of care events such as recall and biopsy. Clinical bundles, for example low back pain, could be priced on the basis of optimal imaging frequencies. Finally, pricing of imaging studies might include evidence-based frequencies of follow-up imaging for incidental findings. PMID:27210231

  13. Talin can crosslink actin filaments into both networks and bundles.

    PubMed

    Zhang, J; Robson, R M; Schmidt, J M; Stromer, M H

    1996-01-17

    The talin-actin interaction was examined by using negative staining and cosedimentation assays. At pH 6.4 and low ionic strength, talin extensively crosslinked actin filaments into both networks and bundles. The bundles consist of parallel actin filaments with a center-to-center distance of 13 nm, and talin crossbridges spaced at 36-nm intervals along the bundles. As pH was increased stepwise from 6.4 to 7.3, talin's bundling activity was decreased first, then its networking activity. Qualitatively similar results were obtained at pH 6.4 by increasing ionic strength. Chemical crosslinking indicated talin was present as a dimer from pH 6.4 to 7.3, with or without added KC1. The results show that talin can interact directly with actin filaments by formation of actin filament networks and bundles, with the bundles more sensitive to dissolution by increase in pH or ionic strength. PMID:8561791

  14. An evaluation of the impact of the ventilator care bundle.

    PubMed

    Crunden, Eddie; Boyce, Carolyn; Woodman, Helen; Bray, Barbara

    2005-01-01

    A number of interventions have been shown to improve the outcomes of patients who are invasively ventilated in intensive care units (ICUs). However, significant problems still exist in implementing research findings into clinical practice. The aim of this study was to assess whether the systematic and methodical implementation of evidence-based interventions encapsulated in a care bundle influenced length of ventilation and ICU length of stay (LOS). A ventilator care bundle was introduced within a general ICU and evaluated 1 year later. The care bundle was composed of four protocols that consisted of prophylaxis against peptic ulceration, prophylaxis against deep vein thrombosis, daily cessation of sedation and elevation of the patient's head and chest to at least 30 degrees to the horizontal. Compliance with the bundle was assessed, as was ICU LOS, ICU mortality and ICU/high-dependency unit patient throughput. Mean ICU LOS was reduced from 13-75 [standard deviation (SD) 19.11] days to 8.36 (SD 10.21) days (p<0.05). Mean ventilator days were reduced from 10.8 (SD 15.58) days to 6.1 (SD 8.88) days. Unit patient throughput increased by 30.1% and the number of invasively ventilated patients increased by 39.5%. Care bundles encourage the consistent and systematic application of evidence-based protocols used in particular treatment regimes. Since the introduction of the ventilator care bundle, length of ventilation and ICU LOS have reduced significantly. PMID:16161379

  15. Phototransduction in mouse rods and cones

    PubMed Central

    Fu, Yingbin; Yau, King-Wai

    2010-01-01

    Phototransduction is the process by which light triggers an electrical signal in a photoreceptor cell. Image-forming vision in vertebrates is mediated by two types of photoreceptors: the rods and the cones. In this review, we provide a summary of the success in which the mouse has served as a vertebrate model for studying rod phototransduction, with respect to both the activation and termination steps. Cones are still not as well-understood as rods partly because it is difficult to work with mouse cones due to their scarcity and fragility. The situation may change, however. PMID:17226052

  16. How supercontinents and superoceans affect seafloor roughness.

    PubMed

    Whittaker, Joanne M; Müller, R Dietmar; Roest, Walter R; Wessel, Paul; Smith, Walter H F

    2008-12-18

    Seafloor roughness varies considerably across the world's ocean basins and is fundamental to controlling the circulation and mixing of heat in the ocean and dissipating eddy kinetic energy. Models derived from analyses of active mid-ocean ridges suggest that ocean floor roughness depends on seafloor spreading rates, with rougher basement forming below a half-spreading rate threshold of 30-35 mm yr(-1) (refs 4, 5), as well as on the local interaction of mid-ocean ridges with mantle plumes or cold-spots. Here we present a global analysis of marine gravity-derived roughness, sediment thickness, seafloor isochrons and palaeo-spreading rates of Cretaceous to Cenozoic ridge flanks. Our analysis reveals that, after eliminating effects related to spreading rate and sediment thickness, residual roughness anomalies of 5-20 mGal remain over large swaths of ocean floor. We found that the roughness as a function of palaeo-spreading directions and isochron orientations indicates that most of the observed excess roughness is not related to spreading obliquity, as this effect is restricted to relatively rare occurrences of very high obliquity angles (>45 degrees ). Cretaceous Atlantic ocean floor, formed over mantle previously overlain by the Pangaea supercontinent, displays anomalously low roughness away from mantle plumes and is independent of spreading rates. We attribute this observation to a sub-Pangaean supercontinental mantle temperature anomaly leading to slightly thicker than normal Late Jurassic and Cretaceous Atlantic crust, reduced brittle fracturing and smoother basement relief. In contrast, ocean crust formed above Pacific superswells, probably reflecting metasomatized lithosphere underlain by mantle at only slightly elevated temperatures, is not associated with basement roughness anomalies. These results highlight a fundamental difference in the nature of large-scale mantle upwellings below supercontinents and superoceans, and their impact on oceanic crustal

  17. Initiative learning algorithm based on rough set

    NASA Astrophysics Data System (ADS)

    Wang, Guoyin; He, Xiao

    2003-03-01

    Rough set theory is emerging as a new tool for dealing with fuzzy and uncertain data. In this paper, a theory is developed to express, measure and process uncertain information and uncertain knowledge based on our result about the uncertainty measure of decision tables and decision rule systems. Based on Skowron"s propositional default rule generation algorithm, we develop an initiative learning model with rough set based initiative rule generation algorithm. Simulation results illustrate its efficiency.

  18. Preparation of novel layer-stack hexagonal CdO micro-rods by a pre-oxidation and subsequent evaporation process

    SciTech Connect

    Peng, Kun; Jiang, Pan; Zhu, Jiajun; Zhou, Lingping; Li, Deyi

    2014-12-15

    Graphical abstract: Layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared. - Highlights: • Novel hexagonal layer-stack structure CdO micro-rods were synthesized by a thermal evaporation method. • The pre-oxidation, vapor pressure and substrate nature play a key role on the formation of CdO rods. • The formation mechanism of CdO micro-rods was explained. - Abstract: Novel layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared by pre-oxidizing Cd granules and subsequent thermal oxidation under normal atmospheric pressure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the phase structure and microstructure. The pre-oxidation process, vapor pressure and substrate nature were the key factors for the formation of CdO micro-rods. The diameter of micro-rod and surface rough increased with increasing of thermal evaporation temperature, the length of micro-rod increased with the increasing of evaporation time. The formation of hexagonal layer-stack structure was explained by a vapor–solid mechanism.

  19. Rough surface reconstruction for ultrasonic NDE simulation

    SciTech Connect

    Choi, Wonjae; Shi, Fan; Lowe, Michael J. S.; Skelton, Elizabeth A.; Craster, Richard V.

    2014-02-18

    The reflection of ultrasound from rough surfaces is an important topic for the NDE of safety-critical components, such as pressure-containing components in power stations. The specular reflection from a rough surface of a defect is normally lower than it would be from a flat surface, so it is typical to apply a safety factor in order that justification cases for inspection planning are conservative. The study of the statistics of the rough surfaces that might be expected in candidate defects according to materials and loading, and the reflections from them, can be useful to develop arguments for realistic safety factors. This paper presents a study of real rough crack surfaces that are representative of the potential defects in pressure-containing power plant. Two-dimensional (area) values of the height of the roughness have been measured and their statistics analysed. Then a means to reconstruct model cases with similar statistics, so as to enable the creation of multiple realistic realizations of the surfaces, has been investigated, using random field theory. Rough surfaces are reconstructed, based on a real surface, and results for these two-dimensional descriptions of the original surface have been compared with those from the conventional model based on a one-dimensional correlation coefficient function. In addition, ultrasonic reflections from them are simulated using a finite element method.

  20. Control rod drive hydraulic system

    DOEpatents

    Ose, Richard A.

    1992-01-01

    A hydraulic system for a control rod drive (CRD) includes a variable output-pressure CR pump operable in a charging mode for providing pressurized fluid at a charging pressure, and in a normal mode for providing the pressurized fluid at a purge pressure, less than the charging pressure. Charging and purge lines are disposed in parallel flow between the CRD pump and the CRD. A hydraulic control unit is disposed in flow communication in the charging line and includes a scram accumulator. An isolation valve is provided in the charging line between the CRD pump and the scram accumulator. A controller is operatively connected to the CRD pump and the isolation valve and is effective for opening the isolation valve and operating the CRD pump in a charging mode for charging the scram accumulator, and closing the isolation valve and operating the CRD pump in a normal mode for providing to the CRD through the purge line the pressurized fluid at a purge pressure lower than the charging pressure.

  1. Results of international standard problem No. 36 severe fuel damage experiment of a VVER fuel bundle

    SciTech Connect

    Firnhaber, M.; Yegorova, L.; Brockmeier, U.

    1995-09-01

    International Standard Problems (ISP) organized by the OECD are defined as comparative exercises in which predictions with different computer codes for a given physical problem are compared with each other and with a carefully controlled experimental study. The main goal of ISP is to increase confidence in the validity and accuracy of analytical tools used in assessing the safety of nuclear installations. In addition, it enables the code user to gain experience and to improve his competence. This paper presents the results and assessment of ISP No. 36, which deals with the early core degradation phase during an unmitigated severe LWR accident in a Russian type VVER. Representatives of 17 organizations participated in the ISP using the codes ATHLET-CD, ICARE2, KESS-III, MELCOR, SCDAP/RELAP5 and RAPTA. Some participants performed several calculations with different codes. As experimental basis the severe fuel damage experiment CORA-W2 was selected. The main phenomena investigated are thermal behavior of fuel rods, onset of temperature escalation, material behavior and hydrogen generation. In general, the calculations give the right tendency of the experimental results for the thermal behavior, the hydrogen generation and, partly, for the material behavior. However, some calculations deviate in important quantities - e.g. some material behavior data - showing remarkable discrepancies between each other and from the experiments. The temperature history of the bundle up to the beginning of significant oxidation was calculated quite well. Deviations seem to be related to the overall heat balance. Since the material behavior of the bundle is to a great extent influenced by the cladding failure criteria a more realistic cladding failure model should be developed at least for the detailed, mechanistic codes. Regarding the material behavior and flow blockage some models for the material interaction as well as for relocation and refreezing requires further improvement.

  2. Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Bentz, Daniel N.; Betush, William; Jackson, Kenneth A.

    2003-01-01

    In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (kMC) simulation with diffusion by pair exchange only in the liquid phase. Entropies of fusion are first chosen to fit the surface roughness of the pure materials, and the bond energies are derived from the equilibrium phase diagram, by treating the solid and liquid as regular and ideal solutions respectively. A simple cubic lattice oriented in the {100} direction is used. Growth of the rods is initiated from columns of pure B material embedded in an A matrix, arranged in a close packed array with semi-periodic boundary conditions. The simulation cells typically have dimensions of 50 by 87 by 200 unit cells. Steady state growth is compliant with the Jackson-Hunt model. In the kMC simulations, using the spin-one Ising model, growth of each phase is faceted or nonfaceted phases depending on the entropy of fusion. There have been many studies of the surface roughening transition in single component systems, but none for binary alloy systems. The location of the surface roughening transition for the phases of a eutectic alloy determines whether the eutectic morphology will be regular or irregular. We have conducted a study of surface roughness on the spin-one Ising Model with diffusion using kMC. The surface roughness was found to scale with the melting temperature of the alloy as given by the liquidus line on the equilibrium phase diagram. The density of missing lateral bonds at the surface was used as a measure of surface roughness.

  3. Combustor having mixing tube bundle with baffle arrangement for directing fuel

    DOEpatents

    Hughes, Michael John; McConnaughhay, Johnie Franklin

    2016-08-23

    A combustor includes a tube bundle that extends radially across at least a portion of the combustor. The tube bundle includes an upstream surface axially separated from a downstream surface, and a plurality of tubes extend from the upstream surface through the downstream surface to provide fluid communication through the tube bundle. A barrier extends radially inside the tube bundle between the upstream and downstream surfaces, and a baffle extends axially inside the tube bundle between the upstream surface and the barrier.

  4. Control rod for a nuclear reactor

    DOEpatents

    Roman, Walter G.; Sutton, Jr., Harry G.

    1979-01-01

    A control rod assembly for a nuclear reactor is disclosed having a remotely disengageable coupling between the control rod and the control rod drive shaft. The coupling is actuated by first lowering then raising the drive shaft. The described motion causes axial repositioning of a pin in a grooved rotatable cylinder, each being attached to different parts of the drive shaft which are axially movable relative to each other. In one embodiment, the relative axial motion of the parts of the drive shaft is used either to couple or to uncouple the connection by forcing resilient members attached to the drive shaft into or out of shouldered engagement, respectively, with an indentation formed in the control rod.

  5. Impact of AD995 alumina rods

    SciTech Connect

    Chhabildas, L.C.; Furnish, M.D.; Reinhart, W.D.; Grady, D.E.

    1997-10-01

    Gas guns and velocity interferometric techniques have been used to determine the loading behavior of an AD995 alumina rod 19 mm in diameter by 75 mm and 150 mm long, respectively. Graded-density materials were used to impact both bare and sleeved alumina rods while the velocity interferometer was used to monitor the axial-velocity of the free end of the rods. Results of these experiments demonstrate that (1) a time-dependent stress pulse generated during impact allows an efficient transition from the initial uniaxial strain loading to a uniaxial stress state as the stress pulse propagates through the rod, and (2) the intermediate loading rates obtained in this configuration lie between split Hopkinson bar and shock-loading techniques.

  6. Double-clad nuclear fuel safety rod

    DOEpatents

    McCarthy, William H.; Atcheson, Donald B.; Vaidyanathan, Swaminathan

    1984-01-01

    A device for shutting down a nuclear reactor during an undercooling or overpower event, whether or not the reactor's scram system operates properly. This is accomplished by double-clad fuel safety rods positioned at various locations throughout the reactor core, wherein melting of a secondary internal cladding of the rod allows the fuel column therein to shift from the reactor core to place the reactor in a subcritical condition.

  7. Fault slip distribution and fault roughness

    NASA Astrophysics Data System (ADS)

    Candela, Thibault; Renard, François; Schmittbuhl, Jean; Bouchon, Michel; Brodsky, Emily E.

    2011-11-01

    We present analysis of the spatial correlations of seismological slip maps and fault topography roughness, illuminating their identical self-affine exponent. Though the complexity of the coseismic spatial slip distribution can be intuitively associated with geometrical or stress heterogeneities along the fault surface, this has never been demonstrated. Based on new measurements of fault surface topography and on statistical analyses of kinematic inversions of slip maps, we propose a model, which quantitatively characterizes the link between slip distribution and fault surface roughness. Our approach can be divided into two complementary steps: (i) Using a numerical computation, we estimate the influence of fault roughness on the frictional strength (pre-stress). We model a fault as a rough interface where elastic asperities are squeezed. The Hurst exponent ?, characterizing the self-affinity of the frictional strength field, approaches ?, where ? is the roughness exponent of the fault surface in the direction of slip. (ii) Using a quasi-static model of fault propagation, which includes the effect of long-range elastic interactions and spatial correlations in the frictional strength, the spatial slip correlation is observed to scale as ?, where ? represents the Hurst exponent of the slip distribution. Under the assumption that the origin of the spatial fluctuations in frictional strength along faults is the elastic squeeze of fault asperities, we show that self-affine geometrical properties of fault surface roughness control slip correlations and that ?. Given that ? for a wide range of faults (various accumulated displacement, host rock and slip movement), we predict that ?. Even if our quasi-static fault model is more relevant for creeping faults, the spatial slip correlations observed are consistent with those of seismological slip maps. A consequence is that the self-affinity property of slip roughness may be explained by fault geometry without considering

  8. The work budget of rough faults

    NASA Astrophysics Data System (ADS)

    Newman, Patrick J.; Ashley Griffith, W.

    2014-12-01

    Faults in nature have measurable roughness at many scales and are not planar as generally idealized. We utilize the boundary element method to model the geomechanical response of synthetic rough faults in an isotropic, linear elastic continuum to external tectonic loading in terms of the work budget. Faults are generated with known fractal roughness parameters, including the root mean square slope (β), a measure of roughness amplitude, and the Hurst exponent (H), a measure of geometric self-similarity. Energy within the fault models is partitioned into external work (Wext), internal elastic strain energy (Wint), gravitational work (Wgrav), frictional work (Wfric), and seismic energy (Wseis). Results confirm that Wext, or work done on the external model boundaries, is smallest for a perfectly planar fault, and steadily increases with increasing β. This pattern is also observed in Wint, the energy expended in deforming the host rock. The opposite is true for gravitational work, or work done against gravity in uplifting host rock, as well as with frictional work, or energy dissipated with frictional slip on the fault, and Wseis, or seismic energy released during slip events. Effects of variation in H are not as large as for β, but Wgrav, Wfric, and Wseis increase with increasing H, with Wint and Wext decreasing across the same range. Remarkably, however, for a narrow range of roughness amplitudes which are commonly observed along natural faults, the total work of the system remains approximately constant, while slightly larger than the total work of a planar fault. Faults evolve toward the most mechanically efficient configuration; therefore we argue that this range of roughness amplitudes may represent an energy barrier, preventing faults from removing asperities and evolving to smooth, planar discontinuities. A similar conclusion is drawn from simulations at relatively shallow depths, with results showing that shallower faults have larger energy barriers, and can

  9. Measurements of control rod efficiency in RBMK critical assembly upon dropping of the rods

    SciTech Connect

    Zhitarev, V. E. Kachanov, V. M.; Sergevnin, A. Yu.; Lebedev, G. V.

    2014-12-15

    The efficiency of control rods in the RBMK critical assembly was measured in the case where one manual-control rod (MCR) is dropped from a steady critical state, and several other MCRs were additionally dropped after 44 s. The measured number of neutrons in the assembly during and after dropping of the rods was used to calculate the efficiency values of the rods by solution of the system of point kinetics equations. A series of methods of the initial data treatment for determination of the desired values of reactivity without the calculated corrections were used.

  10. Epigenomic landscapes of retinal rods and cones

    PubMed Central

    Mo, Alisa; Luo, Chongyuan; Davis, Fred P; Mukamel, Eran A; Henry, Gilbert L; Nery, Joseph R; Urich, Mark A; Picard, Serge; Lister, Ryan; Eddy, Sean R; Beer, Michael A; Ecker, Joseph R; Nathans, Jeremy

    2016-01-01

    Rod and cone photoreceptors are highly similar in many respects but they have important functional and molecular differences. Here, we investigate genome-wide patterns of DNA methylation and chromatin accessibility in mouse rods and cones and correlate differences in these features with gene expression, histone marks, transcription factor binding, and DNA sequence motifs. Loss of NR2E3 in rods shifts their epigenomes to a more cone-like state. The data further reveal wide differences in DNA methylation between retinal photoreceptors and brain neurons. Surprisingly, we also find a substantial fraction of DNA hypo-methylated regions in adult rods that are not in active chromatin. Many of these regions exhibit hallmarks of regulatory regions that were active earlier in neuronal development, suggesting that these regions could remain undermethylated due to the highly compact chromatin in mature rods. This work defines the epigenomic landscapes of rods and cones, revealing features relevant to photoreceptor development and function. DOI: http://dx.doi.org/10.7554/eLife.11613.001 PMID:26949250

  11. Close packing of rods on spherical surfaces

    NASA Astrophysics Data System (ADS)

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-01

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets.

  12. Close packing of rods on spherical surfaces.

    PubMed

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-28

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets. PMID:27131565

  13. High-throughput rod-induced electrospinning

    NASA Astrophysics Data System (ADS)

    Wu, Dezhi; Xiao, Zhiming; Teh, Kwok Siong; Han, Zhibin; Luo, Guoxi; Shi, Chuan; Sun, Daoheng; Zhao, Jinbao; Lin, Liwei

    2016-09-01

    A high throughput electrospinning process, directly from flat polymer solution surfaces induced by a moving insulating rod, has been proposed and demonstrated. Different rods made of either phenolic resin or paper with a diameter of 1–3 cm and a resistance of about 100–500 MΩ, has been successfully utilized in the process. The rod is placed approximately 10 mm above the flat polymer solution surface with a moving speed of 0.005–0.4 m s‑1 this causes the solution to generate multiple liquid jets under an applied voltage of 15–60 kV for the tip-less electrospinning process. The local electric field induced by the rod can boost electrohydrodynamic instability in order to generate Taylor cones and liquid jets. Experimentally, it is found that a large rod diameter and a small solution-to-rod distance can enhance the local electrical field to reduce the magnitude of the applied voltage. In the prototype setup with poly (ethylene oxide) polymer solution, an area of 5 cm  ×  10 cm and under an applied voltage of 60 kV, the maximum throughput of nanofibers is recorded to be approximately144 g m‑2 h‑1.

  14. Controlled synthesis of ZnO from nanospheres to micro-rods and its gas sensing studies.

    PubMed

    Navale, Shalaka C; Gosavi, S W; Mulla, I S

    2008-06-15

    1D ZnO rods are synthesized using less explored hydrazine method. Here we find, besides being combustible hydrazine can also be used as a structure-directing agent. The ratio of zinc nitrate (ZN) to hydrazine is found to control the morphology of ZnO. At lower concentration of ZN as compared with hydrazine the morphology of ZnO is found to be spherical. As we increase the hydrazine content the morphology changes from spherical (diameter approximately 100 nm) to the elongated structures including shapes like Y, T as well dumbbell (diameter approximately 40 nm and length approximately 150 nm). Interestingly for more than 50% of hydrazine ZnO micro-rods are formed. Such rods are of diameter approximately 120 nm having length of about 1 microm for ZN to hydrazine ratio of 1:9, isolated as well as bundle of rods are seen in scanning electron microscopy (SEM). The X-ray diffraction (XRD) reveals the phase formation with average particle size of 37 nm as calculated using Scherrer's formula. The high-resolution transmission electron microscopy (HRTEM) is also done to confirm the d-spacing in ZnO. Gas sensing study for these samples shows high efficiency and selectivity towards LPG at all operating temperatures. Photoluminescence (PL) study for these samples is performed at room temperature to find potential application as photoelectric material. PMID:18585218

  15. Verification of the FBR fuel bundle-duct interaction analysis code BAMBOO by the out-of-pile bundle compression test with large diameter pins

    NASA Astrophysics Data System (ADS)

    Uwaba, Tomoyuki; Ito, Masahiro; Nemoto, Junichi; Ichikawa, Shoichi; Katsuyama, Kozo

    2014-09-01

    The BAMBOO computer code was verified by results for the out-of-pile bundle compression test with large diameter pin bundle deformation under the bundle-duct interaction (BDI) condition. The pin diameters of the examined test bundles were 8.5 mm and 10.4 mm, which are targeted as preliminary fuel pin diameters for the upgraded core of the prototype fast breeder reactor (FBR) and for demonstration and commercial FBRs studied in the FaCT project. In the bundle compression test, bundle cross-sectional views were obtained from X-ray computer tomography (CT) images and local parameters of bundle deformation such as pin-to-duct and pin-to-pin clearances were measured by CT image analyses. In the verification, calculation results of bundle deformation obtained by the BAMBOO code analyses were compared with the experimental results from the CT image analyses. The comparison showed that the BAMBOO code reasonably predicts deformation of large diameter pin bundles under the BDI condition by assuming that pin bowing and cladding oval distortion are the major deformation mechanisms, the same as in the case of small diameter pin bundles. In addition, the BAMBOO analysis results confirmed that cladding oval distortion effectively suppresses BDI in large diameter pin bundles as well as in small diameter pin bundles.

  16. 49 CFR 230.93 - Pistons and piston rods.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Pistons and piston rods. 230.93 Section 230.93... Tenders Driving Gear § 230.93 Pistons and piston rods. (a) Maintenance and testing. Pistons and piston rods shall be maintained in safe and suitable condition for service. Piston rods shall be inspected...

  17. International symposium on fuel rod simulators: development and application

    SciTech Connect

    McCulloch, R.W.

    1981-05-01

    Separate abstracts are included for each of the papers presented concerning fuel rod simulator operation and performance; simulator design and evaluation; clad heated fuel rod simulators and fuel rod simulators for cladding investigations; fuel rod simulator components and inspection; and simulator analytical modeling. Ten papers have previously been input to the Energy Data Base.

  18. Mechanical performance of fiberglass sucker-rod strings

    SciTech Connect

    Tripp, H.A.

    1988-08-01

    The natural frequencies of fiberglass sucker-rod strings can be calculated by treating the rod strings as modified spring/mass vibration systems. The ratio of the pumping-unit operating speed to the rod-string natural frequency can then be used as a basis for understanding fiberglass-rod performance and for predicting downhole pump stroke lengths.

  19. Genetic Analysis of Rough Sheath1 Developmental Mutants of Maize

    PubMed Central

    Becraft, P. W.; Freeling, M.

    1994-01-01

    Maize Rough sheath1 (Rs1) mutants are dominant and cause a proliferation of sheath-like tissue at the base of the blade and throughout the ligular region. They also cause ligule displacement, a chaotic pattern of vasculature and abnormal cellular structure of vascular bundles. The affected region of Rs1-O leaves displays genetic and morphological attributes of both sheath and auricle, suggesting an overlap of these genetic programs. The rs1 locus maps approximately 26 map units distal to opaque2 (o2) on chromosome 7S, defining a new distal-most locus on the genetic map. Three mutant alleles, Rs1-O, Rs1-1025 and Rs1-Z, all display similar phenotypes. The mutations are completely dominant and the Rs1-O phenotype is not affected by dosage of the chromosome arm carrying the rs1(+) allele, indicating that these alleles are neomorphic. Analysis of genetic mosaics showed that the Rs1-O phenotype is non-cell-autonomous, suggesting that intercellular signals convey the phenotype. Rs1 mutant phenotypes are affected by modifiers present in particular genetic backgrounds. An enhancer of Rs1-O was identified; segregation data imply a single recessive gene, ers1. Rs1 mutants were also found to enhance the expression of unlinked rs2 and Rs4 mutants, suggesting that these mutations affect similar developmental processes. We discuss the phenotypic and genetic similarities between Rs1 and Knotted1 (Kn1) mutants that led to the identification of rs1 as a kn1-like homeobox gene (unpublished data). PMID:8138166

  20. Hypersonic Viscous Flow Over Large Roughness Elements

    NASA Technical Reports Server (NTRS)

    Chang, Chau-Lyan; Choudhari, Meelan M.

    2009-01-01

    Viscous flow over discrete or distributed surface roughness has great implications for hypersonic flight due to aerothermodynamic considerations related to laminar-turbulent transition. Current prediction capability is greatly hampered by the limited knowledge base for such flows. To help fill that gap, numerical computations are used to investigate the intricate flow physics involved. An unstructured mesh, compressible Navier-Stokes code based on the space-time conservation element, solution element (CESE) method is used to perform time-accurate Navier-Stokes calculations for two roughness shapes investigated in wind tunnel experiments at NASA Langley Research Center. It was found through 2D parametric study that at subcritical Reynolds numbers, spontaneous absolute instability accompanying by sustained vortex shedding downstream of the roughness is likely to take place at subsonic free-stream conditions. On the other hand, convective instability may be the dominant mechanism for supersonic boundary layers. Three-dimensional calculations for both a rectangular and a cylindrical roughness element at post-shock Mach numbers of 4.1 and 6.5 also confirm that no self-sustained vortex generation from the top face of the roughness is observed, despite the presence of flow unsteadiness for the smaller post-shock Mach number case.

  1. Correlation of Windspeed and Antarctic Surface Roughness

    NASA Astrophysics Data System (ADS)

    Stockham, Mark; Anita Collaboration

    2015-04-01

    When electromagnetic waves interact with a media interface the transmitted and reflected portions of the incoming wave depend on the incident angle of the wave and wavelength (as well as the material properties of the media). The roughness of the surface of Antarctica affects the radio frequency signals received by airborne experiments, such as the balloon-borne experiment ANITA (ANtarctic Impulsive Transient Antenna) which observes the reflected radio waves from cosmic ray-induced extensive air showers (EAS). Roughness of a given scale can cause decoherence of the reflected signal and is an important effect to understand when estimating the amplitude of the incoming wave based on the reflected wave. It is challenging to get a survey of surface roughness over many of the areas that these experiments are likely to pass over. Correlating historical wind speed records with statistical roughness as observed by the backscatter of satellite [Rémy F, Parouty S. Remote Sensing. 2009] and airborne experiments operating at different frequencies can possibly be used to predict time-dependent surface roughness with surface wind speed as the input. These correlations will be presented for a variety of areas on the Antarctic ice shelf. NASA Grant NNX11AC47G.

  2. Interfacial roughness in ceramic matrix composites

    SciTech Connect

    Jero, P.D.; Parthasarathy, T.A.; Kerans, R.J.

    1992-08-01

    Recent work using push-out and push-back tests has shown that interfacial roughness contributes substantially to the sliding friction in at least some ceramic matrix composites (CMC's). Other work examining frictional heating of CMC's during cyclic fatigue has shown the important role that interfacial friction plays, and further that the interface is degraded upon extended cycling. From this it is apparent that interfacial roughness may play a key role in determining composite behavior. Although the observation of a seating drop during fiber push-back gives some information about the amplitude and spatial extent of the interfacial roughness, actual measurement of the roughness has proven difficult due to its extremely fine scale. In the present work, a laser interferometer has been used to examine the roughness of composite interfaces (both fiber and matrix) as well as virgin fibers. In addition, long range (mm scale) push-out tests have been followed by interferometric characterization to examine the severity and rate of interfacial degradation associated with fiber sliding. 4 refs.

  3. Nuclear reactor remote disconnect control rod coupling indicator

    DOEpatents

    Vuckovich, Michael

    1977-01-01

    A coupling indicator for use with nuclear reactor control rod assemblies which have remotely disengageable couplings between the control rod and the control rod drive shaft. The coupling indicator indicates whether the control rod and the control rod drive shaft are engaged or disengaged. A resistive network, utilizing magnetic reed switches, senses the position of the control rod drive mechanism lead screw and the control rod position indicating tube, and the relative position of these two elements with respect to each other is compared to determine whether the coupling is engaged or disengaged.

  4. External Verification of the Bundle Adjustment in Photogrammetric Software Using the Damped Bundle Adjustment Toolbox

    NASA Astrophysics Data System (ADS)

    Börlin, Niclas; Grussenmeyer, Pierre

    2016-06-01

    The aim of this paper is to investigate whether the Matlab-based Damped Bundle Adjustment Toolbox (DBAT) can be used to provide independent verification of the BA computation of two popular software—PhotoModeler (PM) and PhotoScan (PS). For frame camera data sets with lens distortion, DBAT is able to reprocess and replicate subsets of PM results with high accuracy. For lens-distortion-free data sets, DBAT can furthermore provide comparative results between PM and PS. Data sets for the discussed projects are available from the authors. The use of an external verification tool such as DBAT will enable users to get an independent verification of the computations of their software. In addition, DBAT can provide computation of quality parameters such as estimated standard deviations, correlation between parameters, etc., something that should be part of best practice for any photogrammetric software. Finally, as the code is free and open-source, users can add computations of their own.

  5. Microstructure, porosity and roughness of RF sputtered oxide thin films: Characterization and modelization

    NASA Astrophysics Data System (ADS)

    Oudrhiri-Hassani, Fahd; Presmanes, Lionel; Barnabé, Antoine; Tailhades, Philippe

    2008-07-01

    Spinel CoMnFeO 4 thin films are stable materials useful to study the influence of radio-frequency (RF) sputtering experimental conditions on the microstructure of oxide films. It has been demonstrated by various techniques such as electronic and atomic force microscopy (AFM), gas adsorption techniques and ellipsometry, that films prepared with 0.5 Pa sputtering argon pressure and 5 cm target-substrate distance are very dense. On the other hand, the samples obtained under higher pressure and/or longer distances are microporous with a mean pore size generally lower than 2 nm. The specific surface areas of such films reach about 75 m 2/g. According to the simple model proposed, the films are made of three layers. From the bottom to the top of the film, the first one at the interface with the substrate is 100% dense. The second layer is made of cylindrical rods set up according to a compact plane. Its porosity is due to the lattice interstices. Hemispheric domes covering each rod make up the third layer, which displays a degree of roughness related to the shape and the hexagonal arrangement of the domes. The surface enhancement factor (SEF), the porosity and roughness, calculated from the model, are in corroboration with the experimental values. The porosity factor is however slightly underestimated by the model for very porous samples.

  6. On roughness-induced transition - Facts, views, and speculations

    NASA Technical Reports Server (NTRS)

    Morkovin, Mark V.

    1990-01-01

    Roughness is considered as a steady passive device, and it is shown that roughness-induced separation is specifically sensitive to unsteady environmental forcing. The two-dimensional isolated roughness causing local upstream and downstream separations is considered, along with flows associated with the two-dimensional roughness and their relevance to the problem of distributed roughness. The difference between the two-dimensional isolated roughness and a three-dimensional isolated roughness at all Reynolds numbers is underlined, and the mechanisms and parameter conditions of a sudden breakdown of hairpin eddies are discussed, as well as flows over distributed roughness.

  7. Time-dependent fiber bundles with local load sharing.

    PubMed

    Newman, W I; Phoenix, S L

    2001-02-01

    Fiber bundle models, where fibers have random lifetimes depending on their load histories, are useful tools in explaining time-dependent failure in heterogeneous materials. Such models shed light on diverse phenomena such as fatigue in structural materials and earthquakes in geophysical settings. Various asymptotic and approximate theories have been developed for bundles with various geometries and fiber load-sharing mechanisms, but numerical verification has been hampered by severe computational demands in larger bundles. To gain insight at large size scales, interest has returned to idealized fiber bundle models in 1D. Such simplified models typically assume either equal load sharing (ELS) among survivors, or local load sharing (LLS) where a failed fiber redistributes its load onto its two nearest flanking survivors. Such models can often be solved exactly or asymptotically in increasing bundle size, N, yet still capture the essence of failure in real materials. The present work focuses on 1D bundles under LLS. As in previous works, a fiber has failure rate following a power law in its load level with breakdown exponent rho. Surviving fibers under fixed loads have remaining lifetimes that are independent and exponentially distributed. We develop both new asymptotic theories and new computational algorithms that greatly increase the bundle sizes that can be treated in large replications (e.g., one million fibers in thousands of realizations). In particular we develop an algorithm that adapts several concepts and methods that are well-known among computer scientists, but relatively unknown among physicists, to dramatically increase the computational speed with no attendant loss of accuracy. We consider various regimes of rho that yield drastically different behavior as N increases. For 1/2< or =rho< or =1, ELS and LLS have remarkably similar behavior (they have identical lifetime distributions at rho=1) with approximate Gaussian bundle lifetime statistics and a

  8. CRYPTOCHROME2 in Vascular Bundles Regulates Flowering in Arabidopsis

    PubMed Central

    Endo, Motomu; Mochizuki, Nobuyoshi; Suzuki, Tomomi; Nagatani, Akira

    2007-01-01

    Plants make full use of light signals to determine the timing of flowering. In Arabidopsis thaliana, a blue/UV-A photoreceptor, CRYPTOCHROME 2 (cry2), and a red/far-red photoreceptor, PHYTOCHROME B (phyB), are two major photoreceptors that control flowering. The light stimuli for the regulation of flowering are perceived by leaves. We have recently shown that phyB expression in mesophyll but not in vascular bundles suppresses the expression of a key flowering regulator, FLOWERING LOCUS T (FT), in vascular bundles. In this study, we asked where in the leaf cry2 perceives light stimuli to regulate flowering. To answer this question, we established transgenic Arabidopsis lines in which the cry2–green fluorescent protein (GFP) fusion was expressed under the control of organ/tissue-specific promoters in a cry2-deficient mutant background. Analysis of these lines revealed that expression of cry2-GFP in vascular bundles, but not in epidermis or mesophyll, rescued the late flowering phenotype. We further confirmed that cry2-GFP expressed in vascular bundles increased FT expression only in vascular bundles. Hence, in striking contrast with phyB, cry2 most likely regulates FT expression in a cell-autonomous manner. PMID:17259260

  9. Reaction–diffusion model of hair-bundle morphogenesis

    PubMed Central

    Jacobo, Adrian; Hudspeth, A. J.

    2014-01-01

    The hair bundle, an apical specialization of the hair cell composed of several rows of regularly organized stereocilia and a kinocilium, is essential for mechanotransduction in the ear. Its precise organization allows the hair bundle to convert mechanical stimuli to electrical signals; mutations that alter the bundle’s morphology often cause deafness. However, little is known about the proteins involved in the process of morphogenesis and how the structure of the bundle arises through interactions between these molecules. We present a mathematical model based on simple reaction–diffusion mechanisms that can reproduce the shape and organization of the hair bundle. This model suggests that the boundary of the cell and the kinocilium act as signaling centers that establish the bundle’s shape. The interaction of two proteins forms a hexagonal Turing pattern—a periodic modulation of the concentrations of the morphogens, sustained by local activation and long-range inhibition of the reactants—that sets a blueprint for the location of the stereocilia. Finally we use this model to predict how different alterations to the system might impact the shape and organization of the hair bundle. PMID:25313064

  10. Hierarchical streamline bundles for visualizing 2D flow fields.

    SciTech Connect

    Shene, Ching-Kuang; Wang, Chaoli; Yu, Hongfeng; Chen, Jacqueline H.

    2010-08-01

    We present hierarchical streamline bundles, a new approach to simplifying and visualizing 2D flow fields. Our method first densely seeds a flow field and produces a large number of streamlines that capture important flow features such as critical points. Then, we group spatially neighboring and geometrically similar streamlines to construct a hierarchy from which we extract streamline bundles at different levels of detail. Streamline bundles highlight multiscale flow features and patterns through a clustered yet non-cluttered display. This selective visualization strategy effectively accentuates visual foci and therefore is able to convey the desired insight into the flow fields. The hierarchical streamline bundles we have introduced offer a new way to characterize and visualize the flow structure and patterns in multiscale fashion. Streamline bundles highlight critical points clearly and concisely. Exploring the hierarchy allows a complete visualization of important flow features. Thanks to selective streamline display and flexible LOD refinement, our multiresolution technique is scalable and is promising for viewing large and complex flow fields. In the future, we would like to seek a cost-effective way to generate streamlines without enforcing the dense seeding condition. We will also extend this approach to handle real-world 3D complex flow fields.

  11. Geometric Frustration Selects Morphology in Chiral Filament Bundles

    NASA Astrophysics Data System (ADS)

    Hall, Douglas; Bruss, Isaac; Barone, Justin; Grason, Gregory

    Assemblies of twisted filaments appear in a range of biological contexts, from extracellular filament bundles to amyloid fibrils. Owing to numerous distinctions in molecular structures and interactions underlying these diverse assemblies, a framework to predict and classify the basic mechanisms of structure formation in twisted filament assemblies is still lacking. In this study, we model how the size and shape of self-assembled fibers are controlled by competition between the elastic costs of inter-filament frustration, bending deformation of filaments and bundle surface energy. Exploiting a geometric mapping between inter-filament packing in twisted bundles and packing on positively-curved 2D surfaces, we show that the anisotropy of the bundle cross-section is determined by a single parameter describing the competition between elastic and bending costs. We compare the continuum model's predictions for stability of cylindrical and tape-like twisted morphologies to numerical simulations of cohesive filament bundles and observations of micron-scale amyloid fibers assembled from hydrolyzed protein fragments. Nsf (CAREER) DMR-0955760.

  12. Variable recruitment in bundles of miniature pneumatic artificial muscles.

    PubMed

    DeLaHunt, Sylvie A; Pillsbury, Thomas E; Wereley, Norman M

    2016-01-01

    The natural compliance and force generation properties of pneumatic artificial muscles (PAMs) allow them to operate like human muscles in anthropomorphic robotic manipulators. Traditionally, manipulators use a single PAM or multiple PAMs actuated in unison in place of a human muscle. However, these standard manipulators can experience significant efficiency losses when operated outside their target performance ranges at low actuation pressures. This study considers the application of a variable recruitment control strategy to a parallel bundle of miniature PAMs as an attempt to mimic the selective recruitment of motor units in a human muscle. Bundles of miniature PAMs are experimentally characterized, their actuation behavior is modeled, and the efficiency gains and losses associated with the application of a variable recruitment control strategy are assessed. This bio-inspired control strategy allows muscle bundles to operate the fewest miniature PAMs necessary to achieve a desired performance objective, improving the muscle bundle's operating efficiency over larger ranges of force generation and displacement. The study also highlights the need for improved PAM fabrication techniques to facilitate the production of identical miniature PAMs for inclusion in muscle bundles. PMID:27623216

  13. Hair-bundle friction from transduction channels' gating forces

    NASA Astrophysics Data System (ADS)

    Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

    2015-12-01

    Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. We have shown recently that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle and thus provide a major source of damping [2]. We develop here a physical theory of passive hair-bundle mechanics that explains the origin of channel friction. We show that channel friction can be understood quantitatively by coupling the dynamics of the conformational change associated with channel gating to tip-link tension. As a result, varying channel properties affects friction, with faster channels producing smaller friction. The analysis emphasizes the dual role of transduction channels' gating forces, which affect both hair-bundle stiffness and drag. Friction originating from gating of ion channels is a general concept that is relevant to all mechanosensitive channels.

  14. Thermal imaging through infrared fiber/waveguides bundles

    NASA Astrophysics Data System (ADS)

    Gannot, Israel; Goren, Alon; Rave, Eran; Katzir, Abraham; Gopal, Veena; Revezin, Gregory; Harrington, James A.

    2004-06-01

    Trans-endoscopic Infrared Imaging (IRI) relates the possibility to conduct IRI diagnosis of internal body surfaces under minimal invasiveness. It may also be utilized to control and to optimize the thermal interactions and the potential side effects during Minimally Invasive Surgeries (MIS). However, transferring the thermal images transendoscopically requires the usage of IR imaging bundles, which are neither yet mature nor commercially available. In our setup we have used two basic types of recently-developed imaging bundles: Ag/AgI-coated Hollow Glass Waveguide (HGW) bundles and Silver Halide (AgClBr) core-clad fiber bundles. The optical setup system was consisted of IR optics (e.g. ZnSe lenses, reflective objectives) and a thermal IR camera. We have succeeded to image objects through the bundles, such as various shapes of electrically heated wires, ex-vivo biological phantoms (samples of porcine stomach) and in-vivo phantom models (mice) irradiated by CO2 laser. Measurements were conducted for both - static and dynamic object states.

  15. The geological interpretation of photometric surface roughness

    NASA Technical Reports Server (NTRS)

    Helfenstein, Paul

    1988-01-01

    A computer-generated km-scale relief map, whose topographic facets on scales of less than a few m are assumed to have smooth particulate surfaces, is the basis of the present investigation of the relationship between photometrically-derived values of Hapke's (1984) roughness parameter theta and topographic scale. The addition of m-km scale-range relief to the otherwise smooth surface alters integral photometric behavior in a way that is consistent with Hapke's equation; the roughness characterized by theta is an integral property over all scales up to the resolution limit of the photometric data used in its determination. With sufficient phase angle coverage, theta can distinguish terrains with very different integral roughnesses.

  16. Surface roughness effects on equilibrium temperature.

    NASA Technical Reports Server (NTRS)

    Houchens, A. F.; Hering, R. G.

    1972-01-01

    An analysis is presented for evaluation of equilibrium temperature distribution on radiatively adiabatic, adjoint planes which are uniformly irradiated by a collimated solar flux. The analysis employs a semigrey spectral model. Radiation properties for surface emitted radiation are obtained from the expressions of electromagnetic theory for smooth surfaces. Rough surface properties for solar radiation are given by the Beckmann bidirectional reflectance model. Numerical solutions to the governing equations yield equilibrium temperature distributions for a range of the influencing parameters. Surface roughness has little influence on equilibrium temperature for materials with high values for solar absorptance. However, for low or intermediate values of solar absorptance, roughness effects on the spatial distribution of reflected solar radiation can significantly alter equilibrium temperature particularly at surface elements where radiant interaction is small.

  17. Discrete Roughness Transition for Hypersonic Flight Vehicles

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Horvath, Thomas J.

    2007-01-01

    The importance of discrete roughness and the correlations developed to predict the onset of boundary layer transition on hypersonic flight vehicles are discussed. The paper is organized by hypersonic vehicle applications characterized in a general sense by the boundary layer: slender with hypersonic conditions at the edge of the boundary layer, moderately blunt with supersonic, and blunt with subsonic. This paper is intended to be a review of recent discrete roughness transition work completed at NASA Langley Research Center in support of agency flight test programs. First, a review is provided of discrete roughness wind tunnel data and the resulting correlations that were developed. Then, results obtained from flight vehicles, in particular the recently flown Hyper-X and Shuttle missions, are discussed and compared to the ground-based correlations.

  18. Wetting on rough self-affine surfaces

    NASA Astrophysics Data System (ADS)

    Palasantzas, George

    1995-05-01

    In this paper, we present a general investigation of the effective potential for complete wetting on self-affine rough surfaces. The roughness effect is investigated by means of the height-height correlation model in Fourier space ~(1+aξ2q2)-1-H. The parameters H and ξ are, respectively, the roughness exponent and the substrate in-plane correlation length. It is observed that the effect of H on the free interface profile is significant for ξ>ξ) regime is characterized by a power-law scaling ~Y-2.

  19. Photovoltage of Rods and Cones in the Macaque Retina

    NASA Astrophysics Data System (ADS)

    Schneeweis, David M.; Schnapf, Julie L.

    1995-05-01

    The kinetics, gain, and reliability of light responses of rod and cone photoreceptors are important determinants of overall visual sensitivity. In voltage recordings from photoreceptors in an intact primate retina, rods were found to be functionally isolated from each other, unlike the tightly coupled rods of cold-blooded vertebrates. Cones were observed to receive excitatory input from rods, which indicates that the cone pathway also processes rod signals. This input might be expected to degrade the spatial resolution of mesopic vision.

  20. Regulatory perspective on incomplete control rod insertions

    SciTech Connect

    Chatterton, M.

    1997-01-01

    The incomplete control rod insertions experienced at South Texas Unit 1 and Wolf Creek are of safety concern to the NRC staff because they represent potential precursors to loss of shutdown margin. Even before it was determined if these events were caused by the control rods or by the fuel there was an apparent correlation of the problem with high burnup fuel. It was determined that there was also a correlation between high burnup and high drag forces as well as with rod drop time histories and lack of rod recoil. The NRC staff initial actions were aimed at getting a perspective on the magnitude of the problem as far as the number of plants and the amount of fuel that could be involved, as well as the safety significance in terms of shutdown margin. As tests have been performed and data has been analyzed the focus has shifted more toward understanding the problem and the ways to eliminate it. At this time the staff`s understanding of the phenomena is that it was a combination of factors including burnup, power history and temperature. The problem appears to be very sensitive to these factors, the interaction of which is not clearly understood. The model developed by Westinghouse provides a possible explanation but there is not sufficient data to establish confidence levels and sensitivity studies involving the key parameters have not been done. While several fixes to the problem have been discussed, no definitive fixes have been proposed. Without complete understanding of the phenomena, or fixes that clearly eliminate the problem the safety concern remains. The safety significance depends on the amount of shutdown margin lost due to incomplete insertion of the control rods. Were the control rods to stick high in the core, the reactor could not be shutdown by the control rods and other means such as emergency boration would be required.

  1. ROUGHNESS LENGTHS FOR THE SAVANNAH RIVER SITE

    SciTech Connect

    Hunter, C.

    2012-03-28

    Surface roughness values for the areas surrounding the H, D and N-Area meteorological towers were computed from archived 2010 meteorological data. These 15-minute-averaged data were measured with cup anemometers and bidirectional wind vanes (bivanes) 61 m above the surface. The results of the roughness calculation using the standard deviation of elevation angle {sigma}{sub E}, and applying the simple formula based on tree canopy height, gave consistent estimates for roughness around the H-Area tower in the range of 1.76 to 1.86 m (95% confidence interval) with a mean value of 1.81 m. Application of the {sigma}{sub E} method for the 61-m level at D and N-Areas gave mean values of 1.71 and 1.81 with confidence ranges of 1.62-1.81 and 1.73-1.88 meters, respectively. Roughness results are azimuth dependent, and thus are presented as averages over compass sectors spanning 22.5 degrees. Calculated values were compared to other methods of determining roughness, including the standard deviation of the azimuth direction, {sigma}{sub A}, and standard deviation of the wind speed, {sigma}{sub U}. Additional data was obtained from a sonic anemometer at 61-m on the H-Area tower during a period of a few weeks in 2010. Results from the sonic anemometer support our use of {sigma}{sub E} to calculate roughness. Based on the H-Area tower results, a surface roughness of 1.8 m using is recommended for use in dispersion modeling applications that consider the impacts of a contaminant release to individuals along the Site boundary. The canopy surrounding the H-Area tower is relatively uniform (i.e., little variance in roughness by upwind direction), and data supplied by the U.S. Forest Service at Savannah River show that the canopy height and composition surrounding the H-Area tower is reasonably representative of forested areas throughout the SRS reservation. For dispersion modeling analyses requiring assessments of a co-located worker within the respective operations area, recommended

  2. Laws of Flow in Rough Pipes

    NASA Technical Reports Server (NTRS)

    Nikuradse, J

    1950-01-01

    An experimental investigation is made of the turbulent flow of water in pipes with various degrees of relative roughness. The pipes range in size from 25 to 100 millimeters in diameter and from 1800 to 7050 millimeters in length. Flow velocities permitted Reynolds numbers from about 10 (sup. 4) to 10 (sup. 6). The laws of resistance and velocity distributions were obtained as a function of relative roughness and Reynolds number. Mixing length, as described by Prandtl's mixing-length formula, is discussed in relation to the experimental results.

  3. Rough and Steep Terrain Lunar Surface Mobility

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian

    2005-01-01

    In the summer of 2004, the NASA Exploration Systems Mission Directorate conducted an open call for projects relevant to human and robotic exploration of the Earth-Moon and Mars systems. A project entitled 'Rough and Steep Terrain Lunar Surface Mobility' was submitted by JPL and accepted by NASA. The principal investigator of this project describes the robotic vehicle being developed for this effort, which includes six 'wheels-on-legs' so that it can roll efficiently on relatively smooth terrain but walk (using locked wheels as footpads) when "the going gets rough".

  4. Roughness Perception of Haptically Displayed Fractal Surfaces

    NASA Technical Reports Server (NTRS)

    Costa, Michael A.; Cutkosky, Mark R.; Lau, Sonie (Technical Monitor)

    2000-01-01

    Surface profiles were generated by a fractal algorithm and haptically rendered on a force feedback joystick, Subjects were asked to use the joystick to explore pairs of surfaces and report to the experimenter which of the surfaces they felt was rougher. Surfaces were characterized by their root mean square (RMS) amplitude and their fractal dimension. The most important factor affecting the perceived roughness of the fractal surfaces was the RMS amplitude of the surface. When comparing surfaces of fractal dimension 1.2-1.35 it was found that the fractal dimension was negatively correlated with perceived roughness.

  5. Rough Fresnel zone plates over metallic surfaces.

    PubMed

    Salgado-Remacha, Francisco Javier; Sanchez-Brea, Luis Miguel; Alvarez-Rios, Francisco Javier; Bernabeu, Eusebio

    2010-04-01

    We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh-Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. PMID:20357856

  6. Evaluation of Dry, Rough Vacuum Pumps

    NASA Technical Reports Server (NTRS)

    Hunter, Brian

    2006-01-01

    This document provides information on the testing and evaluation of thirteen dry rough vacuum pumps of various designs and from various manufacturers. Several types of rough vacuum pumps were evaluated, including scroll, roots, and diaphragm pumps. Tests included long term testing, speed curve generation, voltage variance, vibrations emissions and susceptibility, electromagnetic interference emissions and susceptibility, static leak rate, exhaust restriction, response/recovery time tests, and a contamination analysis for scroll pumps. Parameters were found for operation with helium, which often is not provided from the manufacturer

  7. Surface roughness effects in elastohydrodynamic contacts

    NASA Technical Reports Server (NTRS)

    Tripp, J. H.; Hamrock, B. J.

    1985-01-01

    Surface roughness effects in full-film EHL contacts were studied. A flow factor modification to the Reynolds equation was applied to piezoviscous-elastic line contacts. Results for ensemble-averaged film shape, pressure distribution, and other mechanical quantities were obtained. Asperities elongated in the flow direction by a factor exceeding two decreased both film shape and pressure extrema at constant load; isotropic or transverse asperities increased these extrema. The largest effects are displayed by traction, which increased by over 5% for isotropic or transverse asperities and by slightly less for longitudinal roughness.

  8. Fused silica fine grinding with low roughness

    NASA Astrophysics Data System (ADS)

    Dai, Lei; Gu, Yongqiang; Wu, Di

    2014-08-01

    Lithography-optics is one of the most complex optical systems. The fine grinding process is the most important step before polishing. Roughness and sub-surface damage (SSD) are essential outputs of fine grinding. We demonstrate the method that use fix abrasive cup tool with CNC grinding machine to complete the fine grinding process, even instead of lapping process. And experiment sample roughness can reach 23.40nm rms and Ra 18.554nm. The SSD estimate is about 2 μm which is also smaller than commercial lapping process. The fine grinding output can satisfy the lithography optic fabrication demands and efficiently reduce the polishing time.

  9. Elastoplastic deformation of a roughness element

    NASA Astrophysics Data System (ADS)

    Murashov, M. V.; Kornev, Yu. V.

    2014-03-01

    The problem of using the mechanical properties determined in a macroexperiment in contact models for micron-sized roughness elements is considered. For a sample of commercial-purity AD1 aluminum, the penetration depths of an indenter into a rough surface element that are determined in a physical experiment and in a three-dimensional finite element simulation are compared. It is found that, with allowance for certain assumptions, the application of the properties determined in a macroexperiment requires their correction to take into account the cold work hardening of the surface layer in the sample material and the size effect.

  10. Surface roughness evolution of nanocomposite thin films

    SciTech Connect

    Turkin, A. A.; Pei, Y. T.; Shaha, K. P.; Chen, C. Q.; Vainshtein, D. I.; Hosson, J. Th. M. de

    2009-01-01

    An analysis of dynamic roughening and smoothening mechanisms of thin films grown with pulsed-dc magnetron sputtering is presented. The roughness evolution has been described by a linear stochastic equation, which contains the second- and fourth-order gradient terms. Dynamic smoothening of the growing interface is explained by ballistic effects resulting from impingements of ions to the growing thin film. These ballistic effects are sensitive to the flux and energy of impinging ions. The predictions of the model are compared with experimental data, and it is concluded that the thin film roughness can be further controlled by adjusting waveform, frequency, and width of dc pulses.

  11. Venus surface roughness and Magellan stereo data

    NASA Technical Reports Server (NTRS)

    Maurice, Kelly E.; Leberl, Franz W.; Norikane, L.; Hensley, Scott

    1994-01-01

    Presented are results of some studies to develop tools useful for the analysis of Venus surface shape and its roughness. Actual work was focused on Maxwell Montes. The analyses employ data acquired by means of NASA's Magellan satellite. The work is primarily concerned with deriving measurements of the Venusian surface using Magellan stereo SAR. Roughness was considered by means of a theoretical analyses based on digital elevation models (DEM's), on single Magellan radar images combined with radiometer data, and on the use of multiple overlapping Magellan radar images from cycles 1, 2, and 3, again combined with collateral radiometer data.

  12. Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles

    PubMed Central

    2016-01-01

    We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials. PMID:26821214

  13. β-Peptide bundles: Design. Build. Analyze. Biosynthesize.

    PubMed

    Wang, Pam S P; Schepartz, Alanna

    2016-06-14

    Peptides containing β-amino acids are unique non-natural polymers known to assemble into protein-like tertiary and quaternary structures. When composed solely of β-amino acids, the structures formed, defined assemblies of 14-helices called β-peptide bundles, fold cooperatively in water solvent into unique and discrete quaternary assemblies that are highly thermostable, bind complex substrates and metal ion cofactors, and, in certain cases, catalyze chemical reactions. In this Perspective, we recount the design and elaboration of β-peptide bundles and provide an outlook on recent, unexpected discoveries that could influence research on β-peptides and β-peptide bundles (and β-amino acid-containing proteins) for decades to come. PMID:27146019

  14. Stable parabolic Higgs bundles as asymptotically stable decorated swamps

    NASA Astrophysics Data System (ADS)

    Beck, Nikolai

    2016-06-01

    Parabolic Higgs bundles can be described in terms of decorated swamps, which we studied in a recent paper. This description induces a notion of stability of parabolic Higgs bundles depending on a parameter, and we construct their moduli space inside the moduli space of decorated swamps. We then introduce asymptotic stability of decorated swamps in order to study the behaviour of the stability condition as one parameter approaches infinity. The main result is the existence of a constant, such that stability with respect to parameters greater than this constant is equivalent to asymptotic stability. This implies boundedness of all decorated swamps which are semistable with respect to some parameter. Finally, we recover the usual stability condition of parabolic Higgs bundles as asymptotic stability.

  15. Infinite number of MSSMs from heterotic line bundles?

    NASA Astrophysics Data System (ADS)

    Groot Nibbelink, Stefan; Loukas, Orestis; Ruehle, Fabian; Vaudrevange, Patrick K. S.

    2015-08-01

    We consider heterotic E8×E8 supergravity compactified on smooth Calabi-Yau manifolds with line bundle gauge backgrounds. Infinite sets of models that satisfy the Bianchi identities and flux quantization conditions can be constructed by letting their background flux quanta grow without bound. Even though we do not have a general proof, we find that all examples are at the boundary of the theory's validity: the Donaldson-Uhlenbeck-Yau equations, which can be thought of as vanishing D-term conditions, cannot be satisfied inside the Kähler cone unless a growing number of scalar vacuum expectation values is switched on. As they are charged under various line bundles simultaneously, the gauge background gets deformed by these VEVs to a non-Abelian bundle. In general, our physical expectation is that such infinite sets of models should be impossible, since they never seem to occur in exact conformal field theory constructions.

  16. Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles.

    PubMed

    Maier, Alexander M; Weig, Cornelius; Oswald, Peter; Frey, Erwin; Fischer, Peer; Liedl, Tim

    2016-02-10

    We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials. PMID:26821214

  17. System for supporting bundled tube segments within a combustor

    DOEpatents

    Melton, Patrick Benedict

    2016-03-01

    A system for supporting bundled tube segments within a combustor includes an annular sleeve that extends circumferentially and axially within the combustor, a support lug that extends radially inward from the annular sleeve and an annular support frame that is disposed within the annular sleeve. The annular support frame includes an inner ring portion, an outer ring portion and a plurality of spokes that extend radially between the inner and outer ring portions. The inner ring portion, the outer ring portion and the plurality of spokes define an annular array of openings for receiving a respective bundled tube segment. The inner ring portion is connected to each bundled tube segment and the outer ring portion is coupled to the support lug.

  18. Betti numbers of graded modules and cohomology of vector bundles

    NASA Astrophysics Data System (ADS)

    Eisenbud, David; Schreyer, Frank-Olaf

    2009-07-01

    In the remarkable paper Graded Betti numbers of Cohen-Macaulay modules and the multiplicity conjecture, Mats Boij and Jonas Soederberg conjectured that the Betti table of a Cohen-Macaulay module over a polynomial ring is a positive linear combination of Betti tables of modules with pure resolutions. We prove a strengthened form of their conjectures. Applications include a proof of the Multiplicity Conjecture of Huneke and Srinivasan and a proof of the convexity of a fan naturally associated to the Young lattice. With the same tools we show that the cohomology table of any vector bundle on projective space is a positive rational linear combination of the cohomology tables of what we call supernatural vector bundles. Using this result we give new bounds on the slope of a vector bundle in terms of its cohomology.

  19. Fuel rod mechanical deformation during the PBF/LOFT lead rod loss-of-coolant experiments

    SciTech Connect

    Varacalle, Jr., D. J.; MacDonald, P. E.; Shiozawa, S.; Driskell, W. E.

    1980-01-01

    Results of four PBF/LOFT Lead Rod (LLR) sequential blowdown tests conducted in the Power Burst Facility (PBF) are presented. Each test employed four separately shrouded fuel rods. The primary objective of the test series was to evaluate the extent of mechanical deformation that would be expected to occur to low pressure (0.1 MPa), light water reactor design fuel rods when subjected to a series of double ended cold leg break loss-of-coolant accident (LOCA) tests, and to determine whether subjecting these deformed fuel rods to subsequent testing would result in rod failure. The extent of mechanical deformation (buckling, collapse, or waisting of the cladding) was evaluated by comparison of cladding temperature and system pressure measurements with out-of-pile experimental data, and by posttest visual examinations and cladding diametral measurements.

  20. On some transverse geometrical structures of lifted foliation to its conormal bundle.

    PubMed

    Ida, Cristian; Oană, Alexandru

    2015-01-01

    We consider the lift of a foliation to its conormal bundle and some transverse geometrical structures associated with this foliation are studied. We introduce a good vertical connection on the conormal bundle and, moreover, if the conormal bundle is endowed with a transversal Cartan metric, we obtain that the lifted foliation to its conormal bundle is a Riemannian one. Also, some transversally framed f(3, ε)-structures of corank 2 on the normal bundle of lifted foliation to its conormal bundle are introduced and an almost (para)contact structure on a transverse Liouville distribution is obtained. PMID:25834835

  1. Radiological characterization of spent control rod assemblies

    SciTech Connect

    Lepel, E.A.; Robertson, D.E.; Thomas, C.W.; Pratt, S.L.; Haggard, D.L.

    1995-10-01

    This document represents the final report of an ongoing study to provide radiological characterizations, classifications, and assessments in support of the decommissioning of nuclear power stations. This report describes the results of non-destructive and laboratory radionuclide measurements, as well as waste classification assessments, of BWR and PWR spent control rod assemblies. The radionuclide inventories of these spent control rods were determined by three separate methodologies, including (1) direct assay techniques, (2) calculational techniques, and (3) by sampling and laboratory radiochemical analyses. For the BWR control rod blade (CRB) and PWR burnable poison rod assembly (BPRA), {sup 60}Co and {sup 63}Ni, present in the stainless steel cladding, were the most abundant neutron activation products. The most abundant radionuclide in the PWR rod cluster control assembly (RCCA) was {sup 108m}Ag (130 yr halflife) produced in the Ag-In-Cd alloy used as the neutron poison. This radionuclide will be the dominant contributor to the gamma dose rate for many hundreds of years. The results of the direct assay methods agree very well ({+-}10%) with the sampling/radiochemical measurements. The results of the calculational methods agreed fairly well with the empirical measurements for the BPRA, but often varied by a factor of 5 to 10 for the CRB and the RCCA assemblies. If concentration averaging and encapsulation, as allowed by 10CFR61.55, is performed, then each of the entire control assemblies would be classified as Class C low-level radioactive waste.

  2. Passive electrical properties of rod outer segments

    PubMed Central

    Falk, Gertrude; Fatt, P.

    1968-01-01

    1. Measurements on a packed suspension of randomly oriented, dark-adapted frog rods at frequencies of 15 c/s-0·5 Mc/s indicate a behaviour similar to that of other biological materials. 2. Results are analysed on the assumption that the low-frequency limiting resistance is determined by current flowing in the suspending medium and that, of the rods, two thirds are oriented perpendicular to the applied field and one third parallel to it. Those parallel to the field are treated as non-conductors. 3. From the high-frequency limiting resistance the conductivity of the rod interior is calculated to vary linearly with the conductivity of the medium. The slope of the relation of internal to external conductivity is 0·50 with a limiting internal conductivity (at zero external) of 280 μmho/cm. 4. On the assumption that the suspension can be represented as a single-capacitance network, the characteristic frequency of impedance is used to calculate a capacitance for the rod surface of 1·54 μF/cm2. On the assumption of a distribution in properties of the suspension according to the theory of Bruggeman, the capacitance is calculated to have a value of about one half this. 5. At frequencies below 5 kc/s the impedance locus deviates from the curve describing the behaviour at higher frequencies. It is suggested that this may involve conduction in a thin layer extending along the surface of the rod. PMID:5685292

  3. Coiling of elastic rods on rigid substrates.

    PubMed

    Jawed, Mohammad K; Da, Fang; Joo, Jungseock; Grinspun, Eitan; Reis, Pedro M

    2014-10-14

    We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. PMID:25267649

  4. Dynamic behavior of rod photoreceptor disks.

    PubMed

    Chen, Chunhe; Jiang, Yunhai; Koutalos, Yiannis

    2002-09-01

    Eukaryotic cells use membrane organelles, like the endoplasmic reticulum or the Golgi, to carry out different functions. Vertebrate rod photoreceptors use hundreds of membrane sacs (the disks) for the detection of light. We have used fluorescent tracers and single cell imaging to study the properties of rod photoreceptor disks. Labeling of intact rod photoreceptors with membrane markers and polar tracers revealed communication between intradiskal and extracellular space. Internalized tracers moved along the length of the rod outer segment, indicating communication between the disks as well. This communication involved the exchange of both membrane and aqueous phase and had a time constant in the order of minutes. The communication pathway uses approximately 2% of the available membrane disk area and does not allow the passage of molecules larger than 10 kDa. It was possible to load the intradiskal space with fluorescent Ca(2+) and pH dyes, which reported an intradiskal Ca(2+) concentration in the order of 1 microM and an acidic pH 6.5, both of them significantly different than intracellular and extracellular Ca(2+) concentrations and pH. The results suggest that the rod photoreceptor disks are not discrete, passive sacs but rather comprise an active cellular organelle. The communication between disks may be important for membrane remodeling as well as for providing access to the intradiskal space of the whole outer segment. PMID:12202366

  5. Single Rod Vibration in Axial Flow

    NASA Astrophysics Data System (ADS)

    Weichselbaum, Noah; Wang, Shengfu; Bardet, Philippe

    2013-11-01

    Fluid structure interaction of a single rod in axial flow is a coupled dynamical system present in many application including nuclear reactors, steam generators, and towed antenna arrays. Fluid-structure response can be quantified thanks to detailed experimental data where both structure and fluid responses are recorded. Such datum deepen understanding of the physics inherent to the system and provide high-dimensionality quantitative measurements to validate coupled structural and CFD codes with various level of complexity. In this work, single rods fixed on both ends in a concentric pipe, are subjected to an axial flow with Reynolds number based on hydraulic diameter of Re =4000. Rods of varying material stiffness and diameter are utilized in the experiment resulting in a range of dimensionless U between 0.5 and 1, where U = (ρA/EI)1/2uL. Experimental measurements of the velocity field around the rod are taken with PIV from time-resolved Nd:YLF laser and a high speed CMOS camera. Three-dimensional and temporal vibration and deflection of the rod is recorded with shadowgraphy utilizing two sets of pulsed high power LED and dedicated CMOS camera. Through integration of these two diagnostics, it is possible to reconstruct the full FSI domain providing unique validation data.

  6. Coiling of elastic rods on rigid substrates

    PubMed Central

    Jawed, Mohammad K.; Da, Fang; Joo, Jungseock; Grinspun, Eitan; Reis, Pedro M.

    2014-01-01

    We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. PMID:25267649

  7. Medicare bundled payment: what is it worth to you?

    PubMed

    Harris, John; Elizondo, Idette; Isdaner, Andrew

    2014-01-01

    Hospital leaders who are contemplating participation in a bundled payment initiative should first assess current circumstances to determine the extent of the opportunity for their organizations. Those who have decided conditions are favorable for such an initiative should next perform a financial assessment that includes modeling direct contract results, assessing the financial impact of reduced utilization and of improved clinical care and operations, and evaluating the net financial impact. Hospital executives also should understand the competitive and strategic benefits that bundled payment offers. PMID:24511781

  8. Phase Transition to Bundles of Flexible Supramolecular Polymers

    NASA Astrophysics Data System (ADS)

    Huisman, B. A. H.; Bolhuis, P. G.; Fasolino, A.

    2008-05-01

    We report Monte Carlo simulations of the self-assembly of supramolecular polymers based on a model of patchy particles. We find a first-order phase transition, characterized by hysteresis and nucleation, toward a solid bundle of polymers, of length much greater than the average gas phase length. We argue that the bundling transition is the supramolecular equivalent of the sublimation transition, which results from a weak chain-chain interaction. We provide a qualitative equation of state that gives physical insight beyond the specific values of the parameters used in our simulations.

  9. One-sided ejaculation of echidna sperm bundles.

    PubMed

    Johnston, S D; Smith, B; Pyne, M; Stenzel, D; Holt, W V

    2007-12-01

    We report for the first time an unusual ejaculatory mechanism in the short-beaked echidna in which each side of the bilaterally symmetrical, rosettelike glans penis is used alternately, with the other being shut down. This is unparalleled in mammals but is reminiscent of the use of hemipenes in squamate reptiles, providing further reproductive evidence of a sauropsidian lineage in the Monotremata. Further, we describe the occurrence of motile sperm bundles in ejaculated echidna semen and provide scanning electron micrographs of their morphology. Sperm bundling appears to confer increased sperm motility, which may provide the potential for sperm competition between males. PMID:18171162

  10. Capture and manipulation of hybrid DNAs by carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Li, Zhenhai; Yang, Wei

    2010-05-01

    When approached from both sides, a piece of single-duplex-single DNA may be drawn into the inlets of two bundles of carbon nanotubes. This provides opportunities to manipulate the DNA by two bundles of nanotubes. The capture and manipulation processes envisaged above are simulated by molecular dynamics in this work. The radius of the carbon nanotube and the ambient temperature show the effects on the spontaneous insertion of DNA strands. This procedure, if successful, could be used for capturing expectant sdsDNAs, with subsequent manipulation to pull or to unzip the captured DNA.

  11. Artificial metalloenzymes derived from three-helix bundles

    PubMed Central

    Tebo, Alison G.; Pecoraro, Vincent L.

    2015-01-01

    Three-helix bundles and coiled-coil motifs are well-established de novo designed scaffolds that have been investigated for their metal-binding and catalytic properties. Satisfaction of the primary coordination sphere for a given metal is sufficient to introduce catalytic activity and a given structure may catalyze different reactions dependent on the identity of the incorporated metal. Here we describe recent contributions in the de novo design of metalloenzymes based on three-helix bundles and coiled-coil motifs, focusing on non-heme systems for hydrolytic and redox chemistry. PMID:25579452

  12. Surface roughness scattering in multisubband accumulation layers

    NASA Astrophysics Data System (ADS)

    Fu, Han; Reich, K. V.; Shklovskii, B. I.

    2016-06-01

    Accumulation layers with very large concentrations of electrons where many subbands are filled became recently available due to ionic liquid and other new methods of gating. The low-temperature mobility in such layers is limited by the surface roughness scattering. However, theories of roughness scattering so far dealt only with the small-density single subband two-dimensional electron gas (2DEG). Here we develop a theory of roughness-scattering limited mobility for the multisubband large concentration case. We show that with growing 2D electron concentration n the surface dimensionless conductivity σ /(2 e2/h ) first decreases as ∝n-6 /5 and then saturates as ˜(d aB/Δ2)≫1 , where d and Δ are the characteristic length and height of the surface roughness and aB is the effective Bohr radius. This means that in spite of the shrinkage of the 2DEG thickness and the related increase of the scattering rate the 2DEG remains a good metal.

  13. Surface roughness modulations by submesoscale currents

    NASA Astrophysics Data System (ADS)

    Rascle, Nicolas; Chapron, Bertrand; Nouguier, Frederic; Ponte, Aurelien; Mouche, Alexis; Molemaker, Jeroen

    2016-04-01

    At times, high resolution images of sea surface roughness can provide stunning details of submesoscale upper ocean dynamics. As interpreted, transformations of short scale wind waves by horizontal current gradients are responsible for those spectacular observations. Here we present two major advances towards the quantitative interpretation of those observations. First, we show that surface roughness variations mainly trace two particular characteristics of the current gradient tensor, the divergence and the strain in the wind direction. Local vorticity and shear in the wind direction should not affect short scale roughness distribution and would not be detectable. Second, we discuss the effect of the viewing direction using sets of quasi-simultaneous sun glitter images, taken from different satellites to provide different viewing configurations. We show that upwind and crosswind viewing observations can be markedly different. As further confirmed with idealized numerical simulations, this anisotropy well traces surface current strain area, while more isotropic contrasts likely trace areas dominated by surface divergence conditions. These findings suggest the potential to directly observe surface currents at submesoscale by using surface roughness observations at multiple azimuth viewing angles. They also pave the way towards a better understanding of the coupling between ocean, waves and atmosphere at high resolution.

  14. Thermal smoothing of rough surfaces in vacuo

    NASA Technical Reports Server (NTRS)

    Wahl, G.

    1986-01-01

    The derivation of equations governing the smoothing of rough surfaces, based on Mullins' (1957, 1960, and 1963) theories of thermal grooving and of capillarity-governed solid surface morphology is presented. As an example, the smoothing of a one-dimensional sine-shaped surface is discussed.

  15. Particle Sliding on a Rough Incline

    ERIC Educational Resources Information Center

    Zurcher, Ulrich

    2007-01-01

    We study a particle sliding on a rough inclined plane as an example of a mechanical problem with nonholonomic constraint. The particle is launched in an arbitrary direction so that its motion has both a horizontal and a "vertical" (i.e., up- and downhill) direction. The friction force acts along the instantaneous velocity, so that the horizontal…

  16. Three-tier rough superhydrophobic surfaces.

    PubMed

    Cao, Yuanzhi; Yuan, Longyan; Hu, Bin; Zhou, Jun

    2015-08-01

    A three-tier rough superhydrophobic surface was fabricated by growing hydrophobic modified (fluorinated silane) zinc oxide (ZnO)/copper oxide (CuO) hetero-hierarchical structures on silicon (Si) micro-pillar arrays. Compared with the other three control samples with a less rough tier, the three-tier surface exhibits the best water repellency with the largest contact angle 161° and the lowest sliding angle 0.5°. It also shows a robust Cassie state which enables the water to flow with a speed over 2 m s(-1). In addition, it could prevent itself from being wetted by the droplet with low surface tension (mixed water and ethanol 1:1 in volume) which reveals a flow speed of 0.6 m s(-1) (dropped from the height of 2 cm). All these features prove that adding another rough tier on a two-tier rough surface could futher improve its water-repellent properties. PMID:26184512

  17. Measurement and Correlation of Ice Accretion Roughness

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Hentschel, Daniel B.; Ruff, Gary A.

    2003-01-01

    Measurements were taken of the roughness characteristics of ice accreted on NACA 0012 airfoils in the NASA Glenn Icing Research Tunnel (IRT). Tests were conducted with size scaled, using models with chords of 26.7, 53.3, and 80.0 cm, and with liquid-water content scaled, both according to previously-tested scaling methods. The width of the smooth zone which forms on either side of the leading edge of the airfoil and the diameter of the roughness elements are presented in non-dimensional form as functions of the accumulation parameter. The smooth-zone width was found to decrease with increasing accumulation parameter. The roughness-element diameter increased with accumulation parameter until a plateau was reached. This maximum diameter was about 0.06 times twice the model leading-edge radius. Neither smooth-zone width nor element diameter were affected by a change in freezing fraction from 0.2 to 0.4. Both roughness characteristics appeared to scale with model size and with liquid-water content.

  18. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... rough air encounters will not cause the overspeed warning to operate too frequently. In the absence of...

  19. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... rough air encounters will not cause the overspeed warning to operate too frequently. In the absence of...

  20. 7 CFR 51.707 - Slightly rough texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Other Than Florida, California, and Arizona) Definitions § 51.707 Slightly rough texture. Slightly rough texture means that the skin is not smooth or fairly smooth but is not excessively rough or excessively... 7 Agriculture 2 2013-01-01 2013-01-01 false Slightly rough texture. 51.707 Section...